JPS63202034A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To prevent warping in a semiconductor substrate without a time for forming, by additionally manufacturing a semiconductor substrate having protruding and recess parts, which are complementary to recess and protruding parts of another semiconductor substrate, bonding both substrates through an insulating film and thereafter polishing the substrates. CONSTITUTION:An oxide film 2a is formed on a silicon substrate 1a. A patterned oxide film 2b is similarly formed on a silicon substrate 1b, which is separately prepared. The patterns of the oxide films 2a and 2b are complementary to each other. Oxide films 4a and 4b are formed on a high concentration impurity diffused layer 3 of the silicon substrate 1a and on the silicon substrate 1b, respectively. SOG 5 is further applied on the oxide film 4a on the silicon substrate 1a. The silicon substrates 1a and 1b are tightly contacted, and heat treatment is performed. Then the SOG 5 is chemically bonded to the oxide films 4a and 4b, and both films are bonded as a unitary body. After the separately manufactured two semiconductor substrates are bonded, polishing is performed. Thus the forming time of a conventional polysilicon layer is not required, and the warping problem of the semiconductor substrates is eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method of manufacturing a semiconductor device, and more particularly to a method of manufacturing a semiconductor device separated by an insulating layer.

[Prior Art] FIG. 2 is a cross-sectional view showing the manufacturing process of a conventional semiconductor device separated by an insulating layer.

Hereinafter, a conventional manufacturing method will be explained with reference to the drawings.

First, an oxide film 2 is formed on a silicon substrate 1 by a thermal oxidation method or a CVD method, and then patterned by photolithography or the like (see FIG. 2(a)).

The semiconductor substrate 1 is etched by wet or dry etching using the patterned oxide film 2 as a mask (see FIG. 2(b)).

After removing the oxide film 2, a high concentration impurity is injected into the entire surface of the silicon substrate 1 which has become uneven, and a high concentration impurity diffusion layer 3 is formed using a diffusion method or the like (see FIG. 2(c)). .

Next, a high concentration impurity diffusion layer 3 is continuously formed on the uneven portion.
An oxide film 4 serving as an insulating layer is formed thereon by the CVD method, and a polysilicon layer 7 having a thickness of about 1100 t1 is further formed thereon by the same CVD method (see FIG. 2(d)).

Finally, after inverting the substrate, polishing is performed from the back surface of the uneven portion of the silicon substrate 1 to the convex portion of the polysilicon layer 7, thereby manufacturing a semiconductor device with insulating layer separation in which a group of silicon substrates 1 are mutually independent. (See Figure 2(e)).

[Problems to be Solved by the Invention] In the conventional manufacturing method as described above, it takes an enormous amount of time to form a polysilicon layer to a thickness of several 100 μm using the CVD method, and it takes a long time to form the polysilicon layer. Since the semiconductor substrate warps due to the residual stress caused by the thermal effects of the process, there is a problem that the amount of polishing is not constant in the subsequent polishing process, and the insulating layer cannot be separated with high accuracy.

The present invention has been made to solve these problems, and provides a method for manufacturing a semiconductor device in which an insulating layer is separated, which does not require long-term formation of a polysilicon layer and does not cause warping of a semiconductor substrate. The purpose is to

[Means for Solving the Problems] In the manufacturing method according to the present invention, instead of forming a conventional polysilicon layer, a semiconductor substrate having an uneven portion complementary to the uneven portion of the semiconductor substrate is separately manufactured, and both are combined. After bonding via an insulating film, polishing is performed.

[Function] In this invention, a separately manufactured semiconductor substrate is used for the portion corresponding to the conventional polysilicon layer, so no time is required for its formation, and the time it is exposed to heat is drastically reduced, which prevents the semiconductor substrate from warping. I won't let you.

[Example] FIG. 1 is a sectional view showing a manufacturing process in an example of the present invention.

The manufacturing method of the present invention will be explained below with reference to the drawings.

First, as in the conventional example, an oxide film 2a is formed on a silicon substrate 1a by a thermal oxidation method or a CVD method, and this is patterned by photolithography. Similarly, a patterned oxide film 2b is also formed.

At this time, the patterning of the oxide films 2a and 2b is complementary to each other (see FIG. 1(a)). Using the patterned oxide films 2a and 2b as masks, the silicon substrates 1a and 1b are subjected to a wet or dry process, respectively. Etching is performed (see Fig. 1(b)).

After removing the oxide films 2a and 2b, the silicon substrate 1a
For the above case, a high concentration impurity is implanted into the entire uneven portion, and a high concentration impurity diffusion layer 3 is formed using a diffusion method or the like (
(See Figure 1(c)).

