JPH0792605B2 - Resist pattern formation method - Google Patents

Description

The present invention relates to a resist pattern forming method, and more particularly to a resist pattern forming method suitable for forming a resist pattern having a fine structure such as a semiconductor integrated circuit.

[Conventional technology]

FIGS. 3A to 3C are views showing a conventional resist pattern forming method.

As shown in FIG. 3A, a positive photoresist is applied on a substrate to be processed, for example, a semiconductor substrate (1) to form a resist layer (2).

Next, as shown in FIG. 3B, a resist layer (2) is passed through a photomask (3) having a pattern opposite to the predetermined pattern.
It is exposed to light (4) to expose it.

Next, the exposed resist layer (2) is developed with an alkali developing solution to expose the exposed portion (1) of the resist layer (2).
0) is removed. As a result, a predetermined resist pattern (6) is formed on the semiconductor substrate (1) as shown in FIG.

[Problems to be Solved by the Invention]

The conventional resist pattern forming method as described above is
There was a problem as explained in the figure.

As shown in FIG. 4A, light (4) is applied to the photoresist layer (2) on the semiconductor substrate (1) through the photomask (3). At this time, the light passing through the photomask (3) has a pattern corresponding to the pattern of the photomask (3). However, as the pattern becomes finer and out of focus, the light passing through the photomask (3) does not always follow the desired pattern due to the influence of stray light, light wraparound, etc. Light pattern) (5) appears. The exposed portion (7) of the resist layer (2) irradiated with light having such a deteriorated light pattern (5) is affected by the deteriorated light pattern (5) and is indicated by a line (8). It has such incident light distribution. By the way, the phenomenon of the exposed resist progresses substantially according to the incident light distribution of the exposed portion (7), but since the development is a chemical reaction originally, it does not necessarily follow the incident light distribution and deteriorates. The effect of the light pattern is somewhat improved. However, it is impossible to completely eliminate the influence of the deteriorated light pattern (5), and the influence remains on the resist pattern (6), resulting in a deteriorated pattern (9) as shown in FIG. 4 (b). .

Therefore, the conventional resist pattern forming method further deteriorates an optical image when forming an extremely fine resist pattern required for a highly integrated semiconductor integrated circuit which will be mass-produced in the near future. The resist pattern image is further deteriorated. There is a problem that such deterioration of the resist pattern image causes a dimensional variation of the resist pattern when etching is performed using this resist pattern.

The present invention solves the above-mentioned drawbacks of the conventional resist pattern forming method, can expose the resist pattern without reflecting the deterioration of the optical image in the resist pattern, and has a small dimensional variation. It is intended to provide a method of forming.

[Means for Solving the Problems]

The resist pattern forming method according to the present invention comprises the steps of forming a photoresist layer on a substrate, exposing the photoresist surface to water vapor, and exposing the resist layer to ultraviolet light through a photoresist mask in a gas atmosphere of a titanium alkoxy compound. A step of forming a hydroxide titanium compound layer by hydroxylating the titanium alkoxy compound using water vapor at a temperature in the range of room temperature to 200 ° C., and using the hydroxide titanium compound layer as a mask, for example, I line (365nm) to G line (436n) of mercury lamp
m) irradiating the entire surface of the resist layer to expose it,
Developing the resist layer exposed in this exposure step, and removing the remaining portion of the resist layer, which is exposed through the photomask.

[Action]

In the resist pattern forming method of the present invention, a patterned titanium compound film is formed on the resist surface by irradiating light through a photomask in a gas atmosphere of a titanium alkoxy compound. This titanium compound film is excellent in dry etching resistance and acts as a resist pattern with little dimensional variation.

〔Example〕

An embodiment of the present invention will be described in detail below with reference to FIGS. 1 and 2.

As shown in FIG. 1 (a), a highly sensitive photoresist is coated on a substrate (1) made of, for example, a semiconductor substrate,
Pre-bake at 80 ℃ for about 80 seconds to photoresist layer (2)
To form. For example, OFPR-800 manufactured by Tokyo Ohka Kogyo Co., Ltd. is used as the resist. Next, the surface of the photoresist is hydroxylated with steam of 0.01 to 100 Langmuir at a temperature of 20 ° C to 100 ° C.

Next, as shown in FIG. 1 (b), the focus state on the surface of the resist layer (2) is optimized in a tetra-isobutoxytitanium atmosphere (14) through a photomask (13) having a desired pattern. Exposure is performed using, for example, ultraviolet light (12) adjusted as described above. By this exposure treatment, the titanium compound is chemically bonded only to the hydroxyl groups on the photoresist surface of the exposed portion of the surface of the resist layer (2). Excess titanium compound is removed by evacuation.

