JPH01303432A - Photosensitive resin composition - Google Patents

Abstract

PURPOSE:To provide excellent film quality, processing accuracy and definition by incorporating polysiloxane having a radical polymerizable substituent and polysilane into the above compsn. CONSTITUTION:This compsn. contains the polysiloxane having the radical polymerizable substituent and the polysilane. The polysilane having a high silicon content is incorporated as a photosensitive agent therein and since the polysilane self has excellent O2-RIE resistance, the degradation in the O2-RIE resistance possessed by the polysiloxane is obviated. Both the polysiloxane and the polysilane have relatively analogous solubility in arom. solvents and ether solvents and, therefore, the compatibility is high and the phase sepn. arises hardly. The sensitivity is improved in this way and the film having uniform quality is obtainable. The formation of a good resist pattern is thus possible.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) This invention relates to the manufacture of semiconductor devices, particularly active elements thereof,
The present invention relates to a photosensitive resin composition suitable as a resist material used for producing wiring patterns and the like.

(Conventional technology) In the manufacturing of semiconductor devices, what about semiconductor substrates? ! Various processing is performed. Among these, microfabrication using resist patterns is one of the most important, and is essential for forming active elements, wiring patterns, etc. of semiconductor devices. An example of this processing is shown below.

FIGS. 1A to 1D are diagrams schematically showing an example of the process of forming a metal wiring pattern in the manufacturing process of a semiconductor device using a cross-sectional view of a substrate.

A wiring metal film 13 is formed on the entire surface of the processed substrate 11, and a resist film 15 is formed on the wiring metal film 13 (FIG. 1(A)). Next, predetermined treatments such as exposure and development are performed on this resist film 15 to form a resist pattern 15a (see Fig. 1 (B).
)) Then, using this resist pattern 15a' as a Fr mask, the wiring metal 13 is etched (see FIG.
C)). After that, the resist pattern 15a is removed, and 1
A desired metal wiring pattern 3a is obtained (FIG. 1(D)).

By the way, in recent years, semiconductor devices, especially ICs (integrated circuits), have adopted multilayer wiring in order to achieve higher integration and higher speed.
Wiring patterns are becoming finer. This trend is expected to further advance in the future, and as a result, even finer resist patterns will be required for the manufacture of ICs. However, on the other hand, in order to prevent an increase in wiring resistance due to miniaturization, the aspect ratio of wiring patterns tends to be high, that is, the thickness of the gold 4 film is increased, and as a result, this type of wiring pattern is not stacked. In a board having multilayer wiring, the height difference on the board becomes larger and larger.

For this reason, when a fine resist pattern is formed on a substrate having such a step difference, the following problems occur, for example. That is, it becomes difficult to accurately form a resist pattern of a desired size within the allowable depth of focus using a reduction projection exposure system, regardless of the presence of steps.

Particularly when trying to obtain a resist pattern of submicron rule, a reduction projection exposure bag equipped with a lens with a large numerical aperture is advantageous and used, but the depth of focus in such an apparatus becomes increasingly shallow. Therefore, it becomes difficult to focus on both the concave and convex portions, and it may become impossible to form a resist pattern using only one layer of resist as in the past. A two-layer resist method was used to solve this problem.

