JPH04132256A - Manufacturing method of semiconductor laminated substrate - Google Patents

Abstract

PURPOSE:To make it possible to sufficiently bond the main surface of laminated semiconductor substrates to one another and to control a second semiconductor substrate that becomes an active domain to have a constant thickness by preparing sunken sections on the main surface of the second semiconductor substrate corresponding to the protrusions that are present on the main surface of a first semiconductor substrate. CONSTITUTION:SiO2 film 2 is prepared on the main surface of silicon substrate 1, followed by selectively etching the SiO2 film 2 taking a photoresist pattern as mask to prepare a plurality of protrudent sections 6 relative to the SiO2 film 2. On the other hand, the main surface of a second silicon substrate 3 is selectively etched to prepare sunken sections 7 thereon. Here, positions of sunken sections 7 are corresponding to positions of protrudent sections 6 prepare on the SiO2 film 2. The main surface of a first silicon substrate 1 and the main surface of the second silicon substrate 3 are put together and heated to bond them together, further followed by grinding the back surface of the second silicon substrate 3 until the protrudent sections 6 of Silicon O2 film 2 are partly exposed to prepare silicon film 3 as an active domain on the SiO2 film 2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a semiconductor multilayer substrate, and is particularly suitable for application to a method for manufacturing a Sol substrate using a bonding method.

[Conventional technology] SOT (Silicon O) using the bonding method
Conventionally, a method for manufacturing a substrate (In5lator) has been carried out as follows.

First, as shown in FIG. 2(a), a Sing film 2 is formed on the main surface of a first silicon substrate l by thermal oxidation.

Next, as shown in FIG. 2(b), the main surface of the second silicon substrate 3 is bonded to the main surface of the first silicon substrate 1, and the silicon substrates are bonded to each other by heat treatment.

Next, as shown in FIG. 2(C), the second silicon substrate 3 is polished from the back side, leaving a thin silicon film 3 as an active region on the Sing film 2, and forming an SO summer substrate. Form.

However, with this method, it is difficult to monitor the amount of polishing in the final polishing step, and therefore it is difficult to accurately control the thickness of the silicon film 3 to remain.

In order to solve this problem, the following methods have been taken.

First, as shown in FIG. 3(a), SiO□Ml! is applied to the entire main surface of the first silicon substrate 1 by thermal oxidation. form 2. On the other hand, a part of the main surface of the second silicon substrate 3 is thermally oxidized to locally form SiO□4.

The surface of this Sto, 4 protrudes convexly from the surface of the main surface of the silicon substrate 3, and the interface between SiO□4 and the silicon substrate 3 is deeper than the surface of the main surface of the silicon substrate vi3. It's there.

Next, as shown in FIG. 3(b), the main surfaces of the first silicon substrate 1 and the second silicon substrate 3 are bonded to each other and bonded by heat treatment.

Next, as shown in FIG. 3(C), the second silicon substrate 3 is polished from the back side. At this time, since the polishing rate of SiO2 is much lower than that of silicon, the 5iOz4 formed on the silicon substrate 3 acts as a stopper, and the S
Silicon film 3 left on the iO□ film 2 as an active region
The film thickness can be kept constant.

[Problem to be solved by the invention]

However, in the method shown in FIG. 3, since there are protrusions of SiO□4 on the main surface of the second silicon substrate 3,
As shown in FIG. 3(b), when the substrates are bonded together, voids may occur around the protrusions, resulting in poor adhesion, or the main surface of the silicon substrate 3 around the protrusions may not be able to maintain a flat surface. There were problems such as deterioration of silicon crystallinity due to bending.

The present invention has been made in view of the above-mentioned problems, and includes:
The present invention aims to provide a method in which the thickness of a silicon film serving as an active region can be controlled to be constant, and an SOI substrate can be manufactured without impairing crystallinity or adhesiveness.

[Means to solve the problem]

In order to solve the above problems, the method for manufacturing a semiconductor multilayer substrate of the present invention includes a step of forming an oxide film on the main surface of a first semiconductor substrate, and removing a part of the oxide film. a step of forming a convex portion relative to the film; a step of forming a concave portion on the main surface of the second semiconductor substrate at a position corresponding to the convex portion of the first semiconductor substrate; bonding the main surfaces of the first and second semiconductor substrates to each other so that the convex portions of the substrates fit into the concave portions of the second semiconductor substrate, and bonding them to each other by heat treatment; exposing the oxide film; and polishing the second semiconductor substrate from the back surface side thereof.

