JPH0786155A - Fabrication of semiconductor device - Google Patents

Abstract

PURPOSE:To secure a semiconductor substrate flatly without contaminating the surface thereof by forming a positive resist layer on a supporting body, heating the main surface of an opaque semiconductor substrate while applying pressure onto the resist layer, exposing the semiconductor substrate from the main rear surface thereof and developing the resist layer. CONSTITUTION:A holding body, i.e., a fixing glass plate 21, and a retaining glass plate 31 are spin coated with positive resists 22, 32. An opaque semiconductor substrate 11 is then applied to the resist 22 while opposing the main surface side 14 thereto. It is further spin coated with a positive resist 23. The semiconductor substrate 11 is then sandwiched between the fixing glass plate 21 and the retaining glass plate 31 while opposing the rear surface side 15 of the semiconductor substrate 11 to the resist 32 on the retaining glass plate 31. The laminate is then pressed and baked. It is then exposed from the rear side and developed thus removing the resist entirely except the resist region 24. This method allows flat securing of the semiconductor substrate and the fixing glass plate without leaving any bubble therebetween.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of fixing a surface of a semiconductor substrate to a surface of a holder such as a glass plate for performing a manufacturing process in manufacturing a semiconductor device such as a Gunn diode.

[0002]

2. Description of the Related Art As an example of a conventional process for manufacturing a semiconductor device, a process for manufacturing a gun diode having a PHS (Plated Heat Sink) structure will be described with reference to FIG.

As shown in FIG. 1A, GaAs, In
A thickness 1 consisting of an active layer and a high-concentration impurity layer sandwiching the active layer on the front main surface of a substrate 1 made of P or the like and having a thickness of about 400 μm.
The operating layer 2 having a thickness of about 0 μm is epitaxially grown. AuGe / Ti / Pt / plating Au is sequentially laminated on the operating layer 2 to form the metal layer 3.

Next, as shown in FIG. 1B, the metal layer 3
The side is fixed to the holding plate 4 with the wax 5, and is scraped from the back main surface side of the substrate 1 to have almost the thickness of the operating layer 2. After that, as shown in FIG. 1C, an electrode 6 corresponding to a target element shape (for example, a circular shape having a diameter of 80 μm) is formed on the scraped back main surface of the substrate 1 to form the electrode 6. The portion of the operating layer 2 that has not been formed is removed by anisotropic etching such as RIE (reactive ion etching) to form a mesa-shaped element portion. Then, the metal layer 3 removed from the holding plate 4 was cut and disassembled into each element, and then each element was packaged.

[0005]

In such a process, the metal layer 3 side of the substrate 1 is fixed to the holding plate 4 with the wax 5 in order to carry out the subsequent processes such as cutting the back main surface side of the substrate 1. ing. However, with such fixation,
The non-fixed surface of the substrate is contaminated by the wax, the substrate cannot be fixed flat due to the presence of air bubbles in the wax, and the wax is softened and dissolved, so that the subsequent cleaning solvent, process temperature and other process conditions There was a problem such as being limited.

The present invention solves the above-mentioned drawbacks, and an object of the present invention is to provide a method capable of fixing the surface of a semiconductor substrate flat without contamination of the subsequent process conditions. It is provided.

[0007]

According to the method of manufacturing a semiconductor device of the present invention, in the step of fixing the other main surface of the semiconductor substrate to the holder in order to perform the manufacturing process on one main surface of the semiconductor substrate, a) forming a positive resist layer on the holder,
(b) The other main surface of the opaque semiconductor substrate is heated while applying pressure to the resist layer, and (c) the resist layer is developed by exposing from one main surface of the semiconductor substrate.

[0008]

According to the present invention, since the positive type resist layer is heated under pressure, no air bubbles remain in the resist layer and at the same time, the opaque substrate is removed from the opposite side of the resist layer. By exposing and developing the resist layer, the resist layer other than between the substrate and the holder can be selectively removed.

Therefore, by a simple process, the substrate does not remain on the unfixed surface of the substrate and the substrate can be flatly fixed on the holder, which is most suitable for the mass production process of semiconductor devices.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A manufacturing process of a Gunn diode which is an embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 2, an operating layer 12 of about 10 μm in thickness composed of an active layer and a high-concentration impurity layer sandwiching the active layer is epitaxially grown on the front main surface of a substrate 11 of InP having a thickness of 400 μm. AuGe / Ti / Pt / plated Au on the operating layer 12
To sequentially form a metal layer 13. The plated Au layer has a thickness of 30 μm or more and can block ultraviolet and visible light.

The front main surface side 14 of the substrate 11 is fixed to a flat surface of a fixing glass plate 21 which is a holder. First,
Fixing glass plate 21 and pressing glass plate 3 equivalent thereto
1 are prepared, and novolak resin-based positive photoresists (MP1400, manufactured by Microposit Co., Ltd.) are provided on their surfaces.
-27) is spin-coated (rotation speed: 3000 rpm) so that the thickness becomes 3.5 μm. As shown in FIG. 3, the front main surface side 14 of the substrate 11 is attached to the resist 22 of the fixing glass plate 21 so as to face it. Further, the same positive photoresist is spin-coated (rotation speed: 3000 rpm) on the resist 22 and on the side surface of the substrate 11 and the back main surface 15 with a resist 23 having a thickness of 3.5 μm. At this time, bubbles may enter between the substrate 11 and the resist 22 on the fixing glass plate 21. After that, the resist 32 on the pressing glass plate 31 is opposed to the back main surface side 15 of the substrate 11,
The glass plate 21 for fixing and the glass plate 31 for pressing the substrate 11
Sandwich between them.

