JPS5876140A - Chemical vapor deposition apparatus - Google Patents

Abstract

PURPOSE:To easily remove and recover a high m.p. metal adhered to a part other than an object to be treated, by providing a high m.p. metal recovering means to a vapor deposition apparatus wherein the gaseous substance of the high m.p. metal is reduced in a reaction tube and the formed high m.p. metal is adhered to the object to be treated. CONSTITUTION:This chemical vapor deposition apparatus consists of a vapor deposition circuit A and recovery circuit B. A reaction tube 1 is heated in a heating furnace 2 and an object 3 to be treated is quietly rotated horizontally to send the gaseous substances convertible to a high m.p. metal, for example, WF6 and a carrier gas such as H2 into the pipe 1 from an inflow port 1a. These gases 9 are reduced under heating in the pipe 1 and W is uniformly adhered to the desired surface of the object 3 to be treated. At this time, the part of the produced W is adhered to the inner surface of the pipe 1 as an adhered contaminant 5. In this case, when a F2 gas is sent into the tube 1, it is reacted with the contaimnant 5 to form WF6 and this WF6 is flowed into a trap 6 to be subjected to vapor deposition in the succeeding process.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a chemical vapor deposition (CVD) apparatus that is capable of removing and recovering high melting point metal deposited on the inner surface of a reaction tube.

For example, by treating W+, Mo2 with fluorine to make WFs or MoF6, a high melting point metal is once converted into a gaseous material, and the resulting high melting point metal gaseous material is sent into a reaction tube using hydrogen or the like as a carrier gas. By heating these gases in the reaction tube, etc., a reduction reaction is caused in the reaction tube, a high melting point metal is generated from the gaseous substance, and this high melting point metal is introduced into the reaction tube. Chemical vapor deposition equipment that deposits a film on the surface of a pre-housed workpiece (substrate) is widely known.

In this chemical vapor deposition apparatus, the high melting point metal produced within the reaction tube also adheres to the inner wall surface of the reaction tube and other parts other than those to be treated or buried. When these fouling deposits become large,
For example, it may peel off from the surface to which it is attached and fall onto the object to be processed, causing defects thereon or causing problems in subsequent vapor deposition operations. Therefore, when using a chemical vapor deposition apparatus, one of the important tasks is to remove this fouling deposit. Conventionally, this removal work has been carried out using mechanical methods such as honing or chemical methods such as dissolving and cleaning with H2O2, but these methods require the disassembly, assembly, and cleaning of the equipment. The work time becomes longer and the work is troublesome, as extra time is spent on removing and drying the liquid and other pre-work and post-work. Furthermore, since it is difficult or impossible to recover the removed high melting point metals, there is also the disadvantage that high melting point metals such as rare metals and expensive W and Mo are wasted.

In view of these circumstances, an object of the present invention is to provide a chemical vapor deposition apparatus that facilitates the removal and recovery of high melting point metals as contaminating deposits.

The chemical vapor deposition apparatus according to the present invention includes a reaction tube and a means for pumping a gaseous substance of a high melting point metal into the reaction tube, and removes the high melting point metal from the gaseous substance by a reduction method in the reaction tube. The high melting point metal produced is
In a chemical vapor deposition device for depositing on the surface of a workpiece housed in the reaction tube, there is provided a means for feeding into the reaction tube a gas capable of converting the high melting point metal into a gaseous material, and a high melting point generated in the reaction tube by the gas. and a means for recovering metal gaseous substances. Hereinafter, one embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a partially cutaway side view showing a reaction tube portion of a chemical vapor deposition apparatus according to the present invention, in which a vertically standing reaction tube l is equipped with a heating furnace 2 on the outside, and a workpiece 3 inside. is placed on the pedestal 4. The workpiece 3 is located approximately at the center of the heating furnace 2 . The pedestal 4 is supported by a rotating shaft 6 protruding from the lower end of the reaction tube 1 to the outside, and a drive device (not shown) rotates the rotating shaft 6 to rotate the product to be processed.
Gently rotate horizontally with the In the figure, 1a is a gas inlet, 7 is a 7-lunge, and 8 is a gas exhaust flange. Such a structure of the reaction tube portion is not essentially different from the conventional one.

While heating the reaction tube 1 in the heating furnace 2, the product 3 to be processed is gently rotated horizontally, and a gaseous substance of a refractory metal (for example, WF6) is introduced into the reaction tube 1 from the inlet 1a as a carrier gas (
For example, feed in with H2). Injected gas (
, for example, WFe+2) 9 is heated in the reaction tube 1 to cause a reduction reaction, so that a high melting point metal (eg, W) is generated from the gaseous substance and adheres to a desired surface of the workpiece 30. Since the article 3 to be treated is horizontally rotating quietly at this time, a uniform high melting point metal coating is formed on the surface to be treated. The 30 revolutions of the object to be treated also serves to stir the gas 9. Note that a part of the generated high-melting point metal also adheres to parts other than the object to be processed, such as the inner surface of the reaction tube near the object to be processed, and becomes a fouling deposit 5.

Next, a means for removing and recovering this fouling deposit will be explained. FIG. 2 is an explanatory diagram of the entire chemical vapor deposition apparatus according to the present invention. Block A is a deposition circuit, and block B is a recovery circuit. The vapor deposition circuit includes a cylinder 10 for containing a high-melting-point metal gas substance and a carrier gas cylinder 11, and the gas from each cylinder is fed into the reaction tube 1 through a valve 12. In the figure, reference numerals 13 and 14 indicate a flow meter provided in a delivery path exclusively for high-melting point metal gas, and pulses 15 and 16 indicate a flow meter and pulp provided in a delivery path exclusively used for carrier gas. The deposition circuit also includes a gas absorption device 17 and a vacuum pump 1.
8; the gas remaining in the reaction tube 1 is transferred to these devices via a valve 19.

