JP3063745B2 - Processing method of patterned resist film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating a patterned resist film, and more particularly to a method for treating a patterned resist film in which the pattern shape is prevented from changing even at a high temperature. Things.

[0002]

2. Description of the Related Art With the recent high integration of semiconductor integrated circuits (LSI), it is required to form a high-resolution resist pattern, and accordingly, high sensitivity, high resolution and dry etching resistance are required. There is a demand for a resist material that is excellent. Novolac resin-based photoresists, which are widely used at present, have a light transmittance as the light from an exposure light source becomes shorter in wavelength from i-ray (wavelength 365 nm) to KrF excimer laser light (wavelength 248 nm). Disadvantages arise, making it difficult to use. For this reason, a chemically amplified resist utilizing a catalytic reaction (chemically amplified resist) has attracted attention, and application to a process is being studied earnestly. Further, the chemically amplified resist is promising as a resist material for lithography such as electron beams and X-rays as well as far ultraviolet rays. Hereinafter, a conventional method of forming a resist pattern will be described with reference to the accompanying drawings.

FIGS. 2 and 3 show the reaction formulas of a typical chemically amplified positive resist, respectively. As shown in FIG. 2, an acid is generated from an acid generator (PAG) by exposure.
As shown in FIG. 3, this acid acts as a catalyst when heat (△ in FIG. 3) is given, and tertiary butoxycarbonyl (t-BOC: t-butox) which is a dissolution inhibitor is used.
(ycarbonyl) group. The generated polyhydroxystyrene is dissolved in an alkali developer, so that a positive resist pattern can be obtained. With the advent of this chemically amplified resist, for example,
A resist pattern having high resolution, high sensitivity, and a rectangular resist shape can be obtained even by patterning using a KrF excimer laser beam. Hereinafter, using FIG.
By way of example, a conventional resist pattern forming method using such a chemically amplified positive resist will be described.

FIGS. 4 (a) and 4 (b) are cross-sectional views of a substrate in respective steps showing a conventional method for forming a resist pattern. Conventionally, first, hexamethyldisilazane (HMD)
The semiconductor substrate 1 is formed by a silane coupling agent such as S).
0 (hereinafter simply referred to as the substrate 10). Subsequently, a chemically amplified positive resist comprising a PHS (polyhydroxystyrene) resin, an acid generator and a dissolution inhibitor is applied on the substrate 10 by using a spin coating method. PHS
The resin has a t-BOC (tertiary butoxycarbonyl) group or an acetal-based dissolution inhibiting group having a content of 40% to 6%.
It is a resin protected by about 0%. Next, prebaking is performed at 90 ° C. to 110 ° C., and the film thickness t is 0.7 μm.
A resist film 11 having a thickness of about m to 1.0 μm is formed (see FIG. 4A).

Next, exposure is performed using an exposure apparatus that emits light such as ultraviolet rays, electron beams or X-rays 12, and heat energy is given by performing post-exposure bake (PEB) at a temperature between 90 ° C. and 120 ° C. The acid generated in the resist film by the exposure is reacted as a catalyst. Next, an aqueous solution of an organic alkali, for example, a 2.38 wt% aqueous solution of tetramethylammonium hydroxide (TMAH) is applied as a developing solution on the substrate, and is developed for 60 to 120 seconds, followed by rinsing and drying. By doing so, FIG.
As shown in (b), a patterned resist film (hereinafter referred to as a resist pattern film) 11A is formed.

[0006]

Incidentally, it is known that the heat resistance of a chemically amplified resist is generally lower than the heat resistance of a base resin constituting the resist. Specifically, the heat resistant temperature of the base resin is from 150 ° C. to 170 ° C.
Although it is close, the heat resistance temperature of the resist is from 100 ° C to 1
Only about 10 ° C. For this reason, the following problems have occurred. First, the temperature of the final step of lithography for sintering the resist pattern film, that is, the post-bake temperature must be 110 ° C. or less. If post-baking is performed at a temperature higher than this, the resist pattern film undergoes a shape change such as heat dripping due to insufficient heat resistance, and the rectangular shape cannot be maintained. Second, in the subsequent steps such as dry etching and ion implantation, the processing temperature may be 100 ° C. or higher. At this time, the resist pattern film undergoes a shape change due to heat, and the pattern before and after the etching. Are different. That is, even if a resist pattern is formed with high precision by lithography, the resist pattern is not effectively reflected on an actual device pattern, and a device failure occurs.

