KR900000757B1 - Gas supply system of a chemical vapour deposition in a low pressure for a refractory metal - Google Patents

Abstract

A gas supply system for chemical vapour deposition under low pressure is used for depositing W and WSi2 on Si and GaAs base in process of semiconductor material manufacturing and gives a precise and safe way for the growth of film. The system has advantages of precise gas flow control by locating hydraulic valve for gas supply time control before mass-flow controller; safety; and easy maintenance of mass- flow controller by installing N2 inlet line, by-pass line, exhaust line, valves and heating tape.

Description

Gas supply system of low pressure chemical vapor deposition apparatus for refractory metal

1a, b, and c is a relationship passage and flow time curve diagram showing a state where a pneumatic valve is installed around a conventional mass flow regulator.

Figure 2a, b is a relationship and flow time curve diagram showing a state in which the pneumatic valve is installed around the mass flow regulator of the present invention.

Figure 3 is a relationship diagram showing a gas supply system of the present invention low pressure chemical vapor deposition apparatus for a refractory metal.

4A and 4B show the relationship between tungsten fluoride (WF ₆ ) and silane (SiH ₄ ) lines used in the present invention.

5 is a relationship diagram showing a countermeasure and a reactor selection function in case of power failure in the present invention.

* Explanation of symbols for the main parts of the drawings

1: main pipe 5: mass flow controller

2, 3, 4: Pneumatic valve for reactor selection 6, 22: Pneumatic valve

7: pressure switch 8, 18: check valve

9: spare line connection stage 10, 19, 20, 21: manual valve

11: bulkhead union 12: bellows

13: bypass line 14: heating tape

15: pneumatic valve (normally open)

16: Manual valve (for opening / closing and flow control)

17 solenoid valve 23 branch pipe

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas supply system of a low pressure chemical vapor deposition apparatus for depositing refractory metals in the manufacture of semiconductor devices, and in particular, silicon (Si), gallium arsenide (GaAs) substrates, and tungsten (W) and tungsten silicide ( A gas supply system for a low pressure chemical vapor deposition apparatus that enables the growth of WSi ₂ ) accurately and safely.

In general, as a method of forming a thin film required in a semiconductor process, the chemical vapor deposition method is most recently used. This is a method of depositing a solid material on a substrate by transferring a reaction gas to a reactor through a gas supply system and generating a chemical reaction.

At this time, most of the process gases used are toxic gases, and since the required thickness of the thin film is about 1 μm, special measures are required when constructing the gas supply system. However, in the conventional gas supply apparatus, as shown in FIG. 1A, the flow rate fluctuates greatly with time without considering the characteristics of the flow control.

In addition, in the case of FIG. 1B, the number of control terminals is doubled because the gas remains and the pneumatic valve is located back and forth. In addition, even though the reaction gases tungsten fluoride (WB ₆ ) and silane (SiH ₄ ) are toxic gases, Nitrogen (N ₂ ) is simply connected to the upper part of the mass flow regulator so that it can be flowed in, so that the sensor part in the mass flow controller is blocked, the O-ring of the sealing part, or the seat part of the control valve are corroded, so that the flow rate cannot be adjusted correctly or the gas leaks Had problems such as being.

In order to solve the above problems, as shown in FIG. 2A, a pneumatic valve for controlling the injection time of gas on the gas line is installed in front of the mass flow regulator, and the automobile shut-off type ensures a reliable sealing of the control valve of the mass flow regulator. By selecting to obtain the response of FIG. 2b, it is possible to accurately grow the minimum change in the structure of the thin film due to the initial flow rate change during deposition of the tungsten (W) and tungsten silicide (WSi ₂ ) thin films. When explaining the present invention in detail as follows.

As shown in FIG. 3, tungsten fluoride (WF ₆ ), hydrogen (H ₂ ), silane (SiH ₄ ), nitrogen (N ₂ ), argon (Ar), and lines are passed through the mass flow regulator (5). 1) and the main pipe (1) is passed through a heating tape (14) to the tungsten silicide (WSi ₂ ) reactor, exhaust system, tungsten (W) reactor of the low pressure chemical vapor deposition apparatus for refractory metals In the gas supply system, the tungsten fluoride (WF ₆ ), silane (SiH ₄ ), hydrogen (H ₂ ), argon (Ar), and nitrogen (N ₂ ) lines include a manual valve (10) and a bulkhead union (11). And a pneumatic valve (6) to be connected to the mass flow regulator (5), but a check valve (8) is installed on the tungsten fluoride (WF ₆ ), silane (SiH ₄ ), and hydrogen (H ₂ ) lines. Tungsten (WF ₆ ) and silane (SiH ₄ ) lines include check valves 18, manual valves 19, 20, 21, and pneumatic valves that check nitrogen (N ₂ ) flowing from the nitrogen (N ₂ ) line. Install the valve 22, the nitrogen The (N ₂ ) line is provided with a pneumatic valve (15), which is normally open, and a manual valve (16) for opening and closing and direct control, and connected to the branch pipe (23) in front of the reactor selection valve (2) and (3). In addition, a pressure switch 7 is installed on the nitrogen (N ₂ ) and the air line, and a solenoid valve 17 in two directions is installed on the air line and installed on each of the pneumatic valves. The operation and effect of the present invention configured as described above is made as follows.

