# US 5,702,530 A · Distributed microwave plasma reactor for semiconductor processing

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- Number: US 5,702,530 A
- Document ID: US5702530A
- Status: Granted
- Kind: A
- Application number: 08/494,297
- Filed: 1995-06-23
- Granted: 1997-12-30
- Earliest claimed: 1995-06-23
- Assignees: Applied Materials, Inc.
- Inventors: Hongching Shan; Harald Herchen; Michael Welch
- Web page: https://patentgrep.com/patent/US5702530A

## CPC

- C23C 16/45565: {Shower nozzles}
- C23C 16/452: by activating reactive gas streams before {their} introduction into the reaction chamber, e.g. by {ionisation} or addition of reactive species
- C23C 16/511: using microwave discharges
- C23C 16/52: Controlling or regulating the coating process {(C23C16/45557, C23C16/279 take precedence)}
- H01J 37/32229: {Waveguides}
- H01J 37/32357: {Generation remote from the workpiece, e.g. down-stream}
- H01J 37/3244: {Gas supply means}
- Y10S 438/935: Gas flow control
- C23C: COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL (making metal-coated products by extrusion B21C23/22; covering with metal by connecting pre-existing layers to articles, see the relevant places, e.g. B21D39/00, B23K; metallising of glass C03C; metallising mortars, concrete, artificial stone, ceramics or natural stone C04B41/00; enamelling of, or applying a vitreous layer to, metals C23D; treating metal surfaces or coating of metals by electrolysis or electrophoresis C25D; single-crystal film growth C30B; by metallising textiles D06M11/83; decorating textiles by locally metallising D06Q1/04)
- H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H)
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

## Abstract

A plasma reactor has plural dielectric gas injection tubes extending from a gas injection source and through a microwave guide and into the top of the reactor chamber. The semiconductor wafer rests near the bottom of the chamber on a wafer pedestal connected to a bias RF power source which is controlled independently of the microwave source coupled to the microwave guide. The microwaves from the waveguide ignite and maintain a plasma in each of the tubes. Gas flow through the tubes carries the plasmas in all the tubes into the chamber and into contact with the wafer surface.

## Claims

### Claim 1

A plasma reactor, comprising:
a vacuum chamber and a wafer supporter for holding a semiconductor wafer in said chamber;
a reactant gas source for furnishing at least a reactant gas;
a radiation applicator outside said chamber; and
plural gas flow channels outside of said chamber, each having a hollow interior and plural respective individually adjustable valves, said channels extending from said reactant gas source and through a ceiling of said chamber, a portion of each one of said channels extending through said radiation applicator for irradiation of an interior of each of said channels whereby to generate a plasma therein which can be transported through said channels toward said chamber, said reactant gas source establishing gas flow rates in respective ones of said gas flow channels in accordance with adjustments of respective ones of said valves whereby said reactant gas flows through each of said channels toward said chamber.

### Claim 2 (depends on 1)

The reactor of claim 1 wherein said wafer supporter comprises a wafer pedestal near a floor of said chamber and wherein said channels extend through said ceiling of said chamber and toward a top surface of said wafer.

### Claim 3 (depends on 2)

The reactor of claim 2 further comprising a bias RF power source coupled to said wafer pedestal for controlling ion energy near said wafer.

### Claim 4 (depends on 1)

The reactor of claim 1 wherein each of said channels comprises a channel formed of a dielectric material of the type including quartz or sapphire.

### Claim 5 (depends on 1)

The reactor of claim 1 wherein said gas source comprises:
a valve apparatus for individually supplying gas to respective ones of said channels at respective individual gas flow rates.

### Claim 6 (depends on 5)

The reactor of claim 5 wherein said valve apparatus for individually supplying gas to respective ones of said channels comprises plural mass flow controllers, each one of said mass flow controllers having a gas input connected to a common supply, a gas output connected to a respective one of said channels and an electrical control input for setting a gas flow rate between said input and output in accordance with an electrical signal applied to said control line.

### Claim 7 (depends on 6)

The apparatus of claim 6 further comprising an array controller connected to each said control line for simultaneously controlling individual gas flow rates through each of said channels.

### Claim 8 (depends on 6)

The apparatus of claim 6 further comprising a means for establishing a gas pressure within said chamber.

