JPH0793265B2 - Method for manufacturing semiconductor crystal layer - Google Patents

Description

The present invention relates to a technique for forming a semiconductor single crystal layer on an insulating film, and particularly to the production of a semiconductor crystal layer using a beam annealing method. Regarding the method.

(Prior Art) Conventionally, in order to form a semiconductor single crystal layer on an insulating film,
The method shown is used. In this method, as shown in FIG. 6 (a), a silicon convex portion is formed on the surface of the silicon substrate 61.
62 is formed, and the area other than the convex portion 62 is filled with the CVD oxide film 63. Next, a polycrystalline silicon film 64 is deposited on the entire surface and CVD is performed.
A cap layer 65 formed of an oxide film is further deposited. Then, by irradiating an energy beam 66 such as a laser beam or an electron beam, the convex portion 62 called a seed is formed.
Part of the polycrystalline silicon film 64 is once melted by using the surface of the as a seed of crystal orientation. At this time, heat flows out to the silicon substrate 61 from the surface of the seed portion having high heat conductivity. Then, the polycrystalline silicon film 63 becomes a single crystal layer by melting and recrystallization.

However, this type of method has the following problems. That is, as shown in FIG. 6 (b), the silicon convex portion 62 has a continuous structure when viewed from above,
In this structure, when the polycrystalline silicon is melted on the surface of the seed portion by beam annealing, the amount of heat flowing out from the seed portion is large and it is necessary to increase the beam annealing power.
Therefore, the deformation of the silicon substrate 61 and the polycrystalline silicon film 63
Peeling off occurred, making it difficult to form an element on the semiconductor film.

(Problems to be solved by the invention) As described above, in the related art, since the heat often flows out from the seed portion,
There is no choice but to increase the power of beam annealing, which causes deformation of the substrate or peeling of the semiconductor thin film.

The present invention has been made in view of the above circumstances, and an object thereof is to reduce heat outflow from a seed portion, prevent substrate deformation, peeling of a semiconductor thin film, and the like, and Another object of the present invention is to provide a method for manufacturing a semiconductor crystal layer capable of forming a high quality single crystal layer.

[Structure of the Invention] (Means for Solving the Problems) The essence of the present invention is to reduce heat outflow through the seed portion by dividing the seed portion without making it continuous.

That is, the present invention, a convex portion is formed on the surface of the single crystal semiconductor substrate, an insulating film is embedded in the surface of the substrate other than the convex portion, and then a polycrystalline or amorphous semiconductor thin film is formed on the entire surface,
In the method of manufacturing a semiconductor crystal layer in which the semiconductor thin film is irradiated with an energy beam having a predetermined intensity distribution to melt and recrystallize the thin film, the protrusions are formed in a plurality of dots on the surface of a single crystal semiconductor substrate. And the arrangement of the point-shaped convex portions,
With respect to an energy beam having a predetermined intensity distribution, a region having high energy intensity is dense and a region having weak energy intensity is coarse.

(Operation) According to the present invention, the convex portions of the substrate are formed in a dot shape, and the arrangement of the dot-shaped convex portions is dense with respect to the energy beam having a predetermined intensity distribution, and the dense area is weak area. Since it is made coarse, it is possible to reduce the wasteful heat outflow through the seed portion and to make the temperature distribution of heat uniform over the entire substrate, which reduces the power of beam annealing. It becomes possible to form a better single crystal layer. Therefore, it becomes possible to prevent the deformation of the silicon substrate and the peeling of the semiconductor thin film, and to form a good quality semiconductor crystal layer on the insulating film.

(Examples) The details of the present invention will be described below with reference to illustrated examples.

1 and 2 are views showing a silicon single crystal layer manufacturing process. First, a plan view is shown in FIG. 1 and a first view is shown in FIG.
As shown in the sectional view taken along the line AA in the figure, a single crystal silicon substrate
A resist pattern (not shown) is formed in the seed region on 11 and the resist is used as a mask to etch the silicon substrate 11 to a depth of 1 μm by the reactive ion etching (RIE) method to form the silicon protrusions 12 Was formed. After that, the resist used as the mask was removed.

Then, as shown in FIG. 2 (b), the protrusions on the surface of the substrate 11
Silicon oxide film (SiO ₂ film) on areas other than 12 by CVD method 1
3 was embedded and formed. When burying the SiO ₂ film 13, a CVD-SiO ₂ film 13 is deposited to a thickness of 1 μm on the entire surface,
A resist (not shown) is applied thereon to flatten the surface. Then, the SiO ₂ film 13 on the silicon convex portion 12 may be removed by etching back by RIE under the condition that the etching rate ratio of the resist and SiO ₂ is substantially equal.

Then, as shown in FIG. 2 (c), a polycrystalline silicon film (semiconductor thin film) 14 on the entire surface is deposited to a thickness of 6000Å, and a CVD-SiO ₂ film (cap layer) 15 is further deposited to a thickness of 5000Å on it. It was piled up. After that, when the electron beam 16 was subjected to beam annealing of the sample under the conditions of an accelerating voltage of 12 KV and a beam current of 6 mA,
A single crystal film could be easily obtained without any deformation of the silicon substrate 11 and peeling of the polycrystalline silicon film.

Thus, according to the above method, since the silicon convex portion 12 serving as the seed portion is not continuous but has a divided structure, it is possible to reduce the heat outflow through the seed portion, and the electron beam It is possible to reduce energy. Therefore, a good-quality single crystal silicon layer can be formed on the SiO ₂ film 13 without causing substrate deformation or peeling of the thin film.

