# US 2014/0190632 A1 · Method and apparatus for photomask plasma etching

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- Number: US 2014/0190632 A1
- Document ID: US20140190632A1
- Status: Published application
- Kind: A1
- Application number: 14/050,224
- Filed: 2013-10-09
- Published: 2014-07-10
- Earliest claimed: 2004-06-30
- Assignees: Applied Materials, Inc.
- Applicants: Applied Materials, Inc.
- Inventors: Ajay KUMAR; Madhavi CHANDRACHOOD; Scott Alan ANDERSON; Peter SATITPUNWAYCHA; Wai-Fan YAU
- Web page: https://patentgrep.com/patent/US20140190632A1

## CPC

- H01J 37/32651: {Shields, e.g. dark space shields, Faraday shields}
- H01J 37/32357: {Generation remote from the workpiece, e.g. down-stream}
- H01J 37/32422: {Arrangement for selecting ions or species in the plasma}
- H01J 37/32623: {Mechanical discharge control means}
- H01J 37/32871: {Means for trapping or directing unwanted particles}
- G03F 1/80: Etching
- H01J 2237/0225: Detecting or monitoring foreign particles
- H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H)
- G03F: PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR; (phototypographic composing devices B41B; photosensitive materials or processes for photographic purposes G03C; electrophotography, sensitive layers or processes therefor G03G)

## Abstract

A method and apparatus for etching photomasks is provided herein. In one embodiment, a method of etching a photomask includes providing a process chamber having a substrate support pedestal adapted to receive a photomask substrate thereon. An ion-radical shield is disposed above the pedestal. A substrate is placed upon the pedestal beneath the ion-radical shield. A process gas is introduced into the process chamber and a plasma is formed from the process gas. The substrate is etched predominantly with radicals that pass through the shield.

## Claims

### Claim 1

An apparatus for plasma etching, comprising:
an inductively coupled plasma process chamber;
an electrostatic substrate support pedestal disposed in the process chamber;
a reticle adapter positioned on the pedestal, the reticle adapter having an opening to receive a photomask reticle;
a co-axial coil positioned proximate the process chamber for inductively coupling power to a plasma formed within the process chamber;
an RF power source coupled to the co-axial coil for forming the plasma within the process chamber;
an ion-radical shield disposed in the process chamber above the pedestal and adapted to control the spatial distribution of charged and neutral species of the plasma; wherein the ion-radical shield comprises a substantially flat member made from quartz, ceramic, or anodized aluminum, the substantially flat member having a plurality of apertures, wherein a plurality of legs are utilized to support the ion-radical shield above the pedestal; and
an edge ring disposed on the reticle adapter and having the plurality of support legs extending therefrom.

### Claim 2 (depends on 1)

The apparatus of claim 1, wherein the plurality of legs supports the ion-radical shield at a distance of 1.5 inches to 4 inches above the pedestal.

### Claim 3 (depends on 1)

The apparatus of claim 1, wherein each of the the plurality of apertures has a diameter of about 1.25 cm.

### Claim 4 (depends on 1)

The apparatus of claim 1, wherein the shield is disposed about 2 inches above the substrate support pedestal.

### Claim 5 (depends on 1)

The apparatus of claim 1, wherein the substantially flat member is electrically isolated from the chamber.

### Claim 6 (depends on 5)

The apparatus of claim 5, wherein the substantially flat member comprises a plate having the plurality of apertures formed therethrough.

### Claim 7 (depends on 6)

The apparatus of claim 6, wherein the apertures are arranged in a square grid pattern.

### Claim 8 (depends on 1)

The apparatus of claim 1, wherein the legs support the plate in a substantially parallel, spaced apart relation with respect to the pedestal.

### Claim 9 (depends on 6)

The apparatus of claim 6, wherein each of the plurality of legs is secured to an underside of the plate.

