JPH05152427A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To form a dielectric isolation structure without causing a crystal defect regarding the manufacturing method of a semiconductor device which is provided with the dielectric isolation structure using an SOI substrate. CONSTITUTION:An SOI substrate is provided with a structure where a silicon substrate 1 for support use, a silicon oxide film 2, a silicon nitride film 3 and a silicon substrate 4 for element formation use have been laminated in this order. By using the SOI substrate, a silicon nitride mask 5 is formed in a region, where an element is to be formed, on the silicon substrate 4 for element formation use; parts other than the region, where the element is to be formed, on the silicon substrate 4 for element formation are oxidized completely by a selective oxidation method; they are changed into a silicon oxide layer 6. Thereby, an element isolation layer is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device having a dielectric isolation structure using an SOI substrate.

[0002]

2. Description of the Related Art A dielectric isolation structure in which a bottom surface and a peripheral side surface of an element are completely separated by an insulating film has a great advantage in improving a withstand voltage and reducing a parasitic capacitance of a semiconductor device, particularly a semiconductor integrated circuit device. Have.

FIG. 3 is a process explanatory view of a conventional semiconductor device manufacturing method. In this figure, 21 is a supporting silicon substrate, 22 is a silicon oxide film, 23 is an element forming silicon substrate, 24 is a silicon nitride mask, and 25 is a silicon oxide layer.

The conventional manufacturing process will be described with reference to this process chart. First step (see FIG. 3A) SOI in which an element forming silicon substrate 23 is bonded onto a supporting silicon substrate 21 with a silicon oxide film 22 interposed therebetween.
Form a substrate.

Second Step (See FIG. 3B) A silicon nitride mask 24 is formed on a device formation planned region on a device formation silicon substrate 23.

Third step (see FIG. 3C) The silicon nitride mask 24 formed in the previous step is used as an oxidation-resistant mask to perform thermal oxidation treatment until the silicon substrate 23 for element formation becomes completely silicon oxide. Silicon layer 25
To form. As a result, the element formation planned region 23 surrounded by the silicon oxide layer 25 remains under the silicon nitride mask 24, and the dielectric isolation structure is completed.

[0007]

However, when the dielectric isolation structure is formed by the conventional manufacturing method, there is a problem that crystal defects are likely to occur in the element forming silicon substrate. The cause of the occurrence of crystal defects will be described with reference to FIG.

As shown in FIG. 3C, when the element forming silicon substrate 23 is oxidized in the third step by the conventional method, not only the element forming silicon substrate 23 but also the supporting silicon substrate 21 through the silicon oxide film 22. The portion B on the surface of the will also be oxidized. When silicon is oxidized, its volume expands to about twice, so that a force acts to lift up the periphery C of the single crystal silicon region A forming the element.

As a result, a portion of the periphery C of the single crystal silicon region A is curved, and a large stress is generated in the single crystal silicon forming the element to cause a crystal defect. Therefore, the above-mentioned conventional technique has difficulties in practical use. It is an object of the present invention to provide a method for manufacturing a semiconductor device that can form a dielectric isolation structure without generating crystal defects.

[0010]

In the method of manufacturing a semiconductor device according to the present invention, a structure in which a supporting silicon substrate, a silicon oxide film 2, a silicon nitride film, and an element forming silicon substrate are laminated in this order is adopted. A step of forming an element isolation layer by using the SOI substrate having the element and converting the silicon plate for element formation other than the element formation planned region into a silicon oxide layer by a selective oxidation method was adopted.

[0011]

1 is an explanatory view of the principle of the method of manufacturing a semiconductor device according to the present invention. In this figure, 1 is a supporting silicon substrate, 2 is a silicon oxide film, 3 is a silicon nitride film, 4 is an element forming silicon substrate, 5 is a silicon nitride mask, and 6
Is a silicon oxide layer.

First, a supporting silicon substrate 1, a silicon oxide film 2, a silicon nitride film 3 and a device forming silicon substrate 4 are formed.
Is prepared, a silicon nitride film is formed on the entire surface of the SOI substrate by CVD, and the portion other than the element formation planned region is removed by the photolithography technique, leaving the silicon nitride mask 5 (FIG. 1A). reference).

Next, an oxidation treatment is added by keeping the temperature at a high temperature in an oxidizing atmosphere. By this oxidation treatment, the element forming silicon substrate 4 exposed on the outside of the silicon nitride mask 5 is oxidized to form a silicon oxide layer 6 having a thickness doubled. Since the silicon nitride film 3 is formed on the silicon nitride film 3, the surface of the supporting silicon substrate 1 is not oxidized through the silicon oxide film 2, and the force for lifting the element forming silicon substrate 4 does not work. Crystal defects do not occur in the element formation silicon substrate 4 remaining in the element formation planned region below (see FIG. 1B). The subsequent element forming process is the same as that of the conventional technique.

[0014]

FIG. 2 is an explanatory view of manufacturing steps of a method for manufacturing a semiconductor device according to an embodiment. In this figure, 11 is a supporting silicon substrate, 12 is a silicon oxide film, 13 is an element forming silicon substrate, 14 is a silicon nitride film, 15 is a silicon oxide film, 16 is a silicon nitride mask, and 17 is a silicon oxide layer. ..

The manufacturing method of this embodiment will be described with reference to the manufacturing process explanatory drawings. First step (see FIG. 2 (A)) A supporting silicon substrate 11 having a silicon oxide film 12 deposited on its surface, and an element forming silicon substrate 13 having a silicon nitride film 14 and a silicon oxide film 15 deposited on its surface, Bonding is performed by a well-known wafer bonding technique.

Second Step (See FIG. 2B) Next, the silicon substrate 13 for element formation is, for example, 0.5 μm by polishing (polishing) or chemical etching.
Thin. Then, after forming a silicon nitride film on the surface, patterning is performed to form a silicon nitride mask 16 in the element formation planned region.

Third step (see FIG. 2 (C)) The exposed silicon substrate 13 for element formation is completely oxidized by using the silicon nitride mask 16 as a mask to have a thickness of about 1 μm.
A silicon oxide layer 17 having a thickness of m is formed, and a dielectric isolation structure in which the device formation planned region is completely surrounded by the silicon oxide layer 17 is completed. After that, appropriate elements are formed in the element forming silicon substrate 13 by a normal integrated circuit manufacturing process.

[0018]

As described above, according to the present invention, it is possible to form a dielectric isolation structure that does not include crystal defects in the element formation planned region, which greatly contributes to the performance improvement of the semiconductor integrated circuit device.

[Brief description of drawings]

FIG. 1 is a diagram illustrating the principle of a method for manufacturing a semiconductor device according to the present invention.

FIG. 2 is a manufacturing process explanatory diagram of the semiconductor device manufacturing method according to the embodiment.

FIG. 3 is a process explanatory view of a conventional method for manufacturing a semiconductor device.

[Explanation of symbols]

 1 silicon substrate for support 2 silicon oxide film 3 silicon nitride film 4 silicon substrate for element formation 5 silicon nitride mask 6 silicon oxide layer

Claims (1)

[Claims] 1. An SOI substrate having a structure in which a supporting silicon substrate (1), a silicon oxide film (2), a silicon nitride film (3) and a device forming silicon substrate (4) are laminated in this order. And a step of forming a device isolation layer by converting a region other than a device formation planned region of the device forming silicon plate (4) into a silicon oxide layer (6) by a selective oxidation method. Method.