JPH07157393A - Production of vapor grown self-standing film and substrate device for its production - Google Patents

Abstract

PURPOSE:To provide a method for producing a vapor grown selfstanding film by easily peeling the vapor grown film formed on a substrate from the substrate and a substrate device usable repetitively in execution of this method. CONSTITUTION:Tensile stress or compressive stress is previously mechanically applied by pressurizing means, such as a pair of lock screws 2, on the two side faces 1b not adjacent to each other of the substrate 1 and on the side nearer the front or rear surface side than the intermediate of the front surface 1a and rear surface 1c of the substrate 1. The vapor grown film is formed on the front surface 1a of the substrate 1 in this state and thereafter, the stress applied on the front surface 1a of the substrate 1 is released, by which the vapor grown film is peeled from the substrate 1 and the vapor grown self- standing film is produced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a vapor-phase growth free-standing film separated from a substrate and a substrate device used therefor.

[0002]

2. Description of the Related Art The vapor phase growth method includes physical vapor phase growth methods (PVD method) such as vapor deposition, sputtering, and ion plating, and chemical vapor phase growth method utilizing chemical reaction of source gas. (CVD method), which has been conventionally used for manufacturing semiconductor devices and solar cells, but recently, a thin film of ceramics such as diamond or silicon nitride has been actively used as a coating film for tools. It is being appreciated.

In order to form a thin film of diamond or the like by the vapor phase growth method, a substrate that supports the growth of the thin film is required. In the case of the coating film of the tool, the substrate itself is the substrate of this substrate, but a substrate made of the same or the same kind of substance as the substance for vapor phase growth is generally used. Further, a thin film of diamond or the like is usually used as it is attached to a substrate, and therefore it is desired that its adhesion strength be strong.

By the way, it has been studied to use a diamond thin film as a heat sink for heat radiation of a semiconductor laser or the like, but it goes without saying that a heat sink made of only diamond is desirable for that purpose. As described above, there is an increasing demand for a free-standing film that is a vapor-phase growth film but is not supported by a substrate. After vapor-depositing a thin film on a substrate, the vapor-deposited self-supporting film was manufactured by a method of dissolving and removing only the substrate.

[0005]

As described above, in the case of manufacturing a vapor phase growth free-standing film which is a vapor phase growth film but is not supported by the substrate, an unnecessary substrate is finally necessary for the vapor phase growth. In addition, the substrate has to be dissolved in order to obtain a free-standing vapor-phase growth film, so the cost of dissolving the substrate is high, and the substrate itself is disposable, resulting in a very high substrate cost. was there.

Of course, the cost can be reduced by considering the material of the substrate such that the vapor growth film spontaneously peels off from the substrate after the vapor growth. However, when the adhesion between the substrate and the vapor phase growth film is not good, there is a problem that the vapor phase growth film is peeled off from the substrate due to internal stress during the vapor phase growth,
To date, no substrate material has been found that can be spontaneously separated from the substrate after the vapor phase growth film to obtain a free-standing film.

Further, since the vapor phase growth is generally performed at a relatively high substrate temperature, thermal stress is generated in the substrate and the vapor phase growth film when cooled to room temperature after the vapor phase growth. It is theoretically possible to control the internal stress of the vapor phase growth film so that the vapor phase growth film separates from the substrate when cooled to around room temperature due to this thermal stress.

However, the thermal stress and the internal stress differ depending on the material and thickness of the substrate and the vapor phase growth film, and since these stress changes are not so large, the material and thickness of the substrate and the vapor phase growth film do not matter. Regardless of this, controlling the thermal stress and the internal stress of the vapor phase growth film so that the vapor phase growth film spontaneously separates from the substrate when cooled to around room temperature is said to be unachievable in reality. I have no choice.

In view of such conventional circumstances, the present invention simply peels a vapor phase growth film formed on a substrate from the substrate regardless of the material and thickness of the substrate and the vapor phase growth film, It is an object of the present invention to provide a method by which a vapor-phase growth free-standing film can be obtained, and a substrate device which can be repeatedly used to carry out this method.

