KR20000024497A - Diamond thin film and bulk formation method by laser ablation combined with high voltage discharge plasma CVD - Google Patents

Abstract

PURPOSE: A method for preparing a diamond thin film and bulk is provided, which combines laser ablation and high voltage electric discharge plasma CVD (chemical vapor deposition) method to increase the thin film deposition rate. CONSTITUTION: The diamond thin film and bulk are prepared by appling high voltage between two separated pure graphite electrodes to generate an electrical discharge plasma, thereby to excite hydrogen gas into the excited hydrogen atom and to mix the exited hydrogen atom with a carbon atom released from a cathode; simultaneously radiating laser beam(2) onto the flat graphite target (a cathode)(6) to make carbon particles with high kinetic energy emerge from the inside of plasma to a substrate(11) on the anode(8), thereafter the carbon particles be mixed with the excited carbon atom; and fixing the mixed carbon particles and carbon atom onto the substrate positioned at the very center of plasma.

Description

Diamond thin film and bulk formation method by laser ablation combined with high voltage discharge plasma CVD}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device and method for forming a high quality diamond thin film or bulk by a new method of the lasma mixing method in which the laser ablation method and the high voltage discharge plasma CVD method are specifically combined. In more detail, in the present invention, a process of specifically combining the above two methods is complementary, and the high-voltage discharge plasma density is increased and the thin film deposition rate efficiency is increased so that high-quality diamonds can be deposited on the substrate in a shorter time. Enclosing the plasma zone in a special heat-treated glass reactor (FIG. 4) to form, and in order to make the atomic hydrogen effectively function on the substrate during the deposition process and to increase the generation efficiency of atomic hydrogen The present invention relates to a device and a method for forming a high quality diamond thin film or bulk, further comprising supplying hydrogen gas to a plasma center, that is, a special guide tube to be supplied near a substrate where a diamond thin film is formed. .

Conventionally, in order to form a diamond thin film on a board | substrate, the plasma CVD method in constant hydrogen atmosphere was mainly used. When diamond is grown in a hydrogen atmosphere, it is known that hydrogen atoms promote formation of sp 3 carbon having a diamond structure on a substrate, thereby obtaining a diamond film having high quality. On the other hand, in recent years, in addition to the above-described plasma CVD method, the laser ablation method has a simple structure of the apparatus, and because of the high kinetic energy of the particles emitted from the graphite target, it is possible to grow crystals at lower substrate temperatures. It is being applied to thin film growth.

1 and 2 are schematic diagrams showing a process of forming a diamond thin film by a laser ablation method and a plasma CVD method. As shown in FIG. 1, in a conventional laser ablation method, an excimer laser or the like is shown. The laser beam 2 generated from the laser generation source 1 is collected by the lens 3 and irradiated onto the surface of the graphite target 6 which is slowly rotating by the driving motor 5 located in the vacuum chamber 4, Irradiation of the laser beam causes particles protruding from the surface of the graphite target 6 to form a diamond thin film on the substrate 11 positioned on the substrate heater 10. As shown in FIG. 2, in the conventional plasma CVD method, when a high pressure is applied between two flat high purity graphite electrodes 6 and 8 spaced apart from each other, a large number of excited carbon particles are released from the cathode 6. These particles are deposited on the substrate 11 located above the substrate heater 10 to form a diamond thin film.

However, in the conventional method of forming a diamond thin film on a substrate by using the above laser ablation method, the carbon particles emitted by irradiating the laser target 2 on the graphite target 6 are discharged onto the substrate 11. In the deposition, the diamond phase (sp ³ ) and the graphite phase (sp ² , sp) were mixed and had a limitation that a high quality diamond thin film could not be obtained. Due to these technical limitations, the diamond thin film deposited by the laser ablation method is inferior to the thin film obtained by the plasma CVD method (mechanical, thermal, electro-electronic properties, etc.). Despite the advantage of being able to deposit at a low substrate temperature as described above, the situation is not widely used industrially. In addition, the diamond thin film obtained by the plasma CVD method alone has a disadvantage in that the production cost is high due to the high quality, but the time required for obtaining the diamond (about 40-50 hours to grow a 0.1mm diamond).

The present invention was devised to improve the above problems of the prior art, and an object of the present invention is to overcome the inferior characteristics mentioned above when forming a diamond thin film on a substrate by a laser ablation method, When forming a diamond thin film on the substrate, the purpose of the present invention is to provide a method of specially designed device to maximize the excitation efficiency and vapor deposition efficiency to form a better quality diamond thin film and bulk in a shorter time .

