KR960015961B1 - Method of depositing diamond film by dc discharge of filament cathode - Google Patents
Method of depositing diamond film by dc discharge of filament cathode Download PDFInfo
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- KR960015961B1 KR960015961B1 KR1019930025529A KR930025529A KR960015961B1 KR 960015961 B1 KR960015961 B1 KR 960015961B1 KR 1019930025529 A KR1019930025529 A KR 1019930025529A KR 930025529 A KR930025529 A KR 930025529A KR 960015961 B1 KR960015961 B1 KR 960015961B1
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B32/00—Carbon; Compounds thereof
- C01B32/25—Diamond
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
- C23C16/22—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the deposition of inorganic material, other than metallic material
- C23C16/26—Deposition of carbon only
- C23C16/27—Diamond only
- C23C16/271—Diamond only using hot filaments
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
- C23C16/22—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the deposition of inorganic material, other than metallic material
- C23C16/26—Deposition of carbon only
- C23C16/27—Diamond only
- C23C16/272—Diamond only using DC, AC or RF discharges
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
- C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
- C23C16/50—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating using electric discharges
- C23C16/503—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating using electric discharges using dc or ac discharges
Abstract
Description
제1도는 다이아몬드막 합성용 직류 글로우방전 증착장치에 대한 개략구조도.1 is a schematic structural diagram of a direct current glow discharge deposition apparatus for synthesizing a diamond film.
제2도는 (a), (b)는 본 발명의 필라멘트음극 구조를 보인 사시도.2 is a perspective view showing the filament cathode structure of the present invention (a) and (b).
제3도는 필라멘트음극의 온도에 따른 직류방전 플라즈마의 형태차이를 보인 것으로,3 shows the shape difference of the DC discharge plasma according to the temperature of the filament cathode.
(a)는 음극의 온도가 낮을 때이고,(a) is when the temperature of the cathode is low,
(b)는 음극의 온도가 높을 때이다.(b) is when the temperature of the cathode is high.
* 도면의 주요부분에 대한 부호의 설명* Explanation of symbols for main parts of the drawings
1 : 반응용기 2 : 음극1: Reaction vessel 2: Cathode
3 : 양극 4 : 진공펌프3: anode 4: vacuum pump
5 : 원료가스 공급장치 7 : 음극홀더5: source gas supply device 7: cathode holder
8 : 직류전력 공급장치 9 : 기판8 DC power supply 9 substrate
PC : 양광주PC: Yanggwangju
본 발명은 고온 필라멘트음극 직류방전법을 이용한 다이아몬드막의 합성방법에 관한 것으로, 특히 음극의 형태를 비표면적이 큰 필라멘트로 하고, 이 필라멘트음극의 온도를 충분한 열전자 방출이 이루어질 정도의 고온으로 유지시켜 직류 글로우방전이 장시간에 걸쳐 안정성으로 지속되게 함으로써 수백마이크로 이상의 다이아몬드를 증착시킬 수 있도록 한 고온 필라멘트음극 직류방전에 의한 다이아몬드막 증착방법에 관한 것이다.The present invention relates to a method for synthesizing a diamond film using a high-temperature filament cathode direct current discharge method, and in particular, the form of the cathode is a filament having a large specific surface area, and the temperature of the filament cathode is maintained at a high temperature such that sufficient hot electron emission is achieved. The present invention relates to a method for depositing a diamond film by a high temperature filament cathode direct current discharge, which enables a glow discharge to be stably maintained for a long time to deposit more than a few hundred microns of diamond.
종래의 다이아몬드 합성방법중 대표적인 기상합성기술의 한 형태로 직류 글로우방전 화학증착법(DC glow discharge CVD)이 알려지고 있는데, 이 방법은 이용한 다이아몬드의 합성과정을 제1도에 도시된 바의 직류 글로우방전 화학증착장치를 참조하여 설명하면 다음과 같다.DC glow discharge chemical vapor deposition (DC glow discharge CVD) is known as one of the typical vapor synthesis techniques of the conventional diamond synthesis method. This method uses the DC glow discharge as shown in FIG. Referring to the chemical vapor deposition apparatus as follows.