[0010]

In order to achieve the above object, the method for producing a vapor-phase growth free-standing film provided by the present invention mechanically preliminarily applies tensile stress or compressive stress to a substrate, and this stress is applied. After forming the vapor phase growth film on the substrate surface in the state
The vapor deposition film is peeled off from the substrate by releasing the stress applied to the substrate surface.

Further, in the method for producing a self-supporting film of vapor phase growth according to the present invention, the flat surface of the substrate is curved in a concave shape or a convex shape, or the concave or convex surface is curved in a flat shape, and this curved state After the vapor phase growth film is formed on the surface of the substrate, the warp of the substrate surface is returned to the original state so that the vapor phase growth film is peeled from the substrate.

As a substrate apparatus for carrying out the above method, as shown in FIG. 1, a rectangular plate-shaped substrate 1 used for vapor phase growth and two side faces 1b of each side face of the substrate 1 which are not adjacent to each other. In addition, there is a device including a pressurizing unit that pressurizes the front surface side or the rear surface side of the substrate between the front surface 1a and the back surface 1c, for example, a pair of tightening screws 2.

[0013]

In the method of the present invention, the internal stress of the vapor phase growth film or the thermal stress generated in the substrate and the vapor phase growth film during cooling after the vapor phase growth is not controlled, but mechanical stress is applied to the surface of the substrate. Since the stress is applied (the surface of the substrate is warped in appearance), it is extremely easy to apply and release the stress to the substrate, and the magnitude of the stress applied to the substrate in advance can be easily adjusted.

Therefore, in the method of the present invention, the magnitude of the stress applied to the substrate is changed so that the vapor phase growth film is separated from the substrate when the stress applied to the substrate is released and the substrate itself is not destroyed. To set. In order for the vapor phase growth film to peel off from the substrate, it is necessary to give a stress to the substrate in advance that is larger than the adhesion strength between the substrate and the vapor phase growth film.
Since its size depends on the material and thickness of the vapor phase growth film, the material of the substrate, and the like, it can be experimentally obtained in advance according to these conditions.

The apparatus for carrying out the method of the present invention is an apparatus capable of mechanically applying a tensile stress or a compressive stress to the surface of a substrate, thereby imparting a warp to the surface of the substrate, and releasing the stress or the warp. I wish I had it. Therefore, specifically, a substrate device provided with a pressing means for pressing the side surface of the substrate as described above, a device for bending the substrate surface by vacuum suction, or the like may be used.

Above all, the substrate device provided with the above-mentioned pressurizing means is preferable because the magnitude of the stress applied to the substrate can be easily adjusted by controlling the pressing force. Although a pusher or the like can be used as the pressurizing means, it has a drawback that the device becomes large in size, and therefore, as shown in FIG. It is preferable to use at least one pair of tightening screws 2 attached to the front surface side or the back surface side rather than the middle between the front surface 1a and the back surface 1c.

Specifically, the tightening screw 2 is provided between the two tightening pieces 2a and the two tightening pieces 2a which are in contact with the front surface 1a side or the back surface 1c side of the two side surfaces 1b of the substrate 1, respectively. Of the bolt portion 2b supported by being passed over the two fastening pieces 2a so that the distance between the two can be changed, and a nut portion 2c screwed to the outside of the fastening piece 2a at least at one end of the bolt portion 2b.
It consists of

In FIG. 1, two screws (1
4 pieces of tightening pieces 2a are illustrated with a pair of tightening screws 2. However, one long piece of tightening piece along the side surface 1b to be pressed is used, and one piece of this long piece of tightening piece is paired. It is also possible to provide two tightening pieces 2a for each pair of tightening screws 2 by passing over the two bolt portions 2b. Further, the bolt portions 2b may movably penetrate the fastening pieces 2a at both end portions, and the nut portions 2c may be screwed to the outer sides of the fastening pieces 2a at each end portion. The end on one side can be fixed to the fastening piece 2a.

