JPS6270837A - Positive resist and its formation - Google Patents

Abstract

PURPOSE:To obtain a positive photoresist having improved heat resistance contg. a photosensitive agent and a crosslinking agent by using a photosensitive crosslinking agent which is not sensitized by the exposure wavelength of the photosensitive agent or using a heat sensitive crosslinking agent which does not cause reaction by the exposure. CONSTITUTION:Heat resistance of a polymer is enhanced by causing crosslinking of a positive photoresist admixed with a crosslinking agent before or after patterning by treating with heat or light depending on the kind of the crosslinking agent. The treated polymer is subjected to RIE or other treatment. The low mol.wt. components in the positive photoresist are increased in their mol.wt. by the crosslinking agent, and the heat resistance of the product is improved, generating no shear of patterning. The effect is also attained when ion implantation or dry etching is performed. Further, since the crosslinking agent is not sensitized by the light having a wavelength causing a reaction of the photosensitive agent, the function as a photoresist is not at all inhibited.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a positive resist and a method for forming a positive resist. This technique can be used, for example, in the field of photoresists used in photolithography processes for semiconductor devices.

[Summary of the invention]

The present invention improves the heat resistance of a positive resist by containing a crosslinking agent and reacting the crosslinking agent.

[Conventional technology and its problems]

Resists used in photolithography processes in semiconductor device processes are required to have high heat resistance. If heat resistance is low, the resist will soften due to heat generated during dry etching or ion implantation, causing pattern deformation, making it impossible to obtain the desired line width, which may be the main cause of deterioration in processing accuracy. It is from.

For example, as shown in FIG. 3, even if a resist 2 is formed in a pattern with a predetermined line width W on the object 1 to be etched, the heat resistance of the resist 2 is poor and the resist bake (beta in the pre-stage of resist baking) is difficult. It has already been deformed due to heat and is 2a in the figure.
If such a shape is obtained, even if etched by RIE or the like, the workpiece 3a will be etched with a line width W' larger than W, and the desired shape will not be obtained. Even if the resist does not deform during post-bake and maintains its original shape as shown in 2b and 2c, the heat generated during RIE causes the resist to deform and sag, resulting in processed products as shown in 3b and 3c. , I still don't get what I want. Further, even if there is no change during post-baking, the same problem will occur if it is deformed during baking. As a result, there is also the problem that the baking temperature cannot be increased.

On the other hand, this problem has become even more important recently as there is a tendency for resists to have lower molecular weights in order to achieve higher resolution. This is because the lower the molecular weight, the worse the heat resistance becomes.

Additionally, there is a movement to require even higher heat resistance for resists in subsequent steps after photolithography, such as dry etching and ion implantation.

Therefore, there is a strong need for a technology that improves heat resistance without reducing resolution.

[Problem that the invention seeks to solve]

As mentioned above, conventional resists have a problem in that heat resistance must be improved without degrading other resist properties.

The present invention was made against this background, and an object of the present invention is to provide a technology that can improve heat resistance without deteriorating resist performance such as resolution and sensitivity. By improving the heat resistance, the process stability of various processes such as SiOz dry etching can be improved.

[Means for solving problems]

The present invention is a positive resist containing a photosensitive main agent and a crosslinking agent, and the crosslinking agent is a photosensitive crosslinking agent that is not sensitive to the exposure wavelength of the photosensitive main agent or a heat-sensitive crosslinking agent that does not react with exposure. This solves the above problems.

Further, in the present invention, the positive resist includes a step of patterning a positive resist containing a photosensitive main agent;
A step of adding a photosensitive cross-linking agent that is not sensitive to the exposure wavelength of the photosensitive main material or a heat-sensitive cross-linking agent that does not react with exposure before or after the patterning step, and a step of reacting the cross-linking agent after the patterning step. It can be formed by a method having.

In addition, when adding a crosslinking agent after patterning the resist, a crosslinking agent that crosslinks at the photosensitive wavelength of the resist can also be used.
In this case, the crosslinking agent is optional.

[For production]

Since the present invention has the above configuration, for example, as illustrated as an example in FIG. 1, a crosslinking agent is added to a positive resist before or after patterning, and the state shown in FIG. 1 is obtained. is treated with heat or light depending on the type of cross-linking agent to cross-link the cross-linking agent therein, resulting in a state containing a highly heat-resistant polymer such as C, and this is RI as shown appropriately.
E can be used for other treatments.

The crosslinking agent turns even low molecular weight materials into polymers, improving heat resistance. Therefore, there is no deviation in patterning, and this is true even when ion implantation or dry etching is performed.

In addition, since the crosslinking agent is not sensitive to light of a wavelength at which the photosensitive main agent reacts, it does not inhibit the function of the photoresist in any way.

When carrying out the present invention, it is possible to add a crosslinking agent in advance to a positive resist containing a photosensitive main agent before patterning, or to apply (or apply) a crosslinking agent after patterning a positive resist containing a photosensitive main agent. It is also possible to impregnate only the resist with this crosslinking agent by post-cleaning), and then react with heat or light to cause crosslinking polymerization.

