Resist polymer and method for producing the polymer

Abstract

Solving problems in the prior art, provided are a resist polymer which is small in lot-to-lot, reactor-to-reactor and scale-to-scale variations, and contains no high polymer, is excellent in solubility and storage stability, and is suitable for fine pattern formation, and a method for production thereof. The present invention provides the resist polymer at least having a repeating unit having a structure which is decomposed by an acid to become soluble in an alkali developer and a repeating unit having a polar group to enhance adhesion to a substrate, characterized in that a peak area of a high molecular weight component (high polymer) with molecular weight of 100,000 or more is 0.1% or less based on an entire peak area in a molecular weight distribution determined by gel permeation chromatography (GPC).

Description

RELATED APPLICATIONS [0001] This application is a Division of U.S. patent application Ser. No. 10 / 775,695, filed Feb. 10, 2004 entitled RESIST POLYMER AND METHOD FOR PRODUCING THE RESIST POLYMER. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates to a resist polymer used for the production of semiconductors and a method for the production thereof. More particularly, the present invention relates to the resist polymer, which is suitable for microfabrication using various radiations such as far ultraviolet ray, X-ray and electron beam, and excellent in storage stability, and the method for production thereof. [0004] 2. Description of Related Art [0005] In semiconductor lithography, the formation of finer patterns has been required in conjunction with increase of integration degree. It is essential for micropatterning techniques to make a wavelength of light source shorter. Currently, the lithography by krypton fluoride. (KrF) excimer lase...

AI Technical Summary

Benefits of technology

[0043] The present invention has been completed against the above background, and the objective thereof is to provide a resist polymer which is small in lot-to-lot, reactor-to-reactor, and scale-to-scale variations, and does not contain a high polymer, is excellent in solubility and storage stability, and is suitable for fine pattern formation in the semiconductor lithography, and a method for the production thereof.

[0044] As a result of an intensive study for solving the above problems, the present inventors have found that a monomer can be introduced into a system without being subject to a temperature-rising rate and concurrently it is possible to suppress the generation of a high polymer by introducing a basic ingredient monomer and a polymerization initiator by a particular method in the drop polymerization method, and resist polymer which is excellent in solubility and storage stability is obtained, and have completed the invention.

Problems solved by technology

However, in the batch polymerization method, it is difficult to control a temperature-rising rate constantly at all times. Therefore, there has been a drawback that difference in amount of generated radical species occurs at a stage of temperature-rising due to subtle variations in the temperature-rising rate and causes lot-to-lot variations in molecular weight distribution.

In addition, in the case of batch polymerization method, even if the same temperature-rising rate is reproduced, there has been a drawback that difference of a radical concentration occurs in the temperature-rising process due to batch-to-batch variations in amount of dissolved oxygen, because a trace quantity of radical generated by partial decomposition of the polymerization initiator in the temperature-rising process is trapped by dissolved oxygen in the polymerization solvent.

Additionally, since there is a period of a low radical concentration and a high monomer concentration in the temperature-rising process in the batch polymerization method, there has been a problem that a trace amount of a high molecular weight component (high polymer) with molecular weight of 100,000 or more generates.

However, there has been a problem that a trace amount of high polymer generates because the monomer is heated to the polymerization temperature in the absence of the polymerization initiator in these methods.

However, there has been a problem that a trace amount of high polymer generates because the monomer is retained in the coexistence with a polymerization initiator during the period of the dropwise addition in this method.

However, when a large amount of polymerization inhibitor is added to suppress the generation of high polymer, it likely affects the polymerization reaction.

In addition, in the ArF lithography, there has been a problem that a phenol type compound such as 4-methoxyphenol generally used as the polymerization inhibitor is left in the polymer and absorbs the light with a wavelength of 193 nm.

But there is a possibility of explosion and fire disaster in this method, which could not be industrially practiced in terms of safety.

When the above high polymer generates, solubility of the obtained resist polymer to a resist solution and an alkali developer becomes poor.

It is highly possible that these insoluble matters become a cause of defects of the resist pattern.