JP3288306B2 - Method for manufacturing semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method of manufacturing a semiconductor equipment using plasma.

[0002]

2. Description of the Related Art In the current production of semiconductor devices,
Plasma processing in which plasma is generated in a reaction chamber to perform dry etching or CVD is an indispensable technique for processing elements in a highly integrated semiconductor device. For example, when forming a contact hole for connecting a wiring to an active region such as a source / drain region of a transistor or a via hole for connecting a wiring in an interlayer insulating film made of an oxide film, a reaction is required. Plasma is generated in the chamber, and the progress of the etching in the side surface direction of the hole is suppressed by the side wall protective film, and the etching is advanced by the collision of plasma ions on the bottom surface of the hole. By such anisotropic etching,
It is possible to form a contact hole or a via hole that penetrates the interlayer insulating film almost straight while having a fine diameter.

[0003] With the reduction in the size of semiconductor devices, the width of wiring and the diameter of contact holes and via holes are becoming smaller. However, taking the hole forming process as an example, the thickness of the interlayer insulating film is hardly reduced regardless of the hole diameter being reduced. Therefore, the ratio of the thickness of the interlayer insulating film to the hole diameter (aspect ratio) is increasing. Then, as the aspect ratio increases, a case where a normal hole is not formed tends to occur in a step of forming a hole. In particular, when a hole having a high aspect ratio is formed, a phenomenon called a microloading phenomenon in which the etch rate changes depending on the hole diameter is likely to occur. In particular, when this microloading effect occurs when a hole having a small diameter is formed, the progress of etching gradually slows down, and sometimes etching may stop before a through hole is formed.

On the other hand, with the recent progress of the dry etching technique, a technique called TM etching (Time Modeling Etching) in which formation and etching of the sidewall protective film are alternately performed in order to minimize the generation of the sidewall protective film,
There is a technique called a low-temperature etching technique that lowers the wafer temperature until the radical reaction on the side wall freezes, and realizes anisotropic etching without forming a side wall protective film. According to these techniques, it is possible to secure anisotropy while eliminating or reducing the side wall protective film. The occurrence of the above-described microloading phenomenon is also suppressed.

Recently, as a plasma source suitable for etching a hole having a high aspect ratio, an inductively coupled plasma or a helicon wave plasma having a low gas pressure and a high density in which an antenna is installed on a wall of an insulating reaction chamber is used. By using this, high anisotropy, high etch rate and high selectivity can be realized without forming a side wall protective film.

[0006]

However, in this technique using high-density plasma, there is a phenomenon that the progress of etching is stopped halfway and no through-hole is formed. Such an etch stop is a phenomenon in which etching is suddenly stopped halfway in a state where a through-hole has been formed normally. In addition, the timing of the occurrence of the etch stop may vary immediately after the start of the etching, or may occur after the progress of the etching, and does not show a certain tendency. While several wafers are being processed, an etch stop occurs suddenly while a certain wafer is being etched, which implies that some factors accumulate and occur.

Although the cause of such variation has not yet been elucidated in detail, it is a phenomenon that can be clearly distinguished from the microloading described above. Therefore, the present inventors refer to such a phenomenon that the etching stops as "etch stop".

FIG. 37 is a diagram showing the progress of etching in the three cases of normal etching, microloading and the etch stop in question here. In the figure, the horizontal axis represents the etching time, and the vertical axis represents the etching amount. And the etching line E
tn indicates the case of normal etching, etching line Eml indicates the case where microloading occurs, and etching line Est
Indicates a case where an etch stop occurs. In the case of microloading, the etching line Eml in FIG.
As shown in (1), when a certain depth is reached, the etching progresses slowly. On the other hand, in the case of the etch stop, as shown by the etching line Est in FIG. 37, the progress of the etching is suddenly stopped from the normal state of the progress of the etching, and as described above, the occurrence time varies. That is, while the microloading effect is a phenomenon caused by a continuous decrease in the etching rate, the “etch stop” here is
This can be said to be a phenomenon caused by the etching rate being discontinuously reduced to 0 from a state where normal etching is being performed at a certain etching rate. Moreover, even under the condition where the microloading effect does not occur, the etch stop occurs.

Here, generally, an etching rate R in plasma etching is represented by the following equation (1).

R = (1 / ρ) · θ · Γi · Ei−θ · Γd (1) where ρ is the density of the object to be etched, θ is the surface coverage of radicals, and Δi is the amount of ion flux. Function, E
i represents ion energy, and Δd represents a function representing the amount of radical flux. The first term of the equation (1) is a factor contributing to etching, and the second term is a factor contributing to deposition.

Stopping the etching means that the etching rate R in the above equation (1) becomes 0 or less. And in order to satisfy such R ≦ 0,
The following conditions are required. (A) In the case of ≒ i ≒ 0 In this case, the amount of ion flux entering the contact hole decreases. This state occurs due to an increase in the aspect ratio of the contact hole, surface charging, and the like. (B) In the case of Ei こ の 0 In this case, the energy of ions entering the contact hole decreases. This state is caused particularly by the presence of a charge that inhibits the downward movement of ions in the contact hole formed in the insulating film. For example, there is a case where the bottom surface of the contact hole has a positive charge and the top portion of the contact hole has a negative charge on the side wall. (C) (1 / ρ) · θ ·） i · Ei ≦ θ · Γd This is a case where the amount of radicals contributing to deposition exceeds the amount of ions contributing to etching. This is caused by an increase in the C ₂ / F ratio or the C / F ratio in the plasma.

In general, the microloading effect can be said to be a phenomenon caused by the above condition (c). Although the mechanism of these phenomena has not yet been elucidated, the microloading effect is a phenomenon in which the amount of depot radicals supplied into the holes increases continuously and the etching rate gradually decreases, and the function Γi,
While Γd is represented as a continuous function, it is estimated that the etch stop is a phenomenon in which the etching rate suddenly becomes 0, and the functions Γi and Γd are represented as discontinuous functions.

The present invention has been made as a result of accumulating many experiments for investigating the cause of the etch stop phenomenon. The present invention is based on the understanding of the conditions under which an etch stop occurs and the conditions under which an etch stop does not occur. , and to provide a manufacturing method of a semiconductor device which can reliably eliminate the etch stop.

[0014]

Means taken by the present invention to achieve the above object are to release oxygen from the wall surface of the reaction chamber or supply a gas containing oxygen to advance the plasma processing such as etching. The elimination of obstructive deposits.

The method of manufacturing a semi-conductor device of the present invention, apparatus including a reaction chamber having an oxygen-containing member made of a material containing oxygen in the wall, and an antenna coil provided in proximity to the oxygen-containing member A method of manufacturing a semiconductor device using the method, when replacing the oxygen-containing member, measuring the amount of oxygen released from the oxygen-containing member, the amount of oxygen released within a predetermined appropriate range A first step of determining a flow rate of a gas containing oxygen as shown, a second step of introducing a gas into the reaction chamber while a wafer on which a semiconductor device is formed is installed in the reaction chamber, A third step of supplying high-frequency power to the antenna coil to generate high-density plasma in the reaction chamber; and introducing a gas containing oxygen into the reaction chamber at a flow rate determined in the first step. And a fourth step of performing etching for the semiconductor device formation.

According to this method, even when it is not possible to release oxygen enough to avoid the occurrence of an etch stop due to a variation in how the oxygen-containing member is attached, the generation of the etch stop can be achieved by supplying oxygen from the oxygen-containing gas. Can be reliably prevented.

Method of manufacturing a semi-conductor device [0017] The present invention includes a reaction chamber having an oxygen-containing member made of a material containing oxygen in the wall, and an antenna coil provided in proximity to the oxygen-containing member, said reaction chamber Gas supply means for introducing gas into the reactor, and plasma generation means for supplying high-frequency power to the antenna coil to generate any one of inductively coupled plasma, helicon wave plasma and ECR plasma in the reaction chamber And a method for manufacturing a semiconductor device using a device having light emission intensity detection means for detecting the emission intensity of O in the plasma, wherein a wafer on which the semiconductor device is formed is placed in the reaction chamber. In the state
A first step of introducing gas into the reaction chamber, a second step of generating plasma in the reaction chamber by the plasma generation means, and performing etching to form a hole in a part of the wafer; A third step of stopping the etching of the next wafer when the value detected by the light emission intensity detecting means is such that an etching stop occurs in which the etching is discontinuously stopped from a state where the etching is proceeding at a substantially constant speed; And

In this case, the gas supply means supplies a fluorocarbon-based gas, the emission intensity detection means also detects the emission intensity of F in the plasma, and the emission intensity of the O Calculating a light emission intensity ratio between the light emission intensity and the light emission intensity of F. In the third step, when the light emission intensity ratio calculated by the calculation means is in a condition that the etch stop occurs, the next wafer Is preferably stopped.

With these methods, it is possible to prevent the occurrence of defective products due to the occurrence of etch stop.

The method for manufacturing a semiconductor device according to the present invention is a method for manufacturing a semiconductor device on a substrate, wherein the oxygen-containing member is heated in a reaction chamber having an oxygen-containing member in a wall portion. A first step of supplying oxygen (O) from the containing member into the reaction chamber;
A second step of installing a wafer having a substrate, a silicon oxide film formed on the substrate, and a mask formed on the silicon oxide film; and carbon (C) and fluorine (C) in the reaction chamber. F) and contains an inert gas.
A third step of introducing a suitable etching gas;
A high-density plasma of 1 × 10 ¹¹ / cm ³ or more is generated in the vicinity of the wafer in the reaction chamber, and dry etching is performed to form a hole in the silicon oxide film below the opening of the mask. The fourth step is such that the concentration ratio of O and C in the plasma is C-
Deposits containing C-bonds are generated, and the etching is performed at a substantially constant speed. The etching is discontinuously stopped so that an etch stop does not occur. This is performed while controlling the amount of oxygen released from the oxygen-containing member.

The method for manufacturing a semiconductor device according to the present invention is a method for manufacturing a semiconductor device on a substrate, wherein the oxygen-containing member is heated in a reaction chamber having an oxygen-containing member in a wall portion. A first step of supplying oxygen (O) from the containing member into the reaction chamber;
A second step of installing a wafer having a substrate, a silicon oxide film formed on the substrate, and a mask formed on the silicon oxide film; and carbon (C) and fluorine (C) in the reaction chamber. F) and contains an inert gas.
A third step of introducing a suitable etching gas;
A high-density plasma of 1 × 10 ¹¹ / cm ³ or more is generated in the vicinity of the wafer in the reaction chamber, and dry etching is performed to form a hole in the silicon oxide film below the opening of the mask. The fourth step is such that the concentration ratio of O and F in the plasma is C-
Deposits containing C-bonds are generated, and the etching is performed at a substantially constant speed. The etching is discontinuously stopped so that an etch stop does not occur. This is performed while controlling the amount of oxygen released from the oxygen-containing member.

The method for manufacturing a semiconductor device according to the present invention is a method for manufacturing a semiconductor device on a substrate, wherein the oxygen-containing member is heated in a reaction chamber having an oxygen-containing member in a wall portion. A first step of supplying oxygen (O) from the containing member into the reaction chamber;
A second step of installing a wafer having a substrate, a silicon oxide film formed on the substrate, and a mask formed on the silicon oxide film; and carbon (C) and fluorine (C) in the reaction chamber. F) and contains an inert gas.
A third step of introducing a suitable etching gas;
A high-density plasma of 1 × 10 ¹¹ / cm ³ or more is generated in the vicinity of the wafer in the reaction chamber, and dry etching is performed to form a hole in the silicon oxide film below the opening of the mask. The fourth step is such that the concentration ratio of O, C and F in the plasma is such that the high-density plasma forms a deposit containing CC bonds on the bottom surface of the hole; The amount of oxygen released from the oxygen-containing member is set so as to be within a predetermined appropriate range for preventing an etch stop in which the etching stops discontinuously from a state where the etching is proceeding at a substantially constant speed. It is performed while controlling.

According to the above-described method for manufacturing a semiconductor device, the hole can be penetrated while avoiding the occurrence of the etch stop.

[0024] After the upper Symbol hole penetrates, on the substrate it is preferable to adjust the concentration of O in the plasma to be deposited is a carbon-containing product.

[0025] the proper range of the light-emitting intensity of the O in the plasma for the upper Symbol etch stop does not occur is obtained in advance,
The fourth step is characterized in that while measuring the emission intensity of O in the plasma, the concentration of O in the plasma is adjusted so that the emission intensity of O is within the appropriate range. preferable.