In the relationship diagram shown in FIG. 3, the following chemical reaction equation is used.

2WF ₆ (g) + 3Si (s) 2W (s) + 3SiF ₄ (g)

WF6 (g) + 3H ₂ (g) W (s) + 6HF (g)

SiH ₄ (g) Si (s) + 2H ₂ (g)

W (s) + 2Si (s) WSi2 (s)

Therefore, tungsten fluoride (WF ₆ ) and hydrogen (H ₂ ) silane (SiH ₄ ) are used as the source of deposition material, and nitrogen (N 2) and argon (Ar) are used to clean the reactor, dilute the reaction gas, or promote mass transfer. Supply line is connected to the main pipe (1), and these gases are passed through the main pipe (1) and through the heating tape (14) to the reactor selection valves (2) (3) (4), where the specific process Tungsten (W) and tungsten silicide (WSi ₂ ) reactors are selected accordingly.

Air is supplied to the cylinder of the pneumatic valve 6 located in front of the mass flow regulator 5 through solenoid valves 17 in the third and second directions, thereby adjusting the injection time of each gas and controlling the sequence. can do.

In addition, the nitrogen (N ₂ ) and air lines are equipped with a pressure switch (7) to sense the supply pressure and the tungsten fluoride (WF ₆ ), silane (SiH ₄ ), and hydrogen (H ₂ ) lines, which are toxic gases. The check valve 8 is installed to prevent backflow.

Using reactor selector valves (2), (3) and (4), tungsten (W) and tungsten silicide (WSi ₂ ) deposition processes can be carried out in one reactor. It may be.

The extra line connecting end 9 capable of connecting the extra line is used for the purpose of dry etching the reactor. If you want to maintain and repair the entire gas supply system, shut off the manual valve (10) and remove both ends of the bulkhead union (11), the device is completely isolated from the entire device can be easily maintained and maintained.

The fourth turning the manual valve (19) to complement the tungsten hexafluoride (WF ₆₎ and silane (SiH ₄₎ of claim 4a degrees silane as gwange Tongdo the line (SiH ₄₎ in the case of a line, a mass flow controller (5) according to the present invention; (20) and the pneumatic valve (6) can be completely exhausted through the bypass line (13) while diluting silane (SiH ₄ ) with nitrogen (N ₂ ) and then the mass flow regulator (5) can be separated and repaired. .

In this case, assuming that nitrogen (N ₂ ) and silane (SiH ₄ ) are instantaneously mixed, nitrogen (N ₂ ) inflow time may be determined by the following equation.

Where t is nitrogen (N ₂ ), inflow time, V _p : volume of washing site, Q: flow rate of nitrogen (N ₂ ) gas, C ₀ : initial silane (SiH ₄ ) concentration, C _t : silane after time (SiH ₄ ) concentration

In the case of the tungsten fluoride (WF ₆ ) line of FIG. 4b, since the tungsten fluoride (WF ₆ ) is corrosive, no residual gas remains in the mass flow regulator 5 after the tungsten (W) and tungsten silicide (WSi ₂ ) deposition is completed. It should not be. For this purpose, immediately after the end of the process, the industrial valve 6 is shut off and the pneumatic valve 22 is opened to clean the mass flow regulator 5 with nitrogen (N ₂ ). In the case of discharging the tungsten fluoride (WF ₆ ) gas in the upper part of the pneumatic valve 6 for the purpose of maintenance and repair, the exhaust gas is directly discharged to the exhaust system through the manual valve 21 so as not to contaminate the reactor.

In addition, the tungsten fluoride (WF6) has a boiling point (17.1 ° C), which is a normal temperature range.If the temperature of the pipe is not properly adjusted, the tungsten fluoride (WF ₆ ) in the liquid state that is more corrosive than the gas in the system or fluctuates Condensation may cause corrosion. At this time, the pressure of tungsten fluoride (WF ₆ ) can be obtained in the following form using the Viral equation, which is a kind of the state equation of the actual gas.

