JPS60117625A - Forming method of resist pattern and processing device for resist - Google Patents

Abstract

PURPOSE:To improve sensitivity to electromagnetic waves or the projection of particle beams of a resist by baking a resist film at a temperature of the glass transition temperature or higher of the resist before development treatment after exposure and rapidly cooling the resist film up to a temperature of the glass transition temperature or lower of the resist. CONSTITUTION:Substrates 1 with resist films after exposure are passed in an oven 4, and baked at a fixed temperature for a fixed time by a heater 5. The substrates 1 completely baked are transferred to a belt conveyor 3c, carried and introduced to a cooling mechanism 6. The substrates 1 being carried are transferred to a carrying mechanism 7, which can be rolled upward and downward and right and left, and dipped in pure water 9 as a liquid refrigerant in a cooling tank 8, and cooled rapidly. The cooled substrates 1 are transferred to a belt conveyor 3d, and placed on a rotary sample base 10 for spin drying. The dried substrates 1 are transferred to a belt conveyor 3e by a vacuum chuck 11 and received in a cassette 2b in succession, and the substrates 1 obtained in this manner are developed and rinsed in a predetermined manner, thus forming resist patterns.

Description

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

[Technical Background of the Invention and Problems Therewith] As the integration density of semiconductor elements, including VLSIs, increases, finer and more accurate pattern forming techniques are required.

On the other hand, in order for such pattern forming technology to be used on a mass production line, high speed is required, and resists with higher sensitivity are expected.

FIG. 1 is a flowchart showing a resist pattern forming process according to the prior art. First, after spin-coating a resist onto a substrate to be processed, the solvent is removed and the substrate is placed in an oven at a predetermined temperature (Tb) depending on the type of resist to improve adhesion to the substrate. Perform baking (pre-bake).

Thereafter, the resist film-coated substrate taken out of the oven is allowed to cool naturally in clean air, and is cooled to about room temperature over a period of 20 to 30 minutes.

With a resist film that has been completely cooled? I! ! C for the processed substrate
, electromagnetic waves in a predetermined wave area with a predetermined dose depending on the type of resist, such as ultraviolet light or a particle beam of a predetermined energy;
For example, exposure is performed by selectively emitting an electron beam 11L. Thereafter, a desired resist pattern is formed through a development process. FIG. 2 shows how the temperature of the substrate to be processed 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 present inventors focused on the relationship between the cooling rate of the resist and the sensitivity of the resist, and as a result of research, the sensitivity of the resist that was slowly cooled over a long period of time using the conventional process was low, but that We have found that the sensitivity of cooled resist i can be dramatically improved, and have proposed a method of increasing resist sensitivity by rapidly cooling after pre-beta.

Furthermore, as a result of extensive experimentation and research, the inventors have found that even with resists that have undergone conventional pre-baking and natural cooling, the resist's glass transition temperature T (a temperature exceeding + We have found that the sensitivity can be significantly increased by rapidly cooling after baking.Also, regardless of the thermal history of the film after pre-baking, the above-mentioned method is applied again before development. It has also been found that rapid cooling after baking at a temperature exceeding Tg causes a significant increase in sensitivity.

[Object of the Invention] An object of the present invention is to provide a resist pattern forming method that can improve the sensitivity of a resist to electromagnetic waves or particle beam irradiation and shorten the time required to form a resist pattern, and a resist processing apparatus for realizing the method. It is about providing.

[Summary of the Invention] The present invention involves coating and forming a resist film on a substrate, prebaking, and then selectively irradiating the resist film with electromagnetic waves of a predetermined waveform or particle beam of a predetermined energy to form a desired resist]
In the method for forming a resist pattern, in which a resist pattern is formed by exposing a pattern to light and then developing it, after the exposure and before the development treatment, the resist]
- A method in which the film is beta (pre-development baked) at a temperature higher than the glass transition humidity of the resist, and then the resist I film is rapidly cooled to a temperature lower than the glass transition temperature of the resist. .

Further, the present invention provides a resist processing apparatus for realizing the above method, which includes several baking units for heating and baking a resist exposed with a desired pattern to a temperature equal to or higher than the glass transition temperature of the resist, and the beta resist It is constructed with a cooling mechanism that rapidly cools the film to below the glass transition temperature of the resist.

That is, in the resist pattern forming process according to the present invention, as shown in FIG. 3, a resist is first applied onto a substrate to be processed, the resist is baked (prebaked), and then electromagnetic waves in a predetermined wavelength range are applied to the resist. Alternatively, a particle beam of a predetermined energy is selectively irradiated. The process up to this point is the same as the conventional process. Next, the resist is heated to a temperature exceeding its glass transition temperature, baked, rapidly cooled, and developed and rinsed to form a resist pattern.

Note that rapid cooling of the resist at a maximum cooling rate of 0.8 [° C./sec] or more is suitable for sufficiently improving resist sensitivity.