The upper Symbol etch stop to previously obtain beforehand the proper range of the ratio of the emission intensity of the emission intensity and F of O in the plasma for not occur, in the third step, fluorocarbon gas, and fluorocarbon-based Either one of the mixed gas of the gas and the inert gas is introduced into the reaction chamber, and in the fourth step, the emission intensity of O is measured while measuring the emission intensity of O and the emission intensity of F from the plasma. The concentration ratio between O and F in the plasma can be adjusted so that the ratio between the intensity and the emission intensity of F is within a predetermined appropriate range. In this case, the appropriate range of the concentration ratio between O and F in the plasma is preferably 4 to 10.

[0027] In the above SL third step, fluorocarbon gas, and either one of a gas mixture of fluorocarbon gas and inert gas is introduced into the reaction chamber, said first
In the fourth step, an appropriate range of the ratio between the emission intensity of O in the plasma and the emission intensity of C ₂ for preventing the occurrence of the etch stop is determined in advance, and the emission intensity of O from the plasma and the emission ratio of C ₂ are determined. While measuring the light emission intensity, the concentration ratio between O and C in the plasma may be adjusted so that the ratio between the light emission intensity of O and the light emission intensity of C ₂ is within a predetermined appropriate range. it can.

The previously seeking proper range of the ratio of the emission intensity of the emission intensity and C ₂ of O in the plasma for the upper Symbol etch stop does not occur in advance, in the third step, fluorocarbon gas, and fluorocarbon Either one of the mixed gas of the system gas and the inert gas is introduced into the reaction chamber, and in the fourth step, while measuring the emission intensity of O from the plasma and the emission intensity of C ₂ , Etching while adjusting the concentration ratio of O and C in the plasma so that the ratio of the emission intensity of C _{2 to} the emission intensity of C ₂ is within a predetermined appropriate range, and after the hole has penetrated. , on the substrate to adjust the concentration of O in the plasma to be deposited is a carbon-containing products
it can.

[0029] and the appropriate range of the ratio of the emission intensity of the emission intensity and F of O in the plasma for the upper Symbol etch stop does not occur, the appropriate range of the ratio of the emission intensity of the emission intensity and C ₂ O-advance In the third step, one of a fluorocarbon-based gas and a mixed gas of a fluorocarbon-based gas and an inert gas is introduced into the reaction chamber.
In the fourth step, the ratio between the emission intensity of O and the emission intensity of F is preset while measuring the emission intensity of O, the emission intensity of F, and the emission intensity of C ₂ from the plasma. The concentration ratio of O, F and C in the plasma is adjusted so that the ratio is within an appropriate range and the ratio between the emission intensity of O and the emission intensity of C ₂ is within a preset appropriate range.
be able to.

[0030] and the appropriate range of the ratio of the emission intensity of the emission intensity and F of O in the plasma for the upper Symbol etch stop does not occur, the appropriate range of the ratio of the emission intensity of the emission intensity and C ₂ O-advance In the third step, one of a fluorocarbon-based gas and a mixed gas of a fluorocarbon-based gas and an inert gas is introduced into the reaction chamber.
In the fourth step, the ratio between the emission intensity of O and the emission intensity of F is preset while measuring the emission intensity of O, the emission intensity of F, and the emission intensity of C ₂ from the plasma. Etching while adjusting the concentration ratio of O, F and C in the plasma so as to be within an appropriate range and the ratio of the emission intensity of O to the emission intensity of C ₂ is within a preset appropriate range. At the same time, the concentration of O in the plasma can be adjusted so that a carbon-containing product is deposited on the substrate after the holes have penetrated .

In the first step, the oxygen-containing part
By heating the temperature of the material to the range of 180 to 300 ° C,
Supplying oxygen (O) from the oxygen-containing member into the reaction chamber
Is preferred.

[0032] In the above SL fourth step is to introduce an oxygen-containing gas to the reaction chamber, and it is possible to adjust the amount of gas containing oxygen.

The above Symbol reaction chamber, leave further provided at least one of a carbon-containing member and a fluorine-containing member, in the fourth step, of the carbon and fluorine from each member By controlling at least one of the emission amounts, the concentration ratio of O, F, and C in the plasma can be adjusted.

[0034] In the above SL fourth step, adjusting the concentration ratio in the plasma O, F and C by introducing the reaction of carbon in the indoor, fluorine and gas containing at least any one of oxygen Can be.

[0035] In the above SL third step, the reaction _{chamber, CF 4, C 2 F 6} , C 3 F 8, C 4 F 8, C 5 F 8
And a gas containing at least one of C ₆ F ₆ .

[0036] In the above SL third step, the reaction _{chamber, C x F y O z (} x, y , and z component ratio) it is preferable to introduce a gas containing a compound represented by the.

According to this method, the concentration of O, F and C in the plasma can be adjusted with one kind of gas, so that the number of mass flow controllers can be reduced, and the equipment cost can be reduced and control can be performed. Can be simplified.

[0038] and the opening and the aspect ratio of the entire hole of the upper SL mask 4 above, when the diameter of the hole is 1μm or less, a large effect of the present invention applied.

[0039]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the relationship between the concentration ratio of carbon, fluorine, and oxygen in plasma and the etch stop according to the present embodiment will be described with reference to the drawings with reference to a number of experimental data.

FIG. 1 is a diagram for explaining the configuration of a semiconductor device manufacturing apparatus used in an experiment. In FIG. 1, 1a is a lower frame of a chamber surrounding the reaction chamber, 1b is an upper frame of the chamber, 2A is a quartz dome (oxygen-containing member) constituting a central portion of the chamber, and 3 is wound around the outer periphery of the quartz dome 2A. An antenna coil, 4 a first matching device for high-frequency power supplied to the antenna coil 3, 5 a first high-frequency power supply, 7 an upper electrode made of polysilicon, 6 a top heater for heating the upper electrode 7, 8 is a gas inlet, 9 is a substrate to be processed, 10 is a lower electrode, 12 is a lower electrode 10
, A second high-frequency power supply, 14 a turbo molecular pump, 15 a dry pump, 17 a plasma, 18 an optical fiber for passing light from the plasma 17, 19 is an emission spectrometer, 21
Is an alumina cylinder for protecting the antenna coil 3, 22 is a cooling ring, 23 is a quartz wafer clamp, 24 is a dome heater disposed at the lower end of the alumina cylinder 21 for heating the quartz dome 2A, and 25 is a reaction chamber. Each shows a quartz liner surrounding the lower part of FIG. The gas inlet 8 is configured so that various gases necessary for etching are supplied from a gas supply system (not shown), and the flow rates of the various gases can be adjusted to desired values by a flow meter and a control valve. Is configured.

As shown in FIG. 1, the lower frame 1 of the chamber
a, a quartz dome 2A and an upper frame 1b of the chamber form a reaction chamber, and the reaction chamber is evacuated by a turbo molecular pump 14 and a dry pump 15. A lower electrode 10 is provided in the reaction chamber, and a substrate 9 as a workpiece is provided on the lower electrode 10. The upper electrode 7 is configured so that the temperature can be adjusted by the top heater 6.
A is configured so that the temperature can be adjusted by the dome heater 24.

When the substrate 9 is processed, a fluorocarbon-based gas, for example, a gas containing C ₂ F ₆ is introduced into the reaction chamber from the gas inlet 8 at a flow rate of 40 sccm, and no O ₂ gas is added. With the pressure in the reaction chamber set to 5 mTorr (0.67 Pa), the antenna coil 3 is
, A high-frequency power of about 2700 W is applied as a source power, and the reflected power of the high-frequency power is suppressed by the first matching device 4, thereby generating a plasma 17 inside the reaction chamber. Then, a high-frequency power of about 1300 W is applied as a bias power to the lower electrode 10 by the second high-frequency power supply 13, and the reflected power of the high-frequency power is suppressed by the second matching device 12, so that the bias voltage for the plasma 17 on the substrate 9 is reduced Apply. Then, a region to be processed, for example, an interlayer insulating film on the substrate 9 is etched by ions accelerated by the bias voltage to form a hole. For example, C ₂ F ₆ is decomposed in the plasma to generate C
x Fy radical (x = 0, 1, 2,..., x = 0, 1,
2) and silicon oxide constituting the interlayer insulating film react with each other, and the etching proceeds while maintaining a high etching selectivity with respect to the underlying silicon substrate. In particular, this device
It is configured to generate high-density plasma in a high vacuum of the order of 10 mTorr, and to realize anisotropic etching without forming a sidewall protective film even during hole formation.

FIGS. 2A and 2B and FIGS.
(B) is a diagram showing emission spectra obtained as a result of plasma emission analysis performed in connection with the present invention. In each case, the vertical axis indicates emission intensity, and the horizontal axis indicates wavelength (wave number).
2 (a) and 2 (b) show the emission spectra when processing was performed smoothly without any etch stop during etching, and FIG. 2 (a) shows wavelengths at which O and F are peaks (respectively). 774 nm and 777 nm), and FIG. 2B shows an emission spectrum near a wavelength at which C ₂ has a peak. 3 (a) and 3 (b) show emission spectra when an etch stop occurs during etching and no through hole is formed, and FIG. 3 (a) shows O, O,
FIG. 3B shows an emission spectrum near the wavelength at which F peaks, and FIG. 3B shows an emission spectrum near the wavelength at which C ₂ peaks. 2 and 3
Although not shown in the figure, a peak of SiF is also observed. No other substance peaks were observed.

Here, in the following description, the emission intensity is compared by the value of the peak, and the width of the peak is ignored.

When comparing FIG. 2 (a) and FIG. 3 (a),
It is shown that the emission intensity of O is weak when an etch stop occurs. It is also shown that the larger the O / F emission intensity ratio, the less etch stop occurs.
A comparison between FIG. 2B and FIG. 3B shows that when an etch stop occurs, the emission intensity of C ₂ is large. However, FIGS. 2 (a) and 2 (b) and FIGS.
Whether the tendency shown in (b) is significant or not must be determined with reference to other data described later.

Generally, when a silicon oxide film is etched, O generated by decomposition of SiO ₂ reacts with C generated by decomposition of a fluorocarbon gas as an etching gas to form CO, CO ₂ , CF, etc. Is said to occur. In order to detect the end point of the etching, a change in the amount of CO in the plasma is observed. In the case of etching by the apparatus shown in FIG.
O and CO ₂ were hardly present. This is considered to be because fluorocarbon is efficiently separated into C and F because extremely high dissociation efficiency is realized in the plasma formed in this apparatus.

FIGS. 4A and 4B show the relationship between the center position and the end position of the substrate, which was used to check the bonding state of the deposits deposited on the bottom surface of the hole during the etching for forming the hole. It is a columnar graph which shows the analysis result of ESCA. In the figure, columns having different hatching patterns indicate different ratios of interatomic bonds. Also, FIG. The ESCA analysis results of Sample Nos. 1 to 3 are shown in FIG. 4 to 6 show the results of ESCA analysis. Sample No. 1 is a general condition (upper electrode temperature 260 ° C., quartz dome wall temperature 220 ° C.,
Etching was performed at a source power of 2700 W and an O ₂ flow rate of 0 sccm), and no etch stop occurred. Sample No. No. 2 was etched by changing only the wall temperature of the quartz dome 2A to 180 ° C. from the above general conditions, and an etch stop occurred. Sample No.
Sample No. 3 was etched while controlling the temperature of the upper electrode 7 at 240 ° C. with the source power set at 2500 W, and no etch stop occurred. Sample No. 4
Has a source power of 2500 W and an O ₂ flow rate of 4 sccm
And no etch stop occurred. Sample No. Sample No. 5 was etched under the condition that the source power was 2500 W and the flow rate of O ₂ was ₂ sccm, and no etch stop occurred. Sample No. No. 6 was etched by changing only the source power to 2500 W from the above general conditions, and an etch stop occurred.

Table 1 below is obtained by summarizing the above experimental results.

[0049]

[Table 1]

FIGS. 5 (a) and 5 (b) correspond to FIGS.
Sample No. shown in FIG. It is a figure which shows the result of having analyzed the component of the deposit thing deposited on the bottom face of a hole about the same sample as 1-6.

FIGS. 4 (a) and 4 (b) and FIGS.
As can be seen from the comparison of (b), although the deposit deposited on the bottom surface of the hole contains a considerable amount of C, O, F, and Si, the bonding state of these components is C
Most of -C bonds are present, and F and Si seem to exist in a free state.

