JPH0287146A - Manufacturing method of semiconductor device - Google Patents

Abstract

PURPOSE:To improve the dimensional accuracy of a resist pattern by depositing a 2nd resist contg. a dissolution inhibitor at a high ratio onto the surface of a 1st resist contg. the dissolution inhibitor at a low ratio. CONSTITUTION:The 1st resist 2b contg. the dissolution inhibitor at the high ratio is deposited onto the surface of the 1st resist 2a contg. the dissolution inhibitor at the low ratio at the time of forming the resist pattern on the surface of a semiconductor wafer. Since the 2nd resist 2b can be deposited at a uniform film thickness on the surface of the 1st resist 2a, the residual film thickness on the resist surface of the unexposed part can be uniformly increased over the entire surface of the semiconductor wafer. The dimensional accuracy of the resist pattern is improved at a good yield in this way.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable to semiconductor devices! ! The present invention relates to manufacturing technology, and in particular to technology that is effective when applied to resist deposition used in the manufacturing process of semiconductor devices.

[Conventional technology]

As resists used in the manufacturing process of semiconductor devices, novolac resin-based positive resists and cyclized rubber-based negative resists are known.

In particular, the former novolac resin-based positive resist has good resolution because it does not swell during development and also has excellent dry etching resistance, so it has become the mainstream resist material used in the manufacturing process of semiconductor devices.

In the above-mentioned novolac resin-based positive resist, the resist in the unexposed areas is insolubilized by the dissolution inhibitor, so it dissolves only slightly in the developer, whereas in the exposed areas, the dissolution inhibitor in the resist decomposes. Therefore, a desired resist pattern is formed by utilizing the property of quickly dissolving in a developer.

By the way, it has been found that when attempting to form a fine pattern using a rib resist containing a dissolution inhibitor as described above, the following problem occurs.

That is, in the developing process of the above-mentioned dissolution inhibitor-containing resist, as shown in FIG. The development time t is set such that the resist is completely dissolved (residual film thickness=0) and a certain amount of resist remains in the unexposed areas.

However, for example, in resists for electron beam direct writing,
When developing with a high concentration developer to obtain high sensitivity, dissolution of the resist progresses even in unexposed areas, so as shown in Figure 5, the effects of diffraction and scattering are particularly important. There has been a problem in that the film thickness of the resist 10 is noticeably reduced at the ends of the unexposed portions, which are susceptible to damage, and as a result, the dimensional accuracy of the resist pattern is reduced.

As a countermeasure to this problem, Japanese Patent Application Laid-Open No. 55-105326 proposes forming the resist into two layers, and making the base resin of the upper resist layer higher in polymer than the base resin of the lower resist layer.

This takes advantage of the fact that when the base resin of the upper layer resist is made into a polymer, the dissolution rate of the upper layer resist in the developer decreases. The idea is to reduce the loss of resist film in unexposed areas by amplifying the difference between the two.

At that time, as a means to polymerize the base resin of the upper resist layer, there are methods to extract and remove low molecular weight components on the resist surface by exposing the resist surface to an organic solvent such as chlorobenzene, or to irradiate the resist surface with ultraviolet rays. A method is disclosed in which the base resin on the resist surface is partially polymerized.

[Problem to be solved by the invention]

However, according to the inventor's study, the method of extracting and removing low molecular weight components on the resist surface and the method of partially polymerizing the base resin on the resist surface do not involve polymerizing the resist over the entire surface of the semiconductor wafer. However, it is not possible to improve the dimensional accuracy of the resist pattern formed on the surface of the semiconductor wafer with a good yield. There wasn't.

The present invention has been made in view of the above problems, and its purpose is to provide a technology that can improve the dimensional accuracy of a resist pattern formed on the surface of a semiconductor wafer with a high yield. .

The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[Means to solve the problem]

A brief overview of typical inventions disclosed in this application is as follows.

In other words, the invention according to claim 1 provides that when forming a predetermined resist pattern on the surface of a semiconductor wafer, a second resist having a high dissolution inhibitor content is added to the surface of a first resist having a low dissolution inhibitor content. This is a method of manufacturing a semiconductor device by depositing.

The invention as set forth in claim 2 is a method of manufacturing a semiconductor device, in which a second resist is formed on the surface of the first resist by diffusing a dissolution inhibitor into the surface of the first resist.

Furthermore, the invention according to claim 3 provides a method for manufacturing a semiconductor device, in which a separation layer of a solvent type different from that of the first and second resists is interposed between the first resist and the second resist. be.