진공상태의 반응용기(1) 내부에 음극(2)과 양극(3)이 일정간격을 유기한 채 상하로 대향되게 설치되며, 반응용기(1)는 용기내부를 진공상태로 유지시키기 위한 전공펌프(4)와 원료가스의 도입을 위한 원료가스 공급장치(5)가 설치되고, 음극(2)은 음극현수선(6)에 의해 음극홀더(7)에 지지되며, 음극홀더(7)측으로는 직류전력 공급장치(8)로부터 인가되는 직류전력이 공급되도록 구성되어 있다.The negative electrode 2 and the positive electrode 3 are installed in the reaction container 1 in a vacuum state so as to face up and down with a predetermined interval, and the reaction container 1 is an electric pump for maintaining the inside of the container in a vacuum state. (4) and a source gas supply device 5 for introducing the source gas, a cathode 2 is supported by the cathode holder 7 by a cathode suspension line 6, and a direct current to the cathode holder 7 side. The direct current power applied from the power supply device 8 is configured to be supplied.
이러한 직류 글로우방전 증착장치를 이용하여 양극(3)의 상부에 놓여진 기판(9)에 다이아몬드막을 합성하는 과정은, 직류전력 공급장치(9)를 통해 음극(2)과 양극(3) 사이에 전압을 가하고, 원료가스 공급장치(5)로부터 반응용기(1) 내부로 원료가스를 유입시켜 양전극(2), (3) 사이의 공간에서 플라즈마 형성시킴으로써 원료가스를 분해하여 기판(9)의 표면에 다이아몬드막의 합성이 이루지게 된다.The process of synthesizing the diamond film on the substrate 9 placed on the anode 3 using the direct current glow discharge deposition apparatus includes a voltage between the cathode 2 and the anode 3 through the DC power supply 9. Is added, the source gas is introduced into the reaction vessel 1 from the source gas supply device 5, and plasma is formed in the space between the positive electrodes 2 and 3 to decompose the source gas to the surface of the substrate 9; The diamond film is synthesized.
이때, 다이아몬드막의 증착속도를 수십 μm/h 수준으로 높게 유지시키기 위해서는 압력을 수집 torr 내외로 높게 하고 방전전류밀도로 0.5A/㎠ 이상으로 높게 하여 글로우-아크 천이 영역에서 방전을 행해야 한다(참조 : 일본특허공고 평2-133398).At this time, in order to maintain the deposition rate of the diamond film as high as several tens of μm / h, the pressure should be increased in and out of the collection torr and discharged in the glow-arc transition region with the discharge current density higher than 0.5A / cm 2. Japanese Patent Publication No. 2-133398).
이러한 고밀도 글로우방전에서는 양극(3)에 위치하는 기판(9)의 직상(直上)에 뚜렷한 발광영역이 형성되는데, 이 영역은 양광주(positive column, PC)라 불리운다. 다이아몬드는 이 양광주(PC)와 접촉한 기판(9)상에서만 증착이 이루어지게 된다.In such a high-density glow discharge, a distinct light emitting region is formed directly on the substrate 9 positioned on the anode 3, which is called a positive column (PC). Diamond is deposited only on the substrate 9 in contact with the bright column PC.
한편, 기상합성 다이아몬드막을 적외선용 광학창, 공구, 히트씽크(heat sink)등의 용도로 사용하기 위해서는 두께가 100 내지 수백마이크론 이상의 두꺼운 자유막(free-standing film)으로 하여야 하는데, 직류 글로우방전법을 이용한 다이아몬드막의 증착속도중 지금까지 보고된 바의 최대 증착속도인 20㎛/h의 증착속도하에서도 두께 1㎜의 다이아몬드막을 얻기까지는 약 50시간이 요구되고 있다.On the other hand, in order to use the vapor-composite diamond film for infrared optical windows, tools, heat sinks, etc., a thick free-standing film having a thickness of 100 to several hundred microns or more should be used. It is required about 50 hours to obtain a diamond film having a thickness of 1 mm even under a deposition rate of 20 µm / h, which is the maximum deposition rate reported so far, among the deposition rates of diamond films using.
