JPH07211628A - Substrate heater - Google Patents

Abstract

PURPOSE:To attain pattern dimensions with high in-plane uniformity by providing a heating means, a hot plate having a concentric recess, a temperature detecting means, and a temperature regulating means thereby heating a substrate uniformly. CONSTITUTION:A hot plate 1 is heated by means of a heater 2. Temperature of the hot plate 1 is detected by means of a thermocouple and regulated to a constant level by means of a temperature regulator 4. A photomask is mounted on the surface of the hot plate 1 and brought into tight contact therewith or a gap of about 0.1mm is set by inserting a spacer, e.g. a ball. Central temperature of the photomask can be lowered by making a recess in the center of the hot plate 1. The temperature drop depends on the diameter and the depth of recess an in case of a 152 mm square photomask of 6.3 mm deep, a recess of 50 mm diameter and 0.2 mm depth restrains the temperature rise from average temperature within 0.5 deg.C which is significantly low as compared with a case having no recess. Furthermore, temperature distribution can be improved signiticantly by employing a conical recess in the center.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating device for heating thick substrates such as photomasks for semiconductors and liquid crystal panels.

[0002]

2. Description of the Related Art A semiconductor photomask will be described as an example. The latest semiconductor photomask is formed by sputtering a chromium film of about 1000 angstrom on a glass substrate of 152 mm square and a thickness of 6.3 mm, applying a resist on it, drawing a pattern with an electron beam drawing device, and then developing the resist. Then, the chrome film is etched and the resist is removed to complete the process.

Due to the miniaturization of patterns accompanying the improvement in the degree of integration of LSIs, chemically amplified resists have been developed and put into practical use as resists having high dry etching resistance and highly accurate resist patterns. A typical product is SAL601 from Shipley.

After the chemically amplified resist is drawn with an electron beam,
Baking is performed at about 110 ° C. to amplify the sensitivity of the resist. Since the pattern size changes depending on the temperature uniformity of the upper surface of the photomask during baking, it is necessary to perform baking at a uniform temperature over the entire surface.

FIG. 3 is a vertical sectional view of a conventional substrate heating apparatus.

The heating plate 1 is heated by the heater 2. Thermocouple 3
The temperature of the hot plate 1 is detected by, and the temperature is adjusted by the temperature controller 4 to a constant temperature, for example, 110 ° C. Photomask 10 is hot plate 1
It may be placed on the upper surface of the device, but may be placed in close contact or may be placed with a gap of about 0.1 mm by inserting a spacer such as a ball.

When a photomask having a size of 152 mm square and a thickness of 6.3 mm is heated by this conventional heating device, the photomask 1
Since the material of No. 0 is glass having poor heat conductivity, even if the temperature of the hot plate is uniform, the temperature of the upper surface of the photomask 10 is concentrically distributed with the center temperature being 2-3 ° C. higher than the average temperature. . Therefore, there is a defect that the resist sensitivity in the central portion is increased, the apparent exposed portion size is increased, and the in-plane uniformity of the photomask 10 is deteriorated.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a substrate heating apparatus capable of uniformly heating a substrate and obtaining a pattern dimension with good in-plane uniformity.

[0009]

The present invention is characterized in that it comprises a heating means, a hot plate having concentric recesses, a temperature detecting means, and a temperature adjusting means.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. Figure 1
a is a longitudinal sectional view of the first embodiment of the substrate heating apparatus of the present invention,
FIG. 1b is a plan view thereof.

The temperature of the hot plate 1 is adjusted in the same manner as in FIG. By forming the depression 5 in the central portion of the heating plate 1, the temperature of the central portion of the photomask 10 can be lowered. The temperature decreases depending on the diameter and depth of the depression, but
In the case of a photomask with a square size of 6.3 mm and a thickness of 6.3 mm, the diameter is 5
The temperature at the center when the depth was 0 mm and the depth was 0.2 mm was 0.5 ° C. higher than the average temperature, and was significantly smaller than when there was no dent.

FIG. 2a is a vertical sectional view of a second embodiment of the substrate heating apparatus of the present invention, and FIG. 2b is a plan view thereof.

By adding one or a plurality of concentric ring-shaped depressions 7 and 8 in accordance with the temperature distribution of the photomask 10, a more uniform substrate heating apparatus can be obtained.

Further, by making the central depression a conical depression 6, it is possible to give the depression a temperature gradient, so that the temperature distribution of the photomask 10 is further improved.

In the above description, the case where the depression of the hot plate is circular is described, but the present invention is not limited to this, and it is obvious that the present invention can be realized even with a polygonal depression. .

In the above description, the case where the resist is a chemically amplified resist is described, but the present invention is not limited to this, and it is apparent that the present invention can be applied to a resist which requires a uniform baking temperature in exactly the same manner. Is.

In the above description, the photomask is taken as an example, but it is obvious that the same can be realized with a semiconductor substrate or a liquid crystal panel substrate.

[0018]

As described above, the present invention has the following effects. By heating the substrate uniformly, a pattern dimension with good in-plane uniformity can be obtained.

[Brief description of drawings]

FIG. 1a is a longitudinal sectional view of a first embodiment of a substrate heating apparatus of the present invention.

FIG. 1b is a plan view of the first embodiment of the substrate heating apparatus of the present invention.

FIG. 2a is a vertical sectional view of a second embodiment of the substrate heating apparatus of the present invention.

FIG. 2b is a plan view of the second embodiment of the substrate heating apparatus of the present invention.

FIG. 3 is a vertical sectional view of a conventional substrate heating apparatus.

[Explanation of symbols]

1 ... Hot plate, 2 ... Heater, 3 ... Thermocouple, 4 ... Temperature controller,
5, 6, 7, 8 ... Dimples, 10 ... Photomask.

Claims (4)

[Claims] 1. A substrate heating apparatus for heating a substrate, comprising: a heating means, a heating plate having concentric circular depressions, a temperature detecting means, and a temperature adjusting means. 2. The substrate heating apparatus according to claim 1, wherein the depression is circular with a depth of 0.05 to 0.5 mm. 3. The substrate heating apparatus according to claim 1, wherein the recess has a conical shape with a depth of 0.05 to 0.5 mm. 4. The substrate heating apparatus according to claim 1, wherein the recess is a ring having a depth of 0.05 to 0.5 mm.