JPS63316846A - Formation of resist pattern - Google Patents

Abstract

PURPOSE:To enhance the accuracy and stability of a mask with respect to a lower layer resist by patterning an upper resist and forming a silicon oxide film on the surface thereof. CONSTITUTION:The 1st resist layer 11 having the nearly flat surface is formed on a substrate 1 having steps 2 and the 2nd resist layer 12 consisting of an Si-contg. photoresist (e.g.: the polymer expressed by the formula) is formed thereon. The layer 12 is then patterned and thereafter, for example, far IR rays are projected over the entire surface to improve the heat resistance of the layer 12 and to form an SiOx film 13 thereon. The layer 11 is thereafter subjected to anisotropic dry etching in oxygen plasma with the layer 12 formed with the layer 13 as a mask to form the resist pattern 14. Since the conditions for forming the above-mentioned film 13 can be so set as to attain a desired film thickness, the mask of the layer 11 is stably formed with the high accuracy.

Description

[Detailed description of the invention] The present invention will be explained in the following order.

A. Industrial application field B. Essentials of the invention C. Prior art D. Problem to be solved by the invention E. Means for solving the problem (Fig. 1) F. Effect G. Example G1 First resist layer G2 Second resist layer G3 Resist layer patterning procedure H Effect of the invention A Industrial application field The present invention is directed to a method for forming a resist pattern used as a mask for various types of microfabrication, including manufacturing processes of various semiconductor devices. involved.

B. Summary of the Invention The present invention provides a method for forming a resist pattern on a substrate having an uneven surface, that is, a step, by forming a first resist layer so as to fill the step so that the surface thereof is flat. , a single layer of a second resist containing silicon is deposited on this, the second resist layer is exposed to light in a required pattern, and developed to form a predetermined pattern.
In particular, after the process of forming a film on the surface, the first resist layer is anisotropically etched in oxygen plasma using the pattern formed by the second resist layer as a mask, so that the edge of the pattern can be easily cut. In other words, a highly sharp resist pattern is formed.

C. Prior Art In the manufacturing process of various semiconductor devices such as IQ+density large-scale integrated circuit LSI, ultra-fine resist patterns for various purposes are required, such as resists for selective dry etching and resists for selective ion implantation.

When forming this resist pattern, most of the resist patterns have unevenness, that is, a step, formed on the surface of the substrate to be adhered through various manufacturing steps. When there are steps like this on the surface to which the resist is applied, simply apply a photoresist layer with a uniform thickness, which is commonly done! In the method of forming a resist pattern using light and a developing process, coating unevenness occurs due to the presence of steps.

It is difficult to obtain highly accurate and sharp ultrafine patterns due to uneven exposure.

On the other hand, for example, published by Kogyo Kenkyukai, Electronic Materials 4, 1
986. A two-layer resist method is known, which is also described on page 47. This method is based on a structure in which two types of resist layers are laminated, and the steps on the substrate surface are filled with the lower first resist layer to flatten the surface, and then a photoresist is applied on top of this. A flat second resist layer with a uniform thickness is formed by the process, and the required pattern is exposed and developed to form a pattern. Using this as a mask, the first resist layer below is exposed to oxygen. Anisotropic dry etching in plasma (hereinafter referred to as 02-
There is a two-layer resist method in which patterning is performed by RIE (referred to as RIE). In this case, the upper second resist layer is
The pattern is formed by the optical photographic technique using exposure and development as described above, but as mentioned above, this upper second resist layer is a flat layer with a uniform thickness, and a thin layer. As a result, a fine pattern can be formed with high accuracy and sharpness, and accordingly, the pattern of the W42 resist layer, which is patterned by 0z-RIE using this first resist layer as a mask, also has a high precision. It is said that fine patterns with high accuracy and sharpness can be obtained.

However, when using this method, in reality, during the 02-RIE operation of the lower first resist layer using the upper second resist layer as a mask, the upper second resist layer is eroded and ultra-fine particles are formed. There is a problem with its applicability to the pattern.