이와같이 약 50시간이라는 긴 증착시간 동안에 걸쳐 안정적인 증착공정이 이루어지기 위해서는 플라즈마가 불안정하여 소실(extinguish)되거나 방전전류가 크게 약화되지 않고 안정적으로 유지되어야만이 가능하다.Thus, in order to achieve a stable deposition process over a long deposition time of about 50 hours, the plasma is unstable and extinguish, or the discharge current is not significantly weakened.
그러나, 상기 고밀도 글로우방전에서도 음극과 기판간에 불규칙하고 돌발적으로 아크가 발생하여 양광주가 소실됨으로 인해 장시간의 안정적인 증착이 현실적으로 뷸가능하다는 문제점이 있다.However, even in the high-density glow discharge, there is a problem that a stable deposition for a long time is possible because the arc is generated irregularly and unexpectedly between the cathode and the substrate, and thus loses the positive liquor.
또한, 고밀도 직류 글로우방전시에 음극은 방전에 의해 형성된 이온충격에 의해 고온으로 가열될 수 있는데, 기존의 음극형태는 봉(rod), 판(plate) 또는 관(tube) 등의 비표면적 작은 형상을 취함에 따라 합성조건에 탄화에 따른 부피팽창에 의하여 탄화가 이루어진 층이 미처 탄화가 이루어지지 않은 부위로부터 박리(spalling)되거나 균열(cracking)이 발생하여 합성도중에 아크가 유발됨에 따라 방전이 소실되는 현상이 초래된다.In addition, during high-density direct current glow discharge, the cathode may be heated to a high temperature by the ion bombardment formed by the discharge. The conventional cathode type has a small specific surface area such as a rod, plate, or tube. When the carbonized layer is spalled or cracked from the uncarbonized part due to the volume expansion due to carbonization in the synthesis conditions, the discharge is lost as the arc is generated during the synthesis. The phenomenon is brought about.
이러한 아크발생에 의한 방전손실의 이유는 합성중 음극의 탄화층이 박리되어 음극몸체로부터 떨어져 나오는 순간에 그 부위의 전기장에 급격한 변화가 야기되거나, 균열부위에 생성된 예리한 모서리가 전기장의 집중을 유발하기 때문인 것으로 판단된다.The reason for the discharge loss due to the arc generation is that a sudden change in the electric field of the site occurs at the moment when the carbonized layer of the cathode is separated and separated from the cathode body during synthesis, or the sharp edges generated at the cracks cause the concentration of the electric field. It is because it is.
관이나 판형태의 경우 두께를 얇게 하여 비표면적을 증대시킴에 의해 탄화가 균일하게 이루어지도록 하게되면 박리현상의 발생을 억제할 수도 있기는 하나, 일단 탄화된 음극을 재사용하는 경우 승온과정에서 열충격에 의한 균열 및 파괴가 발생하여 역시 아크가 유발되는 문제점이 그대로 남게 된다.In the case of tube or plate shape, carbonization can be suppressed by making the carbonization uniform by increasing the specific surface area by thinning the thickness, but once the carbonized cathode is reused, Cracks and fractures caused by the arc also remains the problem that causes the arc.
종래의 직류 글로우방전법에 의한 다이아몬드 합성시에 나타나는 또 하나의 문제점은, 부도체인 다이아몬드막이 기판위로 피복되어 그막의 두께가 증착됨에 따라 점차 방전이 약화되고 증착속도가 감소하여 약 100마이크론 이상의 두꺼운 다이아몬드막의 증착이 불가능하다는 점이다.Another problem that occurs in the diamond synthesis by the conventional direct current glow discharge method is that as the non-conductive diamond film is coated on the substrate and the thickness of the film is deposited, the discharge is gradually weakened and the deposition rate decreases, resulting in a thick diamond of about 100 microns or more. The deposition of the film is impossible.
