KR910007537B1 - Optical CVD System with Incandescent Light Discharge System - Google Patents

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Description

Optical CVD System with Incandescent Light Discharge System

1 is a graph showing the electron energy levels of mercury atoms.

2 is a graph showing the spectral characteristics of light emitted from a conventional mercury lamp.

3 is a block diagram illustrating an optical CVD apparatus according to the present invention.

4 is a graph showing the spectral characteristics of a mercury lamp according to the invention.

Sectional view of the mercury lamp according to the invention in figures 5a, b, c.

6 is a block diagram illustrating the lighting of several mercury lamps.

7 is a block diagram illustrating several mercury lamps connected in series.

The present invention relates to an optical CVD apparatus equipped with an incandescent light discharge system. In particular, the present invention relates to a light-increasing CVD apparatus for depositing a coating using a low pressure mercury lamp.

In general, a high pressure mercury lamp and a low pressure mercury lamp are mainly used in a light-increasing CVD apparatus. Low pressure mercury lamps consist of mercury gas and a light emitting bulb filled with argon gas of mercury torr as an initiator. The bulb is equipped with a pair of internal electrodes connected to an external terminal for power supply.

,

,

, 및

으로 여기된다.Here, when a high voltage is applied to the electrode, a discharge occurs, so that the mercury atom has various high energy levels,

,

,

, And

Is here.

의 준위를 갖는 것은 아르곤 가스와의 충돌로 인해 바닥수준 즉 기저층의 준위

로의 전이가 일어나며, 따라서 254nm 파장의 빛이 이러한 전이와 수반하여 방출된다. 이러한 종래의 수은램프의 스펙트럼 분포는 제2도에 나타나 있다. 제2도를 보면은, 방출강도가 파장 254nm에서 가장 강하며 다음으로는 185nm근처임을 알 수 있다.Most of the excited atoms

The level of is due to the impact of argon gas on the ground level or base level

Transition occurs, so light of 254 nm wavelength is emitted with this transition. The spectral distribution of this conventional mercury lamp is shown in FIG. Looking at Figure 2, it can be seen that the emission intensity is the strongest at the wavelength of 254nm and next around 185nm.

,여기서 n은 정수)를 분해반응시켜서 반도체 막을 형성하는 데에는 짧은 파장, 특히 185nm의 조사가 효과적이다. 따라서 185nm 근처의 파장에서 강화된 자외선을 얻는 것이 요구된다.However, in current open methods of forming semiconductor films by light-increasing CVD, silane gas (

Where n is an integer), a short wavelength, particularly 185 nm, is effective for forming a semiconductor film. Thus, it is desired to obtain enhanced ultraviolet light at wavelengths near 185 nm.

Furthermore, in the conventional CVD apparatus, since ultraviolet rays are irradiated to the reaction gas from the mercury lamp through the light window, when deposited on the substrate, the deposition occurs on the surface of the light window at the same time as the radiation passes through, and consequently, is deposited on the window. The reaction product forms a thick transparent layer, which greatly reduces the ultraviolet light passing through the window, and the reaction is terminated without exciting the reaction gas.

This makes it impossible to form the same film continuously after the deposition of sufficient thickness or the underlying layer.

It is an object of the present invention to provide a CVD apparatus for depositing a layer at a high rate on a substrate.

It is also an object of the present invention to provide an inexpensive optical CVD apparatus with a very small installation space.

The optical CVD apparatus according to the present invention includes a reaction chamber, a vacuum pump for a reaction chamber, a reactive gas introduction system for introducing a reactive gas into the reaction chamber, a holder for holding a substrate in the reaction chamber, a light source for the reaction chamber, and a pair of electrodes installed in the reaction chamber. And a power supply for supplying high frequency power to the light source and the electrode. This may include a matching transformer through which power is supplied to the light source and the electrode, respectively. A switch may also be included to selectively connect the power supply to one of the transformers.

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

First, FIG. 3 shows a CVD apparatus according to the present invention, which includes a reaction chamber 12, a reaction gas introduction system 16, an exhaust system 17, a holder 10 holding a substrate 11, and a light source chamber ( It consists of a mercury lamp (2) located in the light source chamber (15) and a power supply system (19).

The light source chamber 15 is provided with a light window 14, and a mesh electrode 13 is provided on the light window. The holder 10 functions as another electrode together with the substrate 11 so as to correspond to the mesh type electrode 13.

The reactant gas enters negative pressure through the system 16, which can be mixed with a dopant gas if necessary.