On the other hand, silicon S is used as the upper second resist layer.
It is conceivable to use a t-containing photoresist. In this Si-containing resist, St was changed to S during the 02-RIE process.
Since iOx, for example, Si(h), is mineralized and becomes stable in an oxygen atmosphere, it is thought that the underlying first resist layer can be stably patterned by 02-RIB using this as a mask. However, in this case, Also, in practice, S
In order for the Si in the gold-containing photoresist layer to become inorganic, (7) H (hydrogen) and C (carbon) in this resist r-1h disappear as O7,C(ht) and the Si becomes inorganic.
Since Ox is generated, the width and thickness of the photoresist layer decreases by the time this SiOx is generated, so-called curvature, which is large.
2-The membrane during RIE is 02
Because it occurs unstable depending on the conditions of RIE,
There is a problem in that the function as a patterning mask for the underlying resist layer and the pattern accuracy are reduced, and the accuracy of the obtained resist pattern and the edge of the pattern are cut, that is, the sharpness is reduced.

D Problems to be Solved by the Invention The present invention avoids the above-mentioned problems in forming an ultra-fine resist pattern on a substrate having steps as described above, and provides a highly accurate and sharp ultra-fine pattern. To provide a method for forming a resist pattern that can reliably form a resist pattern.

E. Means for Solving the Problems The present invention, as shown in an enlarged cross-sectional view in FIG. a step of forming a flat first resist layer (11); a step of forming a second resist layer (12) made of a silicon-containing photoresist on the first resist 1Vi (11); The second resist layer (12) is subjected to pattern exposure and development to form a pattern.

Further, in the present invention, this patterned second resist layer (12) is subjected to a treatment step of converting its surface itself into SiO2 or 5tyx, as shown in FIG. 1B, to form a silicon oxide film. (13) is formed.

Then, as shown in FIG. 1C, this patterned second
Using the resist 1i (12) as a mask, a required resist pattern (14) is formed by patterning the first resist layer (11) by anisotropic dry etching using etching 02RIE in oxygen plasma.

According to the method of the present invention, the resist 141 (12) of fA2 is formed of a St gold-containing photoresist, and moreover, the first resist jtj (11) of the lower layer is thereby
Prior to RIE, the patterned St gold-containing photoresist m (12) is coated with a substrate 11 on which Si02 or SiOx has been generated on the surface itself in a separate process.
R (13) is actively formed, and this film (13) can be ensured to the required thickness by setting the strip 1 to the required conditions for forming this film (13). In other words, the amount of disappearance of H20↑+ CO2↑ is accurately calculated as
In other words, since the film thickness can be set by accurately predicting the film thickness in advance, it can be stably formed as a mask for 02 RIE on the underlying first resist layer (11) with high commercial accuracy.

G Example G1 First resist l- The step (2) on the surface of the substrate (1) is filled with, for example, a positive type L/-,;:At, manufactured by Tokyo Ohka Co., Ltd., product name ONPM800, is applied thickly. A first resist layer (11) having a flattened surface is formed by coating the resist layer with a thickness of 2 .mu.m and baking at 200.degree.

G2 Second resist layer A second resist layer (12) made of siloxane thread positive type photoresist is applied to a thickness of 0.2 to 0.5 .mu.- on the first resist ff1 (11). This resist layer (12) is composed of g-line (wavelength 436n), 1st (365nm)
m), that is, a novel silicon atom-introduced phenol derivative-quinonediazide compound that exhibits high sensitivity to ultraviolet light emitted by a normal mercury lamp. To explain this resist, it has the general formula +11 (in both formulas, R1 and R9 are lower alkylene groups, R2゜R3
, R4, R10, R11 and RL2 are H, 011, CL
or C) 120H, R6-R8 is a lower alkyl group, R1
3 is CI2 or CIh0CH2, A is phenol, 1-
represents a phenol derivative having 3 substituents or H (R14 is a lower alkylene group, RIS, Rs6 and Rh represent a lower alkyl group), X is a number greater than O and 1 or more F, and Y is 0 or 1- It consists of a polymer having at least one of the units represented by X).

Examples of the phenol derivatives constituting this resist material include 0-lm- and p-cresol, xylenol, and resorcinol. Further, in each of the above formulas, the ratio of X to Y is arbitrary, but in consideration of developability in an organic alkali aqueous solution, Y is preferably 0.7 or less.

Furthermore, examples 1 to 3 of manufacturing methods of this resist will be explained.

Example 1 First, equation (3) The monomer shown was synthesized by the following method.

