JPS62254444A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To contrive improvement in isolation characteristics by a method wherein the first insulating film is formed on the part which is wider than the isolated region on the surface of a substrate, an epitaxial layer is formed on the whole surface of the substrate, the second insulating film is formed on the aperture part of the epitaxial layer of the isolated region, and the isolated region is formed with both insulating films. CONSTITUTION:A thermally oxided silicon film is grown on a substrate 1, the part which will be turned to an isolated region is left by etching, and two films 2 are formed. Then, a single crystal layer 6 of the same conductivity type as that of the substrate 1 is formed on the substrate 1 by an epitaxial growth method. Subsequently, an aperture having the width narrower than the width of the film 2 is perforated on the single crystal layer 6, a mask 7 is provided on all the parts excluding the aperture part, and the single crystal layer 6 is removed as deep as to the film 2 by performing etching. Then, after the mask has been removed, a film 8 is grown on the surface of the single crystal layer 6. Subsequently, a film 9 is coated, and the film 9 other than the film 10 which is filled in the aperture is removed by etching. Then, a film 11 is formed on the film 10, and the film 8 on the single crystal layer 6 is removed by etching until the surface of the single crystal layer 6 is exposed. As a result, the microscopic isolation of a deep region can be performed when the isolated region is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for manufacturing a semiconductor device, and particularly to a method suitable for forming isolation regions in a semiconductor integrated circuit.

(Prior Art) Various techniques have been proposed as methods for forming isolation regions in semiconductor integrated circuit manufacturing, such as selective oxidation, junction isolation, trench isolation, selective epitaxial growth, and insulating film embedding. There is, though.

The only methods that have been put into practical use are the selective oxidation method and the junction isolation method.

(Problems to be Solved by the Invention) However, with the selective oxidation method, it is very difficult to isolate deep regions, for example, the well region of a complementary MO8 field effect transistor, and other design measures must be taken. Furthermore, the above-mentioned junction separation method cannot be miniaturized. Furthermore, in the trench isolation method, in which a trench is simply formed in a semiconductor substrate and an insulating film is formed inside the trench, it is extremely difficult to form a channel stop region at the bottom of the trench.
It is necessary to form a groove of ~6p11. In addition, the selective epitaxial growth method described above, in which an insulating film serving as an isolation region is formed in advance and an epitaxial layer is grown only in the element region, has not been put to practical use because facets and crystal defects occur during epitaxial growth. ,
There is also the insulating film embedding method, which involves forming an inclined groove with a depth of about 1 μm in a semiconductor substrate, and forming an insulating film inside the groove.

As with the selective oxidation method, separation in deep regions is enhanced.

As described above, the conventional technology has a problem in that it is very difficult to separate deep regions that are accompanied by miniaturization.

The present invention provides a method for manufacturing a semiconductor device that allows deep isolation in forming isolation regions.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides a method of first insulating a portion of a semiconductor substrate surface that will be an isolation region in advance in an area equal to or wider than this area. A film is formed in advance, and an epitaxial layer is formed on the entire surface of the semiconductor substrate by performing epitaxial growth from the surface of the semiconductor substrate and epitaxial growth in a lateral direction on the first insulating film, and forming a portion that will become the isolation region. A hole is opened in the epitaxial layer, a second insulating film is formed in the opening, and an isolation region is formed by this insulating film and the first insulating film.

Therefore, the generation of crystal defects observed in the selective epitaxial growth method is limited to the bottom end of the isolation region, and the single isolation characteristics are greatly improved.

In addition, if the same type of impurity as the well is diffused into the well formation region in advance to a concentration of about one order of magnitude higher than the well concentration, and the well is diffused after separation, the same characteristics as the junction separation method can be obtained in fine patterns. Become.

(Function) According to the manufacturing method of the present invention, most of the crystal defect layer at the insulating interface caused by epitaxial growth can be removed, and furthermore, well separation can be achieved using a fine pattern. Furthermore, due to the presence of an underlying insulating film,
It becomes possible to form isolation regions of uniform depth, and non-uniformity in the depth direction, which has conventionally been a problem when forming trenches, is also eliminated.

(Example) One example and other examples of the present invention will be described with reference to FIGS. 1 and 2.

1 and 2 are cross-sectional views showing steps of one embodiment and another embodiment of the method for manufacturing a semiconductor device according to the present invention, and FIGS. 1(a) to 1(i) and Figures 2(a) to 2(Q) show the order of these steps.