이와같은 문제점을 해결하기 위해 일본공개특허 평3-142104호에서는 다이아몬드막에 붕소를 도핑하여 전도성을 부여한 방법이 알려지고 있긴 하나, 이 방법은 도핑된 붕소가 합성된 다이아몬드막의 특성을 크게 제한하는 단점을 지니고 있다.In order to solve this problem, Japanese Laid-Open Patent Publication No. 3-142104 discloses a method of imparting conductivity by doping boron to a diamond film, but this method greatly limits the characteristics of the diamond film synthesized with doped boron. It has
따라서, 본 발명은 종래의 직류 글로우방전 증착법에 의한 다이아몬드 합성법이 지니고 있는 상기의 제반 문제점을 해결하기 위한 것으로, 음극을 비표면적이 큰 필라멘트로 하고, 이 필라멘트음극의 온도를 충분한 열전자 방출이 일어날 정도의 고온으로 유지시켜 높은 속도로 수백마이크론 이상의 두께를 갖는 다이몬드막을 합성할 수 있도록 한 고온 필라메트음극 직류방전에 의한 다이아몬드막 증착방법을 제공하는데 발명의 목적을 두고 있다.Accordingly, the present invention is to solve the above problems of the diamond synthesis method by the conventional direct current glow discharge deposition method, the cathode is a filament with a large specific surface area, the temperature of the filament cathode is enough to cause a hot electron emission SUMMARY OF THE INVENTION An object of the present invention is to provide a method for depositing a diamond film by a high temperature filament cathode direct current discharge, which is capable of synthesizing a diamond film having a thickness of several hundred microns or more at a high rate by maintaining a high temperature.
본 발명의 직류 글로우방전을 수십시간 이상 안정하게 유지되도록 함으로써, 직경 10㎜ 이상의 면적에 증착속도 10∼30㎛/h 이상의 높은 속도로 두께 수백 ㎛ 내지 1㎜ 이상의 다이아몬드 막을 이종 기판상에 합성할 수 있다.By maintaining the DC glow discharge of the present invention stably for several tens of hours or more, a diamond film of several hundreds of micrometers to 1mm or more in thickness at a deposition rate of 10 to 30 µm / h or more in an area of 10 mm or more in diameter can be synthesized on a heterogeneous substrate. have.
본 발명의 다이아몬드막 증착법에서는 직류 글로우방전의 기판 단위면적당 소모전력을 1.5∼2KW/㎠ 내외로 하여, 15∼25㎛/h 이상의 높은 증착속도로 두께 수백 ㎛∼1㎜ 이상의 다이아몬드 후막을 합성할 수 있다.In the diamond film deposition method of the present invention, the power consumption per unit area of the DC glow discharge is about 1.5 to 2 kW / cm 2, and a diamond thick film having a thickness of several hundred μm to 1 mm or more can be synthesized at a high deposition rate of 15 to 25 μm / h or more. have.
본 발명의 음극의 형태를 종래의 음극에 비해 비표면적이 월등히 큰 나선 필라멘트(sprial filament)로 함으로써 탄화가 균일하게 이루어지도록 함과 아울러 박리 및 균열의 발생을 억제하여 아크를 방지한데에 기술적 특징이 있다.The shape of the negative electrode of the present invention is made of a spiral filament having a much larger specific surface area than that of a conventional negative electrode, thereby making carbonization uniform and suppressing the occurrence of peeling and cracking, thereby preventing the arc. have.
특히, 본 발명의 필라멘트음극의 탄화에는 별도의 장비를 사용하지 않고 처음 사용하려는 음극구조물을 음극에 장착한 후 가스압력, 가스조정, 전압, 전류, 및 음극온도를 다이아몬드 합성을 위한 증착조건과 유사한 범위에서 수시간동안 유지시키는 것에 의해 간단하게 탄화가 완료된다.In particular, the carbonization of the filament cathode of the present invention is equipped with a cathode structure to be used for the first time without using any equipment, and the gas pressure, gas adjustment, voltage, current, and cathode temperature are similar to the deposition conditions for diamond synthesis. The carbonization is simply completed by keeping for several hours in the range.
이와같은 필라멘트의 재질은 탄탈륨이나 텅스텐등의 고융점 금속이 바람직하며, 필라멘트 도선의 직경은 0.1∼1㎜ 정도가 적절하고 필라멘트는 나선직경은 증착면적에 따라 임의로 변화가 가능하다.The material of the filament is preferably a high melting point metal such as tantalum or tungsten. The diameter of the filament wire is preferably about 0.1 to 1 mm, and the filament can be arbitrarily changed according to the deposition area.
