JPS5928327A - Forming method of single crystal semiconductor film - Google Patents

Abstract

PURPOSE:To obtain a single crystal Si film at a low temperature on a glass substrate of low cost by such an arrangement wherein when crystals composed of an alloy of Au and Si are caused to educe on an amorphous substrate, the orientation of crystals is controlled by the repetitive patterns of Au film. CONSTITUTION:On a quartz glass substrate 11, a film of Au 12 which forms eutectic crystal with Si is caused to adhere thereto, a resist film of specific pattern 13 is provided thereon, and spatter etching is processed on exposed parts of the film 12 and a repetitive pattern of polygon 14 having a vertical angle which is a multiple of about 60 deg. is obtained. Here, the pattern 14 shall be a trapezoid having vertical angles of 60 deg. and 120 deg. and the distance between opposing sides shall be approx. 1mum, and pitch shall be approx. 1.2mum. Next, the substrate 11 is heated up to a temperature higher than the eutectic temperature of Si and Au, and Si is caused to adhere by evaporation, and eutectic alloy of Si-Au is caused to generate between patterns 14, and single crystal Si layer 19 is caused to generate of which crystal direction is aligned, by using surplus Si 18 adhered to the pattern 14. At the same time, Au is moved from the alloy 17 and the desired Si-Au thin film 20 is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming a single crystal semiconductor film, and particularly to a method for growing a single crystal film of a semiconductor material such as silicon on an amorphous substrate such as glass.

Conventionally, the graphoepitaxy method is known as a method for growing silicon single crystals on an amorphous substrate (M, W
, G@Is, D, C, FJanders and H,
I.

8m1th, AppIIi@d Physics Le
Volume 33, page 77 (197?)). In this method, a depth of 1100 is formed at a pitch of 3 μm on an amorphous insulating substrate.
Amorphous silicon is deposited on the soil by chemical vapor deposition (CVD'I), and then crystallized by laser annealing. The cut grooves control the crystal orientation during crystallization.

However, in this method, when the laser output for annealing is increased in order to improve crystallinity, the cross-sectional shape of the groove described above changes from a rectangular shape due to heat. Furthermore, since 1 u (slo2 or 513N4) of storage is required during crystallization, the process is complicated.

In order to solve the above drawbacks,
eJournaA' of Applied PhAc5
Volume 20 L9o3~L de oz page (1911) and Tokkai Sho&? -10, 2, 2'1, as shown in Figure 1, a metal such as Au that causes a eutectic reaction with silicon at low temperatures is used in the groove
A method is shown in which a metal film 3 is formed by depositing on the entire surface of a carved quartz substrate l, and then a silicon single crystal is grown on this metal film 3 at a low temperature.

However, in the method of Mori et al., since <///> has the property of being oriented in the direction perpendicular to the substrate, in order to obtain a single crystal film, the groove λ on the substrate l must be 109.
, it is necessary to precisely process it so that it has an angle of t°,
Furthermore, it is necessary to form the grooves so that the grooves intersect with each other at 400 degrees, which has the disadvantage of complicating the process.

In addition, reactive sputter etching is used to process grooves, but it is extremely difficult to form grooves with an ideal cross-sectional shape, so there is a limit to the improvement of crystallinity. .

Therefore, an object of the present invention is to provide a method for forming a single crystal semiconductor thin film with good crystallinity.

Another object of the present invention is to provide a method for forming a single crystal semiconductor thin film that is easy to manufacture.

Still another object of the present invention is to provide a method for forming a single crystal semiconductor thin film that can be manufactured at low temperatures. A metal that becomes eutectic or a compound with the semiconductor to be crystal-grown is formed into a polygonal repeating figure having an apex angle that is an integral multiple of too, and the semiconductor material is placed on the substrate having the formed gold M'. is deposited to form a single crystal semiconductor thin film.

In a second embodiment of the present invention, a metal to be eutectic or a compound with a semiconductor to be crystal-grown is formed into a repeating polygonal shape having an apex angle of an integral multiple of 600 on a planar amorphous substrate, A semiconductor material is deposited on the substrate having the shape metal to grow a crystalline semiconductor film, the metal is then removed, and a new single-crystal semiconductor film is epitaxially grown on the single-crystal semiconductor film. let

Here, silicon can be used as the semiconductor. As a repeating figure, for example, an equilateral triangle or 40
It can be a parallelogram with apex angles of and /J.

In preferred IJ embodiments of the present invention, the deposition of the semiconductor material is performed below the eutectic temperature of the semiconductor and metal.

The present invention will be described in detail below with reference to the drawings.

