KR19980027924A - Composition of Chemically Amplified Resist - Google Patents

Abstract

Disclosed are compositions of chemically amplified resists. This is a base resin composed of polyhydroxystyren (PHS) containing a moiety substituted with an alkyl or allyl group having a tertiary butoxy end group as a dissolution inhibiting group, and an acid group by exposure. In a composition of a chemically amplified resist comprising triphenylsulfonium triflate, which is a photoacid generator for generating H +), and a solvent, which is methyl 3 methoxy propionate, The composition of the chemically amplified resist characterized in that it further comprises a picoline (picoline) derivative represented by the following formula (4) which is an acidic radical inhibitor to prevent the acidic radicals generated from the photoacid generator by the outside To provide. Thereby, it can suppress that the acidic radical generate | occur | produced by exposure until the post-exposure image development for forming a resist pattern diverges to outside of a resist.

Description

Composite of chemically amplified resist

The present invention relates to a composition of a chemically amplified resist, in particular an acid group (H +) generated from a phto acid generator by exposure in a photolithography process after an exposure step. It relates to a composition of a chemically amplified resist, characterized in that the addition of picoline derivatives to suppress the release of acid groups in order to inhibit the release from the inside of the resist up to the development stage.

According to the high integration of semiconductor devices, the pattern of semiconductor devices should be formed into sub-micron fine patterns. Efforts have been made in various parts of manufacturing semiconductor devices. Such efforts have been made in the photolithography process, and research into light sources and resists is being actively conducted.

Chemically amplified resists are photoresists that have emerged as a result of the above research, and are currently being actively applied in photolithography processes in semiconductor manufacturing processes. Chemically amplified resist (also referred to as CAR) refers to resists with quantum yields greater than 100%, where the acid groups (H +) generated from the photoacid generator by exposure are part of the base resin. It is a kind of photoresist that can change the solubility of the base resin in the developer by acting as a catalyst of the reaction for dissolving the dissolution inhibitor introduced from the base resin.

Chemically amplified in chemically amplified resists is a relatively difficult chemical reaction that generates acid groups (H +) relatively easily by exposure and decomposes dissolution inhibiting groups from the base resin by the acid groups (H +). Means to cause).

Conventional chemically amplified resists include a photoresist generator which generates acid groups by exposure, mainly comprising a base resin, a polymer material in which a dissolution inhibitor is introduced, in order to control the rate of dissolution in a developer. Consists of a composition.

When the chemically amplified resist is used in a photolithography process, a development step of removing a resist, which is not necessary for forming a resist pattern, that is, a non-exposed portion, after applying the resist onto a semiconductor substrate, for example, by spin coating. The following is a brief overview.

That is, after the photoresist is coated on the desired wafer, a pre exposure bake step, which is performed to stabilize the photoresist by removing the solvent of the photoresist, and a dissolution inhibiting group introduced to a part of the base resin An exposure step of exposing a predetermined portion of the photoresist to a light source through a photo mask so that acid groups capable of decomposing from the base resin are generated from the photo acid generator, followed by the remaining wavelengths in the photoresist film. Post-exposure bake for the purpose of mitigating continued generation of acid radicals after exposure from the generator, removing solvents that may still remain in the photoresist, and improving the vertical profile of the resist pattern Post exposure bake step (also called PEB step) Proceeds to the step of developing by removing the unexposed portion of the resist to form a resist pattern (develop step).

In this case, in the PEB step, a resist pattern can be formed while continuously maintaining high transparency by dissolving the dissolution inhibiting group from the base resin while continuously dispersing the acid groups (H +) generated in the exposure step into the resist. The process is characteristic of chemically amplified resists.

By the way, during the progress of the photolithography process using the conventional chemically amplified resist, there arises a problem that the acid generated from the photoacid generator by exposure is emitted to the outside in the resist with the progress of the process after the exposure. . This is specifically a phenomenon in which acid groups generated in the resist are neutralized and extinguished at the resist surface by alkali species outside the resist, or they are evaporated to the outside through the resist surface.

The decrease in acid concentration in the resist caused by this phenomenon is characterized by a continuous deprotection reaction which can degrade the dissolution inhibiting group from the base resin during the time from the exposure step to the development step, that is, the delay time. And interferes with the uniform progression, which eventually leads to a mismatch with the chemically amplified resist described above.

As such, when the concentration of the acid generated by the exposure decreases due to the above divergence phenomenon, the reaction of decomposing the dissolution inhibiting group from the base resin of the resist does not proceed smoothly, and thus, after the resist pattern is formed, In the government, a poorly soluble layer for the developer is formed, which results in a defective pattern called a T-shaped malformed structure or undercut in the resist pattern which has been developed. If a bad pattern is formed in the resist pattern, a defect is caused in the pattern of the subsequently formed semiconductor device by using it as a mask, and thus a semiconductor device requiring a fine pattern of high sensitivity and high resolution. A problem arises that cannot be harmonized with high integration.

The technical problem to be achieved by the present invention is to prevent the concentration of acid groups generated by exposure during the photolithography process from being emitted to the outside from within the resist from the exposure step to the development step. It is an object of the present invention to provide a composition of a chemically amplified resist that can achieve.

