Diamond film deposition with a microwave plasma

Claim 2

A process for depositing diamond film on the surface of a substrate comprising the steps of: providing a microwave plasma generating apparatus including a microwave cavity tuneable by means of adjusting the height thereof and the depth of insertion of an antenna, an electrically chamber comprising insulating material within said cavity, including a gas supply for injecting gases into said chamber and a platform for supporting a substrate within said chamber; decreasing the pressure within said chamber; creating a plasma including hydrogen gas within said chamber; tuning said cavity to position the plasma such that it encompasses the surface of said substrate on which diamond is to be deposited; heating said substrate to a temperature range in which deposition of diamond can occur; injecting a hydrocarbon gas into said plasma; and maintaining said plasma for sufficient time for depositing diamond film of a desired thickness.

Claim 3

The process of claim 1 wherein said cavity has a continuously adjustable height and said tuning step comprises adjusting the height of said cavity.

Claim 4

The process of claims 1 or 2 wherein the depth of insertion of said antenna is continuously adjustable and said tuning step further comprises continuously adjusting the depth of insertion of said antenna.

Claim 5

The process of claim 1, wherein said plasma has a height less than its diameter.

Claim 6

The process of claim 1 further comprising maintaining said pressure in said cavity at at least 30 torr after creating said plasma.

Claim 7

The process of claims 1 or 5 wherein said substrate is heated to between about 950° C.-1,100° C.

Claim 8

The process of claims 1 or 5 further comprising polishing said substrate before depositing said diamond film.

Claim 9

The process of claims 1 or 5 wherein the concentration of said hydrocarbon gas is between about 0.2-2.5% of the concentration of said hydrogen gas.

Claim 10

The process of claims 1 or 5 wherein said substrate is chosen from the group consisting of silicon, silicon nitride, silicon carbide, sialon, aluminum oxide or germanium.

Claim 11

The process of claims 1 or 5 wherein said substrate comprises tungsten carbide coated with tungsten or titanium nitride.

Claim 12

The process of claims 1 or 5 wherein said substrate is supported by a graphite susceptor, pyrophyllite, boron nitride and a steel plate.

Claim 13

The process of claim 1 wherein said heating step comprises first heating said substrate to between about 800° C.-900° C. for between about 1-2 hours, and then increasing said temperature of said substrate to between about 950° C.-1,100° C.

Claim 14

A process for depositing diamond film on the surface of a substrate in a tuneable microwave cavity having an adjustable height and an antenna having an adjustable depth of insertion, and including an electrically plasma chamber comprising insulating material, said process comprising the steps of; decreasing the pressure in said plasma chamber; injecting an inert gas into said plasma chamber; igniting said inert gas by microwave power; injecting hydrogen gas into said plasma chamber; ceasing the injection of said inert gas after said hydrogen gas ignites; maintaining the pressure in said chamber at a selected level; positioning said plasma and tuning said cavity by adjusting the height of said cavity and the depth of insertion of said antenna for minimizing reflected power and forming said plasma such that it encompasses said surface of said substrate; heating said substrate to a temperature at which diamond deposition can occur; injecting hydrocarbon gas into said plasma; maintaining said plasma for a sufficient time to deposit the desired thickness of diamond film.

Claim 15

A process for depositing diamond film on the surface of a substrate in a tuneable microwave cavity having an adjustable height and an antenna having an adjustable depth of insertion, and including an electrically plasma chamber comprising insulating material, said process comprising the steps of; decreasing the pressure in said plasma chamber; injecting an inert gas into said plasma chamber; igniting said inert gas by microwave power; injecting hydrogen gas into said plasma chamber; ceasing the injection of said inert gas after said hydrogen gas ignites; maintaining the pressure in said chamber at a selected level; positioning said plasma and tuning said cavity by adjusting the height of said cavity and the depth of insertion of said antenna for minimizing reflected power and forming said plasma such that it encompasses said surface of said substrate; heating said substrate to a temperature at which diamond deposition can occur; injecting hydrocarbon gas into said plasma; maintaining said plasma for a sufficient time to deposit the desired thickness of diamond film.

Claim 16

The process of claim 13 further comprising adjusting the height of said substrate.

Claim 17

The process of claim 13, further comprising roughening the surface of said substrate before coating.

Claim 18

The process of claim 15 wherein said polishing step comprises placing said substrate on a silk cloth, and rotating said silk cloth by a wheel with diamond paste between about 0.10-1 micron.

Claim 19

The process of claim 13 wherein the microwave power emitted by said antenna is between about 600-900 watts.

Claim 20

The process of claim 13, wherein said hydrocarbon is methane or acetylene, at a concentration between about 0.2-2.5% of the hydrogen concentration.

Claim 21

The process of claim 13 wherein said substrate is chosen from the group consisting of silicon, silicon nitride, silicon carbide, or sialon, alumina or germanium.

Claim 22

The process of claim 13 wherein said hydrocarbon gas is methane, at a concentration between 0.5-2.0% the concentration of the hydrogen gas.

