JPH0481765A - Pattern forming method for chemical amplification type resist - Google Patents

Abstract

PURPOSE:To improve the shape of resist patterns by subjecting a chemical amplification type resist applied on a substrate to 1st exposing and bringing a chemical dye into selective reaction into the chemically activated part of a resist surface, then subjecting the entire surface to 2nd exposing. CONSTITUTION:The chemical amplification type resist 2A is applied on a semiconductor substrate 1 and is subjected to the 1st exposing by an ArF laser beam. The resist 2A is then immersed into a soln. prepd. by dissolving the chemical dye of an azo system into a solvent to fix the dye to the surface of the resist 2A. This chemical dye reacts with a phenolic hydroxyl group and fixes selectively to the 1st exposed parts 2a, thereby forming a dye mask 2b. A KrF laser beam has low transmittability to the dye mask 2b by the 2nd exposing and, therefore, the parts exclusive of the dye mask 2b are exposed and since the 2nd exposed parts are solubilized, these parts are removed by alkali development and the resist patterns 4 consisting of the dye mask 2b and the unexposed parts 2c thereunder are formed. The process is simplified in this way and since the fixing of the chemical dye is sure, the reproducibility of the patterns is good.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of patterning a chemically amplified resist used in a lithography process for semiconductor devices.

[Summary of the Invention] The present invention provides selective first exposure to a chemically amplified resist coated on a substrate to selectively expose the surface of the resist to
The shape of the resist pattern can be improved by chemically activating it and then selectively reacting the activated portions with a chemical dye, followed by a second overall exposure. This is what I did.

[Prior Art] In recent years, resists with high resolution have been actively developed, and a highly sensitive resist called a chemically amplified resist has been developed.

This chemically amplified resist utilizes a curing reaction or a decomposition reaction induced by an acid generated when an onium salt-based acid generator or the like is irradiated with light. In addition, the details of such chemically amplified resists include a base polymer made of cresol-based or polyhydroxylene-based resin, to which cross-linking agents and acid generators such as melamine-based derivatives (methylol derivatives) and polyhalides are added. Therefore, acid generated during exposure is reacted in a post-exposure bake (FEB) to solubilize the resist in positive type resists and insolubilize it in negative type resists.

3A to 3C show a method of forming a resist pattern using a positive chemically amplified renost.

In this method, first, as shown in FIG.
Apply a positive chemically amplified resist on top of O.

Next, as shown in FIG. 3B, a mask 1 of a predetermined pattern is
2 to selectively expose to light to form exposed portions 11a. At this time, acid is generated from the acid generator within the resist that has been irradiated with light. Next, post-exposure bake (FEB)
to cause a solubilization reaction with an acid. Furthermore, alkali development is performed to form a resist pattern Ilb as shown in FIG. 3C.

4A to 4C show a method of forming a resist pattern using a negative type chemically amplified resist.

In this method, first, as shown in FIG. 4A, a semiconductor substrate l.
After applying a negative type chemically amplified resist I3 on the resist 13, as shown in FIG. 4B, selective exposure is performed using a mask 14 having a predetermined pattern to form an exposed portion 13A.

At this time, acid is generated from the acid generator in the exposed portion 13A that is irradiated with light. Next, FEB is performed to cause a crosslinking reaction (insolubilization reaction) using Moeki acid. moreover,
Alkaline development is performed to form a resist pattern I5 (13A) as shown in FIG. 4C.

[Problems to be Solved by the Invention] However, in a pattern forming method using such a chemically amplified resist, when the chemically amplified resist is exposed to exposure light, for example, an ArF laser (193 nm), the light of the resist is Absorption was significant and it was difficult to obtain a well-shaped pattern.

That is, sufficient transmittance cannot be obtained in the chemically amplified resist, and therefore, as shown in FIGS. 3B and 4B,
The concentration distribution of the acid generated in the exposed areas 11a and 13A (indicated by dots in the middle of the figure) is high at the top and becomes low toward the bottom. If development is performed through FEB in such a state, the cross-sectional shape of the pattern becomes a chip< (or inverted Taber) shape, as shown in FIGS. 3C and 4C, resulting in a problem in which the pattern width varies. was there.

The present invention was devised by paying attention to such conventional problems, and aims to provide a pattern forming method for a chemically amplified resist that improves the shape of a resist pattern.

The dye is fixed by reaction. Then, by performing full-surface exposure in the second exposure, it becomes possible to selectively expose the chemically amplified resist using the dye fixing section as a mask. Therefore, it is possible to form a good pattern simply by providing a step of selectively fixing a chemical dye on the surface of a chemically amplified resist.

[Means for Solving the Problems] Therefore, the present invention provides selective first exposure to a chemically amplified resist coated on a substrate to selectively chemically activate the resist surface. Then, after selectively reacting the chemical dye to the activated part, the entire second
The solution is to apply exposure to light.

