JPS60262151A - Intermediate layer for 3-layer resist material and method for using it - Google Patents

Abstract

PURPOSE:To enhance resistance to O2 and RIE by forming on a substrate a lower resist layer made of an org. polymer, an intermediate layer made of a specified organopolysiloxane, and an upper resist layer made of a polymer brigeable with radiation. CONSTITUTION:The intermediate layer formed on the lower resist layer made of an org. polymer formed on a substrate is made of an organopolysiloxane represented by the formula in which R is a hydrocarbon, H, OH, or alkoxy group, and m+n+p+q=1, m>0, n,p,q>=0, and (p+q)/(m+n)>=0.8. The upper resist layer made of a polymer bridgeable or decomposable with radiation is laminatd on it, and it is exposed and developed to form a desired pattern. The intermediate layer is etched with F-contg. plasma, and the lower resist layer is etched to form the 3-layer resist pattern.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to lithography technology for forming highly accurate and fine resist patterns on substrates in the manufacture of various solid-state devices including semiconductor integrated circuits. ,
In particular, it relates to materials for multilayer resists and methods of using the same in pattern formation.

2. Description of the Related Art In the manufacture of semiconductor integrated circuits, etc., the degree of integration is increasing year by year, and with this, high precision and microfabrication are required. Furthermore, lithography methods have been developed in a variety of ways, including a reduction projection exposure method using near-ultraviolet light, an electron beam direct writing method, and an X-ray exposure method.

However, the substrate level difference that occurs during the device manufacturing process causes the thickness of the resist layer coated on the substrate to vary, which causes a problem in that the dimensional accuracy of the resist pattern decreases regardless of the exposure method. In addition, as pattern dimensions become finer, standing wave effects due to light reflected from the substrate in the case of light exposure, and proximity effects due to reflected electrons in the case of electron beam exposure, are major deteriorations in the accuracy of formed patterns. This is becoming a major factor, and countermeasures against this problem are urgently needed.

As a solution to these problems, there is a so-called three-layer resist in which three layers of films are laminated. FIG. 1 is a sectional view showing the structure of this three-layer resist. As is clear from FIG. 1, the three-layer resist is composed of a substrate 1 to be processed, a lower resist layer 2 made of an organic polymer material, a thin film material 3 used as an intermediate layer, and an upper resist layer made of a radiation-sensitive polymer material. , as the upper resist layer, for example, AZ-
An ultraviolet resist such as 1350, an electron beam resist such as PMMA, an X-ray resist, etc. are applied. In this three-layer resist, the thick lower resist layer 2 effectively flattens the substrate step and also separates the upper resist layer 4 to be exposed from the substrate, so that all of the above problems can be solved.

Pattern formation of the three-layer resist is carried out by first forming a predetermined pattern on the upper resist layer 4 by a known exposure method, and then sequentially etching the intermediate layer 3 and the lower resist layer 2. Thereafter, the substrate is etched using the three-layer resist pattern as a mask, and the intermediate layer 3 and lower resist layer 2 are removed to complete the process.

As an etching method, reactive ion etching (RIE) with little difference in dimensional conversion is mainly used, and in particular, reactive ion etching (02RIE) using oxygen gas is usually used for etching the lower resist layer. .

In addition, since the intermediate layer functions as a mask when etching this lower resist layer, 02RI is used as the intermediate layer.
Materials with high E resistance, such as inorganic materials such as Sl, 3102, and AI, are used.

As a method for forming this intermediate layer, generally any one of a CVD method, a sputtering method, and a vapor deposition method is used. However, recently, organopolysiloxane (commonly known as silicone resin), which can be formed into a film on a substrate by spin coating like ordinary organic polymers and has chemical properties similar to inorganic materials, has been used as the thin film material. It has become possible to do so.

This is because, according to the spin coating method, the formation time is extremely short compared to the vapor deposition method, the CVD method, and the spuck method, and the thin film can be formed with a simple operation.

However, with conventional organopolysiloxanes, etching for pattern formation does not proceed smoothly.
Therefore, it has the disadvantage that fine patterns cannot be formed and that the throughput is low.

Problems to be Solved by the Invention As mentioned above, it is possible to improve the problems such as variations in the film thickness of the resist layer coated on the substrate and a decrease in the dimensional accuracy of the resist pattern due to the substrate level difference that occurs during the device manufacturing process. There were still issues to be solved.

As one solution to this problem, a so-called three-layer resist in which three layers of films are laminated is known and used. Here, organopolysiloxanes have recently been used to form interlayers by spin coating, but as already mentioned, there are still some problems that need to be improved.

SUMMARY OF THE INVENTION In order to solve the above-mentioned drawbacks, it is an object of the present invention to provide an intermediate layer material for a three-layer resist made of organopolysiloxane having a high etching rate. Another object of the present invention is to provide a method for utilizing the intermediate layer material for a three-layer resist.