Next, taking as an example a square substrate which originally has a flat surface, the case where a stress is applied to the substrate using the substrate device having the tightening screw 2 shown in FIG. 1 will be specifically described. Attach the pair of tightening screws 2 to the two side surfaces 1b of the substrate 1 that are not adjacent to each other.
Attached to each back surface 1c side (closer to the back surface) (bolt portion 2b
Is along the side surface adjacent to the side surface 1b), the nut portion 2
When c is rotated and the two opposite side surfaces 1b are pressed by the fastening pieces 2a, the originally flat surface 1a warps in a convex shape as shown in FIG. 2, and the tensile stress is applied to the convex surface 1a. Is given.

Further, a pair of tightening screws 2 are attached to the two side surfaces 1b of the substrate 1 which are not adjacent to each other on each surface 1a side (close to the surface),
When the nut portion 2c is rotated to press the opposite two side surfaces 1b with the tightening pieces 2a, the flat surface 1a warps concavely as shown in FIG. 3, and the concave surface 1a is compressed. Stress is generated. Then, by releasing the pressure applied by the tightening screw 2, these stresses are released, and the warp of the surface 1a of the substrate 1 can be eliminated to restore the original flat state.

It should be noted that although the method and substrate apparatus of the present invention can be used for the production of all kinds of vapor-phase growth free-standing films,
In the case of producing a vapor phase self-supporting film of diamond, a silicon substrate having good adhesion to diamond is suitable. Further, since it is desirable that the vapor growth film does not adhere to the tightening screw or other pressurizing means, in the case of the self-supported film of diamond vapor growth, the molybdenum tightening screw or other such that the adhesion to the diamond is extremely poor. It is preferable to use a pressurizing means.

[0022]

[Example] As shown in FIG. 1, 25 mm square and 5 mm thick
The two side surfaces 1b of the substrate 1 made of Si, which are not adjacent to each other, are brought into contact with the tightening pieces 2a of the tightening screws 2 from the middle of the front surface 1a and the back surface 1c of the substrate 1 to the back surface side, and the opposite tightening pieces 2
After the bolt portion 2b of the tightening screw 2 is passed through the hole of a, the nut portion 2c is provided at both ends of the bolt portion 2b on the outer side of the fastening piece 2a.
2 side faces 1 facing each other with a tightening pressure of 1.5 GPa
The surface 1a is curved in a convex shape by tightening b,
Tensile stress was generated on the surface 1a of the substrate 1. The tightening screw 2 including the tightening piece 2a, the bolt portion 2b, and the nut portion 2c is made of Mo.

The substrate 1 whose tensile stress was applied to the surface 1a as described above by the tightening screw 2 was placed on the support plate 3 on the cooling support base 4 of the film forming apparatus as shown in FIG. The heating element 5 made of W filament arranged above the substrate 1
H ₂ while maintaining the substrate temperature at 850 ° C.
Gas 1000 cc / min and CH ₄ gas 10 cc
The diamond was grown for 50 hours on the surface 1a of the substrate 1 to which the tensile stress was applied by supplying at a flow rate of / min.

After completion of the vapor phase growth, the substrate 1 is taken out from the film forming apparatus, cooled to room temperature, and the tightening screw 2 is removed from the substrate 1 to release the stress, and the vapor phase growth film of diamond having a thickness of 50 μm is naturally formed. Peeled from the surface 1a of the substrate 1,
A free standing diamond vapor phase growth film without cracks or damage was obtained. Also, the Si substrate 1 was maintained in its original state without defects, and could be repeatedly used as a substrate for vapor phase growth.

For comparison, diamond was vapor-grown under the same conditions as above except that the tightening pressure of the tightening screw 2 was set to 0.5 GPa. After the completion of vapor phase growth, the tightening screw 2 was removed from the substrate 1 cooled to room temperature, but the vapor phase growth film of diamond remained attached to the substrate 1 and was not peeled off. Moreover, when diamond was vapor-deposited under the same conditions as above except that the material of the substrate 1 was Mo, the diamond did not grow by adhering to the substrate 1 and a free-standing film could not be obtained.

