JPS59132128A - Method and apparatus for forming resist pattern - Google Patents

Abstract

PURPOSE:To shorten the time required for forming a resist pattern by providing a process through which a resist is cooled rapidly after baking the resist and before irradiating electromagnetic waves or particle beams. CONSTITUTION:A substrate 1 to which a pre-baking is completed is shifted to a belt conveyor 9, and carried and introduced to a quenching mechanism 10. The substrate 1 is transferred to a carrier mechanism 11 movable vertically and left and right, dipped in pure water 13 as a liquid refrigerant in a cooling tank 12, and cooled rapidly. The cooled substrate 1 is shifted on a belt conveyor 14 by the conveyor 11, and placed on a rotary sample base 15 for spin drying. The substrate 1 dried by the revolution of the sample base 15 is transferred on a belt conveyor 17 by a vacuum chuck 16, and carried out.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] The present invention relates to a method and apparatus for forming a resist pattern that improves the sensitivity of the resist and speeds up pattern formation.

[Prior art and its problems]

As the integration density of semiconductor elements, including VLSIs, increases, technology for forming finer and 48-degree patterns is required.

On the other hand, in order for such pattern forming technology to be used in mass production or in-line production, high speed is required, and highly sensitive resists are expected.

FIG. 1 shows a conventional resist pattern forming system in which baking (prebaking) is performed at a predetermined temperature (To). Thereafter, the resist film-coated substrate to be processed taken out from the oven is placed on a support stand -F in clean air and allowed to cool naturally to about room temperature over a period of 20 to 30 minutes. The cooled resist film-coated substrate to be processed is selectively irradiated with electromagnetic waves in a predetermined wavelength range, such as ultraviolet light, or particle beams with a predetermined energy, such as electron beams, at a predetermined dose depending on the type of resist. and expose. Thereafter, a desired resist pattern is formed through a development and rinsing process.

FIG. 2 shows how the temperature of the treated fM2i plate changes during the resist natural cooling step. It can be seen from FIG. 2 that conventionally, a resist film-coated substrate to be processed is cooled in a very gentle curve.

By the way, the inventors focused on the relationship between the cooling rate of the resist and the sensitivity of the resist, and as a result of various tests and research, they found that although the sensitivity of the resist slowly cooled by the conventional process over a long time rOiJ is low, the resist We found that the sensitivity of resists that are rapidly cooled after prebaking is dramatically improved.

[Purpose of the invention]

An object of the present invention is to provide a method and apparatus for forming a resist pattern, which improves the sensitivity of the resist to electromagnetic waves or particle beam irradiation and shortens the time required to form the resist pattern.

[Summary of the invention]

An overview of the resist pattern formation process according to the present invention @
Shown in Figure 3. First, a resist is applied onto a substrate to be processed, and then the resist is baked (prebaked). The process up to this point is the same as the conventional process.

Next, the resist is rapidly cooled, and then a resist pattern is formed by selectively irradiating the resist with electromagnetic waves in a predetermined wavelength range or particle beams with B energy, and developing and rinsing it. It is something to do.

Note that rapid cooling of the resist at a maximum cooling rate of 0.8"07 seconds or more is suitable for sufficiently improving resist sensitivity.

〔Effect of the invention〕

According to the present invention, the sensitivity of a resist to electromagnetic waves or particle beam irradiation can be dramatically improved.

In addition to shortening the exposure time by improving sensitivity, the present invention also shortens the resist cooling process, which conventionally took a long time after pre-bake, by rapidly cooling it, thereby significantly shortening the time from pre-bake to the end of exposure. It becomes possible. For example, the conventional processing speed of about 10 sheets per hour can be increased to about 300 sheets per hour, greatly improving work efficiency.

[Embodiments of the invention]

Examples of the present invention will be specifically described below.

First, the following experiment was conducted according to the resist pattern forming process according to the present invention shown in FIG. A small drop of various resists dissolved in a solvent is dropped from a jet nozzle onto a substrate to be processed placed on a rotating table, using a well-known spin coating method.)
A predetermined film thickness was applied.

After that, the resist film is repainted in an oven (
Pre-bake) Shida. After the prebaking was completed, the resist film and the substrate were rapidly cooled by, for example, being immersed in a water tank containing pure water at room temperature as a cooling liquid. In this case, the resist film exhibited the characteristics shown in FIG. 4 as the temperature decreased from the pre-bake temperature to near room temperature. Here, the temperature of the resist was measured by bringing a thermocouple into contact with the resist.