It has been reported that the cause of the low heat resistance of the chemically amplified resist is a dissolution inhibitor protecting the resin. In order to improve this, after forming a resist pattern, irradiation with far ultraviolet rays is performed to decompose the dissolution inhibitor and remove P
UV cure has been proposed to increase heat resistance by converting to HS. FIGS. 5A and 5B respectively show this UV
FIG. 5 is a cross-sectional view of the substrate in each step when curing is performed on the substrate illustrated in FIG. However, in this method, the dissolution reaction of the dissolution inhibitor occurs inside the resist pattern film due to the high transmittance of the deep ultraviolet ray of the resist, and the resist pattern undergoes significant shape deterioration due to the reduction in the volume of the resist,
As a result, another problem of dimensional variation of the pattern occurs. For example, far ultraviolet rays 18 are applied to the resist pattern film 11A.
(See FIG. 5 (a)).
In (b), the upper width B ′ is significantly smaller than the lower width B.

In view of the circumstances described above, an object of the present invention is to provide a method for treating a patterned resist film, which suppresses a change in pattern shape even at a high temperature.

[0009]

Means for Solving the Problems As a result of intensive studies, the present inventors cured the surface layer, that is, the upper layer and the side layer of the resist pattern film, and further cured the surface layer, that is, the upper layer and the side layer of the resist pattern film among the dissolution inhibitors. The inventors have found a method of thermally decomposing only the dissolution inhibitor contained in the present invention, and have completed the present invention.

In order to achieve the above object, a method for treating a patterned resist film according to the present invention comprises a chemically amplified resist containing a dissolution inhibitor, and forms a film on a substrate and further forms a pattern. A method of treating a resist film (hereinafter, referred to as a resist pattern film), in which a water-soluble cross-linking agent is applied to the resist pattern film and brought into contact for a predetermined time to apply the water-soluble cross-linking agent to the upper layer and the side layer of the resist pattern film. Infiltrating and further removing the remaining water-soluble cross-linking agent by washing with water, and heat-treating the substrate under the first predetermined condition to cause a thermal cross-linking reaction between the penetrated water-soluble cross-linking agent and the resist pattern film. To cure the upper layer and the side layer of the resist pattern film (thermal crosslinking reaction step);
Heat treating the substrate under a second predetermined condition higher in temperature than the first predetermined condition to thermally decompose the dissolution inhibitor contained in the upper layer and the side layer of the resist pattern film (pyrolysis step). It is characterized by:

In the present invention, the etching resistance is improved by the thermal crosslinking reaction step, and the heat resistance is improved by the thermal decomposition step. This makes it possible to increase the etching selectivity between the resist pattern film and a wiring material such as aluminum, and when performing high-temperature processing such as dry etching or ion implantation in the next step, the shape of the resist pattern due to heat dripping or the like. Deterioration can be suppressed. Therefore, a good device pattern shape can be obtained. Also, since the resist film can be made thinner,
A finer resist pattern can be formed.

The water-soluble crosslinking agent contains an epoxy compound as one example, and contains hexamethylolmelamine as another example. The chemically amplified resist comprises, for example, a polyhydroxystyrene resin, an acid generator that generates an acid upon irradiation with ultraviolet rays, and a dissolution inhibitor.

The predetermined time for bringing the water-soluble crosslinking agent into contact with the resist pattern film is usually in the range of 60 seconds to 120 seconds. Preferably, the first predetermined condition is that the heat treatment temperature is 9
In the range of 0 ° C to 110 ° C, the heat treatment time is 30 seconds to 1
Within the range of 20 seconds. Thereby, the thermal crosslinking reaction step can be favorably performed. Preferably, the second predetermined condition is that the heat treatment temperature is in a range of 135 ° C. to 150 ° C., and the heat treatment time is in a range of 10 seconds to 20 seconds. Thereby, the thermal decomposition step can be performed favorably.