[Effects of the Invention] According to the present invention, the sensitivity of a resist to electromagnetic waves or particle beam irradiation can be dramatically improved. Further, by shortening the exposure time due to improved sensitivity, it becomes possible to significantly shorten the time required to form a resist pattern.

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.

Example of f 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. Various resists dissolved in a solvent were dropped onto a substrate to be processed placed on a rotary table using a jet nozzle and coated to a predetermined thickness by a well-known spin coating method. Thereafter, the resist film was baked (prebaked) in an oven. Next, after irradiating with an electron beam at an accelerating voltage of 20 [keV], the resist film and the substrate were baked before development at a temperature exceeding the glass transition temperature of the resist. After a predetermined period of time, the resist film and the substrate were cooled under the conditions shown in Table 1. The rapid cooling shown in Example 1 was performed by immersing the resist sensitivity immediately after the pre-development bake together with the substrate in a water tank containing pure water at room temperature. Here, the temperature of the resist was measured by bringing a thermocouple into contact with the resist. Thereafter, as a result of development and rinsing, as shown in Table 1, it was confirmed that a dramatic improvement in resist sensitivity was achieved compared to conventional methods.

The sensitivity in Table 1 was determined from the sensitivity curve shown in FIG. 5 showing the relationship between the exposure aperture and the remaining resist film thickness after development. Here, the curve P shows the sensitivity curve of the conventional example, and the song IQ shows the sensitivity curve of the present invention.

FIG. 6 is a characteristic curve diagram showing how the resist sensitivity changes when the resist cooling rate is changed using the data in Table 1 above. Curve R is the case when resist C is used, and curve S is the case when resist D is used. As is clear from this figure, the maximum cooling rate of the resist is 0.8[
If the cooling speed is more than 'C/sec], a significant improvement in sensitivity can be achieved compared to the conventional method. In particular, when the cooling rate is 10 ['C/sec] or higher, sensitivity can be improved several times more than in the past.

Incidentally, the main focus of the present invention is the resist Ill after baking before development.
The purpose is to rapidly cool the resist until the temperature passes through the glass transition temperature (T(+)) and falls below it.The refrigerant, cooling means, and subsequent drying method are as follows:
The invention is not particularly limited to the embodiments described above. 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. Liquid Freon is a compatible refrigerant.

Low-humidity nitrogen gas, chlorofluorocarbon gas, etc. are available. Also, the type of resist and the substrate material fl on which the resist film is deposited.

The resist solvent, developer, prebaking temperature, etc. are not limited to those in the above-mentioned examples, and it was confirmed that high sensitivity as in the examples can be achieved with various known materials. In addition to the above-mentioned electron beam, there are also light beam exposure methods for the resist.

The same results can be obtained using particle beams with a predetermined energy such as X-rays and ion beams, or N magnetic waves in a predetermined wavelength range.

Next, an example of a resist processing apparatus suitable for carrying out the method of the present invention will be described with reference to FIG. M7. 7th
The device in the figure shows the resist film (substrate with resist film) after exposure.
The process of beta-cooling and cooling is carried out fully automatically.

First, the resist film coated substrate 1 after exposure is placed in a cassette 2a in advance.
They are placed on the belt conveyor 3a under a predetermined conveyance sequence and introduced into the beta oven 4 one after another. A heater 5 for baking is provided inside the oven 4, and a low-speed belt conveyor 3b for conveying the resist film coated substrate 1 is provided below the heater 5.

After entering the oven 4, the group 1 transported by the belt conveyor 3a is transferred to the belt conveyor 3b, and is slowly passed through the oven 4 by the belt conveyor 3b, and heated by the heater 5 for a predetermined time.

Baked at a predetermined temperature. Substrate 1 on which the beta has been completed
is transferred to the belt conveyor 3C, further conveyed, and introduced into the cooling mechanism 6. That is, the substrate 1 transported by a bell conveyor 3C is transferred to a transport mechanism 7 that can move vertically and horizontally, and is immersed in pure water 9, which is a liquid refrigerant, in a cooling tank 8, and is cooled at an n-speed. The cooled substrate 1 is transferred to the belt conveyor 3d by the transport mechanism 7 and placed on the rotating sample stage 10 for spin drying.The substrate 1 dried by the rotation of the sample stage 10 is transferred to the belt conveyor 3e by the vacuum chuck 11. The resist film coated substrate 1 thus obtained is subjected to a prescribed development and rinsing process to form a resist pattern. 128 and 121) are resist films. It is a thermocouple for measuring the temperature of. An infrared radiation thermometer may be used for temperature measurement. In the latter case, the humidity of the substrate can be accurately determined without contact.

Note that the cooling mechanism 6 is not limited to the immersion type shown in FIG. 7, and may be modified in various ways, such as a spray type, a shower set, or a cooling plate type.

