JP2002299439A - Semiconductor device and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing semiconductor device by which the working accuracy of an insulating film by etching can be improved easily and to provide a semiconductor device manufactured by the method. SOLUTION: To the surface of a first polymethylsiloxan film 2c formed on a semiconductor substrate 3, varnish 2 which is the liquid raw material of a second polymethylsiloxan film 2 formed as a second low-dielectric constant interlayer insulating film is applied. Then the varnish 2c is fixed on the film 2c by heating the varnish 2 step by step while the varnish 2 is maintained at about 80 deg.C and 200 deg.C for about one minute, respectively. Successively, an electron beam is projected toward the varnish 2 by respectively adjusting the irradiation energy and dose of the beam to about 6 keV and about 500 μC/cm<2> , while the varnish 2 is arranged in a pressure-reduced atmosphere of about 0.1 Torr containing N2 as the main ingredient and maintained at about 400 deg.C. Consequently, a decomposed layer 2b which is slower in etched rate than those in both end sections of the second polymethylsiloxan film 2 is formed in the intermediate section of the film 2 in the thickness direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method of manufacturing a semiconductor device and a semiconductor device manufactured by the method.

[0002]

2. Description of the Related Art In recent years, as wiring dimensions of wirings (underlying substrate wirings) have become smaller due to miniaturization of semiconductor elements (devices), the capacitance between wirings has increased, and the operating speed of devices using this semiconductor device has been reduced. It is starting to have a big impact. In order to increase the speed of a device to be miniaturized, it is necessary to reduce the product of the wiring resistance and the capacitance between lines. For this purpose, for example, the underlying substrate wiring is made of copper (Cu) wiring having a low resistivity, and in order to reduce the capacitance between the wirings, a low dielectric constant insulating film is provided around the underlying substrate wiring as a thin film. It is indispensable to employ a high interlayer insulating film.

Conventionally, as an interlayer insulating film of a semiconductor device,
A silicon oxide film formed by a thermal CVD method, a plasma CVD method, or the like has been used. Conventional plasma CV
A general silicon oxide film (P-
The relative dielectric constant of the (SiO ₂ film) was about 4.1. Also,
The relative dielectric constant of the silicon oxide film (FSG film) whose dielectric constant is reduced by adding fluorine (F ₂ ) to the silicon oxide film is 3.
This is about 3, which is the limit of the low relative dielectric constant of the insulating film (interlayer insulating film) generated (formed) by the thermal CVD method or the plasma CVD method.

On the other hand, according to recent research results,
It is practically possible to reduce the relative dielectric constant to about 2.4 to 2.8 by applying a low dielectric constant film made of a material such as an organic silicon oxide film or an organic substance containing no silicon to the interlayer insulating film. I understand. As a result, it is required to apply a low dielectric constant film made of a material such as an organic silicon oxide film or an organic substance not containing silicon to the interlayer insulating film.

[0005] Most of these organic silicon oxide films and low dielectric constant interlayer insulating films made of materials such as organic substances not containing silicon are characterized in that they are formed exclusively by a coating method. In the method of forming an interlayer insulating film by this coating method, first, a liquid material called a varnish in which a low-molecular component (precursor) of a substance constituting a desired film is dissolved in a solvent is applied onto a semiconductor substrate. Thereafter, the varnish is heated together with the semiconductor substrate to advance the volatilization (evaporation) of the solvent and the crosslinking reaction of the low-molecular component (precursor), thereby forming an interlayer insulating film as a thin film (firing). It is assumed that. The varnish and the semiconductor substrate have been heated using an electric furnace, a hot plate, or the like so that the temperatures thereof are maintained at a predetermined temperature.

The main parts of the conventional method for forming an interlayer insulating film are schematically shown in FIGS.
This will be described with reference to FIG.

First step: As shown in FIG. 3A, a varnish 102, which is a liquid raw material obtained by dissolving polymethylsiloxane as a raw material of the interlayer insulating film 102 in a solvent, is applied by a spin coat method using a coater as shown in FIG. , Semiconductor device 101
Is applied on the surface of a semiconductor substrate (wafer) 103 having a diameter of 8 inches.

Second step: The semiconductor substrate 103 is
As shown in (b), the hot plate 1 is placed in a posture in which the surface side on which the varnish (coating film) 102 is applied faces upward.
04. Then, the temperature of the varnish 102 is reduced to about 8
The temperature of the hot plate 104 is adjusted so as to be maintained at 0 ° C., the varnish 102 is heated together with the semiconductor substrate 103, and this state is maintained for about one minute. Thereby, the varnish 102 is subjected to the first heat treatment.

Third step: Subsequently, the varnish 1 is kept while the semiconductor substrate 103 is placed on the hot plate 104.
The temperature of the hot plate 104 is adjusted so that the temperature of the varnish 102 is maintained at about 200 ° C., and the varnish 102 is heated together with the semiconductor substrate 1, and this state is maintained for about 1 minute. Thus, the varnish 102 is subjected to a second heat treatment.

Fourth step: The semiconductor substrate 10
While the substrate 3 is placed on the hot plate 104, the temperature of the hot plate 104 is adjusted so that the temperature of the varnish 102 is maintained at about 400 ° C., and the varnish 102 is heated together with the semiconductor substrate 1. Hold the condition for about 30 minutes. Thus, the varnish 102 is subjected to a third heat treatment. In performing the third heat treatment, the varnish 102 is placed in a nitrogen atmosphere together with the semiconductor substrate 103.

