JP3271145B2 - Pattern formation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pattern forming method, and more particularly to a pattern forming method for forming a resist film on a substrate to be processed and performing patterning. The present invention can be used as a pattern forming method in various fields, for example,
The present invention can be applied to a pattern forming material in an electronic field (such as a semiconductor device manufacturing field).

[0002]

2. Description of the Related Art Pattern formation in various fields tends to be further miniaturized. For example the minimum feature size of semiconductor integrated circuits has been refined year after year, the research and development level, for example, has led to a level of 0.5μm or less of 0.35 .mu.m. Along with this, even in a photolithography process, that is no longer necessary to control the fine size with high accuracy. For this reason, attempts have been made to shorten the exposure wavelength. This is because the shorter the exposure wavelength, the higher the limit resolution. Under these circumstances, the lithography technology using ultraviolet rays (wavelengths 435 nm and 365 nm) such as g-rays and i-rays emitted from a conventional high-pressure mercury lamp has been used to further shorten the wavelength of KrF.
Excimer laser lithography technology and the like have attracted attention. This is because the KrF excimer laser has a short oscillation wavelength (250 nm) and high resolution is expected.

Generally, it is desired that a resist used for forming a pattern has high sensitivity. In the short wavelength region as described above, a resist having particularly high sensitivity is required. For this reason, a resist composition having higher sensitivity than before has been required, and in this background, for example, a so-called chemically amplified resist has attracted attention. A chemically amplified resist refers to a resist that contributes to the next reaction, such as a substance generated by light, starting or accelerating a reaction such as the next polymerization. Such a chemically amplified resist has an advantage that it can provide high resolution and a good resist shape.

[0004] chemically amplified resist is generally light by generating a reactive substance such as acid or alkali, the reaction raw formed product is in the configuration to cause a crosslinking reaction and other reactions.
For example, typically, a so-called photoacid generator that generates an acid by light is used. In the case of a negative resist, generally, the generated acid causes a crosslinking reaction to cause a solvent (developer) in that portion.
In the case of a positive resist, the generated acid generally acts to remove the protective group of the resin and increase the solubility. Therefore, a negative type chemically amplified resist usually comprises a three-component system of a base resin, a photoacid generator, and an acid crosslinking agent whose crosslinking proceeds with an acid. Alternatively, a functional group can be introduced into the base resin so as to perform any of the functions of the other two components, and the base resin can also be used. In addition, a positive chemically amplified resist usually includes two components, a base resin and a photoacid generator, as essential components, provided that a protecting group is introduced into the base resin or a compound having a separate protective action. And an acid-decomposition-type dissolution inhibitor that normally inhibits solubility. The positive-type chemically amplified resists containing a dissolution inhibitor may be such that the acid generated by light can cause the dissolution inhibition effect to be lost, and the light-irradiated portion can be dissolved by the solvent (developer). It was made.

However, the high-sensitivity resist represented by the chemically amplified resist has a drawback that the sensitivity varies depending on a standing time from application to exposure.

[0006] On the other hand, for example, the KrF excimer laser lithography technique is easily affected by reflection from a substrate, such as when a substrate to be processed is a semiconductor substrate. Therefore, antireflection is required. As an anti-reflection technique, for example, g
In the line and i-line lithography technology, a method of coating an anti-reflection film on a resist surface called an ARCOR method is known. (Tanaka et al., "Proposal of the ARCOR Method for Optical Lithography," Proceedings of the 32nd Federation of Applied Physics, 29a-H-3 (p. 293), Spring 1985. Proposal (2) "Proceedings of the 46th Annual Conference of JSAP, 3p-9
-5 (p. 316), fall 1960). This technique may be applied to the excimer laser roughness technique, but it is not always preferable because of the problem that the process is complicated, such as necessity of peeling.

[0007]

As described above, in the prior art, high-sensitivity resists such as chemically amplified resists have different performances such as a change in sensitivity depending on the situation.
As a result, the processing results fluctuate, for example, the pattern dimensions change.
There is a problem that movement occurs , which is a bottleneck for using a high-sensitivity resist for pattern formation.

Each invention of the present application is intended to solve the above problems, and each invention has a performance such as sensitivity depending on the situation.
To prevent changes in pattern dimensions, etc.
Thus, it is possible to effectively and practically form a pattern with a high-sensitivity resist.

[0009]

Means for Solving the Problems The invention of claim 1 of the present application has achieved the above object by the following constitution .

