JPH0563169A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To manufacture a semiconductor device, particularly, an SOI substrate consisting of a direct couple of silicon wafers. CONSTITUTION:A method of manufacturing an SOI substrate consisting of a direct couple of silicon wafers 1 where after a substrate 4 is coupled with a wafer 5 both-faced with mirror faces, the wafer of the substrate 4 is coated with a resist 3 and etched on the front down into a constant thickness, and the resist 3 is removed to manufacture an SOI substrate.

Description

Detailed Description of the Invention

[0001]

[Object of the Invention]

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device, and more particularly to a method for manufacturing an SOI substrate which is formed by directly bonding both silicon wafers.

[0003]

2. Description of the Related Art An SOI (Silconon Lnsulator) substrate having a characteristic of low leakage current and low parasitic capacitance is manufactured by the method shown in FIGS.
That is, the wafer 9 serving as the substrate of the SOI substrate
And the wafer 10 whose front and back surfaces are mirror surfaces,
₂ O ₂ + H ₂ SO ₄ was washed and hydrophilized, and the fact that the hydroxyl group (—OH) was hydrogen bonded was used to bond 1
The bonding is completed by treating for 2 hours at 100 ° C. in N ₂ , which is shown in (b).

Next, a portion of the silicon 11 on one side of the SOI substrate thus obtained is scraped off by rough polishing called lapping. This is shown in (c). The portion of the silicon 12 is removed by an etching liquid in order to remove the mechanical strain of the rough polishing, which is shown in (d).

Next, polishing for final polishing is performed so that the film thickness of the silicon oxide is uniform and the surface is flat, and the portion of the silicon 13 is scraped off to obtain S as shown in (e).
The OI substrate is manufactured. (Document “Trial manufacture of MOSFET on SOI substrate by direct bonding” Institute of Electronics, Information and Communication Technology, Research Report Vol.87 No 344 P43-
48)

[0006]

However, in the method of manufacturing the SOI substrate, the polishing process is quite complicated, and the final polishing is different from the normal mirror polishing method for bulk silicon.

This is because the film thickness distribution is measured by polishing so as to leave a thin film of silicon, the processing amount is adjusted, and the film thickness is adjusted before finishing polishing in order to reduce film thickness variation between wafers. It is necessary to measure the wafers and sort the wafers according to the thickness to perform polishing, which complicates the process and is not suitable for large-scale processing.

An object of the present invention is to provide a method of manufacturing an SOI substrate in which the flatness of the wafer is ensured even after the bonding in the manufacture of the SOI substrate and the processing steps are simplified.

[0009]

[Constitution of the invention]

[0010]

[Means for Solving the Problems] The technical measures taken to solve the problems are as follows.

As a method of manufacturing an SOI substrate which is a semiconductor device, an oxide film is formed on a wafer which is a substrate of the SOI substrate, a resist is applied, the oxide film other than the wafer surface is removed, and the resist is removed to remove the substrate. Fabricate a straight wafer.

Next, the wafer of the substrate and the front and back surfaces are mirror-finished, and after the wafer is cleaned, hydrophilic treatment is performed, and then hydrogen bonding is used to perform heat treatment to bond the wafers. This is a method of manufacturing a semiconductor device in which a resist is applied to a substrate wafer, the front surface side is etched to a constant thickness, and the resist is removed to manufacture an SOI substrate.

[0013]

In the manufacture of the SOI substrate, after the wafer and the wafer to be the substrate are bonded together, a resist is applied to the back surface of the wafer using an etching solution in which a small amount of iodine is added to succin fluoride nitrate as an additive. , The silicon part can be removed by etching, and the surface can have sufficient flatness, so that there is no need for complicated processes such as conventional mechanical rough polishing and polishing. .

EXAMPLES Examples will be described below.

FIGS. 1A to 1H show the manufacturing process of an SOI substrate.

A wafer 1 which is a substrate of an SOI substrate is oxidized to form an oxide film 2 as shown in FIG.

Next, the resist 3 is applied to the wafer surface (c), the oxide film other than the wafer surface is removed, and then the resist is removed. This is shown in (d). The straight wafer 4 is completed.

Next, the wafer 4 serving as the substrate of the SOI substrate and the wafer 5 having both front and back surfaces mirror-finished are H ₂
O ₂ —H ₂ SO _{4 was} washed, and a hydrophilic treatment was performed to make use of the fact that a hydroxyl group (—OH) is hydrogen-bonded.
Heat treatment is performed at ₂ ° C. for ₂ hrN ₂ to complete the connection between the wafers, which is shown in (e).

Next, a resist 6 is applied to the wafer 4 which will be the substrate of the SOI substrate (f), and HNO ₃ is applied to the front surface side.
Part of 7 is etched to a predetermined thickness using an etching liquid prepared by adding a small amount of I ₂ as an additive to —HF—CH ₃ COOH. This is shown in (g).

Next, the resist 6 is removed, and the SOI substrate 8 is completed. This is shown in (h).

By manufacturing the SOI substrate by the above method, the wafer after bonding can be polished only by chemical polishing with an etching solution, and the step of mechanical polishing can be omitted.

[0022]

[Effect] In the manufacture of the SOI substrate of the present invention, the mechanical polishing step is omitted, the process control is easy, and the etching liquid is used for polishing, so that there is little variation in the etching thickness between wafers and a large amount of processing is possible. Therefore, a simpler device can be used as compared with the mechanical polishing, and the cost can be greatly reduced.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of the present embodiment, in which (a) to (h) are explanatory diagrams in the order of each step.

FIG. 2 is an explanatory diagram of a conventional example, in which (a) to (e) are explanatory diagrams in the order of steps.

[Explanation of symbols]

 1 Silicon Wafer 2 Oxide Film 3 Resist 7 Etching Part 8 SOI Wafer 9 SOI Substrate Wafer 10 Double Sided Mirror Wafer 11 Grinding Part 12 Etching Part 13 Grinding Part

Claims (1)

[Claims] 1. As a method of manufacturing an SOI substrate which is a semiconductor device, an oxide film is formed on a wafer to be a substrate of an SOI substrate, and resist coating, oxide film removal and resist removal are performed to manufacture a substrate wafer. Next, the wafer of the substrate and the wafer whose front and back surfaces are both mirror-finished are subjected to a hydrophilization treatment, and then hydrogen bonding is used to perform a heat treatment to bond the wafers to each other. The wafer is coated with resist, the surface side is etched to a certain thickness, and the resist is removed to remove the SOI.
A method of manufacturing a semiconductor device for manufacturing a substrate.