Next, as shown in FIG. 1 (c), the titanium compound chemically bonded to the surface of the resist layer (2) in the step of FIG. 1 (b) is exposed to water vapor (15) to remove excess isobutoxy group. Is replaced with a hydroxyl group, and a titanium hydroxide compound layer (16) which acts as a mask is formed on the resist layer (2) in the next step. The temperature of the water vapor is not so critical and may be any temperature in the range of room temperature to about 200 ° C.

Next, as shown in FIG. 1 (d), the entire surface of the resist layer (2) on which the titanium hydroxide compound layer (16) is formed is exposed to light (17 lines) of 365 nm (I line) to 436 nm (G line) of a mercury lamp, for example. ). At this time, the titanium hydroxide compound layer (16) acts as a mask, and the portion (18) of the resist layer (2) not covered with the titanium hydroxide compound layer (16) is exposed.

Finally, the exposed portion (18) in FIG. 1 (d) is developed and removed to remove the substrate (1) as shown in FIG. 1 (e).
A desired resist pattern (19) is formed on it.

FIG. 2 is a view for explaining the step of FIG. 1 (b) in more detail.

When the resist layer (2) is irradiated with ultraviolet light (12) in a tetra-isobutoxytitanium atmosphere (14) through a photomask (13), as shown in FIG. The exposed tetra-isobutoxytitanium and the surface hydroxyl groups of the resist layer (2) are brought into an excited state.

The irradiated part (a) (20) in FIG. 2 (b) is an active excited species ((CH ₃ ) ₃ C of tetra-isobutoxytitanium.
O) ₄ Ti ^* , and (21) represents the excited species OH ^* of the surface hydroxyl group.
The part masked by the photo mask (13) (b)
The tetra-isobutoxytitanium and hydroxyl groups of are not excited.

Either one or both of the above-mentioned active excited species (20) and (21) act to cause tetra-
Isobutoxytitanium is immobilized by a compound bond,
As shown in FIG. 2 (c), tri-isobutoxytitanium surface species (22) are formed. The immobilization reaction as described above does not occur in the portion (b) where light is blocked by the photomask (13), and tetra-isobutoxytitanium merely physically adsorbs to the surface of the resist layer (2). Therefore, during vacuum evacuation, the tetra-isobutoxytitanium in the portion (b) is released and removed together with the residual gas. Due to such a difference in photochemical activity, a patterned titanium hydroxide compound layer is formed on the surface of the resist layer (2) as shown in FIG. 1 (c).

In the above examples, tetra-isobutoxytitanium was used as the titanium compound, but other alkoxytitaniums such as methoxytitanium, ethoxytitanium, n-propoxytitanium, isopropoxytitanium, or titanium halides such as titanium tetratitanium. Chlorides can also be used. Further, in the above-mentioned embodiment, the case where the patterned resist layer is formed on the semiconductor substrate has been described, but a printed board may be used as the board (1).

〔The invention's effect〕

As described above, according to the present invention, a mask is directly formed on the photoresist layer (2) with a thin film of a titanium hydroxide compound, and the photoresist layer is exposed using this mask. It is possible to form a resist pattern that is free from deterioration, has excellent dry etching resistance, and has little dimensional variation. Further, the method of the present invention does not need to consider the amount of change depending on the resist film thickness, and achieves high integration. Especially suitable for forming precise fine patterns suitable for

[Brief description of drawings]

FIG. 1 is a diagram for explaining each step of an embodiment of a resist pattern forming method according to the present invention, FIG. 2 is a diagram for explaining a part of the steps of FIG. FIG. 4 is a diagram for explaining a resist pattern forming method, and FIG. 4 is a diagram for explaining a defect in forming a resist pattern by the conventional resist pattern forming method shown in FIG. (1) ... Substrate, (2) ... Photoresist layer, (13)
...... Photo mask, (14) …… Gas atmosphere of titanium alkoxy compound, (15) …… Water vapor, (16) …… Hydroxide titanium compound layer, (18) …… Covered with titanium hydroxide layer mask Resist layer other than the
9) ... desired resist pattern.

Claims (1)

[Claims] 1. A step of forming a photoresist layer on a substrate, a step of exposing the photoresist surface to water vapor, a step of exposing the photoresist layer through a photomask in a gas atmosphere of a titanium alkoxy compound, and a step of exposing the photoresist layer to water vapor. Hydroxizing a titanium alkoxy compound to form a hydroxylated titanium compound layer having a desired pattern on the surface of the photoresist layer, and exposing the resist layer to the entire surface by using the hydroxylated titanium compound layer as a mask. And a step of developing the resist layer exposed in the exposing step to remove the resist layer other than the masked portion of the titanium compound layer to form a desired resist pattern on the substrate. A method of forming a resist pattern including.