[Effect]

In the present invention, since the recess is formed at the position of the main surface of the second semiconductor substrate corresponding to the protrusion existing on the main surface of the first semiconductor substrate, the first and second semiconductor substrates are separated from each other. When bonded together, their respective principal planes are in close contact with each other. Therefore, no voids are formed in the vicinity of the protrusions, and no deflection of the main surface of the second silicon substrate occurs.

Since the protrusions of the oxide film provided on the soil surface of the first semiconductor substrate act as a stopper when polishing the second semiconductor substrate, the film thickness of the second semiconductor substrate that remains as the active region can be controlled at a constant level. can do.

〔Example] Embodiments of the present invention will be described below with reference to FIG.

First, as shown in FIG. 1(a), a 2.5 μm thick SiO□ film 2 is formed on the main surface of a silicon substrate 1 by thermal oxidation.

Next, 7 photoresist patterns were formed on the SiO□ film 2, and using this as a mask, the SiO□ film 2 was selectively etched to a depth of 5000 nm in a buffered hydrofluoric acid solution, and then the photoresist was removed. As shown in FIG. 1(b), a plurality of protrusions 6 are formed relative to the SiO□ film 2. Then, as shown in FIG.

On the other hand, a photoresist pattern is formed on the main surface of the second silicon substrate 3, and using this as a mask, the silicon substrate 3 is
The surface of the silicon substrate 3 is selectively etched to a depth of 5000 mm by plasma etching, and then the photoresist is removed to form a recess 7 on the surface of the silicon substrate 3, as shown in FIG. 1(C). Here, the position of the recess 7 formed on the surface of the silicon substrate 3 is determined when the main surfaces of the first and second silicon substrates 1 and 3 are bonded together. This corresponds to the position of the convex portion 6 formed in .

Next, as shown in FIG. 1(d), the main surfaces of the first silicon substrate 1 and the second silicon substrate 3 are bonded together, and heat treatment is performed to bond them together. At this time,
Since the convex portion 6 of the Sing film 2 formed on the first silicon substrate 1 fits within the concave portion 7 formed on the second silicon substrate 3, the flat surface excluding the convex portion 6 of the first silicon substrate l The planar parts of the second silicon substrate 3 and the second silicon substrate 3, excluding the recessed part 7, are in close contact with each other sufficiently. Further, the second silicon substrate 3 is not bent, and therefore its crystallinity is not impaired.

Next, as shown in FIG. 1(e), the second silicon substrate 3 is polished from the back side until a portion of the convex portion 6 of the SiO□ film 2 is exposed, thereby forming a Si layer.

A silicon film 3 with a thickness of approximately 5000λ is formed as an active region on the film 2.
is formed.

〔Effect of the invention〕

As explained above, according to the present invention, when manufacturing a semiconductor multilayer substrate by a bonding method, an oxide film formed on a first semiconductor substrate and a second semiconductor bonded thereon are bonded together. It has high adhesion to the substrate, and does not impair the crystallinity of the second semiconductor substrate as an active region.

[Brief explanation of drawings]

1(a) to 1(e) are cross-sectional views showing the manufacturing method of a semiconductor multilayer substrate according to an embodiment of the present invention in the order of steps, and FIG. 2(a)
) to (C) are cross-sectional views showing a conventional method for manufacturing a semiconductor multilayer substrate in order of steps, and FIGS. 3(a) to (c) are cross-sectional views showing another conventional method for manufacturing a semiconductor multilayer substrate in order of steps. . In addition, in the reference numerals used in the drawings, l...--First silicon substrate 2.
・・・・・・・・・ 3 ・・・・・・・・・ 6 ・・・・・・・・・ 7 ・・・・・・・・・Sin, film second silicon substrate convex part concave part

Claims (1)

[Claims] A step of forming an oxide film on the main surface of a first semiconductor substrate; a step of forming a relatively convex portion in the oxide film by removing a portion of the oxide film; forming a recess on a main surface of a second semiconductor substrate at a position corresponding to the projection of the first semiconductor substrate; and the projection of the first semiconductor substrate is formed in the recess of the second semiconductor substrate. A step of bonding the main surfaces of the first and second semiconductor substrates to each other so that they fit together and bonding them to each other by heat treatment, and polishing the second semiconductor substrate from the back side until the oxide film is exposed. A method for manufacturing a semiconductor multilayer substrate, comprising the steps of: