JPH01260841A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To form a channel stopper of the same width as the width of an opening in an oxidation resisting film, by forming an oxide film mask at the outer surface part of a channel stopper region, and making an impurity-ion implanting region for the channel stopper narrower than the channel stopper region by using the mask. CONSTITUTION:The unnecessary part of an oxide film 61 is removed by anisotropic etching. Then an oxide film mask 6 is formed. Namely, the oxide film mask 6 is deposited on the side wall of an oxide film mask 3 and on the outer part of a channel stopper region C. Then, impurities for a channel stopper, e.g., boron ions for the channel stopper, are implanted into the surface of a pad 2 of the channel stopper which is exposed on the inside of the oxide film mask by an ion implanting method. Thus, a P<+> layer 42 is formed. Then, the oxide film mask 6 is removed by wet etching. Thereafter, a field oxide film 4 having a thickness of about 6,000Angstrom is formed by a wet oxidation method at, e.g., 900 deg.C. Thus, a channel stopper 51 is completed. In this way, the stopper becomes narrower than the width of a channel stopper 5 formed by conventional technology.

Description

[Detailed Description of the Invention] [Summary] Regarding a method for forming a channel stopper for isolation between elements in a semiconductor device, the present invention relates to a method of forming a channel stopper for isolation between elements in a semiconductor device, and the present invention relates to a method of forming a channel stopper for isolation between elements in a semiconductor device. A step of forming a silicon film, a step of forming an oxidation-resistant mask to define a region where a field oxide film is to be formed on the silicon oxide film, and a step of depositing a mask material to be an ion implantation mask by vapor phase growth. a step of anisotropically etching the material to leave it on the inner wall of the opening of the oxidation-resistant mask; a step of ion-implanting impurity for a channel stopper into the opening to form an ion-implanted layer; The method is characterized in that it includes a step of removing a mask material and a step of forming a field oxide layer by a thermal oxidation method.

[Industrial application field]

The present invention relates to a method for forming a channel stopper for isolation between elements in a semiconductor device.

In recent years, as the capacity of memory systems has increased, there has been a demand for higher integration of semiconductor devices. Therefore, it is necessary to miniaturize the element isolation region and the element isolation channel stopper region formed on the silicon substrate.

[Conventional technology]

FIG. 3 is a sectional view of a channel stopper according to the prior art, and FIGS. 4(a) to (=) are explanatory diagrams of the main steps for manufacturing the channel stopper shown in FIG. 3.

In FIG. 3, a silicon oxide film 2 is grown on the surface of a single crystal silicon substrate l, and a nitride film (St.

A field oxide layer (silicon thermal oxide film) 4 and a channel stopper (P
"layer or N" layer) 5 is provided.

In FIG. 4(A), after a thermally oxidized silicon film 2 is formed on the surface of a single crystal silicon substrate 1, a nitride film 3I is deposited thereon as shown in FIG. 4(U), and a channel stopper is formed. By removing portions of the nitride film 31 corresponding to region C, the oxidation-resistant mask 3 shown in FIG. 4(c) is formed.

Next, an impurity for a channel stopper, for example, boron, is ion-implanted to form a P'' layer 41 shown in FIG. 4(d).

Thereafter, a thermal oxidation treatment is performed to form a field oxide layer 4 in the channel stopper region C, as shown in FIG. 3, thereby completing a channel stopper 5 in which the ion implantation layer 41 is expanded with field oxidation N4.

[Problem to be solved by the invention]

The conventional channel stopper 5 manufactured as described above was manufactured by forming an ion implantation layer 51 over the entire surface of the channel stopper region C defined by the oxidation-resistant mask 3. Therefore, when the field oxide layer 4 is heated and formed, the impurity atoms implanted prior to the formation of the field oxide N4 spread outside the field oxide layer 4 within the substrate 1 by thermal diffusion, thereby forming a channel. The width W1 of the stopper 5 is W, where W is the width of the channel stopper region C (the opening width of the oxidation-resistant mask 3).
, >W.

Therefore, the effective element formation areas A + , A ! is W
.

-W, the threshold voltage vth of the transistor increases, and miniaturization of the MO3I transistor element is hindered.

An object of the present invention is to form a channel stopper with a width comparable to the opening width of the oxidation-resistant film, thereby eliminating the above-mentioned problems.