Figures -A to -F show an embodiment of the sequential steps of the method of the present invention, in which a single crystal of a semiconductor is to be grown on a substrate as shown in Figure 15, for example a quartz glass substrate. A metal film/2 that becomes a crystal or a compound, for example, a gold film/2 when the semiconductor/body is silicon, is formed to a thickness of, for example, 1000 A using a vapor deposition method to obtain the structure shown in Figure 2B. .

He formed a resist pattern 13 of a predetermined shape on this structure to obtain the structure shown in FIG. A metal (gold in this case) pattern /lI of a polygonal repeating figure having apex angles that are integral multiples of angles is formed to obtain the structure shown in Fig. 21).

Here, the shape of the gold pattern /41 is shown in FIG.
: 5 L, t=o0 and/, has an apex angle of 2/7°,
The distance between opposing sides is 1 μm, and the pitch of the diamond engraving pattern /& is 1. −μm.

Incidentally, in order to obtain the structure shown in Fig. 1, 2D, a method using lift-off may be used in addition to the processing shown in Figs. 28, 2C, and 2C. That is, a resist pattern /3 having a thickness of O and 7 μm, for example, is formed in a predetermined shape on a nine substrate 11 to obtain the structure shown in FIG. 41A. Next, a gold film /6 is deposited on this structure by vapor deposition or the like to a thickness thinner than the resist pattern /3 to obtain the structure shown in FIG. 98. Thereafter, the gold film /6 on the resist pattern /3 is removed by a lift-off process along with the resist pattern /& using acetone or the like to obtain a structure having a gold pattern /lI- as shown in FIG. 2D.

The following method can be used to form the resist pattern /3 or /3 when obtaining the gold pattern structure shown in FIG. First, a resist (for example, AZ/330 J manufactured by Sibley) is applied onto a quartz glass substrate 11, and then, for example, H,
The resist is exposed in the form of a grating with laser beams from -Cd'/- lasers or the like being superimposed and interfered with. Next, the substrate // is rotated to 0, and the same superimposed and interfered laser beams are irradiated to perform another grating-like exposure superimposed on the grating-like exposure. Next, when developing processing is performed,
The overlapping exposed portions of the resist are removed in a rhombus shape, forming a resist pattern 13 or 13 in a predetermined shape.

Next, the substrate on which the gold pattern shown in FIG.
As shown in FIG. 2E, silicon S1 as a semiconductor material is heated at several A/sec, for example J A/s e
is deposited on the entire surface of such substrate // at a deposition rate of e.

The deposited silicon sequentially reacts with gold and melts into a gold film at a certain concentration to form a 5l-Au eutectic alloy/γ. As the deposition progresses, excess silicon is deposited on the substrate ll with sign/g.
Precipitation begins as shown in . In this precipitation, the crystals of precipitated silicon/S are perpendicular to the substrate (//
/ :>, and the crystal orientation in the horizontal direction with respect to the substrate // is aligned due to the shape of the gold<turn/lI, so a single crystal silicon film 19 is formed on the substrate //. Gold is transferred onto this single crystal silicon crotch/9 to form a thin film of S1-Au eutectic alloy, resulting in the layer structure shown in FIG. 2F. The thickness of the single crystal silicon film 19 at this time was X)00A.

Elemental analysis of the thus obtained layer structure shown in Figure 2F in the depth direction using electron microprobe analysis revealed that silicon wI/9 was present upward from the substrate l/ side. S1-A on top of silicon layer/9
It was confirmed that there was a u-eutectic alloy layer. Furthermore, as a result of examining the crystallinity of the single crystal silicon film 19 by transmission electron diffraction, it was found that a single crystal with <II/> axis was formed in the direction perpendicular to the substrate, as shown in FIG. It was confirmed that there is.

In addition, in the structure of FIG. 22, 5l-A and the eutectic alloy layer may be removed as necessary.

By the way, if the planar shape of the gold pattern/lI is a polygon whose apex angle is an integral multiple of about 600, it is presumed that single crystal silicon can be grown for the following reason. That is, the deposited silicon reacts with gold to form an alloy, but since the substrate is kept above the eutectic temperature, the 5l-A alloy becomes molten. As silicon vapor deposition progresses, silicon crystals are finally deposited in the 5l-Au alloy.

The precipitated crystal is an equilateral triangle because the <iii> plane is oriented parallel to the substrate surface, and the orientation within the substrate surface is such that the crystal is J- and the surface tension received from the molten alloy is minimized. Orient.