Figure 2 (△) to (F) show the process percentages of this two-layer resist method.
FIG. 2 is a perspective view of a portion of an IC, showing a case where a second layer of metal wiring is formed on the first layer of metal wiring with an insulating film interposed therebetween. A first layer of metal wiring, denoted by 23, is formed on the substrate denoted by 2+, and a second layer of metal wiring, denoted by 27, is formed on the -th interlayer line 23 via an insulating film, denoted by 25. A thin film of (Fig. 2) is formed.
A)). As a result, the first layer metal wiring 23 and the substrate 21
A step 29 is formed between the two. Therefore, in the two-layer resist process, first, a thick film of thermosetting resin 31 is formed on the substrate 21 having the step 29 to planarize the base (Fig. 2 (8)), and then this On the thermosetting resin 31, a photosensitive resin 33 showing high resistance to oxygen plasma is formed in an extremely thin film thickness (FIG. 2 (C:)). Next, this photosensitive resin 33
A photosensitive resin pattern shown as 33a is obtained by subjecting it to predetermined treatments such as exposure and development (FIG. 2(D)), and then
Using this photosensitive resin pattern 33a as a mask, the thermosetting resin 31 is etched by ion etching (0
□-RIE) to obtain a two-layer resist pattern with a high aspect ratio of 35 (see Figure 2 (E)).
)). Thereafter, the composite thin film 27 is etched using the two-layer resist pattern 35 as a mask to obtain a second layer of metal wiring 27a (FIG. 2(F)). The advantage of this two-layer resist method is that the base is flattened with the layer 31 and the pattern of the extremely thin photosensitive resin layer 33 is formed on this layer 31, so it is not affected by the level difference in the base. It is possible to form a fine pattern with a high aspect ratio and no fluctuation. As the resist used as the photosensitive resin layer 33, there is a resist containing silicon, for example, as disclosed in Japanese Patent Laid-Open No. 62-2843 filed by the present applicant.
There is a negative resist disclosed in Publication No. 2. This negative resist is made of polyallylsilsesquioxane,
It is a mixture of bisazide compounds such as 2,6-bis(4'-azidobenzylidene)-4-methylcyclohexanone, and has a sensitivity of I ImJ/cm2 to far ultraviolet rays and a resolution of 0.5 um. .

(Problems to be Solved by the Invention) However, if the resist disclosed in JP-A No. 62-28432 is left to stand after forming a film, a phenomenon occurs in which his azide precipitates.

That is, there was a problem in that the compatibility between polyallylsilsesquioxane and hiscyazide was low. A coating film formed when bisazide is precipitated is not desirable for forming a resist pattern, so improvements are desired.

In addition, since bisazide is added, the inherent 02-RIE resistance of polysilsesquioxane is reduced.
The initial etching amount reaches 15um.

Therefore, there is a problem in that the difference in dimensional conversion during etching becomes large depending on the etching conditions.

This invention has been made in view of these points, and therefore, the purpose of this invention is to solve the above-mentioned problems and provide a photosensitive resin composition that exhibits excellent film quality, processing accuracy, and resolution. There is a particular thing.

(Means for Solving the Problems) In order to achieve this object, the photosensitive resin composition of the present invention is characterized by containing a polysiloxane having a radically polymerizable substituent and a polysilane.

Here, the polysiloxane may be monolayered, but for example, polysilsesquioxane with a high silicon content is preferred. It can also be a linear polysiloxane. Further, the polymerizable group contained in the polysiloxane may in principle be of any type as long as it is radically polymerizable, but preferable are allyl groups, vinyl groups, etc., which are highly radically polymerizable. Taking this into consideration, for example, polyallylsilsesquioxane represented by formula (I) below can be said to be a suitable polysiloxane. This resin (polyallysilsesquioxane) can be obtained with good controllability depending on the polymerization conditions to have an average weight molecular weight Mw of 2,000 to 100,000. This resin can be obtained, for example, by condensing and polymerizing an oligomer obtained by hydrolyzing allyltrichlorosilane or allyltrialkoxy with a tertiary amine such as triethylamine or tri-n-butylamine.

Further, the polysilane used as a photosensitizer may be either one that causes a decrease in molecular weight or one that causes an increase in molecular weight upon irradiation with ultraviolet rays. This is because, in any reaction in which the molecular weight decreases or increases, the silyl radical generated by cleavage of 5i-3i by ultraviolet irradiation, or silylene, which is electronically similar to carbene, or the radically polymerizable substituent of polysiloxane ( For example, the allyl group of polyallylsilsesquioxane)
This is because it utilizes radical addition to . Therefore, any polysilane can be used as long as it is soluble in organic solvents. Examples of such polysilanes include the following.

Hexaphenyldisilane represented by the following formula (II),
Disilane such as tetraphenyldimethyldisilane represented by the following formula (■), tetramethyldiphenyldisilane represented by the following formula (IV), hexamethyldisilane represented by the following formula (V), etc.