Is Figure 8 cold fiI scooping using the spray method? M is shown, the substrate 1 is placed on the 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
Transported by.

FIG. 9 shows the cooling mechanism of a shower set, in which the substrate 1 transported by the belt conveyor 3C is placed in a low-speed belt conveyor 25 in the cooling chamber 24 of the multi-hole cooling device 23.
The cold 127 stored in the liquid refrigerant chamber 26 is transferred to the partition wall 2.
The liquid is ejected from the multi-hole nozzle 25 of No. 8. The cooled substrate 1 is transferred to the conveyor 3d and placed on the rotating sample stage 1.
0, and then transferred to a belt conveyor 3e by a vacuum chuck 11 and carried out. Gas can also be used as the refrigerant 27. In that case, the rotating sample stage 10 and vacuum chuck 11 become unnecessary.

FIG. 10 shows a cooling plate type cooling system.

While the substrate 1 is being conveyed by the belt conveyor 31,
A cooling plate 32 close to the upper substrate 1 ensures uniform cooling. Furthermore, belt conveyor 31
Alternatively, the cold iJI plate 32 may be brought into contact with the M plate 1.

[Brief explanation of the drawing]

Fig. 1 is a flowchart 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 baking in the conventional process, Fig. 3 4 is a flowchart schematically showing the resist pattern forming process according to the present invention, FIG. 4 is a dimensional characteristic diagram showing the temperature change of the substrate to be processed due to rapid cooling of the resist 1 according to the present invention, and FIG.
FIG. 6 is a characteristic diagram showing the relationship between the resist resist pattern formation rate and sensitivity according to the present invention, and FIG. 7 is a sensitivity curve diagram for the resist pattern forming method according to the conventional method and the present invention. Figures 8 to 10 are schematic configuration diagrams showing the features of a suitable resist processing device.
It is a figure for explaining the modification of J1c structure. 1...Substrate with resist film, 2a, 2b...Cassette l
-13a to 3e...Belt conveyor, 4...Oven, 5...Heater, 7...Transport mechanism, 8...Cooling tank, 9...Liquid refrigerant, 10...Substrate rotating table , 11
...Vacuum chuck, 12a, 12b...Thermocouple, 2
1... Refrigerant jet nozzle, 22... Vacuum chuck, 2
4...Cooling room, 25...Belt conveyor, 26...
・Liquid refrigerant chamber, 27... Refrigerant, 28... Partition wall, 29
...Porous nozzle, 31...Belt conveyor, Applicant's representative Patent attorney Takehiko Suzue Continued from page 1 @ Inventor Usu 1) Kinya 0 Inventor Shigemitsu Bunmei Kawasaki-shi Saiwai-ku Komukai Toshiba-cho 1 Tokyo Shibaura Inside the Tamagawa Factory of Tokyo Shibaura Electric Co., Ltd. 1 Komukai Toshiba-cho, Saiwai-ku, Kawasaki City Inside the Tamagawa Factory of Tokyo Shibaura Electric Co., Ltd.

Claims (1)

[Claims] (1) After coating and forming a resist film on a substrate and prebaking, the resist film is selectively irradiated with electromagnetic waves in a predetermined wavelength range or particle beams with a predetermined energy to form a desired resist pattern. In the method of forming a resist pattern by exposing and then developing, the resist film is baked at a temperature above the glass transition temperature J of the resist after the exposure and before the development. Bake before development)
Then, the resist pattern forming method is characterized in that the resist film is rapidly cooled to a temperature lower than the glass rolling temperature of the resist. (2) In the rapid cooling of the resist film after the pre-development baking The method for forming a resist pattern according to claim 1, characterized in that the maximum cooling rate is 0.8 ['C/sec] or more. (3) Rapid cooling of the resist film after the pre-development baking The method for forming a resist pattern according to claim 1, characterized in that the cooling is performed with a liquid or gas that does not dissolve or react with the resist. (4) The rapid cooling liquid is , water, or liquid fluorocarbon. (5) The rapid cooling gas is low-temperature nitrogen gas or fluorocarbon gas. A method for forming a resist pattern according to claim 3. (a) The rapid cooling liquid or gas is brought into contact with the resist film by a dipping method, a spray method, or a shower method. The method for forming a resist pattern according to claim 3. (7) The rapid cooling of the resist film after the pre-baking step comprises:
2. The method of forming a resist pattern according to claim 1, wherein the method is carried out by bringing a cooling plate into contact with or close to the resist or the substrate. (8) A baking mechanism that bakes a resist film on a substrate on which a desired resist pattern has been exposed by selective irradiation with an electromagnetic wavelength of a predetermined wavelength or a particle beam of a predetermined energy at a temperature equal to or higher than the glass transition temperature of the resist. A resist processing apparatus comprising: a cooling mechanism that rapidly cools the baked resist film to a temperature below the glass transition temperature of the resist.