### Claim 10 (depends on 1)

The apparatus of claim 1, wherein the ion-radical shield comprise a plurality of apertures for defining an open area of the plate from about 2 percent to about 90 percent.

### Claim 11

An apparatus for plasma etching, comprising:
a process chamber;
a substrate support pedestal disposed in the process chamber and having an opening adapted to receive a photomask reticle;
an RF power source;
an antenna comprising a co-axial coil positioned to inductively couple power from the RF power source to a plasma within the process chamber; and
an ion-radical shield for controlling the spatial distribution of charged and neutral species of the plasma, wherein said ion-radical shield further comprises:
a substantially flat member having an areal extent larger than an areal extent of the substrate support pedestal;
a plurality of apertures formed through the member and configured to promote center fast etching; and
a plurality of legs secured to the member above the substrate support pedestal, wherein the legs do not extend beyond the areal extent of the member.

### Claim 12 (depends on 11)

The apparatus of claim 11, wherein the substantially flat member comprises quartz, ceramic, or anodized aluminum.

### Claim 13 (depends on 12)

The apparatus of claim 12, wherein the plurality of apertures have size, spacing and geometric arrangement that vary across the ion-radical shield.

### Claim 14 (depends on 13)

The apparatus of claim 13, wherein the ion-radical shield has an areal extent larger than an areal extent of the substrate support pedestal.

### Claim 15

An apparatus for plasma etching, comprising:
a process chamber having a conductive body and a dielectric ceiling;
a substrate support pedestal disposed in the process chamber, the substrate support having a reticle adapter with an opening substantially centered with respect to the pedestal;
an RF power source;
a co-axial antenna positioned to inductively couple power from the RF power source to a plasma within the process chamber; and
an ion-radical shield disposed in the chamber above the pedestal and comprising a plurality of apertures adapted to control the spatial distribution of charged and neutral species of the plasma; wherein the ion-radical shield has an areal extent larger than an areal extent of the substrate support pedestal, wherein a plurality of legs are secured to the ion-radical shield and support the ion-radical shield a distance of about 1.5 inches (3.81 cm) to about 4 inches (10.16 cm) above the pedestal.

### Claim 16 (depends on 15)

The apparatus of claim 15, wherein the plurality of legs are disposed within a volume defined between the ion-radical shield and the substrate support pedestal.

### Claim 17 (depends on 15)

The apparatus of claim 15, wherein the plurality of apertures define an open area of about 30 percent.

### Claim 18 (depends on 15)

The apparatus of claim 15, wherein the plurality of apertures have size, spacing and geometric arrangement that vary across the ion-radical shield.

### Claim 19 (depends on 15)

The apparatus of claim 15, wherein the ion-radical shield is fabricated from at least one of ceramic, quartz, or anodized aluminum.

### Claim 20

An apparatus for plasma etching, comprising:
an inductively coupled plasma process chamber;
a substrate support pedestal disposed in the process chamber, the substrate support comprising a cathode and a reticle adapter covering an upper surface of the cathode having a top portion with an opening to receive a photomask reticle;
an RF power source for forming a plasma within the chamber;
an ion-radical shield disposed in the chamber above the pedestal and comprising a plurality of apertures arranged in a square grid pattern for controlling a spatial distribution of charged and neutral species of the plasma, wherein the ion-radical shield is fabricated from anodized aluminum and has an areal extent larger than an areal extent of the photomask reticle;
a plurality of legs extending from the substrate support pedestal and secured to the ion-radical shield, wherein the legs do not extend beyond the areal extent of the ion-radical shield, wherein the ion-radical shield has a height relative to the pedestal that controls etch rate during plasma processing and the height is set by the legs utilized to support the ion-radical shield above the pedestal, wherein the height is between about 1.5 inches (3.81 cm) to about 4 inches (10.16 cm) in a process chamber having a distance of about 6 inches between the pedestal and a ceiling of the process chamber; and
an edge ring disposed on the reticle adapter and having the plurality of legs extending therefrom.