JPS6043828A - Formation of resist pattern - Google Patents

Abstract

PURPOSE:To contrive accomplishment of high sensitivity and stabilization of sensitivity of a resist film when exposing and developing processes are performed by a method wherein a plate to be processed is arranged horizontally in a housing vessel having a cooling gas introducing part and a gas sucking part, and cooling gas is supplied into the housing vessel in the state of laminar flow, thereby enabling to rapidly cool the resist film uniformly. CONSTITUTION:A resist mask is formed on a blank mask 13, and they are housed in a cassette 14 in such a manner that the resist film is facing upward. Cooling N2 gas is supplied into a high pressure reservoir 1, and a low pressure reservoir 6 is maintained at a decompressed state using a vacuum pump 7. After the resist film located on the blank mask in the cassette has been prebaked, the blank mask 13 is set in the tube main body 10 of an expanded tube 5 together with the cassette 14. The cooling N2 gas in the high pressure reservoir 1 is supplied to the expanded tube 5 in a rectified state utilizing the sucking action of the low pressure reservoir 6, and the resist mask on the blank mask 13 of the expanded tube 5 is rapidly cooled.

Description

[Detailed description of the invention] [Technical field of invention] The present invention relates to a method for forming a resist pattern.

[Technical background of the invention]

As the degree of integration of semiconductor devices, including VLSIs, increases, there is a need for microstructure and high-fi master turn formation technology. For this reason, the permissible dimensional accuracy is extremely strict, and in the most advanced fields, dimensional accuracy of 3σ≦0.1 μm (where σ indicates the variation with respect to the average dimensional value of the wafer) within a 6-inch mask or 5-inch wafer. The name is starting to be requested. In addition, in order to be used on a mass production line, it is necessary to suppress dimensional variations between masks or wafers to 3σ≦0.15μm, and on the other hand, in order to enhance the domestic production effect, a highly sensitive resist is required. At the same time, sensitivity control is required to make the sensitivity suitable for the exposure apparatus (energy irradiation apparatus) used.

By the way, the following methods have been conventionally adopted for forming register tops and turns. First, a resist is applied onto a plate to be processed (for example, a mask substrate) by a spin coating method or a dipping method. Next, the lettuce on the substrate is heated at a predetermined temperature (Tb) using heating means such as an oven or a heat source. After baking for a predetermined period of time, the resist film-coated plate is allowed to cool naturally at room temperature and pressure for about 20 to 30 minutes to about room temperature.

Next, the resist film on the cooled substrate is exposed to light at a predetermined exposure amount suitable for the resist, and is further subjected to predetermined development and rinsing treatments to form a renost pattern.

[Problems with background technology]

However, in the conventional method, the highly sensitive resist is
, it is difficult to have the desired dimensional accuracy due to poor eating habits.I゛1
Unfortunately, since resists with high resolution have low sensitivity, there is a problem in that the high throughput required in mass production lines cannot be obtained. Furthermore, it is difficult to use the same resist for the sensitivity tone and contrast of Lennost, and it can only be used under conditions that are restricted in terms of exposure and process conditions. I couldn't. In fact, there was a difference in the sensitivity of the resist film on the plate to be processed after prebaking, making it difficult to form a highly accurate Renost pattern.

[Purpose of the invention]

The present invention provides a method and an apparatus for increasing the sensitivity of a resist, stabilizing the sensitivity, and making it possible to select arbitrary sensitivity conditions, thereby forming highly accurate resist patterns with good reproducibility. This is what I am trying to do.

[Summary of the invention]

The inventors of the present invention have conducted extensive research on the differences in the dimensions of resist patterns on plates to be processed using conventional methods. When the plate is placed vertically, isotherms of different temperatures TI and T2 r are shown in Figure 1.
It was determined that this is caused by the occurrence of T3 (Tt>T2>T3). However, FIG. 1 &'i shows the state at a certain time during cooling of the plate to be processed, and changes moment by moment as time passes. In fact, as a result of precisely measuring the size distribution of the Rennost film on the plate to be processed having the isothermal line shown in Figure 1 after exposure and development, it was found that there is a strong correlation between the size distribution and the temperature distribution. I found out something.

Furthermore, when the plate to be treated is left to cool naturally, the cooling rate when the plate is placed in a vertical position is as shown in Fig. 2. It has been found that a lower portion cooled at a cooling rate as shown by curve B occurs.

In fact, when we investigated the sensitivity of the Lennost film portion on the plate to be processed that had been cooled using curve A shown in Figure 2, we found that the sensitivity characteristic was that of curve A' as shown in Figure 3; Impression of the Lennost film part on the processed plate cooled by curve B 1
B= indicates the sensitivity outside the curve B' shown in FIG. 3, and it has been found that there is a strong correlation between the cooling rate and the sensitivity characteristics, and this is the cause of the difference in dimensions.

