JPH04335551A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To provide a method for manufacturing a semiconductor device, in which a dicing step of a semiconductor wafer having a conductive film formed on its rear surface is smoothly performed and to provide a mounting structure of an optical module having excellent noise resistance. CONSTITUTION:A step of forming a groove on a rear surface of a semiconductor wafer 5 along a scribing line, a step of covering the rear surface having the formed groove and forming a conductive film 1 in the groove G, and a step of cutting the film 1 formed in the groove G by dicing the wafer 5 having the formed film 1 along the scribing line from the front surface, are provided.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device by dicing a semiconductor wafer having a conductive film formed on its back surface.

0002

[Prior Art] Semiconductor materials are generally brittle materials, so the edges of chips are easily chipped. Therefore, dicing blades are also made of materials and structures that are optimal for cutting brittle materials ("Dicing", pp. 42- 51, Semiconductor Packaging Technology Handbook (Science Forum)).

By the way, when manufacturing a semiconductor device with a metal film formed on the back surface, the metal film is generally formed on the back surface of the semiconductor wafer, and the back surface metal film is formed along the scribe line on the front side of the semiconductor wafer. Dice together with the membrane. Microwave devices and power devices are known as semiconductor devices with a metal film formed on the back side. Microwave devices reduce the conductor resistance of the skin effect in microwaves by forming a relatively thick metal film on the back side. (“Microwaves and Metal Plates”, pp.14-
21, Microwave, Abe, University of Tokyo Press), power devices reduce thermal resistance by forming a thick metal film on the back side of a thin wafer (“Thermal Resistance of FETs”, pp. 77) -81, Compound Semiconductor Device Handbook (Science Forum)).

FIG. 4 is a cross-sectional view showing a state in which a semiconductor wafer 2 having a metal film 1 formed on its back surface is fixed on a tape 3 and cut with the above-mentioned dicing blade 4.

[0005]

[Problems to be Solved by the Invention] As shown in the figure, since the metal film 1 formed on the back surface is generally ductile, the metal film 1 escapes from the dicing blade 4 without being cut during dicing, and the semiconductor There was a problem that the wafer 2 was not divided.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for manufacturing a semiconductor device that does not interfere with the dicing process of a semiconductor wafer having a conductive film of metal or the like formed on the back surface.

[0007]

[Means for Solving the Problems] In order to achieve the above object, the present invention includes a process of forming grooves on the back surface of a semiconductor wafer along scribe lines, and covering the back surface on which the grooves are formed with a conductive material. The method includes a step of forming a conductive film in the groove, and a step of cutting the conductive film formed in the groove by dicing the semiconductor wafer on which the conductive film is formed along the scribe lines from the front surface.

[0008]

[Operation] According to the method of manufacturing a semiconductor device according to the present invention,
Before the dicing process, a groove is formed on the back surface of the semiconductor wafer along the scribe line, and the conductive film is cut within the groove. In this case, since the depth of the groove contributes to the amount of cut that can be made by the dicing blade, it becomes possible to make a cut that exceeds the amount of relief of the conductive film in the dicing process.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. In the description, the same elements are denoted by the same reference numerals, and redundant description will be omitted. FIG. 1 is a process diagram showing a method for manufacturing a GaAs IC as a semiconductor device according to an embodiment, and FIG. 2 is a flowchart showing the process.

First, a semiconductor element is formed on the surface of the GaAs substrate 5 (step 101). Next, a resist material is applied to the back surface of this GaAs substrate 5 by spin coating (step 102) to form a resist film 6 on the entire back surface (FIG. 1(a)). Next, this resist film 6 is exposed and developed (step 103) to form a resist pattern having openings A along the scribe lines (FIG. 1(b)). In this case, the width of opening A is 100 mm thick.
For example, 10 to 150 μm GaAs substrate 5
It can be set to about 50 μm. Using this resist pattern as a mask, the GaAs substrate 5 is subjected to RIE (
Dry etching such as reactive ion etching is performed (step 104). Thereafter, the resist film 6 is removed from the back surface of the GaAs substrate 5. Figure 3 (
1A is an overall view showing the back side of the GaAs substrate 5 after the resist film 6 has been removed, and FIG. 1B is an enlarged view of a portion thereof. As shown in the figure, by this dry etching, a groove G having a substantially trapezoidal cross section is formed on the back surface of the GaAs substrate 5 along the scribe line (FIG. 1(c)). Next, the resist pattern is removed and metal is deposited (step 105), and a metal film (conductive film) 1 is formed on the back surface of the GaAs substrate 5 (FIG. 1(d)). After that, this GaAs
A tape 3 with a film thickness of 50 to 100 μm is adhered to the back surface of the substrate 5 (FIG. 1(e)), and the GaAs substrate 5 is divided into chips from the surface along the scribe line with a dicing blade 4 (FIG. 1(f)). , step 106).

As described above, in the manufacturing method according to this embodiment, the metal film 1 is formed inside the groove G formed before the dicing process.
Since the metal film 1 is cut, the dicing blade 4 can follow the escape of the metal film 1 deposited on the bottom of the groove G, and the metal film 1 is reliably cut.

It should be noted that the present invention is not limited to the above embodiments. For example, etching methods are not limited to RIE,
Dry etching other than RIE, wet etching (
chemical etching, etc.).

[0013] Normally, the back metal of GaAs IC (operating at several GHz) is made of Ti with a thickness of 500 to 1000 angstroms.
It is formed by sputtering or vapor depositing Au to a thickness of 1500 to 3000 angstroms. However, especially in the case of microwave devices and power devices, since Au is further deposited with a thickness of 2 to 50 μm by electrolytic plating, the back metal becomes even thicker, and a wide and deep groove is required. In this case, a groove with a large width and depth can be formed by wet etching using an etchant with a high etching rate, for example.

Furthermore, in the above embodiment, semiconductor elements are formed on the front surface of the wafer, and then grooves are formed on the back surface along the scribe lines, but semiconductor elements may be formed on the front surface after forming the grooves. .

[0015]

[Effects of the Invention] In the present invention, since the conductive film is cut within the grooves formed before dicing, the dicing blade can follow the escape of the conductive film, without causing any trouble to the dicing process. Semiconductor devices can be manufactured.

[Brief explanation of drawings]

FIG. 1 is a process diagram showing a method for manufacturing a semiconductor device according to an embodiment of the present invention using longitudinal cross-sectional views of a semiconductor wafer.

FIG. 2 is a flowchart showing a method for manufacturing a semiconductor device according to an embodiment of the present invention.

[Figure 3] Ga after removing the resist film of the semiconductor wafer
FIG. 3 is a plan view showing the back side of the As substrate.

FIG. 4 is a longitudinal cross-sectional view showing a dicing state in a conventional method for manufacturing a semiconductor device.

[Explanation of symbols]

1...Metal film 2...Semiconductor wafer 3...Tape 4...Dicing blade 5...GaAs substrate 6...Resist film A...Aperture G...Groove

Claims (1)

[Claims] 1. A method for manufacturing a semiconductor device manufactured by dicing a semiconductor wafer having a conductive film formed on the back surface, comprising: forming a groove on the back surface of the semiconductor wafer along a scribe line; A conductive film is formed in the groove by depositing a conductive material on the back surface of the groove, and dicing the semiconductor wafer on which the conductive film is formed along the scribe line from the front surface. A method for manufacturing a semiconductor device, the method comprising: cutting a conductive film formed by cutting the conductive film.