JPH04305925A - Polishing method of semiconductor wafer - Google Patents

Abstract

PURPOSE:To provide the polishing method of a semiconductor wafer, in which no crack is generated in a semiconductor wafer due to the application of local force to one part of the semiconductor wafer and the thickness of the semiconductor wafer can be adjusted accurately. CONSTITUTION:In the polishing method of a semiconductor wafer 7, in which one surface of the semiconductor wafer 7 is polished by relatively displacing a polishing surface plate 6 and the semiconductor wafer 7, the semiconductor wafer 7 is polished in such a manner that wax 10 is arranged on the epitaxial growth surface 9 of the semiconductor wafer 7, and load 4 is applied to the semiconductor wafer 7 through the wax 10.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for polishing semiconductor wafers used for light emitting and receiving elements, etc.

0002

[Prior art] Light emitting diode (LED) element for communication,
Alternatively, a semiconductor laser (LD) element etc. can be an optical fiber,
Alternatively, it is directly connected to an optical element or the like with optical precision. For this reason, the semiconductor wafer constituting such an element is polished and its thickness is adjusted to optical precision. This polishing process is performed on the surface (hereinafter referred to as the non-epitaxial growth surface) opposite to the surface on which the semiconductor layer is formed by epitaxial growth (hereinafter referred to as the epitaxial growth surface).

FIG. 5 shows a semiconductor wafer polishing apparatus 15 that has been conventionally proposed.

The polishing device 15 includes a guide 16 for pressing down the semiconductor wafer 17, a load 18 to be applied to the semiconductor wafer 17, and a polishing plate 1 for polishing the semiconductor wafer 17.
It consists of 9.

In the polishing method using this polishing device 15, a semiconductor wafer 17 is placed on a polishing plate 19, and the semiconductor wafer 17 is placed on a polishing plate 19.
A guide 16 carrying a load 18 is placed on the epitaxial growth surface 20 of No. 7, and the guide 16 applies a pressing force to the semiconductor wafer 17, and the polishing plate 19 whose surface is filled with an abrasive material 22 is rotated to remove the semiconductor wafer. 17 non-epitaxial growth surfaces 21 are polished.

[0006]

However, the method of polishing the semiconductor wafer 17 using the polishing apparatus 15 described above has the following problems.

That is, when a semiconductor layer is formed by a liquid phase epitaxial growth method or the like, growth spots of semiconductor crystals may be formed on the epitaxial growth surface 20 of the semiconductor wafer 17. Figure 6 (a) shows that this growth spot is the epitaxial growth surface 2.
In this example, when the protrusion 23 is formed at the center of the epitaxial growth surface 20, when the epitaxial growth surface 20 is pressed down by the guide 16, the load 1
The force of 8 is not applied evenly to the entire semiconductor wafer 17, but is concentrated only at the location where the protrusion 23 is formed, and the semiconductor wafer 17 is broken centering on the location of the protrusion 23 during the polishing process. A problem had arisen.

Further, as shown in FIG. 6(b), a protrusion 2 is formed at the end of the epitaxial growth surface 20 of the semiconductor wafer 17.
4, the guide 16 will not be placed parallel to the semiconductor wafer 17, and if polishing continues as is, the non-epitaxial growth surface 21 will not be polished parallel to the polishing plate 19, and as a result, the semiconductor wafer 17 will be It was not possible to precisely adjust the thickness. Further, the characteristics of the formed element itself were also deteriorated accordingly.

[0009] Furthermore, in order to solve the above two problems, a polishing method has been proposed in which a spacer is interposed between the semiconductor wafer 17 and the guide 16, but in this case, the thickness of the intervening spacer is While accurate adjustment is required, it is extremely difficult to form spacers having a uniform thickness, and this also complicates the polishing process.

0010

OBJECTS OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and its objects are to prevent cracking of the semiconductor wafer from occurring due to local force being applied to a portion of the semiconductor wafer, and to reduce the thickness of the semiconductor wafer. An object of the present invention is to provide a method for polishing a semiconductor wafer, which allows the polishing of semiconductor wafers to be adjusted with high precision.

[0011]

Means for Solving the Problems The present invention provides a method for polishing a semiconductor wafer, in which one side of the semiconductor wafer is polished by relatively moving a polishing plate and a semiconductor wafer. , a wax is disposed on the non-polished surface of the semiconductor wafer, and a load is applied to the semiconductor wafer through the wax.

0012

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

FIG. 1 is a front view of a polishing apparatus 1 used in the present invention, and this polishing apparatus 1 is composed of a polishing jig 5 and a polishing plate 6. As shown in FIG.

That is, the polishing jig 5 includes a guide 2 for pressing the semiconductor wafer parallel to the polishing plate 6, a wafer paralleling device 3 for arranging the guide 2 parallel to the polishing plate 6, and a semiconductor wafer. It consists of 4 loads. The polishing plate 6 is attached rotatably, for example, so as to be movable relative to the polishing jig 5, and is also configured to be freely detachable from the polishing jig 5.