[0026]

According to the present invention, the material and thickness of the substrate and vapor phase growth film can be determined simply by mechanically applying stress to the substrate before vapor phase growth and releasing the stress after vapor phase growth. Regardless, the vapor phase growth film can be peeled off from the substrate to obtain a vapor phase growth free-standing film.

Moreover, since the substrate returns to its original state by the release of stress and is not consumed or lost, the substrate can be repeatedly used for vapor phase growth. Therefore, the substrate cost and the vapor phase growth free-standing film can be increased. It is possible to significantly reduce the manufacturing cost.

[Brief description of drawings]

FIG. 1 is a perspective view showing a specific example of a substrate device according to the present invention in which a tightening screw is attached to a side surface of a substrate.

FIG. 2 is a schematic side view of a substrate for explaining a state where the substrate surface is warped in a convex shape by applying a tensile stress to the surface.

FIG. 3 is a schematic side view of a substrate for explaining a state where the substrate surface is warped in a concave shape by applying a compressive stress to the surface.

FIG. 4 is a schematic side view of a film forming apparatus for vapor-depositing diamond on a substrate by using the substrate apparatus of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 1a Front surface 1b Side surface 1c Back surface 2 Tightening screw 2a Tightening piece 2b Bolt portion 2c Nut portion 3 Support plate 4 Cooling support base 5 Heating element

Claims (6)

[Claims] 1. A method for producing a free-standing vapor-phase growth film, comprising forming a vapor-phase growth film on a substrate surface by vapor-phase growth method and then peeling the vapor-phase growth film from the substrate, wherein the substrate is mechanically stretched in advance. Characterized by applying a stress or a compressive stress, forming a vapor phase growth film on the substrate surface in the state where the stress is applied, and then peeling the vapor phase growth film from the substrate by releasing the stress applied to the substrate surface. A method for manufacturing a vapor-grown free-standing film. 2. A method for producing a free-standing vapor-phase growth film, comprising forming a vapor-phase growth film on a substrate surface by vapor-phase growth method and then peeling the vapor-phase growth film from the substrate. Warp concave or convex, or warp a concave or convex surface to a flat surface, form a vapor phase growth film on the warped substrate surface, and then restore the warp of the substrate surface to the original state A method for producing a self-supported vapor-phase growth film, which comprises peeling the vapor-phase growth film from the substrate. 3. An external pressure is mechanically applied to at least two side surfaces of the rectangular plate-shaped substrate which are not adjacent to each other and to the front surface side or the back surface side of the middle of the front surface and the back surface of the substrate,
2. The vapor growth film is formed on the surface of the substrate which is warped by the external pressure, and then the external pressure is released to peel the vapor growth film from the substrate.
Or the method for producing a vapor-phase growth free-standing film according to item 2. 4. A rectangular plate-shaped substrate used for vapor phase growth, and a pressure applied to at least two side surfaces of each side surface of the substrate which are not adjacent to each other and to which pressure is applied to the front surface side or the back surface side rather than the middle of the front surface and the back surface of the substrate. A substrate device for producing a vapor-phase growth free-standing film, which comprises a pressure means. 5. The pressurizing means is at least one pair of tightening screws, and the tightening screws are two tightening pieces that come into contact with the front surface side or the back surface side of the two side surfaces of the substrate, respectively. And a nut portion screwed to the outer side of the fastening piece at least at one end of the bolt portion so as to be able to change the distance between the two fastening pieces. The substrate device for manufacturing a vapor-phase growth self-supporting film according to claim 4, which is characterized in that. 6. The vapor-grown self-supporting film according to claim 4, wherein the substrate is made of silicon and the tightening screw is made of molybdenum, which is used for producing a vapor-phase grown self-supporting film of diamond. Substrate device for manufacturing.