# US 9,520,294 B2 · Atomic layer etch process using an electron beam

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 9,520,294 B2
- Document ID: US9520294B2
- Status: Granted
- Kind: B2
- Application number: 14/505,148
- Filed: 2014-10-02
- Published: 2016-03-03
- Granted: 2016-12-13
- Earliest claimed: 2014-08-29
- Assignees: Applied Materials, Inc.
- Applicants: Applied Materials, Inc.
- Inventors: Ankur Agarwal; Rajinder Dhindsa; Shahid Rauf
- Web page: https://patentgrep.com/patent/US9520294B2

## CPC

- H10P 50/244: {comprising alternated and repeated etching and passivation steps}
- B81C 1/00531: {Dry etching}
- H01J 37/32357: {Generation remote from the workpiece, e.g. down-stream}
- H01J 37/32706: {Polarising the substrate}
- H10P 50/242: {of Group IV materials}
- H10P 50/246: {of Group III-V materials}
- H10P 50/266: {by vapour etching only}
- H10P 50/283: {by chemical means}
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- B81C: PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS (making microcapsules or microballoons B01J13/02; processes or apparatus specially adapted for the manufacture or treatment of piezoelectric, electrostrictive or magnetostrictive elements per se H10N30/01)
- H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H)

## Abstract

Atomic layer etching using alternating passivation and etching processes is performed with an electron beam plasma source, in which the ion energy is set to a low level below the etch threshold of the material to be etched during passivation and to a higher level above the etch threshold during etching but below the etch threshold of the unpassivated material.

## Claims

### Claim 1

A method of removing an overlying film from a workpiece, comprising:
supporting the workpiece in a chamber;
coupling an RF bias voltage to said workpiece;
(A) performing a passivation process for a time duration corresponding to a desired thickness of a layer of said overlying film to be passivated, said passivation process comprising:
introducing a passivation process gas into said chamber;
generating a plasma in said chamber for passivation, by radiating gas in said chamber with an electron beam having a beam direction parallel to a plane of said workpiece from an electron beam generator;
controlling said RF bias voltage to set energy of ions in said chamber to a first ion energy level less than a first minimum ion energy required for etching said overlying film;
(B) performing an etching process by:
introducing an etching process gas into said chamber;
generating a plasma in said chamber for etching, by radiating gas in said chamber with an electron beam having a beam direction parallel to a plane of said workpiece from an electron beam generator;
controlling said RF bias voltage to set energy of ions in said chamber to a second ion energy level exceeding said first minimum ion energy;
wherein said controlling said RF bias voltage to set energy of ions to a first ion energy level comprises conforming a time domain waveform of said RF bias voltage to an RF waveform in which the RF voltage is at a level corresponding to said first ion energy level for a duration of about 50% of a continuous wave RF cycle of said RF waveform; and
wherein said controlling said RF bias voltage to set energy of ions to a second ion energy level comprises conforming a time domain waveform of said RF bias voltage to an RF waveform in which the RF voltage is at a level corresponding to said second ion energy level for a duration of about 50% of a continuous wave RF cycle of said RF waveform.

### Claim 2 (depends on 1)

The method of claim 1 wherein said workpiece comprises a base material under said overlying film, and said second ion energy level is less than a second minimum ion energy required to etch said base material.

### Claim 3 (depends on 1)

The method of claim 1 wherein said desired thickness is one atomic layer.

### Claim 4 (depends on 1)

The method of claim 1 wherein said passivating is performed for a time duration sufficiently short to limit thickness of said layer to one atomic layer.

### Claim 5 (depends on 1)

The method of claim 1 wherein said passivating gas contains a halogen species.

### Claim 6 (depends on 1)

The method of claim 1 wherein said passivating gas contains Chlorine.

### Claim 7 (depends on 2)

The method of claim 2 wherein said overlying film comprises Silicon dioxide or Silicon nitride and said base material comprises crystalline Silicon.

### Claim 8

A method of performing atomic layer etching of an overlying film on a workpiece, comprising:
coupling an RF bias voltage to said workpiece;
passivating a predetermined thickness of a layer of said overlying film, comprising introducing into said chamber a gas containing a passivation species and generating a plasma in said chamber for passivation by radiating gas in said chamber with an electron beam having a beam direction parallel to a plane of said workpiece from an electron beam generator;
etching the predetermined thickness of said layer, comprising introducing into said chamber a gas containing an etch species and generating a plasma in said chamber for etching by radiating gas in said chamber with an electron beam having a beam direction parallel to a plane of said workpiece from an electron beam generator;
during said passivating, setting energy of ions in said chamber to a first ion energy level less than a first minimum ion energy for etching said layer by conforming a time domain waveform of said RF bias voltage to an RF waveform in which the RF voltage is at a level corresponding to said first ion energy level for a duration of at least 50% of an RF cycle of said RF waveform;
during said etching, setting energy of ions in said chamber to a second ion energy level exceeding said first minimum ion energy by conforming a time domain waveform of said RF bias voltage to an RF waveform in which the RF voltage is at a level corresponding to said second ion energy level for a duration of at least 50% of an RF cycle of said RF waveform.

### Claim 9 (depends on 8)

The method of claim 8 further comprising:
limiting said passivating to a time duration corresponding to said predetermined thickness.

### Claim 10 (depends on 9)

The method of claim 9 wherein said predetermined thickness corresponds to a predetermined number of atomic layers of said layer.

### Claim 11 (depends on 10)

The method of claim 10 wherein said predetermined thickness corresponds to a single atomic layer.

### Claim 12 (depends on 11)

The method of claim 11 further comprising repeating said passivating and etching in successive operations until removal of said layer is complete.

### Claim 13 (depends on 8)

The method of claim 8 further comprising introducing a passivating process gas during said passivating and introducing an etch process gas during said etching.

### Claim 14

A method of removing an overlying film on a workpiece in a chamber, comprising:
performing alternating operations of passivating and etching;
wherein said passivating comprises: introducing into said chamber a gas containing a passivation species and generating a plasma in said chamber for passivation by radiating gas in said chamber with an electron beam having a beam direction parallel to a plane of said workpiece from an electron beam generator;
wherein said etching comprises: introducing into said chamber a gas containing an etch species and generating a plasma in said chamber for etching by radiating gas in said chamber with an electron beam having a beam direction parallel to a plane of said workpiece from an electron beam generator;
during said passivating, tailoring RF bias power to a waveform in which RF voltage is at a level corresponding to a first ion energy level less than an etch threshold of said overlying film for a duration of at least 50% of an RF cycle of said waveform; and
during said etching, tailoring RF bias power to a waveform in which RF voltage is at a level corresponding to a second ion energy level exceeding an etch threshold of said overlying film for a duration of at least 50% of an RF cycle of said waveform.

### Claim 15 (depends on 14)

The method of claim 14 further comprising:
limiting said passivating to a time duration corresponding to a predetermined thickness of a layer of said overlying film.

### Claim 16 (depends on 15)

The method of claim 15 wherein said predetermined thickness corresponds to an atomic layer.