JP3233835B2 - Dry etching method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dry etching method using plasma.

[0002]

2. Description of the Related Art As a dry etching method, a sample stage, which is a cathode electrode, is set inside a chamber of a plasma generator, and a high-frequency power is applied to the sample stage to form a self-DC bias. 2. Description of the Related Art There is known a method in which a sample to be etched formed of a substrate, a film formed on a substrate, or the like is dry-etched by mainly or additionally using acceleration induction of ions toward a sample stage. As described above, the plasma using the high-frequency discharge is applied to dry etching of fine processing.

[0003] Advances in modern high-density semiconductor integrated circuits are bringing about changes that are comparable to the industrial revolution. Higher density has been realized by miniaturization of element dimensions, improvement of devices, enlargement of chip size, and the like. The miniaturization of device dimensions has been progressing to the order of the wavelength of light, and the use of excimer lasers and soft X-rays for lithography is being studied.
In order to realize a fine pattern, dry etching and thin film formation play an important role together with lithography.

[0004] Dry etching applied to fine processing will be described below. Dry etching is a technique for removing unnecessary portions of a sample to be etched by utilizing a chemical or physical reaction between radicals, ions, or the like generated by plasma and the solid surface of the sample to be etched. Reactive ion etching (RIE), which is most widely used as a dry etching technique, is such that when a sample to be etched is exposed to a high-frequency discharge plasma of an appropriate gas, an unnecessary portion of the sample to be etched is removed by an etching reaction. It is. The necessary parts are usually protected by the photoresist pattern used as a mask.

In the following description, a pattern formed on a sample to be etched when dry etching is performed on the sample to be etched using a resist pattern as a mask is particularly called a line pattern.

[0006] In the dry etching technique, the formation of a substantially vertical etching shape in accordance with a mask pattern of a fine dimension is performed by using a line pattern (a plurality of line patterns formed close to each other) located inside a line pattern group. This will be hereinafter also referred to as an internal line pattern), an outermost line pattern in a line pattern group (hereinafter referred to as an external line pattern), and an isolated line pattern formed independently of the line pattern group. In addition, it is required to reduce the dimensional difference between the isolated line pattern (or the external line pattern) and the internal line pattern as much as possible.

As a countermeasure against these requirements, conventionally, the gas pressure in the chamber is lowered to increase the degree of vacuum, so that ions are transported to the sample stage while being accelerated in a sheath region formed near the sample. In order to minimize the scattering due to collisions between ions and neutral particles as much as possible, in order to prevent etching on the line pattern side wall due to obliquely incident ions always present at a certain ratio,
A method of adding a gas for protecting the side wall which generates a radical for protecting the side wall has been adopted.

[0008]

As described above, the etching method employing low vacuum and addition of a gas for protecting the side walls has the following problems. (1) The ion incident angle distribution has higher perpendicularity to the sample surface. (2) The etching protection of the side wall of the line pattern by obliquely incident ions can be controlled to some extent, and the formation of a substantially vertical etching shape according to the mask pattern dimension can be changed to an isolated line pattern (or an external line pattern) or an internal line pattern. On the other hand, it is difficult to realize them simultaneously (although they can be realized individually) and (3) to make the dimensional difference between an isolated line pattern (or an external line pattern) and an internal line pattern sufficiently small. there were.

In view of the above, according to the present invention, in a dry etching process using plasma, gas pressure, gas ratio, gas exhaust amount, temperature of a sample stage, bias and
By optimizing the power combination, the energy and angular distribution of ions near the surface of the sample stage and the ratio of radicals responsible for side wall protection are controlled, and as a result, any of isolated line patterns, external line patterns, and internal line patterns can be controlled. An object of the present invention is to realize formation of an etched shape that is perpendicular to the other, and sufficiently reduce a dimensional difference between an isolated line pattern (or an external line pattern) and an internal line pattern.

[0010]

SUMMARY OF THE INVENTION The present invention relates to a gas pressure of a raw material gas introduced into a vacuum chamber, a discharge amount of a gas discharged from the vacuum chamber, and a high-frequency power applied for forming a self-bias in the vacuum chamber. When at least one parameter of a parameter group consisting of a frequency, a power of the high frequency power, a ratio of the side wall protecting gas in the source gas, and a temperature of the sample stage is changed, the deposition of the side wall protecting radical on the side wall of the line pattern is performed. The amount and the amount of etching of the deposited sidewall protective film by ions are
The inventors have found that the isolated line pattern, the outer line pattern, and the inner line pattern change independently, and have made this finding.

Hereinafter, in the dry etching method,
(1) Values of external operation parameters such as gas pressure, gas ratio, gas displacement, bias power, frequency of high frequency power, and sample stage temperature, isolated line pattern of sample to be etched on sample stage, and internal line pattern sidewall And the relationship with the values of the plasma internal parameters such as the ratio of the side wall protecting radicals flying on each side wall of the outer line pattern, the side wall protecting radical adsorption rate, ion flux, ion angle distribution, ion energy distribution, and (2) isolated line The relationship between the deposition amount and the etching amount of the side wall protective film deposited on each side wall of the pattern (or the outer line pattern) and the inner line pattern will be described.

In the following description, the content of comparing the isolated line pattern with the internal line pattern also applies to the comparison between the external surface of the external line pattern and the internal line pattern. (A) First, the above-described relationship centered on the value of the external operation parameter called gas pressure will be described. (a) The amount of the sidewall protection film deposited on the sidewall of the line pattern by the sidewall protection radical which plays a role of the sidewall protection such as a reaction product radical existing in the chamber or a radical generated from the sidewall protection additive gas. , The isolated line pattern is greater than the internal line pattern, regardless of the gas pressure in the chamber. The reason for this is that the expected solid angle of the side wall protecting radical flux that is incident almost isotropically from above the sample to be etched is almost π / 2 in the case of the isolated line pattern side wall, while the internal line angle is about π / 2. It is smaller than π / 2 in the case of the pattern side wall, and is considerably smaller than π / 2 particularly when the pattern aspect ratio (the value obtained by dividing the line height of the line and space pattern by the space width) is large. Because it becomes.

As the ratio of the side wall protective radical is reduced, the amount of the side wall protective film deposited on the side wall of the isolated line pattern and the amount of the side wall protective film deposited on the side wall of the internal line pattern decrease while maintaining a constant ratio. . However, the reduction amount of the sidewall protection film with respect to the reduction amount of the ratio of the sidewall protection radical is larger in the isolated line pattern sidewall than in the internal line pattern sidewall. That is, the amount of change in the thickness of the sidewall protective film on the side wall of the isolated line pattern is larger than the amount of change in the thickness of the sidewall protective film on the side wall of the internal line pattern. (b) Next, the behavior of the incident ions will be described.

The incident ions are incident on the surface of the sample while being accelerated in a direction substantially perpendicular to the surface of the sample table by an electric field in a direction perpendicular to the surface of the sample table provided in the sheath region. However, due to collision with the neutral particles in the sheath region, the light enters the sample surface with an angle component scattered to some extent.

The ions obliquely incident on the surface of the sample scrape off the side wall protective film on the side wall of the line pattern on the side wall of the line pattern standing perpendicular to the surface of the sample, and after etching. This has the effect of changing the pattern profile from a forward taper to a vertical one or from a vertical one to a reverse taper. The more the incident angle of the ions becomes perpendicular to the side wall of the line pattern, that is, the larger the scattering angle of the ions, the larger the etching ability with respect to the side wall protective film. Conversely, ions incident perpendicularly to the sample surface have an incident angle substantially parallel to the side wall of the line pattern, and therefore have a small etching ability with respect to the side wall protective film.

The above phenomenon is particularly remarkable on the side wall of the isolated line pattern because the expected solid angle of obliquely incident ions is large, and the incident ions directly collide with the side wall. On the other hand, on the side wall of the internal line pattern, the expected solid angle of the obliquely incident ions is small, particularly when the aspect ratio of the line pattern is large.
Therefore, incident ions having a scattering angle of a certain size or more are reflected without entering the space portion of the line-and-space pattern. In other words, the ion angle distribution component of the incident ion having a large scattering angle cannot fly directly to the lower part of the side wall of the internal line pattern, but is more perpendicular to the sample surface and has a relatively small scattering angle. Only the ion angle distribution component can fly selectively. That is, of the ion flux having a wide ion angle distribution component, only a component having a certain scattering angle or less is collimated, and there is an effect of allowing the ion beam to fly below the side wall of the internal line pattern. Hereinafter, this effect will be referred to as an “ion collimation effect”.

In the vicinity of the upper part of the side wall of the internal line pattern, incident ions having a large scattering angle which are incident on the internal line pattern are not reflected several times between the internal line pattern side wall of the line pattern group and the opposing line pattern side wall. It cannot penetrate into the lower part of the pattern side wall. During this time, the energy of the incident ions decreases and the ability to etch the deposited protective film decreases. Also, the incident ion flux is reduced as compared with the isolated line pattern. (c) The above phenomena can be summarized as follows.
That is, (1) the side wall of the isolated line pattern has a larger change in the deposition amount of the side wall protective film with respect to the change of the ratio of the side wall protecting radical in the chamber than the inner line pattern side wall. (2) Due to the ion collimation effect, the effect of shaving the side wall protective film by obliquely incident ions is greater in the isolated line pattern than in the inner line pattern. (3) The change in the ion incident angle appears as a large change in the etching amount of the side wall protective film on the side wall of the isolated line pattern.

As described above, the isolated line pattern is relatively sensitive to the change in the ratio of the sidewall protecting radical and the ion incident angle, and the internal line pattern is relatively insensitive. (d) As described above, ions enter the sample surface with an angle component scattered to some extent due to collision with neutral particles in the sheath region, but in a high vacuum region where the gas pressure is sufficiently low. The incident ions are incident on the sample surface with little collision with neutral particles in the sheath region, many components that are incident relatively vertically, and a relatively small scattering angle as a whole. That is, in the case of a high vacuum region, many incident ions are incident in a substantially uniform shape along the side wall of the line pattern. This effect will be referred to as a “pseudo-parallel beam effect”.

In the case of such an incident ion angle distribution, the ion flux incident on the side wall of the isolated line pattern is larger than the ion flux incident on the side wall of the internal line pattern, but the difference is larger as in the case of the medium vacuum region. There is no. That is, the difference in the etching ability of the deposited protective film with respect to the isolated line pattern and the internal line pattern is not so different as in the case of the medium vacuum region. Further, the angle of the incident ions with respect to the side wall is relatively small, and the ratio of ions incident at a large angle on the line pattern side wall is small.
For this reason, the ability to etch the deposited protective film is smaller than that in the case of the medium vacuum region, and is particularly small on the side wall of the isolated line pattern. (e) In the above description, the relationship between the deposition amount of the sidewall protective film and the etching amount of the deposited protective film by obliquely incident ions has been described, but the amount of the deposited protective film is small,
When the amount of etching of the protective film due to obliquely incident ions is larger than the amount of deposition of the protective film, the profile of the line pattern of the sample to be etched has an inverse taper, and the size of the line pattern is smaller than the size of the resist mask.
In this case, when the gas pressure is reduced to reduce the ratio of obliquely incident ions, the angle becomes perpendicular from the reverse taper, and
The decrease in the line pattern dimension of the sample to be etched is also reduced. (B) Next, the above relationship centering on the combination of the two external operating parameters of the gas pressure P and the displacement Q will be described.

When the gas pressure P is increased, the following changes occur in the plasma internal parameters. The standard deviation of ion scattering angle representing the spread of the incident ion angular distribution σ increases as mentioned above, also the ion energy E _i of the ions incident on the sample surface is reduced. Since an increase in the gas pressure P means an increase in the source gas, the reactive radical flux F _R and the ion flux _Fi are increased as long as the input power is capable of sufficiently ionizing and exciting the source gas. As a result, the ratio of sidewall protection radicals such as reaction products and sputtered resist in the chamber increases, resulting in an increase in the sidewall protection radical bundle F _RP .

[0021] The standard deviation σ of ion scattering angles assuming a ion energy E _i and normal distribution, an internal parameter related to the etching ability of the side wall protective film deposited amount, a decrease in ion energy E _i is the etching ability Since the decrease causes the increase in the standard deviation σ of the ion scattering angle, the etching capability is improved. Therefore, it cannot be simply determined whether the increase in the gas pressure P results in the improvement or the reduction in the etching capability. On the other hand, an increase in the side wall protecting radical bundle F _RP clearly leads to an increase in the amount of side wall protecting film deposition. Therefore, it cannot be simply determined whether an increase in the gas pressure P causes an increase or a decrease in the deposition amount of the sidewall protective film.

However, if the gas exhaust amount is increased while the gas pressure P is kept constant to reduce the ratio of the sidewall protecting radicals in the chamber, the etching of the sidewall protecting film increases the film deposition amount. Become better. That is,
By controlling the displacement, the thickness of the sidewall protective film can be controlled. (C) will be described the relationship around the combination of the two external operating parameters of the bias power W _B and the exhaust amount Q.

[0023] Increasing the bias power W _B, can be considered a change in internal plasma parameters such as:.
First, the energy E _i of the ions incident on the sample surface is increased. The ion scattering angle standard deviation σ decreases. Also, an increase in the bias power W _B, since means an increase of the ionization excitation of the raw material gas in the vicinity of the sample surface, resulting in increased ion flux F _i and the reactive radical flux F _R. As a result,
The ratio of side wall protecting radicals such as reaction products and sputtered resist in the chamber increases, resulting in an increase in the side wall protecting radical bundle F _RP .

The ion energy E _i , the ion flux F _i and the ion scattering angle standard deviation σ are internal parameters related to the etching ability of the sidewall protective deposition film. An increase in the ion energy E _i and the ion flux F _i leads to an improvement in the etching ability. On the other hand, a decrease in the ion scattering angle standard deviation σ and an increase in the sidewall protection radical flux F _{RP result in} an increase in the sidewall protection film deposition amount. Therefore, increase in the bias power W _B can not be determined in simple what results in a decrease or bring an increase in the side wall protective film deposited amount.

[0025] However, while maintaining a bias power W _B constant, if tried to decrease the percentage of the allowed and sidewall protection radical increase emissions, increased etching of the sidewall protection film is deposited amount of the side wall protective film Will be better than That is, the thickness of the sidewall protection film can be controlled by controlling the exhaust amount. (D) Next, the above-described relationship centering on a combination of two external operating parameters, ie, the frequency f of the high frequency power and the gas pressure P will be described.

That is, the cathode-side sheath width d formed near the sample stage is as follows.

D = K ₁ / (P ^m · f ⁿ ) (1) where P is a gas pressure, f is a frequency, and m is a positive real number, which is larger than approximately 1/3 and approximately 1/2. Less than. n is a positive real number that is greater than approximately ２ and less than approximately 1. This is because K. Harafuji, A. Yama
no and M. Kubota: Jpn. J. Appl. Phys. vol.33 (1994)
p2212, and N.Mutsukura, K.Kobayashi and Y.Machi:
This is already described in J. Appl. Phys. Vol. 68 (1990) p.2657.

The mean free path λ of ions mainly derived from elastic collision scattering and charge exchange scattering between ions and neutral particles is inversely proportional to the gas pressure P and can be expressed as follows. .

Λ = K ₂ / P (2) While ions starting from the boundary between the bulk plasma region and the sheath region are transported onto the cathode having the sample stage, they are scattered by collision with neutral particles in the sheath region. The quantity η, which is proportional to the probability, is

Η = d / λ (3) By substituting equations (1) and (2) into equation (3), η = d / λ = (K ₁ / (P ^m · f ⁿ )) × (P / K ₂ ) = (K ₁ / K ₂ ) × (P ^{1 -m} / f ⁿ ) to (K ₁ / K ₂ ) × (P / f) ^1/2 Here, K ₁ and K ₂ are constants, respectively, and means that they are almost equal. The following conclusions are obtained from the above equations.

When the gas pressure P and the frequency f are increased,
From equation (1), the sheath width d, which is the distance traveled while the ions starting from the boundary between the bulk plasma region and the sheath region travel while being transported onto the sample stage, becomes shorter. The probability of scattering due to collision with the conductive particles is reduced.

When the gas pressure P is increased, the mean free path λ of the ions is shortened according to the equation (2), and from this viewpoint, the scattering probability due to the collision of the ions with the neutral particles is increased.

When the gas pressure P is reduced and the frequency f is increased to reduce P / f, the probability of scattering of ions due to collision with neutral particles in the sheath region can be reduced according to the equation (3). For this reason, when the gas pressure P is low and the frequency f is high, the energy attenuation of the ions is suppressed, and the direction of the ions is made uniform so that the ions enter the sample almost perpendicularly.
Further, it is possible to suppress the attenuation of the ion flux density reaching the sample, thereby improving the etching throughput and achieving sufficient etching anisotropy.

When the gas pressure P and the frequency f are reduced,
From equation (1), the sheath width d is longer, and from this viewpoint, the probability of scattering of ions due to collision with neutral particles increases.

When the gas pressure P is reduced, the mean free path λ of the ion is increased from the equation (2), and from this viewpoint, the scattering probability due to the collision of the ion with the neutral particles is reduced.

When the gas pressure P is increased and the frequency f is decreased to increase P / f, the probability of scattering of ions due to collision with neutral particles in the sheath region can be increased from the equation (3). Therefore, when the gas pressure P is increased and the frequency f is decreased, the energy of the ions is attenuated, and the directionality of the ions is slightly disordered so that the ions are incident on the sample.
Further, the ion flux density reaching the sample can be attenuated, thereby reducing the etching ability. (E) Next, the above-mentioned relationship centered on the external operation parameter of the sample stage temperature will be described.

