JPH0844070A - Method for manufacturing semiconductor device - Google Patents

Abstract

(57) [Summary] [Object] The present invention provides a method for forming a resist pattern at a level of sub-quarter micron or less using a chemically amplified resist so that the cross-sectional shape of the resist pattern can be formed vertically. The most main feature. [Structure] For example, a chemically amplified positive type resist 12 is applied onto a substrate 11, and a laser beam 13 having energy not reaching an exposure threshold level is applied to the substrate 11 to expose the entire surface. Then, after the elimination reaction of the proton H ⁺ that occurs near the interface between the resist 12 and the substrate 11 is terminated, a chemically amplified positive type resist 14 is further applied, and the electron beam 15 is applied to this to apply a desired resist. Expose the pattern. Thereby, the resist opening 1 after development
It is configured to avoid the occurrence of the trailing phenomenon at the bottom of No. 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device, for example, and is particularly used for forming a resist pattern at a level of sub-quarter micron or less using a chemically amplified resist.

[0002]

2. Description of the Related Art Recently, a chemically amplified resist composed of a three-component system of a resin, an acid generator and a solvent has been used for forming a resist pattern at a level of sub-quarter micron or less. The formation of the pattern using the chemically amplified resist is, for example, coating the resist on the substrate, baking, exposing the desired pattern with light such as an electron beam,
It is performed by a plurality of steps including post-exposure bake and development.

That is, as shown in FIG. 3, this method is applied to a substrate 1 such as a GaAs substrate or a carbon film substrate.
A desired pattern is exposed by irradiating light such as an electron beam 3 on the chemically amplified resist 2 coated and baked on the above. Then, by the exposure, the proton H ⁺ generated from the acid generator in the resist 2 is diffused and amplified, further baked, and then developed using an alkali developing solution. This makes it possible to form a resist pattern at a level of sub-quarter micron or less.

However, in the conventional pattern formation using the chemically amplified resist 2 described above, when the pattern is formed on the substrate 1, the exposure region 4 is exposed by exposing it with the electron beam 3 or the like. As a result, the phenomenon that the proton H ⁺ generated from the acid generator in the resist 2 disappears near the interface between the resist 2 and the substrate 1.
It is considered that this is because a basic substance such as ammonia in the air attached to the surface of the substrate 1 reacts with the proton H ⁺ .

Therefore, in the case of a positive type resist having an opening for irradiation with the electron beam 3 or the like, the resist 2 at the portion where the proton H ⁺ has disappeared remains without being removed by the development and remains at the bottom of the resist opening 5. At 6 the resist 2 has a skirted shape (see FIG. 7C).

[0006] Conversely, in the case of a negative resist for exposing the non-irradiated portions of the electron beam 3, protons H ⁺ diffusion, the resist 2 by amplification becomes alkali-insoluble (negative resist loss of protons H ⁺ Since the developed portion is removed by the development), for example, as shown in FIG. 4, the resist 2 has a shape in which the bottom portion 8 of the resist opening 7 bites.

As described above, in the conventional method, the resist pattern cannot be formed to have a vertical cross-sectional shape, and is formed by, for example, the resist opening 5 and etching in the next step. There is a problem that a large pattern size conversion difference (ab) is caused between the opening 9 and the opening 9.

[0008]

As described above, conventionally, it is difficult to form the resist pattern so that the cross-sectional shape of the resist pattern becomes vertical, so that the pattern size conversion difference due to etching in the next step becomes large. There was such a problem.

Therefore, an object of the present invention is to provide a method of manufacturing a semiconductor device in which a resist pattern can be formed so that its cross-sectional shape is vertical and the difference in pattern dimension conversion in the next step can be suppressed to a small value. I am trying.