[Effect]

According to the invention described in claim 1, since the second resist can be deposited on the surface of the first resist with a uniform film thickness, the remaining film thickness on the resist surface in the unexposed area can be adjusted to the same thickness as that of the semiconductor wafer. It can be uniformly increased over the entire surface, and thereby the dimensional accuracy of the resist pattern can be improved with good yield.

Further, also according to the second aspect of the invention, in which a dissolution inhibitor is diffused onto the surface of the first resist, the second resist can be formed with a uniform thickness on the surface of the first resist.

Furthermore, according to the invention according to claim 3, a separation layer of a solvent system different from that of the first and second resists is interposed between the first resist and the second resist. It is possible to prevent the surface of the second resist from becoming rough due to the solvent contained therein, or from partially mixing the first resist and the second resist. It can be formed with a film thickness of

[Example 1] Figures 1(a) to (6) are sectional views of main parts of a semiconductor wafer showing a method for manufacturing a semiconductor device according to an embodiment of the present invention, and Figure 2 is a cross-sectional view of a main part of a semiconductor wafer used in this example. FIG. 2 is a graph diagram showing the relationship between resist development time and residual film thickness.

To explain the resist pattern forming process according to the first embodiment, first, as shown in FIG. 1(a), a semiconductor wafer 1 is
After depositing the first resist 2a on the surface, it is prebaked at a predetermined temperature. This semiconductor wafer 1 includes, for example, a 5102 film 4 formed on the surface of a semiconductor substrate 3 made of n-type or p-type silicon single crystal, and a film of, for example, Si, N, or Consisting of 5 and
The first resist 2a is uniformly deposited on the surface of the 513N4 film 5 using, for example, a spinner (not shown).

The first resist 2a is a positive resist made by mixing a base resin made of, for example, a novolac resin, a dissolution inhibitor made of naphthoquinone diazide, and an organic solvent. Depending on the situation, silane coupling treatment etc. are applied.

Next, as shown in FIG. 1(b), the first resist 2a is
After depositing the second resist (2b) on the surface, it is prebaked at a predetermined temperature. The second resist 2b, like the first resist 2a, is a positive resist made by mixing a base resin made of, for example, novolac resin, a dissolution inhibitor made of naphthoquinone diazide, and an organic solvent. 1) The content of the dissolution inhibitor was higher than that of 2a. The second resist 2b is uniformly deposited on the surface of the first resist 2a using, for example, a spinner.

Next, as shown in FIG. 1C, for example, an electron beam E is irradiated to expose only a predetermined region of the surface of the semiconductor wafer 1. Then, as shown in FIG. Then, in the area exposed to the electron beam E, a decomposition reaction of the dissolution inhibitor in the first resist 2a and the second resist 2b occurs.

Next, when the exposed semiconductor wafer 1 is immersed in a developer made of, for example, an alkaline aqueous solution, the second resist (2b) is first dissolved in the exposed area, and then the first resist (2a) underlying it is dissolved. dissolves. At this time, the first resist 1-2a with a lower content of dissolution inhibitor dissolves more quickly than the second resist 2b with a higher content of dissolution inhibitor.

On the other hand, in the unexposed portion of the second resist 2b, the base resin and the dissolution inhibitor are combined at a high concentration, so that the dissolution rate thereof is extremely slow. After this second resist 2b is dissolved, the first resist 2a underlying it is gradually dissolved. At this time, the first resist (2a) with a lower content of dissolution inhibitor dissolves more quickly than the second resist (2b) with a higher content of dissolution inhibitor, but the dissolution rate is lower than that of the first resist (2a) in the exposed area. The dissolution rate is much slower than that of Regis) 2a.

That is, according to the first embodiment, as shown in FIG.
It is possible to amplify the difference between the dissolution rate of resists) 2a and 2b in the exposed area and the dissolution rate of resists) 2a and 2b in the unexposed area, so that resists) 2a and 2b are completely dissolved in the exposed area. By setting the development time t such that the resist 2a remains to some extent in the unexposed area, the remaining film thickness of the resist 2a in the unexposed area can be increased. In FIG. 2, l and β2 indicate the film thickness of the first resist 2a and the second resist Bb, respectively.

As a result, as shown in FIG. 1(d), cysts 2a are formed at the ends of the unexposed areas, which are particularly susceptible to the effects of diffraction and sales companies.
Since film loss can be reduced, a resist pattern with high dimensional accuracy can be obtained.

In addition, since the second resist Bb is deposited with a uniform thickness on the surface of the first resist 2a at that time, the remaining film thickness on the surface of the resist 2a in the unexposed area is reduced over the entire surface of the semiconductor wafer l. This can be uniformly increased, thereby improving the yield of the resist pattern forming process.

