JPH0218948A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To enable control of a thin film so as to improve the performance of a device by opening an hole at one side of a semiconductor substrate for element formation, and measuring the depth of the hole in a filming process. CONSTITUTION:A hole is opened at one side of a semiconductor substrate 1 for element formation, and the semiconductor substrate 1 for element formation is bonded to a semiconductor substrate for supporting through an insulating layer. And the depth of the hole is measured in a filming process. Accordingly, when forming the substrate, the dispersion of film thickness by undulation, etc., is suppressed, and the film thickness and distribution of an element formation layer during etching polishing can be measured. Hereby, the control of the thickness of a thin film of the element formation layer is made possible, and performance improvement of a device becomes possible.

Description

[Detailed description of the invention] [Summary] 5OI (Silicon on In5) by adhesion method
(ulator) substrate manufacturing method.

Enables measurement of the thickness and distribution of the element formation layer.

The purpose is to improve device performance by making it possible to control thin film thickness.

A step of making a hole opening on at least one side in a semiconductor substrate for forming an element, bonding the semiconductor substrate for forming an element to a supporting semiconductor substrate via an insulating layer, and a step of thinning the semiconductor substrate for forming an element, The structure includes a step of measuring the depth of the hole in the step of thinning the film.

[Industrial application field]

The present invention relates to a method of manufacturing a semiconductor device, and particularly to a method of manufacturing a So1 substrate using an adhesive method.

In recent years, advances in silicon (St) IC technology have increased the demand for higher speed and lower power consumption devices.

There are limits to how far conventional technology can respond to this, such as simply miniaturization and optimization of power supply voltage.

An approach has been to change the bulk materials used.

Therefore, SOI substrates are used to dramatically improve device performance, especially high speed, of devices such as CMO3 ICs and 3D ICs by using the highly accumulated St IC technology as is.

One of the economical methods for forming it is to
There is a method of bonding two Si substrates together.

[Conventional technology]

The method for forming an SO1 substrate by bonding two Si substrates via an insulating layer is as follows.

First, a thin Si substrate, which will become the element formation layer, is oxidized to form silicon dioxide (Si(h)Jl) on the surface, which is then pressure-bonded to a thick Si substrate, which will become the supporting substrate, and then heat treated at about 800°C to bond it. do.

Next, the thin Si substrate is etched and polished to a desired thickness to form an element forming layer.

This etching polishing is the key to determining the quality of the Sol substrate.

In the conventional method, in order to obtain uniformity in the thickness of the two films, it is necessary to perform etching polishing with high precision, and for this purpose, etching polishing has to be interrupted midway through and the film thickness has to be monitored many times.

[Problem to be solved by the invention] As mentioned above, in the conventional method, when etching and polishing a thin Si substrate to form an element formation layer, it is difficult to determine how thick the element formation layer becomes during etching polishing. I couldn't recognize Taka. Therefore, the film thickness distribution, which affects device characteristics, could not be measured.

In particular, in order to improve the degree of device integration, it is necessary to fabricate thin element formation layers with good controllability.

In order to manufacture a high-performance CMOS IC, the thickness of the element formation layer must be 1 μm or less, but the thin substrate used cannot be made 30 μm or less.

A considerable amount of etching and polishing is required.

For this reason, during etching polishing, there was a problem in that the substrate was undulated and the film became thinner at one periphery and thicker at the center, resulting in non-uniform film thickness.

The present invention suppresses variations in film thickness due to waviness and the like when forming a So1 substrate using an adhesion method, makes it possible to measure the film thickness and distribution of the element forming layer during etching polishing, and enables control of thin film thickness. The purpose is to improve device performance.

Means for Solving Problem C] The solution to the above problem is a step of making a hole opening on at least one side in a semiconductor substrate for forming an element, and bonding the semiconductor substrate for forming an element to a supporting semiconductor substrate via an insulating layer. This is achieved by a method for manufacturing a semiconductor device comprising the steps of thinning the semiconductor substrate for forming an element, and measuring the depth of the hole in the thinning step.

[Effect]

In the present invention, a plurality of holes of a predetermined depth are made on the adhesive side or the polished side of a substrate for forming an element, or a plurality of through holes are made on both sides, and then this substrate is oxidized to form a thick support. When bonding to a substrate and then etching and polishing the element forming substrate, the film thickness can be determined by measuring the depth of the hole or through hole.

If a hole is made to a predetermined depth on the adhesive side, the hole will be exposed when a predetermined film thickness is reached, and the film thickness can be monitored by measuring the depth of the hole. In this case, even with one through hole, monitoring during etching and polishing is possible, but an alarm indicating that the hole is exposed when the desired thickness is approached cannot be obtained.

