JPS5849027B2 - Manufacturing method for semiconductor integrated circuit devices - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor device in which a large number of semiconductor devices are integrated to form a required circuit using a common silicon substrate, and in this case, semiconductor devices adjacent to each other on the main surface side of the silicon substrate are integrated. The present invention relates to a method for manufacturing a semiconductor integrated circuit device in which a silicon oxide film (which can be used, for example, as an insulating layer for isolation between elements) is formed in a manner that extends between the elements.

Conventionally, as shown in FIG. 1, this type of semiconductor integrated circuit device has been manufactured using a so-called CVD method to deposit a first layer on the main surface 2 of a silicon substrate, which is generally indicated by the reference numeral 1 in FIG. 1A, prepared in advance. As shown in FIG. 1C, an oxidation-resistant film 3 made of Si3N+ is formed, and then the oxidation-resistant film 3 is selectively etched, as shown in FIG. Then, by thermal oxidation treatment of the silicon substrate 1 using the mask layer 4 as a mask, as shown in FIG. A silicon oxide film 5 made of Si02 is formed, and then the area under the mask layer 4 of the silicon substrate 1 is used as a semiconductor element formation area 6, and the mask layer 4 is formed in the semiconductor element formation area 6 as shown in FIG. 1E. As shown, after removing from the main surface 2 of the silicon substrate 1, a required semiconductor region (not shown) constituting a required semiconductor element is removed from the main surface 2.
A manufacturing method has been proposed that includes a step of forming from the side to obtain a desired semiconductor integrated circuit device.

However, in the case of the conventional manufacturing method, since the mask layer 4 is a mask layer made of an oxidation-resistant film and has a relatively small difference in coefficient of thermal expansion from the silicon substrate 1, it is difficult to form the silicon oxide film 5. This method sometimes causes crystal distortion in the semiconductor element forming region 6, which has the disadvantage that a semiconductor element constructed using the semiconductor element forming region 6 cannot have expected good characteristics.

Furthermore, as shown in FIG. 2, a silicon substrate 2 (generally indicated by reference numeral 1 in FIG. 2A) prepared in advance is coated with <Si02> as shown in FIG. A silicon oxide film 7 made of the above and an oxidation resistant film 3 made of Si3N4 are laminated in that order, and then the oxidation resistant film 3 and the silicon oxide film 7 are selectively etched to form the structure shown in FIG. 2C. As shown in FIG. 2, a plurality of laminated mask layers 10 are formed by laminating a mask layer 8 made of a silicon oxide film 7 and a mask layer 9 made of an oxidation-resistant film 3 exactly overlaid thereon in this order, and then By thermal oxidation treatment of the silicon substrate 1 using the uniform laminated mask layer 10 as a mask, a relatively thick silicon oxide film is formed in the area other than under the laminated mask layer 10 on the main surface 2 side of the silicon substrate 1, as shown in FIG. 2D. After that, the area under the laminated mask layer 10 of the silicon substrate 1 is set as a semiconductor element formation area 6, and the laminated mask layer 10 is formed on the silicon substrate 1 within the semiconductor element formation area 6 as shown in FIG. 2E. The desired semiconductor integrated circuit device is obtained by removing the semiconductor device from the main surface 2, and then forming a required semiconductor region (not shown) constituting a required semiconductor element from the main surface 2 side. A manufacturing method has also been proposed.

However, in the case of such a conventional manufacturing method, the laminated mask layer 10
has a structure in which a mask layer 8 made of a silicon oxide film and a mask layer 9 made of an oxidation-resistant film are laminated on the silicon substrate 1 in that order, and the mask layer 9 made of the oxidation-resistant film and the silicon Even if the difference in thermal expansion coefficient between the silicon oxide film and the silicon substrate 1 is relatively small, the difference in thermal expansion coefficient between the silicon oxide film mask layer 8 and the silicon substrate 1 is sufficiently small. Although it is possible to avoid the drawback of the conventional case described above in FIG. 1 that crystal distortion occurs in the semiconductor element formation region 6 when the film 5 is in the form of a silicon oxide film, the presence of the mask layer 8 made of a silicon oxide film When the silicon oxide film 5 is formed on the silicon substrate 1, the silicon oxide film is formed on the silicon substrate 1.
Therefore, the silicon oxide film 5 is formed to have a so-called birth beak that extends to below the laminated mask layer 10, thereby making the silicon oxide film 5 finer. Therefore, it has the disadvantage that it is a major hindrance to increasing the density of semiconductor integrated circuit devices as a whole.

