JPH01230255A - Manufacture of semiconductor substrate - Google Patents

Abstract

PURPOSE:To make bubbles hard to remain in bonding surfaces and to reduce stress, by using a semiconductor layer in a fused state to bond two semiconductor substrates. CONSTITUTION:Two sheets of Si substrates 11 and 12 are prepared. The substrates 11 and 12 have SiO2/Si structures having SiO2 layers on the surfaces. A polycrystalline Si layer 15 having a thickness of about 10-50Angstrom are formed on the layer 13 of the substrate 11. Then, the sides of the layers 13 and 14 are made to face each other, and the substrates 11 and 12 are brought into contact together. The layers 13 and 14 are selectively heated. Since the layer 15 is very thin, only the layer 15 is fused when the layers 13 and 14 are selectively heated. Thereafter the heating is stopped. Then, the layer 15 is solidified, and the substrates 11 and 12 are bonded together. Since the layer 15 is fused, remaining bubbles in the bonding surfaces of the substrates 11 and 12 are very few, and stress is also less.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method of manufacturing a semiconductor substrate having a WA edge layer therein.

[Summary of the invention]

The present invention provides a method for manufacturing a semiconductor substrate as described above.
By bonding first and second semiconductor substrates having insulating layers on their respective surfaces using a molten semiconductor layer,
This makes it possible to manufacture high quality semiconductor substrates.

[Conventional technology]

It is well known that SOI substrates not only have great advantages when producing LSIs, but also have excellent electrical properties.

At present, a bonded substrate is considered to be a promising material for realizing such an SOI substrate due to its good crystallinity.

That is, JP-A-60-121776 and ^ppl.

Phys-Lett, +Vo1.4B+N11+6 J
5iO of two substrates with Sing/Si structure, as described in 1986 PP78-80 etc.
If one side is brought into contact with another and thermocompression bonding or electrostatic bonding is performed, two
The two substrates become one complete substrate.

[Problem to be solved by the invention]

However, with this method, it is not possible to prevent fine air bubbles from remaining on the adhesive surface, and the stress is relatively large.

Therefore, the quality of the Sol substrate manufactured by such a method is not necessarily high.

[Means to solve the problem]

The method for manufacturing a semiconductor substrate according to the present invention includes first and second semiconductor substrates 11 having insulating layers 13 and 14 on their respective surfaces.
．． 12, a step of making the insulating layers 13 and 14 face each other via the molten semiconductor layer 15, and solidifying the molten semiconductor N15 to form the first and second semiconductor substrates 11. 12 to each other.

(Function) In the method for manufacturing a semiconductor substrate according to the present invention, the semiconductor layer 15 in a molten state is used to form the first and second semiconductor substrates 11.1.
Since the two are bonded together, air bubbles are unlikely to remain on the bonded surface and stress is also low.

〔Example〕

Hereinafter, first and second embodiments of the present invention will be described with reference to FIG.

In the first embodiment, two Si substrates 1 as shown in FIG. 1A are used.
1. Prepare 12 first. These Si substrates 11.12
is 5iOt/S with SiO□N13.14 on the surface
Further, on the Si layer 13 of the Si substrate 11, a polycrystalline Si layer 15 of about 10 to 50 layers of thermal acid is formed.

Next, as shown in FIG. 1B, the Si substrates 11 and 12 are brought into contact with each other with the 5L (h layers 13 and 14 sides facing each other), and the 5int layer 1 is
3.Selectively heat 14.

By the way, since the polycrystalline Si layer 15 is very thin as described above, the grain size is small even when grown by CVD, and the heat dissipation rate is also low. Also, Si has a lower melting point than Sing. For these reasons, when the SiO□ layer 13.14 is selectively heated, only the polycrystalline Si layer 15 sandwiched between the sto and Jl 13.14 is melted.

Thereafter, when the heating is stopped, the polycrystalline Si layer 15 is solidified and the Si substrates 11 and 12 are bonded to each other.

Therefore, by grinding the Si substrate 12 from this state to form a thin Si layer, an SOI substrate as shown in FIG. 1B can be obtained.

In the first embodiment, the polycrystalline Si layer 15 originally has a flat surface because of its small grain size.
Since the i-layer 15 is melted, there are very few bubbles remaining on the bonding surfaces of the Si substrates 11 and 12 after solidification of the polycrystalline Si layer 15, and there is also little stress.

Furthermore, since the polycrystalline Si layer 15 is very thin, the potential is transmitted to adjacent elements, and the presence of the polycrystalline Si layer 15 can be virtually ignored. Note that in order to further reduce the transmission of potential to adjacent elements, it is sufficient to make the Sin layer 14 thicker than the sto, m 13.

Next, a second embodiment will be explained. This second embodiment is based on the first
Amorphous s instead of polycrystalline 5ijii15 in the example
tJ! This embodiment has substantially the same steps as the first embodiment except that i is used.

The amorphous isi layer is formed by plasma CVD that decomposes SiH*.
LP-C that decomposes SiH* at temperatures below 580℃
It can be formed by a method in which a polycrystalline Si layer is grown by VD or LP-CVD and then made amorphous by ion implantation, or by a vapor deposition method in which amorphous Si is vapor-deposited.

Amorphous Si melts when heat is rapidly applied, even if the amount of energy itself is small, that is, at a low melting point.

Therefore, it is convenient for bonding the Si substrates 11 and 12 together.

〔Effect of the invention〕

In the method for manufacturing a semiconductor substrate according to the present invention, the first and second
Since air bubbles are less likely to remain on the bonding surfaces of the semiconductor substrates and there is less stress, high quality semiconductor substrates can be manufactured.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view sequentially showing the steps of a first embodiment of the present invention. In addition, in the symbols used in the drawings, 11.12・------・---5i substrates 13, 14
−−−−−−−−−−5 io t J! 115-・
...-----------Polycrystalline St layer.

Claims (1)

[Claims] A method for manufacturing a semiconductor substrate having an insulating layer therein, comprising the steps of: preparing first and second semiconductor substrates having insulating layers on their respective surfaces; a step of making the insulating layers face each other; and solidifying the molten semiconductor layer to form the first and second semiconductor layers.
A method for manufacturing a semiconductor substrate, comprising the steps of: adhering semiconductor substrates to each other.