### Claim 9 (depends on 1)

The reactor of claim 1 wherein said plural gas flow channels comprise at least five individual channels.

### Claim 10 (depends on 1)

The reactor of claim 1 wherein said plural gas flow channels comprise at least nine individual channels.

### Claim 11 (depends on 1)

The reactor of claim 1 wherein said plural gas flow channels comprise channels each with a diameter of less than one-fifth of diameter of said chamber.

### Claim 12 (depends on 1)

The reactor of claim 1 wherein said radiation applicator comprises a waveguide through which said portion of respective ones of said channels extend.

### Claim 13 (depends on 12)

The reactor of claim 12 wherein said waveguide comprises a fan-shaped main portion through which said channels extend and a neck coupled to an apex of said fan-shaped main portion, and wherein said means for irradiating further comprises a source of electromagnetic radiation coupled to said neck.

### Claim 14 (depends on 13)

The reactor of claim 13 wherein said source of electromagnetic radiation comprises a microwave generator, and wherein said waveguide comprises a microwave guide.

### Claim 15 (depends on 1)

The reactor of claim 1 wherein said radiation applicator comprises an inductive applicator.

### Claim 16 (depends on 15)

The reactor of claim 15 wherein said inductive applicator comprises an inductor coil surrounding said plural gas flow channels.

### Claim 17 (depends on 1)

The reactor of claim 1 wherein said radiation applicator comprises inductor coils surrounding respective ones of said plural gas flow channels.

### Claim 18 (depends on 1)

The reactor of claim 1 wherein said radiation applicator comprises a capacitive applicator.

### Claim 19 (depends on 18)

The reactor of claim 18 wherein said capacitive applicator comprises a pair of capacitor plates sandwiching said plural gas flow channels.

### Claim 20 (depends on 1)

The reactor of claim 1 wherein said radiation applicator comprises capacitor plates radially sandwiching respective ones of said plural gas flow channels.

### Claim 21

A plasma reactor, comprising:
a vacuum chamber and a wafer supporter for holding a semiconductor wafer in said chamber;
a reactant gas source for furnishing at least a reactant gas;
plural gas flow channels extending from said reactant gas source and through a ceiling of said chamber, said reactant gas source establishing gas flow rates in respective ones of said plural gas flow channels whereby said reactant gas flows through each of said channels toward said chamber, each of said plural gas flow channels having an intermediate portion lying between said reactant gas source and said chamber;
a radiation applicator for irradiating an interior of said intermediate portion of respective ones of said channels whereby to provide a plasma therein, the gas flow rates in said channels being sufficient to transport the plasma in each channel into said chamber;
said radiation applicator comprises a waveguide;
said waveguide comprises a fan-shaped main portion through which said channels extend and a neck coupled to an apex of said fan-shaped main portion, and wherein said radiation applicator further comprises a source of electromagnetic radiation coupled to said neck; and
said source of electromagnetic radiation comprises a microwave generator, and wherein said waveguide comprises a microwave guide.

### Claim 22 (depends on 21)

The reactor of claim 21 wherein said plural gas flow channels comprise at least five individual channels.

### Claim 23 (depends on 21)

The reactor of claim 21 wherein said plural gas flow channels comprise at least nine individual channels.

### Claim 24 (depends on 21)

The reactor of claim 21 wherein said plural gas flow channels comprise channels each with a diameter of less than one-fifth of diameter of said chamber.

### Claim 25

In a plasma reactor for processing a semiconductor wafer inside a vacuum chamber, a method for providing uniform gas flow rates across a wafer surface, said method comprising:
providing an array of gas distribution channels outside of said chamber, each of said channels having a hollow interior and plural respective individually adjustable valves, said channels extending through a ceiling of said chamber such that said channels are facing said wafer;
providing a gas flow supply;
supplying gas to respective ones of said gas distribution channels from said gas flow supply at respective individual gas flow rates; and
irradiating portions of each of said channels outside of said chamber with sufficient radiation to ionize gases within said channels, whereby to furnish plasma from said channels to said chamber.

### Claim 26 (depends on 25)

The method of claim 25 further comprising simultaneously controlling individual gas flow rates through each of said channels to achieve an optimization of gas flow uniformity across the surface of said wafer.