That is, the invention of claim 1 of the present application provides
Form a resist film with resolution of 0.5μm or less on the body
The minimum processing dimension on the substrate to be processed is 0.5 μm or less.
Pattern forming method for forming a pattern
The resist film contains a photoacid generator that generates an acid by light.
In the case of a negative resist, the generated acid causes a crosslinking reaction.
To lower the solubility of the part in the developer
And the generated acid in a positive resist
Acts to increase the solubility by removing the protecting groups of the resin
Formed by a chemically amplified resist that is a resist, and
On the resist film, polyvinyl alcohols, polyvinyl alcohol,
Among rupyrrolidones, polysaccharides and polyvinyl acetal
Water consisting of one or more materials arbitrarily selected from
Form a soluble polymer film to eliminate contact between the resist and air
In this way, fluctuations in the resolution performance of the resist
Turning, and patterning of the resist film
Is characterized by using an excimer laser.
And a method for forming the same, thereby achieving the above object.
Things.

In each invention, any material can be used as a resist material for forming a resist film. The present invention is particularly effective for a pattern forming method using a highly sensitive resist, for example, a chemically amplified resist.

In the present invention , a water-soluble polymer film made of one or more materials arbitrarily selected from polyvinyl alcohols, polyvinylpyrrolidones, polysaccharides, and polyvinyl acetals is formed on the resist film. By forming the resist and cutting off the contact between the resist and air, patterning is performed while suppressing variation in resolution performance of the resist. That PVA (polyvinyl alcohols), PVP (polyvinyl pyrrolidone), polysaccharides (pullulan, cellulose, etc.), randomly selected from among polyvinyl acetals 1
Use seeds or two or more. PVA is desirable from the viewpoint of effectively shielding the resist film from the atmosphere.

In the present invention , the thickness of the water-soluble polymer film is determined by the wavelength of the excimer laser used as the exposure light used, for example, the KrF excimer laser oscillation wavelength or the ArF excimer laser oscillation wavelength. Can be set to a film thickness that is an antireflection condition determined by the refractive index of the film.

[0014]

According to the first and second aspects of the present invention, it is possible to prevent a change in resolution performance, particularly a change in sensitivity, due to a standing time from application of a resist to exposure or development.

The operation of the present invention is not necessarily clear.
No.

The inventor of the present invention has found that resolution due to variations in the standing time
Changes in performance, especially sensitivity variations, are mainly due to the atmospheric pressure of the resist.
Effects, possibly due to oxygen or humidity.
Air and cash register depending on the specific material
This can be solved by configuring the device to break contact with the strike.
I thought I could come.

As a result of various studies based on this point of view,
The invention was found to solve the problem, and
This is the end of the Ming.

According to the first and second aspects of the present invention, the anti-reflection condition is satisfied.
By forming a water-soluble polymer film with a thickness of
It is possible to have an effective anti-reflection effect more easily than technology
More stable pattern formation
Is also possible.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of each invention of the present application will be described below. However, needless to say, each invention is not limited to the embodiments described below.

Embodiment 1 This embodiment embodies the invention of claim 1.
In particular, in forming a miniaturized / integrated semiconductor integrated circuit device, the present invention is applied to a case where a resist film is formed on a semiconductor substrate, which is a substrate to be processed, with a chemically amplified resist, which is a highly sensitive resist, and patterning is performed. This is an example of application.

In this embodiment, a film was formed by applying a chemically amplified resist and then spin-coating a water-soluble polymer material with an aqueous solvent.

As described above, various kinds of water-soluble polymer materials can be used. Here, PVA is used.
This is because PVA is suitable for practicing the present invention because the molecules are easily aligned and the air permeability is small. More specifically, PV
As A, Nagase & Co., Ltd. trade name barrier coat BC5
Was used. This is because, in the present embodiment, KrF excimer laser light (wavelength 248 nm) is used as the exposure light, and this PVA is preferable for this wavelength.

The operating conditions are KrF excimer stepper (N
A: 0.37) and chemically amplified SAL as resist
A resist film having a thickness of 0.7 μm was formed using 601 ER7 (Shipley Co.), and a water-soluble polymer film was formed thereon using the above-mentioned PVA to coat the resist film.

The pre-bake before exposure was performed at 90 ° C. for 90 seconds, and the post-exposure bake (PEB) was performed at 110 ° C. for 90 seconds. Development is performed using MF, a dedicated developer for the used resist.
Performed for 10 minutes using 622.