By performing the heat treatments in the second to fourth steps described above, the semiconductor substrate 1 is formed in the first step.
The solvent and the like contained in the varnish 102, which is a liquid material of the polymethylsiloxane film applied on the substrate 03, are removed by evaporation. As a result, the varnish coating film 102 is fixed on the semiconductor substrate 103, and the polymethylsiloxane film 102 as an interlayer insulating film is formed on the semiconductor substrate 103. In this case, a polymethylsiloxane film 102 having a thickness of about 1 μm is formed.

As shown in FIG. 3C, the diameter of the polymethylsiloxane film 102 having a thickness of about 1 μm formed through the above-described first to fourth steps is measured using a CF-based gas. An etching process for forming a wiring hole (groove) 105 of about 0.175 μm was performed. As a result, a variation in the shape of the wiring hole 105 was observed between the central portion (center portion) and the peripheral portion (edge portion) of the 8-inch diameter semiconductor substrate 103. Specifically, the wiring hole 105b formed in the peripheral portion (edge portion) of the semiconductor substrate 103 is etched about 10% deeper than the wiring hole 105a formed in the central portion (center portion). This may be because the etching rate (etching rate) at the peripheral portion of the semiconductor substrate 103 is about 10% faster than the etching rate at the central portion.

That is, although the polymethylsiloxane film 102 formed through the first to fourth steps has a different etching rate depending on the position although the whole is formed of the same material, Each wiring hole 105a, 1
As shown in FIG. 05b, variations in the dimensions of the processed portion formed by etching, which are not negligible in maintaining the performance of the semiconductor device 101 at a predetermined level, have occurred.

[0014]

As described above, in the conventional method of forming an insulating film, even if the entire insulating film is formed of the same material, the etching rate varies depending on the position. Dimensions outside the permissible range that cannot be ignored occur.

In the semiconductor device 101 (semiconductor substrate 1)
(On the surface 03), it is increasingly difficult to control the etching rate to be substantially uniform as the elements become finer, more highly integrated, and the semiconductor substrate 103 becomes larger in diameter. .

Accordingly, it is an object of the present invention to provide a method of manufacturing a semiconductor device capable of easily improving the processing accuracy of an insulating film by etching, and a semiconductor device manufactured by the method.

[0017]

In order to solve the above-mentioned problems, a method of manufacturing a semiconductor device according to the present invention comprises the steps of forming an insulating film on a semiconductor substrate and performing a heat treatment on the insulating film. Irradiating the insulating film with an electron beam to form a deteriorated layer in a part of the insulating film in the thickness direction; and forming a damaged layer along the thickness direction of the insulating film on which the deteriorated layer is formed. Forming a concave portion for wiring by selectively etching the insulating film and the deteriorated layer.

In this method of manufacturing a semiconductor device, the insulating film formed on the semiconductor substrate is irradiated with an electron beam while heating the insulating film, so that the insulating film is formed in one direction in the thickness direction of the insulating film. A deteriorated layer is formed in the portion, and the insulating film and the deteriorated layer are selectively etched along the thickness direction of the insulating film on which the deteriorated layer is formed, thereby forming a wiring recess. Accordingly, the wiring recess is etched from the insulating film toward the semiconductor substrate, and when the bottom reaches the deteriorated layer, the etching rate in the non-transformed portion of the insulating film depends on the position where the wiring recess is formed. The difference in the formation rate (working rate) of the wiring concave portion due to the difference in the (etching rate) can be easily adjusted so as to almost eliminate the difference.

In carrying out the method of manufacturing a semiconductor device according to the present invention, some of the steps may be set as described below.

A part of the insulating film in the thickness direction is altered so that the rate of etching of the altered layer formed on the insulating film is lower than the rate of etching of the insulating film.

A deteriorated layer of the insulating film is formed at an intermediate portion in the thickness direction of the insulating film.

The insulating film is formed using a low dielectric constant insulating film.

The low dielectric constant film is formed using polymethylsiloxane.

The insulating film is formed by a coating method.

[0025] The material of the insulating film is applied on the semiconductor substrate, and the material of the insulating film is heated and fixed on the semiconductor substrate so that the temperature thereof increases stepwise. After forming the insulating film on the semiconductor substrate, by irradiating the electron beam toward the insulating film while heating the insulating film so that the temperature is maintained at a higher temperature, An altered layer is formed in a part of the insulating film in the thickness direction.

When irradiating the electron beam, heat treatment is performed so that the temperature of the insulating film is 200 ° C. or more and less than 500 ° C.

When irradiating the electron beam, the irradiation amount of the electron beam is set to 500 μC / cm ² or more.

When irradiating the electron beam, the insulating film is placed under a predetermined reduced pressure atmosphere.

A buried wiring containing copper as a main component is formed in the low dielectric constant insulating film.

In carrying out the method of manufacturing a semiconductor device according to the present invention, by setting a part of the process to various settings as described above, the desired formation position and size of the wiring recess, or In accordance with the desired performance of the insulating film and the like, the formation environment of the deteriorated layer, the material for forming the insulating film, and the like are set so as to be suitable for them, and the formation speed (working speed) of the wiring concave portion is appropriately adjusted. Can be set to state.