다음, 본 발명에서는 상기 필라멘트음극을 지지함에 있어서 제2도의 (a), (b)에 도시된 바와 같이 나선필라멘트(10) 전체를 고융점 금속선(wire)으로 이루어진 필라멘트 지지선(11)을 사용하여 음극홀더에 걸어 넣거나 매달아 구조를 취하고 있다는데에 특징이 있다.Next, in the present invention, as shown in (a) and (b) of FIG. 2, the filament support line 11 made of a high melting point metal wire is used to support the filament cathode. It is characterized by being structured by hanging or hanging on the cathode holder.
만일, 필라덴트의 양단만을 고정하게 되면 고온에서 탄화가 이루어짐에 따라 필라멘트가 불균일하게 뒤틀리고 변형되어 양광주가 균일하고 대칭적으로 형성되지 못하게 된다. 따라서 본 발명에서는 상기한 바의 나선 필라멘트(10)를 금속선으로 구성된 필라멘트 지지선(11)으로 걸거나 매다는 형태를 취함으로써 나선 필라멘트(10)가 고정되지 않고 지지선에 매달린 상태에서 자유롭게 움직일 수 있으므로 탄화시의 부피팽창을 제약없이 수용할 수 있게 되어 필라멘트의 뒤틀림이나 변형이 방지된다.If only both ends of the filaments are fixed, the filaments are unevenly distorted and deformed as carbonization is performed at a high temperature, thereby preventing the bright wine from being formed uniformly and symmetrically. Therefore, in the present invention, by taking the form of hanging or hanging the filament support line 11 composed of metal wires as described above, the spiral filament 10 can move freely in a state where it is not fixed and suspended on the support line. It is possible to accommodate the expansion of the volume without restriction to prevent distortion or deformation of the filament.
그리고, 본 발명의 방법은 필라멘트음극의 온도를 충분한 열전자 방출이 이루어질 정도로 고온으로 유지하여 방전전류량을 증가시켜 방전을 안정화함에 또 다른 기술적 특징이 있다.In addition, the method of the present invention has another technical feature of stabilizing the discharge by maintaining the temperature of the filament cathode at a high temperature such that sufficient hot electron emission is achieved to increase the amount of discharge current.
이와같이 음극의 온도를 열전자 방출이 충분하게 이루어질 정도로 높이게 되면 다이아몬드막의 두께가 1㎜ 이상으로 두꺼워져도 방전이 약화되지 않고 안정하게 유지된다.In this way, when the temperature of the cathode is increased to a sufficient degree of hot electron emission, even if the thickness of the diamond film becomes thicker than 1 mm, the discharge is not weakened and remains stable.
만일 음극의 온도가 열전자 방출이 일어나지 않을 만큼 낮은 경우에는 기판에 다이아몬드막이 피복되어 그 두께가 두꺼워짐에 따라 방전전류가 점차 감소되고 방전이 약화되는 현상이 관찰되는데, 이때의 플라즈마 발생양상은 제3도의 (a)와 같다.If the temperature of the cathode is low enough that no hot electron emission occurs, as the diamond film is coated on the substrate and the thickness thereof becomes thicker, the discharge current is gradually decreased and the discharge is weakened. Same as (a) of FIG.
즉, 양광주(PC)가 음극 필라멘트(10)와 기판(9) 사이의 공간을 다 채우지 못하고 음극 필라멘트(10)와 플라즈마 기둥 상단간에 일정한 거리를 유지한다.That is, the positive column PC does not fill the space between the cathode filament 10 and the substrate 9 and maintains a constant distance between the cathode filament 10 and the top of the plasma column.
이러한 때에는 다이아몬드막의 두께가 두꺼워짐에 따라 점차로 방전전류가 약화되고 증착속도가 감소된다.In this case, as the diamond film becomes thicker, the discharge current gradually decreases and the deposition rate decreases.
