JPS6358921A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To form semiconductor region having a high concentration in to eliminate a leakage current by containing an interface, and one conductivity type impurity in an insulating film around a recess region so as to diffuse the impurity at the edge of a semiconductor layer before selective growth of the layer is carried out. CONSTITUTION:SiO2 film parts 2 are formed to make a recess region 3, a polycrystalline silicon film 10 is grown thereon to form an SiO2 film 10', and vertically etched by RIE method to allow the film 10' to remain only on the surfaces the region 3. Then, an n-type silicon layer 4 is selectively grown by epitaxial growth, with reaction gas in which phosphine is added to trichlorosilane (SiHCl3) of main ingredient, and the recess region is filled by the growth to flatten the surface. Phosphorus is diffused from the film 10' at the time of growth, and an n<+> type silicon regions 41 are formed on the side surfaces in contact with the film 10'. Thus, since the regions 41 of high concentration are formed on the side surfaces of insulating film element separating bands, the production of an inverted layer due to a crystal defect is suppressed, and the generation of a leakage current is also suppressed.

Description

[Detailed Description of the Invention] Summary] A formation method in which a semiconductor layer for forming an element is selectively grown in a recessed region on a semiconductor substrate after an insulating film element isolation band is formed in advance. During selective growth, impurities of one conductivity type are contained in the insulating film around the recessed region or the entire surface of the insulating film in advance so that the -conductivity type impurities are diffused around the semiconductor layer. This eliminates leakage current at the sidewall interface of the device isolation band, improving the quality of the semiconductor device.

[Industrial Application Field] The present invention relates to a method for manufacturing a semiconductor device, and particularly relates to an improvement in a manufacturing method in which a semiconductor layer is selectively grown epitaxially between insulating separation bands and an element is formed in the semiconductor layer. .

In semiconductor devices such as ICs and LSIs, a large number of semiconductor elements (cells) are provided on a semiconductor substrate, and element isolation bands are formed to electrically isolate these semiconductor elements. It is desirable to form the element isolation band as precisely and finely as possible. Therefore, various manufacturing methods have been proposed in which fine isolation bands are provided, but sufficient attention must be paid to improving the quality of semiconductor devices having such structures.

[Prior Art] Conventionally, I
OP (Isolation of Polysil)
The IC-? 'As a formation method for achieving high integration of LSI, an insulating film is formed on a semiconductor substrate,
A manufacturing method has been devised in which the insulating film is patterned to remove the insulating film in the element region to form a recessed region, and a semiconductor layer is selectively epitaxially grown in the recessed region to form an element in the semiconductor layer. There is.

Figures 3(a)-(
To explain the outline of the process, first, as shown in ta+ in the same figure, a silicon oxide (SiO2) film 2 as an element isolation band is deposited on a p-type silicon substrate 1,
The concave region 3 is formed by patterning using lithography technology. Next, as shown in the same figure ('b), n
Type 9937 layer 4 is selectively epitaxially grown. Thereafter, as shown in FIG. 4C, an MO3 semi-conducting semiconductor 5 is formed on the n-type 9937 layer 4 by a known manufacturing method.

Figures 4 (al and bl) show diagrams for explaining the thus formed semiconductor device and its problems; )'s AA'
Side A is fal in the same figure. In the figure, 1 is a p-type silicon substrate, and 2 is an insulating film element isolation band made of a 5i02 film.

4 is an n-type silicon layer, 51 is a p-type source region and drain region, 52 is a gate insulating film, and 53 is a gate electrode.

That is, according to the present manufacturing method, the device isolation band 2 can be formed finely, and the n-type 9937 layer 4 for forming the device can be formed finely.
The structure is similar to the LOCO8 method, but the advantage is that it does not cause bird's beaks and the separation band width can be miniaturized to about 1 μm. There is a certain method.

[Problems to be Solved by the Invention] By the way, in the above formation method, the SiO□ film 2 (insulating film separation band) is patterned by lithography technology to form the recessed region 3, and then an n-type film is formed in the recessed region. 9
When 937 layer 4 is selectively epitaxially grown, 5i02
Crystal defects occur in the n-type 9937 layer 4 at the interface with the film 2. This is because crystal defects are likely to occur on the surface in contact with the n-type 9937 layer 4 and the 5i02 film 2, and because of etching, impurities such as etching residues may be present on the side surfaces of the 5i02 film 2 (side surfaces of the recessed region). This is caused by the adhesion of
The n-type silicon layer is easily inverted to the p-type at the interface, forming an inversion layer.