Cs H5C6H5 Ce Hs Ct; Hs l CH3Ct-+3 l CH3CH3 The following (obtained by coupling with Na (sodium))
A polysilane as shown in the formula V[).

A polysilane such as polysilastyrene represented by the following formula (■) obtained by coupling dimethyldichlorosilaf and phenylmethyldichlorosilane with tNa.

1. Polydisilanylene phenylenes as shown by the following formula (■) obtained by cross-coupling 4-his(dimethylurorosilyl)benzene.

Cyclopolysilanes as silylene generators such as octamethylcyclotetrasilane represented by (IX) below, todecamethylcyclohexasilane represented by (X) below, and the like.

CH30H3 Among the above-mentioned various polysilanes, those with a high radical or silylene generation efficiency are advantageous because they can strongly improve resist sensitivity, so in the formula (Vl) and (Vfll), Linear polysilanes as shown below and cyclic polysilanes as shown in formulas (IX) and (X) can be mentioned.

In addition, in the rush of the present invention, it is preferable that the content of polysilane to polysiloxane is 5 to 50% by weight. The reason for this is that if the content is less than 5%, the desired sensitivity cannot be obtained, and if it is more than 50%, there will be problems with adhesion etc. when used as a resist film.

In general, for the implementation of this invention, the above-mentioned polysilsesquioxane has a weight average molecular weight Mw of 2000 to 1000.
00 is preferable.

(Function) According to the photosensitive resin composition of the present invention, polysilane with a high silicon content is contained as a photosensitizer, and this itself has excellent 02-RIε resistance, so polysiloxane has 02-RIE resistance. There is no reduction in performance.

Furthermore, since both polysiloxane and polysilane have relatively similar solubility in, for example, aromatic solvents and ether solvents, their compatibility is high and phase separation is less likely to occur.

Further, as is clear from the experimental results described later, the sensitivity of the photosensitive resin can be controlled by both the molecular weight of the polysiloxane and the content ratio of polysilane to polysiloxane. Here, even if the sensitivity is improved by increasing the content of polysilane, phase separation will not occur because of the high compatibility for the above-mentioned reasons.

(Examples) Examples of the photosensitive resin composition of the present invention will be described below. However, it should be understood that the numerical conditions, equipment used, chemical names, etc. described in the following examples are merely illustrative, and the present invention is not limited to these conditions only.

East JL Example - <Compatibility Evaluation> First, the compatibility between polysiloxane and polysilane was evaluated by the method described below.

A polyallyl silsesquioxane represented by the above formula (I) having a weight average molecular weight Mw of 20400 and a specific dispersion of 4.6,
Hexaphenyldisilane represented by the formula (II ''), tetraphenyldimethyldisilane represented by the formula (III), dotecamethylsiurohexasilane represented by the formula (X), as a photosensitizer; IX) Mix octamethylcyclotetrasilane represented by the formula as shown in Attached Table 1, dissolve each mixture in chlorobenzene to make a 10% solution, and perform the experiments shown in sample numbers ■ to ■. A solution of Example was prepared.Meanwhile, polyallylsilsesquioxane similar to that of Example and 2,6-bis(4'-azitohenzylidene)- represented by the following formula (XI) as a photosensitizer were prepared. 4-Methylcyclohexanone in Attached Table 1
Each mixture was mixed as shown in , and each mixture was dissolved in chlorobenzene to prepare solutions of comparative examples shown in sample numbers ① to ②.

Next, each of the solutions indicated by sample numbers ■ to ■ is applied onto individual silicon wafers with a diameter of 2 inches (1 inch is approximately 2.54 cm) to form a film by spin coating, and these wafers are placed on a hot plate. Soft cooling was performed at a temperature of 100° C. for 1 minute. The film on each wafer was then observed with an optical microscope immediately after the hake and after it had been allowed to stand at room temperature for one day. ). The results are shown in Attached Table 1. As can be understood from the results in Attached Table 1, it was confirmed that all the films formed using the solutions of Examples were good films. The reason why the amount of disilane represented by formula (II) added is small is that this compound itself is difficult to dissolve in chlorobenzene.