The adsorption rate of the reaction product radicals present in the chamber and the side wall protecting radicals generated from the side wall protecting additive gas on the side wall of the line pattern generally increases as the temperature of the side wall of the line pattern (ie, the sample temperature) increases. Become smaller.

On the side wall of the isolated line pattern, the expected solid angle with respect to the side wall protecting radical bundle incident almost isotropically from above the sample is approximately π / 2, which is sufficiently large. Fully reaches the lower sidewall.

However, on the side wall of the internal line pattern, the expected solid angle is small, and especially when the pattern aspect ratio is large, the expected solid angle is considerably small. Must repeat the adsorption and re-emission on the side wall of the internal line pattern several times.

In this case, when the temperature of the side wall of the line pattern (that is, the sample temperature) is low, the adsorption rate increases, and most of the side wall protecting radicals adhere to the resist mask side wall above the internal line pattern, and the inner side. The sidewall protecting radical does not sufficiently reach the sidewall below the line pattern. On the other hand, if the temperature of the side wall of the line pattern is high, the adsorption rate becomes small, and the side wall protecting radical sufficiently reaches the side wall below the internal line pattern.

A detector for evaluating the ratio of a sidewall protecting radical which plays a role of protecting the sidewall in the plasma, a detector for evaluating an ion flux and energy distribution of an ion which plays a role of etching the deposited sidewall protecting film, and The above-mentioned plurality of external control parameters can be optimized by using a signal output from a sheath width detector or the like for evaluating the angular distribution.

Further, the completion of the main etching is determined using the signal of the etching end point detector installed in the plasma generation chamber, the etching is performed under the main etching condition until the main etching is completed, and thereafter, the over etching condition is performed. Is programmed so that an automatic two-stage etching can be performed.

Hereinafter, the solution means specifically taken by the present invention will be described.

In a first dry etching method according to the present invention, a sample to be etched placed on the sample stage and having a resist pattern formed on the surface is etched in a vacuum chamber having a sample stage below. And a source gas composed of an etching gas to be etched and a sidewall protecting gas for generating sidewall protecting radicals for protecting sidewalls of a line pattern formed by etching the sample to be etched. Generate ions and apply high-frequency power to the sample stage to
A dry etching method for guiding the ions to the sample stage by forming a C bias and thereby performing etching on the sample to be etched is intended for a plurality of the line patterns formed close to each other. The line width of the first line pattern composed of the line patterns located inside in the line pattern group is formed in isolation from the line pattern located outmost in the line pattern group or the line pattern group. When the line width of the second line pattern made of a line pattern is smaller than the line width of the second line pattern, and the line width of the first and second line patterns is larger than the line width of the resist pattern, the first and second lines are formed. The etching amount with respect to the side wall of the line pattern increases and The gas pressure of the source gas introduced into the vacuum chamber and the exhaustion from the vacuum chamber are performed so that the etching amount on the side wall of the first line pattern is relatively smaller than the etching amount on the side wall of the second line pattern. A parameter for changing at least one parameter of a parameter group consisting of a gas discharge amount, a frequency of the high-frequency power, a power of the high-frequency power, a ratio of the side wall protecting gas to the source gas, and a temperature of the sample stage. It has a control step.

According to the first dry etching method, in the parameter control step, the etching amount for the first and second line patterns increases, and the etching amount for the first line pattern is smaller than the etching amount for the second line pattern. The line width of the first line pattern is set to the second
And the line widths of the first and second line patterns approach the line width of the resist pattern, so that the line widths of the first and second line patterns are optimized.

In the first dry etching method, it is preferable that the parameter control step includes a step of increasing a discharge amount of gas discharged from the vacuum chamber.

By doing so, the side wall protection radical in the vacuum chamber is reduced, and in particular, the amount of the side wall protection film deposited on the side wall of the second line pattern is reduced. The etching effect is relatively increased. Therefore, the dimension reduction amount of the second line pattern is larger than the dimension reduction amount of the first line pattern.

In the first dry etching method, it is preferable that the parameter control step includes a step of reducing a ratio of the side wall protecting gas to the source gas.

By doing so, the side wall protection radical in the vacuum chamber is reduced, and in particular, the amount of the side wall protection film deposited on the side wall of the second line pattern is reduced. The etching effect is relatively increased. Therefore, the dimension reduction amount of the second line pattern is larger than the dimension reduction amount of the first line pattern.

In the first dry etching method, the parameter control step includes a step of increasing a gas pressure of a source gas introduced into the vacuum chamber, and a step of increasing power of the high frequency power. Is preferred.

In this manner, the decrease in ion energy due to the increase in gas pressure is compensated for by the increase in high-frequency power, the effect of obliquely incident ions on the sidewall protective film is increased, and the angular distribution of incident ions is expanded. And the etching effect of the first line pattern on the sidewall protection film is relatively reduced. Therefore, the dimension reduction amount in the first and second line patterns increases, and the spread of the angle distribution of the incident ions increases, so that the etching effect of the first line pattern on the sidewall protection film is larger than that of the second line pattern. Are relatively reduced, the dimension reduction amount of the first line pattern is smaller than the dimension reduction amount of the second line pattern.

In the first dry etching method, the parameter control step includes a step of increasing a gas pressure of a source gas introduced into the vacuum chamber, and a step of increasing a discharge amount of a gas discharged from the vacuum chamber. It is preferable to have

By doing so, the amount of the side wall protective film deposited on the side wall of the line pattern is reduced by reducing the side wall protective radical in the vacuum chamber, so that the dimension reduction amount in the first and second line patterns is increased. At the same time, the spread of the angle distribution of the incident ions becomes large and the etching effect of the first line pattern on the side wall protective film is relatively reduced. Therefore, the dimension reduction amount of the first line pattern is reduced by the dimension of the second line pattern. It is smaller than the reduction amount.

[0054] In the first dry etching method, it is preferable that the parameter control step includes a step of increasing the temperature of the sample stage.

By doing so, especially the side wall protection radicals deposited on the side walls of the second line pattern are reduced, the size reduction in the first and second line patterns is increased, and the side wall protection by obliquely incident ions is performed. Since the etching effect on the film is increased, the dimension reduction amount of the second line pattern is larger than the dimension reduction amount of the first line pattern.

The second dry etching method according to the present invention is directed to the same dry etching method as the first dry etching method, and is directed to the inside of a line pattern group consisting of a plurality of line patterns formed close to each other. The line width of the first line pattern composed of the line patterns located in the line pattern group is the outermost one of the line patterns in the line pattern group or the second line pattern composed of the line patterns formed separately from the line pattern group. When the line width of the first and second line patterns is smaller than the line width of the first and second line patterns, and the line width of the first and second line patterns is smaller than the line width of the resist pattern, The etching amount is reduced and the side wall of the first line pattern is The gas pressure of the source gas introduced into the vacuum chamber, the discharge amount of the gas discharged from the vacuum chamber, the high-frequency wave, so that the etching amount is relatively smaller than the etching amount on the side wall of the second line pattern. A parameter control step of changing at least one parameter of a parameter group consisting of a power frequency, a power of the high-frequency power, a ratio of the sidewall protecting gas to the source gas, and a temperature of the sample stage.

According to the second dry etching method, in the parameter control step, the amount of etching for the first and second line patterns is reduced, and the amount of etching for the first line pattern is smaller than the amount of etching for the second line pattern. Is controlled so as to relatively decrease, the line width of the first line pattern approaches the line width of the second line pattern, and the line width of the first and second line patterns is changed to the line width of the resist pattern. , The line widths of the first and second line patterns are optimized.

In the second dry etching method, it is preferable that the parameter control step includes a step of reducing a gas pressure of a source gas introduced into the vacuum chamber.

By doing so, the obliquely incident ions are reduced, and the etching effect of the obliquely incident ions on the side wall protective film is reduced, so that the amount of dimensional reduction in the first and second line patterns is reduced.

[0060] In the second dry etching method, it is preferable that the parameter control step includes a step of reducing a discharge amount of gas discharged from the vacuum chamber.

In this way, the amount of the side wall protective film deposited on the side wall of the line pattern increases due to an increase in the side wall protective radical in the vacuum chamber, and the amount of the side wall protective film deposited on the side wall of the line pattern increases. So the first and second
Since the reduction in the dimension of the second line pattern is significantly reduced in the second line pattern as well as the reduction in the etching effect on the sidewall protective film due to the obliquely incident ions, the reduction in the dimension of the second line pattern is reduced. It is smaller than the dimension reduction amount of the pattern.

[0062] In the second dry etching method, it is preferable that the parameter control step includes a step of increasing the temperature of the sample stage.

In this manner, the side wall protection radicals deposited on the side walls of the line pattern are reduced, the size reduction amount in the first and second line patterns is increased, and the etching effect on the side wall protection film by obliquely incident ions is increased. Therefore, the dimension reduction amount of the second line pattern is equal to the first line pattern.
Is larger than the dimension reduction amount of the line pattern.

The third dry etching method according to the present invention is directed to the same dry etching method as the first dry etching method, and is directed to the inside of a line pattern group consisting of a plurality of line patterns formed close to each other. The line width of the first line pattern composed of the line patterns located in the line pattern group is the outermost one of the line patterns in the line pattern group or the second line pattern composed of the line patterns formed separately from the line pattern group. When the line width of the first and second line patterns is larger than the line width of the first and second line patterns, and the line width of the first and second line patterns is larger than the line width of the resist pattern, As the etching amount increases, the side wall of the first line pattern The gas pressure of the raw material gas introduced into the vacuum chamber, the discharge amount of the gas discharged from the vacuum chamber, and the high-frequency wave so that the etching amount is relatively larger than the etching amount on the side wall of the second line pattern. A parameter control step of changing at least one parameter of a parameter group consisting of a power frequency, a power of the high-frequency power, a ratio of the sidewall protecting gas to the source gas, and a temperature of the sample stage.

According to the third dry etching method, in the parameter control step, the amount of etching for the first and second line patterns increases and the amount of etching for the first line pattern is smaller than the amount of etching for the second line pattern. Is controlled so as to relatively increase, the line width of the first line pattern approaches the line width of the second line pattern, and the line widths of the first and second line patterns are changed to the line width of the resist pattern. , The line widths of the first and second line patterns are optimized.

[0066] In the third dry etching method, the parameter control step may include a step of increasing the power of the high-frequency power and a step of increasing a discharge amount of gas discharged from the vacuum chamber. preferable.

In this way, the amount of the side wall protection film deposited on the side wall of the line pattern is reduced by reducing the side wall protection radical in the vacuum chamber, so that the dimension reduction amount in the first and second line patterns is increased. At the same time, the spread of the angle distribution of the incident ions becomes smaller, and the etching effect of the first line pattern on the side wall protective film is relatively increased. Therefore, the dimensional reduction amount of the first line pattern becomes smaller than that of the second line pattern. It increases more than the dimension reduction.

In the third dry etching method, it is preferable that the parameter control step includes a step of reducing a gas pressure of a source gas introduced into the vacuum chamber.

By doing so, the obliquely incident ions are reduced, and the reduction of the etching effect on the side wall protective film due to the obliquely incident ions appears remarkably in the second line pattern. To be reduced.

In this case, the parameter control step includes:
It is preferable that the method further includes a step of increasing a discharge amount of the gas discharged from the vacuum chamber.

By doing so, the amount of the side wall protection film deposited on the side wall of the line pattern decreases due to the reduction of the side wall protection radical in the vacuum chamber, and the dimension reduction amount in the first and second line patterns increases. At the same time, the spread of the angle distribution of the incident ions becomes smaller, and the etching effect of the first line pattern on the side wall protective film is relatively increased. Therefore, the dimensional reduction amount of the first line pattern becomes smaller than that of the second line pattern. It increases more than the dimension reduction.

In the third dry etching method, it is preferable that the parameter control step includes a step of increasing a frequency of the high frequency power.

In this manner, the sheath width is reduced, the ratio of obliquely incident ions is reduced, and the reduction of the etching effect on the side wall protective film due to the obliquely incident ions is noticeable in the second line pattern. The dimension reduction amount of the line pattern is relatively reduced.

In the third dry etching method, it is preferable that the parameter control step includes a step of increasing the temperature of the sample stage.

By doing so, the sidewall protecting radicals deposited on the sidewalls of the line pattern are reduced, and the amount of dimensional reduction in the first and second line patterns is increased.
Since the etching effect on the sidewall protective film by the obliquely incident ions is increased, the dimension reduction amount of the second line pattern is larger than the dimension reduction amount of the first line pattern.

The fourth dry etching method according to the present invention is directed to the same dry etching method as the first dry etching method, and is directed to the inside of a line pattern group consisting of a plurality of line patterns formed close to each other. The line width of the first line pattern composed of the line patterns located in the line pattern group is the outermost one of the line patterns in the line pattern group or the second line pattern composed of the line patterns formed separately from the line pattern group. When the line width of the first and second line patterns is larger than the line width of the first and second line patterns, and the line width of the first and second line patterns is smaller than the line width of the resist pattern, The etching amount is reduced and the side wall of the first line pattern is The gas pressure of the raw material gas introduced into the vacuum chamber, the discharge amount of the gas discharged from the vacuum chamber, and the high-frequency wave so that the etching amount is relatively larger than the etching amount on the side wall of the second line pattern. A parameter control step of changing at least one parameter of a parameter group consisting of a power frequency, a power of the high-frequency power, a ratio of the sidewall protecting gas to the source gas, and a temperature of the sample stage.

According to the fourth dry etching method, in the parameter control step, the amount of etching for the first and second line patterns is reduced, and the amount of etching for the first line pattern is smaller than the amount of etching for the second line pattern. Is controlled so as to relatively increase, the line width of the first line pattern approaches the line width of the second line pattern, and the line widths of the first and second line patterns are changed to the line width of the resist pattern. , The line widths of the first and second line patterns are optimized.

[0078] In the fourth dry etching method, it is preferable that the parameter control step includes a step of reducing a discharge amount of gas discharged from the vacuum chamber.

In this case, the amount of the side wall protection radical in the vacuum chamber increases and the amount of the side wall protection film deposited on the side wall of the line pattern relatively increases particularly in the second line pattern. In addition to the reduction in the dimension of the second line pattern, the reduction in the etching effect on the side wall protective film due to the obliquely incident ions significantly appears in the second line pattern. It is smaller than the dimension reduction amount of the line pattern.

In the fourth dry etching method, it is preferable that the parameter control step includes a step of increasing a ratio of the side wall protecting gas to the source gas.

In this way, the amount of the side wall protection film deposited on the side wall of the line pattern increases due to an increase in the side wall protection radicals in the vacuum chamber, so that the dimension reduction amount in the first and second line patterns is reduced. At the same time, the reduction of the etching effect on the side wall protective film due to the obliquely incident ions appears remarkably in the second line pattern. Therefore, the dimension reduction of the second line pattern is smaller than the dimension reduction of the first line pattern. .

[0082] In the fourth dry etching method, it is preferable that the parameter control step includes a step of increasing a frequency of the high frequency power.

In this manner, the sheath width is reduced, the ratio of obliquely incident ions is reduced, and the reduction of the etching effect on the side wall protective film due to the obliquely incident ions is noticeable in the second line pattern. The dimension reduction amount of the line pattern is relatively reduced.

In this case, the parameter control step includes:
It is preferable that the method further includes a step of reducing the gas pressure of the source gas introduced into the vacuum chamber.

In this manner, obliquely incident ions are greatly reduced, and the etching effect of the obliquely incident ions on the side wall protective film is reduced, and the reduction of the obliquely incident ions on the side wall protective film is reduced in the second line pattern. Since it appears remarkably, the dimension reduction amount of the second line pattern is smaller than the dimension reduction amount of the first line pattern.

[0086] In the fourth dry etching method, it is preferable that the parameter control step includes a step of lowering the temperature of the sample stage.

In this way, the amount of the side wall protective film deposited on the side wall of the line pattern is increased, so that the dimensional reduction in the first and second line patterns is reduced, and the side wall protective film due to obliquely incident ions is reduced. The etching effect is reduced, and the dimension reduction amount of the second line pattern is smaller than the dimension reduction amount of the first line pattern.

In the fourth dry etching method, it is preferable that the parameter control step includes a step of reducing a gas pressure of a source gas introduced into the vacuum chamber.

In this way, since the gas pressure of the source gas introduced into the vacuum chamber is reduced, obliquely incident ions are reduced, and the etching effect of the obliquely incident ions on the side wall protective film is reduced. Since the reduction of the etching effect on the sidewall protection film is remarkable in the second line pattern, the dimension reduction amount of the second line pattern is smaller than the dimension reduction amount of the first line pattern.

[0090]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A parallel plate type reactive ion dry etching apparatus as an example of a dry etching apparatus used in the present invention will be described below.

FIG. 1 shows a schematic configuration of a parallel plate type reactive ion dry etching apparatus. As shown in FIG.
A reactive gas is introduced through the chamber 2, and the inside of the chamber 11 is controlled to an appropriate pressure by an exhaust system 13.

An anode (anode) 14 is provided at the upper part of the chamber 11, and a sample stage 15 serving as a cathode (cathode) is provided at the lower part. The sample table 15 is connected to a high-frequency power supply source 17 for supplying high-frequency power via an impedance matching circuit 16, so that high-frequency discharge can be generated between the sample table 15 and the anode electrode 14. The frequency of the high frequency supplied from the high frequency power supply 17 can be changed by the frequency control circuit 21.