Furthermore, as conventionally shown in FIG. 3, a main surface 2 of a silicon substrate, generally indicated by reference numeral 1 in FIG. 3A, prepared in advance.
As shown in FIG. 3B, SiO2
A silicon oxide film 7 is formed, and then a plurality of mask layers 8 are formed by the silicon oxide film 7 as shown in FIG. 3C by a selective etching process on the silicon oxide film 7. Next, as shown in FIG. 3D, an oxidation-resistant film 3 made of Si3N is formed on the main surface 2 of the silicon substrate 1 by a so-called CVD method, covering the mask layer 8 and continuously extending. By selectively etching the coating 3, as shown in FIG. 3E, the oxidation-resistant coating 3 forms a portion 9a on the surface of the mask layer 8 opposite to the silicon substrate 1 side, and a side surface of the mask layer 8 connected thereto. A plurality of mask layers 9 are formed each covering a plurality of mask layers 8 consisting of a portion 9b and a portion 9C on the main surface of the silicon substrate 1 connected thereto, and then these mask layers 9 are used as a mask. As shown in FIG. 3F, a relatively thick silicon oxide film 5 is formed on the main surface 2 of the silicon substrate 1 by thermal oxidation treatment on the silicon substrate 1 in a region other than under the mask layer 9, and then the silicon substrate 1 is heated. The area under the mask layer 9 is the semiconductor element forming area 6.
After removing the mask layers 9 and 8 as shown in FIG. A manufacturing method including a step of forming a semiconductor integrated circuit device to obtain a desired semiconductor integrated circuit device has also been proposed.

In the conventional manufacturing method, a mask layer 9 made of an oxidation-resistant film is formed on a mask layer 8 made of a silicon oxide film formed on a silicon substrate 1, and this mask layer 8 is covered with a silicon oxide film. By extending the silicon oxide film 5 to the top of the substrate 1, the drawback that the silicon oxide film 5 is formed with a so-called bird's beak as in the case of the conventional manufacturing method described above with reference to FIG. 2 can be avoided. Gain,
Furthermore, since the mask layer 9 has a portion 9c that can be extended over the main body 2 of the silicon substrate 1, a semiconductor element forming region 60 portion 9c is formed.
Even if crystal distortion occurs in the region below, if the area of the portion 9c is made sufficiently small and the area of the region occupied under the semiconductor element forming region 60 portion 9c is made sufficiently small compared to the area of other regions, the semiconductor element can be formed. The problem of crystal distortion in region 6 can be substantially avoided.

However, since it is necessary to form a mask layer 9 that covers the mask layer 8 formed on the main surface of the silicon substrate 1 and extends onto the silicon substrate 1, the process of obtaining the mask layer 8 by selective etching treatment, that is, using a mask, is necessary. It requires a step of obtaining the mask layer 8 by patterning and a step of obtaining the mask layer 9 by patterning, and when obtaining the latter mask layer 9 by patterning, alignment with the mask layer 8 is required during the patterning. Therefore, it has the disadvantage that it is difficult to obtain a fine silicon oxide film 5.

Therefore, the present invention proposes a novel method for manufacturing a semiconductor integrated circuit device free from the above-mentioned drawbacks, which will become clear from the detailed description below.

FIG. 4 shows an example of a method for manufacturing a semiconductor integrated circuit device according to the present invention. Corresponding parts to those in FIGS. 1 to 3 are denoted by the same reference numerals. For example, C
A silicon oxide film T made of <Sin2 and an oxidation-resistant film 3 made of Si3N4 are formed by the VD method as shown in FIG. 4B.
are formed by stacking them in that order, and then the oxidation-resistant coating 3 and the silicon oxide coating 7 are formed using a common mask for each separate or common selection for them. A plurality of laminated mask layers 10 are formed by laminating, in this order, a mask layer 8 made of a silicon oxide film 7 and a mask layer 9 made of an oxidation-resistant film 3 exactly overlapping with the mask layer 8, as shown in FIG. 4C, by selective etching treatment. form.

Next, as shown in FIG.
An oxidation-resistant film 11 made of Si3N4 that is continuously extended on the main surface 2 of the main surface 2 other than under the laminated mask layer 10 is formed all at once, and then the oxidation-resistant film 11 is subjected to sputter etching treatment and reactive spacing. If directional etching treatment such as ivy etching treatment is performed, the portion of the oxidation-resistant coating 11 having a surface extending parallel to the main surface 2 of the silicon substrate 1, that is, the side opposite to the silicon substrate 1 side of the laminated mask layer 10 , and the portion that extends onto the main surface 2 of the silicon substrate 1 has a higher speed than the portion that has the surface that extends perpendicularly to the main surface 2 of the silicon substrate 1, and thus the portion that extends onto the side surface of the laminated mask layer 10. In view of the fact that the oxidation-resistant film 11 is etched by the process, a directional etching process is performed on the oxidation-resistant film 11 without patterning, leaving only the part on the side surface of the laminated mask layer 10 and removing the other part. Thus, a laminated mask layer 13 having a structure as shown in FIG. form a plurality.

Next, by thermal oxidation treatment of the silicon substrate 1 using the laminated mask layer 13 as a mask, a silicon oxide film 5 is formed on the area other than under the laminated mask layer 13 on the main surface 2 side of the silicon substrate 1, as shown in FIG. 4F. After that, a silicon substrate 1 is formed.
The area under the laminated mask layer 13 is defined as a semiconductor element formation area 6, and the laminated mask layer 13 is formed in the semiconductor element formation area 6.
as shown in FIG. 4G from the main surface 2 of the silicon substrate 1, and then forming a required semiconductor region (not shown) constituting a required semiconductor element from the main surface 2 side. A desired semiconductor integrated circuit device is obtained.

The above is an example of the manufacturing method of the semiconductor integrated circuit device according to the present invention. According to this manufacturing method, the laminated mask layer 13 used as a mask when forming the silicon oxide film 5 is the mask layer 8 made of a silicon oxide film. A structure in which a mask layer 12 made of an oxidation-resistant film is continuously extended to reach the main surface 2 of the silicon substrate 1 on the side surface of a laminated mask layer 10 formed by laminating the mask layer 9 made of an oxidation-resistant film and the mask layer 9 made of an oxidation-resistant film. Therefore, the configuration of the mask layers 9 and 12 made of the oxidation-resistant coating that constitutes the laminated mask layer 13 corresponds to the mask layer 9 in the conventional manufacturing method described above in FIG. Similar to the conventional manufacturing method shown in FIG. 3, the drawback that the silicon oxide film 5 is formed with a so-called bird's beak as in the conventional manufacturing method shown in FIG. This can be avoided, and the problem of crystal distortion in the semiconductor element forming region 6 due to the shape of the silicon oxide film 5 can also be substantially avoided.

However, as shown in FIG. 3, mask layers 9 and 12 made of an oxidation-resistant film corresponding to mask layer 9 in the conventional manufacturing method described above are shown in FIG.
The laminated mask layer 13 having the following structure can be obtained by a simple process of obtaining the laminated mask layer 10, then forming the oxidation-resistant coating 11, and then subjecting it to a directional etching treatment. Since the process includes a single patterning process in which a selective etching process is performed to obtain the laminated mask layer 10, the process does not have the drawbacks of the conventional manufacturing method described above in FIG. This method has the unique feature that the silicon oxide film 5 can be easily obtained in a fine structure.

In the above description, the laminated mask layer 13 used as a mask for forming the silicon oxide film 5 is different from the laminated mask layer 1.
The laminated mask layer 10 has a structure in which a mask layer 12 formed by an oxidation-resistant coating 11 is continuously extended on the side surface of the mask layer 9. Although the detailed explanation is omitted, as shown in FIG. 5A corresponding to FIG. Then, as shown in FIG. 5B corresponding to FIG. 4D, an oxidation-resistant coating 11 is formed, and then the oxidation-resistant coating 11 is By directional etching without patterning, as shown in FIG. 5C corresponding to FIG. The laminated silicon layer 13 is formed as shown in FIG. 6A, which corresponds to FIG. , the mask layer 12 constituting it can be extended onto the side surface of the mask layer 8 to reach the main surface 2 of the silicon substrate 1, but not onto the side surface of the mask layer 9. Figure 5 D or 6 corresponding to Figure 4 F
As shown in FIG. B, a silicon oxide film 5 is formed in the same manner as described above in FIG. 4F, and then a laminated mask layer is formed as shown in FIG. 5E or FIG. It is also possible to obtain the desired semiconductor integrated circuit device by removing 13, and it will be clear that the same characteristics can be obtained as shown in FIG. 4 in this case.

Furthermore, in the above description, the silicon oxide film 5 is laminated as a mask layer 13.
Although we have described the case in which the mask layer 13 is formed by thermal oxidation treatment on the silicon substrate 1 which serves as a mask, the detailed explanation thereof will be omitted, but the laminated mask layer 13 is formed as shown in FIG. 7A corresponding to FIG. 4E. After that, using this as a mask, the silicon substrate 1 is anodized to form a porous silicon film 14 in a region other than under the laminated mask layer 13 on the main surface 2 side of the silicon substrate 1, as shown in FIG. 7B. Then, a thermal oxidation treatment is performed using the laminated mask layer 13 as a mask to form a silicon oxide film 15 formed by oxidizing the porous silicon layer 14 as shown in FIG. 7C, as described above in FIG. A silicon oxide film is formed in place of the silicon oxide film 5, and then a laminated mask layer 1 is formed as shown in FIG. 7D corresponding to FIG. 4G.
It is also possible to obtain the desired semiconductor integrated circuit device by removing 3, and it will be clear that the same characteristics can be obtained as described above with reference to FIG.

Further, in the above description, the case where only the silicon oxide film 5 is formed in the steps before forming the semiconductor element in the semiconductor element shaped region 6 has been described, but a detailed explanation thereof will be omitted, but the fourth The laminated mask layer 10 is used as a mask between the step of forming the laminated mask layer 10 as described above in FIG. The silicon substrate 1 is introduced into the silicon substrate 1 in a region other than under the laminated mask layer 10 on the main surface side of the silicon substrate 1 as shown by the dotted line in FIG. 4C. A step of forming a semiconductor region 20 having the same conductivity type as , or forming a laminated mask layer 13 as described above with reference to FIG.
During the step of forming the silicon substrate 1, an impurity is introduced into the silicon substrate 1 using the laminated mask layer 13 as a mask, and the main surface of the silicon substrate 1 is formed as shown by the chain line in FIG. 4E. A semiconductor region 21 having the same conductivity type as the silicon substrate 1 is formed in a region other than under the laminated mask layer 13 on the side, thereby forming a semiconductor element shaped region 6 as shown by dotted lines or chain lines in FIGS. 4F and G. A so-called channel cut layer 22 or 23 is formed around the region of the silicon oxide film 5 that can be extended into the silicon substrate 1 based on the semiconductor region 20 or 21 in a step before forming a semiconductor element therein. It can also be done to obtain the configuration.

Although illustrations and explanations are omitted, there are a step of forming the laminated mask layer 10 as described above with reference to FIG. 4C, and a step of forming the oxidation-resistant film 11 as described above with reference to FIG. 4E, or as described above in FIG. 4E.
Between the step of forming the silicon oxide film 5 and the step of forming the silicon oxide film 5 as described above with reference to FIG. As described above in FIG. 4F, immediately before the step of forming the silicon oxide film 5, the surface of the silicon substrate 1 on the side of the laminated mask layer 13 is formed so that the surface of the area other than under the laminated mask layer 13 is The surface of the region below the laminated mask layer 13 is set to the side opposite to the laminated mask layer 13 side, so that the silicon oxide film 5 has a surface opposite to the silicon substrate 1 side and the laminated mask layer 13 side. It is formed so that there is substantially no step difference or a small step difference between the region and the surface portion of the region, and a required semiconductor in a large number of semiconductor elements formed using the silicon substrate 1 is formed. It is also possible to form a wiring layer that extends the elements onto the silicon substrate 1 so that the wiring layer can be reliably formed when configuring a required circuit.

Further, in the above description, the case where the oxidation-resistant film is made of Si3N4 has been described, but even if it is made of SiC or Al203, the above-mentioned features of the present invention can be obtained, and other aspects can be obtained without departing from the spirit of the present invention. Various modifications could be made.

[Brief explanation of drawings]

1, 2, and 3 are schematic cross-sectional views showing sequential steps of a conventional method for manufacturing a semiconductor integrated circuit device, and FIG. 4 shows a method for manufacturing a semiconductor integrated circuit device according to the present invention. 5, 6, and 7 are schematic cross-sectional views in the sequential steps showing the process of manufacturing the semiconductor integrated circuit device according to the present invention. It is a schematic cross-sectional view. In the figure, 1 is a silicon substrate, 2 is a main surface, 3 is an oxidation-resistant film, 5 and 15 are silicon oxide films, 6 is a semiconductor element formation region, 7 is a silicon oxide film, 8, 9 and 12 are masks Layers 10 and 13 are laminated mask layers, and 14 is a porous silicon film, respectively.

Claims (1)

[Claims] 1. Laminating a silicon oxide film and a first oxidation-resistant film in that order on the main surface of a silicon substrate;
The first oxidation-resistant coating and the silicon oxide coating are selectively etched to form a first mask layer of the silicon oxide coating and a second mask layer of the first oxidation-resistant coating, etc. a step of forming a laminated first laminated mask layer; and on the surface and side surface of the first laminated mask layer opposite to the silicon substrate side, and on the first laminated mask layer of the silicon substrate. A step of forming a second oxidation-resistant film that can be connected and extended on a region other than the bottom, and an etching process without patterning on the second oxidation-resistant film, forms the above-mentioned on the side surface of the first laminated mask layer. forming a second laminated mask layer formed by connecting and extending the mask layers that reach the main surface of the silicon substrate with a second oxidation-resistant film; and forming the second laminated mask layer as a mask. forming a silicon oxide film in a region other than under the second laminated mask layer on the main surface side of the silicon substrate by oxidizing the silicon substrate. .