In the figure, reference numerals 20 and 21 indicate valves respectively provided in the exhaust path dedicated to the gas absorption device and the exhaust path dedicated to the vacuum pump. The recovery circuit includes a %F2 cylinder 22 and a flow meter 23. F2 gas is fed into the reaction tube 1 through each pulp 24. The recovery circuit also includes a trap 26. which is cooled by soaking in cooling 4W 25. Atmospheric seal device 2
7 and a gas adsorption device 28, and while sealing with an atmosphere sealing device 27 so that the atmosphere does not flow into the trap 26, the high melting point metal gaseous substance generated in the reaction tube 1 is trapped in the trap 26 as described later. It is designed to be collected inside. In the figure, 29 is a pulp provided in the gaseous substance recovery path.

The removal of the fouling deposits 5 and the recovery of the high melting point metal will be explained in detail. When chemical vapor deposition is performed with the inner diameter of the reaction tube 1 being 180 m and the length of the product 3 being 30 mm, the length of the product 3 is approximately 120 mm.
Fouling deposits 5 are formed in the length range.

The amount of adhesion is determined by the amount of time and amount of production (in the case of W, it is approximately 1
It can be determined from the product of 0g7h) and the deposition time. W
For example, if the cumulative deposition time is 5 hours, the amount of deposited matter is about 50 g, and therefore the layer thickness of the fouling deposit 5 can be estimated to be about 86 μm.

The high melting point metal that is the fouling deposit is converted into a gaseous substance by, for example, being fluorinated. Between W and F, W+3Fz
Since the reaction formula -WFa is established, 3 moles of F2 are required for 1 mole of W to fluorinate W. Therefore, to fluorinate 50 g of fouling deposits, 18.3/F2 is required.

After a predetermined vapor deposition time has elapsed, the pulp 14 is closed to end the vapor deposition. However, the carrier gas H2 continues to flow. During this time, the temperature of the heating furnace 2 is maintained at 700 to 800°C, and the reducing atmosphere is maintained for at least 30 minutes. After that, the temperature of the heating furnace 2 was lowered to 300-400℃, and the pulp 16.1
2 to stop feeding F2. Next, using the vacuum pump 18, the inside of the reaction tube 1 is vacuumed at a vacuum level of 10''-2 Torr.
After that, close the pulps 19, 20 and 21, and remove the processed product 3.
2or.

The pulp 24 of the F2 cylinder 22 is gradually opened and F2 is pumped into the reaction tube 1 while rotating at a speed of 500 pm. At this time, by operating the pulp while monitoring the flow meter 23, the flow rate of F2 is adjusted to 50 cc for the first 60 minutes.
/$, and 100cc/min for the next 160 minutes.

The F2 fed into the reaction tube 1 reacts with the fouling deposits 5 attached to the inner wall surface of the reaction tube 1, and converts it into a gaseous substance.

When this reaction is completed, the removal of the fouling deposits 5 is completed.

While continuously feeding F2, the pulp 29 is opened every 60 minutes to allow the high melting point metal gas produced in the reaction tube 1 to flow into the trap 26 for 30 minutes, and then the pulp 29 is closed. The atmosphere sealing device 27 contains a sealing liquid such as trifluorochloroethylene low-polymerized oil (trade name: DAIFLOIL).
Check here whether F2 is detected 30 minutes after closing 9. This operation is repeated until the above reaction is completely completed.

WF6, which is a reaction product of F2 and W, has a freezing point of 2.3°C, so if the coolant in the cooling tank 25 is, for example, a dry ice-ethanol system (-40°C or lower), the temperature inside the trap 26 will be reduced. completely condensed and collected.

When the fluorination reaction of the high melting point metal substance as the fouling deposit is completed, F2 is detected in the atmosphere sealing device 27, so the pulps 24t and 29 are immediately closed, and at the same time, the pulp 19 is closed.
.

Excess F2 gas before this operation is adsorbed by a gas adsorption device 28 using activated carbon as an adsorbent.

In this manner, the refractory metal gaseous material collected in the trap 26 can be used as is in subsequent chemical vapor deposition operations.

The chemical vapor deposition apparatus according to the present invention has a means for sending a gas capable of converting a high melting point metal into a gaseous substance into a reaction tube, and a means for recovering a gaseous substance of a high melting point metal generated in the reaction tube by this gas. and
Fouling deposits in the reaction tube can be easily and quickly removed and immediately recovered in a form that can be reused.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway side view of a reaction tube portion of a chemical vapor deposition apparatus according to the present invention, and FIG. 2 is an overall explanatory view of the same apparatus. A... Vapor deposition circuit B... Recovery circuit 1... Reaction tube 1a... Gas inlet 2... Heating furnace 3... Product to be treated 4... pedestal 5... Contamination Adherence 6...
Rotating shaft 9...O gas 22...F2 cylinder 26...
・Trap 24.29...Pulp patent applicant Toho Metals Co., Ltd. Agent Patent attorney Hiroshi Sugawara @IWA Figure 2

Claims (1)

[Claims] (1) A reaction tube and a means for feeding a gaseous substance of a high melting point metal into the reaction tube, and a high melting point metal is generated from the gaseous substance by a reduction method in the reaction tube, and the generated high melting point metal in a chemical vapor deposition apparatus in which the substance is deposited on the surface of a workpiece housed in the reaction tube,
The reactor is characterized by comprising means for feeding a gas capable of converting the high melting point metal into a gaseous substance into the reaction tube, and means for recovering the gaseous substance of the high melting point metal generated in the reaction tube by the gas. Chemical vapor deposition equipment.