This reaction gas is exposed to light emitted from the mercury lamp 2 through the light window 14 made of artificial crystals. This exposure causes a photochemical reaction with the force of plasma incandescent light discharge, and as a result, the reaction product is deposited on the surface of the substrate 11. The power supply 7 can be divided using a switch 8 into mercury lamps 2 via incandescent discharge electrodes 10 and 13 and matching transformers 6 and 9.

On the other hand, after deposition of the reaction gas product is completed, the exhaust gas may be removed from the reaction chamber 12 using the discharge sheath 17.

The light source chamber 15 may be filled with nitrogen, hydrogen, or an inert gas or placed in a vacuum state. The matching transformer 6 is used to stabilize the emission in the mercury lamp despite the underload component of the mercury lamp.

The power supplied by the power supply 7 increases the intensity of light with a high frequency of 185 nm and can also be used for plasma emission in the reaction chamber 12.

The frequency range of such power is preferably 10 kHz or more, that is, 50 kHz or 13.56 MHz. As the power of such a frequency, the probability of transition to an excitation level of 6 ¹ P ₁ is set. As a result, the intensity of light increases near the wavelength of 185 nm as shown in FIG. Therefore, only the mercury lamp is contained in the light source chamber 15.

의 준위를 갖는 수은원자가 아르곤 가스와 충돌하여 254nm 의 빛을 방출한다.On the other hand, if argon gas is present in the mercury lamp 2 as in the prior art, the energy applied from the outside excites mercury, and thus mercury atoms having various energy levels exist. High probability of existence

A mercury atom with the level of collides with argon gas and emits 254 nm of light.

준위의 254nm의 발광은 이루어지지 않으므로

준위의 여기된 수은원자의 라이프 타임(life time)은 길어지게 되며, 수은이 외부전원에 의하여 갖는 에너지는 증대하고

준위를 갖는 것이 증가하여 파장 185nm의 빛이 강하게 된다. 결과적으로

수준으로의 전이가 증가될수록 퇴적 속도가 빨라지게 된다.On the other hand, if argon gas is not present in the mercury lamp as in the present invention

Since 254nm light emission is not achieved at the level

The life time of excited mercury atoms in the level will be long, and the energy of mercury from external sources will increase

Having a level increases, and the light of wavelength 185 nm becomes strong. As a result

As the transition to the level increases, the deposition rate increases.

∼

Torr 정도로 낮고 아르곤 원자가 없기 때문에 방전이 일어나기가 용이하지 않으며 매우 불안정하다.However, the vapor pressure of mercury is 25 to 50

To

As low as Torr and free of argon atoms, discharge is not easy and very unstable.

Therefore, in the present invention, high frequency power is used.

The pressure in the mercury lamp is controlled by adjusting the temperature of the mercury accumulated in the reserver 36, where mercury is condensed, from which mercury enters the mercury lamp as a vapor.

Temperature control is performed as the electric heater 35, the light is emitted in the electric heater 35 at a wavelength of 185nm containing the reserver 36 (see Fig. 4).

5a shows an example of a mercury lamp according to the present invention, which shows an example of a low pressure mercury lamp, wherein the low pressure mercury lamp 5 is composed of a bulb 21 and a pair of electrodes 3 and 3 '. It is. The bulb is filled with mercury gas and contains no argon gas.

The heater is in contact with one end of the mercury lamp.

According to this structure, the bulb becomes a fully tight quartz tube and because there is no lead wire across the wall of the tube to contact the inside of the tube, due to the difference in thermal expansion between the metal (wire) and the quartz (tube) There is no fear of crack formation.

On the other hand, when using several mercury lamps, the choke coils connected in series for each mercury lamp can be disassembled by adjusting the resistance of the crystal tube.

5b shows another example of a mercury lamp having a pair of internal electrodes 22 and 22 'to prevent ions from colliding with the inner surface of the crystal bulb 5. Here, the inner electrode is installed to face the outer electrodes 3 and 3 'with the crystal wall interposed therebetween, so that a constant and stable resistance can be obtained by a capacitor between them.

5C shows a variation of FIG. 5B, wherein the internal electrodes 22 and 22 'are separated into two parts, respectively.

In addition, the first electrodes 22-1 and 22'-1 are made of a large work function material that can withstand high temperatures, such as platinum, tungsten, molybdenum, or a compound thereof. Receive the released ions.

In addition, the second electrodes 22-2 and 22'-2 are positioned near the ends of the mercury lamp, and are made of a low work function material such as a metal electrode coated with magnesium, nickel, or barium oxide. It is made. In general, the material used in the second electrode may be damaged by ion collision.