In the latter case, a crosslinking agent that is sensitive to the same wavelength as the resist can be used.

〔Example〕

An embodiment of the present invention will be described below. It should be noted that, as a matter of course, the present invention is not limited to the following examples and other illustrations.

In this example, 0.5 to 10 wt % of a heat-sensitive or photosensitive crosslinking agent that is not sensitive to UV light is mixed into a phenolic resin UV positive resist.

This crosslinking agent polymerizes the resist to make it into a polymer.

For example, 3,3'-diazide diphenyl sulfone shown in the following formula is added to 0FPR800 (trade name, manufactured by Tokyo Ohka ■).
When wt% was mixed, the heat resistance improved from 120°C to 130°C or higher.

3.3'-Diazidiphenylsulfone The data of the positive resist used, 0FPR800, are as follows.

Weight average molecular weight M. = 12,190 number average molecular weight MN = 917 dispersed layer M,
/MN = 13.3 maximum high molecular weight 1
66.000 In this example, as mentioned above, the heat resistance is 13
Although the Q'C was improved above 130℃ in the post-process,
Since the temperature rises to about 100%, the above is sufficient to achieve the purpose. Incidentally, as shown in FIG. 2, by changing the mixing amount, an improvement in heat resistance of about 30° C. can be achieved.

3. Thermal crosslinking of 3'-diazidiphenylsulfone and phenol resin is thought to proceed according to the following formulas (1) and (2).

■ Phenol resin, that is, ■ N2 dissociates from N3- by heating, 3.3
'-Diazidiphenyl sulfone becomes excited. Then, ■ a dehydrogenation reaction occurs with the phenol resin and crosslinking occurs.

J2 This reaction and other improvements in heat resistance mentioned above are
Deep UV light irradiation may also be used.

This reaction can proceed during post-baking of the resist, and can be carried out by the steps shown in FIG. This improves subsequent heat resistance.

Note that 3,3'-diazide diphenyl sulfone was not sensitive to UV light, so it did not affect patterning. (U
There is no absorption of V light).

This example can be easily adopted without any process changes other than adding the above-mentioned brightening agent to the υVV positive resist.

Further, according to this embodiment, as mentioned above, normally the temperature is 120°C.
The baking temperature of a resist that can only be used up to 130.degree.

〔Effect of the invention〕

As described above, according to the present invention, the heat resistance of the positive resist can be improved without affecting other properties of the resist, which is advantageous for forming a desired pattern, and improves stability in various processes. can be achieved.

[Brief explanation of drawings]

FIG. 1 is a pre-process explanatory diagram of an embodiment of the present invention. Second
The figure is an explanatory diagram of the effects of the embodiment. FIG. 3 shows the prior art. 1.----Etched object, 2--Resist. Patent applicant Toru Takatsuki, Patent attorney representing Sony Corporation Post-bake Yotsuka IE Attack on city procedure Main car official letter (Method) December 3, 1985 Commissioner of the Patent Office Michibu Uga 1, Indication of the case Showa 1960 Patent Application No. 210860 3, Relationship with the person making the amendment Patent applicant address 6-7-35, Tokyo Parts Designed Product Name
(218) Sony Corporation 4, Agent (1) In the specification, on page 3, line 12, "(beta before resist baking)" is corrected to "(baking after resist development)." (2) Same as above, on page 4, lines 1 to 4, "There is also a time when post-bake..." is deleted. (3) Same, page 7, lines 4 to 6, “Crosslinking agent...
Delete "Register only". (4) "Phenol resin" in the same page, 6 lines from the bottom of page 7
is corrected to "phenol novolak resin". (5) Same, in the 7th line from the bottom of page 8, “in the post-process” is changed to “
The post-process is corrected. (6) Same as above, in the 6th line from the bottom of the 8th line, "Raise the temperature to a certain level" is corrected to "Raise the temperature to a level below". (7) Same, change “Temperature 30” in the 4th line from the bottom of No. 8 to “1”
5”. (8) Same, page 9 is amended as per page 9 of the attached appendix. (9) Same, on page 10, line 3, amend ``Owo waite'' to ``Oto wo waite''. (10) Figures 2 and 3 will be corrected according to the attached correction drawings. This is considered to be the above. ■ Phenolic resin ÷ raw hakama

Claims (1)

[Scope of Claims] 1. Positive-type, which contains a photosensitive main agent and a crosslinking agent, and the crosslinking agent is a photosensitive crosslinking agent that is not sensitive to the exposure wavelength of the photosensitive main agent or a heat-sensitive crosslinking agent that does not react with exposure. Resist. 2. A step of patterning a positive resist containing a photosensitive main material, and a photosensitive crosslinking agent that is not sensitive to the exposure wavelength of the photosensitive main material, or a heat-sensitive crosslinking agent that does not react with exposure, before or after the patterning step. A method for forming a positive resist, comprising: a step of adding the crosslinking agent; and a step of reacting the crosslinking agent after the patterning step. 3. A method for forming a positive resist, comprising the steps of: patterning a positive resist containing a photosensitive main agent; thereafter adding a crosslinking agent to the positive resist; and reacting the crosslinking agent. .