### Claim 27 (depends on 26)

The method of claim 26 further comprising establishing a gas pressure within said chamber.

### Claim 28

A plasma reactor, comprising:
a vacuum chamber and a wafer supporter for holding a semiconductor wafer in said chamber;
a reactant gas source for furnishing at least a reactant gas;
a radiation apparatus outside said chamber; and
plural gas flow channels outside of said chamber, each having a hollow interior and plural respective individually adjustable valves, said channels extending from said reactant gas source and through a ceiling of said chamber, a portion of each one of said channels extending through said radiation apparatus for irradiation of an interior of each of said channels whereby to generate plasma therein which can be transported through said channels toward said chamber.

### Claim 29 (depends on 28)

The reactor of claim 28 wherein said wafer supporter comprises a wafer pedestal near a floor of said chamber and wherein said channels extend through said ceiling of said chamber and toward a top surface of said wafer.

### Claim 30 (depends on 28)

The reactor of claim 28 wherein each of said channels comprises a channel formed of a dielectric material of the type including quartz or sapphire.

### Claim 31 (depends on 28)

The reactor of claim 28 wherein said gas source comprises:
an apparatus for individually supplying gas to respective ones of said plural gas flow channels at respective individual gas flow rates.

### Claim 32 (depends on 28)

The reactor of claim 28 wherein said plural gas flow channels comprise at least five individual channels.

### Claim 33 (depends on 28)

The reactor of claim 28 wherein said plural gas flow channels comprise at least nine individual channels.

### Claim 34 (depends on 28)

The reactor of claim 28 wherein said plural gas flow channels comprise channels each with a diameter of less than one-fifth of diameter of said chamber.

### Claim 35 (depends on 28)

The reactor of claim 28 wherein said radiation apparatus comprises a waveguide through which said portion of respective ones of said channels extend.

### Claim 36 (depends on 35)

The reactor of claim 35 wherein said waveguide comprises a fan-shaped main portion through which said channels extend and a neck coupled to an apex of said fan-shaped main portion, and wherein said means for irradiating further comprises a source of electromagnetic radiation coupled to said neck.

### Claim 37 (depends on 36)

The reactor of claim 36 wherein said source of electromagnetic radiation comprises a microwave generator, and wherein said waveguide comprises a microwave guide.

### Claim 38 (depends on 28)

The reactor of claim 28 wherein said radiation apparatus comprises an inductive applicator.

### Claim 39 (depends on 38)

The reactor of claim 38 wherein said inductive applicator comprises an inductor coil surrounding said plural gas flow channels.

### Claim 40 (depends on 28)

The reactor of claim 28 wherein said radiation apparatus comprises inductor coils surrounding respective ones of said plural gas flow channels.

### Claim 41 (depends on 28)

The reactor of claim 28 wherein said radiation apparatus comprises a capacitive applicator.

### Claim 42 (depends on 41)

The reactor of claim 41 wherein said capacitive applicator comprises a pair of capacitor plates sandwiching said plural gas flow channels.

### Claim 43 (depends on 28)

The reactor of claim 28 wherein said radiation apparatus comprises capacitor plates radially sandwiching respective ones of said plural gas flow channels.

### Claim 44

A plasma reactor, comprising:
a vacuum chamber and a wafer supporter for holding a semiconductor wafer in said chamber;
a reactant gas source for furnishing at least a reactant gas;
plural gas flow channels extending from said reactant gas source and through a ceiling of said chamber, each of said plural gas flow channels having an intermediate portion lying between said reactant gas source and said chamber;
a radiation apparatus for irradiating an interior of said intermediate portion of each of said channels whereby to provide a plasma therein, the gas flow rates in said channels being sufficient to transport the plasma in each of said channels into said chamber;
said radiation apparatus comprises a waveguide;
said waveguide comprises a fan-shaped main portion through which said channels extend and a neck coupled to an apex of said fan-shaped main portion, and wherein said radiation apparatus further comprises a source of electromagnetic radiation coupled to said neck; and
said source of electromagnetic radiation comprises a microwave generator, and wherein said waveguide comprises a microwave guide.