The ion energy distribution and the width of the sheath region near the sample table 15 can be determined by the plasma parameter detector 26, and the end point of the etching can be determined by the etching end point detector 20 using a spectral method. . Further, the gas controller 12 and the exhaust system 13 are controlled by a signal from the etching end point detector 20, and the gas pressure and the exhaust amount in the chamber 11 are appropriately controlled. Further, the frequency of the high-frequency power source 17 is controlled via a frequency control circuit 21 by a signal from the etching end point detector 20.

By controlling the heater 23 through the temperature control circuit 24, the temperature of the sample table 15 can be adjusted. Further, the external parameter control device 22 controls the signal from the plasma parameter detector 26 and the signal from the etching end point detector 20, or the values of these signals and the external parameters such as frequency, gas pressure, high frequency power, and sample stage temperature. The gas controller 12, the exhaust system 13, the frequency control circuit 21, and the temperature control circuit 24 can be controlled on the basis of a combination of the above-described signals or a combination of these signals and a previously programmed processing flow.

In the plasma generation region surrounded by the anode electrode 14 and the sample table 15, the anode electrode 14
The region excluding the sheath region near the sample table 15 is generally called a bulk plasma region.

FIG. 2 shows that in the parallel plate type reactive ion etching apparatus shown in FIG. 1, ions starting from the boundary between the bulk plasma region and the sheath region are accelerated toward the sample table 15 between the sheath width d. While the ions are being transported onto the sample stage 15 while they are being scattered, the ions are scattered by collision with neutral particles, so that the directionality of the ions is disordered and the energy of the ions is attenuated.

For the same frequency, collision scattering between ions and neutral particles is smaller in a high vacuum where the gas pressure is low than in a low vacuum where the gas pressure is high.
The high ion flux is more perpendicularly incident on the sample stage 15 due to the high energy. On the other hand, collision and scattering of ions and neutral particles occur more frequently in a low vacuum where the gas pressure is high than in a high vacuum where the gas pressure is low, so that the ion flux density is reduced and the ion energy is reduced. Decreased,
The distribution of the angle of incidence of ions on the sample table 15 is widened.

At the same gas pressure, the collision between ions and neutral particles occurs at a relatively high frequency where the sheath width d is shorter than at a relatively low frequency where the sheath width d is long. Since scattering is reduced, a high ion flux is more perpendicularly incident on the sample stage 15 with high energy. On the other hand, collision and scattering of ions and neutral particles occur more frequently at a relatively low frequency where the sheath width d is long than at a relatively high frequency where the sheath width d is short. Is reduced, the energy of the ions is reduced, and the distribution of the incident angles of the ions on the sample stage 15 is widened.

FIGS. 3 to 10 show the parallel plate type reactive ion etching apparatus shown in FIG. 1, starting from the boundary between the bulk plasma region and the sheath region, being accelerated by the electric field in the sheath region and having neutral particles. The ion angle distribution obtained by integrating the energy Ei and the angular energy distribution f ([theta], _Ei ) of the ions as a function of the angle [theta _] and the energy [theta] of the chlorine ions Cl ^<+> arriving at the wafer surface on the sample stage 15 during the collision. The solid line represents the ion energy distribution h (E _i ) obtained by integrating g (θ) and the angular energy distribution f of the ions in the angular direction. The ion angle θ is an angle measured from a direction perpendicular to the wafer surface. 3A to 10, (a) shows an ion angle distribution, and (b) shows an ion energy distribution. However, sheath width _Lsh = 1 cm, voltage between sheaths = 200 V,
Gas pressure P = 0.1 to 10 Pa.

As can be seen from FIGS. 3 to 10, when the gas pressure is 0.1 Pa or 0.2 Pa, the angular distribution is almost concentrated around 0 degrees, that is, in the vertical incidence state, and the scattering other than 0 degrees is scattered. The components are very small, and the energy distribution is almost concentrated around the sheath-to-sheath voltage of 200 V, and the low-energy components decelerated by scattering are very few.

As the gas pressure is increased from 0.5 Pa to 2 Pa, the scattering component rapidly increases. The peak near 200 V corresponding to the voltage between the sheaths gradually decreases, and conversely, the low energy component decelerated by scattering increases relatively.

When the gas pressure is increased from 5 Pa to 10 Pa, the scattering component in the ion angle distribution certainly increases, but the scattering component is not so different from the case where the gas pressure is 2 Pa. On the other hand, in the ion energy distribution, the peak around 200 V disappears, and the center of the energy distribution moves to the lower energy side.

In FIG. 3 to FIG. 10, the angle distribution curve g ^* (θ) shown by a broken line is a weight of the reaction yield y (number of sputtered Si atoms / number of incident ions) by Cl ⁺ beam depending on the energy. This is obtained by multiplying the ion angular energy distribution f and integrating the result in the energy direction. That is, the angle distribution curve shows that even if the ions are incident on the wafer at the same angle θ, the effect on the etching is different between the ions having the energy of 50 eV and the ions having the energy of 100 eV. An attempt is made to draw an effective angle distribution curve incorporating the influence. Here, the incident energy E _i of the beam is e
It is in V units. Specifically, the incident energy E _i (e
V) corresponds to the inter-sheath voltage Vs (V).

As can be seen from FIGS. 3 to 10, ions having a large scattering angle component generally have a reduced reaction yield weight y (E _i ) because the energy Ei is attenuated. As a result, the spread of the angle distribution of the ion angle distribution indicated by the broken line in consideration of the weight of the reaction yield y is smaller than that of the ion angle distribution g which is simply integrated with respect to energy.

FIG. 11 summarizes the standard deviation σ assuming a normal distribution representing the spread of the scattering angle in the ion angle distribution shown in FIGS. The standard deviation σ of the ion angle distribution increases as the gas pressure increases. That is, the ion angle distribution is
As the gas pressure increases, it gradually expands from vertical incidence. When the gas pressure becomes 2Pa or less,
As the gas pressure decreases, the standard deviation σ sharply decreases almost logarithmically. On the other hand, when the gas pressure is 2 Pa or more,
Even when the gas pressure increases, the standard deviation σ is almost saturated, and the rate of increase is gentle. These changes correspond to changes in the mean free path λ of the ions shown at the same time. Standard deviation σ
Is approximately 10 degrees when the gas pressure is 0.1 Pa, approximately 24 degrees when the gas pressure is 1 Pa, and approximately 27 degrees when the gas pressure is 10 Pa.

It can be understood that when the plasma internal parameters other than the gas pressure are kept constant, the spread of the ion angle distribution can be controlled to some extent by changing the gas pressure at around 1 Pa.

The standard deviation σ of the ion angle distribution was evaluated. As can be understood from FIGS. 3 to 10, the ion angle distribution is different from a so-called normal distribution curve. In this sense, in order to more intuitively grasp the characteristics of the ion angle distribution, consider a certain finite scattering angle width Δ (degree),
A peaking ratio R which is a ratio of the number of ions having a scattering angle smaller than the scattering angle width Δ to the number of all ions.
Evaluate (Δ).

FIG. 12 summarizes the peaking ratio R (Δ) in the ion angle distribution shown in FIGS. 3 to 10 with the gas pressure as the horizontal axis. The peaking ratio R (Δ) increases as a result of reduced ion scattering with decreasing gas pressure. As with the change in standard deviation σ, especially when the gas pressure is 2P
In the case of a or less, the peaking ratio R (Δ) increases significantly with a decrease in the gas pressure. On the other hand, when the gas pressure is 2 Pa or more, the peaking ratio R (Δ) is substantially saturated, and the peaking ratio R (Δ) decreases gradually with an increase in the gas pressure. In FIG. 12, a black symbol is a case where the weight of the reaction yield y is considered, and a white symbol is a case where the weight of the reaction yield y is not considered. Hereinafter, a case in which the weight of the reaction yield y is considered will be described.

Consider a case where the gas pressure is 1 Pa. For example, the relative ratio of ions within the range of the scattering angle width Δ = ± 1 degree, that is, the peaking ratio R (Δ = 1 °) at which the ions reach the wafer with almost no collision with neutral particles
Is about 17%, and the relative peaking ratio R (Δ = 5 °) of ions in the range of the scattering angle width Δ = ± 5 degrees is about 30%. When the gas pressure is 0.1 Pa, the relative peaking ratio R (1 °) of the ions in the range of the scattering angle width Δ = ± 1 degree is about 82%, and the scattering angle width Δ = The relative peaking ratio R (5 °) of the ions falling within the range of ± 5 degrees sharply increases to about 86%.

If the gas pressure P is 0.2 Pa or less,
The ion angle distribution is in a substantially normal incidence state, and the scattering components other than 0 degree are very small. Gas pressure from 0.5Pa to 2
As the pressure is increased to Pa, the scattering component increases significantly. When the gas pressure P is increased from 5 Pa to 10 Pa, the scattering component certainly increases, but there is not much difference as compared with the case where P = 2 Pa.

If the gas pressure P is 0.2 Pa or less,
The ion energy distribution is 200 corresponding to the voltage between the sheaths.
It is almost concentrated near V, and the low energy component decelerated by scattering is very small. When the gas pressure is increased from 0.5 Pa to 2 Pa, 20
The peak near 0 V gradually decreases, and conversely, the low energy component decelerated by scattering relatively increases.
When the gas pressure is increased from 5 Pa to 10 Pa, 20
The peak near 0 V disappears, and the center of the energy distribution moves steadily toward the lower energy side.

In general, incident ions having a large scattering angle component also have attenuated energy E _i, so that the reaction yield y
Is also smaller. As a result, the spread of the angle distribution of the ion angle distribution in consideration of the weight of the reaction yield y is smaller than that of the ion angle distribution simply integrated in the energy direction. When considering the influence on the etching, the ion angle distribution in consideration of the weight of the reaction yield y has more significance.

The standard deviation σ of the angular distribution increases as the gas pressure increases. That is, the angle distribution gradually expands from the normal incidence state as the gas pressure increases. When the gas pressure is 2 Pa or less, the standard deviation σ increases almost logarithmically as the gas pressure increases. On the other hand, when the gas pressure is 2 Pa or more, the standard deviation σ is substantially saturated, and the rate of increase is moderate. These changes correspond to changes in the mean free path λ of the ions. The standard deviation σ is about 10 degrees when the gas pressure is 0.1 Pa, and is about 24 degrees when the gas pressure is 1 Pa,
It can be seen that the gas pressure is about 27 degrees when the pressure is 10 Pa.

To summarize the above results, the sheath width was set to 1c
When the gas pressure is set to m, the point at which the gas pressure becomes 2 Pa is almost at the boundary, and below that point, the collision frequency with the neutral particles of the ions sharply decreases, so that the ion energy distribution h becomes a value corresponding to the voltage between the sheaths. As a result, the ion angle distribution g is in a substantially perpendicular incident state in which the scattering components other than 0 degrees are very small.
On the other hand, when the gas pressure is 2 Pa or more, the decelerated low-energy component relatively increases, and the normal incidence component relatively decreases.

It should be noted that the spread of the ion angle distribution can be controlled to some extent by changing the gas pressure around 1 Pa under the condition that the parameters inside the plasma other than the gas pressure are kept constant. This suggests a possibility for control of a flexible etching shape in this gas pressure region.

The results shown in FIGS. 3 to 12 are quantitatively different if the voltage applied to the electrodes, boundary conditions such as walls, and the type of gas used are changed. However, qualitatively, the above tendency is almost reproduced.

Next, the frequency f of the high-frequency power and the gas pressure P
The above relationship centering on the combination of the two external operating parameters will be described.

That is, the sheath width d on the cathode side formed in the vicinity of the sample table 15 is as follows: d = K ₁ / (P ^m · f ⁿ ) (where K ₁ is a constant) where m is positive. Where n is a positive real number that is greater than approximately 1/3 and less than approximately 1/2, and n is a positive real number that is greater than approximately 1/2 and less than approximately 1. This is because K. Harafuji, A. Yamano and M. Kubota: Jpn. J. App
l. Phys. vol.33 (1994) p2212, and N. Mutsukura, KK
obayashi and Y. Machi: J. Appl. Phys. vol. 68 (1990)
This has already been explained on p.2657.

Further, the mean free path λ of ions mainly derived from elastic collision scattering and charge exchange scattering between ions and neutral particles is inversely proportional to the gas pressure P, and can be expressed as follows. That is, λ = K ₂ / P (where K
₂ is a constant. Further, the probability that ions starting from the boundary between the bulk plasma region and the sheath region are scattered by collision with neutral particles in the sheath region while being transported onto the sample stage 15 serving as the cathode electrode. The quantity η is η
= D / λ. Therefore, by substituting the expressions of d and λ into the expression of η, η = d / λ = (K ₁ / (P ^m · f ⁿ )) × (P / K ₂ ) = (K ₁ / K ₂ ) × (P ^1−m / f ⁿ ) to (K ₁ / K ₂ ) × (P / f) ^1/2

That is, when the gas pressure P and the frequency f are increased, the sheath width d, which is the distance traveled while the ions starting from the boundary between the bulk plasma region and the sheath region travel while being transported onto the sample table 15, becomes shorter. . From this viewpoint, the scattering probability due to collision of ions with neutral particles is reduced.

When the gas pressure P is increased, the mean free path λ of ions is shortened, so that the probability of scattering of ions by collision with neutral particles is increased. Accordingly, by lowering the gas pressure P and increasing the frequency f to reduce P / f, the probability of scattering of ions in the sheath region due to collision with neutral particles can be reduced. Accordingly, the ion energy can be suppressed from being attenuated, and the ions can be made to be almost perpendicular to the sample stage 15 with uniform directionality, so that the attenuation of the ion flux density reaching the sample stage 15 can be suppressed. In addition, it is possible to improve the etching throughput and achieve sufficient etching anisotropy.

When the gas pressure P and the frequency f are reduced, the sheath width d is increased, so that the probability of scattering of ions due to collision with neutral particles is increased. When the gas pressure P is lowered, the mean free path λ of ions becomes longer. For this reason, the scattering probability due to the collision of ions with neutral particles is reduced.
Therefore, by increasing the gas pressure P and decreasing the frequency f, P
By increasing / f, the probability of scattering of ions in the sheath region due to collision with neutral particles can be increased. As a result, the ion energy is attenuated, and the directionality of the ions is made slightly disordered, so that the sample stage 15
, The ion flux density reaching the sample stage 15 can be attenuated, so that the etching ability can be reduced.

The amount of the side wall protective film deposited on the side walls of the pattern due to the reaction product radicals in the chamber is larger in the isolated line pattern (or the outer line pattern) than in the inner line pattern regardless of the gas pressure in the chamber. There are many. Further, the change amount of the deposited amount of the side wall protective film with respect to the change in the ratio of the reaction product radical in the chamber is larger in the side wall of the isolated line pattern than in the inner line pattern.

In the middle vacuum region, the effect of scraping the side wall protective film by obliquely incident ions due to the ion collimation effect is larger in the isolated line pattern than in the inner line pattern. The change in the ion incident angle appears as a larger change in the etching amount of the side wall protective film on the isolated line pattern side wall. That is, with respect to the change of the ratio of the reaction product radical and the ion incident angle,
Isolated line patterns are relatively sensitive, and internal line patterns are relatively insensitive.

In the high vacuum region, ions enter the wafer surface with a relatively small scattering angle. Due to this "pseudo-parallel beam effect", the ion flux incident on the side wall of the isolated line pattern is larger than the ion flux incident on the side wall of the internal line pattern, but the difference is not so remarkable as in the medium vacuum region. In particular, the difference in etching ability of the deposited protective film between the isolated line pattern and the internal line pattern is not so different from that in the medium vacuum region. In the case of a high vacuum region, the angle of the incident ions with respect to the pattern side wall is relatively small, and the ratio of ions incident at a large angle on the pattern side wall is also small. For this reason, the ability to etch the deposited protective film on the side wall of the isolated line pattern is smaller in a high vacuum than in a medium vacuum.

As described above, the mechanism is different between medium vacuum and high vacuum, but the profile of the pattern is made vertical and the difference in dimensional change between the line pattern inside the line and space and the isolated line pattern is different. It is one effective measure to control the amount of exhaust gas by controlling the rate of reaction product radicals in the chamber and controlling the amount of deposition of the sidewall protective film. It can be understood.

Next, the above-mentioned relationship centering on the external operation parameter of the temperature of the sample stage 15 will be described.

The adsorption rate of radicals that play a role of protecting the side wall, such as reaction product radicals existing in the chamber 11 and radicals generated from the side wall protecting additive gas, on the pattern side wall is generally determined by the temperature of the pattern side wall (that is, the temperature of the pattern side wall). , The sample temperature) becomes larger. In the case of the isolated line pattern side wall, the expected solid angle with respect to the side wall protecting radical flux which is incident almost isotropically from above the wafer is approximately π / 2, which is sufficiently large. The side wall protecting radical sufficiently reaches the side wall. However, in the case of the inner line pattern side wall, the expected solid angle is considerably smaller,
In particular, when the pattern aspect ratio (the value obtained by dividing the line height of the line and space pattern by the space width) is large, the expected solid angle becomes considerably small. As a result, in order for the sidewall protecting radical to reach the sidewall of the sample to be etched below the internal line pattern, the adsorption and re-emission must be repeated several times on the sidewall of the internal line pattern. At this time, if the temperature of the pattern side wall (that is, the sample temperature) is low, the adsorption rate increases, so that most of the radicals that play the role of protecting the side wall adhere to the side wall of the resist mask on the upper side of the internal line pattern. The radicals do not sufficiently reach the side wall of the sample to be etched below the internal line pattern. On the other hand, if the temperature of the pattern side wall (that is, the sample temperature) is high, the adsorption rate decreases, so that the side wall protecting radical sufficiently reaches the side wall of the sample to be etched below the internal line pattern.