In order to solve the above problems, a semiconductor device according to the present invention comprises a semiconductor substrate, an insulating film formed on the semiconductor substrate, and a wiring recess formed in the insulating film. In the semiconductor device provided, the insulating film has a deteriorated layer formed by heat treatment and irradiation with an electron beam in a part of the insulating film in a thickness direction thereof.

In this semiconductor device, an altered layer is formed on a part of the insulating film formed on the semiconductor substrate in the thickness direction. As a result, the wiring recesses are etched from the insulating film toward the semiconductor substrate, and when the bottom reaches the deteriorated layer, the etching rate in the non-transformed portion of the insulating film (depending on the position where it is formed) ( The film is formed so as to be easily adjusted so that the difference in the forming speed (processing speed) due to the difference in the etching rate (working rate) is almost eliminated.

Further, in the semiconductor device according to the present invention,
A part of the insulating film provided therein may be set as described below.

[0034] The etching rate of the altered layer of the insulating film is formed to be lower than the etching rate of the insulating film.

In the insulating film, the deteriorated layer is formed at an intermediate portion in the thickness direction of the insulating film.

The insulating film is formed using a low dielectric constant insulating film.

The low dielectric constant insulating film is composed mainly of polymethylsiloxane.

A buried wiring containing copper as a main component is formed in the low dielectric constant insulating film.

By setting a part of the insulating film included in the semiconductor device according to the present invention to various settings as described above, a desired position and size of the wiring recess, or a desired insulating film can be obtained. The formation environment of the deteriorated layer, the material for forming the insulating film, and the like are set according to the performance and the like, and the formation speed (working speed) of the wiring concave portion is set to an appropriate state. .

[0040]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method of manufacturing a semiconductor device according to one embodiment of the present invention and a semiconductor device manufactured by this manufacturing method will be described with reference to FIGS. 1 (a) to 1 (c) and FIG. It will be described based on.

In the method of manufacturing a semiconductor device according to the present embodiment, the step of forming the insulating film 2 on the semiconductor substrate 3 includes the steps of:
By irradiating the insulating film 2 with an electron beam while performing heat treatment on the insulating film 2, the deteriorated layer 2 is partially formed in the thickness direction of the insulating film 2.
b) and insulating film 2 on which altered layer 2b is formed
Forming the wiring recess 5 by selectively etching the insulating film 2 and the altered layer 2b along the film thickness direction of FIG.

In the present embodiment, FIGS.
As shown in (c), for example, a first polymethylsiloxane film 2c is formed in advance as a base insulating film serving as a first interlayer insulating film on the surface as one end surface of the semiconductor substrate 3 having a diameter of 8 inches. Shall be At the same time, it is assumed that a buried interconnect 6 mainly containing copper (Cu) is formed in advance in the first polymethylsiloxane film 2c. The first polymethylsiloxane film (first low-dielectric-constant interlayer insulating film) 2c can be formed by a method of manufacturing a semiconductor device according to the present invention described later, similarly to a second interlayer insulating film 2 described later. That is, the feature of the method of manufacturing the semiconductor device according to the present embodiment according to the present invention is that, in more detail, the base insulating film 2 c as the first interlayer insulating film is formed on the semiconductor substrate 3, The method includes the step of forming the insulating film 2 on the insulating film 2c. However, such a method of manufacturing a semiconductor device according to the present embodiment falls within the category of the method of manufacturing a semiconductor device according to the present invention. It is.

Further, as described above, the first polymethylsiloxane film 2c can be formed by the method of manufacturing a semiconductor device according to the present invention described later, similarly to the second interlayer insulating film 2 described later. Therefore, in this embodiment,
In order to avoid overlapping description of the respective steps of forming the first and second insulating films 2c, 2 in detail, a detailed description is given of the step of forming the first polymethylsiloxane film 2c on the semiconductor substrate 3. The description is omitted, and the step of forming the second interlayer insulating film 2 on the first polymethylsiloxane film 2c will be described in detail.

In this embodiment, a second interlayer insulating film 2 as an insulating film having a thickness of about 1 μm is formed on the first polymethylsiloxane film 2c. On this second interlayer insulating film, a polymethylsiloxane film 2 is formed as a low dielectric constant type interlayer insulating film.

Hereinafter, the step of forming the second polymethylsiloxane film 2 will be described in detail by subdividing it into first to fourth steps.

First step: A film material of the second polymethylsiloxane film 2 as a second low dielectric constant interlayer insulating film, or a low molecular component (precursor) which is a substance constituting the second polymethylsiloxane film 2 Liquid raw material 2 called varnish obtained by dissolving polymethylsiloxane as a solvent in
As shown in FIG. 1A, it is disposed on a first polymethylsiloxane film 2c provided on a semiconductor substrate 3. As a method of arranging the varnish 2, in the present embodiment, the varnish 2 can be uniformly provided with a substantially uniform thickness so that the second polymethylsiloxane film 2 of good quality and uniformity is formed. An application method is adopted. Specifically, the coating operation of the varnish 2 is performed by applying a varnish 2 on the surface of the first polymethylsiloxane film 2c by a spin coat method, which is a type of coating method, using, for example, a coater (not shown) as a coating device. Is what you do.

Second step: first polymethylsiloxane film 2
c is coated with a varnish 2 on the semiconductor substrate 3 as shown in FIG.
As shown in (b), the varnish 2 is placed on a heating device (hot plate) 4 as a temperature control device with the surface side coated with the varnish facing upward. Then varnish 2
Hot plate 4 so that the temperature of
Of the varnish 2 and the semiconductor substrate 3 and the first
The entire polymethylsiloxane film 2c is heated, and this state is maintained for about one minute. Thereby, the varnish 2 is subjected to the first heat treatment.