Next, oxide films 4a and 4b which will become insulating layers are formed by CVD or the like on the high concentration impurity diffusion layer 3 of the silicon substrate 1a and the silicon substrate 1b, respectively (see FIG. 1(d)). As for the silicon substrate 1a, 5OG5 is coated on the oxide film 4a to a thickness of several hundred to several thousand layers (see FIG. 1(e)).

Furthermore, the uneven portion of the silicon substrate 1a and the silicon substrate 1b
600~1.
When heat-treated at about ooo°C, 5OG5 is vitrified and chemically bonded with the oxide films 4a and 4b.
Both are integrally joined (see FIG. 1(f)).

Finally, invert the integrated substrate to form a silicon substrate 1a.
By polishing the silicon substrate 1b to the convex portion, a semiconductor device separated by an oxide film 6 serving as an insulating layer is completed (see FIG. 1(g)).

In the above embodiment, the uneven portions of the semiconductor substrate were formed by an etching method, but it goes without saying that other methods can produce similar effects.

Further, in the above embodiment, 5OG5 was applied to the silicon substrate la side, but the same effect can be obtained even if it is applied to the silicon substrate lb side or both sides.

Further, in the above embodiments, SOG is used during bonding, but other vitrified liquid materials may be used, and SOG
It may also contain impurities such as arsenic, phosphorus, boron, and antimony.

[Effects of the Invention] As explained above, this invention performs polishing after bonding two separately manufactured semiconductor substrates, which eliminates the huge amount of time required to form a polysilicon layer as in the conventional method. Since the problem of warping of the semiconductor substrate caused by this is also resolved, the present invention has the effect of providing a method for manufacturing semiconductor devices separated by an insulating layer with high precision and no variation in polishing amount.

Furthermore, since the time during which the polysilicon layer is exposed to heat effects during formation is shortened, re-diffusion of the impurity diffusion layer is also minimized, and a semiconductor device with good electrical characteristics can be manufactured.

[BRIEF DESCRIPTION OF THE DRAWINGS] Fig. 1 is a cross-sectional view of a process in an embodiment of the present invention;
The figure is a process sectional view of a conventional manufacturing method. In the figure, la and lb are silicon substrates, and 2a. 2b is an oxide film, 3 is a high concentration impurity diffusion layer, 4a+4b is an oxide film, 5 is SOG, and 6 is an oxide film. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (9)

[Claims] (1) Forming an uneven portion on the first main surface of a first semiconductor substrate having a first main surface and a second main surface; and forming an impurity diffusion layer on the uneven portion of the first semiconductor substrate. a step of forming an uneven portion complementary to the uneven portion of the first semiconductor substrate on the first main surface of a second semiconductor substrate having a first main surface and a second main surface; a step of bonding the uneven portion of the first semiconductor substrate and the uneven portion of the second semiconductor substrate via an insulating layer; A method for manufacturing a semiconductor device separated by an insulating layer, comprising the step of polishing until the bonded second semiconductor substrate is exposed. (2) The step of forming the uneven portion includes: forming a first film having a first pattern as a mask for etching on the first main surface of the first semiconductor substrate; 2. The method of manufacturing a semiconductor device according to claim 1, comprising the step of etching the first main surface using a first film as a mask. (3) The step of forming the uneven portion includes using a second pattern complementary to the first pattern as a mask for etching on the first main surface of the second semiconductor substrate. 3. The method of manufacturing a semiconductor device according to claim 2, comprising the steps of: forming a second film; and etching the first main surface using the second film as a mask. (4) The insulating layer is an oxide film formed on the uneven portion of the first semiconductor substrate and on the uneven portion of the second semiconductor substrate, A method for manufacturing a semiconductor device according to item 2 or 3. (5) The method of manufacturing a semiconductor device according to claim 4, wherein the first semiconductor substrate and the second semiconductor substrate are bonded by applying a vitrified liquid material. (6) The method for manufacturing a semiconductor device according to claim 5, wherein the vitrified liquid material is spin-on glass (SOG). (7) The method for manufacturing a semiconductor device according to claim 6, wherein the spin-on glass contains impurities. (8) The method for manufacturing a semiconductor device according to claim 7, wherein the impurity is selected from a group of elements consisting of arsenic, phosphorus, boron, and antimony. (9) The method for manufacturing a semiconductor device according to claim 6, 7, or 8, wherein the spin-on glass and the oxide film are chemically bonded by heat treatment.