On the other hand, the materials used in the first electrode are stable to collision of ions and their emission start voltage is very high. For this reason, the electrodes 22 and 22 'are made of two materials.

On the other hand, since the external electrode and the internal electrode are separated, their manufacture becomes very easy.

6 shows several mercury lamps 5-1, 5-2 connected in parallel with the power supply 19; , (5-n), where incandescent light emission occurs between a pair of electrodes at opposite ends of each mercury lamp. In order to convert the incandescent light discharge in each mercury lamp into an arc discharge, it is very effective to apply a high driving voltage to each mercury lamp. For example, a voltage of 25kv is applied to the mercury lamp by bringing the outer surface of the mercury lamp into contact with the electrodes 32 and 32 '. By this fixed pressure, arc discharge occurs locally. Such discharge is not extinguished even when the electrodes 32 and 32 'are removed from the mercury lamp 5-1, and spreads to the inner surface of the bulb.

This discharge occurs in other lamps by alternately applying high voltage in the same manner as above. Therefore, the resistance of some of the glass bulbs directly below the electrodes 3 and 22 must be adjusted arbitrarily.

7 shows several mercury lamps 5-1, 5-2,... Connected in parallel with the power supply 19. , (5-n), wherein the mercury lamp can be discharged by the method described in FIG.

[Experiment]

, n은 정수)를 도입시키고 수은램프(5)에서 방출되는 자외선을 사용해 윈도우(14)를 통해서 융착시킨 다음, 홀더(10)로서의 기능을 겸하는 히터(10)에 의해 강열된 기판의 표면에 무정형 실리콘 필름을 형성시킨다.In the reaction chamber 12, silane gas (

, n is an integer) and fused through the window 14 using ultraviolet rays emitted from the mercury lamp 5, and then amorphous to the surface of the substrate heated by the heater 10 functioning as a holder 10. A silicon film is formed.

The reaction gas product deposited on the window 14 is removed by plasma etching, which can be performed by operating the switch 8 to supply power to the electrodes 10 and 13. After etching, the inside of the reaction chamber is discharged as the discharge system 17 and another substrate is inserted to form a film on the substrate in the same manner as above.

The frequency of the power was 13.56 MHz, but in the experiment, the mercury lamp 5 ranged from 1 KHz to 2.54 GHz.

The experiments thus far are intended to provide a detailed description of the present invention, but the present invention is not limited thereto, and modifications may be made in the following points. In other words, instead of the electrodes 3 and 3 ', a coil (solede) can be installed around the mercury lamp 2 valve. In addition, a loading chamber may be provided near the reaction chamber to reduce the process time. In addition to the above embodiment, uv cleaning can also be performed.

Furthermore, the present invention can be applied to optical plasma CVD which can utilize light energy and ECR (Electron Cyclotron Resonance) energy. On the other hand, the mercury lamp in the present invention is a straight tube-shaped, but can be transformed into a round, spiral, comb-like, etc.

Claims (7)

A reaction chamber comprising a holder for storing and supporting a substrate, a light source for emitting light through a light window, a pair of electrodes, a vacuum pump for the reaction chamber, a gas injection system for injecting a reaction gas into the reaction chamber, and a high frequency In an optical CVD apparatus composed of a power supply for supplying power to a light source and an electrode, the light source is actually composed of a mercury lamp which is filled with only mercury gas and generates ultraviolet light enhanced near a wavelength of 185 nm by supply of high frequency power. Optical CVD apparatus, characterized in that. 2. The apparatus of claim 1, wherein the high frequency power has a frequency in the range of 10 KHz to 13.56 MHz. Reaction chamber, reaction chamber with a light window cleaning means comprising a holder for storing and supporting a substrate, a light source for preventing light rays through the light window, and a pair of electrodes in which one of the electrodes is positioned on the light window And a gas introduction system for introducing a reaction gas into the reaction chamber, a common power supply for supplying power to the light source and the cleaning means, and selectively supplying power from the power supply to one of a pair of electrodes between the light source and the optical CVD. Or means for enabling plasma etching to be performed in the reaction chamber, wherein plasma etching is generated between the electrodes to clean the light window by means of supplying power by a common power source. 4. The optical CVD apparatus of claim 3, wherein the electrode located on the light window is a conductive mesh. The optical CVD apparatus according to claim 4, wherein the other side of the electrode is the holder. 4. The optical CVD apparatus according to claim 3, wherein the light source is actually a mercury lamp filled with only mercury gas. 4. An optical CVD apparatus according to claim 3, wherein the power has a frequency ranging from 10 KHz to 13.56 MHz.

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