FIG. 13 shows the movement of the side wall protecting radicals 40 which are almost isotropically incident from above the line and space pattern, by comparing the movement of the side wall protection radical 40 with the outer line pattern in which an environment equivalent to the isolated line pattern is established, This is explained by comparing with a line pattern. In FIG. 13, reference numeral 30 denotes a photoresist pattern, 31 denotes a phosphorus-doped polycrystalline silicon film, 32 denotes a thermal oxide film, and 33 denotes a silicon substrate.

At the time of main etching, ions or radicals react with the material to be etched to produce a reaction product, and the ratio of reactive products increases. During over-etching, the proportion of reactive products decreases. That is, since the ratio of the side wall protecting radical in the chamber changes, the method of controlling the size and profile is different.

In this embodiment, a detector for evaluating the ratio of radicals that play the role of protecting the side wall in the plasma, and a detection for evaluating the ion flux and ion energy distribution of the ions that play the role of etching the deposited side wall protective film. A plurality of external control parameters described above can be optimized using signals from a detector and a sheath width detector serving as an evaluation means of an angular distribution of ions.

The chamber 1 for generating plasma
1 is used to determine the end of the main etching, the etching is performed under the above-described main etching conditions until the main etching is completed, and after the main etching is completed, the over-etching is performed. It is programmed so that two-stage etching can be performed automatically so that etching is performed under etching conditions.

Next, a method will be described in which both the isolated line pattern and the internal line pattern have a vertical profile, and the dimensional shift between them with respect to the resist mask is reduced, thereby reducing the dimensional shift difference between the two.

FIG. 14 is a schematic view showing the mechanism of the difference in profile and dimensional change between an internal line pattern and an isolated line pattern in a line-and-space pattern in the parallel plate type reactive ion etching apparatus shown in FIG. The description is divided into a vacuum region and a high vacuum region. In FIG. 14, reference numeral 34 denotes a sidewall protective deposition film of a reaction product or the like, 35 denotes ions, and 36 denotes a decrease in the thickness of the sidewall protective deposition film such as a reaction product etched by the ions 35. It is.

As will be described first from the conclusion, in order to make the profile vertical and to reduce the difference in dimensional change between the internal line pattern and the isolated line pattern in the line and space pattern, the displacement is controlled by: Controlling the proportion of reaction product radicals in the chamber is one effective strategy. In the following, the medium vacuum and the high vacuum do not indicate specific pressures, but are used as expressions expressing the above-described difference in ion angle distribution.

By the way, the amount of the side wall protective film deposited on the side wall of the pattern due to the side wall protective radicals such as reaction product radicals in the chamber is irrespective of the gas pressure in the chamber.
There are more isolated line patterns (or external line patterns) than internal line patterns. The reason is that, as described above, in the case of the isolated line pattern side wall, the expected solid angle with respect to the side wall protecting radical flux incident almost isotropically from above the wafer is approximately π / 2, This is because in the case of the inner line pattern side wall, the expected solid angle is considerably reduced.

As the ratio of the reaction product radicals in the chamber is reduced, the amount of the side wall protective film deposited on the isolated line pattern side wall and the amount of the side wall protective film on the inner line pattern side wall decrease while maintaining a constant ratio. . However, the ratio of the decrease of the sidewall protective film to the decrease of the ratio of the sidewall protective radical is larger in the isolated line pattern sidewall than in the internal line pattern sidewall. That is, the amount of change of the side wall protective film on the side wall of the isolated line pattern is larger than the amount of change of the side wall protective film on the side wall of the internal line pattern.

Hereinafter, the movement of the incident ions in the case of the medium vacuum region will be discussed. In the medium vacuum region, ions enter the wafer surface in a state having a relatively large scattering angle component due to collision with neutral particles in the sheath region. Such obliquely incident ions have an effect of shaving the side wall protective film on the pattern side wall where the amount of the deposited protective film is large, and changing the profile from a forward taper to a vertical one. As the incident angle of ions becomes more perpendicular to the pattern side wall, the etching ability of the side wall protective film increases. Conversely, ions incident perpendicularly to the wafer surface have an incident angle substantially parallel to the pattern side wall, and thus have a small etching capability for the side wall protective film. On the other hand, the obliquely incident ions scrape off the side wall protective film on the pattern side wall with a small deposition amount of the protective film, and lose the protection effect. As a result, the profile is tapered from vertical to reverse.

The above phenomenon is particularly remarkable as a result of the direct collision of the ions with the side walls of the isolated line pattern because the expected solid angle for the obliquely incident ions is large on the side walls of the isolated line pattern. On the other hand, on the side wall of the internal line pattern, the expected solid angle of incidence for obliquely incident ions becomes considerably small, so that incident ions having a scattering angle of a certain size or more do not enter the internal space of the line-and-space pattern. It will be reflected. That is, the ion angle distribution component having a large scattering angle cannot directly fly below the inner line pattern pattern side wall, and only the ion angle distribution component having a relatively small scattering angle that is more perpendicular to the wafer surface. , Can be selectively incident. That is, of the ion flux having a wide ion angle distribution component, only a component at a certain angle or less is collimated, and there is an effect of allowing the internal pattern in the line and space pattern to fly to the lower part of the side wall. This effect is the above-mentioned “ion collimation effect”.

The ions having a large scattering angle which have entered the vicinity of the upper part of the side wall of the internal line pattern cannot enter the lower part of the side wall of the internal line pattern without being reflected several times with the side wall. During this time, the energy of the ions will decrease and the ability to etch the deposited overcoat will decrease. In addition, the incident ion flux naturally decreases as compared with the isolated line pattern.

Hereinafter, the contents described above will be described together.

First, the amount of change in the deposition amount of the side wall protective film with respect to the change in the ratio of the side wall protective radicals in the chamber is larger on the isolated line pattern side wall than on the internal line pattern side wall. In addition, the effect of shaving the side wall protective film by obliquely incident ions is due to the ion collimation effect.
The isolated line pattern side wall is larger than the internal pattern side wall. Then, the change in the ion incident angle appears as a larger change in the etching amount of the side wall protective film on the side wall of the isolated line pattern. That is, the isolated line pattern is relatively sensitive to changes in the ratio of reaction product radicals and the angle of incidence of ions, and the internal line pattern is relatively sensitive to changes in the ratio of reaction product radicals and changes in the angle of incidence of ions. Relatively insensitive.

Next, the movement of the incident ions in the high vacuum region will be described. In a gas pressure region where a high vacuum is applied, ions collide with neutral particles in the sheath region less, many components are incident relatively perpendicularly, and the scattering angle is generally relatively small on the wafer surface. Incident. In other words, in the case of a high vacuum region, many ions are incident in a substantially uniform shape along the pattern side wall.

In the case of such an incident ion angle distribution, the ion flux incident on the side wall of the isolated line pattern is larger than the ion flux incident on the side wall of the internal line pattern, but the difference is as large as in the middle vacuum region. Is not significant. That is, the difference in the etching ability of the deposited protective film between the isolated line pattern and the internal line pattern is not so large as in the case of the middle vacuum region. Further, the angle of the incident ions with respect to the side wall is relatively small, and the ratio of ions incident at a large angle on the side wall is small. For this reason, the ability to etch the deposited protective film is smaller than that in the case of the middle vacuum region, and particularly small on the side wall of the isolated line pattern. On the other hand, the magnitude of the deposited amount of the side wall protective film is larger on the isolated line pattern side wall than on the internal line pattern side wall. This is the "quasi-parallel beam effect" described above.

As described above, in order to make the profile vertical and to reduce the dimensional difference between the internal pattern and the isolated line pattern, the amount of exhaust is increased and the ratio of reaction product radicals in the chamber is reduced. It can be understood that reducing the amount of the deposited side wall protective film is one effective measure. This is because the components of the obliquely incident ions are small and etching of the sidewall protective film by the ions cannot be expected much.

FIG. 15 shows how various internal parameters change when external control parameters such as gas pressure P and displacement Q are changed.

When the gas pressure P is increased, the following internal parameters change. First, the energy Ei of ions incident on the wafer surface decreases. The standard deviation σ of the ion scattering angle, which indicates the spread of the ion angle distribution g of the incident ions, increases. Since an increase in the gas pressure P means an increase in the source gas, as long as the input power is capable of sufficiently ionizing and exciting the source gas, the reactive radical flux F _R and the ion flux _Fi are increased. As a result, the ratio of sidewall protection radicals such as reaction products and sputtered resist in the chamber increases, resulting in an increase in the sidewall protection radical bundle F _RP .

The ion energy E _i and the standard deviation σ of the ion scattering angle are internal parameters related to the etching ability of the deposited amount of the side wall protective film, and a decrease in the ion energy E _i results in a decrease in the etching ability and an ion scattering angle. Since the increase in the standard deviation σ of the above results in an improvement in the etching capacity, it cannot be simply determined whether the increase in the gas pressure P results in the improvement or the decrease in the etching capacity. On the other hand, an increase in the side wall protecting radical bundle F _RP clearly leads to an increase in the amount of side wall protecting film deposition. Therefore, it cannot be simply determined whether an increase in the gas pressure P causes an increase or a decrease in the deposition amount of the sidewall protective film. However, if the gas exhaust amount is increased while the gas pressure P is kept constant, and the ratio of the sidewall protection radical in the chamber is reduced, the etching of the sidewall protection film is superior to the increase in the film deposition amount. Become. That is, by controlling the displacement, the thickness of the sidewall protective film can be controlled.

Let us consider a case where both the profile of the isolated line pattern and the profile of the internal line pattern are forward-tapered under certain process conditions. When there are many side wall protecting radicals in the chamber, generally, the isolated line pattern has a stronger forward taper than the internal line pattern. In such a state, a measure for making the profiles of both of them more vertical and reducing the dimensional difference between them will be described.

By increasing the exhaust amount Q, the etching of the side wall protective film creates a condition that is superior to the increase in the film deposition amount. Consider a case where the deposition amount of the sidewall protective film is relatively large under this condition. In the isolated line pattern, the profile that had a strong forward taper when the displacement was small changed relatively significantly to the vertical profile. In the internal line pattern, the profile that was forward tapered when the displacement was small was compared with the profile. It gradually changes from a weak taper to a vertical profile.

On the other hand, let us consider a case where the deposition amount of the side wall protective film is relatively small under the condition that the etching of the side wall protective film is superior to the increase of the film deposition amount. In the isolated line pattern, the profile that was forward-tapered when the displacement was small changed to reverse taper, and in the internal line pattern, the profile that was forward-tapered when the displacement was small compared to the weak taper to the vertical profile It changes slowly.

That is, as described above, the side wall of the isolated line pattern is more than the side wall of the internal line pattern.
Since the amount of deposition of the sidewall protective film decreases greatly with respect to the decrease in the ratio of the sidewall protective radicals in the chamber with the increase in the exhaust amount, the etching effect of the sidewall protective film due to an increase in the finite standard deviation σ appears significantly. With these effects,
When the displacement is small, the dimensional difference between the isolated line pattern and the internal line pattern can be reduced.

The effects of increasing the exhaust amount Q while keeping the gas pressure in the chamber constant will be summarized below. First,
Even if the displacement Q is increased, the ion energy E _i and the standard deviation σ of the ion scattering angle do not change, so that the ability to etch the sidewall protective film does not change. On the other hand, since the amount of sidewall protection radicals decreases, the amount of film deposition decreases, and the sidewall protection film etching effect due to an increase in the standard deviation σ of the finite ion scattering angle greatly appears.

[0154] Figure 16 is a various internal parameters when changing the external operating parameters of the bias power W _B showed how the changes.

[0155] Increasing the bias power W _B, can be considered a change in internal parameters such as the following. First, the energy E _i of the ions incident on the wafer surface will increase. Furthermore, an increase in the bias power W _B, since means an increase of the ionization excitation of the raw material gas in the vicinity of the wafer surface, would result in an increase in ion flux F _i and the reactive radical flux F _R. As a result, the ratio of sidewall protection radicals such as reaction products and sputtered resist in the chamber increases, resulting in an increase in the sidewall protection radical bundle F _RP .

The ion energy E _i , the ion flux F _i, and the standard deviation σ of the ion scattering angle are internal parameters related to the etching ability of the deposited amount of the sidewall protective film. An increase in the ion energy E _i and the ion flux F _i leads to an improvement in the etching ability. On the other hand, the standard deviation σ of the ion scattering angle
And the increase in the sidewall protection radical flux F _RP results in an increase in the sidewall protection film deposition amount. Therefore, the bias power W _B
It cannot be simply determined whether the increase in the amount results in an increase or decrease in the amount of deposited sidewall protective film. However, while maintaining a bias power W _B constant, the exhaust amount increases, if tried to decrease the proportion of the side wall protective radicals, etching of the sidewall protective film comes to over the increase in the film deposition amount. That is, the sidewall protective film thickness can be controlled by controlling the displacement.

It is assumed that, under certain process conditions, there are many side wall protecting radicals in the chamber, and both the profile of the isolated line pattern and the profile of the internal line pattern are forward tapered. Generally, an isolated line pattern has a stronger forward taper than an internal line pattern. In such a state, a measure for making the profiles of both of them more vertical and reducing the dimensional difference between them will be considered.

Considering a 2 × 2 matrix as shown in the table of FIG. 16 for the case of low displacement and high displacement, and for the case of medium vacuum and high vacuum, the bias power W _{B in} each case is considered. Let us consider how the profile of the isolated line pattern and the internal line pattern changes when is increased.

In the case of a medium vacuum and a low pumping amount, it is not clear whether the profile of the isolated line pattern has a forward taper or a reverse taper because of the mutual competition. That is, when the bias power W _B is increased, the ion energy E result in an increase in the sidewall protective film etching
_{Although i} and the ion flux F _i increase, it is considered that the increase in the deposition amount of the sidewall protective film is also large. The profile of the internal line pattern has a smaller etching ability than that of the isolated line pattern.

In the case of a medium vacuum and a high displacement, a so-called "ion collimation effect" works. In the isolated line pattern, as a result of the sidewall protection film being etched more, the taper changes from a forward taper to a reverse taper.
On the other hand, in the internal line pattern, the etching amount of the side wall protective film is not so large, for example, it changes from a forward taper to a weak forward taper. That is, by increasing the bias power W _B, towards the isolated line pattern having a large size reduction amount than the internal line pattern pattern comes thinned.

In the case of a high vacuum and a low pumping amount, the so-called “pseudo parallel beam effect” works, so that the etching ability of the sidewall protective film becomes small, and the difference in etching ability between the isolated line pattern and the internal pattern becomes small. Become. However, the deposited amount of the sidewall protective film itself is larger in the isolated line pattern than in the internal line pattern. Therefore, if the isolated line pattern has a forward taper,
The internal line pattern has a weak forward taper. That is,
The increase in the bias power W _B, increasing the sidewall protection radicals in the chamber, towards the isolated line pattern comes fatter than the internal line pattern.

The "pseudo-parallel beam effect" also works in the case of a high vacuum and a high displacement. The etching ability of the side wall protective film is larger than that in the case of a low displacement. The difference in etching ability between the isolated line pattern and the internal pattern is small. The deposition amount of the sidewall protective film itself is thin due to the high exhaustion amount, and the deposition amount of the isolated line pattern is larger than that of the internal line pattern. Therefore, the bias power W _B
If the isolated line pattern changes from a forward taper to a weak forward taper due to the increase in the number, the internal line pattern changes from a weak forward taper to a reverse taper. By an increase in bias power W _B, towards the inside line pattern comes thinned than the isolated line pattern.

FIG. 17 summarizes the method of reducing the dimensional difference between the isolated line pattern and the internal line pattern, that is, the method of reducing the dependence of the size on the aperture ratio, in the case of medium vacuum.

In this case, the etching ability of the sidewall protective film due to the finite effect of the standard deviation σ of the ion angle distribution positively exerts the “ion collimation effect” that the isolated line pattern is larger than the internal line pattern. Used. When the isolated line pattern has a stronger forward taper profile than the internal line pattern and has a larger size, the amount of exhaust gas is increased or the ratio of gas generating the sidewall protecting radical is reduced. Thereby, the side wall protection radical in the chamber decreases, and the amount of the side wall protection film decreases. Then, the etching effect of the sidewall protective film due to the finite effect of the standard deviation σ of the ion angle distribution is relatively increased. In this manner, the isolated line pattern has a larger dimension reduction than the internal line pattern, and the intended purpose can be achieved.

Next, when the size of the isolated line pattern is smaller than that of the internal line pattern, the amount of exhaust gas is reduced or the ratio of the gas generating the sidewall protecting radical is increased. Thereby, the side wall protection radical in the chamber increases, and the amount of the side wall protection film increases. The phenomenon that the increase in the sidewall protective film exceeds the amount of etching the sidewall protective film due to the finite effect of the standard deviation σ of the ion angle distribution with the increase in the sidewall protective radical ratio is due to the fact that the isolated line pattern has Since the line pattern is larger than the line pattern, the isolated line pattern has a larger dimension increase than the internal line pattern, and the intended purpose can be achieved.

[0166] To further increase the finite effect of the standard deviation of the ion angular distribution σ, while slightly increasing the gas pressure, may a little larger bias power W _B. This is because when is pressurized the gas pressure energy E _i of the ions is reduced, in order to compensate for this.