[Operation] The surface of the chemically amplified resist is selectively chemically activated by the first exposure. A chemical dye is selected on the surface portion of the activated resist [Example] Hereinafter, details of a method for forming a pattern of a chemically amplified resist according to the present invention will be explained based on an example shown in the drawings.

(First Example) FIGS. 1A to 1D show a first example in which the present invention is applied to a positive type chemically amplified resist.

The chemically amplified resist used in this example is made by adding an onium-based acid generator to a trimethylsilylphenol polymer represented by an alkaline compound with a protected phenolic OH group.

In this embodiment, first, as shown in FIG. 1A, a semiconductor substrate!
A chemically amplified resist 2A is applied thereon, and a first exposure is performed with ArF laser light (193 nm) using a mask 3. Due to this exposure, the protecting group is removed on the surface of the chemically amplified resist 2A by the acid catalyst generated by the photoreaction, and a phenolic hydroxyl group is generated. Note that 2a in the figure indicates the first exposure section.

Next, the chemically amplified resist 2A is immersed in a solution in which an azo chemical dye is dissolved in a relatively low polarity solvent, and the dye is fixed on the surface of the resist 2.

This chemical dye reacts with the phenolic hydroxyl group generated in the first exposure step, and is selectively fixed in the first exposure area 21 to form a dye mask 2b (FIG. 1B). In addition,
In addition to azo-based chemical dyes, for example, anthraquinone-based, phthalocyanine-based, and acidic dyes may be used, and the active groups (reactive functional groups) in these chemical dyes are, for example, dichlorotriazinyl, dichlorotriazinyl, trihalogen These include pyrimidine and dichloroquinoxaline.

Next, after passing through the water washing process, as shown in FIG.
A second exposure is performed on the entire surface with F laser light (248, 4 nm). Due to this second exposure, since the KrF laser beam has low transmittance to the dye mask 2b, parts other than the dye mask 2b are exposed, and a second
An exposed area is formed. This second exposed area is solubilized and removed by alkaline development to form a resist pattern 4 consisting of a dye mask 2b and an unexposed area 2c below it, as shown in the first diagram.

(Second Embodiment) FIGS. 2A to 2D illustrate a second embodiment of the present invention.

In this embodiment, a negative type chemically amplified resist is used, for example, a novolac resin with a crosslinking agent and an acid generator added thereto.

First, as shown in FIG. 2A, a chemically amplified resist 2B is applied to a semiconductor substrate 11, and a first exposure is performed using an ArF laser beam using a mask 3 to form a first exposed area (negative ) form 2d.

Next, as shown in FIG. 2B, the same chemical dye as in the first embodiment is fixed. In this embodiment, since the first exposed area 2d is negative, the chemical dye is fixed on the surface of the unexposed area, forming the dye mask 2e.

Next, as shown in FIG. 2C, the entire surface is exposed at once to KrF laser light (second exposure). At this time, K r F
As mentioned above, since the laser beam has low transmittance through the dye mask 2e, the dye mask 2e and the resist under it are removed by alkaline development, and as shown in the second diagram, the first exposed areas 2d and A resist pattern 5 is formed by the resist 2f below.

Although the first and second embodiments have been described above, the present invention is not limited to these.

For example, in both of the above embodiments, K r
Although F laser light was used, the entire surface may be exposed to deep UV light.

Furthermore, it is particularly desirable that the chemical dye has a long alkyl chain or the like and is soluble in a solvent with relatively low polarity.

[Effects of the Invention] As is clear from the above explanation, according to the method for forming a pattern of a chemically amplified resist according to the present invention, there is no need to arrange a separate resist layer on the chemically amplified resist, and the process is simple. Also, since the chemical dye is fixed firmly, pattern reproducibility is improved. Therefore, the pattern shape becomes good, and there is an effect that it is possible to cope with miniaturization of the pattern.

[Brief explanation of the drawing]

FIGS. 1A to 1D are process diagrams of the first embodiment (positive type) of the pattern forming method of a chemically amplified resist according to the present invention;
Figures 2A to 2D are process diagrams of the second embodiment, Figure 3A
- FIG. 4C is a process diagram of a conventional example. ■...Semiconductor substrate (substrate), 2A, 2B...Chemically amplified resist, 2b, 2e...Dye mask, 3...Mask, 4°5...Resist pattern. Fig. 3 A (I pot ★ ◆ Number pot pot ÷ article + row of rows (positive Mi) Fig. 3 B Ibumino P; Itari (Jgun type) ) Figure 3C

Claims (1)

[Claims] (1) A chemically amplified resist coated on a substrate is subjected to selective first exposure to selectively chemically activate the resist surface, and then the activated portion is chemically activated. A method for forming a chemically amplified resist pattern, which comprises selectively reacting a dye and then performing a second exposure over the entire surface.