In FIGS. 1 and 2, 1 is an N-type silicon substrate, 2
, 8.11 is a silicon oxide film, 3.12 is an implantation mask,
4 and 13 are boron ions, 5 and 14 are P-type diffusion layers, 6 is a silicon single crystal layer, 7 is an etching mask, and 9. IQ is a polysilicon film, and 15 is a pitaxial layer to be separated.

In FIG. 1(a), a thermally oxidized silicon crotch is grown to a thickness of 300 nm on an N-type silicon substrate 1, and only the portion that will become the isolation region is left by etching, forming two silicon oxide films 2 with a distance of lOμ9 and a width of 2μ. In FIG. 1(b), the primary insulating film is heated at 850°C on the N-type silicon substrate 1.
A silicon single crystal layer 6 having a thickness of 3p and having the same conductivity type as the N-type silicon substrate 1 was formed by epitaxial growth at a low temperature and pressure of 30 Torr.

At this time, due to the horizontal epitaxial growth of the silicon single crystal layer 6 on the silicon oxide film 2, a depression was formed in the silicon single crystal layer 6 above the silicon oxide film 2. Next, in FIG. 1(c), in order to form an isolation region, a layer of 1.6 mm narrower than the width of the silicon oxide film 2 is formed on the silicon single crystal layer 6.
An opening of μ is made, an etching mask 7 is applied to the other parts, and the silicon single crystal layer 6 is reached to the silicon oxide film 2 by one-reactive ion etching as shown in FIG. It was removed by anisotropic etching. Next, in FIG. 1(e), after removing the etching mask 7, a 20° n11 silicon oxide film 8 was grown on the surface of the silicon single crystal layer 6 to form a part of the second insulating film.

Next, in FIG. 1(f), a polysilicon film 9 is deposited to fill the opening, and as shown in FIG. 1(g), other than the polysilicon film 10 filled in the opening. After removing the polysilicon film 9 by etching, the polysilicon film 9 shown in FIG.
In h), a silicon oxide film 11 with a thickness of 400 nm was formed on the polysilicon film 10 by thermal oxidation, but the increase in the thickness of the silicon oxide film 8 at this time was less than 50 nm.

Further, as shown in FIG. 1(i), a silicon single crystal layer 6
The upper silicon oxide wX8 was removed by etching until the surface of the silicon single crystal layer 6 was exposed. In this way, the silicon oxide films 8 and 11 and the polysilicon film 10 are combined to form a second insulating film, and an isolation region is formed by this second insulating film and the first insulating film, and these two The region 15 of the epitaxial layer sandwiched between the isolation regions will be separated from the remaining regions of the epitaxial layer.

Next, another embodiment of the present invention will be explained with reference to FIG.

In FIG. 2(a), a thermally oxidized silicon film is grown to a thickness of 300 nm on an N-type silicon substrate 1, and only the portion that will become one isolation region is left by etching to form two silicon oxide films 2 with an interval of 10 μ9 and a width of 2 μ. This was used as the first insulating film. Next, in FIG. 2(b), regions other than the P-type well region formed on the N-type silicon substrate 1 were covered with an implantation mask 3, and boron ions were implanted to form an implantation layer 4. In FIG. 2(c), the injection layer 4 is subjected to a known annealing process to convert it into a P-type diffusion layer 5, and then is placed on an N-type silicon substrate 1 at 850° C. for 30T.
Thickness 3 by low-temperature, low-pressure epitaxial growth
A silicon single crystal layer 6 of p11 was formed. At this time, due to the horizontal epitaxial growth of the silicon single crystal layer 6 on the silicon oxide film 2, on the upper part of the silicon oxide film 2,
A depression was formed in the silicon single crystal layer 6.

Next, in FIG. 2(d), in order to form an isolation region, a layer narrower than the width of the silicon oxide film 2 is placed on the silicon single crystal layer 6.
．． An opening of 6 μm is made, an etching mask 7 is applied to the other parts, and the silicon single crystal layer 6 is reached to the silicon oxide film 2 by one-reactive ion etching as shown in FIG. 2(e). In FIG. 2(f), after removing the etching mask 7, a silicon oxide film 8 with a thickness of 200 nm is grown on the surface of the silicon single crystal layer 6. In FIG. 2(g), a polysilicon film 9 is deposited to fill the opening, and as shown in FIG. 2(h), the opening is filled with polysilicon film 9. The polysilicon film 9 other than the polysilicon film 10 filled in was removed by etching.