FIG. 18 summarizes a method of reducing the dependence of the size on the aperture ratio in the case of high vacuum. In this case, the slightly obliquely incident ion flux has little difference in the etching ability of the sidewall protective film for the isolated line pattern and the internal line pattern, and the deposition amount of the sidewall protective film is small. The "pseudo-parallel beam effect" that the isolated line pattern is larger than the internal line pattern is positively used.

First, when the isolated line pattern has a stronger forward taper profile and a larger dimension than the internal line pattern, the amount of exhaust gas is increased or the ratio of the gas generating the sidewall protecting radical is reduced. Thereby, the side wall protection radical in the chamber decreases, and the amount of the side wall protection film decreases. By utilizing the fact that the reduction rate of the sidewall protective film is larger in the isolated line pattern than in the internal line pattern, the intended purpose can be achieved. Conversely, when the isolated line pattern is thinner than the internal line pattern, the amount of exhaust gas is reduced or the ratio of the gas that generates the sidewall protecting radical is increased.

FIG. 19 shows a method of reducing the dependence of the size on the aperture ratio in each case in the 2 × 2 matrix in consideration of the case of medium vacuum and high vacuum for the isolated line pattern and the internal line pattern. Is a summary of the first steps to take. The case where the isolated line pattern and the internal line pattern have a forward taper and a reverse taper with respect to a certain process condition are shown as being divided into eight types (A) to (H).

FIG. 20 shows what measures should be taken thereafter in each of the cases (E)-(H) in FIG. 19 to make the dimensional difference between the isolated line pattern and the internal pattern satisfy the condition. It is shown in the form of a case study.

For example, under the high vacuum condition of the case (H),
The case where the internal line pattern becomes reverse tapered under a certain process condition will be described. In this case, it is assumed that the isolated line pattern has a vertical profile. As a result of performing the processing shown in case (H), the internal line pattern may become vertical and the isolated line pattern may become slightly tapered (the state shown by (H-1)). If this state satisfies the dimensional difference requirement standard, the determination is OK and the processing is terminated. If the degree of the forward taper, that is, the dimension of the isolated line pattern is too large, the displacement Q is slightly increased (the measure indicated by (H-2)). If so, the internal line pattern will have a slight reverse taper, the degree of forward taper of the isolated line pattern will decrease, and may meet the dimensional difference requirements (state indicated by (H-3)). If the dimensional difference requirement standard is still not satisfied, the displacement is increased while the gas pressure P is slightly increased, thereby increasing the etching effect of the sidewall protective film which causes the forward taper of the isolated line pattern ((H− 4)). By repeating such a process, a process condition satisfying the dimensional difference requirement standard is determined.

Hereinafter, an example of the case where the etching process conditions are improved in the main etching operation mode using the parallel plate type reactive ion etching apparatus by the above-described method is schematically described for forming a phosphorus-doped polycrystalline silicon gate. Shown in

FIG. 21 is a diagram showing a pattern configuration before etching. In FIG. 21, reference numeral 30 denotes a photoresist pattern, 31 denotes a phosphorus-doped polycrystalline silicon film, 32 denotes a thermal oxide film, and 33 denotes a silicon substrate. As shown in FIG. 21, it is a 0.4 μm line and space pattern, and its cross section has a structure of “1.0 μm thick resist mask + 0.3 μm thick polysilicon film + underlying oxide film”. The resist mask profile has a slight forward taper. Here, etching of the resist itself is not considered. For convenience, the top surface of the resist is a y = 0 plane.

Unless otherwise specified, etching was performed under the following conditions. As a gas to be introduced into the plasma generator chamber, Cl ₂ is introduced by only 40 sccm, the gas pressure P in the etching apparatus is 10 Pa, the frequency f of the high-frequency power is 13.56 MHz, and the gas displacement is 100.
Performed at 0 liter / sec. In each of the examples described below, the bias power, that is, the power of the high-frequency power is appropriately changed for operation. Use of a gas based on another halogen-based gas such as HBr or SF ₆ is also sufficiently effective.

FIGS. 22 to 35 show specific embodiments. 22 to 35, 30 is a photoresist pattern, 31 is a phosphorus-doped polycrystalline silicon film, 3
Reference numeral 4 denotes a deposited film of a sputtered photoresist or a reaction product of silicon and a halogen-based gas.

FIG. 22 to FIG.
The structure of the surface of the polycrystalline silicon film 31 which has been etched for 15 times in a second step for a total of 30 seconds is shown. That is, in FIGS. 22 to 35, one surface string represents the surface shape at a certain time. There are 15 surface strings, each representing the change in surface shape over time. In addition, the height of the surface of the photoresist pattern is set to 0, and the unit is μm. 22A to 35A show the state before the improvement, and FIG. 22B shows the state after the improvement.

FIG. 22 (a) shows the result of etching with Cl ₂ introduced at a flow rate of 40 sccm, a gas pressure of 10 Pa and medium vacuum, and an exhaust rate of 1000 liter / sec. As described above, the isolated line pattern has a larger deposition amount of the side wall protective film than the internal line pattern, and the pattern profile after etching has a forward taper and a larger size. FIG. 22 (b)
With the gas pressure kept constant at 10 Pa,
The result shows that the amount of the protective film on the side wall of the pattern is reduced due to a decrease in the protective radical on the side wall in the chamber, and the etching effect of the protective film on the side wall by obliquely incident ions is relatively increased. As shown in the figure, the isolated line pattern has a larger dimension reduction amount than the internal line pattern, the profiles of the isolated line pattern and the internal line pattern become more vertical,
The dimensional difference between the isolated line pattern and the internal line pattern has been reduced.

FIG. 23A shows that Cl ₂ is introduced at a rate of 40 sccm, SiCl ₄ as a side wall protecting radical is introduced at a rate of 20 sccm, the gas pressure is set to 10 Pa and the vacuum is increased to 1500 liter / second. As shown in the figure, the isolated line pattern has a larger amount of deposited sidewall protective film than the internal line pattern, the pattern profile after etching has a forward taper, and the dimensions are smaller. Is fat. FIG. 23 (b) shows a gas pressure of 10 Pa and a displacement of 1500
While maintaining a constant rate of 1 liter / sec, 10 seconds of SiCl ₄
shows the result of the reduction to ccm, the side wall protection radical in the chamber is reduced, the amount of protection film on the pattern side wall is reduced,
Since the etching effect of the side wall protective film by the obliquely incident ions becomes relatively large, as shown in the same figure, the dimensional reduction amount of the isolated line pattern is larger than that of the internal line pattern. The profile of the pattern has become more vertical, and the dimensional difference between the isolated line pattern and the internal line pattern has been reduced.

FIG. 24 (a) shows the result of etching with Cl ₂ introduced at a flow rate of 40 sccm, a gas pressure of 8 Pa, medium vacuum, and an exhaust rate of 1000 l / sec. As described above, the isolated line pattern has an inversely tapered pattern profile after etching and a smaller dimension than the internal line pattern. FIG. 24 (b) shows the result of reducing the exhaust volume to 500 liter / sec while keeping the gas pressure constant at 8 Pa. As the etching effect of the sidewall protective film due to the obliquely incident ions becomes relatively small, as shown in FIG. The profile of the internal line pattern has become more vertical, and the dimensional difference between the isolated line pattern and the internal line pattern has been reduced.

FIG. 25 (a) shows that etching was carried out by introducing Cl ₂ at only 40 sccm and SiCl ₄ at only 15 sccm, setting the gas pressure at 10 Pa and a medium vacuum, and exhausting at a rate of 1000 liter / second. The results show that, as shown in the figure, the isolated line pattern has a pattern / etch
The profile is reverse tapered and narrow in size. FIG. 25 (b) shows a gas pressure of 10 Pa and a displacement of 1
The result shows that the SiCl ₄ was increased to 25 sccm while keeping constant at 2,000 liters / sec., The side wall protection radical in the chamber increased, the amount of the protection film on the pattern side wall increased, and the side wall protection film by obliquely incident ions increased. Since the etching effect is relatively small, as shown in the figure, the size increase of the isolated line pattern is larger than that of the internal line pattern, and the profiles of the isolated line pattern and the internal line pattern are more vertical. , The dimensional difference between the isolated line pattern and the internal line pattern is reduced.

FIG. 26 (a) shows the result of etching with Cl ₂ introduced at a flow rate of 40 sccm, a gas pressure of 4 Pa, a high vacuum, and an exhaust rate of 1000 l / sec. As described above, the isolated line pattern has a larger deposition amount of the side wall protective film than the internal line pattern, and the pattern profile after etching has a forward taper and a larger size. FIG. 26 (b)
With the gas pressure kept constant at 4 Pa,
The result of the increase to 0 liter / sec shows that the side wall protection radical in the chamber is reduced, the amount of the protection film on the pattern side wall is reduced, and the etching effect of the side wall protection film by obliquely incident ions is relatively increased. As shown in the drawing, the size reduction of the isolated line pattern is larger than that of the internal line pattern, the profiles of the isolated line pattern and the internal line pattern are more vertical, and the distance between the isolated line pattern and the internal line pattern is larger. Dimensional difference has decreased.

FIG. 27 (a) shows that Cl ₂ is introduced only at 40 sccm, SiCl ₄ is introduced at only 20 sccm, the gas pressure is set at a high vacuum of 4 Pa, and the exhaust amount is set at 1.
The result of etching at 000 liters / sec shows that the isolated line pattern has a larger deposition amount of the side wall protective film than the internal line pattern, and the pattern profile after etching has a forward taper and a large size. I have. FIG. 27 (b) shows that the SiCl was kept at a constant gas pressure of 4 Pa and a constant displacement of 1000 liter / sec.
₄ was reduced to 10 sccm, and the side wall protection radical in the chamber was reduced, the amount of protection film on the pattern side wall was reduced, and the etching effect of the side wall protection film by obliquely incident ions became relatively large. As shown in the drawing, the size reduction amount of the isolated line pattern is larger than that of the internal line pattern, and the profiles of the isolated line pattern and the internal line pattern become more vertical,
The dimensional difference between the isolated line pattern and the internal line pattern has been reduced.

FIG. 28 (a) shows the result of etching with Cl ₂ introduced at a flow rate of 40 sccm, a gas pressure of 4 Pa, a high vacuum, and an exhaust rate of 1000 l / sec. As described above, the isolated line pattern has an inversely tapered pattern profile after etching and a smaller dimension than the internal line pattern. FIG. 28 (b) shows the result of reducing the exhaust rate to 500 liter / sec while keeping the gas pressure constant at 4 Pa. The side wall protecting radical in the chamber increases, and the amount of the protective film on the pattern side wall decreases. As the etching effect of the sidewall protective film due to the obliquely incident ions becomes relatively small, the isolated line pattern has a larger dimensional increase than the internal line pattern as shown in FIG. The profile of the internal line pattern has become more vertical, and the dimensional difference between the isolated line pattern and the internal line pattern has been reduced.

FIG. 29 (a) shows that the etching is carried out by introducing Cl ₂ at only 40 sccm, introducing SiCl ₄ at only 15 sccm, setting the gas pressure to a high vacuum of 4 Pa, and evacuating the gas at a rate of 1000 liter / sec. As shown in the figure, the isolated line pattern has a pattern and an etched pattern which are better than the internal line pattern.
The profile is reverse tapered and narrow in size. FIG. 29 (b) shows a gas pressure of 4 Pa and a displacement of 10
00 while maintaining constant in liters / sec., The SiCl ₄ 2
The result of the increase to 5 sccm shows that the side wall protection radical in the chamber increases, the amount of the protection film on the pattern side wall increases, and the etching effect of the side wall protection film by obliquely incident ions becomes relatively small. As shown,
The size increase of the isolated line pattern is larger than that of the internal line pattern, the profiles of the isolated line pattern and the internal line pattern are more vertical, and the dimensional difference between the isolated line pattern and the internal line pattern is reduced. I have.

FIG. 30 (a) shows that Cl ₂ was introduced at a flow rate of 40 sccm, the gas pressure was set at a medium vacuum condition of 10 Pa, the exhaust amount was 1000 liter / second, and the bias power was 30.
The result of etching at 0 watts is shown. As shown in the figure, the isolated line pattern has a larger amount of deposited sidewall protective film than the internal line pattern, and the pattern profile after etching has a forward taper. And the dimensions are fat. FIG. 30B shows that the displacement is 1000
The gas pressure is maintained at 15 Pa while maintaining a constant
And the bias power was increased to 400 watts, as shown in the figure. As shown in the figure, the spread of the angular distribution of ions became large, and the decrease in ion energy with the increase in gas pressure was caused by the bias power. And the etching effect of the sidewall protective film by the obliquely incident ions becomes relatively large, so that the isolated line pattern has a larger dimensional reduction than the internal line pattern, and the isolated line pattern and the internal line pattern Has become more vertical, reducing the dimensional difference between the isolated line pattern and the internal line pattern.

FIG. 31 (a) shows that Cl ₂ was introduced at a flow rate of 40 sccm, the gas pressure was set at a medium vacuum of 10 Pa, the exhaust amount was 1000 liter / second, and the bias power was 30.
The result of etching at 0 watts is shown. As shown in the figure, the isolated line pattern has a larger amount of deposited sidewall protective film than the internal line pattern, and the pattern profile after etching has a forward taper. And the dimensions are fat. FIG. 31 (b) shows a gas pressure of 15 P while keeping the bias power constant at 300 watts.
The results show that the exhaust gas volume was increased to 2000 liters / sec along with the increase in the ion beam width, and the spread of the angular distribution of ions increased, the amount of deposited sidewall protective film decreased, and the etching effect of the sidewall protective film due to obliquely incident ions was reduced. Due to the relative increase, as shown in the drawing, the isolated line pattern has a larger dimension reduction than the internal line pattern, and the profiles of the isolated line pattern and the internal line pattern become more vertical, and the isolated line pattern becomes The dimensional difference between the pattern and the internal line pattern has been reduced.

FIG. 32 (a) shows that Cl ₂ was introduced at a flow rate of 40 sccm, the gas pressure was set to a high vacuum of 4 Pa, the displacement was 1000 l / sec, and the frequency of the high-frequency power was 1
The result of etching at 3.56 MHz is shown. As shown in the figure, the pattern profile after etching has an inverse taper and a smaller dimension in the isolated line pattern than in the internal line pattern. FIG. 32 (b) shows the result of increasing the frequency of the high-frequency power to 50 MHz while keeping the gas pressure constant at 4 Pa and the displacement at 1000 l / sec. As the ratio becomes smaller, the amount of etching of the protective film particularly on the side wall of the isolated line pattern becomes smaller. As a result, as shown in the figure, the size increase of the isolated line pattern becomes larger than that of the internal line pattern, and the isolated line pattern becomes larger. In addition, the profile of the internal line pattern becomes more vertical, and the dimensional difference between the isolated line pattern and the internal line pattern is reduced.

FIG. 33 (a) shows that Cl ₂ was introduced at a flow rate of 40 sccm, the gas pressure was set to a high vacuum of 4 Pa, the displacement was 800 liter / second, and the frequency of the high-frequency power was 50M.
The results of etching at Hz are shown. As shown in the figure, the pattern profile after etching has a reverse taper and a smaller dimension in the isolated line pattern than in the internal line pattern. FIG. 33 (b)
This shows the result of increasing the frequency of the high-frequency power to 100 MHz while keeping the exhaust rate constant at 800 liters / second, and it is possible to stably reduce the gas pressure at which plasma is generated to 0.5 Pa. As the proportion of incident ions decreases, the etching amount of the protective film particularly on the side wall of the isolated line pattern decreases.
As shown in (b), the size increase of the isolated line pattern is larger than that of the internal line pattern, and the profiles of the isolated line pattern and the internal line pattern are more vertical. The dimensional difference between them has been reduced. Also, set the frequency to 50
Even if the gas pressure was reduced to 2 Pa while keeping the frequency constant at MHz, a sufficient effect was obtained.

FIG. 34 (a) shows the result of etching with Cl ₂ introduced at a flow rate of 40 sccm, a gas pressure of 4 Pa, a high vacuum condition, an exhaust rate of 1000 l / sec, and a sample stage temperature of 30 ° C. And, as shown in FIG.
Isolated line patterns are better than internal line patterns,
The deposition amount of the side wall protective film is increased, and the pattern profile after etching has a forward taper and the size is large. FIG. 34 (b) shows a gas pressure of 4 Pa and a displacement of 10 Pa.
The sample stage temperature was set at 8
The result of the increase to 0 degrees shows that the side wall protection radicals deposited on the side wall of the isolated line pattern are reduced, the amount of the protection film on the pattern side wall is reduced, and the effect of etching the side wall protection film by obliquely incident ions is relatively increased. As a result, as shown in the drawing, the size reduction amount of the isolated line pattern is larger than that of the internal line pattern, the profiles of the isolated line pattern and the internal line pattern become more vertical, and the isolated line pattern and the internal line pattern The dimensional difference between is reduced.

FIG. 35 (a) shows the result of etching with Cl ₂ introduced at a flow rate of 40 sccm, a gas pressure of 10 Pa, medium vacuum, an exhaust rate of 1000 liter / sec, and a sample stage temperature of 30 ° C. As shown in the figure, the isolated line pattern has a smaller deposition amount of the side wall protective film than the internal line pattern, and the pattern profile after the etching has an inverse taper and a smaller size. FIG. 35 (b) shows the result of lowering the temperature of the sample stage to 0 ° C. while keeping the gas pressure constant at 10 Pa and the exhaust volume at 1000 liter / sec. As the radical increases, the amount of protective film on the pattern side wall increases, and the etching effect of the side wall protective film due to obliquely incident ions becomes relatively small, as shown in the figure, the isolated line pattern is larger than the internal line pattern. Also, the dimension increase amount becomes large, the profiles of the isolated line pattern and the internal line pattern become more vertical, and the dimensional difference between the isolated line pattern and the internal line pattern is reduced.