Hereinafter, this polishing apparatus 1 will be explained using FIGS. 2 to 4.
A method of polishing a semiconductor wafer using the polishing method will be explained.

First, FIGS. 2 and 3 show the process of placing wax on a semiconductor wafer. A semiconductor wafer 7 made of GaAs, InP, etc. is placed on a heating plate 8 made of alumina.
The wax 10 is placed on the epitaxial growth surface 9 of the semiconductor wafer 7 so that the projections 12 (in this example, the epitaxial growth surface 9 is intentionally provided with the projections 12) are covered with the wax 10, and the heating plate 8 is placed on the surface of the semiconductor wafer 7. The wax 10 is softened by the heat of the hot plate 11.

Specifically, the semiconductor wafer 7 is placed on a horizontally arranged heating plate 8, and the semiconductor wafer 7 is placed on a heating plate 8 having a softening point of about 76° C., for example.
, adhesive strength is about 27Kg/cm2, and penetration is 25
°C, 100g, 5sec = 1, 25 °C, 200g, 5s
Electrowax (common name) with ec = 10 is uniformly applied on the epitaxial growth surface 9 of the semiconductor wafer 7, and then this wax 10 is heated for about 30 minutes on a hot plate 11 set at a temperature of about 110°C. Soften.

Next, as shown in FIG. 3, after placing the polishing jig 5 on the heating plate 8 (before this, remove the hot plate 11 or turn off the heating power of the hot plate 11). ), guide 2 with wax 10
The semiconductor wafer 7 is placed on the epitaxial growth surface 9 via the wafer 1, and the wax 10 is cooled and solidified at room temperature for about 30 to 60 minutes while applying a predetermined load 4, and the semiconductor wafer 7 is fixed parallel to the guide 2 by the adhesive force of the wax 10. At this time, the guide 2 is placed parallel to the epitaxial growth surface 9 with high precision by the wafer parallelization device 3, and the magnitude of the load 4 is 0.25 to 0.5 g// to the epitaxial growth surface 9.
Set it so that it is cm2.

Next, the polishing jig 5 with the semiconductor wafer 7 fixed to the guide 2 is placed parallel to the polishing plate 6 whose surface is filled with the abrasive material 13 as shown in FIG. Size 0.5 to 10g/9
The polishing plate 6 is rotated while applying a load 4 of cm2 to polish the non-epitaxial growth surface 14 of the semiconductor wafer 7.

After polishing the non-epitaxial growth surface 14, the polishing jig 5 is placed again on the heating plate 8, and the wax 10 is melted and removed by the heat of the hot plate 11. Finally, the epitaxial growth surface 9 is organically cleaned using trichlene or an alkylbenzene-based organic solvent.

According to the polishing method of this embodiment, even if growth spots of semiconductor crystals are formed on the epitaxial growth surface 9 due to the epitaxial growth method, the growth spots can be removed by wax 10.
Since the guide 2 is covered by the semiconductor wafer 7, the guide 2 can always be placed parallel to the semiconductor wafer 7, and accordingly, the load during polishing can be evenly applied to the entire epitaxial growth surface 9. Therefore, cracking of the semiconductor wafer 7 due to local force applied to a portion of the semiconductor wafer 7 does not occur, and the non-epitaxial growth surface 14 can be polished with high precision.

[0022]

[Effects of the Invention] According to the polishing method of the present invention, wax is placed on the surface of the semiconductor wafer on which the load is applied, and the load is applied to the semiconductor wafer through this wax, so that the polishing method is applied locally to a portion of the semiconductor wafer. This prevents the semiconductor wafer from cracking due to excessive force, and allows the thickness of the semiconductor wafer to be adjusted with high precision.

[Brief explanation of the drawing]

FIG. 1 is a front view of a polishing apparatus of the present invention.

FIG. 2 is a process explanatory diagram illustrating one step of the polishing method of the present invention.

FIG. 3 is a process explanatory diagram illustrating one step of the polishing method of the present invention.

FIG. 4 is a process explanatory diagram illustrating one step of the polishing method of the present invention.

FIG. 5 is a front view of a conventional polishing device.

FIGS. 6A and 6B are front views showing the epitaxial growth surface of a typical semiconductor wafer.

[Explanation of symbols]

1. Polishing equipment 2 Guide 3 Wafer parallelization device 4 Load 5 Polishing jig 6　　　　　Polishing plate 7 Semiconductor wafer 8 Heating plate 9 Epitaxial growth surface 10 Wax 11 Hot plate 12 Protrusion 13 Abrasive material 14 Non-epitaxial growth surface

Claims (2)

[Claims] 1. A method for polishing a semiconductor wafer in which one surface of the semiconductor wafer is polished by relatively moving a polishing plate and the semiconductor wafer, wherein wax is placed on the non-polished surface of the semiconductor wafer, and the wax is removed from the surface of the semiconductor wafer. A method for polishing a semiconductor wafer, the method comprising: applying a load to the semiconductor wafer through the semiconductor wafer. 2. The method of polishing a semiconductor wafer according to claim 1, wherein the wax is placed so as to cover projections formed on the non-polishing surface.