JPH0695387A - Photoresist composition - Google Patents

Abstract

PURPOSE:To provide a novel photoresist compsn. suitable for forming a fine pattern and to provide a novel photoresist compsn. usable as a compsn. having satisfactory shelf stability. CONSTITUTION:A resin convertible into an alkali-soluble resin when protective groups such as tertiary butyl groups are removed by fluorine and a compd. which releases fluorine when irradiated with active energy beams such as light, e.g. an s-triazinefluoro compd. are used as constituents. The objective photoresist compsn. capable of forming a fine pattern and also capable of ensuring satisfactory shelf stability can be obtd.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to photoresist compositions. INDUSTRIAL APPLICABILITY The present invention can be used, for example, when performing fine processing in photolithography technology.

[0002]

2. Description of the Related Art Conventionally, photoresist compositions have been used in various fields. For example, it is used as a photoresist used in the photolithography technology of electronic materials, particularly semiconductor devices.

By the way, for example, the minimum feature size of a semiconductor integrated circuit is becoming finer year by year, and is approaching the level of 0.35 μm, for example. Along with this, it is necessary to control fine dimensions with high precision in the photolithography process. Therefore, attempts have been made to shorten the exposure wavelength. This is because the shorter the exposure wavelength is, the more the limiting resolution is improved. Under such circumstances, a KrF excimer laser lithography technique (wavelength 250 nm) having a shorter wavelength (higher resolution) or the like is attracting attention from the conventional g-line or i-line lithography technique.

On the other hand, with the shortening of the wavelength of the above-mentioned lithography technique, a photosensitive composition called a so-called chemically amplified resist is drawing attention. This is because the chemically amplified resist material is easy to design, and it is easy to produce a transparent and good shape. What is a chemically amplified resist?
It is a resist in which a substance generated by light initiates or accelerates a reaction such as the next polymerization and contributes to some next reaction. Such a chemically amplified resist generally has an advantage of high resolution in spite of high sensitivity.

A chemically amplified resist typically uses a so-called photo-acid generator which generates an acid by light. In a negative resist, a generally generated acid causes a cross-linking reaction to cause a solvent at that portion. It acts to reduce the solubility in (developer), and in the case of a positive resist, the acid generally generated acts to remove the protective group of the resin and enhance the solubility. Therefore, a negative chemically amplified resist is usually composed of a three-component system including a base resin, a photo-acid generator, and an acid cross-linking agent that undergoes cross-linking by an acid. Alternatively, it is also possible to introduce a functional group into the base resin so as to perform the function of either of the other two components, so that the base resin is also used. In addition, the positive type chemically amplified resist is usually a two-component type containing a base resin having a site blocked by a protective group having a dissolution inhibiting function and a photoacid generator, a dissolution inhibitor and a photoacid generator. There is a three-component type consisting of an agent and a base resin.

For example, as a material for a positive chemically amplified resist, a phenolic hydroxyl group protected by a tBOC group is used as a photoacid generator (mainly onium salt, sulfone,
It has been proposed that the part irradiated with light is dissolved by deprotection with o-nitrobenzyl ethers). In addition, those protected with a trimethylsilyl group have been studied. For example, Journal of
Photopolymer Science and
Technology, Vol 4, No. 3,19
91 (pages 509 to 516) shows the patterning evaluation result of the material protected by the trimethylsilyl group.

[0007]

As mentioned above, various resist compositions have been studied and proposed.
Along with the miniaturization of the processing pattern size, a new resist composition which is more excellent in various points is desired.

For example, there is a demand for a resist composition having better storage stability than the above resist composition.

An object of the present invention is to provide a novel photoresist composition suitable for forming a fine pattern. Moreover, it aims at providing the novel photoresist composition which can be set as a composition with favorable storage stability.

[0010]

[Means and Actions for Solving Problems] The invention of claim 1 of the present application contains a resin in which a protective group is removed by fluorine to become alkali-soluble, and a compound which releases fluorine by irradiation with active energy rays. A photoresist composition, characterized in that it achieves the above object.

The invention according to claim 2 of the present application is characterized in that the resin which is alkali-soluble by removing the protective group by fluorine is a compound having a group represented by the following general formula (1). Which is the photoresist composition described in
This achieves the above object.

