JPS6186748A - Pattern-forming organic film - Google Patents

Abstract

PURPOSE:To obtain an org. film adapted to the formation of micropatterns of semiconductor elements and integrated circuits by incorporating a water-soluble org. polymer as a base polymer, a cross-linking agent, as the dissolution speed controller of this polymer, and a UV sensitive material. CONSTITUTION:The org. film 17 capable of forming the micropattern high in resolution and precision through UV exposure, development and the high output dry etching method can be obtained by coating a semiconductor substrate 1 with an aq. soln. contg. (1) a water-soluble org. polymer, such as polysaccharide, polyvinyl pyrrolidone, polyvinyl alcohol, or gelatine, preferably, pullulan represented by (C6H10O5)n.H2O; (2) the controller of dissolution speed of pullulan in the aq. soln. of alkali, composed of epichlorohydrine and (CH3)4NO; and (3) the UV sensitive material of a naphthoquinonediazide or aromatic bisazide compd. The obtained org. film is good in resistance to safe etching using no org. solvent.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to patterned organic films used in the fabrication of semiconductor devices and integrated circuits by patterning them using ultraviolet light.

Conventional configurations and their problems Semiconductor integrated circuits, especially complementary field effect transistors (0M
O8) In the integrated circuit manufacturing process, a first resist pattern is formed, and using this as a mask, P-type impurity ions are implanted to form the source/drain part of the P-channel MO8, and the relationship between the number of steps and alignment accuracy is determined. applying a second resist without removing the first resist from
A two-layer resist pattern process is required to form a pattern for ion-implanting N-type impurities into the source and drain portions of the N-channel MO3.

Generally speaking, in the integrated circuit manufacturing process, unevenness inevitably occurs on the substrate during the process, and after resist is applied, differences in the thickness of the resist occur at the uneven parts.
Pattern accuracy deteriorates and good line width control becomes impossible. In order to solve this problem, methods using two-layer or three-layer resists are being actively researched. Below are two examples,
This is shown in Figures 1 and 2.

First, a first example will be explained with reference to FIG. A thick layer of resist 3 is applied as a lower layer on the substrate 1 to absorb the level difference between the base layers (Fig. 1(a)'), and a twelfth layer of resist 6 is applied as the upper layer (Fig. 1(a)').
After forming a desired pattern on the second resist layer 6 (FIG. 1(b)), after performing DUV irradiation on the entire surface (FIG. 1(d)), by development processing. A pattern is transferred to the resist 3 (FIG. 1(e)).

(American TI Company, PCM method) Next, a second example will be explained with reference to FIG. Apply a thick layer of resistor on the substrate 1 to absorb the level difference between the base layers.
Figure (a)), the entire surface of the resist 9 was irradiated with UV, heat treatment was applied (Figure 2 (b)), and the second layer of resist 10 was applied on the upper layer (Figure 2 (C)). , a method in which a desired pattern is formed in the first and second resist layers by one development (FIG. 2(d)). (Matsushita Electric, DEM method) As in the above example, it has become increasingly necessary to overlap patterns in two or multiple layers of the same type of positive resist. However, simply forming multiple layers of the same type positive resist has the disadvantage that since the same solvent is used, they will dissolve each other and the first resist pattern will disappear.

This disadvantage will be further explained with reference to FIG. A first resist pattern 11 is formed on the substrate 1 (FIG. 3(a)).
). Then, baking is performed at about 140° C., and then a second resist 12 is applied. At this time, since the resist pattern 11 and the resist 12 are of the same type, they are dissolved into each other and the second resist 12 is applied. The resist pattern 11 becomes a deformed pattern 13, resulting in a pattern defect (FIG. 3(b)). Needless to say, it is meaningless to pattern the second layer of resist 12 in this state.