Means for Solving the Problems Under these circumstances, the present inventors conducted various studies in order to develop a new intermediate layer material for three-layer resists that can eliminate the various drawbacks of the conventional organopolysiloxanes. As a result of research, it was found that the organopolysiloxane of general formula N) described in detail below is extremely effective for achieving the above object, and the present invention was completed.

Therefore, the organopolysiloxane useful as the intermediate layer material for the three-layer resist of the present invention has the following general formula % formula % (): ) (R3i○3/2)p. In the general formula (I), R may be the same or different, and is one selected from the group consisting of a hydrocarbon group, hydrogen, a hydroxyl group, and an alkoxy group, and m + n + p +
It is an organopolysiloxane material represented by q=1, m>Q, nS PS q≧0, and (p
It is characterized by +q>/Cm+n)≧0,8.

On the other hand, the method for utilizing the intermediate layer material for a three-layer resist of the present invention is to provide a substrate with a lower resist layer made of an organic polymer material, an intermediate layer, and an upper resist layer made of a polymer material crosslinked or decomposed by radiation. A desired pattern is formed in the upper resist layer by exposing and developing the upper resist layer, etching the intermediate layer with gas plasma containing at least fluorine, and then removing the lower resist layer. When forming a three-layer resist pattern by etching, the present invention is characterized in that alkaline polycyclohexane of the general formula (I) is used as the intermediate layer material.

In addition, in the substituent R of the general formula (I), the hydrocarbon group is preferably a saturated or unsaturated lower hydrocarbon group such as methyl, ethyl, vinyl, etc., and the alkoxy group is, for example, methoxy, ethquin, etc. Lower alkoxy groups such as are preferred.

Last week, the organopolysiloxane of the present invention has the general formula (1)
As is clear from the above, it is a material with an 81-C bond in the main chain and an organic group in the side chain, and has properties that are different from ordinary organic polymers with a backbone of C-C bonds, such as high 0□RIE resistance. It is the material. Chemical properties are rather 510
2, and therefore RIE with fluorine-containing gas is used as etching for pattern formation, generally CF, R
11 is used.

Table 1 shows the etching rates of various organopolysiloxanes by CF and RIE. Here, m1n, p, q are (
The etching conditions are CF, flow rate 50 sec, gas pressure 0.0.
1 Torr and high frequency power of 100W.

1 0, Q3 0.0B 0.86 0.03 B, 1
8402 0.03 0.09 0.88 D, 00
7.3 7403 0.39 0.01 0.0.8
0.52 1.5 4704 0.24 0.05
0.41 0.30 2.4 4305 0.17 0
．． 33 0,21 0.29 1.0 3236 0.
13 0.52 0.20 0.15 0.54 ~8
77 0.13 0.70 0.02 0.15 0.
53 ~908 0.20 0.50 0.04 0.
26 0.42 - 47 From Table 1 above, it can be seen that when p and q are large, that is, when the value of (p+q)/(m+"n) is large, the etching rate is high. The etching is performed using the pattern of the upper resist layer as a mask as described above.

Therefore, the etching rate of the organopolysiloxane needs to be equal to or higher than the etching rate of the upper resist layer. UV resist (usually considered to have the highest etching resistance) AZ-135
When the etching rate of C1 was measured under the same conditions, it was 2
30 A/min, and therefore the etching rate of the organopolysiloxane must also be at least 230 people/min.

Figure 2 shows the relationship between (p+q)/(m+n) and etching speed. From the results in Figure 2, if we consider (p+q)/(m+n) that satisfies the above requirements, (p+q)
/ (m+n)≧0.8, and it can be seen that an organopolysiloxane satisfying at least this condition must be used for pattern formation.

i As above, the larger the value of p−q, the more
You can see that the speed is also faster. This is due to the following reasons.

That is, the binding energy is S i-C (69,3Kcal
/mol) is 81-〇(88,2Kcal/
mo] ) smaller and easier to cut. Therefore, the F atom, which is a reactive species, first passes through the following transition state and dissociates C.

F+−○δ−−3iδ10−C→[F SIC]→1 06− ○ 1 10−3i −F + C In this case, the larger the number of oxygens adjacent to Sl, the more 3
Since the degree of 164 polarization increases, it becomes easier for F to approach like a charge nucleus. Since a reaction occurs as a result, the degree of polarization is thought to influence the reaction rate. Therefore, the reaction rate is R31Oa/2>R2S i O>R3S io
, 7□. On the other hand, in the case of 5102, although it does not contain C, the degree of polarization is the highest, so RS
It is thought that the etching rate is high, similar to i 03/2.

From the above considerations, it is considered that the more S I 02 , R3] 03/2, the faster the etching rate.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the scope of the present invention is not limited by these Examples.