Next, in FIG. 2(i), a film with a thickness of 4
A silicon oxide film 11 with a thickness of 00 nm was formed by thermal oxidation, but the increase in the thickness of the silicon oxide film 8 at this time was 50 nm or less. Furthermore, as shown in FIG. 2(j), the silicon oxide film 8 on the silicon single crystal layer 6 was etched and removed until the surface of the silicon single crystal layer 6 was exposed. In this way, the silicon oxide films 8 and 11 and the polysilicon @io were combined to form a second insulating film, and an isolation region was formed by this second insulating film and the first insulating film.

Next, as shown in FIG. 2(k), in order to form a P-type well in the region between the isolation regions, an implantation mask 12 is applied to the surfaces of the silicon single crystal layer 6 and the silicon oxide film 11 excluding the isolation regions. After coating, boron ions were implanted to form an implanted layer 13. Finally, as shown in FIG. 2 (12), after removing the implantation mask 12, a P-type diffusion layer 14 was formed by an annealing process and a diffusion process.

Note that in the other embodiments of the present invention, only the case of forming a P-type well has been described, but the present invention is similar to the above.

It goes without saying that it can also be used in the case of an N-type well or a double-well structure.

(Effects of the Invention) As described above, according to the method of manufacturing a semiconductor device of the present invention, it is possible to isolate a deep region with miniaturization in the formation of an isolation region, and therefore, it is possible to significantly increase the density of integrated circuits. have an effect.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing steps in one embodiment of the method for manufacturing a semiconductor device of the present invention, and FIG. 2 is a sectional view showing steps in another embodiment. 1... N-type silicon substrate, 2, 8.11... Silicon oxide film, 3.12... Injection mask, 4.13...
Boron ion implantation layer, 5, 14...P type diffusion layer, 6
...Silicon single crystal layer, 7...Etching mask,
9.10...Polysilicon film, 15...Epitaxial layer to be separated. Patent applicant Matsushita Electronics Co., Ltd. Figure 1 Figure 1 Figure 1 Figure 2 Figure 4... Boron 4-off body interlocking Figure 2 Figure 2

Claims (2)

[Claims] (1) A first step of forming two first insulating films having a predetermined interval and width on the surface of a semiconductor substrate of one conductivity type, and epitaxial growth from the surface of the semiconductor substrate other than the first insulating film. and a second step of forming an epitaxial layer of the same conductivity type as the semiconductor substrate on the entire surface of the semiconductor substrate by performing lateral epitaxial growth on the first insulating film; a third step of removing the epitaxial layer in a region equal to or narrower than the first insulating film width by etching to open a hole; and a second step of forming a second insulating film in the opening by a known method. By comprising the step 4, the second insulating film having the predetermined interval formed by the first insulating film and the second insulating film is formed.
1. A method of manufacturing a semiconductor device, comprising: forming two isolation regions, and separating the epitaxial layer between the two isolation regions from the remaining epitaxial layer. (2) A first step of forming two first insulating films having a predetermined interval and width on the surface of a semiconductor substrate of one conductivity type, and forming a gap between the two first insulating films on the semiconductor substrate. a second step of forming a diffusion layer of a conductivity type opposite to that of the semiconductor substrate in a region, epitaxial growth from the surface of the semiconductor substrate other than the first insulating film, and lateral growth on the first insulating film a third step of forming an epitaxial layer of the same conductivity type as the semiconductor substrate on the entire surface of the semiconductor substrate by performing epitaxial growth; and a third step of forming an epitaxial layer of the same conductivity type as the semiconductor substrate on the entire surface of the semiconductor substrate, and a width equal to or narrower than the width of the first insulating film on the first insulating film. a fourth step of removing the epitaxial layer in the region by etching to open a hole; a fifth step of forming a second insulating film in the opening by a known method; By comprising a sixth step of forming a diffusion layer of a conductivity type opposite to that of the semiconductor substrate in the epitaxial layer between the two isolation regions having the predetermined interval and consisting of a second insulating film, a complementary type A method for manufacturing a semiconductor device, comprising separating a well region of a MOS transistor from the remaining epitaxial region.