In another embodiment, Cl ₂ is added for 40 seconds.
ccm, and the gas pressure is set to 10 Pa under a medium vacuum condition.
When etching was performed at an exhaust rate of 2000 liters / second and the sample stage temperature was 0 ° C., the deposition amount of the side wall protective film was smaller in the internal line pattern than in the isolated line pattern, and the pattern profile after the etching was reverse-tapered. And the dimensions were small, but as a result of setting the gas pressure to 3 Pa, the components of the obliquely incident ions became small, the profiles of the isolated line pattern and the internal line pattern became more vertical, and the dimensions of the isolated line pattern and the internal line pattern were reduced. The difference could be reduced.

The embodiment shown in FIGS. 22 to 35 is an example in which a measure for improving the process condition is implemented in order to solve the problem when the process is performed under a certain process condition. However, during the etching process, the internal plasma state is not always constant but changes to some extent with time. For this reason, the ion flux density, ion energy, ion incident angle distribution, and side wall protecting radical flux near the sample stage also change to some extent with time. By changing the external parameters by the external parameter control device so as to compensate for such a temporal change, the profiles of the isolated line pattern and the internal line pattern are made more vertical, and the isolated line pattern and the internal line pattern are changed. Could be reduced.

The embodiments shown in FIGS. 22 to 35 are performed in the main etching operation mode.
In the over-etching operation mode in which the underlying oxide film starts to appear, the proportion of the reaction product is reduced, and the proportion of the sidewall protecting radical is also reduced.

FIG. 36 shows a state where etching is performed by switching between the main etching operation mode and the over-etching operation mode using a parallel plate type reactive ion dry etching apparatus in the same manner as described above. The state of the etching performed on the polycrystalline silicon film is shown.

FIG. 36 (a) shows that, in the main etching operation mode, Cl ₂ is introduced by only 40 sccm, the gas pressure is set to a high vacuum of 4 Pa, the displacement is 1000 liter / sec, and the frequency of the high frequency power is 13. The result of etching at 56 MHz is shown. As shown in FIG.
The profiles of the isolated line pattern and the internal line pattern are substantially vertical, and the dimensional difference between the isolated line pattern and the internal line pattern is reduced. FIG.
(B) shows the result of performing over-etching under the above conditions. As shown in the figure, the isolated line pattern has a reverse tapered pattern profile and smaller dimensions than the internal line pattern after etching. ing. FIG. 36 (c) shows a case where the frequency of the high frequency power is set to 50 MHz while the gas pressure is kept constant at 4 Pa and the displacement is kept at 1000 liter / second in order to improve the state of FIG. 36 (b).
The result shows that the sheath width decreases, the ratio of obliquely incident ions decreases, and as shown in the figure, the protective film etching amount on the isolated line pattern side wall decreases,
The profiles of the isolated line pattern and the internal line pattern are more vertical, and the dimensional difference between the isolated line pattern and the internal line pattern is reduced. In this case, in order to increase the etching selectivity with respect to the silicon oxide film, the power of the high frequency power is reduced to 200 W, whereby the voltage between the sheaths is reduced and the energy of ions is reduced.

In the etching process, the operation modes are switched as described above as follows. That is, an etching end point detector 20 is attached to a chamber 11 for generating plasma, and the etching end point detector 2
By using a signal from 0, or by installing a control device capable of pre-programming the switching of the operation mode according to the passage of time, by using the signal of this control device, to determine the end of the main etching, Until the main etching is completed, etching is performed under the above main etching conditions,
After completion of the main etching, the etching is performed under the above-mentioned over-etching conditions.

In each of the above embodiments, the etching is performed on the polycrystalline silicon film. However, the present invention can be applied to etching of a metal such as an oxide film, a Si compound, aluminum or the like or a resist of a multilayer resist. Is obtained. When the present invention is applied to etching of aluminum, BCl ₃ + Cl ₂ or S
A chlorine-based gas such as iCl ₄ + Cl ₂ + CHCl ₃ is used, and the gas pressure is 0.1 Pa to 20 Pa.
It is preferable that According to an experiment, an etching rate of 400 to 900 nm / min was obtained in this case.

In the above-described embodiment, a parallel plate reactive ion etching apparatus is used as an apparatus for generating plasma. Instead, an electron cyclotron plasma generation apparatus or an electromagnetic induction type plasma generation apparatus may be used. In addition, a satisfactory effect can be obtained even in a plasma generator in which the power for generating plasma and the power for bias can be independently controlled.

Hereinafter, an electromagnetic induction type plasma etching apparatus according to another embodiment of the present invention and a dry etching method performed by using the apparatus will be described with reference to the drawings.

FIG. 37 shows a schematic configuration of an electromagnetic induction type plasma etching apparatus used in the plasma generating method according to the present invention. As shown in FIG. 37, a reactive gas is introduced into a metal chamber 11 via a gas controller 12, and the inside of the chamber 11 is controlled to an appropriate pressure by an exhaust system 13.

A spiral coil 25 is provided at the upper part of the chamber 11, and a sample stage 15 serving as a cathode (cathode) is provided at the lower part. The sample stage 15 has an impedance matching circuit 16 for forming a self-DC bias.
The first high-frequency power source 17 is connected via the. In order to generate plasma in the spiral coil 25,
A second high-frequency power source 28 is connected via an impedance matching circuit 27. The frequency of the first high-frequency power source 17 can be changed by the frequency control circuit 21, and the frequency of the second high-frequency power source 28 can be changed by the frequency control circuit 29.

The ion energy distribution and the width of the sheath region near the sample table 15 can be determined by the plasma parameter detector 26, and the etching end point can be determined by the etching end point detector 20 using a spectral method. Further, the gas controller 12 and the exhaust system 13 are controlled by a signal from the etching end point detector 20, and the gas pressure and the exhaust amount in the chamber 11 are appropriately controlled. Further, the frequency of the first high frequency power source 17 can be controlled via the frequency control circuit 21 by a signal from the etching end point detector 20.

The temperature of the sample stage 15 can be adjusted by controlling the heater 23 via the temperature control circuit 24. Further, the external parameter control device 22 controls the signal from the plasma parameter detector 26 and the signal from the etching end point detector 20, or the values of these signals and the external parameters such as frequency, gas pressure, high frequency power, and sample stage temperature. The gas controller 12, the exhaust system 13, the frequency control circuit 21, and the temperature control circuit 24 can be controlled on the basis of a combination of the above-described signals or a combination of these signals and a previously programmed processing flow.

Referring to FIG. 38, a specific embodiment of a dry etching method using the above-described electromagnetic induction type plasma etching apparatus will be described. That is, FIG. 38 (a) shows that Cl ₂ is introduced by only 40 sccm, and 300
Watts, bias power to 100 watts,
The gas pressure was set to a high vacuum of 3 Pa, and the exhaust amount was set to 100.
The result of etching at 0 liter / sec is shown. As shown in the figure, the deposition amount of the sidewall protective film is larger in the internal line pattern than in the isolated line pattern.
The pattern profile after the etching has a forward taper and the size is thick. FIG. 38B shows that the bias power is set to 150 while the gas pressure is kept constant at 3 Pa.
The results show that the wattage and the displacement were increased to 2000 liters / sec, the ion incidence distribution became more vertical, and the sidewall protection radicals reaching the pattern sidewalls decreased.
As shown in the figure, the amount of the protective film on the pattern side wall is reduced, the dimension reduction amount of the internal line pattern is larger than that of the isolated line pattern, the profiles of the isolated line pattern and the internal line pattern become more vertical, The dimensional difference between the line pattern and the internal line pattern has been reduced.

Further, the gas pressure may be reduced to 0.5 Pa, the high frequency power of the bias power may be increased from 13.56 MHz to 50 MHz, or the gas pressure may be reduced to 3 Pa.
To 1 Pa and the displacement is 200 liters /
A similar effect was observed when increasing to seconds.

[0206]

According to the first, second, third, and fourth dry etching methods, the line width of the first line pattern approaches the line width of the second line pattern,
And the line width of the second line pattern approaches the line width of the resist pattern, so that the line widths of the first and second line patterns are optimized.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a dry etching apparatus used in a dry etching method according to each embodiment of the present invention.

FIG. 2 is a schematic diagram showing a state in which ions starting from a boundary between a bulk plasma region and a sheath region are transported toward a sample stage while colliding with neutral particles in the sheath region.

FIG. 3 shows the characteristics of the incident distribution of ions starting from the boundary between the bulk plasma region and the sheath region when the gas pressure is 0.1 Pa, (a) showing the ion angle distribution,
(B) shows the ion energy distribution.

FIG. 4 shows the characteristics of the incident distribution of ions starting from the boundary between the bulk plasma region and the sheath region when the gas pressure is 0.2 Pa, (a) showing the ion angle distribution,
(B) shows the ion energy distribution.

FIG. 5 shows the characteristics of the incident distribution of ions starting from the boundary between the bulk plasma region and the sheath region when the gas pressure is 0.5 Pa, (a) showing the ion angle distribution,
(B) shows the ion energy distribution.

FIG. 6 shows the characteristics of the incident distribution of ions starting from the boundary between the bulk plasma region and the sheath region when the gas pressure is 1.0 Pa, (a) showing the ion angle distribution,
(B) shows the ion energy distribution.

FIG. 7 shows the characteristics of the incident distribution of ions starting from the boundary between the bulk plasma region and the sheath region when the gas pressure is 2.0 Pa, (a) showing the ion angle distribution,
(B) shows the ion energy distribution.

FIG. 8 shows the characteristics of the incident distribution of ions starting from the boundary between the bulk plasma region and the sheath region when the gas pressure is 3.0 Pa, (a) showing the ion angle distribution,
(B) shows the ion energy distribution.

9A and 9B show characteristics of an incident distribution of ions starting from a boundary between a bulk plasma region and a sheath region when a gas pressure is 5.0 Pa, and FIG. 9A shows an ion angle distribution;
(B) shows the ion energy distribution.

FIG. 10 shows the characteristics of the incident distribution of ions starting from the boundary between the bulk plasma region and the sheath region when the gas pressure is 10 Pa, (a) showing the ion angle distribution,
(B) shows the ion energy distribution.

FIG. 11 is a diagram showing the gas pressure dependence of the standard deviation σ representing the spread of the scattering angle in the incident angle distribution of ions starting from the boundary between the bulk plasma region and the sheath region, and the ion mean free path λ.

FIG. 12 shows a finite scattering angle ± in the angular distribution of ions starting from the boundary between the bulk plasma region and the sheath region.
It is a figure which shows the gas pressure dependence of the ratio with respect to the total number of incident ions of the ion which injects in (DELTA) degree.

FIG. 13 is a diagram showing the behavior of a sidewall protecting radical which is incident almost isotropically from above a line and space pattern.

FIG. 14 is a diagram showing a mechanism of a difference in profile and dimensional change between an internal line pattern and an isolated line pattern of a line-and-space pattern.

FIG. 15 is a diagram illustrating a state of a change in an internal parameter in a vacuum chamber when an external operation parameter including a gas pressure and a displacement is changed.

FIG. 16 is a diagram illustrating a state of a change in an internal parameter in a vacuum chamber when an external operation parameter including a bias power is changed.

FIG. 17 is a diagram illustrating a method for reducing a dimensional difference between an internal line pattern and an isolated line pattern in a case of a medium vacuum.

FIG. 18 is a diagram illustrating a method of reducing a dimensional difference between an internal line pattern and an isolated line pattern in a case of high vacuum.

FIG. 19 is a diagram for explaining means to be taken first to reduce a dimensional difference between an internal line pattern and an isolated line pattern in the case of medium vacuum and high vacuum.

20A to 20E show what measures to be taken thereafter to reduce the dimensional difference between the internal line pattern and the isolated line pattern in each of the cases (E) to (H) shown in FIG. FIG.

FIG. 21 is a sectional view showing a line pattern before dry etching.

FIG. 22 (a) shows the case where Cl ₂ is introduced at a flow rate of 40 sccm, the gas pressure is 10 Pa, medium vacuum,
When etching was performed at a rate of 1 liter / sec, the pattern profile after the etching showed a forward tapered state and a large size, and FIG.
FIG. 7B is a diagram showing a state in which the exhaust rate is increased to 2000 liter / second and the pattern profile is improved while maintaining the constant at a.

FIG. 23 (a) shows an etching process in which 40 sccm of Cl ₂ and 20 sccm of SiCl ₄ which is a side wall protecting radical are introduced, the gas pressure is 10 Pa and the vacuum is 1,500 liter / sec. In this case, the pattern profile after etching has a forward tapered shape and a large dimension, and FIG.
a, while keeping the exhaust rate constant at 1500 liters / sec, reduce the SiCl ₄ to 10 sccm
It is a figure showing the state where the profile was improved.

FIG. 24 (a) shows a pattern profile after etching when etching is performed under the conditions of a gas pressure of 8 Pa, a medium vacuum, and an exhaust amount of 1000 liter / second, with Cl ₂ introduced at 40 sccm. (B) is a diagram showing a state in which the pattern profile is improved by reducing the exhaust volume to 500 l / sec while maintaining the gas pressure constant at 8 Pa. .

FIG. 25 (a) shows Cl ₂ of 40 sccm, SiCl 4
Was introduced at a gas pressure of 10 Pa, medium vacuum, and an etching rate of 1000 liter / sec., The pattern profile after the etching became an inverse taper and the size was reduced. (B), 25 sc of SiCl ₄ while keeping the gas pressure constant at 10 Pa and the displacement at 1000 liter / sec.
It is a figure which shows the state which improved the pattern profile by increasing to cm.

FIG. 26 (a) shows a pattern profile after etching when etching is performed under the conditions of high vacuum of 4 Pa at a gas pressure of 4 Pa at a gas discharge of 1000 liter / second under the introduction of 40 sccm of Cl _2. FIG. 7B is a diagram showing a state in which the pattern profile is improved by increasing the evacuation volume to 2000 liter / second while maintaining the gas pressure constant at 4 Pa while forming a forward tapered and thick dimension.

FIG. 27 (a) shows Cl ₂ of 40 sccm, SiCl ₄
When the etching was performed under a high vacuum of 4 Pa at a gas pressure of 4 Pa, the pattern profile after the etching became a forward taper and the dimensions became thicker. ,
(B) is a diagram showing a state in which SiCl ₄ is reduced to 10 sccm and the pattern profile is improved while the gas pressure is kept constant at ₄ Pa and the displacement is kept constant at 1000 liter / second.

FIG. 28 (a) shows a pattern profile after etching when etching is performed under the conditions of high vacuum of 4 Pa at a gas pressure of 4 Pa and Cl ₂ introduced at a flow rate of 40 liters / sec. FIG. 4B shows a state in which the taper is reverse tapered and the dimensions are thin, and FIG. 4B shows a state in which the exhaust gas volume is reduced to 500 liter / sec and the pattern profile is improved while the gas pressure is kept constant at 4 Pa. .

FIG. 29 (a) shows Cl ₂ of 40 sccm, SiCl 4
Is introduced, the etching is performed at a gas pressure of 4 Pa under high vacuum conditions with an exhaust rate of 1000 liter / sec. Show,
(B) is a diagram showing a state in which the pattern profile is improved by increasing SiCl ₄ to 25 sccm while keeping the gas pressure constant at ₄ Pa and the displacement at 1000 liter / sec.

FIG. 30 (a) shows an introduction of Cl ₂ at a flow rate of 40 sccm, a gas pressure of 10 Pa and a medium vacuum, and
When etching was performed with a liter / second and a bias power of 300 watts, the pattern
The profile shows a forward tapered and thickened state, and (b) shows that the gas pressure is increased to 15 Pa and the bias power is increased to 400 watts while the displacement is kept constant at 1000 l / sec. It is a figure showing the state where pattern profile was improved.

FIG. 31 (a) shows an introduction of Cl ₂ at a flow rate of 40 sccm, a gas pressure of 10 Pa and a medium vacuum, and
When etching was performed with a liter / second and a bias power of 300 watts, the pattern
The profile shows a forward tapered and thickened state. (B) With the bias power kept constant at 300 watts, the gas pressure was increased to 15 Pa and the displacement was increased to 2000 l / sec. It is a figure showing the state where pattern profile was improved.

FIG. 32 (a) shows a case where etching is performed by introducing Cl ₂ at a flow rate of 40 sccm, a gas pressure of 4 Pa, a high vacuum, a pumping amount of 1000 liter / second, and a high frequency power frequency of 13.56 MHz. FIG. 3B shows a state in which the pattern profile after the etching has an inverse taper and the dimensions are small, and (b) shows a gas pressure of 4 Pa and a displacement of 10
FIG. 11 is a diagram showing a state in which the frequency of the high-frequency power is increased to 50 MHz and the pattern profile is improved while being kept constant at 00 liter / second.

FIG. 33 (a) shows a case where etching is performed by introducing 40 sccm of Cl _2, setting a gas pressure to 4 Pa, and performing a vacuum at a displacement of 800 liters / second and a high frequency power of 50 MHz. The pattern profile after etching has an inversely tapered and narrow dimension. (B) The pattern profile is obtained by increasing the frequency of the high-frequency power to 100 MHz while keeping the displacement at 800 l / sec. FIG. 6 is a diagram showing a state in which is improved.

