JP2611215B2 - Pattern formation method - Google Patents

Description

The present invention relates to a method for forming a pattern on an object to be etched by photolithography and etching.

[Summary of the Invention]

According to the present invention, in the pattern forming method as described above, an antireflection film containing an acrylic resin is formed on an object to be etched, and then photolithography is performed to etch the antireflection film and the object to be etched at once. By
This is to enable high-precision pattern formation with a simple process.

[Conventional technology]

A fine pattern such as a wiring of a semiconductor device is formed by photolithography and etching. However,
If an attempt is made to form a wiring or the like with a material having a high reflectance such as Al, in photolithography, halation occurs in the photoresist layer due to reflection by Al. Therefore, in such a case, a highly accurate pattern cannot be formed.

For this reason, the applicant uses an anti-reflection film and retains the anti-reflection film when developing the photoresist layer in order to prevent the anti-reflection film from being separated from the photoresist layer due to undercut of the anti-reflection film. A pattern forming method that has been proposed has already been proposed as Japanese Patent Application No. 60-201752.

[Problems to be solved by the invention]

However, in the above-mentioned prior application, the antireflection film is formed by ARC (trade name of Brewer Science) in which a dye that absorbs light is added to a polyimide resin. And this ARC,
It is inherently soluble in an alkaline developer, which is a developer for the photoresist layer.

For this reason, in the above-mentioned prior application, the ARC is made insoluble in the developing solution of the photoresist layer by baking the ARC under specific conditions. However, adjustment of firing conditions is not easy, and the above-mentioned prior application cannot form a pattern by a simple process.

ARC has relatively high etching resistance. For this reason, if the ARC and Al or the like are to be etched at a time while the ARC is left during the development of the photoresist layer, the photoresist layer retreats considerably before the etching of the Al or the like is started. Therefore, in the above-described embodiment, it is not possible to form a high-precision pattern by transferring the pattern formed on the photoresist layer as it is to the object to be etched.

[Means for solving the problem]

The pattern forming method according to the present invention includes a step of forming an antireflection film 13 containing an acrylic resin on the workpiece 12, a step of forming a photoresist layer 14 on the antireflection film 13, and a step of forming the photoresist layer. Exposing and developing 14 to form a pattern on this photoresist layer 14,
The anti-reflection film 13 and the object to be etched 12 are selectively and temporarily etched by using the photoresist layer 14 having the pattern formed thereon as a mask.
And a step of forming a pattern.

[Action]

In the pattern forming method according to the present invention, the antireflection film 13 containing an acrylic resin is used.
Is insoluble in an alkali developing solution which is a developing solution for the photoresist layer 14.

Therefore, in order to prevent the antireflection film 13 and the photoresist layer 14 from peeling off due to the undercut of the antireflection film 13 and the like, when the antireflection film 13 is left during the development of the photoresist layer 14, it depends on specific conditions. No baking or the like is required.

Further, the anti-reflection film 13 containing an acrylic resin has a low etching resistance of about 1/2 to 1/3 as compared with, for example, an anti-reflection film containing a polyimide resin.

Therefore, when the photoresist layer 14 is developed,
The anti-reflection film 13 and the object to be etched
Even if the substrate 12 is etched at one time, the retreat amount of the photoresist layer 14 until the etching of the etching target 12 is started is sufficiently small. Therefore, the pattern formed on the photoresist layer 14 is directly etched. Is transferred to object 12.

〔Example〕

Hereinafter, an embodiment of the present invention applied to the formation of Al wiring of a semiconductor device will be described with reference to FIG.

First, as shown in FIG. 1A, a semiconductor substrate 11 made of Si or the like is used.
An Al layer 12 to be etched is formed thereon.

Next, as shown in FIG. 1B, the PMMA added with a dye that absorbs light used in photolithography (such as the G and I rays of a mercury lamp) is spin-coated on the Al layer 12 and baked to form a film as shown in FIG. An antireflection film 13 having a thickness of about 2000 mm is formed.

A sufficient amount of dye is added to PMMA so that the antireflection film 13 has a sufficient antireflection function. Note that PM
As the MA, for example, OEBR-1000 (trade name of Tokyo Ohka Kogyo) can be used.

Next, as shown in FIG. 1C, a positive photoresist is spin-coated on the anti-reflection film 13 to form a film having a thickness of 1-2.
A photoresist layer 14 of about μm is formed. As the positive photoresist, for example, OFPR-800 (trade name of Tokyo Ohka Kogyo) can be used.

Next, as shown in FIG. 1D, the photoresist layer 14 is exposed using a mask 15, and the photoresist layer 14 is further developed.

Incidentally, the anti-reflection film 13 formed by adding a dye to PMMA is insoluble in an alkali developing solution which is a developing solution for the photoresist layer 14. For this reason, in the above-mentioned development, as shown in FIG. 1E, a pattern is formed only on the photoresist layer 14, and the antireflection film 13 remains as it is.

Next, as shown in FIG. 1F, RIE using a chlorine-based ion gas 16 is performed using the photoresist layer 14 as a mask.

However, the anti-reflection film 13 has extremely low etching resistance as compared with the photoresist layer 14, and has a smaller thickness than the photoresist layer 14. For this reason, in the above-mentioned RIE, the first
The selective etching of the antireflection film 13 as shown in FIG. G is performed in a short time, and subsequently, the Al layer 12 as shown in FIG.
Is selectively etched.

For this reason, even if the antireflection film 13 and the Al layer 12 are etched at once, the amount of retreat of the photoresist layer 14 until the etching of the Al layer 12 is started is sufficiently small. Therefore,
The pattern formed on the photoresist layer 14 in the step of FIG. 1E is directly transferred to the Al layer 12 in the steps of FIGS. 1F to 1H.

Next, as shown in FIG. 1H, the photoresist layer 14 and the antireflection film 13 are ashed and removed using an oxygen plasma 17 or the like. Then, as shown in FIG. 1I, a semiconductor device having a wiring pattern formed on the Al layer 12 is obtained.

In the above embodiment, the antireflection film 13 is formed by adding a dye to PMMA. However, the antireflection film 13 may be formed by adding a dye to an acrylic resin other than PMMA.

〔The invention's effect〕

In the pattern forming method according to the present invention, baking or the like under specific conditions is not required, and the antireflection film and the object to be etched are etched at a time, so that the pattern can be formed in a simple process.

Even if the anti-reflection film and the object to be etched are etched at one time, the pattern formed on the photoresist layer is transferred to the object to be etched as it is. It can be performed.

[Brief description of the drawings]

 FIG. 1 is a side view sequentially showing one embodiment of the present invention. In the reference numerals used in the drawings, 12 ... Al layer 13 ... antireflection film 14 ... photoresist layer.

Claims (1)

(57) [Claims] A step of forming an anti-reflection film containing an acrylic resin on an object to be etched; a step of forming a photoresist layer on the anti-reflection film; exposing and developing the photoresist layer; Forming a pattern on a photoresist layer, and selectively and temporarily etching the antireflection film and the workpiece using the photoresist layer on which the pattern is formed as a mask to form a pattern on the workpiece. And a forming step.