By drilling a large number of deep holes (with enough depth to leave the desired thickness of bone) on the polishing surface side, uniform polishing can be achieved by measuring the depth of these holes during etching polishing. It can be determined whether the Furthermore, since there are many holes on the two surfaces, the polishing speed is high until the depth of the holes is reached, the polishing load is reduced, and uneven film thickness distribution such as waviness can be improved. As the polishing progresses and the holes disappear, the polishing speed decreases, making it easier to control the film thickness.

〔Example〕

(1) Example of forming holes on the adhesive surface of the element forming substrate: 1st
FIGS. (1) to (3) are cross-sectional views illustrating a method for forming an SOI structure according to an embodiment of the present invention.

In FIG. 1(1), a Si substrate 1 with a thickness of about 30 μm is used as a semiconductor substrate for forming elements.

A plurality of holes with a predetermined depth 9, for example 5 μm, are made in the Si substrate 1.

The size of the hole is arbitrary, but it should be 1 m to allow visual inspection.
Make it about W@square.

Holes in Si are formed using a resist mask or by active ion etching (RIE).

For Si RIE, 5iC14 is used as the etching gas, and the pressure is reduced to 10-” Torr and the frequency is 13.
．． This is performed by applying 56 MHz power of 400 W.

In FIG. 1(2), a Si substrate 1 is thermally oxidized to form a 1000-layer Si layer IA on its surface.

A thick Si substrate 2 having a 5000-thick 5iOz layer 2A formed on one surface is prepared as a supporting substrate.

Place the holed side of the Si substrate 1 on the support substrate 5i02 layer 2^
Place it on top and glue it.

Adhesion is performed by applying a direct current voltage of about IOOV and heat treatment at 450° C. for about 60 minutes in nitrogen.

In FIG. 1(3), the Si substrate 1 is etched and polished until holes appear on the surface.

For etching polishing, for example, a method called mechanochemical is used.

This method is a polishing method normally used for polishing during wafer manufacturing, and has the characteristic that the polished surface becomes a mirror surface upon completion of polishing.

With the above steps, the adhesive Sol substrate is completed. By measuring the depth of the holes on the substrate surface, the thickness of the element forming layer 1 and its distribution can be determined. This measured value can be used as a monitor during etching.

Moreover, even if a through hole is made in the element forming substrate as described above,
Film thickness can be monitored during etching and polishing.

(2) Example of forming holes on the polished surface of the element forming substrate: 2nd
Figures (11 to 3) are cross-sectional views illustrating a method for forming a Sol structure according to another embodiment of the present invention.

In FIG. 2 (11), a Si substrate 1 with a thickness of about 30 μm is used as a semiconductor substrate for forming an element.

A large number of deep holes are drilled in the Si substrate 1 at a depth that leaves a desired thickness of bone with plenty of room. For example, a large number of holes with a depth of about 20 μm are made.

The size of the hole is arbitrary, but in this case it is better to make it larger than the example shown in FIG. 1 in order to reduce the initial polishing load.

In FIG. 2(2), the Si group vi1 is thermally oxidized to form a 5i02 layer IA on its surface.

A thick Si substrate 2 with a SiO□ layer formed on one surface is prepared as a supporting substrate.

Place the non-hole side of the Si substrate 1 on the support substrate SiO□
Place and adhere on layer 2A.

In FIG. 2(3), etching and polishing of the Si substrate 1 is performed until holes disappear from the surface.

Subsequently, etching and polishing of the Si substrate 1 is continued to finish the film to a predetermined thickness to form an element forming layer.

According to this example, the variation in film thickness due to waviness, which has been a problem with conventional bonded substrates, can be suppressed, and the thin film thickness of So1
Substrates can be manufactured reproducibly.

〔Effect of the invention〕

As explained above, according to the present invention, S
When forming an O1 substrate, variations in film thickness due to waviness or the like can be suppressed, and the film thickness and distribution of the element forming layer during etching and polishing can be measured.

Therefore, it becomes possible to control the thin film thickness of the element forming layer and improve the performance of the device.

[Brief explanation of the drawing]

Figures 1 (1) to (3) show Sol according to an embodiment of the present invention.
FIG. 3 is a cross-sectional view illustrating a method of forming a structure. FIG. 2 (11-(3)) shows an SO according to another embodiment of the present invention.
FIG. 3 is a cross-sectional view illustrating a method of forming an I structure. In fig. 1 is a semiconductor substrate for element formation, which is a thin Si substrate. LA is a SiO□ layer. 2 is a support substrate, and the thick St substrate 2A is the name of the screen diagram of the SiO2 layer implementation item J. 1 Flash

Claims (1)

[Claims] A step of making a hole in at least one side of a semiconductor substrate for forming an element and bonding the semiconductor substrate for forming an element to a supporting semiconductor substrate via an insulating layer; A method for manufacturing a semiconductor device, comprising the steps of: thinning the film; and measuring the depth of the hole in the thinning step.