Therefore, the shape of the gold pattern /lI is not necessarily limited to the above-described embodiment, and the simplest pattern is a repeating equilateral triangular pattern as shown in FIG. There are various other variations such as the pattern shown in FIG. 7, and the apex angle of the polygon does not have to be exactly 600 or an integral multiple thereof.

In the above examples, gold was used as the metal film, but other materials that form a eutectic or compound with silicon, such as aluminum, silver, copper, platinum, nickel, palladium, gallium, and indium, may also be used. It can be anything.

The temperature of substrate heating is set so that the semiconductor is deposited on the substrate.
It is necessary that the temperature be at or above the eutectic temperature or compound formation temperature.

Further, in this embodiment, a vapor deposition method is used to supply silicon, but other methods such as chemical vapor deposition (CVD), sputtering, plasma CVD, etc. may also be used.

Furthermore, if impurities are also supplied at the same time as silicon supply,
It is also possible to grow crystals containing impurities. In order to grow silicon with good crystallinity, the thickness of the metal film only needs to be several hundred square meters or more. In addition, after forming a repeating metal pattern, the thickness is such that the above-mentioned metal pattern is transferred to the entire surface, for example! 00
The same type of metal may be uniformly deposited to a thickness of about A or less, and then silicon may be deposited.

Furthermore, it goes without saying that a high-purity silicon crystal film can be grown by the usual silicon epitaxy method on the crystal film grown by the method described above.

The repeating pitch of the metal film pattern may be several plus micrometers or less, and preferably about 1 to 3 micrometers.

Further, as the substrate, in addition to quartz glass, ordinary glass, a round metal plate made of Si3N4, stainless steel, or the like may be used.

As explained above, in the present invention, crystals are precipitated from an alloy of metal and silicon, and the orientation of the crystals is controlled by repeating the film review and the shape of the pattern to form a P-type single crystal silicon film. A single crystal film can be obtained even on a flat substrate.

Furthermore, in the present invention, since the eutectic temperature is low, crystals can be grown at low temperatures, and therefore inexpensive glasses such as soda glass and Pyrex can be used.

As described above, the present invention is effective for manufacturing low-cost solar cells, thin film transistors, transistors, three-dimensional LSIs, and the like.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of the conventional method of forming a single crystal film, Figs. 2i to 2F are cross-sectional views showing an example of the sequential steps in the present invention, and Fig. 3 shows the repeated metal pattern. 1A and 98 are cross-sectional views for explaining the process of forming a metal pattern by lift-off method, FIG. 5 is an electron diffraction photograph showing the structure of the crystal grown according to the present invention, and FIG. FIG. 7 and FIG. 7 are diagrams showing other examples of repeating metal patterns. /...Quartz substrate, λ...Groove, 3...Metal film, //...Amorphous substrate, 7.2...Gold film, /3...Resist pattern, /lI・...Repetitive metal pattern, B...Resist pattern 1, /6...Gold film, /7.-6L-Au eutectic alloy 1 71i'...Precipitated silicon crystal, /q...Single crystal silicon +b, 〃...5i-Au eutectic alloy Ru Patent applicant Nippon Telegraph and Telephone Ilmo Co., Ltd.

Claims (1)

[Scope of Claims] l) A step of forming a metal that becomes a eutectic or a compound with a semiconductor whose crystal is grown on an amorphous substrate into a repeating polygonal shape having an apex angle that is a multiple of approximately to0; A method for forming a single-crystal semiconductor film, comprising the step of thereafter depositing a semiconductor material on the substrate having metal in the shape of the figure to grow a single-crystal semiconductor film. g) A step of forming a metal that becomes eutectic or a compound with a semiconductor crystal grown on an amorphous substrate into a repeating polygonal shape having an apex angle that is a multiple of approximately bd'; A step of depositing a semiconductor material on a substrate having a shaped metal to grow a single crystal semiconductor film, followed by a step of removing the metal, and epitaxially growing a new single crystal semiconductor film on the single crystal semiconductor film. A method for forming a single crystal semiconductor film, comprising the steps of: 3) A method for forming a single crystal semiconductor film according to claim 1 or 1, wherein the semiconductor is silicon. ll) The method for forming a single crystal semiconductor film according to any one of claims 1 to 3, wherein the repeating shape is an equilateral triangle. 3) In the method for forming a single crystal semiconductor film according to any one of claims 1 to 3, the repeating shape is a parallelogram having an apex angle of 60 and l〃0. Characteristic single crystal semiconductor film formation method. B) In the method for forming a single crystal semiconductor film according to any one of claims 1 to 5, the deposition of the semiconductor material is performed at a temperature equal to or higher than the eutectic temperature of the semiconductor and the metal. Characteristic single crystal semiconductor film formation method.