[0010]

In order to achieve the above object, in a method of manufacturing a semiconductor device according to the present invention, a substrate is coated with a first chemically amplified resist containing a first solvent. Then, after baking, the first step of exposing the entire surface with ultraviolet light having energy below the exposure threshold level,
A second chemically amplified resist containing a second solvent different in solvent from the first resist is applied onto the first resist, and after baking, a desired pattern is exposed by an electron beam. And a third step of developing the first and second chemically amplified resists.

Further, in the method of manufacturing a semiconductor device of the present invention, the first chemistry comprising a resin, an acid generator and a solvent which is one of ethyl lactate and MMP thinner on the substrate is composed of a three-component system. After applying an amplification type positive resist and baking, the entire surface is exposed with ultraviolet light having a wavelength of 250 nm or less and energy below the exposure threshold level,
The step of further baking, and a second chemical amplification type positive resist consisting of a three-component system in which the resin, the acid generator and the solvent are either ethyl lactate or MMP thinner, on the first resist. After baking, a step of irradiating an electron beam to expose a desired pattern and further baking,
Developing the first and second chemically amplified positive resists,
And a step of opening the electron beam irradiation portion substantially vertically.

Further, in the method of manufacturing a semiconductor device of the present invention, the first chemistry consisting of a three-component system in which the resin, the acid generator and the solvent are either ethyl lactate or MMP thinner on the substrate. After applying an amplification type negative resist and baking, exposing the entire surface with ultraviolet light having a wavelength of 250 nm or less and energy less than the exposure threshold level, and further baking, and a resin on the first resist. , A second chemically amplified negative resist consisting of a three-component system in which the acid generator and solvent are either ethyl lactate or MMP thinner, and after baking, electron beam irradiation is performed to expose the desired pattern. And a further step of baking, and a step of developing the first and second chemically amplified negative type resists and opening substantially vertically while leaving the electron beam irradiation portion. That.

[0013]

According to the present invention, when the resist pattern is formed on the substrate by the above-mentioned means so as to eliminate the proton H ⁺ that contributes to the photosensitivity of the chemically amplified resist, the proton H ⁺ between the resist and the substrate is formed. It is possible to prevent the occurrence of the trailing phenomenon (positive type resist) and the biting phenomenon (negative type resist) at the bottom of the resist opening after development. is there.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a method for forming a pattern using a chemically amplified positive resist according to the present invention.

First, for example, a chemically amplified resist (first chemically amplified resist) 12 having a film thickness of 100 nm is applied onto a substrate 11 such as a GaAs substrate or a carbon film substrate. As the chemically amplified resist 12, for example, a three-component chemically amplified positive resist composed of a resin, an acid generator and a solvent (first solvent), wherein the solvent is ethyl lactate is used.

The chemically amplified positive type resist 12 is baked at, for example, 100 ° C. for about 90 seconds (the above (a) in the figure). Then, the entire surface of the chemically amplified positive type resist 12 is irradiated with a laser beam 13 from, for example, a KγF excimer laser stepper (not shown) and uniformly exposed. At this time, the energy at which the resist 12 does not reach the exposure threshold level, for example, 5
Exposure is performed with an energy of 0 mJ / cm ² .

That is, the chemically amplified positive type resist 12
Is exposed by the amount of laser light that is not developed by the subsequent development processing. Then, after this exposure, the chemically amplified positive resist 12 is further heated to about 9 ° C. at about 9 ° C., for example.
It is baked for 0 seconds (above, the same figure (b)).

At this time, the proton H ⁺ generated from the acid generator in the chemically amplified positive resist 12 by the above exposure.
In most of the cases, the phenomenon of disappearance occurs between the substrate 11 and the resist 12.

Subsequently, the chemically amplified positive type resist 1 described above is used.
A chemically amplified positive resist (second chemically amplified resist) 14 consisting of a three-component system, which is the same as the resist 12 except that the solvent is MMP thinner, is applied on the second layer 2 in a thickness of 200 nm. It

The chemically amplified positive type resist 14 is baked at, for example, 100 ° C. for about 90 seconds (the above (c) in the figure). After this, a chemically amplified positive resist 14
Then, for example, a spot beam type electron beam (beam current 100 pA, 0.2 nC / cm) 15 is irradiated to expose a desired resist pattern.