Claim 23

The method of claim 13 further comprising heating said substrate to between about 800° C.-900° C. after positioning said plasma, injecting said hydrocarbon into said chamber, and maintaining said substrate at between about 600° C.-900° C. for about 1-2 hours, and then increasing said temperature of said substrate to between about 900° C.-1,100° C.

Claim 24

The process of claim 13 wherein said plasma overlaps at least 20% of the side of said substrate.

Claim 25

A process for coating identical substrates with diamond film in a tuneable microwave cavity having an adjustable height and an antenna having an adjustable depth of insertion, and including a plasma chamber comprising electrically insulating material, comprising the steps of placing a first substrate in said chamber of said apparatus; decreasing the pressure within said chamber; creating a plasma including hydrogen gas within said chamber; maintaining the pressure in said chamber at at least 30 torr; selecting the tuning of said cavity and the position of said substrate to position the plasma such that said surface of said substrate lies within said plasma; heating said substrate to a temperature sufficient for depositing the desired diamond film; injecting a hydrocarbon gas into said plasma; continuing said deposition for a sufficient time to deposit the desired thickness of diamond film on said substrate; replacing said substrate with an uncoated substrate of the same type; repeating said decreasing step, said creating step, said maintaining step, said heating step, said injecting step, said continuing step and said replacing step, until the desired number of substrates have been coated.

Claim 26

A process for coating identical substrates with diamond film in a tuneable microwave cavity having an adjustable height and an antenna having an adjustable depth of insertion, and including a plasma chamber comprising electrically insulating material, comprising the steps of placing a first substrate in said chamber of said apparatus; decreasing the pressure within said chamber; creating a plasma including hydrogen gas within said chamber; maintaining the pressure in said chamber at at least 30 torr; selecting the tuning of said cavity and the position of said substrate to position the plasma such that said surface of said substrate lies within said plasma; heating said substrate to a temperature sufficient for depositing the desired diamond film; injecting a hydrocarbon gas into said plasma; continuing said deposition for a sufficient time to deposit the desired thickness of diamond film on said substrate; replacing said substrate with an uncoated substrate of the same type; repeating said decreasing step, said creating step, said maintaining step, said heating step, said injecting step, said continuing step and said replacing step, until the desired number of substrates have been coated.

Claim 27

The process of claim 23 wherein said hydrocarbon gas comprises methane, at a concentration between 0.2-2.5% of the hydrogen concentration.

Claim 28

The process of claim 23 further comprising heating said substrate to between about 800° C.-1,200° C.

Claim 29

The process of claims 23 further comprising heating said substrate to between about 950° C.-1,100° C.

Claim 30

The process of claim 26 further comprising varying the tuning of said plasma to properly position said plasma by varying the height of the cavity and the depth of insertion of said antenna.

Claim 31

A process for depositing diamond film on the surface of a substrate in a tuneable microwave cavity having a continuously adjustable height and an antenna having a continuously adjustable depth of insertion, and including an plasma chamber comprising electrically insulating material, comprising the steps of: setting said height and said depth of insertion of said tuneable microwave cavity, said setting based on said substrate and said deposition conditions; decreasing the pressure within said chamber; creating a plasma including hydrogen gas within said chamber at a pressure of at least about 30 torr; heating said substrate to between 800° C.-1,200° C.; injecting a hydrocarbon gas into said plasma; and monitoring said plasma to ensure it is in its proper position.

Claim 32

A process for depositing diamond film on the surface of a substrate in a tuneable microwave cavity having a continuously adjustable height and an antenna having a continuously adjustable depth of insertion, and including an plasma chamber comprising electrically insulating material, comprising the steps of: setting said height and said depth of insertion of said tuneable microwave cavity, said setting based on said substrate and said deposition conditions; decreasing the pressure within said chamber; creating a plasma including hydrogen gas within said chamber at a pressure of at least about 30 torr; heating said substrate to between 800° C.-1,200° C.; injecting a hydrocarbon gas into said plasma; and monitoring said plasma to ensure it is in its proper position.

Claim 33

The process of claim 28 wherein said heating step comprises heating said substrate to between about 950° C.-1,100° C.

Claim 34

The process of claim 28 wherein said hydrocarbon gas is set on a concentration between about 0.2-2.5% of the concentration of said hydrogen.

Claim 35

The process of claim 1, wherein said substrate is a tool.

Claim 36

The process of claim 1, wherein said surface of said substrate is uneven, said uneven surface lying within said plasma.

Claim 37

The process of claim 1, wherein said chamber comprising electrically insulating material comprises a quartz bell jar resting on a base plate, said base plate including cooling means for carrying fluid for cooling said base plate.

Claim 38

The process of claims 1, wherein said method further comprises pumping nitrogen gas into said cavity for cooling said bell jar.

Claim 39

The process of claim 1, wherein said substrate is placed on a graphite susceptor for supporting and heating said substrate.