As shown in FIG. 4, the substrate 11 is sandwiched between the fixing glass plate 21 and the pressing glass plate 31, and a weight (not shown) is placed on the pressing glass plate 31,
Pressurize at a pressure of 500-600 g / cm ² ,
Bake at 80 ° C for 30 minutes. By this step, bubbles between the resist 22 and the substrate 11 are removed, and the substrate 11 can be fixed flat. The resist 2 from the pressing glass plate 31 side
² , 23 and 32 are exposed under the condition of 500 mJ / cm ² . The resists 22, 23, 32 are developed by a developing solution (manufactured by Microposit,
The resist region 2 between the substrate 11 and the fixing glass plate 21 is developed by developing with MP450 diluted).
It is possible to remove all the resist except for the portion 4 in FIG. At the same time, the pressing glass plate 31 is also removed. afterwards,
Post-baking is performed at 100 ° C. for 30 minutes in order to strengthen the fixation by the resist region 24 between the substrate 11 and the fixing glass plate 21.

After that, the back main surface side 15 of the substrate 11 is ground to obtain almost the thickness of the operating layer 12. As shown in FIG.
An operating layer 1 in which a circular electrode 16 having a diameter of 80 μm is formed on the scraped back main surface of the substrate 11 and the electrode 15 is not formed
The two portions are removed by anisotropic etching by RIE (reactive ion etching) to form a mesa-shaped element portion 17. Then, by removing the resist region 24 between the metal layer 13 and the fixing glass plate 21 with a release agent (acetone),
The metal layer 13 removed from the fixing glass plate 21 is cut and disassembled into each element, and the Gunn diode is completed.

According to the above steps, the simple steps are as follows:
The resist on the surface of the substrate 11 is completely removed by exposure and development, and since no bubbles remain between the substrate 11 and the fixing glass plate 21, the resist can be fixed flat. Therefore, even when the back main surface of the substrate 11 is fixed and the anisotropic etching is performed, there is no variation in the thickness between the elements, and the temperature and the chemical stability are stable as compared with fixing by wax. It is possible to manufacture under the best conditions without considering the temperature conditions of anisotropic etching and surface contamination.

[Brief description of drawings]

FIG. 1 is a cross-sectional view for explaining a manufacturing process of a PHS structure Gunn diode which is a conventional technique.

FIG. 2 is a cross-sectional view for explaining a process on the front main surface side of the substrate 11 in the example of the present invention.

FIG. 3 is a cross-sectional view for explaining a step of disposing the substrate 11 on the fixing glass plate 21 in the example of the present invention.

FIG. 4 is a cross-sectional view for explaining a step of sandwiching the substrate 11 between the fixing glass plate 21 and the pressing glass plate 31 in the example of the present invention.

FIG. 4 shows resists 22 and 23 according to an embodiment of the present invention.
It is sectional drawing for demonstrating the exposure process of 32.

FIG. 5 is a cross-sectional view for explaining a step after the substrate 11 is fixed to the fixing glass plate 21 in the example of the present invention.

[Explanation of symbols]

 11 substrate 12 operation layer 13 metal layer 14 front main surface side 15 back main surface side 16 electrode 17 element part 21 fixing glass plate 22 resist 23 resist 24 resist region 31 pressing glass plate 32 resist

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[Procedure amendment]

[Submission date] November 22, 1993

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 4

[Correction method] Change

[Correction content]

[Figure 4]

[Procedure amendment]

[Submission date] April 22, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is a cross-sectional view for explaining a manufacturing process of a PHS structure Gunn diode which is a conventional technique.

FIG. 2 is a cross-sectional view for explaining a process on the front main surface side of the substrate 11 in the example of the present invention.

FIG. 3 is a cross-sectional view for explaining a step of disposing the substrate 11 on the fixing glass plate 21 in the example of the present invention.

FIG. 4 is a cross-sectional view for explaining a step of sandwiching the substrate 11 between the fixing glass plate 21 and the pressing glass plate 31 in the example of the present invention.

FIG. 5 is a cross-sectional view for explaining a step after the substrate 11 is fixed to the fixing glass plate 21 in the example of the present invention.

[Explanation of reference numerals] 11 substrate 12 operation layer 13 metal layer 14 front main surface side 15 back main surface side 16 electrode 17 element portion 21 fixing glass plate 22 resist 23 resist 24 resist region 31 pressing glass plate 32 resist

Claims (1)

[Claims] 1. In a step of fixing another main surface of the semiconductor substrate to a holder so as to perform a manufacturing process on one main surface of the semiconductor substrate, (a) forming a positive resist layer on the holder. (B) heating the other major surface of the opaque semiconductor substrate while applying pressure to the resist layer, and (c) exposing the one major surface of the semiconductor substrate to develop the resist layer. Of manufacturing a semiconductor device.