JPH06132432A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To obtain a GaAs IC wherein its uniformity and its controllability are excellent by a method wherein a chip isolation groove is formed on the surface of a substrate by an etching operation, the substrate is made thin down to a thickness which does not reach the bottom of the groove from the rear side and a PHS is formed by a vapor deposition method or the like. CONSTITUTION:A surface side of a GaAs substrate 2 on which a semiconductor element part has been formed is etched, a groove for chip isolation is formed, a support sheet 5 is pasted and fixed by using a wax material 4, the rear side is then polished and the substrate is made thin dawn to 30 to 60mum. In addition, an Ni layer 6 and an Au layer 7 as substrate metals to be used as electricity- feeding layers in a plating operation are vapor-deposited, and an Au layer 8 to be used as a PHS is formed by an electrolytic plating operation. A resist pattern 9 is formed, the Au layer 8 is etched and removed along a chip isolation position. Lastly, the Ni layer 6 is etched and removed, the GaAs substrate 2 is etched until the isolation groove is reached, and elements are isolated. Even when an etch rate is irregular, the element part is not damaged and the shape of the surface is not spoiled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high frequency and high power GaAs FET having a plated heat sink (PHS) and a method of manufacturing a semiconductor device such as an IC.

[0002]

2. Description of the Related Art In high-power GaAs FETs and ICs, it is necessary to thinly polish GaAs, which is a substrate, in order to reduce thermal resistance, and to form a metal layer to be a heat sink on the back surface of the substrate. Conventionally, as a method of manufacturing such a GaAs IC, for example, after a semiconductor element portion is formed on the front main surface of a substrate, the back surface of the substrate is polished to a predetermined thickness, and further a metal layer (PHS) to be a heat sink is formed by vapor deposition and plating. ) Is formed, the metal layer at the chip separation position is removed by a photolithography process and an etching process of the metal layer, and GaAs, which is the substrate, is removed by etching from the window portion where the metal layer is removed until the substrate surface is reached. By doing so, a method of separating the chips has been adopted.

A conventional manufacturing method will be described below.
2A to 2H show high-power Ga having a conventional PHS.
It is a figure which shows the manufacturing method of AsIC. In FIG. 1A, 1 is a semiconductor element portion formed on the front surface side of the substrate 2. As shown in FIG. 3B, the substrate 2 is attached and fixed to the support plate 5 using the wax material 4, and the back surface side of the substrate 2 is polished to reduce the thickness to 30 to 60 μm. Further, as shown in FIG. 3C, after dip-etching to clean the surface, Ni6 and Au7 as base metals to be a power feeding layer during plating are deposited. FIG. 3D shows a process of forming Au8, which becomes PHS, on the base metal by electrolytic plating.
After that, as shown in FIG. 7E, a resist pattern 9 for removing Au by etching along the chip separation position is formed.
Is formed, and as shown in FIG. 3F, after etching Au 7 and 8, the resist is removed. Finally, Ni6 is removed by etching as shown in FIG. 9G, and subsequently, GaAs as the substrate 2 is etched as shown in FIG.

[0004]

However, in the above-described conventional manufacturing method, since the end point of GaAs etching, which is the substrate, is difficult to be clearly defined, there are portions in the wafer where chip separation is not completely performed due to variations in etching progress. If the etching occurs, or if the etching time becomes long, in the case of wet etching, side etching progresses, and there is a problem that damage to the element portion on the chip surface and defects such as appearance and shape are likely to occur.

The present invention is intended to solve the above-mentioned problems.
It is an object of the present invention to provide a method for manufacturing a semiconductor device which is excellent in uniformity and controllability of a high-power GaAs IC having HS.

[0006]

In order to achieve this object, a method of manufacturing a semiconductor device according to the present invention provides a chip separation line on a first main surface of a substrate on which a semiconductor element portion is formed with a predetermined width by etching. Forming a separation groove having a depth; and thinning the substrate from a second main surface side of the substrate to a predetermined thickness that does not reach the separation groove bottom formed on the first main surface side. A step of forming a metal layer (PHS) to be a heat sink on the second main surface of the substrate by a method such as vapor deposition, plating and etching, and further etching the substrate from the window portion of the metal layer until reaching the separation groove. And a step of separating the chips.

[0007]

With the above structure, the GaA which is the substrate from the back side
When etching s, it can be used as the etching end point of the GaAs substrate when the etching reaches the groove formed for chip separation, and it corresponds to the variation in the etching progress within the wafer. Even if extra etching time is taken to eliminate insufficient separation, the etching margin will be the depth of the separation groove formed from the surface side in advance. It is possible to manufacture a GaAs IC excellent in uniformity and controllability without causing damages to the element portion on the surface or causing defects such as appearance and shape.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

1 (a) to 1 (j) are process sectional views showing a method of manufacturing a semiconductor device made of a GaAs IC in an embodiment of the present invention. In FIG. 1A, 1 is a semiconductor element portion formed on the substrate surface side, and 2 is a GaAs substrate. FIG. 6B shows a step of forming a resist pattern 3 for forming a groove for chip separation, and FIG. 6C shows a state where the resist is removed after etching. After that, as shown in FIG. 3D, the substrate 2 is attached and fixed to the supporting plate 5 using the wax material 4, and the back surface side is polished to 30 to 30%.
The substrate 2 is thinned to 60 μm. Further, as shown in FIG. 7E, after dip-etching to clean the surface, Ni6 and Au7, which are base metals to be a power supply layer during plating, are deposited. FIG. 6F shows a process of forming Au8, which becomes PHS, on the base metal by electrolytic plating. After that, a resist pattern 9 for etching and removing Au along the chip separation position is formed as shown in FIG. 9G, and then the resist 9 is removed after Au etching as shown in FIG. . Finally, Ni is removed by etching as shown in (i) of the same figure, and subsequently, as shown in (j) of the figure, GaAs which is the substrate 2 is etched until reaching a separation groove formed in advance from the surface side. Then, the elements are separated.