FIG. 34 (a) shows a case where etching is performed by introducing 40 sccm of Cl ₂ , applying a gas pressure of 4 Pa, and a high vacuum at a gas exhaust rate of 1000 liter / second and a sample stage temperature of 30 ° C. (B) shows a state in which the pattern profile after etching has a forward taper and the dimensions are thick;
FIG. 4 is a diagram showing a state in which the sample profile temperature is increased to 80 ° C. and the pattern profile is improved while the gas pressure is kept constant at 4 Pa and the displacement is kept constant at 1000 liter / second.

FIG. 35 (a) shows the case where Cl ₂ is introduced at 40 sccm, the gas pressure is 10 Pa, medium vacuum, and the displacement is 1000.
Liter / sec, when the sample stage temperature was set to 30 degrees and the etching was performed, the pattern profile after the etching was reverse tapered and the size was small,
(B) is a diagram showing a state in which the pattern profile is improved by lowering the sample stage temperature to 0 ° while keeping the gas pressure constant at 10 Pa and the exhaust volume at 1000 liter / sec.

FIG. 36 shows a state in which, when forming a phosphorus-doped polycrystalline silicon gate using a parallel plate reactive ion dry etching apparatus, etching is performed by switching between a main etching operation mode and an over etching operation mode, 3) shows the state of etching under the main etching conditions, (b) shows the state of etching under over-etching conditions, and (c) shows the state of etching under improved over-etching conditions.

FIG. 37 is a schematic view of another dry etching apparatus used for the plasma generation method according to the present invention.

[Figure 38] A state in which the formation of the polysilicon gate that is phosphorus-doped using a dry etching apparatus shown in FIG. 37, (a) is a Cl ₂ introduced 40 sccm, to the plasma generation helical coil 300 watts, bias power 1000 watts, gas pressure 3 Pa
When etching was performed under high vacuum conditions with an exhaust volume of 100 liters / sec, the pattern
The profile shows a state in which the profile has a forward taper and the dimensions are wide.
FIG. 4 is a diagram showing a state in which the pattern profile is improved by increasing the volume to 1 liter / second.

[Explanation of symbols]

 Reference Signs List 11 metal chamber 12 gas controller 13 exhaust system 14 anode (anode) 15 sample stage (cathode) 16 impedance matching circuit 17 high-frequency power supply (first high-frequency power supply) 20 etching end point detector 21 frequency control circuit 22 external operation parameter control device Reference Signs List 23 heater 24 sample stage temperature controller 25 spiral coil 26 plasma parameter detector 27 impedance matching circuit 28 second high frequency power supply 29 frequency control circuit 30 photoresist pattern 31 phosphorus-doped polycrystalline silicon film 32 thermal oxide film 33 silicon substrate 34 Sidewall protective deposition film such as reaction product 35 Ions 36 Sidewall protective deposition film such as etched reaction product 40 Sidewall protective radical

Claims (24)

