JPH02103951A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To suppress the occurrence of a bird's beak and to expand element forming regions by providing a compound forming rate larger than that in other parts by oxidizing isolating regions of Si single crystal layers after the formation of a polycrystal part or an amorphous part. CONSTITUTION:A single crystal Si 2 and SiO33 are provided on an insulating substrate 1. A window is provided at a region 4a corresponding to an element isolating region. Double-layer masks of Si3N44 having said region 4a and resist 5 are provided on the insulating substrate 1. Si ion beams B are implanted, and a specified region 2a is made amorphous. The entire resist 5 is removed, and annealing is performed at about 600 deg.C. Then the region 2a is made to be the polycrystalline region. Then, the entire resist is removed, and heat treatment is performed in O2. At this time, the compound forming rate of the polycrystalline or amorphous region 2a is larger than that of other single crystal regions. Therefore oxidization is made to progress quickly along the thickness. The occurrence of a bird's beak is effectively suppressed. Element isolating regions having the required thickness are formed. The element forming regions 2a and 2b are separated each other.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a semiconductor device, and in detail,
The present invention relates to a method of forming an element isolation region for separating the element formation walls from each other.

[Conventional technology]

Conventionally, a manufacturing method as shown step by step in FIG. 2 has generally been used to form an element region of a semiconductor device.

First, as shown in FIG. 2(a), a silicon single crystal layer 2 is formed on the surface of an insulating base if prepared in advance, and then a silicon oxide film 3 is grown by thermal oxidation on this silicon single crystal layer 2. Then, a silicon nitride film 4 is deposited thereon by CVD. And Fig. 2(b)
As shown in , after coating and forming a photoresist layer 5 on the silicon nitride film 4 and patterning it, using the remaining part of the patterned photoresist layer 5 as a mask, the silicon nitride film 4 is divided into elements N 9J (area and The corresponding predetermined area 4a is removed by etching.

Next, all remaining portions of the photoresist layer 5 are removed and the insulating substrate 1 is heat treated in an oxygen-containing gas atmosphere to form silicon nitride H4 as shown in FIG. 2(c). A predetermined region 2a of the silicon single crystal layer 2 is oxidized by a selective oxidation technique via a predetermined region 3a of the silicon oxide film 3 exposed below the predetermined region 4a. As a result, the predetermined region 2a of the silicon pre-crystalline layer 2 is oxidized and the predetermined region 3a of the silicon oxide film 3 is enlarged along the thickness direction and the lateral direction, resulting in the formation of a structure as shown in FIG. 2(d). Element isolation regions 6 made of silicon oxide, ie, an insulator, are formed to a required thickness.

At this time, the silicon oxide portions A and A that are formed by digging into the silicon nitride film 4 are called a bird's peak at -a.

[Problem to be Solved by the Invention] By the way, in the conventional method for manufacturing a semiconductor device, when heat treatment is performed in a gas atmosphere containing oxygen, the thickness of the insulator for separating the element regions becomes Bird's peaks A, A having a width of . Therefore, these bird's peaks A, A narrow the element formation tJIMU2b, 2b in the silicon single crystal layer 2, resulting in a disadvantage that high integration in the semiconductor device is hindered.

The present invention was devised to eliminate such inconveniences, and provides a method for manufacturing a semiconductor device that can suppress the occurrence of bird's peaks and expand the element formation area. It is an object.

[Means to solve the problem]

By the way, the bird's peak as mentioned above occurs due to the oxidation of single crystal silicon having good crystallinity, and the rate of compound formation between single crystal silicon and oxygen is low, that is, the rate of reaction between the two is slow. This is thought to be due to. Therefore, if polycrystalline or amorphous silicon, which has lower crystallinity than single-crystal silicon, is oxidized, the rate of compound formation in these materials is higher than that of single-crystal silicon, so Birds It is thought that it becomes possible to suppress the occurrence of peaks.

The method for manufacturing a semiconductor device according to the present invention has been made based on the above knowledge, and includes preparing an insulating substrate on which a silicon single crystal layer, a silicon oxide film, and a silicon nitride film are sequentially formed. forming and buttering a photoresist layer on the silicon nitride film, and removing a predetermined region of the silicon nitride film corresponding to an element isolation region using the remaining portion of the photoresist layer as a mask; irradiating an energy beam using the remaining portion of the silicon oxide film as a mask to polycrystallize or amorphize a predetermined region of the silicon single crystal layer that will become an element isolation region through the exposed region of the silicon oxide film; After removing the remaining portion of the resist layer, oxidizing the polycrystalline or amorphous region of the silicon single crystal layer by heat treatment in an oxygen-containing gas atmosphere to form an element isolation region; This includes:

[Effect]

According to the above manufacturing method, a predetermined region of a silicon single crystal layer that will become an element isolation region is made polycrystalline or amorphous by irradiation with an energy beam, and then a silicon single crystal layer is heat-treated in an oxygen-containing gas atmosphere. Polycrystalline or amorphous regions of the crystal layer are oxidized. Therefore, the polycrystalline or amorphous region in this silicon single crystal layer has a higher compound generation rate than other single crystal regions covered with the remaining silicon nitride film. As the oxidation reaction becomes faster, the occurrence of bird's peaks is suppressed.

〔Example〕

Hereinafter, a method for manufacturing a semiconductor device according to the present invention will be explained based on step-by-step process cross-sectional views shown in FIG. In FIG. 1 according to this embodiment, parts that are the same as or corresponding to those in FIG. 2 according to the conventional example described above are given the same reference numerals.

First, as shown in FIG. 1(a), an insulating substrate 1 on which a silicon single crystal layer 2, a silicon oxide film 3, and a silicon nitride film 1194 are sequentially formed is prepared. A photoresist layer 5 is formed and patterned, and a predetermined region 4a of the silicon nitride film 4 corresponding to the device molecule tiff STi region is removed by etching using the remaining portion of the photoresist N5 as a mask. Note that the process shown in FIG. 1(a) is similar to that shown in FIG. 2(a) in the conventional example.
The steps are the same as those shown in a) and (b).

Next, as shown in FIG. 1(b), the remaining portion of the photoresist layer 5 is used as a mask to irradiate the energy beam B, that is, ion implantation of silicon, oxygen, etc. is performed to form a predetermined portion of the silicon nitride film 4. A predetermined region 2a of the silicon single crystal layer 2 that will become an element isolation region is made amorphous through a predetermined region 3a of the silicon oxide film 3 exposed under the region 4a. At this time, in order to polycrystallize the predetermined region 2a of the silicon single crystal layer 2, the region 2a is once made amorphous, the photoresist layer 5 is removed, and the region 2a is heated at a temperature of about 6.00°C. It may be annealed.

Subsequently, as shown in FIG. 1(c), all remaining portions of the photoresist layer 5 are removed, and this complete I! By heat-treating the substrate 1 in a gas atmosphere containing oxygen,
A polycrystalline or amorphous predetermined region 2a of silicon single crystal layer 2 located under a predetermined region 4a of silicon nitride film 4 is oxidized.

At this time, since the polycrystalline or amorphous predetermined region 2a of the silicon single crystal layer 2 has a higher compound generation rate than other single crystal regions, the oxidation reaction occurs along the thickness direction. In this case, the bird's peak travels faster than in the lateral direction, and the occurrence of bird's peak can be effectively suppressed.

As a result, the predetermined region 3a of the silicon oxide film 3 is expanded along its thickness direction, and an element isolation region 6 made of silicon oxide, that is, an insulator, is formed with a required thickness as shown in FIG. 1(d). As a result, element formation regions 2b, 2b in silicon single crystal layer 2 are separated from each other.

(Effects of the Invention) As explained above, according to the method of manufacturing a semiconductor device according to the present invention, a predetermined region of a silicon single crystal layer that will become an element isolation region is made polycrystalline or amorphous by irradiation with an energy beam. After that, the polycrystalline or amorphous region of the silicon single crystal layer is oxidized by heat treatment in an oxygen-containing gas atmosphere.

Therefore, the polycrystalline or amorphous region in this silicon single crystal layer has a higher compound generation rate than other single crystal regions covered with the remaining silicon nitride film. , the occurrence of bird's peaks is effectively suppressed. Therefore, it is possible to expand the element formation area, and as a result, it is possible to achieve the effect of enabling high integration in the semiconductor device.

[Brief explanation of drawings]

FIGS. 1(a) to (d) are process cross-sectional views showing the method for manufacturing a semiconductor device according to the present invention, and FIGS. 2(a) to (d)
1 is a process cross-sectional view showing a conventional manufacturing method. In the figure, numeral 1 is an insulating substrate, 2 is a silicon single crystal layer,
2a is the predetermined region, 3 is the silicon oxide film, 3a is the predetermined region (exposed region), 4 is the silicon nitride film, 4a is the predetermined region, 5 is the photoresist layer, 6 is the element isolation region, and B is the energy beam. It is. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] (1) Prepare an insulating substrate on which a silicon single crystal layer, a silicon oxide film, and a silicon nitride film are sequentially formed, and then form a photoresist layer on the silicon nitride film and pattern it. using the remaining portion of the photoresist layer as a mask to remove a predetermined region of the silicon nitride film corresponding to the element isolation region; and irradiating an energy beam using the remaining portion of the photoresist layer as a mask to penetrate the exposed region of the silicon oxide film. a step of polycrystalizing or amorphizing a predetermined region of the silicon single crystal layer that will become an element isolation region; and after removing the remaining portion of the photoresist layer, heat treatment is performed in an oxygen-containing gas atmosphere. A method for manufacturing a semiconductor device, comprising the step of oxidizing a polycrystalline or amorphous region of the silicon single crystal layer to form an element isolation region.