<02-RIE Resistance Evaluation> Next, the ion etching (0□-RIE) resistance of the photosensitive resin composition of the present invention using reactive oxygen gas was evaluated by the method described below. went.

A solution prepared by dissolving only polyallyl silsesquioxane similar to that used in Example 1 in chlorobenzene, and Example 1
Using the solution of sample number ■ prepared in Example 1 and the solution of sample number [phase] prepared in Example 1 and containing a conventional photosensitizer, a film with a thickness of 0.2 um was deposited on individual silicon wafers. A dry film was formed. Next, the film on each wafer was etched for 20 minutes with 02 gas using a DEM451 parallel plate dry etcher (manufactured by Nikkei Anelva Corporation). The conditions are that the gas pressure is 1, OPa, the gas flow rate is 20 SCCM, and the power density is 0.12 W/cm2.

After the etching and etching were completed, the remaining film thickness of each wafer was measured using a film thickness meter (Talystep (manufactured by Taylor Pobson)) to determine the etched amount.

The results were as shown in the table below. Note that the term Δt in the table is the amount of etched p.

As can be understood from the above results, the film of the example containing dodecamethylhexasilane (X) as a photosensitizer
It was confirmed that the 2-RIE resistance was three times higher than that of the comparative film containing bisazide (XI) V, and was also confirmed to be equivalent to the 02-RIE resistance of the parent material, Siloxashi. Ta.

Evaluation of Resist Sensitivity Next, the sensitivity of the photosensitive resin composition of the present invention was evaluated by the method described below.

(Example 3-(1)) A polyallylsilsesquioxane represented by the formula (I) with a weight average molecular weight Mw of 20400 and a specific dispersion of 4
．． 6, polyarylsilsesquioxane 189, and (
X) Dodecamethylcyclohexasilane 29 represented by the formula
A resist solution was prepared by dissolving a mixture of the above in Urorohensen to form a 10% by weight solution. Next, the above-mentioned resist solution was applied by spin coating onto the photoresist film on the silicon substrate, which had been previously formed to a thickness of 1.5 um, and heated to a temperature of 100°C on a hot plate. Hake for 1 minute with 0
．． A film with a thickness of 2 um was formed. Multiple sample wafers were prepared under similar conditions, and the film on each sample wafer was tested. ! Exposure was performed using photomasks having test patterns with different line widths and changing the exposure J. The exposure bag used was a Canon PLA 501 contact exposure system equipped with an Xe-89 lamp and a CM250 cold mirror. Then, methyl isobutyl ketone (M
After development was performed for 20 seconds using a 1:1 (volume ratio) mixed solution of ISK) and 2-propertool (IPA), rinsing was performed for 15 seconds using 2-propertool. The film thickness of the portion corresponding to the lum line and space of the resist pattern formed on each wafer was measured for each wafer using a Uristep (film thickness meter). As a result, the residual film rate was 5
It was found that the dose ff1D, which becomes 0%, is 240 mJ/cm2 (tare'), and the dose that resolves the line and space of 1 LIm as designed is 440 mJ/cm2.

(Example 3-(2)) The content of the photosensitizer represented by formula (X) with respect to the polyallylsilsesquioxane represented by formula (I) was determined in Example 3-(
Examine the sensitivity when different from 1). In this example, polyallylsilsesquioxane is 169 and (X
) Dodecamethylcyclohexasilane represented by the formula 49
shall be. The sample wafer was prepared, exposed, and developed under the same conditions as in Example 3-(1) except for the above conditions.

As a result, the remaining film rate is 50% at a dose jLD. is 17
It was found that the dose 1 that resolved the lum line and space as designed was 360 mJ/cm2.

