JPH0521590A - Manufacture of dielectric isolation substrate - Google Patents

Abstract

PURPOSE:To obtain a dielectric isolation substrate wherein warp is small and a region available for element formation is wide, by forming a semiconductor island type region and retainer by using the same property material. CONSTITUTION:A semiconductor single crystal plate 6 for a retainer is stuck on a trentch forming surface of a semiconductor single crystal plate 2 for element formation wherein trenches 3 for isolation are formed on the surface and the trench forming surface is covered with an insulating film 4. The surface of the semiconductor single crystal plate 2 for element formation opposite to the trench forming surface is polished until the bottoms of the trenches for isolation are exposed. Thereby a plurality of semiconductor single crystal regions for element formation subjected mutually electrically to dielectric isolation are made to appear.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a dielectric (insulating layer) separation substrate.

[0002]

2. Description of the Related Art A dielectric isolation substrate for producing a semiconductor device (hereinafter referred to as "DI substrate" as appropriate) is a semiconductor single crystal region for element formation (hereinafter referred to as "semiconductor island-like" as appropriate) electrically isolated from each other. A plurality of "regions" are provided on the support. Conventionally, there has been a problem that the dielectric isolation substrate has a large warp. This is because the support is polysilicon (polycrystalline silicon), whereas the semiconductor island-shaped region is single crystal, and the material used is one of which is polycrystalline and the other of which is significantly different in property from single crystal. Because there was.

Therefore, a method for obtaining a dielectric isolation substrate with less warpage has been proposed as follows. First, as shown in FIG. 8, two semiconductor single crystal plates 81 and 82 are bonded together with an oxide film 83 for an insulating film interposed therebetween. One semiconductor single crystal plate 81 is for element formation, and the other semiconductor single crystal plate 82 is for a support. Then, as shown in FIG. 9, the surface of the semiconductor single crystal plate 81 for element formation is polished and thinned, and then an oxide film is formed on the remaining portion of the semiconductor single crystal plate 81 for element formation as shown in FIG. Separation V reaching 83
The groove 84 is formed by anisotropic etching.

After that, as shown in FIG. 11, the V-groove forming surface is covered with an oxide film 85 for an insulating film, and then, as shown in FIG. Then, as shown in FIG. 13, the DI substrate 80 can be obtained by polishing from the V groove forming surface side to expose the surface of the element forming semiconductor island region 81a. This DI board 80
Has a small warp because the element-forming semiconductor island region 81a is supported by a semiconductor single crystal support having the same properties.

[0005]

However, although the dielectric isolation substrate 80 has a small warp, it has a drawback that the element formation area is also small. The surface area (the area of the exposed surface) of the semiconductor island-shaped region 81a for element formation is small. Since each semiconductor island region 81a has a shape with a wide bottom and a narrow surface, the surface area that determines the element formable region becomes small, which is not practical.

In view of the above circumstances, it is an object of the present invention to provide a method capable of obtaining a dielectric isolation substrate having a small warp and a wide element formation area.

[0007]

In order to solve the above-mentioned problems, in the method of manufacturing a dielectric isolation substrate of the present invention, an isolation semiconductor is formed on the surface thereof, and the isolation surface is covered with an insulating film. A semiconductor single crystal plate for a support is bonded on the groove forming surface of the single crystal plate, and a surface opposite to the groove forming surface of the element forming semiconductor single crystal plate is a bottom of the separation groove. By polishing until it is exposed, a plurality of element-forming semiconductor single crystal regions electrically isolated from each other are exposed on the support.

According to the present invention, as described in claim 2,
After filling the groove of the semiconductor single crystal plate for support with the landfill material, the semiconductor single crystal plate for support is bonded. Usually, the filling marks of the landfill material are polished to be flat, and then the semiconductor single crystal plate for a support is bonded. Further, when a semiconductor single crystal plate for a support is bonded, an oxide film may or may not be interposed on the bonding surface. If the latter oxide film is not interposed, there is an advantage that the number of steps can be reduced.

The semiconductor single crystal plate for element formation and the support in the present invention is, for example, a silicon single crystal plate, and the landfill material is, for example, polysilicon, but it is not limited to these. Yes.

[0010]

The DI substrate obtained by the present invention has a small warp because both the semiconductor island region and the support are made of the same material as the semiconductor single crystal. The DI substrate obtained by the present invention has a shape in which each semiconductor island region is wider on the surface side and narrower toward the bottom, which is the reverse of the conventional shape. Therefore, the surface area that determines the element formable region is large. The device feasible range has expanded. This is because in the method of the present invention, the DI substrate is manufactured so that the surface opposite to the groove forming surface (the surface having the groove opening) (the cross section where the groove bottom is located) becomes the surface of the semiconductor island region. is there.

That is, the separation groove is narrowed from the surface toward the bottom, and the element is formed between the groove forming surface (the surface having the groove opening) and the opposite surface (the cross section where the groove bottom is located). Comparing the area occupied by the semiconductor single crystal as the formable region, the latter is wider. Therefore, in the case of polishing so that the surface opposite to the groove forming surface of the latter becomes the surface of the semiconductor island region, in the conventional case where the latter groove forming surface becomes the surface of the semiconductor island region As compared with the above, the semiconductor single crystal region which is the element formable region is wider, and as a result, the element formable region is expanded.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The manner in which a dielectric isolation substrate is manufactured according to an embodiment of the present invention will be described in detail below with reference to the drawings. Of course, the present invention is not limited to the following embodiments. -Example 1-In Example 1, a DI substrate was obtained as follows.