The composition of the chemically amplified resist provided by the object of the present invention for solving the above technical problem of the present invention is an alkyl or allyl group having a tertiary butoxy (t-Butoxy) end group as a dissolution inhibiting group A base resin comprising polyhydroxystyren (PHS) represented by the following Chemical Formula 1 containing a substituted moiety and a triphenylsulfonium triflate represented by Chemical Formula 2 which generates an acid group by exposure. In the composition of a chemically amplified resist comprising a photoacid generator, and a methyl-3-methoxypropionate (MMP) represented by the following formula (3) which is a solvent thereof, the chemical The composition of the amplified resist has an acidic divergence suppression for preventing the acid groups generated from the photoacid generators from being emitted by the exposure to the outside. To Jane it is characterized in that the form further comprises a picoline (picoline) derivative represented by the formula (4).

In this case, the picoline (picoline) derivative, it is preferable to have a content of 1 to 10 mol percent (mol%) with respect to the photoacid generator.

As such, an acidic divergence inhibitor, such as a picoline derivative, is added to the composition of a conventional chemically amplified resist, thereby coupling with an acid generated from the photoacid generator by exposure such that the acid groups resist from the resist. It can suppress the divergence from the outside.

Hereinafter, the present invention will be described in more detail with reference to an embodiment according to the present invention.

The chemically amplified resist according to the present invention has a base resin, a photoacid generator, a solvent in which a dissolution inhibiting group is introduced, and an acid group generated in the photoacid generator after exposure is emitted from the resist from exposure to development. In order to prevent the acid composition to contain a picoline derivative (picoline) derivative, the content of each composition can be variously formulated.

In this specific example, the polymer material constituting the base resin has an average molecular weight of about 17000, and the ratio between the monomers whose terminals are substituted with dissolution inhibiting groups and the unsubstituted monomers is the same (1: 1). On the other hand, when the composition content of each of the components is expressed as a mass relative to the solvent 120ml, the mass of the total base resin is 35g, the photoacid generator is 2.0g, the picoline derivative (picoline derivative) is A composition of a chemically amplified resist formulated with a composition component content of 2.35 g can be prepared. The advantages of the present invention will be described by observing a resist pattern formed by using the prepared chemically amplified resist composition.

Specifically, using the composition of the chemically amplified resist having the composition component content described above, the resist is applied by spin coating the bare silicon wafer to have a thickness of 0.6 μm, and the resist is applied. The layer was prebaked for 60 seconds at 100 ° C. before exposure and then exposed to deep UV (248 nm) excimer scanner to use a developer, such as 2.38 aq% TMAH. In the end, a resist pattern having a 0.28 µm line / space pattern can be obtained.

At this time, by observing the resist pattern formed by varying the delay time from the exposure step to the development step, it is possible to grasp the effect of the present invention more clearly. That is, when a plurality of wafers are exposed under the same conditions and then developed immediately after the exposure bake treatment (Example 1), thereafter one hour (Example 2), three hours (Example 3), six hours (Example 4) and When the resist pattern formed by developing the resist on each wafer after the heat time (Example 5) has elapsed is observed, the resist pattern of the wafer developed within six hours after the exposure (Examples 1 to 4) is T. It can be confirmed through experiments that a bad pattern such as a mold malformation is not generated.

As a result, the additive material for coupling with the acid group of the chemically amplified resist composition according to the present invention prevents acid group divergence in the resist for at least six hours from exposure to development, thereby reducing the acid group concentration, thereby reducing the resist pattern. It can be seen that the above-described problems using the composition of the conventional chemically amplified resist formed can be effectively prevented.

Specifically, in the case of forming a resist pattern using only a conventional composition in order to confirm such an effect, when a resist is developed on a wafer that has elapsed one hour after baking after exposure, a defective pattern of a T-type structure occurs in the resist pattern on the wafer. Can be observed. From this, the effect which this invention brings can be confirmed more reliably.

The present invention is not limited to the above embodiments, and it is apparent that more modifications are possible by those skilled in the art within the technical idea of the present invention.

When the resist pattern is formed using the chemically amplified resist composition according to the present invention, the concentration of the acid groups generated after exposure can be suppressed from being diverged from the resist from immediately after exposure to development. Therefore, a good resist pattern capable of forming a fine pattern corresponding to high integration of the semiconductor element can be formed.

Claims (2)

As a chemically amplified resist, a base resin comprising a polyhydroxystyren (PHS) represented by the following Chemical Formula 1 including a moiety substituted with an alkyl or allyl group having a t-Butoxy end group as a dissolution inhibiting group; A photoacid generator which is triphenylsulfonium triflate (TSF) represented by the following Chemical Formula 2 to generate an acid group by exposure; And In the composition of the chemically amplified resist comprising methyl-3-methoxypropionate (MMP) represented by the following formula (3) which is a solvent thereof, The composition of the chemically amplified resist is formed by further comprising a picoline derivative represented by the following formula (4) which is an acid radical release inhibitor for preventing the acid groups generated from the photoacid generator by the exposure to the outside A composition of chemically amplified resist, characterized in that. [Formula 1] [Formula 2] [Formula 3] [Formula 4] According to claim 1, The picoline derivative, the composition of the chemically amplified resist, characterized in that the content of 1 to 10 mole percent (mol%) relative to the photoacid generator.