From the above, we found that the conventional technology does not control the cooling rate during the cooling process, so the sensitivity fluctuates depending on the cooling conditions, which makes it difficult to form highly accurate resist patterns. Ta.

Therefore, the present inventors considered that the sensitivity characteristics of Renost are correlated with the cooling rate after baking, and that variations in sensitivity occur due to unevenness in the cooling rate. After baking (pre-baking) at a high temperature, the plate to be processed is placed horizontally in a container having a cooling gas introduction part and a gas suction part, and suction is performed from the front iiQ suction part side to supply cooling gas from the introduction part into the container. The resist film on the plate to be processed was uniformly and rapidly cooled by supplying the resist film in a laminar flow state. As a result, it is possible to achieve high sensitivity and stabilize sensitivity in the exposure and development processes, and by controlling the temperature of the cooling gas, the sensitivity conditions for the same resist can be extremely high.
The same resist can be used to meet the most easily controllable sensitivity conditions of exposure equipment and other equipment, and can also be used to create high-precision resists.
We have discovered a method that can reproducibly and quantitatively form curved turns.

That is, the present invention provides a method in which a resist pattern is formed by applying lenost on a plate to be treated, baking it, cooling it, and further performing a silting treatment and a development process, in which the plate to be treated after baking is exposed to a cooling gas. The resist film on the plate to be processed is disposed horizontally in a container having a gas suction section and a gas suction section, and suction is performed from the suction section side, and cooling gas is supplied into the container from the introduction section in a rectified state. 1. To cause rapid cooling.
1″f mark.

The plate to be processed may be, for example, a mask substrate, a wafer, or various semiconductor films, insulating films, or metal films on the wafer. You can praise those coated with I'IG.

As the above-mentioned renost, for example, a photoresist, a far-ultraviolet-sensitive renost, an ME gonad-sensitive renost, an XT9-sensitive resist, a highly accelerated X-ray-sensitive resist, an ion beam-sensitive resist Mq k can be applied.

The cooling gas used for cooling the resist film on the plate to be processed may include, for example, nitrogen gas, alcoin gas, or fluorocarbon gas at an arbitrary temperature setting.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

Embodiment FIG. 4 is a schematic diagram of a cooling device used in the resist/gut pattern forming process according to the present invention, FIG. 5 is a sectional view of a main part of the same device, and FIG. It is a sectional view along +t7 holly. 1 in the figure is the cooling gas force 1. This is a high-pressure reservoir into which high-pressure cooling gas is introduced through the inlet pipe 2. A first valve 31 and one end of an expansion tube 5 serving as a container with tapered ends are connected to the lower part of the high-pressure reservoir 1 via a first valve 31 and a dust removal filter 4. The other end of the expansion tube 5 is connected to a low pressure reservoir 6 via a second valve 32. This low pressure reservoir 6 is provided with a vacuum, J? The reservoir 6 is provided with an intake pulp 8 for bringing the inside of the reservoir 6 to atmospheric pressure after use.

1. As shown in FIGS. 5 and 6, the expansion tube 5 has a rectangular cylindrical tube body 10 having a hollow portion filled with a heat insulating material 9 such as glass wool, and a tube body 10 at both ends of the body 10. Theno-shaped tube parts 111 and 112 are detachably attached,
It is made up of a rectifying network 12 provided in the passage section of the tube body 1θ on the side of the high pressure 1 connector 1.

Next, a method for forming a rennost gastern using the cooling device described above will be explained.

First, a 0.6 μm thick resist was formed by spin coating an FB resist (1') trimethyl methacrylate at Tg=100° C. on a blank mask. Continuing,
A blank mask was placed in a cassette with the resist film facing upward.

Continuing on, the above-mentioned No. 41ffi - No. 1 of the cooling device shown in FIG. The 20th nozzle valve 31 r32 is closed, and the high pressure reservoir 1 is supplied with cooled N2 gas at 10° C. under the condition of f 3 kg/Qn 2, and the low pressure nozzle 6 is fed to the vacuum mashing pump 7 F) 10-” torr.Then, the resist film on the blank mask in the cassette was baked by de-IJ at 170°C, for example, and then immediately heated as shown in Figures 4 to 61''. Set the blank mask 13 into the cassette 14@, the tube body 10 of the expansion tube 5, and close the valve 31.

32 to open the suction action of the low pressure reservoir 6 (reservoir 1,
6), the cooling N2 gas in the high-pressure reservoir 1 was supplied to the expansion tube 5 in a rectified state, and the Lennost film on the blank mask 13 of the expansion tube 5 was rapidly cooled. After this, each cassette of the blank mask was taken out from the main body of the expansion tube, and exposed to an electron beam at an acceleration of 11 and a pressure of 20 keV.
I BT Guno" J71 years old Developing a 13 minute song with liquid crystal (25℃) (114 strokes, IAA rinse solution (liquid temperature 25℃)
A rinsing process was performed for 30 seconds to form a Renost pattern on the blank mask.