After this exposure, the chemically amplified positive type resist 14 is further baked at 90 ° C. for about 90 seconds (the above (d) in the figure). And finally,
For example, development is performed for about 1 minute using an alkaline developer having a concentration of 0.14N and a liquid temperature of 23 ° C. As a result,
The resist openings 14 are formed by the resists 12 and 14 in the exposure region 16 irradiated with the electron beam 15 being dissolved into the developing solution (FIG. 8E). The resist opening 17 is opened slightly larger than the exposed region 16 by the diffusion and amplification effect of the proton H ⁺ .

In this case, the disappearance reaction of the proton H ⁺ generated in the resist 12 near the interface between the resist 12 and the substrate 11 has already been completed. For this reason,
In the pattern formation, in the exposed region 16 irradiated with the electron beam 15, the disappearance reaction of the proton H ⁺ generated from the acid generator in the resist 14 does not occur.

That is, the chemically amplified positive type resist 12
Due to the reaction with the proton H ⁺ generated from the acid generator in the resist 12 due to the entire surface exposure to, the basic substance near the interface between the resist 12 and the substrate 11 no longer exists. Therefore, in the vicinity of the interface with the substrate 11, the proton H ⁺ generated from the acid generator in the resist 14 is not lost by the reaction with the basic substance. Therefore, the resists 12 and 14 in the exposure region 16 which is the irradiation portion of the electron beam 15 are not covered by the resist opening 1
The cross-sectional shape of the resist opening 17 can be formed almost vertically without the bottom of the bottom 7 having a hem.

As described above, in the formation of the resist pattern on the substrate that eliminates the proton H ⁺ that contributes to the photosensitivity of the chemically amplified resist, the reaction for eliminating the proton H ⁺ between the resist and the substrate is performed. I am trying to prevent it.

That is, the resist is divided into two layers, and first,
After the proton H ⁺ is generated in the lower layer resist to terminate the reaction of disappearing the proton H ⁺ which occurs near the interface between the resist and the substrate, the upper layer is exposed, that is, the resist pattern is formed. This makes it possible to prevent the disappearance of the proton H ⁺ generated in the upper resist layer. Therefore, when forming a resist pattern at a level of sub-quarter micron or less using a chemically amplified resist, when a positive resist is used, the trailing phenomenon at the bottom of the resist opening after development may occur. This can be avoided and the resist pattern can be formed so that its cross-sectional shape becomes vertical, so that it is possible to suppress the pattern dimension conversion difference in the next etching step or the like.

Moreover, the chemically amplified positive resist 12,
Since ethyl lactate and MMP thinner are used as solvents in 14 respectively, there is no adverse effect on the external environment.

In the above embodiment, the case where ethyl lactate was used as the solvent for the chemically amplified positive resist 12 and MMP thinner was used as the solvent for the chemically amplified positive resist 14 was described, but the present invention is not limited to this. For example, even when MMP thinner is used as the solvent of the chemically amplified positive resist 12 and ethyl lactate is used as the solvent of the chemically amplified positive resist 14, the same effect as in the above-described embodiment can be obtained.

Further, the present invention is not limited to the case of using the positive type resist, and the same operation can be performed by using the negative type resist, for example. FIG. 2 shows a method of forming a resist pattern when a chemically amplified negative resist is used.

In this case, similarly to the above-described embodiment, first, the laser light 13 having the energy not reaching the exposure threshold level is irradiated to the lower negative resist 21 and the substrate 1.
After the disappearance reaction of the proton H ⁺ that occurs near the interface with 1 is terminated, the electron beam 15 is irradiated to expose the negative resist 22 in the upper layer with a desired resist pattern, whereby the resist opening after development is opened. It becomes possible to avoid the occurrence of the bite phenomenon at the bottom of the portion 23.