FIG. 6 is a diagram showing the source power dependency of the light emission intensity of O, F and C ₂ , and FIG. 7 is a diagram showing the source power dependency of the light emission intensity ratio of O / F and C ₂ / F. FIG. As can be seen from FIG. 6, the emission intensity of O increases as the source power increases. The cause is that the quartz dome 2A is easily etched, so that the quartz dome 2A
This is probably because oxygen is easily released from.
Further, the emission intensity of F is slightly increased as the source power is increased. This is because C ₂ in plasma
It seems natural because the degree of dissociation of F ₆ increases.
The emission intensity of C ₂ little change is observed even with changes in the source power. As a result, as shown in FIG. 7, the O / F emission intensity ratio increases as the source power increases. Also, the emission intensity ratio of C ₂ / F decreases as the source power increases, but this is not a remarkable tendency.

FIG. 8 is a diagram showing the wall temperature dependence of the emission intensity of O, F and C ₂ on the wall of the quartz dome 2A. FIG. 9 is a graph showing the emission intensity ratio of O / F and the emission intensity ratio of C ₂ / F. It is a figure which shows wall temperature dependence. As can be seen from FIG. 8, the emission intensity of O increases as the wall temperature of the dome increases. The cause is
It is considered that the deposits attached to the quartz dome 2A are heated and volatilized easily, and as a result, oxygen is easily released from the quartz dome 2A. In addition, the higher the wall temperature of the dome, the smaller the light emission intensity of C ₂ and F becomes. As a result, as shown in FIG. 9, the emission intensity ratio of O / F increases as the source power increases, but the emission intensity ratio of C ₂ / F does not show a significant change. In the experiment under these conditions, the dome wall temperature was 20
At 0 ° C. or lower, an etch stop occurred, but when the dome wall temperature exceeded 200 ° C., no etch stop occurred.

FIGS. 10A to 10C show a state in which a normal through hole is formed when dry etching for forming a contact hole in an interlayer insulating film on a silicon substrate is performed, and an etch stop occurs to form a through hole. 4 is an SEM photograph showing a state where no hole is formed and a state where over-etching is performed after a through hole is formed. 3A and 3B show a state where the photoresist mask has been removed, and FIG. 3C shows a state where the photoresist mask remains.

Here, the cause of the occurrence of the etch stop during the etching will be considered based on the data shown in FIGS.

First, the etch stop in question is a so-called microloading effect (RIE lag) caused by a continuous decrease in the etch rate.
And different. Also, the hole diameter at the bottom when the etch stop shown in FIG.
The diameter is almost the same as that of the normal through hole shown in FIG.

Next, it is said that the formation of holes in the silicon oxide film when a fluorocarbon gas is used as an etching gas is performed by the following action.

While the hole is opened in the silicon oxide film, the C-rich CF compound is deposited on the bottom of the hole as described above. On the other hand, when a damaged layer is formed in the silicon oxide film below the deposit by ion irradiation,
SiO ₂ is decomposed to generate Si and O. Then, the deposits are removed by the reaction between Si, O and C, F in the deposits, and the etching of the silicon oxide film proceeds. That is, the etching proceeds downward because the action of removing the deposit and the action of removing the silicon oxide film is stronger than the action of depositing on the bottom of the hole.

However, for example, the aspect ratio of the hole becomes 4 or more, and the diameter of the hole becomes about 1 μm.
The following problems arise as the degree of integration of semiconductor devices increases. As the hole becomes deeper, the incident angle of ions with respect to the bottom surface of the hole becomes narrower, so that the amount of incident ions is reduced,
The etching action becomes weak. For this reason, it is presumed that the depositing action of the deposit becomes stronger than the etching action, and the etching stops (according to the above condition (a)).
Also, under the conditions performed here, the sediment at the bottom of the hole is:
It appears that most are -CC-polymers rather than CF compounds. Then, when such a carbon-based compound becomes -CC-polymer and is deposited on the bottom of the hole,
It is considered that a damaged layer is less likely to be formed in the lower silicon oxide film that is not decomposed even by ion collision, and an etch stop is caused (according to the above condition (c)). That is, when such a hard —CC—polymer is formed, it is necessary to decompose the main chain of the —CC—polymer by the presence of O.

However, when performing etching for forming a hole in a silicon oxide film on a silicon substrate,
It is often not added O ₂ gas to the fluorocarbon gas. This is because, as described above, O is generated by the decomposition of SiO ₂ , and therefore, even without adding O ₂ gas, the carbon-based residue that is to be deposited on the bottom of the hole is easily decomposed,
This is because the deposition can be prevented. Also, O
_{The fact} that no gas is added can surely prevent over-etching of the underlying silicon substrate (in other words, a high selectivity can be obtained). Therefore, when the contact hole is actually formed in the interlayer insulating film (silicon oxide film) using the apparatus shown in FIG. 1, even though the O ₂ gas is not added, as shown in FIGS. As described above, O exists in the plasma.

Here, as shown in FIGS. 2 and 3, it was found that the concentration of O in the plasma was higher when the etch stop did not occur during the etching than when the etch stop occurred. Therefore, there should be a source that supplies this excess O. As a result of further experiments, it was found that as shown in FIG. 6, when the temperature of the quartz dome was high (200 ° C.), no etch stop occurred. That is, it has been found that the variation in the phenomenon that the conventional etch stop occurs or does not occur depends on the temperature of the quartz dome.
This is considered to be because SiO ₂ constituting the quartz dome partially reacts by the application of the high-frequency power to generate SiF and O ₂ . On the other hand, deposits generated during plasma processing are deposited on the quartz dome, but when the temperature of the quartz dome is high, this deposit tends to volatilize, and as a result, the thickness of the deposit film on the surface decreases, It is estimated that O ₂ easily escapes from the quartz dome into the reaction chamber. It can be seen that this estimate would be nearly true in FIG.
Sample No. shown in FIG. This is supported by the wall temperature of the quartz dome 2 and the data shown in FIG.

The sample No. shown in FIG. As can be seen from the source power of No. 6 and the data shown in FIG. this is,
It is presumed that when the source power is large, the quartz dome is etched, so that the amount of O ₂ generated from the quartz dome also increases.

In summary, it was considered that the etch stop could be prevented by maintaining the amount of O _{2 in} the reaction chamber at an appropriate amount by some means. However, if the amount of the O ₂ gas is too large, the selectivity deteriorates because the silicon substrate is etched after the through holes are formed as described above.

Next, it was considered that the presence of elements other than O also had an important effect on the etching action. First, the ratio of F to O in plasma is also important. The reason is that if F is small, the etching effect is weak, and if F is too large, the etching effect on the underlying silicon substrate is strong, and the etching selectivity of the silicon oxide film is reduced.

If the ratio of C to O in the plasma is too large, an etch stop is likely to occur. If the ratio is too small, the etching selectivity between the silicon oxide film and the silicon substrate deteriorates.

Therefore, not only the amount of O ₂ gas but also the presence of O, F and C are required to prevent etching of the underlying silicon substrate as well as etch stop when forming holes in the silicon oxide film. The ratio is important.

FIG. 31 shows data indicating the emission intensity of O when oxygen gas is supplied using the quartz dome as a parameter while the temperature is kept constant (240 ° C.) using the coil power as a parameter. C ₂ F ₆ is used as an etching gas. The horizontal axis of the figure represents the flow rate of oxygen gas, and the vertical axis represents the emission intensity of O. Then, the value (negative value) of the oxygen flow at the point where the straight line connecting the measurement points where the coil power is constant intersects the line (horizontal axis) of the emission intensity 0 is the value of oxygen The amount of release is shown.
For example, the value of the intersection (x = -19.8) between the straight line connecting the measurement points of the coil power of 2700 W and the horizontal axis is the oxygen flow rate 1
It is considered that oxygen corresponding to 9.8 sccm was released.

As shown in the figure, the emission intensity of O increases as the flow rate of oxygen gas increases. This is because, as described above, the deposited matter adhering to the inner surface of the quartz dome is easily heated and volatilized, and as a result, oxygen in the quartz dome is easily released. From this data, it can be seen that the flow rate of the oxygen gas should be controlled so that the emission intensity of O becomes larger than a predetermined value (for example, 300 in an arbitrary unit shown in FIG. 2) at which no etch stop occurs.

It can also be seen that the emission intensity of O increases as the coil power increases. This is because, as described above, the deposit attached to the inner surface of the quartz dome is easily decomposed and volatilized, and as a result, oxygen in the quartz dome is easily released. Therefore, it is also understood that the coil power may be controlled so that the flow rate of oxygen is constant or the emission intensity of O becomes larger than a predetermined value at which no etch stop occurs without supplying oxygen gas.

It is expected that the etch stop can be more effectively prevented by appropriately adjusting the coil power and the oxygen flow rate.

FIG. 32 is data showing changes in the O / F emission intensity ratio and the C ₂ / F emission intensity ratio with respect to the coil power when the coil power is changed. The temperature of the quartz dome 2A was kept constant at 240 ° C., and oxygen gas was not supplied. C ₂ F ₆ is used as an etching gas. As shown in the figure, the O / F increases as the coil power increases.
Have a large emission intensity ratio. On the other hand, as the coil power increases, the emission intensity ratio of C ₂ / F decreases. This means that etch stop is less likely to occur as the coil power increases.

The present invention has been made based on the considerations supported by the above experimental data, and has the following embodiments.

(First Embodiment) In the present embodiment, a first method for adjusting the oxygen concentration in the reaction chamber using the semiconductor device manufacturing apparatus shown in FIG. 1 will be described.

When processing the substrate 9, a fluorocarbon-based gas such as C ₂ F ₆ gas or C ₄ F ₈ gas is introduced into the reaction chamber from the gas inlet 8, and the first high-frequency power supply 5 supplies the antenna coil 3. The plasma 17 is generated inside the reaction chamber by applying high-frequency power to the reaction chamber and suppressing the reflected power of the high-frequency power by the first matching device 4. The second high-frequency power supply 13 applies high-frequency power to the lower electrode 10 via the blocking capacitor 11, and suppresses the reflected power of the high-frequency power by the second matching device 12, thereby energizing the plasma 17 to the substrate 9. Is applied to the substrate 9. Then, the substrate 9 is etched by the ions accelerated by the bias voltage.

Here, the features of the manufacturing method of this embodiment are as follows.
The point is that the temperature inside the quartz dome 2A is controlled to about 180 ° C. while observing the emission intensity of O in the light emitted from the plasma 17 by the emission spectroscope 19.

FIG. 11 is a diagram showing the results of plasma emission analysis performed in connection with the present embodiment. In FIG. 11, the vertical axis indicates the emission intensity of O, here, for example, a wavelength of 777 n
The emission intensity of O of m (arbitrary unit) is shown, and the horizontal axis shows the temperature of the quartz dome. As an etching gas, C ₂
We are using the F _6. No oxygen gas was supplied. As shown in the figure, the wall temperature of the quartz dome is 160
The emission intensity of O gradually increases with an increase in temperature in the range of not more than ° C, whereas the emission intensity of O rapidly increases with an increase in the wall temperature of the quartz dome above 160 ° C. At 180 ° C. or higher, the O light emission intensity hardly changes even if the wall temperature of the quartz dome increases.

As described above, the oxygen that increases the light emission intensity is mainly oxygen in the quartz (silicon oxide) constituting the quartz dome 2A,
Is generated when the quartz dome 2 </ b> A is etched by the electric field of the antenna coil 3 wound around the outer circumference of the antenna, and is emitted into the plasma 17. In this case, when the wall temperature of the quartz dome is 160 ° C. or lower, since the reaction product is deposited on the inner wall surface of the quartz dome 2A, oxygen is not released into the plasma 17 and the emission intensity is small. When the temperature is 160 ° C. or higher, it is considered that the reaction products are less likely to be deposited on the inner wall surface of the quartz dome 2A, so that oxygen is released into the plasma 17 and the emission intensity increases.

The oxygen is released or not released from the inner wall surface of the quartz dome 2A depending on the range of the wall temperature of the quartz dome as described above, so that the following FIGS. 12 (a) and 12 (b) are obtained. The difference of the etching form shown in FIG.

FIG. 12A shows that the wall temperature of the quartz dome is 14
FIG. 4 is a cross-sectional view of the substrate 9 when etching is performed at 0 ° C. In FIG. 12A, 101 is a resist film, 102 is an oxide film, 103 is a silicon substrate, 104 is a contact hole, and 105 is a deposit. Under the conditions shown in FIG. 12A, the etching proceeds until the contact hole 104 reaches about the middle of the oxide film 102. However, when the contact hole 104 becomes deeper, the etching gas is polymerized in the plasma to contain a polymer containing carbon. A deposit containing carbon contained in the film or the resist film 101 starts to deposit on the bottom of the contact hole 104 in the opening. Then, since the deposit blocks the ions for etching, the etching stops halfway and the contact hole 104 is formed.
Is not penetrated.