50 g of 3-hydroxybenzyl alcohol in a 500+ wl capacity three-necked flask equipped with a reflux condenser.
(0.4 mol), benzyl chloride 51 g (0.4 m
ol), 110 g of anhydrous potassium carbonate (0,8■oO
A mixture of 1 and 200 ml of anhydrous acetone was refluxed for 6 hours to react. The generated benzyl ether compound was extracted with ether and dried with magnesium sulfate (yield 90%).Next, 30g of this compound (0.14sol
) was dissolved in carbon tetrachloride, and 16.7% of phosphorus tribromide was dissolved under water cooling.
g<0.062 mol) was added dropwise over 2 hours to react, and then the solution was poured into ice water to decompose unreacted substances. The produced bromide was purified by silica gel chromatography using n-hexane as the developing solvent (yield 60%).Next, it was placed in a 500 ml five-loop flask each equipped with a nitrogen blowing tube, a reflux condenser, and a dropping funnel. Add 1.93 g (0,079 gram atom) of magnesium and 40 m+1 of anhydrous ether, and cool with water.
20 g (0.07 sol) of the above bromide was dissolved in 100 μl of anhydrous ether and stirred for about 2 hours. After this reaction for 2 hours, dimethylchlorosilane 6
．． 6 g (0.07 sol) was added dropwise and left to stand at room temperature overnight, followed by distillation purification under reduced pressure (0.6 maHg).

(boiling point: 140°C) (yield: 60%).

Next, 5 g (0,019 mol) of this distilled product was
After 100 mg of the 5% palladium-carbon catalyst was dropped into ethanol dispersed therein, 20 g of the 5% palladium-carbon catalyst and several drops of concentrated hydrochloric acid were further added to carry out hydrogenation. The obtained product was purified by silica gel chromatography using n-hexane as a developing solvent to obtain a monomer represented by the above formula (3) (yield = 1
00%).

The analytical values for this monomer were as follows.

Infrared absorption spectrum (cm-'): 3350
(-OH), 2950 (CH2), 1250.85
0, (Si (CH3)3)1050 (St -0
-Si), "H-NMR spectrum (δ) ppm = 0.04
(12HSS, (CH3)2), 2.08
(4H, S.

-Odor 2), 5.16 (2H, S, -4), 6.4
~7.4 (8H,m, benzene nucleus) (see Figure 2).

1JC-NMR spectrum (see Figure 3).

Precision molecule IL two-point calculation value 346.1447, actual measurement value 346
．． 1474° In addition, in the synthesis of the above tlLI body, 3
If a compound obtained by replacing the benzene nucleus of 3-hydroxybenzyl alcohol with f is used instead of -hydroxybenzyl alcohol, an IRi form corresponding to this compound can be obtained.

Next, 5.4 g (0,0156 seol) of the monomer of the above formula (3) which is siloxane thread phenol, 1.14 g formalin (37% aqueous solution), 6 g ethyl cellosolve acetate, and 27 g Schella acid dihydrate were added. 100m
The resist was placed in a 1-volume eggplant-shaped flask, heated and stirred at 110°C for 8 hours to react, and the reaction product was washed with water and purified under reduced pressure to obtain 1, the resist of this example mainly consisting of the polymer represented by formula (4). I got the material.

The molecular weight of this resist material was determined by gel permini-silicone chromatography using monodisperse polystyrene as a standard.
w = 5,200, M n = 1.100, and M w /M n -4,75.

Example 2 In this case, a resist material was obtained in the same manner as in Example 1, except that heating and stirring were performed for 14 hours instead of 8 hours.

The molecular weight of this resist material, determined in the same manner as in Example 1, was M w = 28,300. M n = 2.200
and M w /M n = 12.9.

The analytical values of the polymers obtained in Examples 1 and 2 were as follows.

Infrared absorption spectrum (cm-”): 3300
(-OH), 2950 (C112), 1250.8
50, (Si(CH3)2)1050 (-S
t-0-5i), “H-NMR spectrum (δ>
ppm: o, o4~0.2 (br, S-C1
13), 6.2-6.8 (br, benzene nucleus).

In addition, in Examples 1 and 2, some polymers having a repeating unit in which a methylol group was introduced into the benzene nucleus of the polymer of formula (4) above were also produced.

In addition, in Examples 1 and 2, when the polymerization reaction is carried out in an alkaline medium, the polymer of the formula (4) is mainly produced instead of the polymer of the formula (4).

