Substrate heating method

Details Substrate heating method Substrate heating method

1996-12-19

2002-08-20

Padgett, Marianne (Department: 1762)

Coating processes

Direct application of electrical, magnetic, wave, or...

Polymerization of coating utilizing direct application of...

C427S504000, C427S510000, C427S552000, C427S553000, C427S555000, C430S198000, C430S330000, C430S346000, C430S942000

Reexamination Certificate

active

06436482

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a substrate heating apparatus, a substrate heating method, a semiconductor integrated circuit device, a photomask and a liquid-crystal device.
2. Description of the Related Art
As a heating method of a conventional substrate heating apparatus, an oven-type heating method or a hot-plate-type heating method is employed. A substrate heating apparatus having an oven-type heating method of these methods is designed to indirectly heat a workpiece to be heated, for example, a substrate in a heating atmosphere inside a heat insulation chamber which serves also to shield heat on the precondition that a plurality of substrates are heated at a time.
On the other hand, in recent years, a substrate heating apparatus employing a hot-plate-type heating method has been generally used due to the necessity of forming what is commonly called “inline processing” with other apparatuses for the purpose of reducing the adhesion of particles onto a substrate and without human intervention.
An example of a conventional substrate heating apparatus employing a hot-plate-type heating method will now be described with reference to the schematic view of FIG.
1
.
As shown in
FIG. 1
, a substrate heating apparatus
101
basically comprises a heater
111
and a heater block
112
formed on the heater
111
.
In order to heat a substrate
121
by using the substrate heating apparatus
101
, the substrate
121
is placed on the heater block
112
and the heater block
112
is heated by the heater
111
so as to heat the substrate
121
from the rear surface of the substrate
121
. Therefore, the substrate
121
is heated via the heater block
112
by the heater
111
.
In recent years, resist materials have been improved in order to form patterns finer than those of the known art. For example, a resist material utilizing a catalytic reaction during heating time has been developed, and such a resist material has been used in a semiconductor device manufacturing process. In such resist materials, acid generated in a resist material due to irradiation of light or irradiation of a charged particle beam reacts with a functional group having a high reactivity to acid due to heating after the irradiation, and the solubility characteristic of the resist material with respect to the developing solution varies, thus forming a pattern. The above-mentioned resist is generally called a chemical amplification-type resist.
However, use of a chemical amplification-type resist causes temperature conditions for heating after exposure or after the charged particle beam is irradiated to affect the reaction speed. For example, as shown in the relation view of
FIG. 14
between the line width variation amount of a pattern and heating temperature, it can be seen that the temperature conditions during the heating period cause the line width of the pattern to vary. Therefore, presence of a temperature distribution on the surface of the substrate brings about undesirable results in high-precision pattern formation.
In a conventional oven-type substrate heating apparatus, since the heating chamber is opened and closed when a heating process is started, the reproducibility of temperature and the controllability of the temperature inside the heating chamber are low. Also, since the substrate is indirectly heated, the temperature distribution under the substrate surface is considerably unfavorable. Further, also in the conventional substrate heating apparatus employing a hot-plate-type type heating method, the temperature distribution of the substrate surface is unfavorable. For these reasons, it is not possible to form high-precision patterns.
An example of the above will be described below with reference to FIG.
15
. In
FIG. 15
, the vertical axis shows differences from the reference dimension (line width=1.0 &mgr;m) of the pattern, i.e., dimensional variations of the pattern, and the horizontal axis shows measurement positions with respect to the effective area (a 110 mm square) in a photomask.
The patterns measured in the example are formed by the processes described below. That is, an acid catalytic reaction-type resist is coated on a glass substrate having a thickness of 6 mm and heated to remove a resist solvent. Then, the resist film is irradiated with an electron beam, after which the glass substrate is heated by the substrate heating apparatus of a hot-plate-type heating method. Then, a development process is performed to form a pattern.
The dimensional variations of the resist pattern in this case were 3&sgr;=0.045 &mgr;m.
It can be seen in
FIG. 15
that (a) the dimensional variation varies from a positive variation to a negative variation toward a particular direction (the front side in the drawing in this example). That is, since heating is performed only from the rear surface of the glass substrate in the substrate heating apparatus of a hot-plate-type heating method, the pattern dimension distribution depends upon the parallel relation between the heater block and the substrate. For this reason, when the parallel relation is poor, variations in pattern dimensions having directivity occur.
Also, (b) a large variation of the pattern dimension occurs near the outer peripheral portion of the substrate. This is caused by the heat loss which occurs due to the convection of air.
Such phenomena as the above-described (a) and (b) appear conspicuously in cases where thermal conductivity is as low as in a glass substrate and the thermal capacity increases with the thickness of the substrate. In particular, in the manufacture of photomasks, it is practically impossible to obtain patterns having high dimensional precision.
Further, (d) also in a silicon substrate having relatively high thermal conductivity, problems similar to those described above have been reported [47th Symposium On Semiconductor Integrated-Circuits, Proceeding Papers (1994), Yamamoto et al., P60], presenting a considerable problem in a manufacturing process.
SUMMARY OF THE INVENTION
The present invention has been achieved to solve the above-described problems. It is an object of the present invention to provide a substrate heating apparatus and a substrate heating method which excel in achieving uniformity of pattern dimension and which excel in reducing dimensional variations in the portion under the substrate surface, and to provide a semiconductor integrated circuit device, a photomask, and a liquid-crystal display device, in each of which each substrate is heated by the substrate heating apparatus.
To achieve the above-described objects, according to the present invention there is provided a substrate heating apparatus, a substrate heating method, a semiconductor integrated circuit device, a photomask and a liquid-crystal device.
More specifically, the substrate heating apparatus used in a manufacturing process for semiconductor devices, heats a substrate before or after irradiation of light for forming a pattern by using a photosensitive material formed on a substrate, or before or after irradiation of a charged particle beam for forming a pattern by using a material that is sensitive to charge particles, formed on a substrate. The substrate heating apparatus comprises a first heater which is a heat source for heating a substrate from the obverse surface thereof and a second heater which is a heat source for heating the substrate from the rear surface thereof, wherein the temperatures of the first and second heaters can be set individually.
The surface of the first heater on the substrate must be spaced from the surface of this substrate, and the space is set to be 10 mm or smaller. It is preferable that a recessed portion be formed on at least a part of the surface of the first heater on the substrate side. Further, the second heater comprises a third heater which constitutes the central portion of the second heater and the area adjacent to the central portion of the second heater, and a fourth heater disposed around the side peripheral portion of t

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