Third step: Subsequently, the hot plate is maintained such that the temperature of the varnish 2 is maintained at about 200 ° C. while the semiconductor substrate 3 and the first polymethylsiloxane film 2 c are placed on the hot plate 4. 4, the varnish 2 is heated together with the semiconductor substrate 3 and the first polymethylsiloxane film 2c, and this state is maintained for about one minute. Thereby, the varnish 2 is subjected to the second heat treatment.

By the heat treatment in each of the second and third steps, the varnish 2 which is a liquid material of the second polymethylsiloxane film 2 applied on the surface of the first polymethylsiloxane film 2c in the first step is formed. The contained solvent is volatilized (evaporated) and removed. Thus, the varnish (coating film) 2 containing polymethylsiloxane as a main component is fixed (fixed) on the surface of the first polymethylsiloxane film 2c.

According to an experiment conducted by the inventors of the method of manufacturing a semiconductor device according to the present invention, in the heat treatment in the second and third steps, the temperature of the varnish 2 was first set to about 80.degree. The step is performed by heating for about 1 minute step by step, and the components other than polymethylsiloxane, which is a main component of the second polymethylsiloxane film 2, such as the solvent in the varnish 2, are efficiently and almost completely volatilized ( It has been found that this is the preferred (suitable) temperature setting to "fly".

Fourth Step: Subsequently, the semiconductor substrate 3 on which the varnish 2 containing polymethylsiloxane as a main component is fixed and the first polymethylsiloxane film 2c are kept on a hot plate 4 The varnish 2 and the second polymethylsiloxane film 2 formed based on the varnish 2 are placed in a reduced-pressure atmosphere reduced to about 0.1 Torr so as not to be oxidized. At this time, the semiconductor substrate 3 on which the varnish 2 of the second polymethylsiloxane is fixed
The atmosphere in which the first polymethylsiloxane film 2c is disposed is filled with a gas containing nitrogen (N ₂ ) gas as a main component.

In this state, the temperature of the varnish 2 is about 4
The varnish 2 is heated together with the semiconductor substrate 3 by adjusting the temperature of the hot plate 4 so as to be kept at 00 ° C., and as shown by a white arrow in FIG. The varnish 2 is irradiated (exposed) with an electron beam (EB) having an irradiation (acceleration) energy of about 6 keV and an irradiation amount (dose amount) of about 500 μC / cm ² . Thus, a desired second polymethylsiloxane film 2 is formed on the surface of the semiconductor substrate 3.

As described above, the varnish 2 is irradiated with the electron beam while the varnish 2 is subjected to the heat treatment only in the fourth step which is the final step among the second to fourth steps. . By irradiating the varnish 2 in an unfixed state with an electron beam, a component other than polymethylsiloxane such as a solvent contained in the varnish 2 is changed to a low dielectric constant having undesired characteristics. This is to prevent an interlayer insulating film from being formed. That is, this is because an unnecessary component such as a solvent contained in the varnish 2 is skipped and the fixed second polymethylsiloxane film 2 is denatured to obtain a low dielectric constant interlayer insulating film having desired characteristics. .

The second polymethylsiloxane film 2 formed through the above-described first to fourth steps is the same as that shown in FIG.
As shown in FIG. 7, the layer is formed in a state of being separated into three layers having different internal characteristics along the film thickness direction. More specifically, in the fourth step, when the varnish 2 is subjected to the heat treatment, the electron beam irradiated together with the heat treatment has energy characteristics as shown in the graph of FIG.
When an electron beam having such characteristics is irradiated from the surface side of the second polymethylsiloxane film 2 being formed by the heat treatment in the fourth step, most of the energy is applied to the second polymethylsiloxane film. 2 is absorbed in the middle part in the film thickness direction. Although the raw material of the second polymethylsiloxane film 2 is a varnish 2 having a single property, the material in the thickness direction of the second polymethylsiloxane film 2 that has absorbed most of the energy of the electron beam. The portion is formed so as to be altered so as to have different properties from both ends in the film thickness direction which hardly absorbed the energy of the electron beam.

Specifically, the altered layer (altered portion) 2b as an intermediate portion (intermediate layer) in the thickness direction of the second polymethylsiloxane film 2 altered by the electron beam is hardly altered by the electron beam. Second polymethylsiloxane film 2
The etching rate (etching rate) in the etching step (processing) of the second polymethylsiloxane film 2 described later is more than the non-altered layer (non-altered portion) 2a as both ends (upper and lower layers) in the film thickness direction. ) Slow (low)
It is formed so that it becomes.

Next, as described above, the altered layer 2 having a different property (rate to be etched) is provided in the middle portion in the thickness direction.
For the second polymethylsiloxane film 2 having a thickness of about 1 μm and having a thickness of about 1 μm, the Cu embedded wiring 6 previously formed in the first polymethylsiloxane film 2c is
Wiring recess 5 for connecting upper and lower wiring (not shown)
Is formed at a plurality of locations by etching. In the present embodiment, the surface of the second polymethylsiloxane film 2 is
While covering with a mask (not shown) on which a desired wiring pattern is formed, a CF-based gas, which is an etching gas (not shown), is blown from the surface side to form a wiring recess having a diameter of about 0.175 μm. Wiring grooves (holes) 5 are formed at a plurality of locations on the second polymethylsiloxane film 2. At this time, each wiring groove 5 is set so that the deepest part (bottom part) penetrates the upper part in the thickness direction of the polymethylsiloxane film 2 to reach the middle part, or penetrates the middle part.