(57) [Claims] 1. A dry etching method for manufacturing a semiconductor integrated circuit, comprising: an etching step of performing dry etching on a film to be etched using plasma, wherein the etching step is performed before the etching film.
Into the vacuum chamber containing the etching film.
When the etching is performed under the first pressure condition of the incoming raw material gas, the pattern width of the first line pattern located inside the line pattern group including a plurality of line patterns formed close to each other and the line The pattern width of each of the outermost line patterns in the pattern group or the second line pattern formed separately from the line pattern group is larger than the mask width, and the pattern width of the first line pattern is larger than the mask width. Smaller than the pattern width of the second line pattern
In this case, the amount of the first sidewall protection film deposited on the pattern sidewall of the first line pattern by the sidewall protection gas is flat.
A pattern of the first line pattern by ions in the mask
More than the first etching amount where the sidewalls are etched.
And on the side wall of the pattern of the second line pattern
Amount of second sidewall protective film deposited by wall protective gas
Is the second line pattern due to ions in the plasma.
Etching in which the pattern sidewall of the pattern is etched
Larger than the amount of the first side wall protective film.
First sidewall protection obtained by subtracting the first etching amount from the first sidewall
Whether the effective amount of the film is the amount of the second side wall protective film
Second sidewall protection obtained by subtracting the second etching amount from the second sidewall
When the amount is smaller than the effective adhesion amount of the film, the adhesion amount of the first sidewall protection film and the first etching
And the amount of the second side wall protective film is substantially equal.
The adhering amount and the second etching amount are almost equal.
As described above, for the film to be etched,
Under the second pressure condition higher than the first pressure condition of the raw material gas
The first line pattern is etched by performing etching.
Pattern width is almost equal to the mask width and
The pattern width of the second line pattern is also substantially equal to the mask width.
A dry etching method characterized by including a step of making them equal . 2. A plasma processing method for manufacturing a semiconductor integrated circuit.
Performing dry etching to be etching grayed film with Ma
A dry etching method with an etching process
In the etching step, the film to be etched is
From the vacuum chamber where the etching film is stored
Etching according to the first emission condition of exhaust gas to be exhausted
Multiple lines formed close to each other
In the line pattern group consisting of
The pattern width of the first line pattern to be
Outermost line pattern in the pattern group
Or a line formed in isolation from the line pattern group
The pattern width of both line patterns is the mask width
And the pattern of the first line pattern
Pattern width is smaller than the pattern width of the second line pattern.
In this case, the sidewall protection pattern is provided on the pattern sidewall of the first line pattern.
The amount of the first sidewall protective film adhered by the
A pattern of the first line pattern by ions in the mask
More than the first etching amount where the sidewalls are etched.
And on the side wall of the pattern of the second line pattern
Amount of second sidewall protective film deposited by wall protective gas
Is the second line pattern due to ions in the plasma.
Etching in which the pattern sidewall of the pattern is etched
Larger than the amount of the first side wall protective film.
First sidewall protection obtained by subtracting the first etching amount from the first sidewall
Whether the effective amount of the film is the amount of the second side wall protective film
Second sidewall protection obtained by subtracting the second etching amount from the second sidewall
When the amount is smaller than the effective adhesion amount of the film, the adhesion amount of the first sidewall protection film and the first etching
And the amount of the second side wall protective film is substantially equal.
The adhering amount and the second etching amount are almost equal.
As described above, for the film to be etched,
A second emission condition that is greater than the first emission condition of the exhaust gas;
The first line by etching
If the pattern width of the pattern is almost equal to the mask width,
The pattern width of the second line pattern is also equal to the mask width.
A dry etching method characterized by including a step of making them substantially equal . 3. A plasma processing method for manufacturing a semiconductor integrated circuit.
Perform dry etching on the film to be etched using a mask
A dry etching method with an etching process
In the etching step, the film to be etched is
The first temperature of the sample stage on which the film to be etched is held
When etching is performed under different conditions,
Pattern consisting of multiple line patterns formed by
Of the first line pattern located inside the
Pattern width and outermost in the line pattern group
Line pattern or the line pattern group
Of the second line pattern formed in isolation from the
Each of the widths is larger than the mask width, and the first
The pattern width of the line pattern is the second line pattern.
The width is smaller than the pattern width of the first line pattern.
The amount of the first sidewall protective film adhered by the
A pattern of the first line pattern by ions in the mask
More than the first etching amount where the sidewalls are etched.
And on the side wall of the pattern of the second line pattern
Amount of second sidewall protective film deposited by wall protective gas
Is the second line pattern due to ions in the plasma.
Etching in which the pattern sidewall of the pattern is etched
Larger than the amount of the first side wall protective film.
First sidewall protection obtained by subtracting the first etching amount from the first sidewall
Whether the effective amount of the film is the amount of the second side wall protective film
Second sidewall protection obtained by subtracting the second etching amount from the second sidewall
When the amount is smaller than the effective adhesion amount of the film, the adhesion amount of the first sidewall protection film and the first etching
And the amount of the second side wall protective film is substantially equal.
The adhering amount and the second etching amount are almost equal.
As described above, for the film to be etched,
At a second temperature condition higher than the first temperature condition of the sample stage,
The first line pattern by performing
Pattern width is substantially equal to the mask width, and
The pattern width of the second line pattern is also approximately equal to the mask width
A dry etching method comprising a step of making the etching easier. 4. A dry etching method for manufacturing a semiconductor integrated circuit, comprising an etching step of performing dry etching on a film to be etched using plasma, wherein the etching step is performed before the etching film.
Into the vacuum chamber containing the etching film.
When the etching is performed under the first pressure condition of the incoming raw material gas, the pattern width of the first line pattern located inside the line pattern group including a plurality of line patterns formed close to each other and the line The pattern width of each of the outermost line patterns in the pattern group or the second line pattern formed separately from the line pattern group is larger than the mask width, and the pattern width of the first line pattern is larger than the mask width. Greater than the pattern width of the second line pattern
In this case, the amount of the first sidewall protection film deposited on the pattern sidewall of the first line pattern by the sidewall protection gas is flat.
A pattern of the first line pattern by ions in the mask
More than the first etching amount where the sidewalls are etched.
And on the side wall of the pattern of the second line pattern
Amount of second sidewall protective film deposited by wall protective gas
Is the second line pattern due to ions in the plasma.
Etching in which the pattern sidewall of the pattern is etched
Larger than the amount of the first side wall protective film.
First sidewall protection obtained by subtracting the first etching amount from the first sidewall
Whether the effective amount of the film is the amount of the second side wall protective film
Second sidewall protection obtained by subtracting the second etching amount from the second sidewall
In the case where the amount is larger than the effective adhesion amount of the film, the adhesion amount of the first side wall protective film and the first etching
And the amount of the second side wall protective film is substantially equal.
The adhering amount and the second etching amount are almost equal.
As described above, for the film to be etched,
Under a second pressure condition lower than the first pressure condition of the raw material gas
The first line pattern is etched by performing etching.
Pattern width is almost equal to the mask width and
The pattern width of the second line pattern is also substantially equal to the mask width.
A dry etching method characterized by including a step of making them equal . 5. A plasma processing method for manufacturing a semiconductor integrated circuit.
Perform dry etching on the film to be etched using a mask
A dry etching method with an etching process
In the etching step, the film to be etched is
From the vacuum chamber where the etching film is stored
Etching according to the first emission condition of exhaust gas to be exhausted
Multiple lines formed close to each other
In the line pattern group consisting of
The pattern width of the first line pattern to be
Outermost line pattern in the pattern group
Or a line formed in isolation from the line pattern group
The pattern width of both line patterns is the mask width
And the pattern of the first line pattern
Pattern width is larger than the pattern width of the second line pattern.
In this case, a sidewall protection gas is provided on the pattern sidewall of the first line pattern.
The amount of the first sidewall protective film adhered by the
A pattern of the first line pattern by ions in the mask
More than the first etching amount where the sidewalls are etched.
And on the side wall of the pattern of the second line pattern
Amount of second sidewall protective film deposited by wall protective gas
Is the second line pattern due to ions in the plasma.
Etching in which the pattern sidewall of the pattern is etched
Larger than the amount of the first side wall protective film.
First sidewall protection obtained by subtracting the first etching amount from the first sidewall
Whether the effective amount of the film is the amount of the second side wall protective film
Second sidewall protection obtained by subtracting the second etching amount from the second sidewall
In the case where the amount is larger than the effective adhesion amount of the film, the adhesion amount of the first side wall protective film and the first etching
And the amount of the second side wall protective film is substantially equal.
The adhering amount and the second etching amount are almost equal.
As described above, for the film to be etched,
A second emission condition that is greater than the first emission condition of the exhaust gas;
The first line by etching
If the pattern width of the pattern is almost equal to the mask width,
The pattern width of the second line pattern is also equal to the mask width.
A dry etching method characterized by including a step of making them substantially equal . 6. A plasma processing apparatus for manufacturing a semiconductor integrated circuit.
Perform dry etching on the film to be etched using a mask
A dry etching method with an etching process
In the etching step, the film to be etched is
The first temperature of the sample stage on which the film to be etched is held
When etching is performed under different conditions,
Pattern consisting of multiple line patterns formed by
Of the first line pattern located inside the
Pattern width and outermost in the line pattern group
Line pattern or the line pattern group
Of the second line pattern formed in isolation from the
Width with not larger than either the mask width, the first
The pattern width of the line pattern is the second line pattern.
The width of the first line pattern is larger than the pattern width of the first line pattern.
The amount of the first sidewall protective film adhered by the
A pattern of the first line pattern by ions in the mask
More than the first etching amount where the sidewalls are etched.
And on the side wall of the pattern of the second line pattern
Amount of second sidewall protective film deposited by wall protective gas
Is the second line pattern due to ions in the plasma.
Etching in which the pattern sidewall of the pattern is etched
Larger than the amount of the first side wall protective film.
First sidewall protection obtained by subtracting the first etching amount from the first sidewall
Whether the effective amount of the film is the amount of the second side wall protective film
Second sidewall protection obtained by subtracting the second etching amount from the second sidewall
In the case where the amount is larger than the effective adhesion amount of the film, the adhesion amount of the first side wall protective film and the first etching
And the amount of the second side wall protective film is substantially equal.
The adhering amount and the second etching amount are almost equal.
As described above, for the film to be etched,
At a second temperature condition higher than the first temperature condition of the sample stage,
The first line pattern by performing
Pattern width is substantially equal to the mask width, and
The pattern width of the second line pattern is also approximately equal to the mask width
A dry etching method comprising a step of making the etching easier. 7. A dry etching method for manufacturing a semiconductor integrated circuit, comprising: an etching step of performing dry etching on a film to be etched using plasma, wherein the etching step is performed before the etching film.
Into the vacuum chamber containing the etching film.
When the etching is performed under the first pressure condition of the incoming raw material gas, the pattern width of the first line pattern located inside the line pattern group including a plurality of line patterns formed close to each other and the line The pattern width of each of the outermost line patterns in the pattern group or the second line pattern formed separately from the line pattern group is smaller than the mask width, and the pattern width of the first line pattern is smaller than the mask width. Greater than the pattern width of the second line pattern
In this case, the amount of the first sidewall protection film deposited on the pattern sidewall of the first line pattern by the sidewall protection gas is flat.
A pattern of the first line pattern by ions in the mask
Less than the first etching amount in which the sidewalls are etched.
And on the pattern side wall of the second line pattern
Amount of second sidewall protective film deposited by sidewall protective gas
Is the second line pattern due to ions in the plasma.
Etching in which the pattern sidewall of the pattern is etched
If the amount is larger than the amount, the amount of the first sidewall protective film deposited and the first etching
And the amount of the second side wall protective film is substantially equal.
The adhering amount and the second etching amount are almost equal.
As described above, for the film to be etched,
Under a second pressure condition lower than the first pressure condition of the raw material gas
The first line pattern is etched by performing etching.
Pattern width is almost equal to the mask width and
The pattern width of the second line pattern is also substantially equal to the mask width.
A dry etching method characterized by including a step of making them equal . 8. A plasma processing method for manufacturing a semiconductor integrated circuit.
Perform dry etching on the film to be etched using a mask
A dry etching method with an etching process
In the etching step, the film to be etched is
From the vacuum chamber where the etching film is stored
Etching according to the first emission condition of exhaust gas to be exhausted
Multiple lines formed close to each other
In the line pattern group consisting of
The pattern width of the first line pattern to be
Outermost line pattern in the pattern group
Or a line formed in isolation from the line pattern group
The pattern width of both line patterns is the mask width
And the pattern of the first line pattern
Pattern width is larger than the pattern width of the second line pattern.
In this case, a sidewall protection gas is provided on the pattern sidewall of the first line pattern.
The amount of the first sidewall protective film adhered by the
A pattern of the first line pattern by ions in the mask
Less than the first etching amount in which the sidewalls are etched.
And on the pattern side wall of the second line pattern
Amount of second sidewall protective film deposited by sidewall protective gas
Is the second line pattern due to ions in the plasma.
Second etching patterns sidewalls of emissions is etched
If the amount is larger than the amount, the amount of the first sidewall protective film deposited and the first etching
And the amount of the second side wall protective film is substantially equal.
The adhering amount and the second etching amount are almost equal.
As described above, for the film to be etched,
A second emission condition that is greater than the first emission condition of the exhaust gas;
The first line by etching
If the pattern width of the pattern is almost equal to the mask width,
The pattern width of the second line pattern is also equal to the mask width.
A dry etching method characterized by including a step of making them substantially equal . 9. A plasma processing method for manufacturing a semiconductor integrated circuit.
Perform dry etching on the film to be etched using a mask
A dry etching method with an etching process
In the etching step, the film to be etched is
The first temperature of the sample stage on which the film to be etched is held
When etching is performed under different conditions,
Pattern consisting of multiple line patterns formed by
Of the first line pattern located inside the
Pattern width and outermost in the line pattern group
Line pattern or the line pattern group
Of the second line pattern formed in isolation from the
Each of the widths is smaller than the mask width, and the first
The pattern width of the line pattern is the second line pattern.
The width of the first line pattern is larger than the pattern width of the first line pattern.
The amount of the first sidewall protective film adhered by the
A pattern of the first line pattern by ions in the mask
Less than the first etching amount in which the sidewalls are etched.
And on the pattern side wall of the second line pattern
Amount of second sidewall protective film deposited by sidewall protective gas
Is the second line pattern due to ions in the plasma.
Etching in which the pattern sidewall of the pattern is etched
If the amount is larger than the amount, the amount of the first sidewall protective film deposited and the first etching
And the amount of the second side wall protective film is substantially equal.
The adhering amount and the second etching amount are almost equal.
As described above, for the film to be etched,
At a second temperature condition higher than the first temperature condition of the sample stage,
The first line pattern
Pattern width is substantially equal to the mask width, and
The pattern width of the second line pattern is also approximately equal to the mask width
A dry etching method comprising a step of making the etching easier. 10. A dry etching method for manufacturing a semiconductor integrated circuit, comprising: an etching step of performing dry etching on a film to be etched using plasma, wherein the etching step is performed before the etching film.
Into the vacuum chamber containing the etching film.
When the etching is performed under the first pressure condition of the incoming raw material gas, the pattern width of the first line pattern located inside the line pattern group including a plurality of line patterns formed close to each other and the line The pattern width of each of the outermost line patterns in the pattern group or the second line pattern formed separately from the line pattern group is larger than the mask width, and the pattern width of the first line pattern is larger than the mask width. Smaller than the pattern width of the second line pattern
In this case, the amount of the first sidewall protection film deposited on the pattern sidewall of the first line pattern by the sidewall protection gas is flat.
A pattern of the first line pattern by ions in the mask
More than the first etching amount where the sidewalls are etched.
And on the side wall of the pattern of the second line pattern
Amount of second sidewall protective film deposited by wall protective gas
Is the second line pattern due to ions in the plasma.
Etching in which the pattern sidewall of the pattern is etched
If the amount is smaller than the amount, the amount of adhesion of the first sidewall protective film and the first etching
And the amount of the second side wall protective film is substantially equal.
The adhering amount and the second etching amount are almost equal.
As described above, for the film to be etched,
Under a second pressure condition lower than the first pressure condition of the raw material gas
The first line pattern is etched by performing etching.
Pattern width is almost equal to the mask width and
The pattern width of the second line pattern is also substantially equal to the mask width.
A dry etching method characterized by including a step of making them equal . 11. A method for manufacturing a semiconductor integrated circuit, comprising :
Perform dry etching on the film to be etched using
A dry etching how having the cormorants etching process
In the etching step, the film to be etched is
From the vacuum chamber where the etching film is stored
Etching according to the first emission condition of exhaust gas to be exhausted
Multiple lines formed close to each other
In the line pattern group consisting of
The pattern width of the first line pattern to be
Outermost line pattern in the pattern group
Or a line formed in isolation from the line pattern group
The pattern width of both line patterns is the mask width
And the pattern of the first line pattern
Pattern width is smaller than the pattern width of the second line pattern.
In this case, the sidewall protection pattern is provided on the pattern sidewall of the first line pattern.
The amount of the first sidewall protective film adhered by the
A pattern of the first line pattern by ions in the mask
More than the first etching amount where the sidewalls are etched.
And on the side wall of the pattern of the second line pattern
Amount of second sidewall protective film deposited by wall protective gas
Is the second line pattern due to ions in the plasma.
Etching in which the pattern sidewall of the pattern is etched
If the amount is smaller than the amount, the amount of adhesion of the first sidewall protective film and the first etching
And the amount of the second side wall protective film is substantially equal.
The adhering amount and the second etching amount are almost equal.
As described above, for the film to be etched,
A second emission that is less than the first emission condition of the exhaust gas
By performing etching under the conditions, the first line
Pattern width is almost equal to the mask width,
The pattern width of the second line pattern is also the mask width.
Characterized by including a step of substantially equal to
Dry etching method that. 12. A method for manufacturing a semiconductor integrated circuit, comprising :
Perform dry etching on the film to be etched using
Dry etching method with an etching process
In the etching step, the film to be etched is
The first temperature of the sample stage on which the film to be etched is held
When etching is performed under different conditions,
Pattern consisting of multiple line patterns formed by
Of the first line pattern located inside the
The outermost of definitive pattern width and the line pattern group
Line pattern or the line pattern group
Of the second line pattern formed in isolation from the
Each of the widths is larger than the mask width, and the first
The pattern width of the line pattern is the second line pattern.
The width is smaller than the pattern width of the first line pattern.
The amount of the first sidewall protective film adhered by the
A pattern of the first line pattern by ions in the mask
More than the first etching amount where the sidewalls are etched.
And on the side wall of the pattern of the second line pattern
Amount of second sidewall protective film deposited by wall protective gas
Is the second line pattern due to ions in the plasma.
Etching in which the pattern sidewall of the pattern is etched
If the amount is smaller than the amount, the amount of adhesion of the first sidewall protective film and the first etching
And the amount of the second side wall protective film is substantially equal.
The adhering amount and the second etching amount are almost equal.
As described above, for the film to be etched,
In a second temperature condition lower than the first temperature condition of the sample stage,
The first line pattern by performing
Pattern width is substantially equal to the mask width, and
The pattern width of the second line pattern is also approximately equal to the mask width
A dry etching method comprising a step of making the etching easier. 13. A dry etching method for manufacturing a semiconductor integrated circuit, comprising an etching step of performing dry etching on a film to be etched by using plasma, wherein the etching step is performed before the etching film.
Into the vacuum chamber containing the etching film.
When the etching is performed under the first pressure condition of the incoming raw material gas, the pattern width of the first line pattern located inside the line pattern group including a plurality of line patterns formed close to each other and the line The pattern width of each of the outermost line patterns in the pattern group or the second line pattern formed separately from the line pattern group is smaller than the mask width, and the pattern width of the first line pattern is smaller than the mask width. Greater than the pattern width of the second line pattern
In this case, the amount of the first sidewall protection film deposited on the pattern sidewall of the first line pattern by the sidewall protection gas is flat.
A pattern of the first line pattern by ions in the mask
Less than the first etching amount in which the sidewalls are etched.
And on the pattern side wall of the second line pattern
Amount of second sidewall protective film deposited by sidewall protective gas
Is the second line pattern due to ions in the plasma.
Etching in which the pattern sidewall of the pattern is etched
Less than the amount of the first sidewall protection film.
The first side wall thickness obtained by subtracting the first etching amount from
The effective amount of the protective film is the amount of the second sidewall protective film.
The second side wall thickness obtained by subtracting the second etching amount from the second side wall.
If the amount of the first protective film is larger than the effective amount of the protective film, the amount of the first side wall protective film and the first etching
And the amount of the second side wall protective film is substantially equal.
The adhering amount and the second etching amount are almost equal.
As described above, for the film to be etched,
Under a second pressure condition lower than the first pressure condition of the raw material gas
The first line pattern is etched by performing etching.
Pattern width is almost equal to the mask width and
The pattern width of the second line pattern is also substantially equal to the mask width.
A dry etching method characterized by including a step of making them equal . 14. A method for manufacturing a semiconductor integrated circuit, comprising :
Perform dry etching on the film to be etched using
Dry etching method with an etching process
In the etching step, the film to be etched is
From the vacuum chamber where the etching film is stored
Etching according to the first emission condition of exhaust gas to be exhausted
Multiple lines formed close to each other
In the line pattern group consisting of
The pattern width of the first line pattern to be
Outermost line pattern in the pattern group
Or a line formed in isolation from the line pattern group
The pattern width of both line patterns is the mask width
And the pattern of the first line pattern
Pattern width is larger than the pattern width of the second line pattern.
In this case, a sidewall protection gas is provided on the pattern sidewall of the first line pattern.
The amount of the first sidewall protective film adhered by the
A pattern of the first line pattern by ions in the mask
Less than the first etching amount in which the sidewalls are etched.
And on the pattern side wall of the second line pattern
Amount of second sidewall protective film deposited by sidewall protective gas
Is the second line pattern due to ions in the plasma.
Etching in which the pattern sidewall of the pattern is etched
Less than the amount of the first sidewall protection film.
The first side wall thickness obtained by subtracting the first etching amount from
The effective amount of the protective film is the amount of the second sidewall protective film.
The second side wall thickness obtained by subtracting the second etching amount from the second side wall.
If the amount of the first protective film is larger than the effective amount of the protective film, the amount of the first side wall protective film and the first etching
And the amount of the second side wall protective film is substantially equal.
The adhering amount and the second etching amount are almost equal.
As described above, for the film to be etched,
A second emission that is less than the first emission condition of the exhaust gas
By performing etching under the conditions, the first line
Pattern width is almost equal to the mask width,
The pattern width of the second line pattern is also the mask width.
Characterized by including a step of substantially equal to
Dry etching method that. 15. A method for manufacturing a semiconductor integrated circuit, comprising :
Perform dry etching on the film to be etched using
Dry etching method with an etching process
In the etching step, the film to be etched is
The first temperature of the sample stage on which the film to be etched is held
When etching is performed under different conditions,
Pattern consisting of multiple line patterns formed by
Of the first line pattern located inside the
Pattern width and outermost in the line pattern group
Line pattern or the line pattern group
Of the second line pattern formed in isolation from the
Each of the widths is smaller than the mask width, and the first
The pattern width of the line pattern is the second line pattern.
The width of the first line pattern is larger than the pattern width of the first line pattern.
The amount of the first sidewall protective film adhered by the
A pattern of the first line pattern by ions in the mask
Less than the first etching amount in which the sidewalls are etched.
And on the pattern side wall of the second line pattern
Amount of second sidewall protective film deposited by sidewall protective gas
Is the second line pattern due to ions in the plasma.
Second etching patterns sidewalls of emissions is etched
Less than the amount of the first sidewall protection film.
The first side wall thickness obtained by subtracting the first etching amount from
The effective amount of the protective film is the amount of the second sidewall protective film.
The second side wall thickness obtained by subtracting the second etching amount from the second side wall.
If the amount of the first protective film is larger than the effective amount of the protective film, the amount of the first side wall protective film and the first etching
And the amount of the second side wall protective film is substantially equal.
The adhering amount and the second etching amount are almost equal.
As described above, for the film to be etched,
In a second temperature condition lower than the first temperature condition of the sample stage,
The first line pattern by performing
Pattern width is substantially equal to the mask width, and
The pattern width of the second line pattern is also approximately equal to the mask width
A dry etching method comprising a step of making the etching easier. 16. A dry etching method for manufacturing a semiconductor integrated circuit, comprising an etching step of performing dry etching on a film to be etched using plasma, wherein the etching step is performed before the etching film.
Into the vacuum chamber containing the etching film.
When the etching is performed under the first pressure condition of the incoming raw material gas, the pattern width of the first line pattern located inside the line pattern group including a plurality of line patterns formed close to each other and the line The pattern width of each of the outermost line patterns in the pattern group or the second line pattern formed separately from the line pattern group is smaller than the mask width, and the pattern width of the first line pattern is smaller than the mask width. Smaller than the pattern width of the second line pattern
In this case, the amount of the first sidewall protection film deposited on the pattern sidewall of the first line pattern by the sidewall protection gas is flat.
A pattern of the first line pattern by ions in the mask
Less than the first etching amount in which the sidewalls are etched.
And on the pattern side wall of the second line pattern
Amount of second sidewall protective film deposited by sidewall protective gas
Is the second line pattern due to ions in the plasma.
Etching in which the pattern sidewall of the pattern is etched
Less than the amount of the first sidewall protection film.
The first side wall thickness obtained by subtracting the first etching amount from
Effective adhesion amount of protection film, the adhesion amount of the second sidewall protective film
The second side wall thickness obtained by subtracting the second etching amount from the second side wall.
If the amount is smaller than the effective amount of the protective film, the amount of the first side wall protective film and the first etching
And the amount of the second side wall protective film is substantially equal.
The adhering amount and the second etching amount are almost equal.
As described above, for the film to be etched,
Under a second pressure condition lower than the first pressure condition of the raw material gas
The first line pattern is etched by performing etching.
Pattern width is almost equal to the mask width and
The pattern width of the second line pattern is also substantially equal to the mask width.
A dry etching method characterized by including a step of making them equal . 17. A method for manufacturing a semiconductor integrated circuit, comprising :
Perform dry etching on the film to be etched using
Dry etching method with an etching process
In the etching step, the film to be etched is
From the vacuum chamber where the etching film is stored
Etching according to the first emission condition of exhaust gas to be exhausted
Multiple lines formed close to each other
In the line pattern group consisting of
The pattern width of the first line pattern to be
Outermost line pattern in the pattern group
Or a line formed in isolation from the line pattern group
The pattern width of both line patterns is the mask width
And the pattern of the first line pattern
Pattern width is smaller than the pattern width of the second line pattern.
In this case, the sidewall protection pattern is provided on the pattern sidewall of the first line pattern.
The amount of the first sidewall protective film adhered by the
A pattern of the first line pattern by ions in the mask
Less than the first etching amount in which the sidewalls are etched.
And on the pattern side wall of the second line pattern
Amount of second sidewall protective film deposited by sidewall protective gas
Is the second line pattern due to ions in the plasma.
Etching in which the pattern sidewall of the pattern is etched
Less than the amount of the first sidewall protection film.
The first side wall thickness obtained by subtracting the first etching amount from
The effective amount of the protective film is the amount of the second sidewall protective film.
The second side wall thickness obtained by subtracting the second etching amount from the second side wall.
If the amount is smaller than the effective amount of the protective film, the amount of the first side wall protective film and the first etching
And the amount of the second side wall protective film is substantially equal.
The adhering amount and the second etching amount are almost equal.
As described above, for the film to be etched,
A second emission that is less than the first emission condition of the exhaust gas
By performing etching under the conditions, the first line
Pattern width is almost equal to the mask width,
The pattern width of the second line pattern is also the mask width.
Characterized by including a step of substantially equal to
Dry etching method that. 18. A method for manufacturing a semiconductor integrated circuit, comprising :
Perform dry etching on the film to be etched using
Dry etching method with an etching process
In the etching step, the film to be etched is
The first temperature of the sample stage on which the film to be etched is held
When etching is performed under different conditions,
Pattern consisting of multiple line patterns formed by
Of the first line pattern located inside the
Pattern width and outermost in the line pattern group
Line pattern or the line pattern group
Of the second line pattern formed in isolation from the
Each of the widths is smaller than the mask width, and the first
The pattern width of the line pattern is the second line pattern.
The width is smaller than the pattern width of the first line pattern.
The amount of the first sidewall protective film adhered by the
A pattern of the first line pattern by ions in the mask
Less than the first etching amount in which the sidewalls are etched.
And on the pattern side wall of the second line pattern
Amount of second sidewall protective film deposited by sidewall protective gas
Is the second line pattern due to ions in the plasma.
Etching in which the pattern sidewall of the pattern is etched
Less than the amount of the first sidewall protection film.
The first side wall thickness obtained by subtracting the first etching amount from
The effective amount of the protective film is the amount of the second sidewall protective film.
The second side wall thickness obtained by subtracting the second etching amount from the second side wall.
If the amount is smaller than the effective amount of the protective film, the amount of the first side wall protective film and the first etching
And the amount of the second side wall protective film is substantially equal.
Approximately equal Kunar deposition amount and the second amount of etching is
As described above, for the film to be etched,
At a second temperature condition higher than the first temperature condition of the sample stage,
The first line pattern by performing
Pattern width is substantially equal to the mask width, and
The pattern width of the second line pattern is also approximately equal to the mask width
A dry etching method comprising a step of making the etching easier. 19. The method according to claim 19, wherein the etching step comprises :
The probability that ions in plasma transported toward the sample stage in a sheath region formed in the vicinity of the sample stage in which the sealing film is held are scattered by collision with neutral particles in the sheath region, Almost proportional to the square root of gas pressure
Using the relationship of that, a second pressure condition of the raw material gas
By setting the first side wall protective film and the second side wall protective film,
Claims sidewall protective film is characterized in that it comprises a step of controlling the amount to be etched by the ions in the plasma
The dry etching method according to 1, 4, 7, 10, 13 or 16 . 20. The etching step, wherein the etching is
The width of the sheath region formed in the vicinity of the sample stage where the film is held is 1/3 to 1/2 of the pressure of the source gas.
The second pressure condition of the source gas is obtained by using a relationship that the ratio is inversely proportional to the power and a relationship that the incident energy of ions in the plasma on the sample stage decreases as the width of the sheath region increases. By setting
17. The dry etching according to claim 1 , further comprising the step of controlling the amount of etching of the side wall protective film and the second side wall protective film by ions in the plasma. Method. 21. The etching step, comprising:
At higher temperatures, using the relationship that the adsorption rate of the side wall protective radicals for forming the first sidewall protective film and the second sidewall protective film is reduced, the sample stage of the second temperature condition
19. The method according to claim 3 , further comprising the step of controlling the amount of adhesion of the first side wall protective film and the second side wall protective film by setting. Etching method. 22. The film to be etched wherein phosphorus is doped.
The source gas is chlorine.
Gas, and the second pressure condition of the source gas is 4 to 10
Exhaust gas discharged from the vacuum chamber
Discharge rate is over 2000 liters / sec.
The dry etching method according to claim 1, 4, 7, 10, 13 , or 16 . 23. The film to be etched wherein phosphorus is doped.
The source gas is chlorine.
It includes a gas, in the vacuum chamber from SiCl ₄
10-25 sccm are introduced,
The second pressure condition of the source gas is 0.5 to 10 Pa.
Of the exhaust gas discharged from the vacuum chamber
Is characterized in that it is 800-2000 liters / sec.
17. The dry etching method according to claim 1, 4, 7, 10, 13 , or 16 . 24. The film to be etched is doped with phosphorus.
The source gas is chlorine.
Gas, and the second temperature condition of the sample stage is the second temperature condition.
Change between 0 and 80 ° C according to the amount of the sidewall protective film deposited
Claims 3, 6, 9, 12, 15 or
19. The dry etching method according to 18 .