[Means to solve the problem]

According to the embodiment shown in FIG. 1, the method of the present invention includes the steps of forming a silicon oxide film 2 on the surface of a single crystal silicon substrate 1, and defining a region where a field oxide film 4 is to be formed on the silicon oxide film 2. a step of forming an oxidation-resistant mask 3; a step of depositing a mask material that will become an ion implantation mask by vapor phase growth; and a step of anisotropically etching the material to leave it on the inner wall of the opening of the oxidation-resistant mask. , a step of ion-implanting an impurity for a channel stopper into the opening to form an ion-implanted N42, and a step of removing the mask material. An oxide film mask is formed, and the ion-implanted region for the channel stopper impurity is made narrower than the channel stopper region by the mask, and as a result, the channel stop layer formed by forming the field oxide layer has the same extent as the field oxide layer. The field oxide layer is formed in a region narrower than the conventional one, which is formed wider than the field oxide layer, making it possible to achieve higher integration of semiconductor devices.

〔Example〕

Examples of the method of the present invention will be described below with reference to the drawings.

1(A) to 1(H) are diagrams for sequentially explaining the main steps of manufacturing a channel stopper according to an embodiment of the present invention, and FIG. 2 is a diagram showing a channel stopper manufactured by the steps shown in FIG. 1. FIG. 3 is a cross-sectional view of the region.

In FIG. 1, in which the same reference numerals are used for parts common to those in FIG. 3, as shown in FIG. After growing to a thickness of 300 people, the
), a nitride film 31 is deposited on the silicon oxide film 2 to a thickness of, for example, 2000 mm.

Next, as shown in FIG. 1(c), the nitride film 31 corresponding to the channel stopper region C is removed by photolithography and an oxidation-resistant mask 3 is formed, and then the nitride film 31 corresponding to the channel stopper region C is removed by vapor phase epitaxy. D) An oxide film 61 is deposited. However, the thickness of the oxide film 61 is determined in consideration of the redistribution of impurities when forming the field oxide layer 4. The spread is about 0.3 μm, and the thickness of the oxide film 61 is about 3,000 people.

Next, unnecessary portions of the oxide J161 are removed by anisotropic etching to form an oxide film that adheres to the oxide film mask 6 of FIG. After the mask 6 is formed, impurities for a channel stopper, such as boron for a channel stopper, are doped on the pad 2 surface of the channel stopper region C exposed inside the oxide film mask 6 by ion implantation at an implantation energy of 25 keV. Amount of 5 x 10"cm4 is injected to form a P"M42 shown in FIG.

Next, as shown in FIG. 1(G), after removing the oxide film mask 6 by wet etching, the
The wet oxidation method heated to
When field oxide film 4 is formed as shown in FIG. 1 (h), channel stopper 51 is completed.

The width W2 of the channel stopper 51 formed in this way is approximately the same as the width of the field oxide film 4, as shown in FIG.
narrower than 1.

〔Effect of the invention〕

As explained above, according to the method of the present invention, an oxide film mask is formed on the outer periphery of the channel stopper region, and the ion-implanted region of the channel stopper impurity is formed by the mask.
As a result, the channel stopper after forming the field oxide layer is narrower than the conventional channel stopper which is formed in the same area as the field oxide layer and spreads out from the field oxide layer. This has the effect of suppressing the rise in threshold voltage and enabling higher integration of semiconductor devices and miniaturization of forming elements.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the main steps according to an embodiment of the present invention, FIG. 2 is a sectional view of a channel stopper manufactured by the process shown in FIG. 1, and FIG. 3 is a sectional view of a channel stopper according to the prior art. FIG. 4 is an explanatory diagram of the main steps of manufacturing the channel stopper shown in FIG. 3. In the figure, ■ is a single crystal silicon substrate, 2 is a silicon oxide film, 3 is an oxidation-resistant mask, 4 is a field oxide layer, 6 is an oxide film mask, 42 is an ion implantation layer, 51 is a channel stopper, 61 is an oxide film An oxide film for forming a mask, C is a channel stopper region, and W is a width of the channel stopper region. Barring Akira -Real College ( - Yoga Lord -Character ρ Kitaro Polar Rod
1st bite 2nd bite! Conventionally, the rear elbow of Jronaya Kaya Rusu F.N.

Claims (1)

[Claims] A silicon oxide film (
2) and forming a field oxide film (4) on the silicon oxide film (2).
a step of forming an oxidation-resistant mask (3) that defines a region where the ion implantation mask will be formed; a step of depositing a mask material that will become an ion implantation mask by vapor phase growth; and anisotropically etching the material to form the oxidation-resistant mask (3). a step of leaving the mask material on the inner wall of the opening of the mask; a step of ion-implanting an impurity for a channel stopper into the opening to form an ion-implanted layer (42); a step of removing the mask material; and a step of removing the mask material by a thermal oxidation method. A method for manufacturing a semiconductor device, comprising the step of forming a field oxide layer (4).