Apparatus for plasma assisted evaporation of thin films and corresponding method of deposition

Claim 2

An improved method of depositing a thin film onto a substrate, said method including the steps of: vacuumizing a chamber; providing an electrically unbiased substrate in the chamber; providing a supply of solid vaporizable material in the chamber; heating the solid material with electron beam means so as to vaporize said material in a vapor zone formed between the substrate and the supply of solid material; disposing electrode means in the vapor zone, said electrode means operatively disposed in electrical communication with a source of alternating current; providing an ionizable gas; and, activating the source of alternating current so as to energize the electrode means and develop an ionized plasma from at least the ionized gas, said ionized plasma developed in a plasma region formed proximate the electrode means; whereby the vaporized solid material is activated by the plasma and deposited as a thin film onto the substrate.

Claim 3

A method as in claim 1, including the further steps of: introducing a reactive gas proximate the plasma region; and activating the reactive gas in the plasma region, whereby the activated gas and the reactive vapor of the solid material react for the deposition thereof as a thin film.

Claim 4

A method as in claim 1, including the further step of: maintaining the substrate at a temperature of about room temperature to 300° C. during the deposition of the thin film thereonto.

Claim 5

A method as in claim 1, including the further step of: selecting the solid material from the group consisting essentially of: In, Sn, Cd, Zn, Ti, Si, Ge and mixtures thereof.

Claim 6

A method as in claim 2, including the further step of: selecting the reactive gas from the group consisting essentially of: O 2 , N 2 , NH 3 , CH 4 , H 2 S N 2 O, CF 4 and mixtures thereof.

Claim 7

A method as in claim 1, wherein the step of energizing the electrode means with alternating current comprises: energizing the electrode means with radio frequency energy.

Claim 8

A method as in claim 1, wherein the step of energizing the electrode means with alternating current comprises: energizing the electrode means with microwave energy.

Claim 9

A method as in claim 1, including the further step of: maintaining the pressure within the chamber in the range of 10 -2 -10 -4 torr.

Claim 10

A method as in claim 1, including the further step of: continuously advancing the substrate through the chamber, whereby a thin film is continuously deposited upon the advancing substrate.

Claim 11

A method as in claim 2, wherein: the step of heating the solid vaporizable material with electron beam means comprises the heating of an indium:tin alloy; the step of introducing a reactive gas comprises the introduction of oxygen; and the method includes the further step of maintaining the substrate at a temperature from about room temperature to 300° C.

Claim 12

A method as in claim 2, wherein: the step of heating the solid vaporizable material comprises heating indium with electron beam means; the step of introducing a reactive gas comprises the introduction of oxygen; and the method includes the further step of maintaining the substrate at a temperature of up to 300° C.

Claim 13

A method as in claim 1, wherein the substrate in the chamber includes a body of semiconductor material thereupon.

Claim 14

A method as in claim 1, wherein the substrate in the chamber includes having a plurality of amorphous semiconductor layers thereupon.

Claim 15

Apparatus for depositing a thin film onto a substrate, said apparatus including: a vacuum chamber; means for vacuumizing the chamber; means for supporting an electrically unbiased substrate; a source of solid vaporizable material operatively disposed in the vacuum chamber; electron beam means adapted to vaporize the solid material in a vapor zone formed between the substrate and the supply of solid material; a source of ionizable gas; electrode means operatively disposed proximate the source of solid material in the vapor zone; said electrode means adapted to develop an ionized plasma from at least the ionizable gas, said plasma developed in a plasma region formed proximate the electrode means; and a source of alternating current operatively disposed in electrical communication with the electrode means, whereby activating the source develops the plasma and the plasma activates the vaporized solid material for the deposition thereof as a thin film onto the substrate.

Claim 16

Apparatus for depositing a thin film onto a substrate, said apparatus including: a vacuum chamber; means for vacuumizing the chamber; means for supporting an electrically unbiased substrate; a source of solid vaporizable material operatively disposed in the vacuum chamber; electron beam means adapted to vaporize the solid material in a vapor zone formed between the substrate and the supply of solid material; a source of ionizable gas; electrode means operatively disposed proximate the source of solid material in the vapor zone; said electrode means adapted to develop an ionized plasma from at least the ionizable gas, said plasma developed in a plasma region formed proximate the electrode means; and a source of alternating current operatively disposed in electrical communication with the electrode means, whereby activating the source develops the plasma and the plasma activates the vaporized solid material for the deposition thereof as a thin film onto the substrate.

Claim 17

Apparatus as in claim 14, further including: gas inlet means adapted to introduce a reactive gas proximate the plasma region, whereby the reactive gas and activated vapor of the solid material react to deposit the thin film onto the substrate.

Claim 18

Apparatus as in claim 14, further including: means for heating the substrate to a temperature from about room temperature to 300° C. during the deposition of the thin film thereonto.

Claim 19

Apparatus as in claim 14, further including: means adapted to continuously move the substrate through the chamber at a preselected rate of speed, whereby a thin film of preselected thickness may be continuously deposited onto the substrate.

Claim 20

Apparatus as in claim 14, further including: thickness monitoring means for measuring the thickness of the thin film as it is deposited.

Claim 21

Apparatus as in claim 14, further including: a first crucible in which the source of solid material is disposed; and control means adapted to (1) control the energy and intensity of the electron beam means, and (2) direct the electron beam means to impinge upon the solid material in the crucible for the vaporization thereof.

Claim 22

Apparatus as in claim 19, further including: at least two crucibles in each of which the source of solid material is disposed; and said control means is further adapted to direct the electron beam means to sequentially impinge upon the material in each of the crucibles.

Claim 23

Apparatus as in claim 14, wherein the electrode means comprises: a first generally planar metallic plate having an aperture formed therein; a second generally planar metallic plate disposed in spaced relation to a first surface of said first plate and having an aperture formed therein; and a third generally planar metallic plate disposed in spaced relation to the second surface of the first generally planar plate, said third plate having an aperture formed therein, the apertures in the first, second and third plates being generally aligned.

Claim 24

Apparatus as in claim 21, wherein the first plate is in electrical communication with the source of alternating current, and the second and third plates are electrically grounded.

Claim 25

Apparatus as in claim 21, wherein the apertures in the first, second and third plates are generally circular and the aperture in the first plate has a diameter less than the diameter of the apertures in the second and third plates.

Claim 26

Apparatus as in claim 21, wherein the first metallic plate further includes a relatively thin, electrically conductive member in electrical communication therewith and extending at least partially across the aperture thereof.

Claim 27

Apparatus as in claim 21, wherein the first metallic plate further includes an electrically conductive metallic mesh extending at least partially across the aperture thereof and in electrical communication therewith.

Claim 28

Apparatus as in claim 14, wherein the source of alternating current is adapted to provide radio frequency energy.

Claim 29

Apparatus as in claim 14, wherein the source of alternating current is adapted to provide microwave energy.

Claim 30

Apparatus as in claim 14, wherein the source of solid material is adapted to provide a material selected from the group consisting essentially of: In, Sn, Cd, Zn, Ti, Si, Ge and mixtures thereof.

Claim 31

Apparatus as in claim 15, wherein the gas inlet means is adapted to provide a reactive gas selected from the group consisting essentially of: O 2 , N 2 , NH 3 , CH 4 , H 2 S, N 2 O, CF 4 and mixtures thereof.