그러나, 음극의 온도가 고온으로 유지되어 열전자 방출이 충분할 때에는 제3도의 (b)에서와 같이 양광주(PC)가 음극 필라멘트(10)와 기판(9) 사이의 공간 전체를 채우며, 플라즈마 기둥 상단부가 음극과 접촉한 상태를 유지하게 된다.However, when the temperature of the cathode is maintained at a high temperature and the hot electron emission is sufficient, the positive column PC fills the entire space between the cathode filament 10 and the substrate 9 as shown in FIG. Maintains contact with the cathode.
이때에는 다이아몬드막의 두께가 1㎜ 이상으로 두꺼워지더라도 방전전류의 감소나 증착속도의 감소현상이 발생되지 않는다.At this time, even if the thickness of the diamond film becomes thicker than 1 mm, the reduction of the discharge current or the deposition rate does not occur.
본 발명의 필라멘트음극은 별도의 가열수단없이도 직류방전에서 발생되는 이온의 충전에 의해 원하는 온도까지 가열될 수 있다.The filament cathode of the present invention can be heated to a desired temperature by charging of ions generated in direct current discharge without a separate heating means.
한편, 종래의 열필라멘트 화학증착법(hot filament CVD)에서 필라멘트와 기판간에 직류바이어스(dcbias)를 거는 EACVD 방법에서는 필라멘트를 별도의 전원을 사용하여 통전 가열하는데, 이때 바이어스 전압은 300V 이하이고 전류량은 수십 mA이하이다.On the other hand, in the conventional hot filament CVD (EACVD) method of applying a direct current bias (dcbias) between the filament and the substrate, the electric current is heated by using a separate power source, the bias voltage is 300V or less, the amount of current is several tens It is below mA.
따라서 본 발명의 필라멘트음극의 가열방법은 기존의 EACVD 방법과는 전혀 다른 개념의 방법이다.Therefore, the heating method of the filament cathode of the present invention is a concept of a completely different concept from the existing EACVD method.
본 발명의 방법에 의해 제조된 다이아몬드막은 라만(Raman)분석결과 비(非)다이아몬드상이 없고, FWHM[(Full Width at Half Maximum)치가 3내외이며, 두께 1㎜내외로 두껍게 증착된 상태(표면을 연마하지 않은 상태)에서도 반투명한(transluscent) 우수한 합성상태를 나타낸다.The diamond film produced by the method of the present invention has a Raman analysis and has no non-diamond phase, and has a FWHM ((Full Width at Half Maximum) value of about 3 and a thickness of about 1 mm thick. Unpolished) shows a good transluscent synthetic state.
상술된 본 발명의 다이아몬드막 증착방법에 대한 구체적인 공정과 다이아몬드막의 제반특성은 다음의 실시예를 통하여 보다 명확하게 이해될 것이다.Specific processes and general characteristics of the diamond film deposition method of the present invention described above will be more clearly understood through the following examples.
[실시예 1]Example 1
음극의 형태를 직경 5∼20㎜, 두께 2㎜∼50㎜의 판 및 붕으로 하고, 그 재질을 텅스텐 및 탄탈륨으로 하며, 음극온도, 전류, 가스압, 유량을 각각 2000℃, 2.7A, 200torr, 150sccm으로 하고, 3% 메탄-l% 산소-수소혼합가스를 원료가스로 사용하여 다이아몬드 합성을 시도하였다. 그 결과, 합성중에 음극의 탄화가 진행되면서 탄화층이 불규칙하게 떨어져 나오며 이때 생성된 예리한 모서리에서 아크가 발생하여 양광주가 소실됨으로써 수시간 이상의 안정한 합성이 불가능하였다.The shape of the cathode is 5-20 mm in diameter and 2 mm to 50 mm thick, and the material is tungsten and tantalum, and the cathode temperature, current, gas pressure and flow rate are 2000 ° C., 2.7 A, 200 torr, At 150 sccm, diamond synthesis was attempted using 3% methane-l% oxygen-hydrogen mixed gas as the source gas. As a result, as the carbonization of the cathode progressed during the synthesis, the carbonized layer was irregularly dropped, and arcing occurred at the sharp edges generated at this time, resulting in the loss of the bright wine.
