Amorphous carbon film forming method and device
An amorphous carbon film forming apparatus according to the present invention is characterized by being provided with a film forming furnace 11 ; plural workpiece fixtures 23 for supporting plural plate-like workpieces 22 in a state that the same are piled up vertically in parallel with the interval between facing surfaces of two vertically adjoining of the plate-like workpieces 22 being in a range of 2 to 30 millimeters, the plural workpiece fixtures 23 being arranged within the film forming furnace 11 at a regular angular interval on a circle and being connected to a negative electrode; nozzles 31, 32 provided for supplying a processing gas and including at least one nozzle arranged at a center of the circle on which the plural workpiece fixtures 23 are arranged and plural nozzles arranged at a regular angular interval on another circle which surrounds the workpieces fixtures 23 radially outside thereof; and a plasma power supply connected to at least the workpiece fixtures 23 . By controlling the supply gas pressure to be in a range of 13 to 1,330 Pa and a sheath width to be made in a range of 2 to 30 mm, the discharge is kept stably. As a consequence, it can be realized to form amorphous carbon films efficiently at a low cost.
1. An amorphous carbon film forming method of forming amorphous carbon films on surfaces of conductive plate-like workpieces by a plasma CVD method, comprising the steps of:
arranging plural plate-like workpieces on a workpiece fixture, which provided in a film forming furnace to be connected to a negative electrode, in a state that the plate-like workpieces are stacked in parallel and adjoining workpieces have facing surfaces spaced from one another by an interval in the stacking direction of the plate-like workpieces;
providing plasma power to the film forming furnace to produce a plasma in the film forming furnace and a sheath formed around each of said plate-like workpieces, wherein the sheath of each of said plate-like workpieces has a sheath width comprising the width of the sheath in the stacking direction; and
controlling a processing gas pressure and a plasma power supply so that the sheath width becomes equal to or less than the interval between the facing surfaces of two adjoining plate-like workpieces.
2. The amorphous carbon film forming method as set forth in claim 1 , wherein the processing gas pressure is in a range of 13 to 1,330 Pa, and wherein the interval between the facing surfaces of the two adjoining plate-like workpieces is in a range of 2 to 30 mm.
3. The amorphous carbon film forming method as set forth in claim 2 , wherein the processing gas pressure is in a range of 66.5 to 1,064 Pa.
4. The amorphous carbon film forming method as set forth in claim 3 , wherein the processing gas pressure is in a range of 266 to 798 Pa.
5. The amorphous carbon film forming method as set forth in claim 2 , wherein the interval between the facing surfaces of the two adjoining plate-like workpieces is in a range of 3 to 20 mm.
6. The amorphous carbon film forming method as set forth in claim 5 , wherein the interval between the facing surfaces of the two adjoining plate-like workpieces is in a range of 5 to 15 mm.
7. The amorphous carbon film forming method as set forth in claim 1 , wherein the plate-like workpieces have a disc shape.
8. The amorphous carbon film forming method as set forth in claim 1 , wherein the plate-like workpieces are clutch plates.
9. The amorphous carbon film forming method as set forth in claim 1 , wherein the processing gas is a mixed gas consisting of one or more kinds selected from organometallic bearing gases and halogen compound including at least Si and also consisting of one or more kinds selected from hydrocarbon gases.
10. The amorphous carbon film forming method as set forth in claim 9 , wherein the organometallic bearing gases are tetramethylsilane and silane.
11. The amorphous carbon film forming method as set forth in claim 9 , wherein the halogen compound is silicon tetrachloride.
12. The amorphous carbon film forming method as set forth in claim 9 , wherein the hydrocarbon gases are methane, ethylene, acetylene and benzene.
13. The amorphous carbon film forming method as set forth in claim 1 , wherein the film forming furnace has a cylindrical furnace chamber, in which the workpiece fixtures are arranged at a regular angular interval on a circle having a center coaxial with the furnace chamber, in which plural tubular nozzles for supplying the processing gas are arranged at a regular angular interval on another circle which surrounds the workpiece fixtures with a center thereof coaxial with the furnace chamber, and in which at least one tubular nozzle is further arranged at the center of the furnace chamber to extend vertically in parallel to the plural tubular nozzles.