Therefore, there is a drawback that a large amount of leakage current occurs in the semiconductor element placed on the n-type 9937 layer 4, which deteriorates the element characteristics. According to the experimental data, leakage current from the A side and the B side (width about 0.5 um) in FIG. 4 (bl) is particularly high.

The present invention proposes a method for manufacturing a semiconductor device that suppresses such problems and improves the quality of the semiconductor device.

[Means for Solving the Problem 1] The purpose is to form an insulating film on a semiconductor substrate and selectively remove the insulating film to form a recessed region in which the semiconductor substrate is exposed at the bottom; Next, a polycrystalline semiconductor film containing impurities of one conductivity type is deposited on the entire surface, and then the polycrystalline semiconductor film is thermally oxidized to transform it into an oxide semi-quaternary film. A method for manufacturing a semiconductor device, comprising the steps of etching the oxide semiconductor film anisotropically to leave the oxide semiconductor film only on the side surfaces of the recessed region, and then selectively epitaxially growing a semiconductor layer of one conductivity type in the recessed region. solved by.

Further, a step of forming an insulating film on a semiconductor substrate and incorporating an impurity of one conductivity type into the insulating film, then a step of selectively removing the insulating film to form a recessed region, and then a step of forming a recessed region in the recessed region. The problem can also be solved by a method of manufacturing a semiconductor device that includes a step of selectively epitaxially growing a semiconductor layer of one conductivity type.

[Operation] That is, in the present invention, before the semiconductor layer is selectively grown, the insulating film around the recessed region or the entire surface of the insulating film is injected in advance so that the -conductivity type impurity is diffused to the edge of the semiconductor layer. A conductivity type impurity is contained.

In this way, a highly concentrated semiconductor region (channel cut region) is formed at the interface. Therefore, leakage current at the side surfaces is eliminated, resulting in high quality.

[Example] Hereinafter, embodiments will be described in detail with reference to the drawings.

FIGS. 1(a) to 1(e) show step-by-step sectional views of the manufacturing method according to the present invention. First, as shown in the same figure (a), a p-type silicon substrate 1 is thermally oxidized at a high temperature of 1050 to 1100°C for several hundred minutes, and a SiO□ film 2 with a thickness of about 1 μm is formed.
and then 5i02 by lithography technique
The membrane 2 is patterned to form the recessed regions 3. Patterning of the 5i02 film 2 is performed by active ion etching (RIE) using carbon tetrafluoride (CF4) or trifluoromethane (CHF3) gas as a reactive gas using a resist film (not shown) as a mask.

Next, as shown in FIG. 1(b), a film with a thickness of 1,000 to 1,000 mm is formed on the top surface by low pressure chemical vapor deposition (low pressure CVD).
1,500 polycrystalline silicon films 10 are grown.

This CVD method uses monosilane (SiHa) and phosphine (PH3) as sources and thermally decomposes them at 700 to 750° C. to deposit a polycrystalline silicon film having a specific resistance of about 0.01Ω.

Next, as shown in FIG. 1(C), thermal oxidation treatment was performed at 950°C for several minutes to reduce the polycrystalline silicon film to a thickness of 2.
The 5i02 film 10' is transformed into a SiO2 film 10' having a thickness of 000 to 2500 A, and RIE is performed vertically to leave the 5i02 film 10' only on the side surfaces of the recessed region 3.

Next, as shown in FIG. 1(d), thermal decomposition was performed at a temperature of 950 to 1000° C. for about 30 minutes using a reaction gas containing trichlorosilane (Si HCl3) as the main component and phosphine added to give n. A type 9937 layer 4 is selectively grown epitaxially to fill the recessed regions and flatten the surface. During this growth, phosphorus diffuses from the 5i02 film 101 into the n-type 9937 layer 4, and an n"-type silicon region 41 is formed on the side surface in contact with the SiO2 film 10". but,
In this case, when the temperature for diffusion of phosphorus is insufficient for 1 hour, the high temperature (950-1000℃) in nitrogen gas is added.
You may add heat treatment for 40 to 60 minutes.

Next, as shown in FIG. 1(e), n
A MOS semiconductor element 5 is formed on the mold 9937 layer 4.

If such a formation method is adopted, a highly concentrated region 41 (channel cut region) is formed on the side surface of the insulating film element isolation band, which prevents the formation of an inversion layer due to crystal defects and, in turn, the generation of leakage current. As a result, the device characteristics of the MOS semiconductor device 5 are stabilized, and the quality of the IC can be improved.

In addition, FIGS. 2(a) to (C1) show step-by-step sectional views of another manufacturing method according to the present invention, and in this example, first, as shown in the same figure (al), a p-type silicon substrate 1 is 1050～
Thermal oxidation is performed at a high temperature of 1100℃ for several hundred minutes, resulting in a film thickness of 1μm.
A 5i02 film 2 of about 100% is produced, and phosphorus (or arsenic) ions are implanted into the 5i02 film 2 by an ion implantation method.

Next, as shown in FIG.
form. The patterning of this 5i02 film 2 is carried out in the same manner as the step shown in FIG. 1(a) in the above example.

Next, as shown in FIG. 2(C), an n-type 9937 layer 4 is formed.
selective epitaxial growth to fill the recessed regions. During this growth, phosphorus is transferred from the 5i02 film 2 to n-type 99
37 layer 4, and an n+ type silicon region 41 is formed on the side surface in contact with the 5i02 film 2.

Although the details of the explanation are omitted, this step is also the same as the first step in the above example.
This process is similar to the process shown in Figure (d).

Next, although not shown, the MO3 semiconductor element 5 is formed on the n-type 9937 layer 4 by a known manufacturing method, similar to FIG. 1(e).

Also by such a formation method, a high concentration region 41 (channel cut region) is formed on the side surface of the insulating film element isolation band. Moreover, in the manufacturing method shown in FIG. 2, 5i02
Instead of ion-implanting phosphorus into the film 2, a method may also be considered in which phosphorus is implanted into the surface of the silicon substrate 1 in advance and phosphorus is contained in the 5i02 film 2 during thermal oxidation of the 5i02 film.

Incidentally, the manufacturing method explained in FIG. 2 has the advantage of simplifying the process.

[Effects of the Invention] As is clear from the above description, according to the present invention, a channel cut region is formed on the side surface of the insulating film element isolation band,
Leakage current at the insulating film interface is reduced, and the quality of the IC can be improved.

[Brief explanation of drawings]

1(a) to (e) are step-by-step cross-sectional views of a manufacturing method according to the present invention, FIG. 2 ta) to (C) are step-by-step cross-sectional views of another manufacturing method according to the present invention, and FIG. (a) to (C) are step-by-step cross-sectional views of a conventional manufacturing method, and FIG. 4(b) is a diagram illustrating the problems of the conventional method. In the figure, l is a p-type silicon region, 2 is a 5i02 film (insulating film element isolation band), 3 is a recessed region, 4 is an n-type silicon layer, 5 is an MO3 semiconductor element, 10 is a polycrystalline silicon film, and 10' is a 5i02 film, 41 indicates the n" type silicon region. 3E! Cultivate JiP4'. Figure 1 5 MOS view) Illustrated drawing Figure 1 Figure 3 Recessed part 4 wrinkle layers, / mun kepi 3'ly + hiru F11 gu danjun m Figure 3

Claims (2)

[Claims] (1) forming an insulating film on a semiconductor substrate and selectively removing the insulating film to form a recessed region in which the semiconductor substrate is exposed at the bottom; Depositing a crystalline semiconductor film, and then thermally oxidizing the polycrystalline semiconductor film to transform it into an oxide semiconductor film; Next, vertically anisotropically etching the oxide semiconductor film to remove side surfaces of the recessed region. A method for manufacturing a semiconductor device, comprising: a step of leaving the oxide semiconductor film only in the recessed region; and a step of selectively epitaxially growing a semiconductor layer of one conductivity type in the recessed region. (2) a step of forming an insulating film on a semiconductor substrate and incorporating an impurity of one conductivity type into the insulating film; then, a step of selectively removing the insulating film to form a recessed region; then, a step of forming a recessed region; 1. A method of manufacturing a semiconductor device, comprising the step of selectively epitaxially growing a semiconductor layer of one conductivity type.