(Example 3-(3)) Polyallylsilsesquioxane represented by the formula CI) having a weight average molecular weight Mw of 53000 and a specific dispersion of 5.6 was used as 189, and the polyallylsilsesquioxane represented by the formula (X) was used. 29 dodecamethylcyclohexane is used. The sample wafer was prepared, exposed, and developed under the same conditions as in Example 3-(1) except for the above conditions. As a result, the residual film rate was 50%.
The dose measurement is 80 mJ/cm2, and lum
It was found that the dose for resolving lines and spaces as designed was I 40 mJ/cm2.

(Example 3-(4)) A polyallyl silsesquioxane represented by the formula (1) with a weight average molecular weight Mw of 20400 and a specific dispersion of 4.6 was used as a photosensitizer. III) Tetraphenyldimethyldisilane represented by the formula 49 is used. The sample wafer was prepared, exposed, and developed under the same conditions as in Example 3-(1) except for the above conditions. As a result, the dose measurement that gives a residual film rate of 50%, 1, is 840 m.
J/cm2, and the dose for resolving lum lines and spaces as designed was 900 mJ/cm2.

(Example 3-(5)) A polyallyl silsesquioxane represented by the formula (I) having a weight average molecular weight Mw of 20400 and a specific dispersion of 4.6 was used as a photosensitizer (IX ) Octamethylcyclotetrasilane shown by the formula 29 is used. The sample wafer was prepared, exposed, and developed under the same conditions as in Example 3-(1) except for the above conditions. As a result, the dose measurement results in a residual film rate of 50%. is 260mJ/
cm2, and the dose amount for resolving lum lines and spaces as designed was found to be 440 mJ/am2.

(Example 3-(6)) A polyallyl silsesquioxane represented by the formula (I) having a weight average molecular weight Mw of 53,000 and a specific dispersion of 5.6 was used as a photosensitizer (IX ) Octamethylcyclotetrasilane shown by the formula 49 is used. The sample wafer was prepared, exposed, and developed under the same conditions as in Example 3-(1) except for the above conditions. As a result, the dose ff1D at which the residual film rate is 50% is room
J/cm2, and the dose 1 for resolving lum lines and spaces as designed was found to be 1600 mJ/cm2.

The experimental conditions and results of Example 3-(+) to Example 3-(6) are shown in Attached Table 2. For example, by comparing the results of Example 3-(+) and Example 3-(2), it can be seen that as the polysilane content increases, the resist sensitivity improves. Moreover, by comparing the results of Example 3-(1) and Example 3-(3), it can be seen that as the molecular weight of resin (I) increases, the resist sensitivity improves. Also,
By comparing the results of Example 3-(2) and Example 3-(4), it can be seen that there are differences in sensitivity depending on the type of polysilane.

? ZJL Example 4 <Two-layer resist pattern formation> (Example 4
-(1)) Film thickness after heat curing of odoresist (photoresist manufactured by Silapray) on silicon wafer (MP2400)
．． It was formed to have a thickness of 5 um. Below, for the sake of explanation, M
The P2400 photoresist layer is referred to as the bottom resist layer. Next, the resist solution prepared in Example 3-(+) was applied onto this lower resist layer by spin coating, and baked on a hot plate at 100°C for 1 minute to form a 0.2 um thick layer. After forming a resist film (hereinafter referred to as upper resist layer), Xe-H
Wavelength is 300n using q-clamp CM cold mirror
Exposure was performed using a contact method using ultraviolet rays of wavelengths below m.

The dose amount was 420 mJ/cm2. Next, the exposed wafer was developed for 20 seconds using a 1=1 (volume ratio) mixture of MIBK and IPA, and then developed for 20 seconds using IPA.
Rinsing was performed for 5 seconds. As a result, an upper resist pattern is obtained. Next, this wafer was placed on a hot plate for 10 minutes.
Baking was performed for 1 minute at a temperature of 0°C. Next, using the upper resist pattern as a mask, the lower resist was etched by 0□-RIE using a dry etcher DEM451u. The conditions are 0□ gas pressure and 1. O
Pa, gas flow rate is 20 SCCM, RF power is 9 degrees or 0.12 W/cm2, and etching time is 40 minutes.

A cross section taken parallel to the thickness direction of the two-layer resist pattern formed in this way was examined using a scanning electron microscope (SEM).
When observed using a , it was found that 0.25 um line and spaces were formed in a rectangular shape.