Example 3 6 g m-1-limethylsilylmethylphenol (0,0
33*ol), the monomer obtained in Example 1, the above formula (
3) siloxane thread phenol 5.71g (0,01
65 mol), 3.61 g of formalin (37% aqueous solution), 13 g of ethyl cellosolve acetate, and 87 mol of oxalic acid dihydrate were placed in a 100 ml eggplant-shaped flask, heated and stirred at 110°C for 13 hours, and reacted to form the formula (5 ) A resist material of this example consisting of a copolymer represented by the following was obtained.

The molecular weights of this resist material determined by the same method as in Example 1 were M w -5,000, M n -2,000, and Mw/Mn = 2.5.

Moreover, the analytical values of this copolymer were the same as in Example 1.

The resistance of the polymers obtained in each case to 02 RIE was evaluated using Microposit 1, a commonly used commercial product.
When compared with 400 (product name of Sisobray),
The following results were obtained.

However, the etching conditions are: oxygen partial pressure 10mm, 11g,
The fg elementary flow rate was 50 SCCM and the RF output was 0.1 M-.

For resist 1-(12), for example, a cellosolve acetate-xylene solution prepared by adding 15i% of a sensitizer (quinone diazide compound) to the polymer obtained in Example 1 was further spin-coated and dried at 80°C for 20 minutes. It was formed by

G3 Resist Patterning Procedure The procedure for patterning the resist layers (11) and (12) laminated on the substrate (1) described in items 01 and 02 above is first performed using, for example, a mercury lamp, that is, G-ray.

The Si-containing second resist m (12) is pattern-exposed using a reduction projection exposure apparatus using a light source that emits i-line. Then, this pattern-exposed second resist l
- Develop jwi(12). When the resist material of the second resist ii# (12) is a resist made of the novel Si-conducting pheno-based resin quinone diazide compound described in the above item 62, this development is performed using an organic alkaline developer solution of This developer, which is performed using a 5% (W1 amount) TMAH aqueous solution, may be composed of, for example, a mixture of 10% TMAH aqueous solution manufactured by Tokyo Kasei Co., Ltd. and 2.38% (weight) of NMD-3 manufactured by Tokyo Ohka Co., Ltd.

Next, the second resist layer (12) developed in this way, that is, patterned, is irradiated with deep ultraviolet rays over the entire surface using a resist hardening device manufactured by Fagin.
When doing this, the heat resistance of the second resist layer (12) improves, and an increase in the oxygen atom concentration and a decrease in carbon atoms on the surface of the second resist layer (12) itself are observed. By SiOx I! It was confirmed that (13) was generated.

Next, using this second resist layer (12) as a mask,
The first resist layer (11) below it is patterned by 0z-RIE.

In the above example, a new Sil#-containing ferraphenol-based resin diazide compound is used as the resist containing St constituting the second resist layer (12). For example, a resist containing a siloxane polymer disclosed in JP-A-61-188539 can also be used.

Effects of the invention According to the method of the invention, the second resist layer (12) is made of Si.
02 RI.
In advance, S is applied to the surface of the patterned Si-containing photoresist layer (12) in a separate process.
iOx e.g. S i02 is generated 151! (13
), is actively formed, and this film (1
3), by setting the conditions for forming it to the required conditions, it is possible to ensure the required thickness (in other words, ) 120 t. Since the amount can be predicted and set accurately in advance, it can be stably and accurately formed as a mask for 02 RIE for the first resist layer (11) below.

[Brief explanation of drawings]

Figures 1A-C are process diagrams of the method of the present invention, and Figures 2 and 3 are H-NMR spectra and C-NMR of monomers used to explain the second resist layer of the method of the present invention. It is a spectrum diagram. ([) is the substrate, (2) is the step, (11) and (12) are the first and second resist layers, and (13) is the silicon oxide test object.

Claims (1)

[Claims] A step of forming a first resist layer with a substantially flat surface on a substrate having steps, and forming a second resist layer of a silicon-containing photoresist on the first resist layer. a step of patterning the second resist layer, a step of pattern exposure and development, a step of forming a silicon oxide film on the surface of the second resist layer, and then using the second resist layer as a mask. A method for forming a resist pattern, comprising the step of patterning the first resist layer by anisotropic dry etching in O_2 plasma.