Here, P: pressure of the tungsten hexafluoride _{(WF 6) (atm),} T: temperature of a tungsten hexafluoride _{(WF 6) (C +273.15)} , V: volume tungsten hexafluoride (C㎥) of (WF ₆₎ line, n : Mole, B: secondary vireal coefficient (Cm 3 / mol)

Moreover, the temperature of the heating tape 14 which heats the tungsten fluoride (WF6) line is maintained at 40 degreeC or more in consideration of the input fall at the time of the mass flow regulator 5 passing. When the power is cut off during the above process, as shown in FIG. 5, all the pneumatic valves except the pneumatic valve 15 in the normally open state (N.0) located in the nitrogen (N2) line are shut off and the pneumatic valve ( Only through 15) nitrogen (N ₂ ) is introduced into the reactor to force the discharge of toxic gases into the exhaust system. At this time, the toxic gas filled in the gas supply system is completely isolated from the outside because the pneumatic valve (2) (3) (4) for the reactor selection is kept in a safe state. However, when the driving part is attached to the reactor, the toxic gas may leak to parts other than the exhaust system due to the countermeasure at the time of power failure. In this case, if the manual valve 16 for opening / closing and flow rate control, located at the rear of the pneumatic valve 15, is blocked in advance, the state is maintained before the power is cut off. After the deposition process, the pneumatic valves (2) and (3) are shut off to completely separate the residual gas from the reactor, and the pneumatic valve (4) is opened and discharged directly to the exhaust system, so that the thin film can be accurately grown to a desired thickness.

As described above, the present invention provides a gas supply system of a low pressure chemical vapor deposition apparatus for depositing tungsten (W) and tungsten silicide (WSi ₂ ) on silicon (Si) and potassium arsenide (GaAs) substrates in semiconductor device fabrication. The configuration as shown in FIG. 3 provides a way to grow the film accurately and safely, and in particular, by placing the pneumatic valve for gas injection time adjustment in front of the mass flow controller, the flow rate can be precisely adjusted, and tungsten fluoride ( WF ₆₎ and silane (SiH ₄₎ N ₂ inlet line on the line, the bypass line, the exhaust line, check valve, pneumatic valve, maintenance of the mass flow controller to install a heating tape, a simplified maintenance and having a safety measure I'm letting you.

In addition, the nitrogen (N ₂ ) line is equipped with a normally open pneumatic valve and a manual valve for both opening and closing and flow control, and by placing the valves for reactor selection at the end of the main pipe, the gas supply system It can be isolated and discharged into the exhaust system, and the thin film can be accurately grown and deposited to a desired thickness and can provide the advantage of minimizing contamination between processes.

Claims (5)

Tungsten fluoride (WF ₆ ), hydrogen (H ₂ ), silane (SiH ₄ ), nitrogen (N ₂ ), argon (Ar) gas lines are connected to the main pipe 1 through the mass flow regulator 5 and the main pipe ( 1) is a tungsten fluoride gas supply system of a low pressure compounding vapor deposition apparatus for refractory metals which is discharged to a tungsten silicide (WSi ₂ ) reactor, an exhaust system, and a tungsten (W) reactor via a heating tape 14. (WF ₆ ), Silane (SiH ₄ ), Hydrogen (H ₂ ), Argon (Ar), Nitrogen (N ₂ ) lines by installing a manual valve (10), bulkhead union (11) and pneumatic valve (6) It is connected to the mass flow regulator (5), the tungsten fluoride (WF ₆ ), silane (SiH ₄ ), hydrogen (H ₂ ) check valve (8) and manual valve (19) (20) (21), bypass line (13), and a pressure switch (7), a pneumatic valve (15), a manual valve (16), and a bulkhead union (11) are installed in the nitrogen (N ₂ ) line, and the reactor selection valve (2) (3 Tungsten fluoride (WF ₆₎ The gas supply system of the refractory metal low pressure chemical vapor deposition apparatus, characterized in that the heating tape (14) and the bellows (12) is connected to the line from the line to each reactor to grow the film accurately and safely. The gas supply agent of the low pressure chemical vapor deposition apparatus for refractory metals of Claim 1 in which the pneumatic valve (6) is provided in front of each mass flow regulator (5) so that a flow volume can be adjusted correctly. According to claim 1, wherein the tungsten hexafluoride (WF _6), silane (SiH _4), nitrogen in the line (N ₂₎ inlet line, the bypass line 13, the exhaust line, pneumatic valve 22, a check valve (18 ), Manual valves (19), (20), (21) and heating tape (14) to facilitate the maintenance of the mass flow regulator (5) and to provide a safety measure, characterized in that the low pressure for refractory metals Gas supply system for chemical vapor deposition equipment. The reactor selection valve (2) (3) (4) according to claim 1, wherein the pneumatic valve (15), the manual valve (16), and the reactor selection valves (2) (3) (4) in the normally open state are installed on the nitrogen (N ₂ ) line. A gas supply system for a low pressure chemical vapor deposition apparatus for refractory metals, characterized in that the reactor is automatically washed when the power is shut off and the residual gas is isolated from the reactor. The low pressure for refractory metals according to claim 1, wherein reactor selector valves (2) (3) (4) are installed to minimize contamination between tungsten (W) and tungsten silicide (WSi ₂ ) processes. Gas supply system for chemical vapor deposition equipment.

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