JPS63174309A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To prevent the generation of a bird's beak by forming a recessed groove in an element forming region on the surface of an insulating film deposited on a substrate and by forming the single crystal semiconductor element forming region deposited on the insulating film thicker than the other region. CONSTITUTION:After an SiO2 film 12 on which a groove 13 is formed is formed on a single crystal Si substrate 11 and a polycrystalline Si film 14 is formed on the SiO2 film 12, the film 14 is melted by irradiating an electron beam and recrystallized and a single crystal Si film 14' is formed. In this case, the Si film near an element forming region flows over the groove 13 and the thickness of the film 14' in the element forming region is made thicker. Then, an Si3N4 film 17 is formed in the element forming region and a field oxide film 18 is formed by oxidizing the film 14' using the film 17 as a mask. In this case, a bird's beak is not extended to the element forming region since the thickness of the single crystal Si film except the element forming region where the film 18 is to be formed is thinner. Then, the film 17 is removed and a gate oxide film 19, a gate electrode 20, a source region 21, a drain region 22, an Al wiring 24, etc., are formed.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Field of Application) The present invention relates to a method of manufacturing a semiconductor device, and particularly relates to a method for manufacturing a semiconductor device, and in particular, a method for manufacturing a device three-dimensionally by forming a single crystal semiconductor film on an insulating film. The present invention relates to a method for manufacturing stacked semiconductor devices.

(Prior art) In recent years, elements have become increasingly finer due to the higher integration and density of semiconductor devices, but there is a limit to the miniaturization of elements, and it is difficult to arrange elements two-dimensionally. Improvements in the degree of integration are nearing their limits.

Therefore, recently, a so-called three-dimensional IC has been proposed in which elements are stacked three-dimensionally by forming elements not only on a substrate but also on an insulating film.

To manufacture a three-dimensional IC, it is necessary to form a single crystal semiconductor film on an insulating film deposited on a silicon substrate. For this reason, a polycrystalline or amorphous semiconductor film is deposited on an insulating film deposited on a silicon substrate, and the semiconductor film is made into a single crystal by irradiation with a laser beam or an electron beam (beam annealing).

By forming an element on this single crystal film, a two-layer structure is realized in which a lower layer element formed on the substrate and an upper layer element formed on the single crystal film are laminated with an insulating film interposed therebetween. Furthermore, a three-layer structure is realized by forming a single crystal film on the upper layer element via an insulating film and forming the element on this single crystal film.

However, this type of method has the following problems. That is, an element is formed on a single crystal film (1).

In particular, when device isolation is performed by thermal oxidation, the thermal oxidation time must be increased as the single crystal film thickness increases, and oxidation invasion into the device region called bird's beak makes it difficult to form short channel devices. Met. Furthermore, if a single crystal semiconductor film is made thinner for the purpose of facilitating element isolation, the electrical breakdown voltage of the semiconductor element decreases as the semiconductor film becomes thinner, making it difficult to obtain good element characteristics.

Incidentally, the occurrence of the bird's beak will be explained with reference to FIG. 2. After forming a single-crystal silicon film 34 on an insulating film 32 on a silicon substrate 31, a silicon nitride film 37 is formed only on the element formation region, and in this state a heat treatment for element isolation is performed.

At this time, the silicon film is oxidized to become a silicon oxide film 38 in the areas where the silicon nitride film 37 is not present.

Furthermore, the oxidizing agent penetrates into the lower part of the silicon nitride film 37 from the edge of the silicon nitride film 37, and oxidation progresses in the lower part of the silicon nitride film 37, resulting in the formation of bird's beaks 39 there.

(Problems to be Solved by the Invention) In this way, in the conventional method, when forming a semiconductor element on a single crystal semiconductor film on an insulating film, it is necessary to increase the thermal oxidation time for element isolation as the semiconductor film becomes thicker. However, as a result, the number of bird's beaks increases, making it difficult to form a short channel element. Further, when the single crystal film is made thinner in order to reduce bird's beak, there is a problem in that in a field effect type conductor element, the withstand voltage between the source and drain decreases, and the element characteristics deteriorate.

The present invention has been made in consideration of the above circumstances, and its purpose is to increase the thickness of the single crystal film in the element region to sufficiently increase the withstand voltage between the source and drain, and to improve the device isolation process. It is an object of the present invention to provide a method for manufacturing a semiconductor device that can reduce bird's beak caused by , and is suitable for manufacturing a three-dimensional IC.

[Structure of the Invention] (Means for Solving the Problems) The gist of the present invention is to form a single crystal semiconductor film thickly in the element formation region and to reduce the thickness of the single crystal semiconductor film in the element isolation region. It is about forming.

That is, the present invention provides a method for manufacturing a semiconductor device in which a semiconductor element is formed on an insulating film deposited on a semiconductor substrate, in which a concave shape is formed on the surface of the insulating film corresponding to a region on the insulating film that is to become an element region. After forming the groove, a polycrystalline or amorphous semiconductor film is deposited on the insulating film, and then the semiconductor film is made into a single crystal by a beam annealing method, and then a desired element is formed in the single crystal semiconductor film. This is a method that allows the formation of

(Function) Since the semiconductor film is melted in a liquid state during beam annealing, the semiconductor film outside the concave groove flows into the inside of the groove, and the thickness of the semiconductor film inside the groove is increased more than outside the groove. Therefore, the semiconductor film deposited on the entire surface of the insulating film before beam annealing becomes thicker only in the region that is to become the element region after beam annealing.