After the etching step is completed, the shape and the like of each formed wiring groove 5 are examined. Among the differences (variations), the difference in the depth of each wiring groove 5 which is the main one is as follows. It was only about 5% at the central part (center part) and the peripheral part (edge part) of the 8-inch semiconductor substrate 3. More specifically, in each wiring groove 5 formed in the second polymethylsiloxane film 2 formed by the manufacturing method of the present embodiment, the wiring groove 5 is formed on the periphery of the 8-inch semiconductor substrate 3 and the first polymethylsiloxane film 2c. The wiring groove 5b formed at the position facing the wiring groove is only about 5% deeper than the wiring groove 5a formed at the position facing the center of the semiconductor substrate 3. That is, in the second polymethylsiloxane film 2, each of the wiring grooves 5a and 5b formed therein is formed.
Regardless of the position where those etching processes were performed,
Compared with the above-described conventional technology, the variation in the depth was reduced to about half. That is, in the second polymethylsiloxane film 2, almost no variation in depth was observed between the wiring grooves 5a and 5b formed by etching. An error of about 5% in the processing dimension in the etching process is caused by providing the second polymethylsiloxane film 2 as a low dielectric constant interlayer insulating film and providing a wiring (not shown) provided in the second polymethylsiloxane film 2. The performance of the semiconductor device 1
It is within an allowable error range that can be neglected to maintain a practically appropriate level.

As described above, the etching rate of the second polymethylsiloxane film 2 formed by the manufacturing method of the present embodiment at the position opposed to the peripheral portion of the semiconductor substrate 3 is set at the central portion of the semiconductor substrate 3. It was only about 5% faster than the etched rate at the opposing position. This is because, as described above, in the altered layer 2b formed in the middle part of the second polymethylsiloxane film 2 in the thickness direction, the etching rate along the thickness direction of the second polymethylsiloxane film 2 is reduced. This is considered to be because the difference, that is, the variation in the etching rate was adjusted (corrected) so as to be substantially uniform.

According to an experiment conducted by the inventors of the method of manufacturing a semiconductor device according to the present invention, the polymethylsiloxane film 102 formed by the above-described conventional method of forming an insulating film is exposed to CF-based gas. The etching rate was about 300 nm / min. On the other hand, in the method of manufacturing a semiconductor device according to the present embodiment according to the present invention, an electron beam having an irradiation energy of about 6 keV and an irradiation amount (dose amount) of about 500 μC / cm ² is irradiated with an electron beam having a thickness of about 1 μm. The rate of etching of the deteriorated layer 2b of the second polymethylsiloxane film 2 with respect to the CF-based gas formed by irradiating the second polymethylsiloxane film 2 was about 100 nm / min. Further, as described above, the etching rate of the non-altered layer 2a of the second polymethylsiloxane film 2 to which the electron beam is hardly absorbed by the CF-based gas is determined by the conventional semiconductor device manufacturing method. The etching rate of the second polymethylsiloxane film 2 with respect to the CF-based gas was about 300 nm / min.

That is, the second polymethylsiloxane film 2 having a thickness of about 1 μm formed by the method for manufacturing a semiconductor device of the present embodiment has a depth (height) at an intermediate portion along the thickness direction. Or it may be called thickness.)
In the vicinity of about 500 nm, an altered layer 2b (altered area, altered film) having an etching rate of about 100 nm / min is formed, and at both ends having other depths,
An unaltered layer 2a (unaltered region, unaltered film) having an etching rate of 300 nm / min is formed. Therefore, the second polymethylsiloxane film 2 of the present embodiment
At a position facing each of the central part and the peripheral part of the semiconductor substrate 3 and the first polymethylsiloxane film 2c, a relatively high speed of about 300 nm / min forming the upper part of the second polymethylsiloxane film 2 is obtained. The difference (variation) in the etching rate generated in the non-degraded layer 2a having a high etching rate (high etching rate portion) is about 100 nm / min which forms the intermediate portion of the second polymethylsiloxane film 2. Of the deteriorated layer 2b having a relatively slow etching rate (low etching rate portion), the difference (variation) in the depth of each of the wiring grooves 5a and 5b finally formed is reduced. You can see that.

According to an experiment conducted by the inventors of the method of manufacturing a semiconductor device according to the present invention, the insulating film 2 other than the second polymethylsiloxane film 2 used in the present embodiment was It has been found that by performing the heating operation and the electron beam irradiation operation together in the forming process, a part of the heating process and the electron beam irradiating process can be performed in a modified manner. Furthermore, by performing the heating operation and the electron beam irradiation operation together, it is possible to perform a cross-linking reaction between molecules, a breaking of a molecular chain, or a separation of various groups, which cannot be realized by mere heat treatment, It has been found that an insulating film 2 having a structure different from that of firing the insulating film only by the heat treatment can be obtained. For example, when an organic silicon oxide film, which is a type of a low dielectric constant film (not shown), is formed by performing both a heating operation and an electron beam irradiation operation, the bond between the CH ₃ group and the main chain is cut by electron beam irradiation. Then, while maintaining a low dielectric constant, structurally SiO ₂
It has been revealed by the present inventors that a film close to a film can be formed.

