JPS5863134A - Resist hardening process and device - Google Patents

Abstract

PURPOSE:To provide the resist hardening process and device improving the yield of surface elastic wave filter etc. by a method wherein the substrate of surface elastic wave filter etc. is heated by means of radiant heat both from the resist coated side of wafer and the opposite side. CONSTITUTION:The part of pallet 2 not covered with wafer 3 loaded on the pallet 2 is heated by radient heat from heat source 1 increasing the temperature thereof. At this time the temperature of the central part of pallet 2 covered with said wafer 3 is also increased by the thermal diffusion due to thermal conduction inside pallet 2. Consequently the under side of wafer 3 is heated heating the contact surface between wafer 3 and resist 4 coated on the wafer 3 i.e. the under side of resist 4. Therefore the evaporation of solvent from under side of resist 4 may be accelerated until the thermosetting film is formed on the surface of said resist 4.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for curing the resist after coating the resist in the step of forming the filter pattern on a wafer serving as a substrate for a surface acoustic wave filter, etc., and its use therein. related to the equipment used.

Surface acoustic wave filters are made by depositing aluminum on top of a single crystal urethane such as lithium niobate.
It is created by forming a desired pattern through processes such as resist coating and curing, exposure, development, resist curing, and etching. Among the above steps, in the resist a cloth curing and resist curing steps, the resist is thermally hardened using a constant temperature bath or a tunnel furnace.

The degree of curing in this resist thermosetting process is determined by controlling the line width and cross-sectional shape of the aluminum pattern when the aluminum pattern as the surface acoustic wave filter is formed through the exposure, development, and etching processes. It becomes a influencing factor. In other words, depending on the degree of heat curing of the resist,
The electrical characteristics of the direct acoustic wave filter are influenced.

It is generally well known that among the above-mentioned devices used for thermal curing of resist, a tunnel furnace is an excellent device for automating the work compared to a constant temperature bath.

However, in tunnel furnaces in which a heat source such as an infrared heater is placed above the wafer and the resist is cured by radiant heat from the heat source, curing proceeds from the surface of the resist. .

Therefore, before the solvent under the resist evaporates, a resist cured film is sometimes formed on the surface of the resist, thereby preventing the evaporation of the solvent. As a result, the area near the bottom of the resist that is in contact with the wafer is not sufficiently cured.
The adhesive strength between the resist and the wafer may not be sufficient.

Therefore, in the past, for example, in the etching process, excessive etching was performed, and as a result, the desired aluminum line width and cross-sectional shape could not be obtained, resulting in poor yields of surface acoustic wave filters, etc. .

SUMMARY OF THE INVENTION An object of the present invention is to provide a resist curing method and an apparatus therefor that eliminate the drawbacks of the prior art described above and improve the yield of surface acoustic wave filters and the like.

The first point of the present invention is that in order to increase the adhesive strength between the wafer and the resist by heating the resist near the bottom, in addition to heating by radiant heat from the resist-coated side of the wafer, heat is also applied from the opposite side of the wafer to the resist-coated side. The point is that we decided to do all the heating.

The second point of the present invention is that, as mentioned in the first point, the device that heats the wafer from the side opposite to the resist-coated side places a pallet with good heat conductivity under the wafer, and heats the wafer by passing the heat through the pallet. : The reason is that heating is performed from the bottom of the wafer.

Hereinafter, the invention will be explained in detail with reference to the drawings.

, 6.

FIG. 1 is a schematic side view showing an embodiment of the resist curing device of the invention, and FIG. 2 is a plan view taken along line 1--2 in FIG.

In these 1, 1 is a heat source such as an infrared heater, 2 is an aluminum pallet whose surface is treated black so as to absorb more radiant heat from the heat source 1, and 3 is placed on the pallet 2. 4 is a resist coated on the wafer 3, and 5 is a pulley belt for conveying the pallet 2 and the wafer 3 placed thereon.

As is clear from FIGS. 1 and 2, in the apparatus according to the present invention, a pallet 2 with a wide surface area for wafers 3 is placed on a pulley belt 5 installed below a heat source 1. The configuration was such that a wafer 6 was mounted.

With the above configuration, the portion of the pallet 20 that is not covered by the wafer 3 mounted on the pallet 2 is exposed to radiant heat from the heat source 1.
The temperature in that area increases, 4.

Ru. Correspondingly, since heat diffusion by heat conduction takes place inside the pallet 2, the temperature also rises in the central portion of the pallet 2 covered by the way -3.

As a result, the wafer 5 is also heated from its lower surface, and the contact surface between the wafer 6 and the resist 4 coated thereon, that is, the lower part of the resist 4 is also heated. Therefore, until a thermosetting film is formed on the surface of the resist 4, evaporation of the solvent from the lower part of the resist 4 is promoted.

As is clear from the above description, if the method and apparatus of the invention are used, the lower part of the resist 4 can be cured extremely well compared to the conventional method, and the adhesive strength between the wafer and the resist can be strengthened. As a result, for example, when forming an aluminum pattern in the etching process, it is almost certain to obtain the desired line width and cross-sectional shape.This has the effect of improving the yield in the manufacturing process of isosurface acoustic wave filters, etc. There is.

[Brief explanation of drawings]

FIG. 1 is a schematic side view showing one embodiment of the resist curing apparatus of the present invention, and FIG. 2 is a plan view taken along line 1--2 in FIG. 1...Heat source 2...Pallet 6...Wafer 4...Resist 5...Pulley belt Representative Patent Attorney Office 7. JP-A-511-631: (4(3) 1st n 2nd prisoner

Claims (1)

Scope of Claims (11) In a resist curing method in which a resist coated on the surface of a wafer is thermally cured by radiant heat from the surface side of the resist, the wafer on the opposite side to the surface coated with the resist A resist curing method characterized in that by heating the back surface, the resist is also heated from the inside and thermally cured by modifying the heat conduction. (2) The resist is applied to the surface of the resist. In a resist curing apparatus having a heat source that irradiates a wafer with heat from its front side and thermally cures the resist from the hardened surface using the radiant heat, a heat absorbing and thermally conductive pallet is provided for mounting the wafer. . A resist curing apparatus, characterized in that the surface &' of the pallet is wider than the surface area of the wafer.