From this, it is possible to make the semiconductor film thickness of the trench portion in which the field effect semiconductor element is formed to be thick enough to prevent a decrease in breakdown voltage between the source and drain. On the other hand, since the thickness of the semiconductor film in the region outside the trench to be oxidized in the element isolation step becomes thinner, the increase in bird's beak is prevented as the thermal oxidation time is shortened, and a short channel field effect semiconductor element can be formed.

(Example) Hereinafter, details of the present invention will be explained with reference to illustrated embodiments.

FIG. 1 is a cross-sectional view showing the manufacturing process of a semiconductor device according to an embodiment of the present invention. First, as shown in FIG. 1(a), a resist pattern (not shown) is formed on a single crystal Si substrate 11 on which a desired element is formed by sputtering or CVD in a portion that is to become an i pre-separation region. Using this resist pattern as a mask, the 5i02 film 12 is etched by RIE or the like.
A groove 13 with a depth of 5000 mm is formed on the surface of the 02 film 12. Next, as shown in FIG. 1(b), a polycrystalline Si film (semiconductor film) 14 is deposited over the entire surface to a thickness of aooo [man].

Next, as shown in FIG. 1(c), the polycrystalline Si film 1 is irradiated with an electron beam 15 and scanned in one direction.
4 is melted and recrystallized to form a single crystal Si film 14'.

At this time, the Si film near the element formation region flowed onto the groove 13, and the thickness of the single crystal Si film 14' in the element formation region became 5000 mm thick. Furthermore, the thickness of the single crystal Si film 14' near the element formation region was reduced to 1500 [layers]. Note that the acceleration voltage of the electron beam 15 is 12 [ke
V], and the beam current was 2 [mA].

Next, as shown in FIG. 1(d), a single crystal SL film 1'
A 5i3Na film 17 is deposited on top to a thickness of 2000 μm, and a Si3N4 film 17 is deposited only on the element formation region using a resist pattern (not shown) as a mask, and the remaining i4' is oxidized.
As shown in figure (e), fee +6. , a V resist 1 curve is formed. At this time, since the thickness of the single crystal Si film other than the element formation region where the field oxide film 18 is to be formed was sufficiently thin, the bird's beak hardly extended into the element formation region.

Next, as shown in FIG. 1(f), the 5t31'Ja film 1
After removing the gate oxide film 19 with a phosphoric acid solution at 180[°C], the gate oxide film 19 is heated to a temperature of 400[°C] by thermal oxidation in an oxygen atmosphere.
form to the thickness of a person]. Then a normal N-channel MO
Similarly to the S transistor manufacturing process, as shown in FIG.
, and further 5i02 film 23 and A, ff wiring 24
form.

As a result, a three-dimensional IC in which elements are three-dimensionally stacked is realized.

Thus, according to the method of this embodiment, even though the polycrystalline Si film 14 before beam annealing is as thin as 3,000 [people],
The MOS transistor forming region of the single crystal Si film 14' after beam annealing is as thick as 5000 [people].

Therefore, source-drain breakdown voltage failure does not occur, and good device characteristics can be obtained. Furthermore, it becomes possible to significantly reduce the damage after beam annealing. Therefore, it is possible to form a short channel device with good device characteristics, which is extremely effective in manufacturing three-dimensional ICs and the like.

Note that the present invention is not limited to the method of the embodiment described above. For example, as a means for annealing the semiconductor film on the insulating film, laser annealing using a laser beam instead of an electron beam may be performed. Further, the semiconductor film is not limited to polycrystalline Si, but may be amorphous St, and other semiconductor materials may also be used.

In addition, the semiconductor element formed on the single crystal semiconductor film is MOS)
The present invention is not limited to transistors, and can be applied to various semiconductor devices. Further, the thickness of the insulating film, the etching method, the oxidation method of the single crystal semiconductor film, etc. can be changed as appropriate depending on the specifications. In addition, various modifications can be made without departing from the gist of the present invention.

[Effects of the Invention] As described in detail above, according to the present invention, the single crystal film thickness in the element region can be increased, which is extremely effective in manufacturing an IC between a source and a drain.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the manufacturing process of a semiconductor device according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view for explaining the problems of the conventional method. 11...Si substrate, 12...5i02 film (insulating film)
, 13... Concave groove, 14... Polycrystalline Si film (semiconductor film), 14'... Single crystal Si film, 15... Electron beam, 17... 5i3Ni film, 18... Field Oxide film, 19... Gate oxide film, 20... Gate electrode, 21.22... Source/drain region. Applicant: Director of the Agency of Industrial Science and Technology Kozo Iizuka Figure 1

Claims (2)

[Claims] (1) In a method of manufacturing a semiconductor device in which a semiconductor element is formed on an insulating film deposited on a semiconductor substrate, a concave groove is formed in the surface of the insulating film corresponding to a region on the insulating film that is to become an element region. a step of depositing a polycrystalline or amorphous semiconductor film on the insulating film; a step of making the semiconductor film into a single crystal by a beam annealing method; 1. A method for manufacturing a semiconductor device, comprising the step of forming an element. (2) The semiconductor film according to claim 1, wherein the single crystallized semiconductor film has a film thickness inside the concave groove that is thicker than the film outside the groove compared to before the single crystallization. Method of manufacturing the device. (3) The first aspect of the present invention is characterized in that the beam annealing method uses an electron beam or a laser beam and scans the beam on the semiconductor film.
A method for manufacturing a semiconductor device according to section 1.