Next, the substrate with the resist film was placed on a rotating table and spin-dried. As a result of irradiating a sufficiently dried resist film with an electron beam at an acceleration voltage of 20 and then developing and rinsing it, we achieved a dramatic improvement in resist sensitivity compared to conventional methods, as shown in the table below. It was confirmed that

The sensitivity in Table 1 was determined from the sensitivity curve shown in FIG. 5, which shows the relationship between the exposure amount and the remaining resist film thickness after development. Curve 1 shows the sensitivity curve of the conventional example, and curve 2 shows the sensitivity curve of the present invention.

FIG. 6 is a characteristic curve diagram showing how the resist sensitivity changes when the cooling rate of the resist is changed using the data in Table 1 above. Curve 1 is the case when resist C is used, and curve 2 is the case when resist D is used. As is clear from this figure, the maximum cooling rate of the resist is 0.8
Rapid cooling at a rate of °C/second or higher can significantly improve sensitivity compared to conventional methods.

In particular, when the cooling rate is 10° C./sec or higher, sensitivity can be improved several times more than conventional techniques.

The main focus of the present invention is to rapidly cool the resist film after prebaking to a temperature lower than the glass transition temperature (Tf) of the resist, its refrigerant, cooling means, and subsequent drying. The method and the like are not particularly limited to the above-mentioned embodiments. For example, as the coolant, in addition to pure water, a liquid or gas that does not dissolve or react with the resist can be used. In that case, it is effective to select a material with as large a specific heat as possible, as well as the substrate material to which the resist film will be deposited.

The resist solvent, developer, pre-bake temperature, etc. are not limited to the above-mentioned examples, and it was confirmed that high sensitivity can be achieved with various known materials and temperatures. That is, the present invention is applicable not only to positive type resists but also to negative type resists. Regarding the resist exposure method, similar results can be obtained by using, in addition to the above-mentioned electron beam, particle beams with a predetermined energy such as light beams, X-rays, and ion beams, and electromagnetic waves in a predetermined wavelength range.

Next, an example of an apparatus suitable for carrying out the method of the present invention will be explained with reference to FIG. The apparatus shown in FIG. 7' fully automatically performs a series of steps from resist coating to the substrate to before Ri irradiation.

First, the substrate 1 to which resist is applied is placed on the vacuum chuck 2.
The spindle is placed on the rotary sample stage 3 for coating. --Ichireru. Next, the substrate 1 is placed on the belt conveyor 5 by the vacuum chuck 2 and introduced into the pre-bake auto t76. A heater 7 for pre-baking is provided inside the oven 6, and a low-speed belt conveyor 8 for taking in the substrate 1 is also provided below the heater 7. When the substrate 1 conveyed by the belt conveyor 5 enters the open 6, it is transferred to the belt conveyor 8, which slowly passes through the open 6 and is prebaked by the heater 7 at a predetermined temperature for a predetermined time. . The prebaked substrate 1 is transferred to a belt conveyor 9, further conveyed, and introduced into a rapid cooling mechanism 10 where it is protected.

That is, the substrate 1 transported by the belt conveyor 9 is transferred to a transport mechanism 11 that can move up and down and left and right, and is immersed in pure water 13, which is a liquid refrigerant, in a cooling tank 12, and is rapidly cooled. The cooled substrate 1 is transferred to a belt conveyor 14 by a transport mechanism 11 and placed on a rotating sample stage 15 for spin drying. Substrate 1 dried by rotating the sample stage 150 times
is transferred to a belt conveyor 17 by a vacuum chuck 16 and carried out. The substrate 1 with the resist film thus obtained is patterned through a predetermined exposure process and development/rinsing process. Thermocouples 40 and 41 are used to measure the temperature of the resist. An infrared radiation thermometer can also be used to measure temperature.

Incidentally, the rapid cooling mechanism 10 is not limited to the immersion type shown in FIG. 7, but can be modified to include a spray set, a shower set, or a cooling plate type, for example.

FIG. 8 shows a rapid cooling mechanism using the spray method, in which the substrate 1 is placed on a rotating sample stage 20, and while being rotated,
A liquid or gas refrigerant is sprayed from an upper jet nozzle 21. The cooled substrate 1 is placed in a vacuum chuck 22
It will be transferred to

FIG. 9 shows a rapid cooling mechanism for a shower set, in which substrates 1 transported by a belt conveyor 9 are placed in a cooling chamber of a multi-hole cooling device 23 by a low-speed belt conveyor 5.
The refrigerant 27 stored in the liquid refrigerant chamber 26 is transferred to the partition wall 2.
The water is ejected from the multi-hole nozzle 29 of No. 8. The cooled substrate 1 is transferred to a belt conveyor 14 and rotated to a rotating sample stage 15.
After drying, it is transferred by a vacuum chuck 16 to a belt conveyor 17 and conveyed. Gas can also be used as the refrigerant 27. In that case, the rotating sample stage 15 is inappropriate.