As described above, according to the method of manufacturing a semiconductor device according to the present invention, the non-uniformity of the etching reaction rate inside the second insulating film 2 formed on the surface of the first polymethylsiloxane film 2c. In order to solve the problem, for example, a portion having a different etching rate is formed in the middle of the second insulating film 2 as a film to be processed, and the processing dimension of the wiring concave portion 5 and the like resulting from the non-uniformity of the etching rate there. An etching technique (insulating film forming technique), which has been eagerly demanded in recent years, in which the variation is suppressed and adjusted, can be easily implemented.

According to an experiment conducted by the inventors of the method of manufacturing a semiconductor device according to the present invention, when the varnish 2 is irradiated with an electron beam in the fourth step, the temperature of the varnish 2 is set at 20 degrees.
0 ° C or more and less than 500 ° C, preferably about 380 ° C to 400 ° C
The semiconductor device 1 including the second polymethylsiloxane film 2 formed by the present manufacturing method can perform a practically appropriate operation performance by performing a heat treatment so that the temperature becomes substantially constant within the range of about ° C. It has been clarified that a high quality second polymethylsiloxane film 2 that can be exhibited can be formed. In particular, the set temperature of the varnish 2 of about 400 ° C. is in the temperature range of about 380 ° C. to 400 ° C., and the semiconductor device 1 including the second polymethylsiloxane film 2 formed by the present manufacturing method is practically used. This is a value at which an extremely high quality second polymethylsiloxane film 2 capable of exhibiting extremely good operation performance can be formed.

According to an experiment conducted by the inventors of the method of manufacturing a semiconductor device according to the present invention, the irradiation amount of the electron beam applied to the varnish 2 in the fourth step is approximately 500 μC / cm ² or more. By performing electron beam irradiation while setting the value to be a constant value, the semiconductor device 1 including the second polymethylsiloxane film 2 formed by the present manufacturing method can exhibit high quality that can exhibit practically appropriate operation performance. It has been clarified that a suitable second polymethylsiloxane film 2 can be formed. In particular, the set irradiation dose of the electron beam of about 500 μC / cm ² is:
Even within the range of the irradiation amount of about 500 μC / cm ² or more, the semiconductor device 1 including the second polymethylsiloxane film 2 formed by the present manufacturing method can exhibit extremely good operation performance in practical use. This is a value at which the second polymethylsiloxane film 2 can be formed.

Similarly, according to an experiment conducted by the inventors of the method of manufacturing a semiconductor device according to the present invention, the acceleration energy of the electron beam applied to the varnish 2 in the fourth step is increased by several keV.
By irradiating the electron beam while setting it to be a substantially constant value within a range of about 15 keV, the semiconductor device 1 having the second polymethylsiloxane film 2 formed by the present manufacturing method can be practically used. It has been clarified that a high-quality second polymethylsiloxane film 2 capable of exhibiting appropriate operation performance can be formed. In particular, the set energy amount of the electron beam of about 6 keV is within the energy amount range of about several keV to about 15 keV. This is a value at which an extremely high quality second polymethylsiloxane film 2 capable of exhibiting extremely good operation performance can be formed.

Further, according to an experiment conducted by the inventors of the method of manufacturing a semiconductor device according to the present invention, when the varnish 2 is irradiated with an electron beam while being subjected to heat treatment in the fourth step,
By disposing the varnish 2 in a predetermined gas under a reduced pressure atmosphere within a predetermined range, the semiconductor device 1 including the second polymethylsiloxane film 2 formed by the present manufacturing method can operate in a practically appropriate manner. It has been clarified that a high-quality second polymethylsiloxane film 2 capable of exhibiting performance can be formed. In particular, in the nitrogen gas,
By arranging the varnish 2 in an atmosphere set at a substantially constant reduced pressure value of about 0.1 Torr, the semiconductor device 1 having the second polymethylsiloxane film 2 formed by the present manufacturing method is extremely excellent in practical use. It has been clarified that an extremely high quality second polymethylsiloxane film 2 capable of exhibiting operation performance can be formed.

As described above, according to the method of manufacturing a semiconductor device of this embodiment, in the step of forming the second polymethylsiloxane film 2, the heat treatment and the electron beam irradiation treatment are used in combination. The intermediate portion of the polymethylsiloxane film 2 in the thickness direction is more etched than both ends.
The deteriorated layer 2b having a low rate can be easily formed. As a result, of the two polymethylsiloxane films 2 in the thickness direction, the difference in the etching rate caused by the difference in the etching position in the upper layer on the side where the etching is started can be easily reduced in the middle portion. Can be reduced to Consequently, each wiring groove 5a,
The difference in depth between 5b can be easily reduced. That is, according to the method for manufacturing a semiconductor device of the present embodiment, the processing accuracy of the second polymethylsiloxane film 2 by etching can be easily improved. Therefore, according to the method for manufacturing a semiconductor device of the present embodiment, the electrical performance (quality) of the second polymethylsiloxane film 2 formed by this manufacturing method can be easily improved.

