JPS6055824B2 - Sensitive polymer material and its pattern formation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sensitive polymer material useful as a resist material and a pattern forming method thereof.

In recent years, the production of high-density integrated circuits such as LSI requires fine patterns, so conventional photo and phosphorography techniques using visible light and ultraviolet rays have reached their limits, and deep ultraviolet,
Lingraphy technology using electron beams or X-rays has come into use.

For resist materials such as electron beams, positive type resists with good resolution are mainly used, and negative type resists have high sensitivity but poor resolution and can only form patterns of about 2 μm at most, so they are not usually used. There is a tendency. However, negative resists generally have good adhesion because the remaining portions react when irradiated, and are resistant to edge-type etching. This improves the precision of circuit elements, and more UV exposure resists are negative than conventional ones, which is very convenient in terms of process.

The present invention aims to achieve the above object by proposing a negative resist material capable of forming high-precision patterns and a method for forming the same. A negative pattern is obtained by using a functional polymer material, selectively irradiating it with at least one of electron beams, X-rays, α' rays, and deep ultraviolet rays, and developing it with an alkaline developer. To explain the present invention in detail below, Novotek type phenolic resin has been used as a positive resist material by adding a photosensitive substance, for example, naphthoquinone diazide represented by This product is known as resist.

The present invention provides a base material represented by the general formula (R is -H or -CH3, and n is the number) without adding such a photosensitizing substance. This paper proposes a resist material consisting only of polymers.

As a result of our investigation, we found that this type of novolac-type phenolic resin base. It has been found that a negative fine pattern can be obtained by excessively irradiating a polymer with electron beams, X-rays, or deep ultraviolet rays, or by appropriately combining heat treatment and irradiation amount.

Since there is no addition of the above-mentioned photolabile substance, there is no change in the irradiation amount to a positive tone. Next, an example of a method for forming the same will be described. A novolak type phenolic resin with an average molecular weight of 200 degrees is dissolved in methyl cellosolve acetate to form a 20% solution.

This is applied onto a material to be processed, such as a silicon substrate, using a spinner, and then a preliminary heat treatment is performed at a temperature of 80°C. Then, irradiate with an electron beam and increase the irradiation dose to 5
x 10-5 coulombs/cl, and after irradiation, post-irradiation at a temperature of 90°C for 20 minutes. Perform baking (post-exposure heat treatment). Next, an organic alkaline developer (for example, trade name r!o'312
) is diluted with water to make a 25% aqueous solution and developed with this developing solution, a negative pattern with a width of about 1 μm can be formed. Irradiation amount and post explained above. Similarly, a fine negative pattern can be obtained by appropriately adjusting and combining baking and irradiation.

Furthermore, not only an organic alkali developer but also a several percent aqueous solution of caustic potash can be used for development. The reason why such a negative-type fine pattern can be obtained is because the polymer material of the present invention has a lower molecular weight than general negative-type resist materials. The reaction (cross-linking reaction) does not completely gel (insolubilize) the resist, therefore, in general negative resists, the remaining portions that become "beards" or "bridges" are completely dissolved by the developer. It is thought that the resolution is improved because of the fact that swelling is less likely to occur because it is developed with an aqueous solution.

As described above, the present invention provides a negative resist material suitable for forming fine patterns and a method for forming the same, but novolac type phenolic resin is commonly used as a molding material for electronic components. Since it can be obtained at a low price, it is useful for reducing the cost of high-density integrated circuits, etc., and can be said to contribute to the development of not only the semiconductor industry but also the electronic industry.

Claims (1)

[Claims] 1. A sensitive polymer material made of a novolac-type phenolic resin represented by the general formula ▲ Numerical formula, chemical formula, table, etc. ▼ (in the formula, R is -H or -CH_3). 2 General formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (R in the formula is -H or -CH_3) Sensitive polymer material made of novolac type phenolic resin is exposed to electron beams, X-rays, α-rays, etc. A pattern forming method characterized by obtaining a negative pattern by selectively irradiating at least one of deep ultraviolet rays and developing with an alkaline developer.