JP2002226289A - Method for manufacturing diamond membrane, and device for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to synthesize a diamond wafer without breakage by accurately keeping the temperature of a substrate constant by using powder, wherein the temperature is one of important variables in a method for synthesizing a diamond membrane by vapor phase synthesizing method. SOLUTION: A powder layer having fluidity provided under the substrate to by synthesized with a diamond membrane is provided one used as heat conductive medium between the substrate and a substrate holder. Because the heat conductivity between the substrate and the substrate holder is performed through the powder layer, the heat conductivity can be controlled through the kind of used powder, the shape of powder, the size, and the distribution of the sizes, and the variation of thickness of the powder layer. Consequently, the temperature of the substrate can be accurately controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for producing a diamond film, and more particularly to a method for synthesizing a diamond film by a vapor phase synthesis method, wherein the temperature of the substrate is accurately controlled so that the substrate can be formed during the synthesis. The present invention relates to a method and an apparatus for producing a diamond film free from destruction by preventing a rise in temperature and minimizing a temperature gradient on a horizontal surface of a substrate.

[0002]

2. Description of the Related Art The synthesis of a diamond film by a conventional vapor phase synthesis method is as shown in FIG. Diamond film 1
Is formed by evaporating a radical (radical) decomposed from the carbonized gas by the plasma 3 formed in the vacuum vessel 2 onto the substrate 4 in the form of a film in the process of moving to the substrate. The size of the substrate used at this time is several cm to 20 cm in diameter and 0.05 cm to 1 cm in thickness.
The material of the substrate is tungsten, molybdenum or silicon. Since the temperature of the upper surface of the substrate heated by heat or plasma is maintained at 700 ° C. to 1000 ° C., the substrate holder 5 on which the substrate is mounted is water-cooled, and the material is mainly copper having a good thermal conductivity. Produced in

[0003] In the synthesis of a diamond film by a vapor phase synthesis method, the substrate temperature (deposition temperature) is very important because it has a close relationship not only with the crystallinity of the film but also with the formation of stress that can cause the film to break. Being a variable, it must be precisely controlled.

There are two main problems in controlling the substrate temperature. One is that it is difficult to adjust the temperature to a specific temperature because the substrate is not heated independently but is held by the energy of the plasma itself. In this case, the substrate temperature is the input power
(When the substrate temperature is low) such as adjusting the flow rate of the water flowing through the substrate holder or adjusting the flow rate of the water flowing through the substrate holder, or inserting a disk of a certain thickness Can be adjusted. However, each of these methods may cause a change in the synthesis conditions (input power), and is not effective in controlling the substrate temperature, and is inferior in precision.

[0005] Another problem is that the substrate temperature rises during the synthesis and a temperature gradient is formed on the horizontal surface of the substrate, which leads to a serious problem of destroying the film during the synthesis. Becomes The cause is caused by the bending of the substrate during the synthesis. The cause of the bending can be summarized in two ways, one is due to the difference in thermal expansion coefficient due to the temperature difference between the upper and lower surfaces of the substrate, and the other is due to the stress approved for the film during the synthesis. . Explaining the former in more detail, the substrate is:
The substrate is heated by heat or plasma energy on the upper surface of the substrate, and the heat is released through a water-cooled substrate holder located on the lower surface of the substrate, so that the temperature of the substrate decreases from the upper surface to the lower surface. (FIGS. 2a and 2b). Therefore, the degree of thermal expansion of the upper surface of the substrate is larger than that of the lower surface, and the substrate is bent upward in a convex shape, and as a result, a space 8 is formed between the substrate and the substrate holder (FIG. 3A). Such development occurs during the initial stage of diamond film synthesis when the substrate starts to be heated.
That is, it may occur at a stage where a film is not formed.

[0006] In contrast, substrate deflection due to stresses applied to the film during synthesis occurs after diamond nucleates and grows on the substrate to form the film. The stress in the diamond film is generated because diamond includes lattice defects and forms a texture while being synthesized and grown on a different type of substrate. The stress is generally known as a tensile stress, and the substrate bends downwardly convexly due to such stress (FIG. 4B). Of course, the opposite is true when the stress approved for the diamond film is a compressive stress. It should be noted that if the approved stress on the diamond film is non-uniform depending on the location, the substrate will bend flexibly. When the substrate bends as described above, only a part of the lower surface of the substrate comes into contact with the flat substrate holder, and heat transfer from the substrate to the substrate holder is partially performed. Rise, and a temperature gradient may occur depending on the position of the substrate. For example, when the substrate bends upwardly in a convex shape, only the edge of the substrate comes into contact with the substrate holder, and the temperature of the central portion of the substrate is kept higher than the edge of the substrate (FIG. 3B).
Conversely, when the substrate bends downwardly in a convex shape, only the central portion of the substrate comes into contact with the substrate holder, and the temperature of the substrate edge is maintained higher than that of the substrate central portion. It is.

[0007] Further, the substrate temperature is also increased due to both of the two factors as described above. Such a temperature gradient on the horizontal surface of the substrate and an increase in the substrate temperature have a problem that the stress applied to the diamond film during the synthesis is increased and the diamond film is broken.

[0008]

DISCLOSURE OF THE INVENTION The present invention has been devised to solve the above-mentioned problems. In the present invention, there is provided a method for synthesizing a diamond film by a vapor phase synthesis method.
It is an object of the present invention to provide a method and an apparatus for producing a diamond film without destruction by accurately controlling the temperature of a substrate to prevent the temperature of the substrate from rising during synthesis and minimizing a temperature gradient on a horizontal surface of the substrate. There is.