(Example 4-(2)) Same as Example 4-(+) except that the upper layer resist was formed using the resist solution prepared in Example 3-(2) and exposure was performed at a dose of 320 mJ/am2. A two-layer resist pattern was formed using the same process. When this two-layer resist pattern was observed with an SEM, it was found to be 0.0% as in Example 4-(1).
It was found that a line and space of 25 um was formed in a rectangular shape, and a hole pattern of 0.35 um in diameter was formed.

(Effects of the Invention) As is clear from the above description, the photosensitive resin composition of the present invention uses solvent-soluble polysilane as the photosensitizer contained therein, so that the film of the photosensitive resin composition contains Layer separation does not occur, and the photosensitizer does not precipitate from this film. Therefore, a homogeneous film can be obtained, which makes it possible to form a good resist pattern.

In general, because of their compatibility, it is possible to increase the content of polysilane to improve resist sensitivity, and because polysilane itself shows the same 02-RIE resistance as polysiloxane, the 02-RIE resistance of polysiloxane can be improved. Effects such as no reduction in performance can be obtained.

In addition, since polysilanes also absorb light with a wavelength of 250 nm, the photosensitive resin composition of the present invention may be compatible with KrF excimer laser lithography technology, and can be used for wavelengths of less than half a micron. It is promising as a resist that enables the production of ultra-highly integrated circuits.

[Brief explanation of the drawing]

1 (A) to (D) are diagrams for explaining the conventional method and the present invention, and process diagrams for explaining the resist process. Figures 2 (△) to (F) are diagrams for explaining the conventional method and the present invention. FIG. 2 is a process diagram for explaining a two-layer resist process. DESCRIPTION OF SYMBOLS 11...Substrate, 13...Metal film for wiring 13a...Gold layer wiring pattern 15...Resist film, 15a...Resist pattern 21...Substrate, 23...Thin layer wiring 25 ...Insulating film 27...Film 27a for second layer metal wiring...Second layer wiring 29...Step, 31...Thermosetting resin 3
3... Photosensitive resin, 33a... Photosensitive resin pattern 35... Two-layer resist pattern. 1 Shea 15a Resist pattern Process diagram for explanation of the resist process Figure 1 Indication of Chizuriuri Neho Seisho 1 Case 1988 Patent II No. 134264 2 Name of invention Photosensitive resin composition 3 Case of person making amendments Relations with Patent applicant 4 principal office (〒-105) 1-7-12 Toranomon, Minato-ku, Tokyo Name (029) Oki Electric Industry Co., Ltd. Representative Kushiro Polarization 4 agent 〒170 ffi (988) 5563
Address: 905-5 Ikebukuro White House Building, 1-20-5 Higashiikebukuro, Toshima-ku, Tokyo, S11 Kari-no-dori (1), N5u mJ% [i] on page 7, line 5 of the specification
I corrected it to '15nm.' (2), "Hydrolysis of alkoxy" on page 8, line 12 of specification M is corrected as "hydrolysis of alkoxysilane". (3), "Hydrolysis of alkoxysilane" on line 12 of page 8 of specification M. Kurohexashiran"tff' Corrected to Kurohexashiran J. that's all

Claims (6)

[Claims] (1) A photosensitive resin composition comprising a polysiloxane having a radically polymerizable substituent and a polysilane. (2) The photosensitive resin composition according to claim 1, wherein the polysiloxane is polysilsesquioxane. (3) The photosensitive resin composition according to claim 2, wherein the substituent on silicon of the polysilsesquioxane is a radically polymerizable group. (4) The photosensitive resin composition according to claim 1, wherein the polysilane is a solvent-soluble polysilane selected from disilane, linear polysilane, and cyclic polysilane. (5) The photosensitive resin composition according to claim 1, wherein the content of the polysilane relative to the polysiloxane is 5 to 50% by weight. (6) The photosensitive resin composition according to claim 3, wherein the polysilsesquioxane has a weight average molecular weight of 2,000 to 100,000.