Under the above conditions, the following four experiments were performed. That is, the first and second experiments (comparative experiments) did not form a PVA film which was a water-soluble polymer film, and the first experiment had a standing time of 10 minutes before exposure. The second time was also 80 minutes, a 0.4 μm line and space pattern was formed, and the width of the formed pattern was examined. The third,
In the fourth experiment, the present invention was embodied. In each case, a PVA film was formed as a water-soluble polymer film (the film thickness was determined in consideration of the refractive index of this PVA material with respect to KrF excimer laser light, Optimal anti-reflection conditions were set), and in the third experiment, the standing time until exposure was 10
In the fourth test, a line and space pattern of 0.4 μm was formed, and the width of the formed pattern was examined. The exposure dose (Dose) was set to 60 mJ / cm.
The results are shown in the following table. Below margin

[Table 1]

As can be understood from the results in Table 1, an experiment N embodying the method of the present invention in which a water-soluble polymer film was formed was used.
o. In Nos. 3 and 4, the pattern width hardly changed when the leaving time was set to 10 minutes and when the leaving time was set to 80 minutes, and thus it can be seen that the pattern variation due to the leaving time is suppressed. On the other hand, the comparative experiment No. In Examples 1 and 2, the change in the pattern width was large due to the change in the standing time. In this example, an antireflection effect was also effectively obtained.

Embodiment 2 This embodiment embodies the second aspect of the present invention.
As in the first embodiment, in particular, when forming a miniaturized and integrated semiconductor integrated circuit device, patterning is performed by forming a resist film with a chemically amplified resist which is a highly sensitive resist on a semiconductor substrate which is a substrate to be processed. The following is an example in which the present invention is applied.

Specifically, the test was performed under the following conditions. That is, as a semiconductor substrate to be processed, a 5-inch silicon wafer which had been subjected to a dehydration bake at 200 ° C. for 1 minute and then subjected to a hydrophobic treatment with hexamethyldisilazane vapor for 1 minute was subjected to SAL601ER7.
(Shipley Chemically Amplified Resist) spin-coated and 9
By baking at 0 ° C. for 90 seconds, a resist film having a thickness of 0.7 μm was formed. This is shown in Table 2 below.
After storage in Nos. (1) to (10)), exposure was performed to form a 0.45 μm contact hole. The dimensions of the contact holes obtained in each experiment were measured at the same dose. The development conditions were development with a developer MF-622 for 10 minutes. The dose was 70 mJ / cm ² and the post-exposure bake (PEB) was 110 mJ / cm ^2.
C. for 60 seconds. The results are shown in Table 2 below. Below margin

[Table 2]

As can be understood from Table 2, if the present invention is applied and the atmosphere is kept at a relative humidity of 40% or less, even if stored for one day (24 hours), there is no problem in pattern dimension variation. I understand.

Separately, the same effect was obtained by using XP-8843 (Shipley) as a resist under the same conditions as in this example.

[0031]

As described above, according to each invention of the present application,
It is possible to solve the problem that the processing result fluctuates due to a performance change such as a change in sensitivity depending on the situation, for example, the pattern dimension fluctuates, and a pattern with a small processing fluctuation can be formed.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-204848 (JP, A) JP-A-3-156914 (JP, A) JP-A-2-248953 (JP, A) JP-A-2-204 50164 (JP, A) JP-A-1-159642 (JP, A) JP-A-2-53062 (JP, A)

Claims (1)

(57) [Claims] 1. A pattern forming method for forming a resist film having a resolution of 0.5 μm or less on a substrate to be processed and forming a pattern with a minimum processing dimension of 0.5 μm or less on the substrate to be processed. The resist film contains a photoacid generator that generates an acid by light.
In the case of negative resist, the generated acid causes a crosslinking reaction
And the solubility of the part in the developer is reduced.
And in the case of a positive resist,
Acid acts to remove the protecting groups on the resin and increase solubility
That resist such as a formed from the chemical amplification resist, and on the resist film, polyvinyl alcohols, polyvinyl pyrrolidones, consisting polysaccharides, one or more materials selected arbitrarily from among the polyvinyl acetals By forming a water-soluble polymer film and cutting off the contact between the resist and air, patterning is performed while suppressing variation in resolution performance of the resist, and the resist film is patterned using an excimer laser. Pattern forming method.