On the other hand, FIG. 12B shows a shape when the contact hole 104 is formed by controlling the wall temperature of the quartz dome according to the present embodiment to 180 ° C. As described above, since oxygen is released from the inner wall surface of the quartz dome 2A under this condition, even if a deposit containing carbon is to be deposited on the bottom surface of the contact hole 104, the reaction between carbon and oxygen causes the deposit to be deposited. Is removed. Therefore, even if the contact hole 104 becomes deep, a deposit that would stop the etching halfway does not deposit on the bottom surface. Therefore, as shown in FIG. 12B, the contact hole 10 penetrating through the oxide film 102 and reaching the silicon substrate 103 is formed.
4 can be formed.

As described above, according to the present embodiment, by controlling the wall temperature of the quartz dome to 180 ° C. or more, it is possible to suppress the reaction products from adhering to the inner wall surface of the quartz dome 2A. During the etching, oxygen is stably supplied from the inner wall surface of the quartz dome 2A by the action of suppressing the adhesion of the reaction product, so that the contact hole having a high aspect ratio can be formed without stopping the etching in the middle. Can also be reliably formed.

In the present embodiment, the wall temperature of the quartz dome is detected from the emission intensity of O in the plasma 17, but the temperature may be detected by another method. For example, there is a method of empirically determining the relationship between the power supplied to the heater and the wall temperature of the quartz dome in advance to control the supplied power, and a method of directly attaching a thermometer to the quartz dome. Even if is used, processing such as etching can be performed smoothly.

Further, by detecting the O emission intensity in the plasma, the oxygen concentration in the plasma can be more directly controlled by utilizing the characteristics shown in FIG. 11 so that oxygen is reliably released from the quartz dome. Can be adjusted. FIG. 33 is a flowchart showing a procedure for preventing the etch stop by controlling the wall temperature of the quartz dome so that the emission intensity of O falls within an appropriate range.

In step ST11, the wafer is carried into the reaction chamber, and gas supply into the reaction chamber is started in step ST12. In step ST13, high-frequency power is applied to the antenna coil 3 and the lower electrode 10, and The etching of the upper oxide film is started. Then, in step ST14, the quartz dome 2A by the dome heater 24
Is performed, and the emission intensity of O is detected in step ST15. Next, in step ST16, it is determined whether or not the light emission intensity of O is equal to or more than a predetermined value 300 (value of an arbitrary unit shown in FIG. 2). On the other hand, if the emission intensity of O is less than 300 as determined in step ST16, the process proceeds to step ST18, where the heating amount of the quartz dome 2A is changed, and then the process returns to step ST14.

By the above control, the oxygen concentration in the reaction chamber can be controlled within a range where no etch stop occurs.

(Second Embodiment) In the present embodiment, a second method for adjusting an oxygen atmosphere in a reaction chamber using the semiconductor device manufacturing apparatus shown in FIG. 1 will be described.

In the present embodiment, the quartz dome 2A and the upper electrode 7 are heated by the heaters 6 and 24, thereby performing processing while controlling the temperature of the quartz dome 2A to 140 ° C. Then, a mixed gas of a fluorocarbon-based gas such as C ₂ F ₆ gas and C ₄ F ₈ gas and an oxygen gas having a flow rate of 5% or less of the flow rate of the fluorocarbon-based gas is introduced into the reaction chamber from the gas inlet 8. . Then, similarly to the above-described first embodiment, the plasma 17 is generated by the supply of the power from the first high-frequency power supply 5, and the substrate 9 is supplied by the supply of the high-frequency power from the second high-frequency power supply 13.
A bias voltage is applied thereon, and the substrate 9 is etched.

FIG. 13 is a diagram showing the results of plasma emission analysis performed in connection with the present embodiment. In FIG. 13, the vertical axis indicates the emission intensity of O, in this case, the wavelength is 777 n
The emission intensity of O of m (arbitrary unit) is shown, and the horizontal axis shows the temperature of the quartz dome. As shown in the figure, in the present embodiment, unlike the first embodiment, since oxygen gas is introduced into the reaction chamber, the emission intensity of O is increased accordingly. That is, the emission intensity of O is about 300 even at the wall temperature of the quartz dome of 140 ° C., and the value of the emission intensity of O is the same as that of the quartz without the introduction of oxygen gas in the first embodiment shown in FIG. This is the same value as the emission intensity of O at a dome wall temperature of 180 ° C. From this, it is expected that the same effect can be obtained by adding oxygen gas without heating the quartz dome to a high temperature to release a large amount of oxygen from the quartz dome.

In the present embodiment, etching for forming the contact hole 104 in the substrate 9 is performed in the same manner as in the first embodiment, while controlling the wall temperature of the quartz dome to 140 ° C. by introducing oxygen gas. Then, as shown in FIG. 12B, etching can be performed without depositing a deposit at the bottom of the contact hole 104 so as to stop the etching halfway, and the silicon substrate 103 penetrates the oxide film 102. The contact hole 104 which reaches was able to be formed.

In the present embodiment, C ₂ is contained inside the reaction chamber.
A fluorocarbon-based gas such as F ₆ gas or C ₄ F ₈ gas;
A mixed gas with an oxygen gas of 5% or less of the flow rate of the fluorocarbon-based gas was introduced, but C ₂ F ₆ gas and C ₄ F ₈
Fluorocarbon-based gas such as gas and Ar, He, Xe,
A mixed gas of a mixed gas of a rare gas (inert gas) such as Kr and an oxygen gas having a flow rate of 5% or less of the flow rate of the mixed gas may be used. Although oxygen gas is used as the additive gas, a gas composed of molecules partially containing oxygen, for example, CO gas, CO
_Two gases may be used.

(Third Embodiment) In this embodiment, a method for adjusting the oxygen concentration in the reaction chamber by the flow rate of oxygen gas will be described.

FIG. 14 is a view showing a configuration of a semiconductor device manufacturing apparatus according to the third embodiment. As shown in the figure,
The semiconductor device manufacturing apparatus according to the present embodiment has the same structure as the semiconductor device manufacturing apparatus shown in FIG. 1 except that a silicon nitride dome 2B is provided instead of the quartz dome 2A. However, although the O-ring 16 is shown in FIG. 14, although not shown in FIG. 1, the O-ring is provided at substantially the same position as in FIG.

In this embodiment, the silicon nitride dome 2B and the upper electrode 7 are heated by the heater 6, and the heating amount of the heater 6 is controlled so that the temperature of the silicon nitride dome 2B is maintained at 180 ° C. or higher. ing. Then, C ₂ F ₆ gas, C ₄
F ₈ is introduced a mixed gas of 5% or less oxygen gas at a flow rate of fluorocarbon-based gas and fluorocarbon gas such as a gas. As in the first embodiment, the plasma 17 is generated by the supply of the power from the first high-frequency power supply 5, and the bias voltage is applied to the substrate 9 by the supply of the high-frequency power from the second high-frequency power supply 13. Is applied to etch the substrate 9.

Next, FIG. 15 shows the difference in the plasma emission intensity of oxygen between the case where the silicon nitride dome containing no oxygen is used and the case where the quartz dome containing oxygen is used, performed in connection with the present embodiment. FIG. The wall temperature of the dome is 1
High temperature of 80 ° C. As described in the first embodiment, since the SiO ₂ is etched by the electric field of the antenna coil 3, oxygen is released from the inner wall surface of the quartz dome 2A, but the silicon nitride dome 2B is etched under the same conditions. Nothing is released from the inner wall surface. This is because of the constituent element Si—N of the silicon nitride dome 2B.
This is because the bond energy between them is larger than the bond energy between the constituent elements Si—O of quartz.

As described above, even if the silicon nitride dome containing no oxygen is etched, oxygen is not released from the side wall of the reaction chamber. Therefore, when the etching for forming the contact hole 104 in the substrate 9 is performed, the contact during the etching is not completed. A carbon-based deposit deposits on the bottom of the hole 104, and the etching stops halfway (see FIG. 12B).

At this time, the O of the quartz dome 2A shown in FIG.
When oxygen gas is added so as to exhibit an emission intensity of O equal to or higher than the emission intensity of carbon, the carbon-based deposit is removed, the etching proceeds without stopping halfway, and reaches the silicon substrate 103 through the oxide film 102. Contact hole 104
Was formed. FIG. 34 is a flowchart showing a procedure for preventing the etch stop by controlling the flow rate of the oxygen gas so that the emission intensity of O falls within an appropriate range.

In step ST21, the wafer is carried into the reaction chamber, and in step ST22, gas supply into the reaction chamber is started. In step ST23, high-frequency power is applied to the antenna coil 3 and the lower electrode 10 so that the wafer is supplied. The etching of the upper oxide film is started. Then, in step ST24, the opening degree of the control valve of the gas supply system is adjusted to control the flow rate of oxygen gas, and in step ST25, the emission intensity of O is detected. Next, in step ST26, it is determined whether or not the emission intensity of O is equal to or more than a predetermined value 300 (value of an arbitrary unit shown in FIG. 2).
Proceed to to continue the etching. On the other hand, step ST2
If the emission intensity of O is less than 300 in the determination in step 6, the process proceeds to step ST28, in which the flow rate of the oxygen gas is changed, and then returns to step ST24.

By the above control, the concentration of O in the plasma can be controlled within a range where no etch stop occurs.

By providing the silicon nitride dome 2B instead of the quartz dome 2A, oxygen is not released from the inner wall surface of the dome, so that the etching characteristics are not affected by the material constituting the inner wall of the reaction chamber. Therefore, since the concentration of O in the plasma can be controlled only by the flow rate of the oxygen gas, it can be said that the control is easy.

In this embodiment, silicon nitride is used as a material for forming the inner wall of the reaction chamber. However, instead of silicon nitride, any other insulator having no oxygen, such as aluminum nitride, silicon carbide, or AlF, is used. May be used.

In the present embodiment, C ₂ is contained inside the reaction chamber.
It is assumed that a mixed gas of a fluorocarbon gas such as F ₆ gas and C ₄ F ₈ gas and an oxygen gas having a flow rate of 5% or less of the flow rate of the fluorocarbon gas is introduced, but a mixture gas of C ₂ F ₆ gas, C ₄ F ₈ gas, etc. Fluorocarbon gas and Ar, He, Xe, K
A mixed gas of a mixed gas of a rare gas (inert gas) such as r and an oxygen gas having a flow rate of 5% or less of the flow rate of the mixed gas may be used. Although oxygen gas is used as the additive gas, a gas composed of molecules partially containing oxygen, for example, CO gas, CO
_Two gases may be used. Alternatively, a fluorocarbon-based gas such as C ₂ F ₆ gas or C ₄ F ₈ gas, and Ar, He, Xe, K
A mixed gas of a mixed gas of a rare gas (inert gas) such as r, a CO gas, a CO ₂ gas, and the like, and an oxygen gas having a flow rate of 5% or less of the mixed gas may be used.

(Fourth Embodiment) In the present embodiment, a method for determining whether or not the quartz dome can be used in the semiconductor device manufacturing apparatus shown in FIG. 1 will be described.

As described in the first embodiment, when the inner wall of the reaction chamber is made of a material containing oxygen, the amount of oxygen released from the reaction chamber greatly affects the etching characteristics. In the semiconductor device manufacturing apparatus shown in FIG. 1 used in the first embodiment, the quartz dome 2A is etched by the electric field of the antenna coil 3 wound on the quartz dome 2A, and oxygen is removed from the inner wall surface of the quartz dome 2A. Released into the plasma 17.

Therefore, for example, when the quartz dome is replaced during the life of the component, the inner wall surface may be changed due to a variation in the state of the quartz dome, such as a difference in the oxygen content of the quartz dome or a degree of unevenness due to the processing of the inner wall surface of the quartz dome. The amount of oxygen released from the semiconductor varies, greatly affecting the etching characteristics. In the conventional method, it has been found that there is a problem with the quartz dome after a product defect has occurred in which the product is actually processed and the etching is stopped halfway.