### Claim 45 (depends on 44)

The reactor of claim 44 wherein said plural gas flow channels comprise at least five individual channels.

### Claim 46 (depends on 44)

The reactor of claim 44 wherein said plural gas flow channels comprise at least nine individual channels.

### Claim 47 (depends on 44)

The reactor of claim 44 wherein said plural gas flow channels comprise channels each with a diameter of less than one-fifth of diameter of said chamber.

### Claim 48

A plasma reactor, including a reactor chamber for processing a substrate therewithin in a subatmospheric gaseous environment, said plasma reactor being adapted to accept an external supply of gas, and an external supply of electromagnetic radiation, said plasma reactor comprising:
a workpiece support;
a plurality of gas flow channels outside of said chamber, each having a hollow interior and plural respective individually adjustable valves, said channels extending through the ceiling of said reactor chamber and terminating in respective orifices directing gas towards said workpiece support within said chamber, each of said plural gas flow channels adapted to communicate with a supply of gas outside of said plasma reactor;
and an electromagnetic radiation applicator outside said chamber through which each of said plural gas flow channels extend and transmitting electromagnetic radiation from an external source of electromagnetic radiation to locations within each of said plural gas flow channels;
whereby gas flowing through each of said plural gas flow channels is ignited into a plasma, said plasma being transported into said chamber and directed toward said workpiece support.

### Claim 49 (depends on 48)

A plasma reactor as in claim 48, wherein said workpiece support is adapted to accept RF power from an external source of RF power, so that said workpiece support may be biased for control of plasma ion energy.

### Claim 50 (depends on 48)

A plasma reactor as in claim 48 wherein each of said channels comprises a channel formed of a dielectric material.

### Claim 51 (depends on 48)

A plasma reactor as in claim 48, wherein said plural valves comprises mass flow controllers at inputs of said channels, whereby a gas flow can be controlled and plasma characteristics can be varied over an area of said workpiece support.

### Claim 52 (depends on 48)

A plasma reactor as in claim 48, which further includes a plurality of gas flow controllers, one for each respective particular desired source gas, and having a common output supplying the inputs of said channels, such that the gas composition of the plasma may be controlled.

### Claim 53 (depends on 48)

A plasma reactor as in claim 48 wherein said plural gas flow channels comprise at least five individual channels.

### Claim 54 (depends on 48)

A plasma reactor as in claim 48 wherein said plural gas flow channels comprise at least nine individual channels.

### Claim 55 (depends on 48)

A plasma reactor as in claim 48 wherein said plural gas flow channels comprise channels each with a diameter of less than one-fifth of diameter of said chamber.

### Claim 56 (depends on 48)

A plasma reactor as in claim 48 wherein said electromagnetic radiation applicator comprises a waveguide through which said plural gas flow channels extend.

### Claim 57 (depends on 56)

A plasma reactor as in claim 56 wherein said waveguide comprises a fan-shaped main portion through which said channels extend and a neck coupled to an apex of said fan-shaped main portion, and wherein said electromagnetic radiation applicator further comprises a source of electromagnetic radiation coupled to said neck.

### Claim 58 (depends on 57)

A plasma reactor as in claim 57 wherein said source of electromagnetic radiation comprises a microwave generator, and wherein said waveguide comprises a microwave guide.

### Claim 59 (depends on 48)

A plasma reactor as in claim 48 wherein said electromagnetic radiation applicator comprises an inductive applicator.

### Claim 60 (depends on 59)

A plasma reactor as in claim 59 wherein said inductive applicator comprises an inductor coil surrounding said plural gas flow channels.

### Claim 61 (depends on 48)

A plasma reactor as in claim 48 wherein said electromagnetic radiation applicator comprises inductor coils surrounding respective ones of said plural gas flow channels.

### Claim 62 (depends on 48)

A plasma reactor as in claim 48 wherein said electromagnetic radiation applicator comprises a capacitive applicator.

### Claim 63 (depends on 62)

A plasma reactor as in claim 62 wherein said capacitive applicator comprises a pair of capacitor plates sandwiching said plural gas flow channels.

### Claim 64 (depends on 48)

A plasma reactor as in claim 48 wherein said electromagnetic radiation applicator comprises capacitor plates radially sandwiching respective ones of said plural gas flow channels.