[0014]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Embodiment 1 Embodiment 1 is an embodiment of the present invention. FIG.
FIGS. 3A to 3F are cross-sectional views of a substrate for each step in a method for processing a patterned resist film performed in the present embodiment. In the present embodiment, first, P
Using a chemically amplified positive resist composed of an HS resin, an acid generator and a dissolution inhibitor, the resist film 11 was formed to a thickness of 0.7 μm.
Is formed on the substrate 10 so as to have a film thickness t of about 1.0 μm (see FIG. 1A).
Rinsing and drying are performed to form a resist pattern film 11A as shown in FIG.

Next, a water-soluble cross-linking agent 13 using an epoxy compound is put on the substrate, and the substrate is allowed to stand still for 60 to 120 seconds. Thereby, as shown by the arrow 14 in FIG. 1C, the water-soluble crosslinking agent penetrates into the surface layer of the resist pattern film 11A, that is, the upper layer and the side layer. Further, the substrate is placed in a heater (hot plate) 15 for 60 seconds at a processing temperature of 90 ° C. to 100 ° C. to perform a first heat treatment (see FIG. 1D). As a result, a thermal crosslinking reaction occurs in the base resin contained in the surface layer of the resist pattern film 11A due to the penetrated water-soluble cross-linking agent and thermal energy given from the heater, and the surface layer is hardened and has a high etching resistance. It becomes the crosslinked layer 16.

Next, the processing temperature is changed from 135 ° C. to 150 ° C.
, And a second heat treatment is similarly performed using the heater (hot plate) 15. The processing time at this time is 15 seconds or less. As a result, of the dissolution inhibitors that protect the resin constituting the resist pattern film 11A, only the dissolution inhibitor contained in the surface layer of the resist pattern film 11A is thermally decomposed, that is, the t-BOC group is thermally decomposed. Thus, a layer 17 having high etching resistance and high heat resistance is formed outside (see FIG. 1E). The substrate (see FIG. 1 (f)) taken out of the heater 15 can be treated with the layer 17 even if plasma etching or ion implantation is performed using this resist pattern film as a mask.
Width B of ₁ does not change before and after treatment, does not occur deterioration in shape of the resist pattern film by heat sagging like. Therefore,
Good device patterns can be obtained.

Embodiment 2 In this embodiment, a resist film made of a chemically amplified positive resist is formed in the same manner as in Embodiment 1, followed by exposure, development, rinsing and drying. A resist pattern film is formed. Next, a water-soluble crosslinking agent using hexamethylol melamine was placed on the semiconductor substrate, and
The semiconductor substrate is allowed to stand still for seconds to 120 seconds. Thereafter, using a heater (hot plate), the treatment temperature is set to 10
The first heat treatment is performed at 0 ° C. for a treatment time of 60 seconds. As a result, a thermal crosslinking reaction occurs due to the water-soluble crosslinking agent penetrating into the surface layer of the resist pattern film and the thermal energy given from the heater. Thus, the surface layer of the resist pattern film can be cured by crosslinking the base resin.
Next, a second heat treatment is similarly performed using a heater (hot plate) at a treatment temperature of 135 ° C. to 150 ° C.
The processing time at this time is 15 seconds or less. Thereby, only the dissolution inhibitor contained in the surface layer of the resist pattern film among the dissolution inhibitors protecting the resin constituting the resist pattern film is thermally decomposed, that is, the t-BOC group is thermally decomposed. Thus, similarly to the first embodiment, a layer having high etching resistance and high heat resistance is formed on the outside. Thereafter, even if plasma etching or ion implantation is performed using this resist pattern film as a mask, the resist pattern film does not undergo shape deterioration such as heat dripping, and therefore, a good device pattern can be obtained.