[0009]

According to the present invention, there is provided a method for producing a diamond film by a vapor phase synthesis method, wherein the substrate on which the diamond film is deposited and the substrate are mounted. A method for producing a diamond film is provided, wherein a powder layer having fluidity is provided between the substrate and the substrate holder, and the powder layer is used as a heat transfer medium between the substrate and the substrate holder.

According to another aspect of the present invention, there is provided a gas-phase synthesis method including a substrate on which a diamond film is deposited, a substrate holder for holding the substrate, and a vacuum vessel receiving the substrate and connected to a plasma generator. In the apparatus for manufacturing a diamond film, the apparatus for manufacturing a diamond film may further include a powder layer provided between the substrate and the substrate holder.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 5 shows a specific configuration of the embodiment of the present invention. A powder layer 9 having a certain thickness was filled between the substrate 4 on which the diamond film 1 was synthesized and the substrate holder-5. In order to prevent the powder from flowing and leaking to the outside, a detachment preventing member such as a ring 10 is provided outside the contact portion between the substrate 4 and the substrate holder 5 to prevent the powder layer 9 from detaching outside. Is preferred.

According to the structure of the present invention, the heat of the substrate held at a high temperature of 700 ° C. to 1000 ° C. during the synthesis is as follows:
It is transmitted to the water-cooled substrate holder 5 via the powder layer 9.

In such a structure, if the substrate is bent and deformed for some reason during the synthesis, the powder flows in accordance with the deformation. Therefore, as shown in FIGS. Can be contacted. Therefore, since the heat of the bent substrate is uniformly transmitted to the substrate holder 5 as before the bending, the rise of the substrate temperature or the generation of the temperature gradient due to the substrate position can be minimized.

The powder layer used in the present invention can be appropriately selected by changing the type of powder (difference in thermal conductivity), the shape, size and size distribution of the powder, and the height of the powder layer. In particular, it is more efficient to use one having a diameter of 1 mm or less in terms of heat transfer control. As the material of the powder, metal or ceramic powder can be used.

[0016]

When synthesizing a diamond film according to the present invention, heat is transferred from the substrate to the substrate holder through the powder layer, so that the type of powder used (difference in thermal conductivity) and the By changing the shape, size and size distribution, and the height of the powder layer, heat transfer can be controlled and the temperature change of the substrate can be minimized.

Further, when the substrate is bent during the synthesis, the flow of the powder layer according to the bending keeps the contact between the substrate and the substrate holder to minimize the change in the substrate temperature during the synthesis of the diamond film. Was able to be transformed. When a substrate having a diameter of 4 inches and a thickness of 10 mm was used, the temperature rise of the substrate could be kept at 10 ° C. or less, and the temperature deviation depending on the substrate position could be kept at 5 ° C. or less. In this case, a thick diamond wafer with a diameter of 4 inches and a thickness of 2 mm
It could be synthesized without destroying C.

In the above, the present invention has been shown and described by taking a specific preferred embodiment as an example. However, the present invention is not limited to the above-described embodiment, and is not departed from the spirit of the present invention. Various changes and modifications may be made by those having ordinary knowledge in the technical field to which the present invention pertains.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a conventional method of synthesizing a diamond film by general vapor phase synthesis.

FIGS. 2A and 2B are diagrams showing a temperature gradient depending on the height of the substrate shown in FIG. 1;

FIGS. 3A and 3B are diagrams showing a substrate that is bent upward in a convex shape due to the degree of thermal expansion of the upper surface of the substrate due to a temperature gradient of the substrate.

FIGS. 4A, 4B, and 4C are diagrams showing the deflection of a substrate due to a tensile stress generated by a diamond film grown to a constant thickness on the substrate.

FIG. 5 is a view showing a structure in which a powder layer having a certain thickness is filled between a substrate and a substrate holder according to the first embodiment of the present invention.

FIGS. 6A, 6B, and 6C are schematic diagrams for explaining a change in a temperature gradient depending on a position of a substrate when a diamond film is formed under the same conditions as in FIGS.

Continuing on the front page (72) Inventor Gwang Yong Yoon South Korea, Seoul, Jung-Lang, Shin Nae Dong 654, Jinro Apartment 703-901 (72) Inventor Te Ki Lee South Korea, Seoul, Gangnam K, Nonhyung-Dong 105, Donghyung Apartment 1-301 F-term (reference) 4G077 AA03 BA03 DB16 EG03 EG04 TF01 TF03 4K030 BA28 FA10 GA02 KA23

Claims (6)

[Claims] In a method for producing a diamond film by a gas phase synthesis method, a powder layer having fluidity is provided between a substrate on which a diamond film is deposited and a substrate holder on which the substrate is placed, A method for producing a diamond film, wherein the layer is used as a heat transfer medium between a substrate and a substrate holder. 2. The method according to claim 1, wherein the powder layer is made of metal or ceramic powder. 3. The method according to claim 1, wherein the diameter of the powder forming the powder layer includes powder particles of 1 mm or less. 4. The diamond film according to claim 1, wherein a detachment preventing member for preventing detachment of the powder layer to the outside is provided outside a contact portion between the substrate and the substrate holder. Method. 5. The method according to claim 4, wherein the detachment preventing member is a ring. 6. An apparatus for producing a diamond film by a gas phase synthesis method, comprising: a substrate on which a diamond film is deposited; a substrate holder for holding the substrate; and a vacuum vessel for receiving the substrate and connected to a plasma generator. 3. The apparatus for producing a diamond film according to claim 1, wherein the apparatus further comprises a powder layer provided between the substrate and the substrate holder.