[Chemical 3]

However, R ¹ , R ² and R ³ represent an alkyl group, an aryl group or an aralkyl group.

According to the invention of claim 3 of the present application, a resin whose protective group is removed by a foot to become alkali-soluble is t-B.
The photoresist composition according to claim 2, which is a resin in which a phenolic hydroxyl group is protected by a uMe ₂ Si-group (wherein t-Bu represents a tert-butyl group and Me represents a methyl group). Therefore, the above object is achieved.

The invention according to claim 4 of the present application is characterized in that the compound which releases fluorine upon irradiation with an active energy ray is a compound represented by the following general formula (2): A resist composition, which achieves the above object. However, in the general formula (2), A ¹ , A ² , and A ³ are CnFaHb groups (n is an integer of 1 or more, a is an integer of 1 or more, and b is an integer of 0 or more, a
+ B = 2n + 1), which may be the same or different.

[Chemical 4]

According to the inventions of claims 1 and 2, a novel photoresist composition suitable for forming a fine resist pattern can be provided.

According to the invention of claim 3 of the present application, it is possible to provide a photoresist composition having good storage stability.

That is, in the invention of claim 3, since a material such as a MeSi group (trimethylsilyl group) which is relatively weak in an acidic atmosphere is used and a t-BuMe ₂ Si group is used as a protective group, the stability is good. A resist composition having good storability can be obtained. This resist composition can be stably stored for a long period of time even in the air or a normal atmosphere.

According to the invention of claim 4 of the present application, it is possible to provide a photoresist composition which releases fluorine to surely remove the protective group and makes the resin alkaline. That is, this resist composition has good sensitivity. Even if the protective group is removed by fluorine and becomes alkali-soluble, a chemically stable resin tends not to have the protective group. For example, t- used in the invention of claim 3 above
Resins protected with BuMe ₂ Si groups are generally too stable to be deprotected with common acids (such as hydrochloric acid). In organic synthesis, it is generally removed by using a fluorine ion such as TBAF (tetrabutylammonium fluoride). According to the invention of claim 4, the general formula (2)
By using the compound (2), even such a stable resin can be surely made alkali-soluble and desired patterning can be performed.

Each invention of the present application will be described in detail below. In the invention of claim 1, as the resin whose protective group is removed by the foot to become alkali-soluble, any resin can be used as long as it can be subjected to alkali development to form a pattern.

In the present specification, the active energy ray is a concept including visible rays, infrared rays, ultraviolet rays and the like, as well as electron rays and other various radiations.

Photoablation (photoablation) in which a pattern is obtained by irradiating a fluorine-containing resin with light to blow off the resin in this portion has been proposed, but the conventional technique using a two-component photoresist has been proposed. Not proposed.

In the invention of claim 2, R ¹ , R ² and R ³ in the general formula (1) are any alkyl group (methyl group, ethyl group, propyl group, butyl group, etc.), aryl group (phenyl group, etc.) ), An aralkyl group (benzyl group, etc.), each group may further have a substituent, and R ¹ and R
² and R ³ may be the same or different.

From the viewpoint of stability, R ¹ is a tertiary-butyl group and R ² and R ³ are methyl groups (used in the invention of claim 3).

The protection of the hydroxyl group and the like by the group represented by the general formula (1) or the t-BuMe ₂ Si group of the resin is carried out by a method using a usual chloride, for example, t-BuMe ₂ SiCl.
Can be easily introduced by introducing this group by a method using imidazole (or pyridine) and a DMF solvent.

In the invention of claim 3, in the general formula (2)
The compound represented is A¹, A ², A³Is CnF
_2n-1The S-triazine perfluoro compound of
However, it may not be possible to completely substitute fluorine for synthesis.
However, some hydrogen may be used. Energy such as light
If it can generate fluorine by a line, it should be used
it can.

[0026]

EXAMPLES Examples of the present invention will be described below. However, the present invention is not limited to the following examples.

Example 1 Polyhydroxystyrene protected with t-BuMe ₂ Si (50%) (molecular weight 6000, manufactured by Maruzen Petrochemical) was added to
(C ₄ F ₉ ) ₃ C ₃ N ₃ (In the general formula (2), A ^{1 to} A ³ are n
= 4 fluorocarbon groups. However, hydrogen may be left without being completely fluorinated) in a weight ratio of 10
The mixture mixed at 0: 5 was dissolved in ECA (ethyl cellosolve acetate) (solid content 30%). This was filtered with a membrane filter having 0.2 μm pores to obtain a coating solution.