First, the semiconductor single crystal plate 2 for element formation shown in FIG. 2, that is, the single crystal plate 2 in which the V groove 3 for isolation is formed on the surface and the groove forming surface is covered with the insulating layer 4 is described below. To prepare. First, as shown in FIG. 1, the isolation V groove 3 is formed on one surface of the semiconductor single crystal plate 2 by anisotropic etching, and then the V groove formation surface of the semiconductor single crystal plate 2 is used as an insulating film. It is covered with an oxide film (eg, SiO ₂ film) 4.

Next, as shown in FIG. 3, polysilicon (filling material 5) is deposited to fill the V-grooves 3 and then the fill marks are polished to be flat. Then, a semiconductor single crystal plate for a support is bonded onto it. That is, as shown in FIG.
The semiconductor single crystal plate 6 for a support is bonded via an oxide film (eg, SiO ₂ film) 7. An oxide film is previously formed on both or one of the surface of the landfill material and the surface of the semiconductor single crystal plate for support, which is on the bonding side, and is then bonded.

Finally, as shown in FIG. 5, the back surface of the semiconductor single crystal plate 2 for element formation (the surface opposite to the separation groove formation surface).
If polishing is performed from the side until the bottom of the separation V groove 3 is exposed,
I substrate 1 is obtained. In the obtained DI substrate 1, a plurality of semiconductor island-like regions 1a electrically isolated from each other are exposed on the support. Each semiconductor island region 1a has a shape in which the surface side is larger than the bottom side, and the element formable region is wide. Needless to say, the semiconductor island region 1a and the support are made of the same semiconductor single crystal, and warp is small.

Example 2 In Example 2, as in Example 1, as shown in FIGS. 1 to 3, after filling the V groove 3 of the semiconductor single crystal plate 2 for element formation with the landfill material 5, The filling marks are ground and flattened, and then, unlike in the first embodiment, as shown in FIG. 6, the semiconductor single crystal plate 6 for the support is directly attached to the filling material 5 without an oxide film. Pasted on.

Subsequently, as shown in FIG. 7, the back surface of the semiconductor single crystal plate 2 for element formation (the surface opposite to the separation groove formation surface).
If polishing is performed from the side until the bottom of the separation V groove 3 is exposed,
I substrate 1 is obtained. In the obtained DI substrate 1, again, the semiconductor island regions 1a electrically isolated from each other are formed.
... A plurality of them appear on the support. Each semiconductor island region 1a has a shape in which the surface side is larger than the bottom side, and the element formable region is wide.

Comparing the case of Example 2 with the case of Example 1, an oxide film is not formed between the semiconductor single crystal plate 2 for forming the element and the semiconductor single crystal plate 6 for the support, and thus the oxide film is formed. There is an advantage that the number of steps is reduced by the amount of steps not required.

[0019]

As described above, the DI substrate obtained according to the present invention has a small warp because the semiconductor island region and the support are made of the same material, and each semiconductor island region has a small warp. Since the surface area of the region is large, the element feasible region is widened, which is very practical.

[Brief description of drawings]

FIG. 1 is a cross-sectional view for explaining a separation groove forming process in a first embodiment.

FIG. 2 is a cross-sectional view for explaining an oxide film forming step for covering a groove forming surface in the first embodiment.

FIG. 3 is a cross-sectional view for explaining a separation groove burying process in the first embodiment.

FIG. 4 is a cross-sectional view for explaining a step of laminating a semiconductor single crystal plate for a support in Example 1.

5 is a cross-sectional view showing the DI substrate obtained in Example 1. FIG.

FIG. 6 is a cross-sectional view for explaining a semiconductor single crystal plate bonding step for a support in Example 2.

FIG. 7 is a cross-sectional view showing a DI substrate obtained in Example 2.

FIG. 8 is a cross-sectional view for explaining a semiconductor single crystal plate bonding step in a conventional method.

FIG. 9 is a cross-sectional view for explaining a surface polishing process of a semiconductor single crystal plate by a conventional method.

FIG. 10 is a cross-sectional view for explaining a separation groove forming step in a conventional method.

FIG. 11 is a cross-sectional view for explaining an oxide film forming step for covering a separation groove forming surface by a conventional method.

FIG. 12 is a cross-sectional view for explaining a separation groove burying step in a conventional method.

FIG. 13 is a cross-sectional view showing a DI substrate obtained by a conventional method.

[Explanation of sign]

1 Dielectric isolation substrate 1a Semiconductor single crystal region for element formation (semiconductor island region) 2 Semiconductor single crystal plate for element formation 3 V groove for separation 4 Oxide film for insulating film 5 groove landfill 6 Semiconductor single crystal plate for support 7 Oxide film

Claims (2)

[Claims] 1. A semiconductor single crystal plate for a support is bonded onto the groove forming surface of an element forming semiconductor single crystal plate having a separation groove formed on the surface and a groove forming surface covered with an insulating film. A plurality of electrically isolated layers are formed on the support by polishing a surface of the element-forming semiconductor single crystal plate opposite to the groove forming surface until the bottom of the separating groove is exposed. A method for manufacturing a dielectric isolation substrate, wherein a semiconductor single crystal region for element formation is exposed. 2. The method for manufacturing a dielectric isolation substrate according to claim 1, wherein the groove of the semiconductor single crystal plate for a support is filled with a filling material, and then the semiconductor single crystal plate for a support is bonded.