Further, according to the semiconductor device 1 having the second polymethylsiloxane film 2 formed by the method of manufacturing a semiconductor device of the present embodiment, the processing accuracy of the second polymethylsiloxane film 2 by etching is high. In addition, the electrical performance of the second polymethylsiloxane film 2 can be easily improved, and the yield of the semiconductor device 1 can be easily improved. Further, since the electrical performance of the second polymethylsiloxane film 2 can be easily improved, the electrical performance of the entire semiconductor device 1 can be easily improved. Therefore, according to the semiconductor device 1 including the second polymethylsiloxane film 2 formed by the method for manufacturing a semiconductor device according to the present embodiment, the yield can be improved, the production efficiency can be improved, and the semiconductor having a high processing capability can be obtained. The apparatus 1, and thus various semiconductor devices having a high processing ability using the semiconductor apparatus 1, can be produced.

The operations and effects described above are:
Needless to say, the first polymethylsiloxane film 2c as the first low dielectric constant interlayer insulating film can be similarly obtained. That is, the semiconductor device 1 manufactured by the method for manufacturing a semiconductor device according to the present invention includes the
The entire first polymethylsiloxane film 2c and second polymethylsiloxane film 2 having a layered structure have sufficient strength for practical use, and a substantially uniform high-quality first polymer that does not hinder the performance of the semiconductor device 1. It is formed as a methylsiloxane film 2c and a second polymethylsiloxane film 2.

The method for manufacturing a semiconductor device according to the present invention and the semiconductor device 1 manufactured by this method are not limited to the above-described embodiment. Each step of the method for manufacturing a semiconductor device according to the present invention can be set in various states without departing from the gist of the present invention.

For example, the method of manufacturing a semiconductor device according to the present invention is applicable not only to the case of forming the above-described two-layer insulating films 2c and 2 but also to the case of forming an insulating film having a multilayer structure of three or more layers. Alternatively, even when only one insulating film is formed, the same effect as when the insulating films 2c and 2 having the two-layer structure are formed can be obtained. Further, the insulating film formed by the method of manufacturing a semiconductor device according to the present invention,
A film other than the above-described polymethylsiloxane film, which is a low dielectric constant film, may be used. Any material can be used as long as it can be modified so that the etching rate of a desired portion of the insulating film can be set to a desired speed by using at least the heating operation and the electron beam irradiation operation. Further, the method of forming the insulating film does not have to be the coating method described above. Any method other than the above-described coating method may be used as long as the quality of the film to be formed can be maintained in a good state depending on the material of the insulating film.
For example, a higher quality insulating film can be formed by employing the CVD method.

When the insulating film is formed, instead of evaporating the solvent by increasing the temperature stepwise, the varnish is placed under a predetermined reduced pressure atmosphere to evaporate the solvent.
The insulating film may be fixed to the substrate. Further, the position at which the altered layer is formed depends on the desired depth of the wiring recess.
What is necessary is just to form in the position which can adjust the variation of the processing dimension.

Further, various set values such as the above-mentioned varnish heating temperature and time, electron beam acceleration energy and irradiation amount, and reduced pressure value of the atmosphere are determined by the method of manufacturing a semiconductor device according to the present invention. Various combinations may be set according to the manufacturing environment as long as the performance of the device can reach a desired level.

[0074]

According to the method of manufacturing a semiconductor device of the present invention, the wiring recess is etched from the insulating film toward the semiconductor substrate, and when the bottom reaches the deteriorated layer, the wiring recess is formed. It is easy to almost eliminate the difference in the formation rate (working rate) of the wiring recess due to the difference in the etching rate (etching rate) in the non-degraded portion of the insulating film depending on the position. Can be trimmed. Therefore, regardless of the formation position of the wiring concave portion,
Since the processing speed of the wiring recess by etching can be easily set so as to be substantially uniform, the processing accuracy of the wiring recess by etching and, consequently, the processing accuracy of the insulating film can be easily improved.

Further, in carrying out the method of manufacturing a semiconductor device according to the present invention, the semiconductor device may be suitably formed according to the desired formation position and size of the wiring recess or the desired performance of the insulating film. By setting the formation environment of the affected layer, the material for forming the insulating film, and the like, the formation speed (working speed) of the wiring concave portion can be set to an appropriate state. Therefore, regardless of the position where the wiring concave portion is formed, the processing accuracy of the wiring concave portion by etching and the processing accuracy of the insulating film can be more easily improved.

According to the semiconductor device of the present invention,
The wiring recesses are etched from the insulating film toward the semiconductor substrate, and when the bottom reaches the deteriorated layer, the etching rate (etching / etching rate) in the non-transformed portion of the insulating film depends on the position where the recess is formed. The formation rate is easily adjusted so that the difference in the forming speed (working speed) due to the difference in the rate can be almost eliminated. Therefore, regardless of the formation position of the wiring concave portion, the processing speed of the wiring concave portion by etching is easily set so as to be substantially uniform, so that the processing accuracy of the wiring concave portion by etching and, consequently, of the insulating film. Processing accuracy is easily improved.

Further, in implementing the semiconductor device according to the present invention, the desired formation position and size of the wiring concave portion,
Alternatively, in accordance with the desired performance of the insulating film, etc., the formation environment of the deteriorated layer, the material for forming the insulating film, and the like are set so as to be suitable for them, and the forming speed (working speed) of the wiring concave portion is appropriate. Is set to an appropriate state. Therefore, the processing accuracy of the wiring concave portion by etching and the processing accuracy of the insulating film can be easily improved regardless of the position where the wiring concave portion is formed.