FIG. 16 shows the lot dependence of the emission intensity of O when the temperature of the quartz dome 2A is set to 180 ° C. in the semiconductor device manufacturing apparatus shown in FIG. The quartz domes S1, S2, and S3 are manufactured in exactly the same manner, but have different O emission intensities as shown in FIG. When a quartz dome S2 having a light emission intensity of O smaller than the standard value is used, oxygen is not sufficiently supplied from the inner wall surface thereof, and when etching for forming a contact hole is performed, the bottom of the contact hole is formed during the etching. A carbon-based deposit is deposited, and the etching stops halfway. Quartz domes S1, S whose emission intensity of O is larger than the standard value
When using No. 3, since oxygen is sufficiently supplied from the inner wall surface, carbon-based deposits at the bottom of the contact hole are removed, and the contact hole can be penetrated without stopping etching.

According to the present embodiment, when replacing a part such as a quartz dome in a semiconductor device manufacturing apparatus, the amount of oxygen released from the part is measured in advance before manufacturing a product. Device products can be prevented in advance.

(Fifth Embodiment) In this embodiment, when the quartz dome in the apparatus for manufacturing a semiconductor device shown in FIG. 1 is replaced, the manufacturing process of the semiconductor device depends on the state before the use of the quartz dome. The method of controlling the atmosphere in the reaction chamber in the above will be described.

As described in the first embodiment,
When the inner wall of the reaction chamber is made of a material containing oxygen, the amount of oxygen released from the reaction chamber greatly affects the etching characteristics. In the semiconductor device manufacturing apparatus shown in FIG. 1 used in the first embodiment, the quartz dome 2A is etched by the electric field of the antenna coil 3 wound on the quartz dome 2A, and oxygen is removed from the inner wall surface of the quartz dome 2A. Released into the plasma 17.

Therefore, for example, when the quartz dome is replaced during the life of the component, the degree of adhesion between the quartz dome and the antenna coil differs due to a difference in processing accuracy of the quartz dome or a difference in adjustment at the time of mounting. This allows
The amount of oxygen released from the inner wall surface of the quartz dome differs, which has a significant effect on the etching characteristics. In the conventional method, it has been found that there is a problem with the quartz dome after a product defect has occurred in which the product is actually processed and the etching is stopped halfway.

FIG. 17 is a circuit diagram showing the fourth embodiment shown in FIG.
In the case where the O emission intensity is dependent on the quartz lot as shown in FIG. 1, a quartz dome (for example, the quartz dome S3 in FIG. 16) having the O emission intensity larger than the standard value is manufactured in the semiconductor device shown in FIG. The graph shows the variation in the emission intensity of O when the device is attached to and detached from the device several times. As shown in the figure, although the same quartz dome is used, the emission intensity of O differs when the number of attachments changes, and the emission intensity of O sometimes becomes smaller than the standard value.

It is considered that the above-mentioned variation in the emission intensity of O is due to the fact that the degree of adhesion to the antenna coil differs depending on how the quartz dome is attached.
If etching for forming a contact hole is performed in this state, a carbon-based deposit is deposited on the bottom of the contact hole during the etching, and the etching stops on the way.

Here, in this embodiment, the emission intensity of O is detected when the quartz dome is replaced, and oxygen gas is added so that the emission intensity of O becomes larger than the standard value. The control for this may be as shown in the flowchart shown in FIG. As a result, the carbon-based deposit at the bottom of the contact hole is removed, and a contact hole that penetrates the oxide film and reaches the silicon substrate can be formed without stopping etching.

As described above, when replacing a quartz part in a semiconductor device manufacturing apparatus, the amount of oxygen released from the part is measured in advance before manufacturing a product. By introducing a gas and controlling the amount of the introduced oxygen gas, it is possible to prevent product defects in advance.

It is to be noted that the present invention is not limited to oxygen gas, and other gases containing oxygen may be used. The gas containing oxygen is not limited to the O ₂ gas, but a CO gas, a CO ₂ gas, or the like containing oxygen as a constituent element may be used.

The etching gas to which this specific example can be applied is
Preferably, the gas contains at least one of CF ₄ , C ₂ F ₆ , C ₃ F ₈ , C ₄ F ₈ and C ₆ F ₆ . In addition, a gas represented by C _x F _y O _z (for example, C
With ₂ like _{F 2 O 2, C 4 F} 6 O 3, C 6 F 4 O 2), the concentration ratio of oxygen also becomes possible to adjust at the same time. Therefore, it is possible to reduce the number of mass flow controllers required for adjusting the gas flow rate, thereby reducing equipment costs and simplifying control.

(Sixth Embodiment) In this embodiment, a method of manufacturing a semiconductor device while controlling the emission intensity ratio between O and F using the semiconductor device manufacturing apparatus shown in FIG. 1 will be described.

In the present embodiment, the quartz dome 2A and the upper electrode 7 are heated by the heaters 6 and 24, and processing is performed while controlling the temperature of the quartz dome 2A to 180 ° C. Then, a mixed gas of a fluorocarbon-based gas such as C ₂ F ₆ gas and C ₄ F ₈ gas and an oxygen gas having a flow rate of 5% or less of the flow rate of the fluorocarbon-based gas is introduced into the reaction chamber from the gas inlet 8. . Then, similarly to the above-described first embodiment, the plasma 17 is generated by the supply of the power from the first high-frequency power supply 5, and the substrate 9 is supplied by the supply of the high-frequency power from the second high-frequency power supply 13.
A bias voltage is applied thereon, and the substrate 9 is etched.

Here, the feature of this embodiment is that the emission intensity of O and F in the plasma 17 is detected by the emission spectroscope 19 through the optical fiber 18.

FIG. 18 is a diagram showing the relationship among the emission intensity of O in the plasma 17, the emission intensity of F, and the wall temperature of the quartz dome. The vertical axis in the figure represents the ratio of the emission intensity of oxygen (wavelength 777 nm) to the emission intensity of fluorine (wavelength 685 nm) (hereinafter simply referred to as the emission intensity ratio). As shown in the figure, the emission intensity ratio increases as the wall temperature of the quartz dome increases. This is because the amount of fluorine generated from the fluorocarbon-based gas, which is an etching gas, is constant regardless of the wall temperature of the quartz dome, whereas the amount of oxygen released from the inner wall surface of the quartz dome is the wall temperature of the quartz dome. The higher the value, the more it is. Then, when etching for forming the contact hole is performed, when the wall temperature of the quartz dome is 160 ° C., at a light emission intensity ratio of 20, a carbon-based deposit is deposited at the bottom of the contact hole due to a small amount of oxygen. Stops halfway and no contact hole is formed. On the other hand, the wall temperature of the quartz dome is 180 ° C
When the emission intensity ratio becomes 40 to 50 as described above, the etching proceeds without deposits being deposited on the bottom of the contact hole, and the contact hole can be penetrated. In particular, according to the method using the correlation between the wall temperature of the quartz dome and the light emission intensity ratio shown in FIG. 18, the method using the correlation between the wall temperature and the light emission intensity of the quartz dome shown in FIG. In comparison, there is an advantage that the state in which the wall temperature of the quartz dome has reached 180 ° C. can be reliably grasped from a change in the emission intensity ratio actually measured. The reason why the appropriate range of the O / F emission intensity ratio is different from the data shown in FIGS.
The emission intensity ratio of O / F in FIGS. 2 to 9 is determined by considering the ease of control, and the peak wavelength of O of 777 nm shown in FIGS. 2 and 3.
This is because the calculation is performed using the peak value of F at a wavelength of 774 nm which is close to.

Therefore, in the method of manufacturing a semiconductor device according to the present embodiment, etching is performed under the condition that the emission intensity ratio between O and F is 40 or more.

FIG. 19 is a block diagram schematically showing a configuration of a control system of the semiconductor device manufacturing apparatus according to the present embodiment. In the figure, reference numeral 21 denotes a reaction chamber including the devices shown in FIG. 1, 22 denotes an emission spectrometer, 23 denotes an A / D converter for converting an analog signal into a digital signal, and 24 denotes the operation of each member. An apparatus CPU for control, 25 is a transport system for transporting products into and out of the reaction chamber, and 26 is an alarm for notifying an abnormality.

FIG. 20 is a flowchart showing a control procedure performed by the apparatus CPU 24 shown in FIG. 19 when performing etching. Hereinafter, the etching process will be described with reference to FIG. 19 and along the flowchart of FIG.

First, in step ST1, the product is transported out of the reaction chamber 21 by the transport system 25, and the next product waiting for the etching process is transported into the reaction chamber 21. Then, in step ST2, etching of the product, for example, etching for forming a contact hole is started.

Next, in steps ST3 and ST4, the emission intensity in the plasma during the etching is measured by the emission spectrometer 2.
2 to detect. Here, the emission intensities of O and F are detected. The detected analog signal is converted into a digital signal by the A / D converter 23, and is taken into the device CPU 24. Then, in step ST6, the device CPU 24 calculates the emission intensity ratio between oxygen and fluorine.

Next, in step ST6, the light emission intensity ratio becomes 4
It is determined whether it is 0 or more, and if the light emission intensity ratio is 40 or more, the process proceeds to step ST7 to continue the etching. When the etching is completed, the process returns to the control in step ST1.

On the other hand, if the emission intensity ratio is less than 40 in the discrimination in step ST6, the etching that is currently in progress is continued, and when the etching is completed in step ST9, the product after the completion of etching is transferred to the reaction chamber by the transfer system 25. (Quartz dome) is transported outside, but the next product waiting for the etching process is not transported into the reaction chamber under the control of step ST9. Then, in step ST10, an alarm is generated from the alarm device 26 to notify that it is abnormal.

By using such a semiconductor device manufacturing apparatus and a semiconductor device manufacturing method, it is possible to prevent product defects. At the end of the etching in step ST8, a penetrating contact hole may be formed (the state shown in FIG. 12B), or the etching is stopped halfway without being penetrated (FIG. 1).
2 (a)).

In this embodiment, the emission intensities of O and F are measured and the ratio is used. However, the emission intensity of O alone may be used.

Further, as an application of this embodiment, etching may be performed while introducing oxygen gas so that etching is performed under the condition that the ratio of the emission intensity of O to the emission intensity of F is 40 or more. Good.

(Seventh Embodiment) In this embodiment, a method for manufacturing a semiconductor device while adjusting the concentration ratio of oxygen, fluorine and carbon in a reaction chamber using the semiconductor device manufacturing apparatus shown in FIG. explain.

FIG. 21 shows that the apparatus shown in FIG. 1 is used to adjust the RF power to 2700 W while using a fluorocarbon gas (C ₂ F ₆ gas in this case), to add a flow rate of the O ₂ gas to be added to the RF power and a quartz dome 2A. FIG. 5 is a diagram showing the O / F emission intensity ratio, which is the ratio between the O peak value and the F peak value in the emission spectrum when the temperature is changed. Then, the quartz dome 2A at a flow rate of O ₂ gas is 0 among the conditions shown in FIG. 21
Etch stop occurred only at temperatures of 220 ° C. and 230 ° C. That is, it can be seen that an etch stop has occurred when the O / F emission intensity ratio is 1.0 or less.
The O / F concentration ratio in the plasma at this time does not match this emission intensity ratio, but O / F in which no etch stop occurs in advance
Since the emission intensity ratio of O / F is known, by controlling the flow ratio between the O ₂ gas and the fluorocarbon gas so that the emission intensity ratio of O / F falls within an appropriate range where etch stop does not occur, the etch stop is performed. Can be formed while the contact hole is reliably avoided.

[0132] On the other hand, FIG. 22 is a 2300W RF power while using a fluorocarbon gas (C ₂ F ₆ gas in this case) using the apparatus shown in FIG. 1, and the flow rate of O ₂ gas added thereto, quartz shows the emission intensity ratio of O / C ₂ which is the ratio of the O peak value and C ₂ peak in the emission spectrum when varying the temperature of the dome 2A. FIG.
In the conditions shown in the figure, the O ₂ gas flow rate was 0 and the quartz dome 2
When the temperature of A is 160 ° C. and 180 ° C., the flow rate of the O ₂ gas is 1 sccm, and the temperature of the quartz dome 2A is 160 ° C. and 18 ° C.
At 0 ° C., an etch stop occurred when the flow rate of the O ₂ gas was ₂ sccm and the temperature of the quartz dome 2A was 160 ° C. That is, it can be seen that an etch stop occurs when the O / C ₂ emission intensity ratio is 19 or less. At this time, the concentration ratio of O / C in the plasma does not match the emission intensity ratio of O / C ₂ , but O / C in which an etch stop does not occur in advance.
Since the emission intensity ratio of C ₂ is known, the etch ratio is controlled by controlling the flow ratio of the O ₂ gas to the fluorocarbon gas so that the emission intensity ratio of O / C ₂ falls within an appropriate range where no etch stop occurs. The contact hole can be formed while reliably avoiding the stop. In the data shown in FIG. 22, the temperature at which the etch stop occurs is lower than the temperature shown in FIG. 21, but this is probably because the RF power is a little weak at 2300 W.

