JPS6161250B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor recrystallization method for selectively recrystallizing a predetermined region of a semiconductor substrate into a single crystal with a predetermined plane orientation.

Conventionally, many semiconductor devices, such as silicon semiconductor devices, use silicon wafers with {111} plane orientation. The reason for this is that the {111} plane is the most stable plane and has better crystallinity during epitaxial growth than silicon wafers with other plane orientations. However, in the case of elements with MOS structure (metal-oxide film-semiconductor structure),
{100} plane wafers are often used because the {100} plane has fewer surface states related to the threshold voltage (Vth), which is the lowest voltage at which the device's function begins to operate, than the {111} plane. In this way, each element has a plane orientation suitable for performing its respective function. However, in integrated circuits (ICs) or large-scale integrated circuits (LSIs) that incorporate elements with various functions, wafers with various surface orientations are used in one wafer or one chip. Currently, the function of one of the elements must be sacrificed.

Further, when manufacturing semiconductor devices, a single crystal wafer is often used, but only a small portion of the single crystal wafer is necessary for the semiconductor device to perform its functions. However, the current situation is that a huge amount of energy is expended for this portion, and the entire wafer has to be made into a single crystal.

In the former case, one wafer or one
It is extremely preferable if any part of a single chip can be selectively changed to any surface orientation suitable for the function of each element, since this will allow each element to perform its function satisfactorily. Also, in the latter case,
If single crystals with the required plane orientation can be formed only in the necessary portions of non-single crystal substrates such as polycrystals, amorphous materials, sintered bodies, etc., the process of pulling single crystals, which requires an enormous amount of power, can be eliminated. , it shortens the process and saves energy, and if unnecessary parts are made of polycrystalline, the electrical insulation between each element is also good.
It is also preferable for making semiconductor devices.

In view of the above-mentioned points, the present invention provides a semiconductor recrystallization method that enables selectively forming a single crystal region with a predetermined plane orientation in a necessary region in a semiconductor substrate using a simple method. be.

Hereinafter, a semiconductor recrystallization method according to the present invention will be explained.

First, the principle of the present invention will be explained using FIG. In the present invention, as shown in FIG. A semiconductor piece 3 made of the same material as the substrate 1 is formed with the plane orientation 'l'. This semiconductor sample is heated to a temperature higher than the metal-semiconductor eutectic point Tc and the semiconductor melting point Ts.
While maintaining a lower temperature Tx (Tc<Tx<Ts), at the same time the temperature on the substrate 1 side is high around that temperature Tx,
A temperature gradient is created so that the temperature on the semiconductor piece 3 side becomes lower, that is, Tx ₁ > Tx ₂ > Tx ₃ as shown in the figure. Thus, when the temperature near the metal piece 2 is lower than the melting point of the metal piece 2, melting starts from the two metal-semiconductor interfaces, and when the temperature near the metal piece 2 is higher than the melting point of the metal piece 2, the metal begins to melt. The entire piece begins to melt. Of the two interfaces between the liquid metal or solid solution and the solid semiconductor, more semiconductor can be dissolved at the higher temperature interface than at the lower temperature interface. Then, this melted semiconductor diffuses from the high-temperature boundary surface to the low-temperature boundary surface, and when it reaches the low-temperature boundary surface, it is not able to melt the semiconductor as much as the high-temperature boundary surface. Since this is not possible, semiconductors precipitate at this low-temperature interface. At this time, if there is a seed crystal, a single crystal will grow by inheriting the same plane orientation. Therefore, in the case shown in the figure, the liquid metal, strictly speaking, the molten metal-semiconductor, moves in the semiconductor substrate 1 toward the higher temperature side, and after moving, the plane orientation of the semiconductor is the one at the lower temperature side. The surface orientation of the semiconductor piece 3 is {h′k′l′}.