[Brief description of the drawings]

FIG. 1 is a process sectional view schematically illustrating a method for manufacturing a semiconductor device according to a first embodiment of the present invention, in which (a) shows a semiconductor substrate and a second polymethylsiloxane film on a second polymethylsiloxane film; FIG. 1B shows a state in which a siloxane film is formed.
FIG. 1A shows a state in which the second polymethylsiloxane film is irradiated with an electron beam while being subjected to a heat treatment, and FIG. 1C shows a wiring groove formed by etching in the second polymethylsiloxane film in FIG. The respective states are shown.

FIG. 2 is a graph showing the film thickness dependence of the amount of energy absorbed by a second polymethylsiloxane film of the electron beam shown in FIG. 1 (b).

FIGS. 3A and 3B are process cross-sectional views schematically showing a method for manufacturing a semiconductor device according to a conventional technique, wherein FIG. 3A shows a state in which a polymethylsiloxane film is formed on a semiconductor substrate, and FIG.
1A shows a state in which a heat treatment is applied to the polymethylsiloxane film, and FIG. 1C shows a state in which a wiring groove is formed in the polymethylsiloxane film in FIG. 1A by etching.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Semiconductor device 2 ... 2nd polymethyl siloxane film (2nd low dielectric constant interlayer insulating film, varnish) 2a ... Insulating film non-altered layer (Insulating film upper and lower layers, high etching rate part) 2b ... Insulating film altered layer (Insulating film intermediate layer, low etching rate portion) 2c: first polymethylsiloxane film (first low dielectric constant interlayer insulating film, base insulating film, varnish) 3: semiconductor substrate 4: hot plate (temperature control device) 5 ... wiring groove (recess for wiring) 5a ... central wiring groove 5b ... peripheral wiring groove 6 ... Cu embedded wiring

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 21/88 M 21/90 SV (72) Inventor Rinpei Nakata 8 Shinsugita-cho, Isogo-ku, Yokohama-shi, Kanagawa Prefecture Address F-term in Toshiba Yokohama Office (reference) 5F033 HH11 MM01 QQ09 QQ11 QQ35 QQ54 QQ74 RR21 SS22 WW00 WW03 XX00 XX03 XX24 XX25 5F058 AC03 AF04 AG02 AG10 AH02

Claims (17)

[Claims] A step of forming an insulating film on a semiconductor substrate; and irradiating the insulating film with an electron beam while performing a heat treatment on the insulating film, so that the insulating film has a thickness direction. Forming a depressed layer for wiring by selectively etching the insulating film and the degraded layer along a thickness direction of the insulating film on which the degenerated layer is formed; A method for manufacturing a semiconductor device, comprising: 2. A method according to claim 1, wherein a portion of the insulating film in a film thickness direction is altered so that an etching rate of the altered layer formed on the insulating film is lower than an etching rate of the insulating film. The method of manufacturing a semiconductor device according to claim 1. 3. The method for manufacturing a semiconductor device according to claim 1, wherein the altered layer of the insulating film is formed at an intermediate portion in the thickness direction of the insulating film. 4. The method of manufacturing a semiconductor device according to claim 1, wherein said insulating film is formed using an insulating film having a low dielectric constant. 5. The method according to claim 4, wherein the low dielectric constant film is formed using polymethylsiloxane. 6. The method of manufacturing a semiconductor device according to claim 1, wherein said insulating film is formed by a coating method. 7. A method of applying the material of the insulating film on the semiconductor substrate, heating the material of the insulating film so as to increase its temperature stepwise, and fixing the material on the semiconductor substrate. After forming the insulating film on the semiconductor substrate, by irradiating the electron beam toward the insulating film while heating the insulating film so that the temperature is maintained at a higher temperature 7. The method for manufacturing a semiconductor device according to claim 1, wherein an altered layer is formed in a part of the insulating film in a thickness direction. 8. The method according to claim 1, wherein, when irradiating the electron beam, a heat treatment is performed so that the temperature of the insulating film is not lower than 200 ° C. and lower than 500 ° C. 13. The method for manufacturing a semiconductor device according to item 10. 9. The semiconductor according to claim 1, wherein the irradiation amount of the electron beam is set to 500 μC / cm ² or more when irradiating the electron beam. Device manufacturing method. 10. The semiconductor device according to claim 1, wherein said insulating film is arranged under a predetermined reduced pressure atmosphere when irradiating said electron beam. Method. 11. The semiconductor device according to claim 1, wherein a buried wiring mainly composed of copper is formed in said low dielectric constant insulating film. Production method. 12. A semiconductor device comprising: a semiconductor substrate; an insulating film formed on the semiconductor substrate; and a wiring recess formed in the insulating film. A semiconductor device, wherein an altered layer is formed in a part of a thickness direction by heat treatment and irradiation with an electron beam. 13. The semiconductor device according to claim 12, wherein said insulating film is formed such that an etching rate of said altered layer is lower than an etching rate of said insulating film. 14. The semiconductor device according to claim 12, wherein the altered layer of the insulating film is formed at an intermediate portion in the thickness direction of the insulating film. 15. The semiconductor device according to claim 12, wherein said insulating film is formed using a low dielectric constant insulating film. 16. The semiconductor device according to claim 15, wherein said low dielectric constant insulating film is composed mainly of polymethylsiloxane. 17. The semiconductor device according to claim 10, wherein a buried wiring containing copper as a main component is formed in said low dielectric constant insulating film.