, j Figure 10 shows a cooling plate type rapid cooling mechanism. The substrate 1 is conveyed by the belt conveyor 31.
While at fb, the cooling plate 3 close to the upper substrate 1
2, it is designed to be rapidly cooled.

Note that the belt conveyor 31 may be stopped and the cooling plate 32 may be brought into contact with the substrate 1.

In the rapid cooling of the substrate 1 by the apparatus described above in FIGS. 7 to 10, it is possible to cool the resist film at a uniform temperature as a whole, and the sensitivity of the resist is Not only the improvement but also the precision of the layered pattern can be obtained.

That is, the inventors used conventional technology to stand a substrate on a support stand and let it cool naturally, and measured the temperature distribution over the entire surface of the substrate (resist film) at a certain point in time during the natural cooling by infrared rays. As a result of checking with a thermometer, it was found that the upper center of the substrate 1 to be processed has a high temperature and is difficult to cool down, while the temperature below and the peripheral area is low and is easily cooled. The reason why such a temperature distribution occurs is that the substrate to be processed is placed on a support stand during natural cooling, so natural convection due to heat dissipation tends to occur upward along the substrate surface, and the bottom of the substrate is It is conceivable that heat is easily absorbed by the support stand.

Furthermore, the inventors focused on the relationship between the temperature distribution of the substrate (resist film) and pattern accuracy, and measured the dimensions of the formed pattern at several temperature measurement points, and found that each pattern should have the same dimensions. It was confirmed that the temperature distribution of the substrate (resist film) and the size distribution of the formed pattern corresponded to each other.As shown in Figs. It has been found that if the temperature of the film is lowered while the temperature distribution is uniform, the pattern dimensions will be less uneven and the accuracy will be improved.

[Brief explanation of the drawing]

Fig. 1 is a block diagram schematically showing the conventional resist pattern forming process, Fig. 2 is a characteristic diagram showing the temperature change of the substrate to be processed after prebaking in the conventional process, and Fig. 3 is a diagram showing the temperature change of the substrate to be processed after prebaking in the conventional process. FIG. 4 is a block diagram schematically showing the resist pattern forming process; FIG. 4 is a characteristic diagram showing how the temperature of the substrate to be processed changes due to rapid cooling of the resist in the present invention;
The figure is a sensitivity curve diagram in the conventional resist pattern forming method and the present invention, FIG. 6 is a characteristic diagram showing the relationship between resist cooling rate and sensitivity according to the present invention, and FIG. 7 is an apparatus suitable for implementing the present invention method. FIGS. 8 to 10 are explanatory diagrams showing various modifications of the rapid cooling mechanism. 1...Substrate, 4...Resist jet nozzle, 6...
Open, 5@8.9.14"15-25.31...
Belt conveyor, 11...Transportation mechanism, 12...Cooling tank, 3, 15, 20...Sample rotating table, 21...Cooling jet nozzle, field...Cooling device, 32...Cooling plate . Figure 1 Figure 3 Figure 2 Figure 5 At4 Figure 4

Claims (1)

[Scope of Claims] (1) After coating a resist on a substrate, the resist is baked, and the resist is selectively irradiated with electromagnetic waves in a predetermined wavelength range or particle beams with a predetermined energy, and developed. A method for forming a resist pattern, characterized in that the method includes a step of rapidly cooling the resist after baking the resist and before irradiating the electromagnetic wave or particle beam. . (2) The resist pattern forming method described in the patent is characterized in that the maximum cooling rate of the resist is 0.8' (!/sec or more). (3) The rapid cooling of the resist is A method for forming a resist pattern according to claim 1, characterized in that the method is carried out in a liquid or gas that does not cause dissolution or reaction. The method for forming a resist pattern as set forth in claim 3, characterized in that <1i month, shadow y$. (5) The rapid cooling gas is low temperature nitrogen gas or The method for forming a resist pattern according to claim 3, characterized in that the liquid or gas for rapid cooling is applied to the resist by a dipping method, a spray method, or a shower method. A method for forming a resist pattern according to claim 1, characterized in that the resist pattern is brought into contact with the resist pattern. The apparatus used includes a mechanism for applying a resist onto a substrate, a mechanism for housing the substrate and pre-baking the resist, a mechanism for rapidly cooling the pre-baked resist, and a resist coating mechanism. A resist pattern forming apparatus comprising: a mechanism for transporting the substrate to the rapid cooling mechanism via the prebake mechanism.