In Fig. 1, a single crystal substrate with {hkl} plane orientation is used as the semiconductor substrate 1, but even if the semiconductor substrate 1 is replaced with a polycrystalline semiconductor substrate, the crystal orientation of the semiconductor after the melt moves The orientation {h′k′l′} of the semiconductor piece 3 is inherited.

The present invention is based on the above principle to selectively form a single crystal region on a semiconductor substrate having a desired plane orientation different from that of the substrate.

Next, examples of the present invention will be described.

[Example] As shown in FIG. 2A, on a silicon single crystal substrate 10 having a {111} plane orientation and a thickness of approximately 300 μm, silminium (Al) was selectively deposited by a normal vacuum evaporation method to increase the thickness. Aluminum layers 11a and 11b with a thickness of about 30 μm are formed, and a silicon single crystal piece 12 having a {100} plane orientation and a silicon single crystal piece 13 having a {110} plane orientation are further formed on the aluminum layers 11a and 11b, respectively. The average temperature of the entire sample is 1000°C to 1050°C. Furthermore, for this sample, approximately
A temperature gradient of 100° C./cm was applied, and heat was transferred between the aluminum layers 11a and 11b in a vacuum for 1 hour.
Through this treatment, the sample had a structure as shown in FIG. 2B.
Next, the silicon pieces 12 and 13 with the {100} plane orientation and the {110} plane orientation selectively present on the substrate 10 and the aluminum layers 11a and 11b that have been thermally transferred to the back side of the substrate 10 are removed from this sample. As a result of mechanically cutting or scraping from both the upper and lower surfaces to the position of the chain line 14 and taking a transmission Laue photograph, the results show that region A in FIG. 2B is a single crystal with {111} plane orientation, and region B has { It was confirmed that it was a single crystal with a {100} plane orientation, and region C was a single crystal with a {110} plane orientation.

[Example] As shown in FIG. 3, tin (Sn) was selectively vapor-deposited using a normal vacuum evaporation method on a silicon single-crystal substrate 15 having a {100} plane orientation and a thickness of approximately 300 μm. Tin layers 16a and 16b with a thickness of approximately 30 μm are formed, and a silicon single crystal piece 17 having a {111} plane orientation and a silicon single crystal piece 18 having a {110} plane orientation are formed on the tin layers 16a and 16b, respectively. The average temperature of the whole sample is 1000℃~
The temperature should be 1050℃. Furthermore, a temperature gradient of approximately 100° C./cm was applied to this sample so that the substrate 15 side was higher than the silicon pieces 17 and 18 side.
Tin layers 16a, 16 in a high purity _N2 atmosphere for 10 minutes
b was thermally transferred. Through this treatment, the sample had a structure as shown in FIG. 3B. Next, the surface of the substrate 15 was mechanically cut or scraped to the position of the chain line 19 where the silicon pieces 17 with the {111} plane orientation and the silicon pieces 18 with the {110} plane orientation on the substrate 15 disappeared, and a reflection Laue photograph was taken. Result, Figure 3B
Region A′ is a single crystal with {100} plane orientation,
It was recognized that region B' was a single crystal with {111} plane orientation, and region C' was a single crystal with {110} plane orientation.

[Embodiment] As shown in FIG. 4A, a silicon single crystal piece 22 having a {100} plane orientation and a {111} plane orientation were deposited with aluminum layers 21a and 21b having a thickness of about 20 μm by a normal vacuum evaporation method. A silicon single crystal piece 23 having an orientation is placed on the respective aluminum layers 21a and 2 on a polycrystalline silicon substrate 20 with a thickness of approximately 500 μm.
1b is brought into selective contact with the substrate 20, and the average temperature of the entire sample is 1050°C to 1100°C.
so that it becomes Furthermore, a temperature gradient of about 100°C/cm was applied to this sample so that the polycrystalline substrate 20 side was higher than the single crystal pieces 22 and 23 side, and the aluminum layer 21 was heated in a high-purity N ₂ atmosphere for 1 hour.
a, 21b were subjected to heat transfer. Through this treatment, the sample had a structure as shown in FIG. 4B. Next, both the front and back sides of this sample were mechanically cut or scraped down to the chain line 24, and a transmission Laue photograph was taken.
Area A″ in Figure B is polycrystalline, and area B″ is {100}
It was confirmed that it was a single crystal with a plane orientation, and that region C'' was a single crystal with a {111} plane orientation.