As a result, the resist pattern can be formed so as to have a vertical cross-sectional shape, and the pattern size conversion difference in the next etching step or the like can be suppressed to a small value.

Also in the case of this embodiment, the negative resist 2
One of ethyl lactate and MMP thinner can be used as the solvent 1, and the other of ethyl lactate and MMP thinner can be used as the solvent of the negative resist 22.
Of course, various modifications can be made without departing from the scope of the invention.

[0032]

As described above in detail, according to the present invention, it is possible to form the resist pattern so that the cross-sectional shape becomes vertical, and it is possible to suppress the pattern size conversion difference in the next step to be small. Can be provided.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a method of forming a resist pattern when a chemically amplified positive resist according to an embodiment of the present invention is used.

FIG. 2 is a sectional view showing a method of forming a resist pattern when a chemically amplified negative resist is used according to another embodiment of the present invention.

FIG. 3 is a cross-sectional view of a resist pattern formed using a chemically amplified positive resist shown in order to explain the conventional technique and its problems.

FIG. 4 is a sectional view of a resist pattern similarly formed using a chemically amplified negative resist.

[Explanation of symbols]

11 ... Substrate, 12 ... Chemically amplified positive resist (first chemically amplified resist), 13 ... Laser light, 14 ... Chemically amplified positive resist (second chemically amplified resist), 1
5 ... Electron beam, 16 ... Exposure area, 17, 23 ... Resist opening, 21, 22 ... Chemical amplification type negative resist.

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location G03F 7/20 521 7/30 H01L 21/027 H01L 21/30 573

Claims (6)

[Claims] 1. A first step of coating a first chemically amplified resist containing a first solvent on a substrate, baking, and then exposing the entire surface with ultraviolet light having energy below an exposure threshold level. A second chemically amplified resist containing a second solvent different in solvent from the first resist is applied on the first resist, and after baking, a desired pattern is exposed by an electron beam. And a third step of developing the first and second chemically amplified resists, the method of manufacturing a semiconductor device. 2. The semiconductor device according to claim 1, wherein the first and second chemically amplified resists are positive type resists composed of a three-component system of resin, acid generator and solvent. Production method. 3. The semiconductor device according to claim 1, wherein the first and second chemically amplified resists are negative type resists composed of a three-component system of resin, acid generator and solvent. Production method. 4. The first solvent in the first chemically amplified resist is either ethyl lactate or MMP thinner, and the second solvent in the second chemically amplified resist is ethyl lactate. 2. The method of manufacturing a semiconductor device according to claim 1, wherein the MMP thinner is one of the other. 5. A first chemically amplified positive type resist consisting of a three-component system in which a resin, an acid generator and a solvent are either ethyl lactate or MMP thinner is coated on a substrate,
After baking, a step of exposing the entire surface with ultraviolet light having a wavelength of 250 nm or less and energy lower than the exposure threshold level and further baking, a resin, an acid generator and a solvent of ethyl lactate on the first resist. , A second chemically amplified positive resist consisting of a three-component system, which is the other of MMP thinner,
After baking, a step of irradiating an electron beam to expose a desired pattern and further baking, and developing the first and second chemically amplified positive type resists,
And a step of opening the electron beam irradiation portion substantially vertically. 6. A first chemically amplified negative resist consisting of a three-component system in which a resin, an acid generator and a solvent are either ethyl lactate or MMP thinner is coated on a substrate,
After baking, a step of exposing the entire surface with ultraviolet light having a wavelength of 250 nm or less and energy lower than the exposure threshold level and further baking, a resin, an acid generator and a solvent of ethyl lactate on the first resist. , A second chemically amplified negative resist consisting of a three-component system, which is the other of MMP thinner,
After baking, irradiating an electron beam to expose a desired pattern, and further baking, and developing the first and second chemically amplified negative resists,
A method of manufacturing a semiconductor device, which comprises the step of opening substantially vertically while leaving the electron beam irradiation portion.