In addition, with conventional photoresists, after exposing and developing the photoresist to form a predetermined pattern, when using it as an etching mask, high-output dry etching (1) is required.
00W), the surface becomes rough, and the high heat generated at that time causes the pattern to sag. This phenomenon is a major barrier when forming fine circuits, and therefore reduces the output of the dry etching apparatus (160 to 20 oW) during etching. However, due to low-power dry etching, the etching rate naturally decreases, so
A decline in productivity is inevitable.

Furthermore, since conventional photoresists use organic solvents, they cannot be said to be sufficiently safe in use.

OBJECTS OF THE INVENTION As described in the conventional example, the present invention is capable of forming a multilayered resist pattern accurately and without defects, and that also prevents the resist pattern from becoming rough or thermally melted by high-power dry etching. The objective is to provide a patterned organic film that does not pose safety issues.

Structure of the Invention The present invention solves all conventional problems by using a base polymer made of water-soluble organic substances such as polysaccharides, proteins, polyvinylpyrrolidone, polyvinyl alcohol, and gelatin, and imparting photosensitivity to these. I was able to do that. In order to impart photosensitivity to a water-soluble organic substance (the following general formula (■)), for example, naphthoquinonediazide sulfonyl chloride (the following general formula (II)) may be synthesized. (General formula (■) below) Below is the margin (1) ' (II) @) In addition, during the usual 7-otresist synthesis, the above reaction is
Although it requires a large amount of temperature, pressure, and time, the reaction according to the present invention takes place in a very short time and easily because the reactant has an alcoholic hydroxyl group. This means that the patterned water-soluble organic film can be manufactured at low cost and with high throughput. Furthermore, a crosslinking agent and an epoxy compound consisting of an aldehyde compound and an alkali aqueous solution as a catalyst are added as dissolution rate controlling agents in water and aqueous alkaline solution, respectively. Since this photosensitive water-soluble polymer does not use organic solvents, it does not mix with other organic solvent-based resists even if it is applied in two or multiple layers, and there are safety issues. has also been resolved. On the other hand, since it contains many benzene rings and double bonds, it has high resistance to etching.

Description of Examples Example 1 First, a method for synthesizing an example of a pattern-forming organic film used in the present invention and its properties will be described.

Pour 100 cc of pure water (deionized water) into a beaker,
Average molecular weight 20 with sufficient heavy metals while keeping the temperature at room temperature
Add 2 oz of pullulan while stirring to dissolve 2 oz. Then, 100 cc of naphthoquinonediazide sulfonichloride solution was added as a substance sensitive to ultraviolet rays.
When mixed with the above-mentioned pullulan aqueous solution, it reacted immediately. Next, 10 cc of dialdehyde starch aqueous solution (10%) as a dissolution rate controlling agent in water, 10 cc of epichlorohydrin as a dissolving rate controlling agent in alkali, and 100 cc of ammonium tetramethyl hydroxide as a catalyst were added to the above reaction mixture. The mixture was stirred vigorously and allowed to stand for approximately 24 hours until completely dissolved.

The dialdehyde starch aqueous solution was used to control the dissolution rate of pullulan in water, and the epichlorohydrin and ammonium tetramethyl hydroxide were used to control the dissolution rate of pullulan in an alkaline aqueous solution. That is, dialdehyde starch reacts with the pullulan to form an acetal bond and exhibits poor solubility in water.
In addition, epichlorohydrin and tetramethyl hydroxide ammonium are converted into diol by tetramethyl hydroxide ammonium, which reacts with the excess dialdehyde starch aqueous solution to form an acetal bond, and the excess dialdehyde starch aqueous solution becomes an alkaline aqueous solution. prevent it from melting.

The aqueous solution after standing for 24 hours contained no gel-like substance and was stable in quality. It also had photosensitivity and was capable of forming positive fine patterns.

Example 2 Example 2 will be explained with reference to FIG. A pattern-forming aqueous solution is applied to a thickness of 1.2 μm on a semiconductor substrate, and after exposing and developing a desired pattern 14, baking is performed at 140°C. (FIG. 4(a)) Next, a positive type resist 16 was applied over the entire surface of the first pattern (FIG. 4(b)) to form a second pattern 16. (FIG. 4(C)) Since the pattern forming aqueous solution and the positive resist were not mixed with each other, a desired pattern could be formed. Note that even when a negative resist was used instead of a positive resist, the desired pattern could be formed without mixing with the pattern forming aqueous solution.