Example [] As shown in Figure 5, the thickness was
A silicon single crystal piece 27 having a {100} plane orientation and a silicon single crystal piece 28 having a {111} plane orientation, on which aluminum layers 26a and 26b of 20 μm are deposited, are placed on a polycrystalline silicon substrate 2 with a thickness of approximately 500 μm.
The aluminum layers 26a and 26b are on the substrate 2
5 so that the average temperature of the entire sample is 1050°C to 1100°C. Furthermore, with respect to this sample, approximately
1× for 10 minutes with a temperature gradient of 100℃/cm
Aluminum layers 26a, 2 in a vacuum of 10 ^-5 Torr
6b was thermally transferred. With this treatment, the sample is shown in Figure 5B.
It became a structure like this. Next, the surface of this sample on the side of the single crystal pieces 27 and 28 was cut or scraped to the position of the chain line 29, and a reflection Laue photograph was taken. As a result, the region A'' in FIG.
B″ is a single crystal with {100} plane orientation, and the area
It was confirmed that C″ is a single crystal with {111} plane orientation.

The symbol {111} above is (111),
(111), (111), (111), (111), (111), (111
),
It is a general term for (111) planes.

Similarly, {100} is (100), (010), (001),
(100), (010), (001) planes, {110} is (110), (101), (011), (110), (110), (101
),
(101), (011), (011), (110), (101), (011
) is a general term for surfaces.

Furthermore, in the above embodiments, Si was used as the semiconductor and Al, Sn, etc. were used as the liquid substance, but the present invention is not limited thereto. For example, in addition to Si, semiconductors include Ge, GaAs, GaP, and SiC.
etc. can be used. Further, the substance that becomes a liquid does not necessarily have to have a melting point lower than that of the semiconductor, but may be any substance that forms a solid solution with the semiconductor and whose temperature at the eutectic point is lower than the melting point of the semiconductor. Furthermore, the substance that becomes this liquid is not limited to one type, but two types.
It is also possible to use more than one type.

As described above, according to the present invention, any part of a semiconductor single crystal substrate having a predetermined plane orientation can be selectively recrystallized into any plane orientation. Therefore, when this is applied to semiconductor integrated circuits, etc., it is possible to form a surface orientation suitable for the function of each element within one semiconductor wafer or one chip, and each element can perform its full function. An excellent semiconductor integrated circuit can be obtained.

Furthermore, since it is possible to form a single crystal with the necessary plane orientation in any part of a polycrystalline semiconductor substrate, in this case, the process of pulling the single crystal, which requires an enormous amount of power, is omitted. Not only can energy be saved, but since unnecessary portions remain as polycrystals, electrical insulation between each element is improved and a highly reliable semiconductor element can be obtained.

[Brief explanation of the drawing]

FIGS. 1A and 1B are process diagrams for explaining the principle of the present invention, and FIGS. 2A and B to 5A and B are process diagrams showing embodiments of the present invention, respectively. 1 is a semiconductor substrate, 2 is a metal piece, and 3 is a conductor piece having a predetermined surface orientation.

Claims (1)

[Claims] 1. A thin metal piece and a single crystal semiconductor piece made of the same material as the substrate and having a predetermined plane orientation are provided on a selected portion of the surface of the semiconductor substrate, and the temperature of the substrate is raised to a temperature equal to or higher than the metal-semiconductor eutectic point, and Semiconductor re-crystallization, characterized in that the temperature of the back surface of the substrate is made higher than the temperature of the surface of the substrate, the metal-semiconductor melt is moved to the back surface of the substrate, and the single crystal with the predetermined plane orientation is selectively recrystallized. Crystal method.