21 and 22, the control of the concentration ratio of the three components in the plasma such that the ratio of the emission intensities of C, F and O in the plasma is within an appropriate range. I know it is possible. However, when the type of etching gas such as fluorocarbon gas is determined, the concentration ratio between carbon and fluorine existing in the reaction chamber becomes substantially constant. Therefore, it is generally understood that the flow rate of the O ₂ gas should be controlled while measuring the O / F emission intensity ratio or the O / C ₂ emission intensity ratio. In this case, it is preferable to use the emission intensity ratio of O / C ₂ as a control parameter so that the effect of depositing the carbon-containing product at the bottom of the hole and the effect of removing it can be properly balanced. Can be controlled. However, FIG.
As shown in (b), since the wavelengths giving the peak values of O and C ₂ in the emission spectrum are significantly different, it takes time and effort to accurately determine the emission peak intensity ratio between the two. At that point, the wavelengths giving the peak values of O and F in the emission spectrum are very close, so that the emission peak intensity ratio between the two can be measured quickly and accurately. Further, as shown in FIG. 21, since the concentration ratio of carbon and fluorine by the type of fluorocarbon gas it can be regarded as almost constant, controlling the emission intensity ratio between O and F in place of the light emission intensity ratio between O and C ₂ Parameter Can be used as In this case, the O / F emission intensity ratio when the etch stop occurs shown in FIG. 21 actually represents the O / C ₂ emission intensity ratio at which the etch stop occurs, that is, the O / C concentration ratio in the plasma. You can also think. However, since the concentration of F itself affects the etching action in another functional aspect, it is necessary to prevent the etch stop within a range that does not impair the etching action.
The emission intensity ratio of / F can also be used as a control parameter.

From the relationship between the presence / absence of an etch stop and the emission intensity ratio of C, F, and O shown in the above data, in order to prevent the etch stop from occurring during the etching, C, F, O It is preferable that the concentration ratio be within the following range.

First, it is considered that the O / F concentration ratio is preferably 4 or more so that no etch stop occurs. On the other hand, if the O / F concentration ratio is too large, the etching selectivity between the silicon oxide film and the silicon substrate is deteriorated and the etching rate is lowered. That is, it is considered that the O / F concentration ratio is preferably 4 to 10.

Further, if the O / C concentration ratio in the plasma is too small, an etch stop occurs during the etching, so it is considered preferable that the O / C concentration ratio is 2 or more. On the other hand, if the concentration ratio of O / C in the plasma is too large, the etching selectivity between the silicon oxide film and the silicon substrate cannot be increased. That is, it seems that the O / C concentration ratio in the plasma is preferably 2 to 5.

Here, simply flowing O ₂ gas at a constant flow rate causes the concentration ratio of C, F, and O in the plasma in the reaction chamber to gradually deviate from an appropriate range as many wafers are processed. A situation in which an etch stop suddenly occurs cannot be avoided. This is because C, F, O in plasma
If the concentration ratio deviates even slightly from the optimum range, it is considered that the deviation accumulates. Therefore, by controlling the concentration ratio of C, F, and O in the plasma to be within an appropriate range, C, F, and O in the plasma are always controlled.
There is an advantage that the concentration ratio of F and O is kept in an appropriate range, and the etch stop can be more reliably prevented.

Here, there are the following methods for realizing the appropriate C, F, O concentration ratio as described above.

[0139] The first method is, as already explained, O ₂
This is a method of controlling the temperature of the quartz dome 2A without adding a gas. As a result of adjusting the concentration of O by this method, the concentration ratio of C and F to O can be maintained in appropriate ranges. For this method,
As described above.

However, only by controlling the heating of the quartz member, the conditions for realizing the appropriate range become narrow. Therefore, the following method is possible.

First, when the upper electrode 7 made of polysilicon is heated by the top heater 6, F directly reacts with polysilicon, that is, the effect that polysilicon absorbs F increases. For example, when the quartz dome 2A is heated to 220 ° C. without supplying the O ₂ gas, and the upper electrode 7 is heated and a source power of 2500 W is applied,
Although no etch stop occurred at 240 ° C.,
The result is that an etch stop occurs when heated to ° C. This is probably because the concentration ratio of F became low. Therefore, by controlling the heating of the upper electrode 7 (hereinafter, referred to as a polysilicon electrode) made of polysilicon by the top heater 6, the concentration ratio of F can be adjusted.

FIG. 35 shows a procedure for preventing the etch stop by controlling the heating amount of the quartz dome and the heating amount of the polysilicon electrode so that the O / F emission intensity ratio falls within an appropriate range. It is a flowchart.

In step ST31, the wafer is carried into the reaction chamber, and in step ST32, the supply of gas into the reaction chamber is started. In step ST33, high-frequency power is applied to the antenna coil 3 and the lower electrode 10, and The etching of the upper oxide film is started. Then, in step ST34, the quartz dome 2A by the dome heater 24
In step ST35, heating control of the polysilicon electrode by the top heater 6 is performed, and in step ST36, the emission intensities of O and F are detected. Next, in step ST37, it is determined whether or not the O / F emission intensity ratio is within an appropriate range.
Proceeding to T38, the etching is continued. On the other hand, if it is determined in step ST37 that the O / F emission intensity is not within the appropriate range, the process proceeds to step ST39, in which the heating amount of the quartz dome or the heating amount of the polysilicon electrode (or the heating amount of both) is changed. The process returns to step ST34.

By the above control, the O / F concentration ratio in the plasma can be controlled within a range where no etch stop occurs.

Further, a member containing carbon may be installed in the reaction chamber, and may be heated and controlled. For example, the top heater 7 is made of carbon (hereinafter, referred to as a carbon heater), and the amount of C released into the reaction chamber can be controlled by heating to adjust the concentration ratio of C in the plasma.

FIG. 36 shows the O / F emission intensity ratio and O / C
₉ is a flowchart showing a procedure for preventing an etch stop by controlling the heating amount of the quartz dome and the heating amount of the carbon heater so that the emission intensity ratio of No. ₂ falls within an appropriate range.

In step ST41, the wafer is loaded into the reaction chamber, and gas supply into the reaction chamber is started in step ST42. In step ST43, high-frequency power is applied to the antenna coil 3 and the lower electrode 10, and The etching of the upper oxide film is started. Thereafter, in step ST44, the quartz dome 2A by the dome heater 24
Is performed, and in step ST45, heating control of the carbon heater is performed. In step ST46, O,
The emission intensity of F and C ₂ is detected. Next, step ST4
7, it is determined whether the O / F emission intensity ratio is within an appropriate range. Then, in step ST48, it is determined whether the O / C ₂ emission intensity ratio is within an appropriate range. If it is within the proper range, the process proceeds to step ST49 to continue the etching. On the other hand, if the O / F emission intensity ratio or the O / C ₂ emission intensity ratio is not within the appropriate range, the process proceeds to step ST50, where the heating amount of the quartz dome or the heating amount of the carbon heater (or the heating amount of both) is reduced. After the change, the process returns to step ST44.

By the above control, the O / F concentration ratio and the O / C ₂ concentration ratio in the plasma can be controlled within a range in which no etch stop occurs.

In order to adjust the concentration ratio of C, F, and O, a gas containing at least one of these elements can be used as a reaction gas or an additive gas.

For example, CF ₄ , C ₂ F
_{6, C 3 F 8, C} 4 F 8, C ₅ gas containing at least one of a F ₈ and C ₆ F ₆ can be used. Further, CO gas or O ₂ gas may be added to C ₄ F ₈ . Further, by using a gas obtained by adding C ₄ F ₈ to C ₆ F ₆ as a reaction gas, the concentration ratio of C and F can be more finely adjusted.

If a gas represented by C _x F _y O _z (for example, C ₂ F ₂ O ₂ , C ₄ F ₆ O ₃ , C ₆ F ₄ O ₂ ) is used, toxicity is as high as that of CO gas. Without using a gas having a certain concentration, the concentration ratio of C, F, and O can be maintained in an appropriate range by a single reaction gas. Further, a fluorocarbon gas such as CF ₄ may be added to these gases.

In particular, when the above-described reaction gas and additive gas are used, a member whose surface exposed in the reaction chamber is made of quartz or carbon is not disposed in the reaction chamber, but only by controlling the gas flow rate. Alternatively, the concentration ratio of C, F, and O in the plasma may be appropriately adjusted.

(Eighth Embodiment) In this embodiment, an etch stop caused by the presence of aluminum ions in a reaction chamber will be described.

Generally, a metal film (particularly, an Al film for wiring,
When etching the i-film, Cu film, W film, Co film, etc., or when the metal film is exposed after etching other members (for example, silicon oxide film) on the metal film, the plasma in the reaction chamber is exposed. The phenomenon of metal scattering is seen. FIG.
(A) and (b) show the case where the Al film is etched and the case where the Si film is etched.
FIG. 4 is an emission spectrum diagram showing a result of plasma emission analysis when etching a substrate. In the data shown in FIG. 23A, Al ions not appearing in FIG. 23B are detected, confirming that Al ions are scattered in the plasma.

It is considered that the scattered metal adheres to the members in the chamber and combines with the etching species (F, 0). FIG. 24 is a diagram showing a result of analyzing the surfaces of the silicon top plate and the quartz dome in the chamber by XPS. In the figure, the horizontal axis represents the binding force (eV), and the vertical axis represents the analysis intensity. As shown in the figure, the presence of a substance having an Al-F bond in both members has been confirmed.

FIG. 25 is a cross-sectional view showing a model of an etch stop caused by scattering of Al into the reaction chamber. FIG. 26 is a flowchart showing a process in which an etch stop occurs. Hereinafter, a process in which an etch stop occurs will be described with reference to FIGS.

Here, an inductively-coupled plasma apparatus in which the chamber wall is composed of a quartz dome and a silicon top plate and two RF power supplies are used to apply high-frequency power to the induction coil and the lower electrode. The case of using is taken as an example. It is assumed that an interlayer insulating film made of a silicon oxide film is formed on a wafer, and plasma etching for forming a hole (via hole) reaching the Al wiring is performed in the interlayer insulating film. F ions and F ions generated by the decomposition of fluorocarbon are contained in the plasma.
Radicals and C ₂ ions are present. At this time, if there is a large-area hole (for example, a hole on a bonding pad), when the hole is penetrated, the surface of the large-area Al wiring is exposed. When Al ions are scattered in the plasma, F ions and Al ions in the plasma combine to form a compound AlF _x , which is deposited on a silicon top plate or a quartz dome. Due to the formation of AlF _x , the etching species (F) in the plasma is reduced, and C ₂ /
The F ratio increases. As a result, an etch stop occurs due to the operation described above in the embodiment. It is considered that such an etch stop occurs when the above condition (c) is satisfied.

However, an etch stop caused by such metal contamination is unlikely to occur by etching a hole having a high aspect ratio. FIG. 27 is a diagram illustrating a result obtained by using Monte Carlo simulation to determine a position where 1,000 ions are present in a hole. The abscissa in the figure represents the number of 1000 ions, and the ordinate represents the height from the bottom of the hole having a constant cross section as an aspect ratio. That is, the probability that ions are trapped in holes having a certain aspect ratio is a value obtained by dividing the number of ions below the position of the aspect ratio in FIG. 27 by the total number of ions.

FIG. 28 shows the probability that ions are trapped in holes based on the simulation results of FIG.
FIG. 9 is a diagram illustrating a calculation result of how the probability that ions scatter outside a hole changes depending on an aspect ratio. As shown in FIGS. 27 and 28, it can be understood that the higher the aspect ratio of the hole, the more difficult it is for Al ions to scatter outside the hole.

The reason for this is that, as shown in FIG. 29, when a hole having a high aspect ratio is formed, most of the Al ions scattered from the Al wiring are deposited on the side surface of the hole as a deposit, and It is probably because they are trapped inside.

Therefore, when performing plasma etching including a hole having a low aspect ratio such as a hole on a bonding pad, there is a high probability that an etch stop of such a form will occur. That is, every time a hole on the bonding pad is opened, metal ions scatter and gradually accumulate in the reaction chamber, so that the number of etching species in the reaction chamber is reduced. A stop will occur.

Next, in order to avoid such an etch stop caused by metal contamination, the following means are effective.