A 5-inch silicon wafer dehydrated and baked at 200 ° C. for 1 minute was treated with HMDS (hexamethyldisilazane) at 25 ° C. for 1 minute, and the above coating solution
A milliliter was dropped and a film was formed by a spin coating method to a film thickness of 1 μm. After baking at 90 ° C for 90 seconds, K using a chrome reticle having a line and space pattern
rF excimer laser reduction projection exposure system (NS made by Nikon
R1505EX) (NA: 0.42, σ: 0.5) was used for exposure. (Exposure amount 20-80 mJ / c
m ² ). After PEB (post-exposure bake) at 110 ° C. for 90 seconds, a 1.5% TMAH (trimethylammonium hydride) aqueous solution was used as an alkaline developer.
Dip development was performed for 1 minute.

As a result, the line and space of 0.35 μm was resolved.

As described above, according to this example, a positive type chemically amplified resist having a high stability can be provided by using a phenol resin protected with perfluoroalkyl S-triazine and a t-butyldimethylsilyl group.

Examples 2 to 8 Various polymers were used in the same manner as described above, but t-BuMe _{2 was used.}
The same procedure as in Example 1 was carried out using a resin in which a protecting group was introduced by silylation with SiCl in an organic solvent system. Table 1 below shows the polymers used, their molecular weights, silylation rates, photosensitizers and their amounts. Also, the resolving power and the dose amount during exposure are described. The photosensitizer is a compound that releases fluorine by light, and is represented by the carbon number (n) of the compound of the general formula (2) (almost completely fluorinated,
May remain hydrogen on synthesis).

The data of Example 1 are also entered in Table 1.

As is clear from Table 1, 0.35 to 0.
It can be seen that a line and space of 4 μm is resolved and a resist suitable for forming a fine pattern can be obtained.

All the photoresists of Examples 1 to 8 had good storage stability and did not deteriorate due to carbon dioxide or the like even after long-term storage.

[Table 1]

Example 9 Here, a trifluoroacetic acid-based compound, which is a substance that emits fluorine by light, was used as a compound that releases fluorine, which is a photosensitizer. Specifically, the following compounds were used.

[Chemical 5]

Others were the same as in Example 1. As a result, a line and space of 0.4 μm could be resolved.
However, according to Example 1, the sensitivity tended to be poor.

Example 10 In this example, Me ₃ S is used as a resin which becomes alkali-soluble.
Polyhydroxystyrene protected with i group (trimethylsilyl group) was used. Others were the same as in the example. As a result, it works well as a photoresist, 0.4μ
The line and space of m could be resolved. However, the storage stability tended to be inferior to that of the photoresist of Example 1.

[0038]

INDUSTRIAL APPLICABILITY According to each invention of the present application, a photoresist composition suitable for forming a fine pattern can be provided, and a photoresist composition having excellent storage stability can also be provided.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H01L 21/027

Claims (4)

[Claims] 1. A photoresist composition comprising a resin whose protective group is removed by fluorine to become alkali-soluble, and a compound which releases fluorine upon irradiation with an active energy ray. 2. The photoresist composition according to claim 1, wherein the resin which is protected by fluorine to remove the protective group and becomes alkali-soluble is a compound having a group represented by the following general formula (1). [Chemical 1] However, R ¹ , R ² , and R ³ represent an alkyl group, an aryl group, or an aralkyl group. 3. A resin which is alkali-soluble by removing a protecting group by a foot is a t-BuMe ₂ Si-group (provided that t-BuMe ₂ Si-group
(Bu represents a tertiary-butyl group, Me represents a methyl group)
The photoresist composition according to claim 2, which is a resin in which the phenolic hydroxyl group is protected with. 4. The photoresist composition according to claim 1, wherein the compound that releases fluorine upon irradiation with active energy rays is a compound represented by the following general formula (2). [Chemical 2] However, A ¹ , A ² and A ³ are CnFaHb groups (n is an integer of 1 or more, a is an integer of 1 or more, b is an integer of 0 or more,
a + b = 2n + 1), which may be the same or different.