However, when we investigated the resist sensitivity of the method of this example and a method similar to the example (comparative example) except that rapid cooling after baking was not performed, we found that While the exposure amount for the f-ray was 4 μCΔ2 in this example, the light amount for the same f-ray was 0.5 μCΔ2 in this example.
It was found that the sensitivity was dramatically improved.

Further, in the comparative example, it was difficult to form the desired Renost pattern with high precision due to variations in sensitivity within the plane of the blank mask.

On the other hand, in the case of this example, in which the resist film was uniformly and quickly cooled by the cooling device described above, the desired high-precision Renost pattern was formed by uniformizing the sensitivity within the plane of the blank mask. We were able to.

Furthermore, in this example, the flow rate ffj can be adjusted by controlling the temperature of the cooling N2 gas supplied and adjusting the degree of depressurization of the low pressure reservoir.
By performing II control, the sensitivity of the resist film can be increased to 8μ.
c/cn could be varied within the range of 12 to 0.5 μQAm2.

In the above embodiment, the pressure of N2 gas supplied to the high-pressure reservoir was set at 3 to 10 n2, but it may be higher or lower than this, and of course it may be at normal pressure. Furthermore, the degree of vacuum of the low pressure reservoir is not limited to 10 torr.

In the above embodiment, a rectifying network was provided in the expansion tube to improve the rectifying effect, but there is no problem in omitting this.

Further, the method of the present invention is not limited to the case where cooling is performed using the cooling apparatus shown in FIGS. 4 to 6. For example, as shown in FIG. 7, a plurality of partition plates 151 to 15 are arranged horizontally in the vertical direction.
4f: Container I6 inside and a passage 171 in which the partition plates 151 to 154 are partitioned on the left side wall of the container I6.
- 17, the cooling gas introduction pipe 1 is connected so as to communicate with
I. , resist Il1
-\The blank masks 131 to 134 having the resistors 2θ1 to 2θ4 are removed from the support and the resist film is formed on the partition plate 151.
After placing it horizontally so as to be located on the opposite side to 154, suction is performed at a predetermined pressure from the suction tube 19, and the introduction tube 181-
Strongly feed cooling gas from 184 to passages 17□ to 174.
The blank masks 13, - 134 may be rapidly cooled by the cooling gas in a rectified state by directing the cooling gas in a rectified state. According to such a method, a plurality of blank masks can be processed at the same time, and the resist film can also be processed through the passages 171 to 17.
By arranging it on the opposite side from 4, dust adhesion can be reduced.

〔Effect of the invention〕

As described in detail above, according to the present invention, it is possible to stabilize the high sensitivity change and sensitivity of the resist, and to select arbitrary J{&degree conditions. A method for forming turns with good reproducibility can be provided.

[Brief explanation of drawings]

Figure 1 shows the temperature contour lines when the plate to be treated after pre-baking is placed vertically and allowed to cool naturally, and Figure 2 is a diagram showing the temperature contour lines when the plate to be treated after pre-baking is placed vertically and allowed to cool naturally. FIG. 3 is a characteristic diagram showing the relationship between the exposure amount and thickness remaining rate in the resist portion during the different cooling processes shown in FIG. 2, and FIG. Used shoulder J
A schematic diagram showing one form of the device, FIG. 5 shows the main part 1 of FIG. 4:
'J'C view, Figure 6 is N' along the vt-■ line in Figure 5.
The f-plane view and FIG. 7 are schematic diagrams showing another form of the cooling device used in the method of the present invention. 1...High pressure 'J sa', 3 1 r 32...i
Z Ruf, 5... Expansion tube, 6... Low pressure reservoir, etc., 7
. . . Vacuum pump, 9. Insulation material, 10. Pipe body, 12. Rectifier network, 13, 1.9. ~134...Blank mask, 14...Cassette, 15□~154・
...Partition plate, J6...Container, 181-184...Cooling gas introduction pipe, 1g...Suction pipe. Applicant's representative Patent attorney Takehiko Suzue Figure 4 and Figure 5 □□□□□-□□□ Figure 6 Figure 7

Claims (1)

[Claims] (4) Renost is applied onto the plate to be processed, baked, cooled, and further irradiated with electromagnetic waves in a predetermined wavelength range or particle beams with a predetermined energy (hereinafter referred to as exposure), and developed. In the method of forming register tops and turns by processing, the '1JIL metal sheet metal after baking is placed horizontally in a container having a cooling gas introduction part and a gas suction part, and suction is applied from the suction part side to Cooling gas is supplied from the human part into the container in a laminar flow state to register the plate to be processed) #+l
A method for forming a resistor (e) turn, characterized by rapidly cooling the resistor (e). (2) Preliminary control of the temperature of the cooling gas supplied to the container'f: register according to claim 1) Method for forming z4 turns.