The present inventors firstly, in the plasma CVD method, when a diamond thin film is formed on a substrate, hydrogen atoms in the surroundings inhibit the formation of carbon in the graphite phase (sp or sp ² ) and promote carbon formation in the diamond phase (sp ³ ). Secondly, the laser ablation method is complementary to the fact that the structure of the device is simple and the kinetic energy of the emitted carbon particles is high so that crystallization can be achieved even at low substrate temperature. When the diamond thin film is formed while the method is performed in the same chamber at the same time, the present invention is completed in the judgment that a high quality thin film and bulk containing a pure diamond phase can be obtained on a substrate at a lower substrate temperature in a faster time. It came to the following.

1 is a schematic diagram showing a process of forming a diamond thin film by a conventional laser ablation method.

2 is a schematic view showing a process of forming a diamond thin film by a conventional high voltage discharge plasma CVD method.

3 is a schematic diagram showing a process of forming a diamond thin film and bulk by the Lasma mixing method according to an embodiment of the present invention.

4 is a detailed coupling diagram of a reactor designed and designed in the present invention.

* Explanation of symbols for main parts of the drawings

1: laser source 2: laser beam

3: condenser lens 4: vacuum chamber

5: Target driven motor 6: Graphite target (cathode)

7: laser plum 8: anode (substrate holder)

9: plasma zone 10: substrate heater

11: substrate 12: reactor

12a: connection connector 12b: hole for laser beam irradiation

12c: Screw hole for fixing target and reactor 12d: Screw hole for connecting cathode and lead conductor

13: hydrogen gas guide tube 14: driven reflector

In order to achieve the above object, the diamond thin film and the bulk forming method by the unique combination of the laser ablation method according to the present invention and the high voltage discharge plasma CVD method under hydrogen gas are separated at regular intervals by a high voltage supply device. A high voltage is applied to the two pure (99.999%) graphite electrodes to generate a discharge plasma inside the reactor, which turns the surrounding hydrogen gas into excited atomic hydrogen and mixes it with numerous carbon atoms emitted from the cathode, The laser beam is irradiated onto the graphite target (causwood) to cause carbon particles with high kinetic energy to protrude from the inside of the plasma toward the substrate, mixing with the atomic hydrogen inside the plasma, and depositing the mixed particles on the substrate located in the middle of the plasma. Diamond thin film or bee In the diamond thin film or bulk formation method by the laser ablation method combining the laser ablation method and the high voltage discharge plasma CVD method, in order to improve the deposition efficiency and speed by increasing the plasma density during the deposition process described above. The method may further include enclosing the plasma zone with the designed high temperature heat-treated glass reactor. At this time, to use the special guide tube to induce the hydrogen gas to be supplied near the substrate on which the diamond film is formed in order to make the above-described hydrogen atoms to effectively function on the substrate and increase the generation efficiency of atomic hydrogen, When irradiating a laser beam to a fixed target, it is preferable to use a driving reflector in order to have the same effect as the state in which the target is rotating.

Hereinafter, a diamond thin film or a bulk forming method according to a preferred embodiment of the present invention will be described in more detail with reference to the accompanying drawings.

3 is a schematic diagram illustrating a process of forming a diamond thin film or bulk by a laser mixing method combining a laser ablation method and a high voltage discharge plasma CVD method according to an embodiment of the present invention. As shown in FIG. 3, in the diamond thin film or the bulk forming method by the mixing method of the laser ablation method and the high voltage discharge plasma CVD method according to the present invention, the above two types of methods have mutual advantages and disadvantages. Glass reactors heat-treated in a plasma zone to increase thin film deposition rate, efficiency and to form high-quality diamonds when specially bonded to complement and form a thin diamond film or bulk on a substrate in a hydrogen atmosphere (see FIG. 4). And to supply hydrogen gas near the substrate where the diamond thin film is formed so that the above-described atomic hydrogen can function effectively on the substrate and increase the generation efficiency of atomic hydrogen. Using special guide tubes to guide and The diamond thin film and the bulk forming method by the unique combination method of the laser ablation method according to the present invention and the high voltage discharge plasma CVD method under hydrogen gas according to the present invention are separated by a high voltage supply device. A high voltage is supplied to the two pure graphite electrodes with a power supply to generate a discharge plasma, and the surrounding hydrogen gas is made into excited atomic hydrogen, mixed with carbon atoms emitted from the cathode, and the laser beam is Irradiates the carbon particles with high kinetic energy from the inside of the plasma toward the substrate to be mixed with the atomic hydrogen inside the plasma, and then settles on the substrate in the middle of the plasma to form a diamond thin film or bulk. Laser Ablation Methods and Classics A diamond thin film or a bulk-forming method using a mixed method of a discharge plasma CVD method.