[0018]

According to the present invention, a step of infiltrating a water-soluble cross-linking agent into an upper layer and a side layer of a resist pattern film, and causing a thermal cross-linking reaction between the penetrated water-soluble cross-linking agent and the resist pattern film, The method includes a step of curing an upper layer and a side layer of the resist pattern film, and a step of thermally decomposing a dissolution inhibitor contained in the upper layer and the side layer of the resist pattern film. Thereby, the etching resistance and the heat resistance of the upper layer and the side layer of the resist pattern film can be improved.
Therefore, the etch rate of the resist pattern film can be reduced, and the etching selectivity with respect to a wiring material such as aluminum can be increased. In addition, when performing a high-temperature treatment such as dry etching or ion implantation thereafter, it is possible to suppress the occurrence of heat dripping in the resist pattern film, so that a good device pattern shape can be obtained. Further, since the thickness of the resist film can be reduced, a finer resist pattern can be formed.

[Brief description of the drawings]

FIGS. 1A to 1F are cross-sectional views of a substrate for each process in a method for processing a patterned resist film performed in a first embodiment.

FIG. 2 is a reaction formula of a chemically amplified positive resist.

FIG. 3 is a reaction formula of a chemically amplified positive resist.

FIGS. 4A and 4B are cross-sectional views of a substrate in respective steps showing a conventional method for forming a resist pattern.

FIGS. 5 (a) and 5 (b) respectively show a conventional U
FIG. 5 is a cross-sectional view of the substrate in each step when V curing is performed on the substrate illustrated in FIG.

[Explanation of symbols]

 Reference Signs List 10 semiconductor substrate (substrate) 11 resist film 11A resist pattern film 12 ultraviolet ray or electron beam or X-ray 13 water-soluble crosslinking agent 14 arrow 15 heater (hot plate) 16 thermal crosslinking layer 17 layer 18 far ultraviolet ray 20 heat resistant film

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI H01L 21/30 571

Claims (8)

(57) [Claims] 1. A method of treating a resist pattern film formed of a chemically amplified resist containing a dissolution inhibitor and formed on a substrate and further patterned, wherein a resist pattern film is formed on an upper layer and a side layer of the resist pattern film. A method for treating a patterned resist film, comprising a step of thermally decomposing only a contained dissolution inhibitor. 2. A method for treating a resist pattern film formed of a chemically amplified resist containing a dissolution inhibitor and formed on a substrate and further patterned, wherein a water-soluble crosslinking agent is added to the resist pattern film. Coating and contacting for a predetermined time to allow the water-soluble cross-linking agent to penetrate into the upper layer and the side layer of the resist pattern film, and further to remove the remaining water-soluble cross-linking agent by washing with water; Heat-treating the substrate to cause a thermal cross-linking reaction between the penetrated water-soluble cross-linking agent and the resist pattern film, thereby curing the upper layer and the side layer of the resist pattern film; Heat-treating the substrate under the second predetermined condition having a high temperature to thermally decompose only the dissolution inhibitor contained in the upper layer and the side layer of the resist pattern film. A method for treating a patterned resist film. 3. The method for treating a patterned resist film according to claim 2, wherein the water-soluble crosslinking agent contains an epoxy compound. 4. The method for treating a patterned resist film according to claim 2, wherein the water-soluble crosslinking agent contains hexamethylolmelamine. 5. The method for treating a patterned resist film according to claim 2, wherein the predetermined time for bringing the water-soluble crosslinking agent into contact with the resist pattern film is within a range of 60 seconds to 120 seconds. . 6. The first predetermined condition is that the heat treatment temperature is 90 ° C.
To 110 ° C, heat treatment time from 30 seconds to 120
The method for treating a patterned resist film according to claim 2, wherein the time is within seconds. 7. The second predetermined condition is that the heat treatment temperature is 135.
C. to 150 ° C., heat treatment time 10 seconds to 20
The method for treating a patterned resist film according to claim 2, wherein the time is within seconds. 8. The pattern formation according to claim 1, wherein the chemically amplified resist comprises a polyhydroxystyrene resin, an acid generator that generates an acid upon irradiation with ultraviolet rays, and a dissolution inhibitor. Processing method for the resist film thus obtained.