In addition, in this Example 1, the first
2a with a high content of dissolution inhibitor.
However, the second resist 2b can be applied to the surface of the first resist 2a by diffusing the dissolution inhibitor onto the surface of the first resist 2a, which has a small content of dissolution inhibitor. It can be formed with a uniform thickness.

That is, for example, the first resist 2a is placed on the semiconductor wafer 1.
After applying the dissolution inhibitor diluted with an organic solvent to the surface of the first resist 2a and prebaking, the dissolution inhibitor is applied to the surface of the first resist 2a and prebaked again. is impregnated, so the first resist)2
A second resist 2b is formed with a uniform thickness on the surface of a.

[Embodiment 2] FIG. 3 is a sectional view of a main part of a semiconductor wafer showing a method for manufacturing a semiconductor device according to another embodiment of the present invention.

In Example 1, the second resist 2b having a high content of dissolution inhibitor was deposited on the surface of the first resist 2a having a low content of a dissolution inhibitor. Since the solvent and the organic solvent in the second resist 2b have the same or similar composition, for example, when prebaking the second resist 2b deposited on the surface of the first resist 2a, depending on the temperature conditions, , the surface of the first resist 2a may be roughened by the organic solvent in the second resist 2b,
Partial mixing of the first resist 2a and the second resist 2b may impair the uniformity of the resist film thickness.

Therefore, in the present Example 2, as shown in FIG. By interposing a separation layer 6 of a different solvent type from that of the resist 2a and the second resist 2b, the first resist 2a
This reliably prevents deterioration in the uniformity of the resist film thickness due to surface roughness and partial mixing of the first resist 2a and the second resist 2b.

The separation layer 6 of a solvent type different from that of the first resist 2a and the second resist 2b can be composed of, for example, a water-soluble polymer such as polyvinyl alcohol. Since such a water-soluble polymer is quickly dissolved in a developer such as an alkaline aqueous solution, there is no possibility that dissolution of the first resist 2a will be hindered in the development process.

Although the invention made by the present inventor has been specifically explained based on Examples above, the present invention is not limited to Examples 1 and 2, and can be modified in various ways without departing from the gist thereof. It goes without saying that there is.

For example, in Example 1.2, a novolac resin-based resist was used, but the present invention is not limited to this, and can be applied to any resist containing a dissolution inhibitor.

〔Effect of the invention〕

A brief explanation of the effects obtained by typical inventions disclosed in this application is as follows.

That is, when forming a predetermined resist pattern on the surface of a semiconductor wafer, the resist pattern is formed by depositing a second resist containing a high dissolution inhibitor content on the surface of a first resist containing a low dissolution inhibitor content. The dimensional accuracy of can be improved with good yield.

Furthermore, the dimensional accuracy of the resist pattern can be improved with good yield by forming a second resist on the surface of the first resist by diffusing a dissolution inhibitor on the surface of the first resist. .

Furthermore, the dimensional accuracy of the resist pattern can be improved with good yield by interposing a separation layer of a different solvent type than the first and second resists between the first resist and the second resist. be able to.

[Brief explanation of the drawing]

FIGS. 1(a) to (d) are cross-sectional views of main parts of a semiconductor wafer showing a method for manufacturing a semiconductor device according to an embodiment of the present invention. FIG. FIG. 3 is a graph showing the relationship with the remaining film thickness. FIG. 3 is a cross-sectional view of a main part of a semiconductor wafer showing a method for manufacturing a semiconductor device according to another embodiment of the present invention. FIG. FIG. 5 is a cross-sectional view of a main part of a semiconductor wafer schematically showing resist film reduction in the manufacturing method. FIG. 5 is a graph diagram showing the relationship between resist development time and remaining film thickness in a conventional semiconductor device manufacturing method. . l...Semiconductor wafer 2a...First resist, 2
b...Second resist, 3...Semiconductor substrate, film, 6...Si separation layer, film, 5...5isN<-resist. Figure 6: Separation layer diagram

Claims (1)

[Claims] 1. When forming a predetermined resist pattern on the surface of a semiconductor wafer using a resist containing a dissolution inhibitor, the dissolution inhibitor is added to the surface of the first resist containing a small amount of the dissolution inhibitor. A method for manufacturing a semiconductor device, comprising depositing a second resist having a high content. 2. By diffusing a dissolution inhibitor onto the surface of the first resist, the second resist is applied to the surface of the first resist.
2. The method of manufacturing a semiconductor device according to claim 1, wherein a resist is formed. 3. Manufacturing the semiconductor device according to claim 1, wherein a separation layer of a solvent type different from that of the first and second resists is interposed between the first resist and the second resist. Method.