JPH0320048A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To eliminate a crack at a thin substrate having a through hole by forming the through hole at the substrate of a thick state, filling only the hole, and etching the whole surface. CONSTITUTION:Photoresist 4 is selectively formed on a substrate 3, with the photoresist 4 as a mask by substrate 3 is deleted by etching, and a hole piercing the substrate 3 is formed. Then, the photoresist 4 is removed, the whole substrate surface is coated with photoresist 5, the whole surface is exposed, developed, and the photoresist 5 remains only in the hole formed previously. Thereafter, the whole substrate surface is etched to remove the remaining photoresist 5. Thus, it can prevent the substrate 3 from cracking, and a thin semiconductor substrate having a through hole with uniform area of the through side is obtained.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a method for manufacturing a semiconductor device.

In conventional high frequency semiconductor devices, it is necessary to quickly ground the ground portion in order to reduce the source inductance to some extent. For this reason, a method is used in which the back surface of the element is used as a grounding section, a through hole is formed in the substrate to directly connect this to the source section, and this through hole is filled with metal to ground the source section at the shortest distance. Furthermore, in devices that handle large amounts of power, there is a demand for the thickness of the substrate to be as thin as possible in order to improve heat dissipation. In order to meet this need, conventionally, as shown in FIG. 2a, the semiconductor substrate 1 is made into a thickness of about 30 μl to 40 μl as shown in FIG. 2b by mechanical polishing or wet etching, and then As shown in C, through holes were formed by dry etching using a photoresist or the like as a mask.

Problems to be Solved by the Invention However, as described above, if a process for forming through holes is performed after the substrate is made thin, cracks will occur in the substrate due to mechanical strain, thermal strain, etc. during the process.

Means for Solving the Problems In order to solve the above problems, in the manufacturing method of the present invention, a through hole is formed in a substrate that is thicker than before, and then only the inside of the through hole is filled and the entire surface is etched. By this, a thin substrate with through holes is obtained.

Effect: In the above-mentioned method, the substrate is thicker and stronger than the conventional method at the stage of forming the through-hole, so that cracking of the substrate does not occur during the step of forming the through-hole.

Embodiment FIG. 1 is a sectional view of a process showing an embodiment of the present invention.
This figure shows the process of forming a through hole in an aAs substrate.

As shown in FIG. 18, a photoresist 4 is selectively formed on the semi-insulating G&▲S substrate 3 with a thickness of, for example, 120 μl, and then as shown in FIG. 1b, cc4 2F 2 and ▲
Active ion etching (
RIB) using photoresist 4 as a mask.
a▲S Cut the substrate to form a hole that passes through the substrate. After removing the photoresist 4, a positive-type 7-year-old photoresist 6 is applied to the entire surface of the substrate, and the entire surface is exposed and developed.
As shown in Figure 1C, only inside the previously formed through hole,
Leave photoresist 5. Thereafter, the entire surface of the substrate is wet-etched using a phosphoric acid-based etching solution as shown in FIG. 1d. By removing the remaining photoresist 6, as shown in FIG. 1, through-holes are selectively formed.
A GaAg substrate with a thickness of 30 μm is obtained. In this example,
A 120 μl thick GaAs substrate was subjected to R treatment using a mixed gas of COl2F2 and ▲r using a photoresist as a mask.
Dry etching was performed using IB, and wet etching was performed using a phosphoric acid-based etching solution on a 30 μm thick casing, but the same method can be used for substrates such as Si and InP. The first mask is not limited to photoresist, but may also be a dielectric film such as SiN film or Si02 film, or a metal film, and dry etching and wet etching methods are also available.
The method is not limited to the method of this embodiment.

As described above, the present invention has the following advantages: After forming a through hole in a semiconductor substrate which is thicker than conventional ones, the inside of the formed through hole is filled with a substance other than the substrate, and the entire surface of the substrate is wetted. By etching, it is possible to prevent the substrate from cracking and to obtain a thin semiconductor substrate that has through holes with a uniform area on the penetrated side, and has great practical effects.

[Brief explanation of the drawing]

1A to 1E are cross-sectional views showing the process of forming a thin semiconductor substrate having through-holes according to the manufacturing method of the present invention, and FIGS.
FIG. 3 is a cross-sectional view showing the shape and process of a thin semiconductor substrate having a through hole according to a conventional manufacturing method. 1...Semiconductor substrate, 2...Photorenst, 3...Semi-insulating GaAs substrate, 4...
...Photoresist, 5...Photoresist.

Claims (1)

[Claims] A method for manufacturing a semiconductor device, comprising the steps of embedding a through hole in a semiconductor substrate provided with a through hole, and then thinning the semiconductor substrate.