Example 1 On a substrate on which a 0.5 μm thick aluminum thin film was deposited,
As the lower layer resist, a photoresist manufactured by Shipley Co., Ltd.)' A
Z-1350 was spin-coated to a film thickness of 1.5 μm, and heat-treated at 150° C. for 30 minutes in a nitrogen atmosphere. Subsequently, organopolysiloxane (p+q)/(m+n)-8,1 was spin-coated to a film thickness of 0.2 μm, and the film was coated at 150°C under a nitrogen atmosphere for 30 minutes.
Heat treatment was performed for 0 minutes. Next, as the upper layer resist, ΔZ-1
350 was spin-coated to a thickness of 1 μm, exposed to ultraviolet light, and developed to form a resist pattern with a width of 1 μm. Using this resist pattern as a mask, the organopolysiloxane was etched by performing R'IE under conditions of high frequency power of 1001'l, CF4 flow rate of 50 sccm, and gas pressure of 0.0 ITorr.

Subsequently, the lower resist layer was etched by changing the CF to 02 to form a three-layer resist pattern with a width of 1 μm.

Example 2 Δ
After spin-coating Z-1350 to a film thickness of 1.5 μm and heat-treating it at 150°C for 30 minutes, an organopolymer of (p+q)/(m-n)-8,1 was formed. Siloxane was spin-coated to a film thickness of 0.2 μm, and heat-treated at 150° C. for 30 minutes. Next, CMS, which is an electron beam negative resist, was used as a two-layer resist.
A resist pattern with a width of 0.5 μm was formed by spin coating to a thickness of 4 μm, electron beam exposure, and development. Next, using the resist pattern as a mask, RIE was performed under conditions of high frequency power of 1001!1% CF, flow rate of 50 sec, and gas pressure of 0.01 Torr to etch the organopolysiloxane, and then CF and Q2
By switching to etching and etching the lower resist layer, a three-layer resist pattern with a width of 0.5 μm was formed.

Although AZ-1350 was used as the material for forming the lower resist layer in the above embodiments, any material can be used in the present invention as long as it can be coated with good adhesion to the substrate surface and can be easily etched by the 02RIE method. . Therefore, in addition to commercially available resist materials, basically all coatable organic polymer materials can be applied to the present invention. As for the upper layer resist, all known ultraviolet resists, X-ray resists, f' electron beam resists are applicable.

Further, as the gas for etching organopolysiloxane, all gases containing fluorine can be used in the present invention, including the C F 4 described in the Examples. It is also effective to mix gases such as oxygen, hydrogen, helium, etc. in order to control the processed shape and etching rate.

Furthermore, in order to improve the exposure characteristics of the upper resist layer, it is also possible to include other substances in the organopolysiloxane. It is particularly effective to include a light absorbing material.

According to the present invention, an alkaline polysiloxane as an intermediate layer material for a three-layer resist as shown by the general formula (1) is provided, which is superior to conventionally known organopolysiloxanes. Etching for forming a pattern does not proceed smoothly or a fine pattern cannot be formed, and extremely good etching is possible.

Therefore, when the organopolysiloxane of the present invention is used as an intermediate layer material for a multilayer resist, not only can the throughput be greatly improved, but also fine and highly accurate pattern formation using the multilayer resist can be ensured. will be guaranteed.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the structure of a three-layer resist, and FIG. 2 is a diagram showing the relationship between (p+q)/(m+n) and etching rate. (Main reference numbers)] Substrate 2 Lower resist layer 3 Intermediate layer 4 Upper resist layer Patent applicant Nippon Telegraph and Telephone Public Corporation Representative Masahiko Arai Pimata shoulders 3 - 11 middle eyebrows 4 - 11 upper eyebrows and 1 eyebrow

Claims (2)

[Claims] (1) The following general formula: % formula %)) However, in the formula, R may be the same or different and is a type selected from the group consisting of a hydrocarbon group, hydrogen, hydroxyl group, and alkoxy group, m+n+p+q=l, An intermediate layer material for a three-layer resist, characterized in that it is made of an organopolysiloxane material represented by m>Q, n1p1q≧0, and (p1q)/(m+n)≧0.8. (2) A lower resist layer made of an organic polymer material, an intermediate layer, and an upper resist layer made of a polymer material that can be crosslinked or decomposed by radiation are sequentially formed on the substrate, and the upper resist layer is exposed and developed. When forming a three-layer resist pattern by forming a desired pattern on the upper resist layer, etching the intermediate layer with a gas plasma containing at least fluorine, and then etching the lower resist layer, the intermediate layer As a material for use, the following general formula: % formula %)) However, in the general formula, R may be the same or different and is a type selected from the group consisting of a hydrocarbon group, hydrogen, hydroxyl group, alkoxy group, m+n+p+Q=1
．． , m>Q, TIS+)%q≧0, and use of the above organopolysiloxane material characterized by using an organopolysiloxane material in which (p+q)/(m+n)≧0.8. Method.