그러나, 도선굵기 0.5㎜, 필라멘트 외경 6㎜의 탄탈륨제 필라멘트를 음극으로 사용한 경우에는 동일한 합성조건에서 합성중의 음극의 온도를 2300℃로 유지하여도 박리나 균열등이 발생하지 않고, 아크발생이 완전히 방되며 수십∼100시간 이상 안정한 증착이 이루어졌다.However, when tantalum filaments having a wire thickness of 0.5 mm and a filament outer diameter of 6 mm were used as the cathode, even if the temperature of the cathode during synthesis was maintained at 2300 ° C., no peeling or cracking occurred, and arcing was not generated. Full deposition and stable deposition over several tens to 100 hours were achieved.
[실시예 2]Example 2
탄탈륨제 필라멘트를 음극으로 사용하고, 전류, 가스압, 유량을 각각 2.7A, 200torr, 150sccm으로 하고 3%메탄-l% 산소-수소혼합가스를 원료가스로 사용하여 다이아몬드 합성을 시도하였다. 그 결과 다이아몬드막이 피복됨에 따라 점차로 방전전류가 약화되어 증착속도가 감소하여 100∼200마이크론 이상의 두꺼운 다이아몬드막의 합성이 불가능하였다.Diamond synthesis was attempted using tantalum filaments as cathodes, current, gas pressure, and flow rates of 2.7 A, 200 torr and 150 sccm, respectively, and 3% methane-l% oxygen-hydrogen mixed gas as the source gas. As a result, as the diamond film was coated, the discharge current gradually weakened and the deposition rate decreased, making it impossible to synthesize a thick diamond film of 100 to 200 microns or more.
그러나, 음극의 온도를 2200℃로 유지하여 열전자 방출을 증가시킨 경우에는 기판상에 다이아몬드막을 피복하여 그 두께가 약 수 백 ㎛∼1.5㎜ 내외가 되어도 방전전류가 차단되어 방전이 소실되는 현상은 발생하지 않았고, 방전이 안정하게 유지되도록 이때 증차속도는 기판온도에 따라 시간당 약 15∼25㎛ 수준을 유지하였다.However, when the temperature of the cathode is maintained at 2200 ° C. to increase the hot electron emission, a phenomenon occurs in which the discharge current is interrupted and the discharge is lost even when the diamond film is coated on the substrate and the thickness is about several hundred μm to 1.5 mm. At this time, the increase rate was maintained at about 15 to 25㎛ per hour depending on the substrate temperature so that the discharge is kept stable.
합성된 다이아몬드막 표면은 뚜렷한 다이아몬드 이외의 피크(peak)가 관찰되지 않았으며 웨이브 넘버(wave number) l334㎝-1근처에서 FWHM(Full Width at Half Maximum)이 3내외이고, 두께가 수백 ㎛-l.5㎜ 내외일때, 증착된 상태 그대로(최대한 결정립들이 노출되어 있는 막의 상단막을 연마하지 않은 상태를 지칭함) 관찰하여도 가시광선을 투과하는(반투명한) 우수한 특성을 나타내었다.On the surface of the synthesized diamond film, no peak other than diamond was observed, and the full width at half maximum (FWHM) was around 3 at a wave number of l334 cm -1 , and the thickness was several hundred μm-l. In the case of around .5 mm, even when observed in the deposited state (referring to the state that the top film of the film where the maximum grains are exposed) was not polished, it showed excellent characteristics of transmitting visible light (transparent).
[실시예 3]Example 3
필라멘트를 양단에서 고정하는 경우는 탄화 후 심하게 뒤틀려서 양광주가 균일하게 대칭적 형상으로 형성되지 못하여 다이아몬드막의 증착이 불균일하였다. 그러나 제2도와 같은 방법으로 지지하는 경우는 뒤틀림이 발생하지 아니하고 장시간 동안 양광주가 균일하게 대칭적으로 형성되었다.In the case where the filaments were fixed at both ends, the carbon film was severely twisted after carbonization, so that the bright column was not uniformly formed in a symmetrical shape, resulting in uneven deposition of the diamond film. However, in the case of supporting in the same manner as in FIG.
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