The first method is a method in which the surface of the metal member is not exposed in the chamber. If the surface of the metal member is exposed in the chamber, the bonding between the etching species and the metal occurs on the surface of the metal member, resulting in a shortage of the etching species (such as F) and the surface of the metal wiring is exposed. This is because the same action as described above occurs. For example, there is an O-ring used for maintaining the airtightness of a chamber in which a metal is mixed, but the metal used in such a state also poses a problem. For example, the O-ring 16 in the apparatus shown in FIG. 14 has conventionally used a material in which a metal such as aluminum is mixed in silicon rubber, but in the present embodiment, the O-ring 16 is made of silicon rubber containing no metal. It is constituted by such as. As a result, it was confirmed that etch stop due to metal contamination can be reliably prevented.
Further, it is preferable that a member such as an O-ring including ceramic using a metal oxide is not provided in the chamber.

The second method is a method in which metal ions are cleaned in the reaction chamber by fluorocarbon plasma or fluorocarbon plasma in the reaction chamber. FIG.
FIG. 4 is a diagram showing the results of an experiment in which the degree of recovery when cleaning with fluorocarbon plasma was performed under conditions in which an etch stop occurred. The abscissa in the figure represents the cleaning time, and the ordinate in the figure represents the depth of the hole that has progressed until an etch stop occurs when re-etching is performed. The hole is formed in an oxide film having a thickness of 1 μm. I am trying to do it. This means that a large amount of metal ions remain in the reaction chamber when the etch stop occurs, and this is gradually cleaned with fluorocarbon plasma. As shown in FIG. 30, it is shown that the etching depth is increased every time the cleaning time passes, and the original state where the concentration of the metal ions is slight is recovered in 8 hours. This means that contamination by metal ions released when etching a hole having an aspect ratio of about 2.8 is removed by cleaning for about 50 seconds per wafer, and does not lead to an etch stop. And experiments.

As a modification of the second method, instead of performing the cleaning, the time of the main etching by the fluorocarbon plasma at the time of the next wafer processing is intentionally lengthened, and the metal ions released into the reaction chamber in the previous processing are deliberately increased. It is a method of removing. Specifically, there is a method in which the etching rate is reduced by lowering the bias power applied to the substrate to a value lower than normal conditions.

Representative examples of metals in this embodiment include Al, Ti, Cu, W, and Co. However, the present invention is not limited thereto, and those reactive with the etching species (such as F) are applicable.

(Other Embodiments) The region to be processed to which the present invention can be applied exhibits a great effect particularly when the region is a film containing oxygen, for example, a film composed of an oxide such as a silicon oxide film or an alumina film. Can be. Since a film composed of such an oxide releases oxygen when it is etched, it is necessary to use this to maintain a high etching selectivity with a silicon substrate or a polysilicon film. This is because there is a risk of causing a stop.

In each of the above embodiments, the side wall of the chamber is made of a quartz dome or a silicon nitride dome. However, the present invention is not limited to such an embodiment, and a case where a quartz dome or the like is installed in the chamber is used. May be. In that case, the reaction chamber is a portion surrounded by a quartz dome or the like,
The case where oxygen is generated from the outer wall surface such as a quartz dome is also included.

In each of the above embodiments, only the quartz dome is exemplified as the oxygen-containing member, but the dome may be made of another oxide-based inorganic material.

In each of the above embodiments, only the etching as the plasma processing is described, but the present invention is not limited to such an embodiment. For example, the plasma processing of the present invention can be applied to a case where plasma processing is performed in an ammonia gas or nitrogen gas atmosphere to introduce nitrogen into a semiconductor substrate or metal wiring at the bottom of a contact hole.

[0171]

According to the method of manufacturing a semiconductor device of the present invention, when forming a hole by plasma etching, the concentration of O in the plasma in the reaction chamber is adjusted so that an etch stop does not occur. Therefore, the etch stop can be prevented by surely removing the -CC-polymer deposited on the bottom of the hole.

According to the method of manufacturing a semiconductor device of the present invention,
When replacing the oxygen-containing member in the reaction chamber, after configuring the reaction chamber with an oxygen-containing member showing a desired oxygen release amount,
Since plasma etching is performed in the reaction chamber,
Even when the amount of released oxygen varies due to the attachment of the oxygen-containing member forming the reaction chamber, the semiconductor device can be manufactured without causing an etch stop.

According to the method of manufacturing a semiconductor device of the present invention,
When replacing the oxygen-containing member in the reaction chamber, the flow rate of the gas containing oxygen indicating the desired oxygen release amount was determined, and then the plasma etching was performed under the flow rate.
Even when the amount of oxygen released from the inner wall surface is insufficient due to a variation in how to attach the oxygen-containing member, the semiconductor device can be manufactured without causing an etch stop.

According to the method of manufacturing a semiconductor device of the present invention,
When plasma etching is performed in the reaction chamber, the etching of the next workpiece is stopped when the emission intensity of O or the ratio of the emission intensity of O to the emission intensity of F is a condition that causes an etch stop. Therefore, it is possible to prevent the occurrence of defective products due to the etch stop.

According to the method of manufacturing a semiconductor device of the present invention,
After performing plasma etching in the reaction chamber, an etching gas is allowed to flow for a predetermined time in order to remove metal ions in the reaction chamber, thereby preventing occurrence of an etch stop due to accumulation of metal ions. be able to.

[Brief description of the drawings]

FIG. 1 is a block diagram partially showing an example of a configuration of a semiconductor device manufacturing apparatus used in the present invention in a cross-sectional view.

FIG. 2 is a diagram showing an emission spectrum when processing can be performed smoothly without generating an etch stop.

FIG. 3 is a diagram showing an emission spectrum when an etch stop occurs and a through hole is not formed.

FIG. 4 is a diagram showing the results of ESCA analysis at the center position and the end position of the substrates of Samples 1 to 6 for examining the bonding state of the deposits deposited on the bottom surface of the hole.

5 is a diagram showing the results of analyzing the components of the deposits deposited on the bottom surfaces of the holes for samples 1 to 6 shown in FIG.

FIG. 6 is a diagram showing data relating to source power dependence of emission intensities of O, F and C ₂ .

FIG. 7 is a diagram showing the source power dependence of the O / F emission intensity ratio and the C ₂ / F emission intensity ratio.

FIG. 8 is a diagram showing the dependence of the emission intensities of O, F and C ₂ on the wall temperature of the dome.

FIG. 9 is a diagram showing the dependence of the luminous intensity ratio of O / F and the luminous intensity ratio of C ₂ / F on the wall temperature of the dome.

FIG. 10 is a copy of an SEM photograph showing a state in which a normal through hole is formed in dry etching, a state in which an etch stop has occurred, and a state in which over etching is performed after a through hole is formed. .

FIG. 11 is a view showing the wall temperature dependence of the emission intensity of O obtained by oxygen emission analysis according to the first embodiment of the quartz dome.

FIG. 12 is a cross-sectional view illustrating a state where an etch stop has occurred and a state where a through hole has been formed in etching for forming a contact hole according to the first embodiment.

FIG. 13 is a characteristic diagram showing the dependence of the emission intensity of O obtained by oxygen emission analysis according to the second embodiment on the wall temperature of the quartz dome.

FIG. 14 is a block diagram partially showing a configuration of an apparatus for manufacturing a semiconductor device according to a third embodiment in a cross-sectional view.

FIG. 15 is a diagram showing a difference in emission intensity of O when using a silicon nitride dome and a quartz dome obtained in an experiment performed on the third embodiment.

FIG. 16 shows that the temperature of the quartz dome according to the fourth embodiment is 1
It is a figure which shows the lot dependence of the quartz dome of the light emission intensity of O at 80 degreeC.

FIG. 17 shows a variation in O light emission intensity when a quartz dome having a light emission intensity of O greater than a standard value according to the fifth embodiment is attached to and detached from a semiconductor device manufacturing apparatus several times. FIG.

FIG. 18 is a characteristic diagram showing the wall temperature dependence of the ratio of the emission intensity of O to the emission intensity of F according to the sixth embodiment of the quartz dome. .

FIG. 19 is a control system diagram of an apparatus for manufacturing a semiconductor device according to a sixth embodiment.

FIG. 20 is a flowchart illustrating a procedure of an etching process of the semiconductor device according to the sixth embodiment.

FIG. 21 shows C ₂ in a _second specific example of the seventh embodiment.
FIG. 4 is a diagram showing O / F emission intensity ratios when the flow rate of O ₂ gas added to F ₆ gas and the temperature of the quartz dome are changed.

FIG. 22 shows C ₂ in the second specific example of the seventh embodiment;
FIG. 6 is a diagram showing the O / C ₂ emission intensity ratio when the flow rate of O ₂ gas added to F ₆ gas and the temperature of the quartz dome are changed.

FIG. 23 is an emission spectrum diagram showing results of plasma emission analysis when etching an Al film and etching an Si substrate in the eighth embodiment.

FIG. 24 is a diagram showing a result of analyzing a surface of a silicon top plate and a surface of a quartz dome in a chamber according to the eighth embodiment by XPS.

FIG. 25 is a cross-sectional view illustrating a model of an etch stop caused by scattering of Al into a reaction chamber according to the eighth embodiment.

FIG. 26 is a flowchart illustrating a process in which an etch stop occurs in the eighth embodiment.

FIG. 27 is a diagram showing a result obtained by Monte Carlo simulation of a position where 1000 ions are present in a hole in the eighth embodiment when 1000 ions are present in the hole.

FIG. 28 is a diagram showing a calculation result of how the probability that ions are trapped in holes and the probability that ions scatter outside holes change depending on the aspect ratio based on the simulation result of FIG. 27; It is.

FIG. 29 is a cross-sectional view showing a state in which Al ions scattered from Al wiring in the eighth embodiment are deposited as deposits on side surfaces of holes.

FIG. 30 is a diagram showing a result of an experiment for examining a degree of recovery when cleaning with fluorocarbon plasma is performed under a condition in which an etch stop occurs in the eighth embodiment.

FIG. 31 is a diagram showing the emission intensity of O when oxygen gas is supplied while using a quartz dome to keep its temperature constant, using coil power as a parameter.

FIG. 32 is a diagram showing changes in the O / F emission intensity ratio and the C ₂ / F emission intensity ratio with respect to the coil power when the coil power is changed.

FIG. 33 is a flowchart illustrating a procedure for controlling the wall temperature of the quartz dome so that the emission intensity of O falls within an appropriate range in the first embodiment.

FIG. 34 is a flowchart showing a procedure for controlling the flow rate of oxygen gas so that the emission intensity of O falls within an appropriate range in the third embodiment.

FIG. 35 is a flowchart illustrating a procedure for controlling the heating amount of the quartz dome and the heating amount of the polysilicon electrode so that the O / F emission intensity ratio falls within an appropriate range in the seventh embodiment.

FIG. 36 shows a procedure for controlling the heating amount of the quartz dome and the heating amount of the carbon heater so that the O / F emission intensity ratio and the C ₂ / O emission intensity ratio fall within appropriate ranges in the seventh embodiment. It is a flowchart figure which shows.

FIG. 37 is a diagram showing the progress of etching in three cases: normal etching, microloading, and etch stop.