When the chip separation is performed in such a manufacturing process, even if the etching rate of GaAs etching varies, the chip separation can be surely performed without damaging the element portion of each chip or damaging the surface shape. You can That is, in the place where the GaAs etching reaches the groove earliest in the wafer, the side etching progresses until the portion where the etching is latest reaches the groove.
s Excessive etching does not proceed in the depth direction if the width is wider than the width in which etching progresses. Further, even if extra etching is performed to etch in the depth direction, a margin is the depth of the groove before reaching the surface side of the element. Therefore, the chips can be reliably separated from the entire wafer, and the possibility of damaging the element portion and damaging the surface shape can be extremely reduced. In particular, it is effective when performing chip separation by wet etching, which has large etching variations and side etching.

In this embodiment, Au plating, which is a heat sink, is formed on the entire wafer and then separated by etching. However, a resist pattern may be formed after forming a base metal and selective plating may be formed.
As the base metal, in addition to Ni / Au of this embodiment, only Ni, Ti / Au, Ti only, Cr / Au, Cr only, etc. can be considered.

Further, a process of separating the chips by dicing instead of etching can be considered. That is, FIG.
After the process is advanced to (h) or (i), a blade having a blade width narrower than the width of the window portion of the PHS etching reaches the ionization groove previously formed from the back surface side and the support plate. This is a method of dicing to a depth that does not reach Also in this case, since the thickness of the wax material and the depth of the groove are the margins of the dicing depth, chip division may be incomplete or the support plate may be damaged as compared with the case without the separation groove. It is possible to obtain a stable process with extremely low reproducibility and excellent reproducibility.

[0013]

As is apparent from the above description, the method of manufacturing a semiconductor device according to the present invention has a predetermined width and a predetermined width obtained by etching the chip separation line on the first main surface of the substrate on which the semiconductor element portion is formed. A step of forming a separation groove having a depth, and a step of thinning the substrate from a second main surface side of the substrate to a predetermined thickness that does not reach the separation groove bottom formed on the first main surface side. , A step of forming a metal layer (PHS) to be a heat sink by a method such as vapor deposition, plating, etching, etc. in a place where the chip separation groove on the second main surface side is not formed, and from the window portion of this metal layer. And a step of separating the chip by etching or dicing the substrate until it reaches the separation groove, and it is possible to provide a semiconductor device having a PHS structure with excellent reproducibility and uniformity. .

[Brief description of drawings]

FIG. 1 is a process sectional view showing a method for manufacturing a semiconductor device according to an embodiment of the present invention.

FIG. 2 is a process sectional view showing a conventional method for manufacturing a semiconductor device.

[Explanation of symbols]

 1 Semiconductor Element Section 2 GaAs Substrate (Substrate) 3 Resist Pattern 4 Wax Material 5 Support Plate 6 Ni 7 Au 8 Au (Metal Layer as Heat Sink) 9 Resist

Claims (5)

[Claims] 1. A step of forming a separation groove of a predetermined width and depth in a chip separation line on a first main surface of a substrate on which a semiconductor element portion is formed by etching, and using the substrate as a second main surface of the substrate. From the surface side to a predetermined thickness so as not to reach the bottom of the separation groove formed on the first main surface side, and a heat sink by a method such as vapor deposition or plating on the second main surface of the substrate. And a step of forming a resist pattern so that a window of the pattern is opened in a region corresponding to the separation groove formed on the first main surface on the metal layer, and a step of forming the window. A step of removing the metal layer in a portion and a step of separating each chip by etching from the second main surface of the substrate in the region where the metal layer is removed to reach the separation groove. How to manufacture semiconductor devices Law. 2. Instead of the step of separating each chip by etching from the second main surface of the substrate in the region where the metal layer is removed to reach the separation groove, the region along the region where the metal layer is removed is replaced. 2. The method for manufacturing a semiconductor device according to claim 1, wherein a step of dicing the substrate to separate into chips is performed. 3. A step of forming a separation groove of a predetermined width and depth in a chip separation line on a first main surface of a substrate on which a semiconductor element portion is formed by etching, and using the substrate as a second main surface of the substrate. Side, a step of thinning to a predetermined thickness so as not to reach the bottom of the separation groove formed on the first main surface side, and a metal thin film on the second main surface of the substrate by vapor deposition or electroless plating. A step of forming, a step of forming a resist pattern so that the resist covers the region corresponding to the separation groove formed on the first main surface on the metal thin film, and selectively using the resist pattern as a mask A step of forming a metal layer to be a heat sink by plating, a step of removing the metal thin film in this portion by etching after removing the resist, and a substrate in a region where the metal thin film is removed And a step of separating each chip by etching from the second main surface until the separation groove is reached. 4. Instead of the step of separating each chip by etching from the second main surface of the substrate in the region where the metal thin film is removed to reach the separation groove, the metal thin film is removed along the region where the metal thin film is removed. 4. The method of manufacturing a semiconductor device according to claim 3, wherein the step of dicing the substrate to separate into chips is performed. 5. The substrate is arranged so as not to reach the bottom of the separation groove formed on the first main surface side from the second main surface side of the substrate.
The step of thinning to a predetermined thickness is such that after the support plate is attached to the first main surface side of the substrate with a wax material or the like, the substrate is formed from the second main surface of the substrate to the first main surface side. 2. The step of thinning until a predetermined thickness is reached so as not to reach the bottom of the formed separation groove.
3. The method for manufacturing a semiconductor device according to 3 or 4.