# US 9,520,259 B2 · Ion beam uniformity control

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- Number: US 9,520,259 B2
- Document ID: US9520259B2
- Status: Granted
- Kind: B2
- Application number: 14/949,468
- Filed: 2015-11-23
- Published: 2016-04-21
- Granted: 2016-12-13
- Earliest claimed: 2014-10-16
- Assignees: Varian Semiconductor Equipment Associates, Inc.
- Applicants: Varian Semiconductor Equipment Associates, Inc.
- Inventors: Alexandre Likhanskii; Svetlana B. Radovanov; Bon-Woong Koo
- Web page: https://patentgrep.com/patent/US9520259B2

## CPC

- H01J 27/024: {Extraction optics, e.g. grids}
- H01J 37/08: Ion sources; Ion guns
- H01J 27/16: using high-frequency excitation, e.g. microwave excitation
- H01J 2237/0815: Methods of ionisation
- H05H 1/4652: {using inductive coupling means, e.g. coils}
- H05H 1/466: {using capacitive coupling means, e.g. electrodes}
- H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H)
- H05H: PLASMA TECHNIQUE (apparatus or processes specially adapted for producing X-rays H05G2/00); PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS

## Abstract

A plasma chamber having improved controllability of the ion density of the extracted ribbon ion beam is disclosed. A plurality of pairs of RF biased electrodes is disposed on opposite sides of the extraction aperture in a plasma chamber. In some embodiments, one of each pair of RF biased electrodes is biased at the extraction voltage, while the other of each pair is coupled to a RF bias power supply, which provides a RF voltage having a DC component and an AC component. In another embodiment, both of the electrodes in each pair are coupled to a RF biased power supply. A blocker may be disposed in the plasma chamber near the extraction aperture. In some embodiments, RF biased electrodes are disposed on the blocker.

## Claims

### Claim 1

A plasma chamber, comprising:
a power source to generate a plasma within the plasma chamber;
a chamber wall having an extraction aperture through which ions from the plasma are extracted, the chamber wall biased at an extraction voltage;
a blocker disposed within the plasma chamber proximate the extraction aperture, biased at the extraction voltage;
an RF biased electrode disposed on the blocker; and
an RF bias power supply to supply a RF voltage to the RF biased electrode.

### Claim 2 (depends on 1)

The plasma chamber of claim 1, wherein the RF voltage comprises a DC component and an AC component and the DC component is equal to the extraction voltage.

### Claim 3 (depends on 1)

The plasma chamber of claim 1, further comprising a plurality of RF biased electrodes disposed on the blocker along a length of the extraction aperture.

### Claim 4 (depends on 3)

The plasma chamber of claim 3, wherein each of the plurality of RF biased electrodes is separately powered by the RF bias power supply.

### Claim 5 (depends on 1)

The plasma chamber of claim 1, wherein a power level of the RF voltage determines an angle of incidence of ions passing between the blocker and the chamber wall.

### Claim 6

A plasma chamber, comprising:
a power source to generate a plasma within the plasma chamber;
a chamber wall having an extraction aperture through which ions from the plasma are extracted, the chamber wall biased at an extraction voltage;
a blocker disposed within the plasma chamber proximate the extraction aperture;
an RF biased electrode disposed on the blocker; and
an RF bias power supply to supply a RF voltage to the RF biased electrode.

### Claim 7 (depends on 6)

The plasma chamber of claim 6, wherein the blocker comprises a dielectric material.

### Claim 8 (depends on 6)

The plasma chamber of claim 6, wherein the RF biased electrode is disposed on a top surface of the blocker, defined as a surface furthest away from the extraction aperture.

### Claim 9 (depends on 6)

The plasma chamber of claim 6, wherein the RF biased electrode is disposed on a bottom surface of the blocker, defined as a surface closest to the extraction aperture.

### Claim 10 (depends on 6)

The plasma chamber of claim 6, further comprising a second RF biased electrode wherein the RF biased electrode and the second RF biased electrode are disposed on opposite sides of the blocker.

### Claim 11 (depends on 6)

The plasma chamber of claim 6, wherein the blocker comprises a conductive material.

### Claim 12 (depends on 6)

The plasma chamber of claim 6, further comprising a pair of RF biased electrodes disposed on an interior of the chamber wall on opposite sides of the extraction aperture.

### Claim 13 (depends on 6)

The plasma chamber of claim 6, wherein the RF voltage comprises a DC component and an AC component and the DC component is equal to the extraction voltage.

### Claim 14 (depends on 6)

The plasma chamber of claim 6, further comprising a plurality of RF biased electrodes disposed on the blocker along a length of the extraction aperture.

### Claim 15 (depends on 14)

The plasma chamber of claim 14, wherein each of the plurality of RF biased electrodes is separately powered by the RF bias power supply.

### Claim 16

A plasma chamber, comprising:
a power source to generate a plasma within the plasma chamber;
a chamber wall having an extraction aperture through which ions from the plasma are extracted, the chamber wall biased at an extraction voltage;
a blocker, comprising a conductive material, disposed within the plasma chamber proximate the extraction aperture; and
an RF bias power supply to supply a RF voltage to the blocker.

### Claim 17 (depends on 16)

The plasma chamber of claim 16, wherein the RF voltage comprises a DC component and an AC component and the DC component is equal to the extraction voltage.