Example 3 Example 3 will be explained with reference to FIG.

A pattern forming aqueous solution is applied to a thickness of 1.2 μm on a semiconductor substrate, and is exposed and developed to form a desired pattern 17. (FIG. 5(a)) Then, the Si substrate is etched by high power (300 W) dry etching. Since the water-soluble film used in the present invention has excellent heat resistance and etching resistance, no smudges or irregularities were observed on the water-soluble film used as an etch mask, and the desired pattern could be etched. (
FIG. 6(b)) In any of Examples 1.2.3,
The base polymer may be a polysaccharide, protein, polyvinylpyrrolidone, polyvinyl alcohol, gelatin, etc. as long as it has an alcoholic hydroxyl group. Also,
Similar results were obtained for substances sensitive to ultraviolet light as well as for aromatic bisazide compounds.

Effects of the Invention According to the present invention, it is possible to stack different types of resist patterns without destroying or disappearing, and it can withstand high-power etching, and there are few problems from a safety standpoint. This greatly contributes to the yield and throughput of semiconductor integrated circuit manufacturing. In addition, the present invention can be applied to ordinary 7
The process of reacting a photosensitive substance, which is a troublesome step in the synthesis of photoresists, can be easily performed, leading to lower costs and improved throughput in the entire manufacturing process, so it has high industrial value.

[Brief explanation of the drawing]

Figures 1 (,) to (d) show that after a resist is applied on a substrate with steps, DUV is irradiated, a second layer of resist is applied and patterned, and the first layer of resist is applied by RIE. 2(a) to 2(d) are process cross-sectional views of a pattern forming method using a two-layer resist that transfers a pattern to a substrate. After coating a resist on a substrate with steps, UV irradiation, heat treatment, and Figure 3 is a process cross-sectional view of a pattern forming method using a two-layer resist, in which a second layer of resist is applied and a pattern is simultaneously formed on the first and second layers of resist through -times of exposure and development. b) is a process sectional view of a conventional method in which a resist is applied on a substrate, a desired pattern is formed, and then a resist of the same type is applied as an upper layer; FIGS. 4(a) to (C) ) is a process sectional view of an embodiment of a method of applying a pattern forming aqueous solution according to the present invention on a substrate to form a desired pattern, and then applying a resist as an upper layer to form a second desired pattern. Figure 5 (-)
(b) is a process sectional view of an embodiment of a method in which a pattern forming aqueous solution according to the present invention is applied onto a substrate, a desired pattern is formed, and then Si etching is performed. 1... Board, 12.16... Pattern. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
Figure 3 Figure 4 Figure 5

Claims (5)

[Claims] (1) Dissolution rate of the base polymer in the alkaline aqueous solution consisting of a base polymer that is a water-soluble organic substance, a crosslinking agent that acts as a dissolution rate controlling agent for the base polymer in water, an alkaline aqueous solution as a dissolving medium, and an epoxy compound. A patterned organic film comprising a control agent and a substance sensitive to ultraviolet light. (2) The pattern-forming organic film according to claim 1, wherein the water-soluble organic substance contains at least one of polysaccharide, protein, polyvinylpyrrolidone, polyvinyl alcohol, and gelatin. (3) The water-soluble organic substance has the general formula (C_6H_1_0O_5
) The pattern-forming organic film according to claim 1, which is pullulan, a polysaccharide represented by n·H_2O. (4) The pattern-forming organic film according to claim 1, wherein the substance sensitive to ultraviolet rays contains naphthoquinonediazide or an aromatic bisazide compound. (5) The pattern-forming organic film according to claim 1, wherein the substance sensitive to ultraviolet rays instantly reacts with a water-soluble organic substance and contains the reaction product as a main component. .