FIG. 3 is a process sectional view for explaining another method for manufacturing a silicon single crystal layer. The same parts as those in FIGS. 1 and 2 are designated by the same reference numerals, and detailed description thereof will be omitted.
This method is different from the method described above in the method of forming the convex portions of silicon.

In this method, first, as shown in FIG. 3 (a), a SiO ₂ film 17 having a thickness of 1000 Å is formed on a silicon substrate 11 by a hydrogen combustion oxidation method.
After forming, a silicon nitride film (Si ₃ N ₄ film) 18 having a thickness of 2500 Å was deposited by the low pressure CVD method. Subsequently, removing the resist pattern (not shown) is formed on the Si ₃ N ₄ film 18 on a region serving as the seed region the Si ₃ N ₄ film 18 other than the seed region using the resist as a mask by RIE did. In addition,
After this, the resist used as the mask was removed.

Then, the silicon substrate is subjected to hydrogen combustion oxidation at a temperature of 1000 ° C.
By selectively oxidizing 11, a SiO ₂ film 19 having a thickness of 1.4 μm was formed outside the seed region as shown in FIG. 3 (b).
This oxide film formation is similar to the well-known field oxide film formation process.

Then, the Si ₃ N ₄ film 18 was removed by the RIE method, and the SiO ₂ film 17 was further removed by an ammonia fluoride solution. In addition, outside the seed area
By removing the SiO ₂ film 19 with an ammonium fluoride solution, a convex portion 12 having a height of 7,000 Å was formed on the surface of the silicon substrate 11 as shown in FIG. 3 (c).

Then, as in the previous method, as shown in FIG. 3 (d), the SiO ₂ film 13 is embedded in the region other than the convex portion 12, and the entire surface is covered with a polycrystalline silicon film 14 having a thickness of 6000Å and a cap layer. The SiO ₂ film 15 was formed. In this state, when the electron beam 16 was subjected to beam annealing of the sample under the conditions of an accelerating voltage of 12 KV and a beam current of 6 mA, a good silicon single crystal layer could be formed as in the previous method.

Although the beam scanning direction is parallel to the seed arrangement in the above method, the beam scanning may be performed in the direction perpendicular to the seed arrangement as shown in FIG.

The present invention is an improvement of the method shown in FIGS. 1 to 4, in which the interval between the convex portions is changed in accordance with the beam intensity distribution as shown in FIG. That is, if the convex portions are roughened in a region where the beam intensity is high as in the present invention and the convex portions are dense in a region where the beam intensity is weak, a better single crystal layer can be formed.

The energy beam is not limited to the electron beam, and a laser beam, an ion beam, or the like can be used. Further, the film thickness of each layer, the etching method, the oxidation method, and the like can be appropriately changed according to the specifications. As the semiconductor thin film, amorphous silicon can be used instead of polycrystalline silicon, and a semiconductor other than silicon can also be used. In addition, various modifications can be made without departing from the scope of the present invention.

[Effects of the Invention] As described in detail above, according to the present invention, the convex portions on the surface of the substrate are formed in a dot shape, and the arrangement of the dot-shaped convex portions is different from that of an energy beam having a predetermined intensity distribution. The strong areas are dense and the weak areas are coarse.
It is possible to reduce unnecessary heat outflow through the seed portion and to make the temperature distribution of heat uniform over the substrate as a whole, which prevents substrate deformation and thin film peeling, etc. It is possible to form a high-quality semiconductor single crystal layer, which can contribute to the realization of a three-dimensional IC.

[Brief description of drawings]

1 and 2 are each for explaining a manufacturing process of a silicon single crystal layer. FIG. 1 is a plan view, FIG. 2 is a sectional view, and FIG. 3 is a process for explaining another method. Cross section,
FIG. 4 is a schematic diagram showing an example of a beam irradiation method, FIG. 5 is a schematic diagram showing the method of the present invention, and FIG. 6 is a diagram for explaining a conventional method. 11 …… single crystal silicon substrate (semiconductor substrate), 12 …… convex part, 13 …… SiO ₂ film (embedded insulating film), 14 …… polycrystalline silicon film (semiconductor thin film), 15 …… SiO ₂ film (cap) layer),
16 …… electron beam (energy beam), 17,19 …… SiO
₂ films, 18 …… Si ₃ N ₄ film.

Claims (6)

[Claims] 1. A convex portion is formed on the surface of a single crystal semiconductor substrate,
An insulating film is embedded in the surface of the substrate other than the convex portion, and then a polycrystalline or amorphous semiconductor thin film is formed on the entire surface, and the semiconductor thin film is irradiated with an energy beam having a predetermined intensity distribution to melt the thin film. In the method of manufacturing a semiconductor crystal layer to be recrystallized, the projections are formed on the surface of a single crystal semiconductor substrate in a plurality of dots, and the projections of the dots are arranged in an energy beam having a predetermined intensity distribution. On the other hand, the method of manufacturing a semiconductor crystal layer is characterized in that a region having high energy intensity is dense and a region having weak energy intensity is coarse. 2. The method for producing a semiconductor crystal layer according to claim 1, wherein the surface of the substrate is selectively etched by a reactive ion etching method as the step of forming the convex portion. . 3. The method according to claim 1, wherein in the step of forming the convex portion, a thermal oxide film is selectively formed on the surface of the substrate and then the thermal oxide film is removed. Of manufacturing a semiconductor crystal layer of. 4. The method for producing a semiconductor crystal layer according to claim 1, wherein the semiconductor thin film is formed by a CVD method. 5. The method for producing a semiconductor crystal layer according to claim 1, wherein the height of the convex portion is 5000 Å or more. 6. The method for producing a semiconductor crystal layer according to claim 1, wherein a laser beam, an electron beam or an ion beam is used as the energy beam.