In the present invention, to complement the above-mentioned disadvantages of the laser ablation method only, in order to increase the efficiency of the plasma CVD method under a hydrogen atmosphere, the two types of formation methods are specifically combined, and the plasma zone in the reactor located in the center of the vacuum chamber Enclosed by a glass reactor fabricated at high temperature, the density of the plasma zone is increased to improve the excitation efficiency of the hydrogen gas and the deposition rate of the thin film. When diamond is formed on an overlying substrate, the diamond thin film or bulk is produced with better quality than conventional methods. Hydrogen gas supplied by the guide tube to the vicinity of the substrate inside the reactor is decomposed from the substrate by the reaction of atomic hydrogen with carbon atoms to form the graphite phase (sp, sp ² ) by the atomic hydrogen changed in the high density plasma, As a result, only a diamond phase sp ³ of pure quality is present on the substrate 4, resulting in a diamond thin film or bulk having improved electrical, electronic, thermal, and mechanical properties. In addition, the lasma mixing method newly devised in the present invention is designed to be effectively applied to other types of thin film production, such as hard coating (for example, electronic materials, cutting tools, etc.) on any material surface. . In particular, recently, a diamond thin film manufacturing method that has gained great attention as a flat panel display device by providing a thin film that does not use the field emission tip, which is the most important in manufacturing a field emission device (FED), etc. It can be applied as

Claims (6)

Diamond thin film and bulk formation method by specially combining the laser ablation method and the advantages and disadvantages of the high voltage discharge plasma CVD method under hydrogen gas to complement each other, and between the two pure graphite electrodes spaced at regular intervals. An optical device with a driving reflector that supplies a high voltage to generate a discharge plasma to mix surrounding hydrogen gas into excited atomic hydrogen to mix with carbon atoms emitted from the cathode and to condense the laser beam from the laser source into a lens. Irradiated on a fixed plate-shaped graphite target (cathode) in a furnace vacuum chamber, to eject carbon particles (laser plumes) with high kinetic energy from the inside of the plasma toward the substrate located on the anode, thereby exciting the excited carbon inside the plasma. Mix with the atom, Diamond thin film or bulk forming method characterized by using a laser ablation method of fixing the mixed particles on a substrate located in the middle of the plasma to form a diamond thin film or bulk and a mixing method combining high voltage discharge plasma CVD . During the deposition process as set forth in claim 1, in order to make the atomic hydrogen function effectively on the substrate and to increase the generation efficiency of the atomic hydrogen from the hydrogen gas, hydrogen gas is supplied to the substrate close to the diamond thin film formation. A method and apparatus for forming a diamond film or bulk, further comprising a guide tube, which is a special device (process), for inducing to be guided. During the deposition process described in claim 1, the plasma reactor is enclosed in a high temperature heat-treated glass reactor designed to be easily replaced in the center of the chamber, thereby increasing the plasma density therein, thereby increasing the excitation efficiency and deposition rate (cost reduction). And a device (process) further to improve the diamond thin film or bulk forming method and apparatus. According to claim 1, wherein during the deposition process, when driving the laser beam from the laser source to the target, the drive-type reflector optical device that can be rotated gradually between the laser source and the target so that the effect of rotating even if the target does not rotate Diamond thin film or bulk forming method characterized in that provided with the apparatus. In the deposition process described in claim 1, the new method of combining the two types of deposition methods is the formation of a thin film which does not use the field emission tip, which is most important in the manufacture of hard coatings, FED, etc. Similarly, a thin film forming method and apparatus for thin film devices, etc., which are designed to be effectively applied to other types of thin film production. In the deposition process described in claim 1, the substrate is installed on a fixed anode which does not rotate, and has a structure in which the substrate is positioned near the center of the plasma where the temperature is high so that a separate substrate heater is not required. Diamond thin film or bulk forming method and apparatus therefor.