[Explanation of symbols]

 Reference Signs List 1a Chamber lower frame 1b Chamber upper frame 2 Quartz dome (oxygen-containing member) 3 Antenna coil 4 First matching device 5 Second high-frequency power supply 6 Heater 7 Upper electrode 8 Gas inlet 9 Substrate 10 Lower electrode 11 Blocking capacitor 12 2 matching device 13 second high frequency power supply 14 turbo molecular pump 15 dry pump 16 O-ring 17 plasma 18 optical fiber 19 emission spectrometer 21 alumina cylinder 22 cooling ring 23 wafer clamp 24 dome heater 25 quartz liner 101 resist film 102 oxide film 103 silicon substrate 104 Contact hole 105 Depot

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Satoshi Nakagawa 1-1, Yukicho, Takatsuki-shi, Osaka Prefecture Inside Matsushita Electronics Corporation (72) Inventor Shoji Matsumoto 1-1, Yukicho, Takatsuki-shi, Osaka Matsushita Inside the Electronic Industry Co., Ltd. (72) Inventor Yoji Bito 1-1, Sachimachi, Takatsuki City, Osaka Prefecture Inside the Matsushita Electronic Industry Co., Ltd. (56) References JP-A-10-150019 (JP, A) JP-A-8 JP-A-227876 (JP, A) JP-A-9-181172 (JP, A) JP-A-7-263409 (JP, A) JP-A-7-263421 (JP, A) JP-A-7-335626 (JP, A) JP-A-9-181044 (JP, A) JP-A-9-92642 (JP, A) JP-A-5-315262 (JP, A) JP-A-7-122544 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) H01L 21/3065 C23C 16/507 C23F 4/00

Claims (22)

(57) [Claims] 1. A method for manufacturing a semiconductor device using a device including a reaction chamber having an oxygen-containing member made of a material containing oxygen in a wall portion and an antenna coil provided in proximity to the oxygen-containing member. When exchanging the oxygen-containing member, the amount of oxygen released from the oxygen-containing member is measured, and the flow rate of the oxygen-containing gas is changed so as to indicate the amount of oxygen released within a predetermined appropriate range. A second step of introducing a gas into the reaction chamber while a wafer on which a semiconductor device is formed is placed in the reaction chamber; and supplying high-frequency power to the antenna coil. A third step of generating high-density plasma in the reaction chamber; and introducing an oxygen-containing gas into the reaction chamber at a flow rate determined in the first step while forming an edge for forming a semiconductor device. Method of manufacturing a semiconductor device characterized in that it comprises a fourth step of performing ring. 2. A reaction chamber having an oxygen-containing member made of an oxygen-containing material in a wall portion, an antenna coil provided close to the oxygen-containing member, and a gas supply for introducing gas into the reaction chamber. Means for supplying high-frequency power to the antenna coil and causing any one of inductively coupled plasma, helicon wave plasma and ECR plasma to enter the reaction chamber.
A method of manufacturing a semiconductor device, comprising: using a device having plasma generation means for generating a laser beam; and light emission intensity detection means for detecting the emission intensity of O in the plasma. A first step of introducing a gas into the reaction chamber with the wafer to be placed in the reaction chamber; and generating plasma in the reaction chamber by the plasma generation means to form a hole in a part of the wafer. A second step of performing etching for performing the etching, and the detection value of the emission intensity detecting means is a condition under which an etch stop occurs in which the etching is discontinuously stopped from a state where the etching is proceeding at a substantially constant speed. A third step of stopping the etching of the next wafer in some cases. 3. The method of manufacturing a semiconductor device according to claim 2 , wherein said gas supply means supplies a fluorocarbon-based gas, and said emission intensity detection means also detects the emission intensity of F in said plasma. Detecting the light emission intensity ratio between the O light emission intensity and the F light emission intensity. In the third step, the light emission intensity ratio calculated by the calculation means is used as the etch stop. A method of manufacturing a semiconductor device, wherein etching of a next wafer is stopped when the conditions for the occurrence of pitting occur. 4. A method for manufacturing a semiconductor device on a substrate, comprising: heating an oxygen-containing member in a reaction chamber having an oxygen-containing member in a wall portion; A first step of supplying (O), a wafer having a substrate, a silicon oxide film formed on the substrate, and a mask formed on the silicon oxide film is set in the reaction chamber; A second step, wherein the reaction chamber contains carbon (C) and fluorine (F) ;
A third step of introducing an etching gas containing no inert gas; and generating a high-density plasma of 1 × 10 ¹¹ / cm ³ or more in the vicinity of the wafer in the reaction chamber. A fourth step of performing dry etching so that a hole is formed below the opening of the mask, wherein the fourth step is such that the concentration ratio of O and C in the plasma is adjusted by the high-density plasma. C on the bottom of the above hole
A deposit including a -C bond is generated, and the etching is performed at a substantially constant speed. The etching is discontinuously stopped. The etching is stopped within a predetermined appropriate range so that an etch stop does not occur. A method of manufacturing a semiconductor device, wherein the method is performed while controlling the amount of oxygen released from the oxygen-containing member. 5. A method for manufacturing a semiconductor device on a substrate, comprising: heating an oxygen-containing member in a reaction chamber having an oxygen-containing member in a wall portion; A first step of supplying (O), a wafer having a substrate, a silicon oxide film formed on the substrate, and a mask formed on the silicon oxide film is set in the reaction chamber; A second step, wherein the reaction chamber contains carbon (C) and fluorine (F) ;
A third step of introducing an etching gas containing no inert gas; and generating a high-density plasma of 1 × 10 ¹¹ / cm ³ or more in the vicinity of the wafer in the reaction chamber. A fourth step of performing dry etching so that a hole is formed below an opening of the mask, wherein the fourth step is such that the concentration ratio of O and F in the plasma is adjusted by the high-density plasma. C on the bottom of the above hole
A deposit including a -C bond is generated, and the etching is performed at a substantially constant speed. The etching is discontinuously stopped. The etching is stopped within a predetermined appropriate range so that an etch stop does not occur. A method of manufacturing a semiconductor device, wherein the method is performed while controlling the amount of oxygen released from the oxygen-containing member. 6. A method for manufacturing a semiconductor device on a substrate, comprising: heating an oxygen-containing member in a reaction chamber having an oxygen-containing member in a wall portion; A first step of supplying (O), a wafer having a substrate, a silicon oxide film formed on the substrate, and a mask formed on the silicon oxide film is set in the reaction chamber; A second step, wherein the reaction chamber contains carbon (C) and fluorine (F) ;
A third step of introducing an etching gas containing no inert gas; and generating a high-density plasma of 1 × 10 ¹¹ / cm ³ or more in the vicinity of the wafer in the reaction chamber. A fourth step of performing dry etching so as to form a hole below the opening of the mask, wherein the fourth step includes O, C, and F in the plasma.
An etch stop in which a deposit containing a C--C bond is generated on the bottom surface of the hole by the high-density plasma and the etching stops discontinuously from a state where the etching is proceeding at a substantially constant speed. A process for controlling the amount of oxygen released from the oxygen-containing member so as to be within a predetermined appropriate range for preventing generation of a semiconductor device. 7. The method for manufacturing a semiconductor device according to claim 4 , wherein after the hole penetrates, the carbon-containing product is deposited on the substrate. A method for manufacturing a semiconductor device, comprising adjusting the concentration of O in plasma. 8. The method of manufacturing a semiconductor device according to claim 4 , wherein the O in the plasma for preventing the etch stop from occurring.
In the fourth step, the emission intensity of O in the plasma is measured while measuring the emission intensity of O in the plasma so that the emission intensity of O is in the appropriate range. A method of manufacturing a semiconductor device, comprising: adjusting a concentration of a semiconductor device. 9. The method of manufacturing a semiconductor device according to claim 4 , wherein O in the plasma for preventing the occurrence of the etch stop.
An appropriate range of the ratio between the luminescence intensity of F and the luminescence intensity of F is determined in advance, and in the third step, one of a fluorocarbon-based gas and a mixed gas of a fluorocarbon-based gas and an inert gas is reacted. In the fourth step, the ratio between the emission intensity of O and the emission intensity of F is set in advance while measuring the emission intensity of O and the emission intensity of F from the plasma. A method for manufacturing a semiconductor device, comprising adjusting the concentration ratio of O and F in the plasma so that the concentration is within the range. 10. The method of manufacturing a semiconductor device according to claim 9 , wherein the appropriate range of the concentration ratio between O and F in the plasma is 4 to 4.
10. A method for manufacturing a semiconductor device according to claim 10. 11. The method of manufacturing a semiconductor device according to claim 4 , wherein in the third step, a mixture of a fluorocarbon-based gas and a mixed gas of a fluorocarbon-based gas and an inert gas is used. Either one of them is introduced into the reaction chamber, and in the fourth step, an appropriate range of the ratio between the emission intensity of O in the plasma and the emission intensity of C ₂ in order to prevent the occurrence of the etch stop is obtained in advance. While measuring the emission intensity of O and the emission intensity of C ₂ from the plasma, the emission intensity of the plasma is adjusted so that the ratio of the emission intensity of O to the emission intensity of C ₂ is within a predetermined appropriate range. A method for manufacturing a semiconductor device, comprising: adjusting the concentration ratio of O and C. 12. The method of manufacturing a semiconductor device according to claim 4 , wherein the O in the plasma for preventing the etch stop from occurring.
An appropriate range of the ratio of the luminescence intensity of C _{2 to} the luminescence intensity of C ₂ is determined in advance, and in the third step, one of fluorocarbon-based gas and a mixed gas of fluorocarbon-based gas and inert gas is used. In the fourth step, while measuring the emission intensity of O and the emission intensity of C ₂ from the plasma, the ratio between the emission intensity of O and the emission intensity of C ₂ is set in advance. The etching is performed while adjusting the concentration ratio of O and C in the plasma so as to be within the proper range, and after the holes penetrate, the carbon-containing product is deposited on the substrate. Adjusting the concentration of O in the plasma. 13. The method for manufacturing a semiconductor device according to claim 11 , wherein an appropriate range of the concentration ratio of C to O in the plasma is 4 to 4.
10. A method for manufacturing a semiconductor device according to claim 10. 14. The method of manufacturing a semiconductor device according to claim 4 , wherein the O in the plasma for preventing the etch stop from occurring.
An appropriate range of the ratio between the emission intensity of F and the emission intensity of F and an appropriate range of the ratio of the emission intensity of O to the emission intensity of C ₂ are determined in advance . In the third step, the fluorocarbon-based gas and Either a mixed gas of a fluorocarbon-based gas and an inert gas is introduced into the reaction chamber, and in the fourth step, the emission intensity of O from the plasma, the emission intensity of F, and the emission intensity of C ₂ Is measured, the ratio between the emission intensity of O and the emission intensity of F is within a preset appropriate range, and the ratio of the emission intensity of O to the emission intensity of C ₂ is set in advance. A method for manufacturing a semiconductor device, comprising: adjusting the concentration ratio of O, F, and C in the plasma so that the concentration is within the range. 15. The method for manufacturing a semiconductor device according to claim 4 , wherein O in the plasma for preventing the etch stop from occurring.
An appropriate range of the ratio between the emission intensity of F and the emission intensity of F and an appropriate range of the ratio of the emission intensity of O to the emission intensity of C ₂ are determined in advance . In the third step, the fluorocarbon-based gas and Either a mixed gas of a fluorocarbon-based gas and an inert gas is introduced into the reaction chamber, and in the fourth step, the emission intensity of O from the plasma, the emission intensity of F, and the emission intensity of C ₂ Is measured, the ratio between the emission intensity of O and the emission intensity of F is within a preset appropriate range, and the ratio of the emission intensity of O to the emission intensity of C ₂ is set in advance. The etching is performed while adjusting the concentration ratio of O, F and C in the plasma so as to be within the range, and the carbon-containing product is deposited on the substrate after the hole penetrates. Adjust O concentration in plasma The method of manufacturing a semiconductor device according to claim Rukoto. 16. A method according to claim 4, wherein:
In the method of manufacturing a semiconductor device described above, in the first step, the temperature of the oxygen-containing member is set to 1
The oxygen-containing member is heated to a temperature in the range of 80 ° C to 300 ° C.
And wherein the supply of oxygen (O) to the reaction chamber from
Semiconductor device manufacturing method. 17. The method of manufacturing a semiconductor device according to any one of claims 4-13, in the fourth step, introducing a gas containing oxygen to the reaction chamber, and containing oxygen A method for manufacturing a semiconductor device, comprising adjusting an amount of gas. 18. The method according to claim 14 or 15, wherein, in the reaction chamber, and further provided at least any one Cormorants <br/> Chi carbon-containing member and a fluorine-containing member Place, in the fourth step, by controlling one emission at least one of carbon and off <br/> Tsu containing from each member, the concentration ratio of the O in the plasma, F and C A method for manufacturing a semiconductor device, comprising: 19. The method for manufacturing a semiconductor device according to claim 14 , wherein in the fourth step, a gas containing at least one of carbon, fluorine and oxygen is introduced into the reaction chamber. A method for manufacturing a semiconductor device, comprising adjusting the concentration ratio of O, F, and C in plasma. 20. The method of manufacturing a semiconductor device according to claim 4 , wherein in the third step, CF ₄ , C is contained in the reaction chamber.
_{2 F 6, C 3 F 8} , C 4 F 8, C 5 method of manufacturing a semiconductor device, which comprises introducing a gas containing at least any one of F ₈ and C ₆ F _6. 21. The method of manufacturing a semiconductor device according to claim 4 , wherein in the third step, C _x F _y O is contained in the reaction chamber.
_A method for manufacturing a semiconductor device, comprising introducing a gas containing a compound represented by _z (x, y and z are component ratios). 22. The method of manufacturing a semiconductor device according to any one of claims 4 to 21, opening and aspect ratio of the entire hole of the mask 4 or more, the diameter of the hole is 1μm A method for manufacturing a semiconductor device, comprising: