JPH04240748A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To easily form a separation of a microscopic element upon high integration of a semiconductor integrated circuit. CONSTITUTION:A step 100 of 0.5mum in depth was formed on a semiconductor substrate 11 by lithography technique and anisotropic dry etching (Fig. 1(b)). A first oxide film 13 was formed 0.03mum thick on the substrate 11 by thermal oxidation, and further a second oxide film 14 was deposited 0.5mum thick thereon by a chemical vapor depositing method (Fig. 1(c)). The first and second films were anisotropically dry etched until the surface of the substrate 11 is exposed, a sidewall 14A of an insulator was formed on the sidewall of the step of the substrate, and a microscopic element could be easily separated (Fig. 1(d)). After the element is separated, the upper stage, the lower stage of the step of the substrate are used as active regions as they are to form the element (Fig. 1(e)).

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device that improves fine element isolation technology for semiconductor devices.

0002

2. Description of the Related Art An integrated circuit includes a plurality of active elements separated from each other by an insulating layer on a common semiconductor silicon substrate. Conventional LOCO
S (Local Oxidation of Sili
In the method of manufacturing a semiconductor device using the con) method, a semiconductor substrate is separated into an active region and a field region via a buried insulator, and an element is formed in the active region. Conventionally, the separation is performed by a selective oxidation method. This was done through the steps shown in Figure 3.

First, a silicon oxide film layer 31 is formed on the surface of a semiconductor silicon substrate 11, and a silicon nitride film layer 32 is further formed on the silicon oxide film layer (FIG. 3(a)).
. Next, using lithography technology and dry etching technology, the silicon nitride film layer and silicon oxide film layer are selectively removed, the semiconductor silicon substrate is selectively exposed, and an oxidation-resistant mask layer is formed on the planned active area. (Fig. 3(b)). Next, oxidation is performed by heat treatment at a constant temperature for a certain period of time in an oxidizing atmosphere to form a thick field oxide film 33 deeply buried in the semiconductor silicon substrate (FIG. 3(c)). Next, the silicon nitride film layer and silicon oxide film layer on the active region are removed to expose the semiconductor silicon substrate surface and perform element isolation (FIG. 3(d)).

[0004] By the method described above, it is possible to perform element isolation using an insulating film of a semiconductor device. but,
The oxidation step in this method results in oxide growth at the outer periphery of the surface of the active region as a result of the lateral movement of oxygen through the thin silicon oxide layer. The lateral oxide projections formed in this way are called bird's beaks. Due to the entry of this bird's beak,
The dimensions of the active area become smaller than the design dimensions. Therefore, the usable portion of the active area is reduced.

[0005]

[Problems to be Solved by the Invention] As described above, in this conventional manufacturing method, as shown in FIG. Largely, as shown in (Figure 3(d)),
The active area becomes narrower. Therefore, as the device becomes finer, the finished active region becomes very narrow or it becomes impossible to form an active region due to the lateral invasion of the field oxide film. If the field oxide film is made thinner, the penetration of bird's beaks can be reduced, but sufficient element isolation characteristics cannot be obtained. Therefore, the conventional LOCOS method has the disadvantage that there is a limit to the miniaturization of elements, which is a major obstacle to increasing the degree of integration of semiconductor integrated circuit devices.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a method for manufacturing a semiconductor device that achieves fine element isolation.

[0007]

[Means for Solving the Problems] The present invention includes a step of forming an etching-resistant mask on a semiconductor substrate by lithography technology, a step of etching the semiconductor substrate to form a stepped portion, and a step of removing the etching-resistant mask. do,
forming an oxide film by thermally oxidizing the semiconductor substrate and depositing an insulating film; and performing anisotropic dry etching on the insulating film and the oxide film until the surface of the semiconductor substrate is exposed; The present invention provides a method for manufacturing a semiconductor device, comprising the step of forming an insulating sidewall on the sidewall of the stepped portion to serve as an element isolation region. Further, there is provided the method of manufacturing the semiconductor device described above, wherein the thickness of the insulating film is desirably set to be equal to or less than the depth of the step of the semiconductor substrate.

Furthermore, the present invention includes a step of forming an etching-resistant mask on a semiconductor substrate by a lithography technique, a step of etching the semiconductor substrate to form a stepped portion, and a step of removing the etching-resistant mask. , a step of forming an oxide film by thermally oxidizing the semiconductor substrate; and anisotropic dry etching of the oxide film until the surface of the semiconductor substrate is exposed, and forming an oxide film on the sidewall of the stepped portion of the semiconductor substrate. The present invention provides a method for manufacturing a semiconductor device, comprising the steps of forming sidewalls to serve as element isolation regions. Further, there is provided a method of manufacturing the semiconductor device described above, wherein the thickness of the oxide film is desirably set to be equal to or less than the depth of the step of the semiconductor substrate.

[0009]

[Function] The present invention uses the above-described semiconductor device manufacturing method to provide a step on a semiconductor substrate and form an insulating film sidewall on the side wall of the step to form an element isolation region, thereby easily forming fine element isolation. can do. Further, the depth of element isolation can be controlled by the depth of the step of the substrate, and the element isolation width can be easily controlled by the thickness of the insulating film. In particular, by making the thickness of the insulating film equal to or less than the depth of the step of the semiconductor substrate, element isolation regions can be formed more precisely and with better reproducibility than in the conventional LOCOS method. Further, after forming the element isolation region by the above-described manufacturing method, the steps can be simplified since the upper and lower step portions of the semiconductor substrate can be used as active regions to form the device. Therefore, by using the present invention, the process is simplified and it is effective in forming highly accurate and fine element isolation of semiconductor devices.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS A method of manufacturing a semiconductor device according to an embodiment of the present invention will be described below with reference to the drawings.

(FIG. 1) shows a process cross-sectional view of a method for manufacturing a semiconductor device according to an embodiment of the present invention. A resist pattern 12 was formed on a semiconductor silicon substrate 11 by lithography technology (FIG. 1(a)). Using the resist pattern 12 as a mask, a step 10 with a depth of 0.5 μm is formed on the semiconductor silicon substrate by anisotropic dry etching.
0 was formed and the resist pattern 12 was removed (FIG. 1(
b)). A first oxide film 13 with a thickness of 0.03 μm is formed on the surface of the semiconductor silicon substrate 11 by thermal oxidation, and a second oxide film 14 with a thickness of 0.5 μm is further formed thereon by chemical vapor deposition.
μm was deposited (Fig. 1(c)). The second oxide film and the first oxide film are anisotropically dry etched until the surface of the semiconductor substrate 11 is exposed, and a sidewall 14A made of an insulating material, mainly the oxide film 14, is formed on the sidewall of the stepped portion of the semiconductor substrate. An element isolation region was formed (FIG. 1(d)). After forming the element isolation region, elements such as MOS transistors can be formed using the upper and lower step portions of the semiconductor substrate as active regions (FIG. 1(e)). 15 is a source and drain region of a MOS transistor, 16 is a gate electrode, and 17 is a gate oxide film.

As described above, according to this embodiment, a step is provided on the semiconductor substrate, and an oxide film sidewall is formed on the side wall of the step to form an element isolation region, so that fine element isolation can be easily formed. I was able to do that. In particular, in this example, the thickness of the oxide film was made to be approximately the same as the depth of the step of the semiconductor substrate, so that fine element isolation regions could be formed with good reproducibility and high precision. In addition, after forming the element isolation region,
Since elements can be formed using the upper and lower portions of the semiconductor substrate as active regions, the process is simplified.

In this embodiment, the oxide film was deposited by chemical vapor deposition, but other insulators may be deposited. Furthermore, although the thickness of the oxide film is set to be approximately the same as the depth of the step of the semiconductor substrate, it may be less than the depth of the step.

A second embodiment of the present invention will be described below with reference to the drawings. (FIG. 2) shows a process cross-sectional view of a method for manufacturing a semiconductor device in an embodiment of the present invention. By lithography technology, semiconductor silicon substrate 1
A resist pattern 12 was formed on 1 (FIG. 2(a))
. Using the resist pattern 12 as a mask, the semiconductor silicon substrate is etched to a depth of 0.5 μm by anisotropic dry etching.
A step 100 was formed, and the resist pattern 12 was removed (FIG. 2(b)). An oxide film 21 with a thickness of 0.5 μm was formed on the surface of the semiconductor silicon substrate 11 by thermal oxidation (Fig. 2
(c)). The oxide film 21 is anisotropically dry etched until the surface of the semiconductor substrate 11 is exposed, and an insulating sidewall 21A made of a part of the oxide film 21 is formed on the sidewall of the stepped portion of the semiconductor substrate to form an element isolation region. (Figure 2(d)
)). After forming the element isolation region, elements can be formed using the upper and lower steps of the semiconductor substrate as active regions (FIG. 2(e)).

As described above, according to this embodiment, a step is provided in the semiconductor substrate, and an oxide film sidewall is formed on the side wall of the step to form an element isolation region, so that fine element isolation can be easily formed. I was able to do that. In particular, in this example, the thickness of the oxide film was made to be approximately the same as the depth of the step of the semiconductor substrate, so that fine element isolation regions could be formed with good reproducibility and high precision. In addition, after forming the element isolation region,
Since elements can be formed using the upper and lower portions of the semiconductor substrate as active regions, the process is simplified.

In this embodiment, the thickness of the oxide film is made to be approximately the same as the depth of the step of the semiconductor substrate, but it may be less than the depth of the step.

[0017]

As explained above, according to the method of manufacturing a semiconductor device of the present invention, a step is provided on a semiconductor substrate, and a sidewall of an insulating film is formed on the side wall of the step to form an element isolation region. Fine element isolation can be easily formed. In particular, by making the thickness of the insulating film equal to or less than the depth of the step of the semiconductor substrate, fine element isolation regions can be formed with high reproducibility and high precision. Furthermore, after forming the element isolation region according to the present invention, the upper and lower portions of the step of the semiconductor substrate can be used as active regions to form elements, thereby simplifying the process. Therefore, by using the present invention, the process is simplified and it is effective in forming highly accurate and fine element isolation, so that it can greatly contribute to ultra-high density integrated circuits.

[Brief explanation of the drawing]

FIG. 1 is a process cross-sectional view of a method for manufacturing a semiconductor device in a first embodiment of the present invention.

FIG. 2 is a process cross-sectional view of a method for manufacturing a semiconductor device according to a second embodiment of the present invention.

FIG. 3 is a process cross-sectional view of a conventional method for manufacturing a semiconductor device.

[Explanation of symbols]

11 Semiconductor silicon substrate 12 Resist pattern 13 First oxide film 14 Second oxide film 14A side wall 15 Source/drain region 16 Gate 17 Gate oxide film 21A Sidewall 100 steps

Claims (4)

[Claims] 1. A step of forming an etching-resistant mask on a semiconductor substrate using lithography technology, a step of etching the semiconductor substrate to form a stepped portion, and removing the etching-resistant mask and heating the semiconductor substrate. a step of forming an oxide film by oxidation and depositing an insulating film; and anisotropic dry etching of the insulating film and the oxide film until the surface of the semiconductor substrate is exposed; 1. A method of manufacturing a semiconductor device, comprising the step of: forming an insulating sidewall to serve as an element isolation region. 2. The method of manufacturing a semiconductor device according to claim 1, wherein the thickness of the insulating film is set to be equal to or less than the depth of a step of the semiconductor substrate. 3. A step of forming an etching-resistant mask on a semiconductor substrate using a lithography technique, a step of etching the semiconductor substrate to form a stepped portion, and removing the etching-resistant mask and heating the semiconductor substrate. A step of forming an oxide film by oxidation, and anisotropic dry etching of the oxide film until the surface of the semiconductor substrate is exposed, forming sidewalls of the oxide film on the side walls of the stepped portion of the semiconductor substrate, 1. A method for manufacturing a semiconductor device, comprising the step of forming an isolation region. 4. The method of manufacturing a semiconductor device according to claim 3, wherein the thickness of the oxide film is set to be equal to or less than the depth of a step of the semiconductor substrate.