# US 9,039,908 B2 · Post etch reactive plasma milling to smooth through substrate via sidewalls and other deeply etched features

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- Number: US 9,039,908 B2
- Document ID: US9039908B2
- Status: Granted
- Kind: B2
- Application number: 12/229,946
- Filed: 2008-08-27
- Published: 2010-03-04
- Granted: 2015-05-26
- Earliest claimed: 2008-08-27
- Assignees: Applied Materials, Inc.
- Applicants: Jon Farr; Sharma Pamarthy; Khalid Sirajuddin
- Inventors: Jon Farr; Sharma Pamarthy; Khalid Sirajuddin
- Web page: https://patentgrep.com/patent/US9039908B2

## CPC

- H10P 50/242: {of Group IV materials}
- H01J 37/321: {the radio frequency energy being inductively coupled to the plasma}
- H01J 37/32146: {Amplitude modulation, includes pulsing}
- H10P 50/287: {by chemical means}
- H10P 70/20: {Cleaning during device manufacture}
- H10W 20/023: {the interconnections being through-semiconductor vias}
- H10W 20/0245: {comprising use of blind vias during the manufacture}
- H10W 20/081: {by forming openings in the dielectric parts}
- Y10T 428/24479: including variation in thickness
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H)
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

A method of smoothing the sidewalls of an etched feature using reactive plasma milling. The method of smoothing reduces the depth of sidewall notching, which causes the roughness on the feature wall surface. The method comprises removing residual polymeric materials from the interior and exterior surfaces of said silicon-comprising feature and treating the interior surface of the silicon-comprising feature with a reactive plasma generated from a source gas while the silicon-comprising feature is biased with a pulsed RF power. The source gas includes a reagent which reacts with the silicon and an inert gas. The method provides a depth of a notch on the interior surface of about 500 nm or less.

## Claims

### Claim 1

A method of reactive plasma milling to smooth an interior surface of a silicon-comprising feature subsequent to etching of the feature, said method comprising:
removing residual polymeric materials from an interior surface of an etched silicon-comprising feature; followed by
treating said interior surface of said etched silicon-comprising feature with a reactive plasma generated from a source gas which includes a reagent which reacts with silicon and an inert gas, while a substrate comprising said silicon-comprising feature is biased with a pulsed RF power, and wherein a pulsing frequency ranges from about 10 Hz to about 1000 Hz and a duty time % ranges from about 2% to about 40%, so that a milled interior surface of said etched silicon-comprising feature has a depth of notch of 700 nm or less.

### Claim 2 (depends on 1)

A method in accordance with claim 1, wherein said reactive plasma is generated using about 10 kHz to about 60 MHZ RF power and said substrate biasing is carried out using 10 kHz to about 13.56 MHZ RF power.

### Claim 3 (depends on 1)

A method in accordance with claim 1, wherein said substrate comprising said feature is biased with a pulsed RF power where the pulsing frequency ranges from about 50 Hz to about 180 Hz and the duty time % ranges from 5% to 30%.

### Claim 4 (depends on 3)

A method in accordance with claim 3, wherein said treating of said interior surface of said etched feature is carried out for a time period sufficient to reduce a depth of notch on said interior surface of said silicon-comprising etched feature to a depth of 300 nm or less.

### Claim 5 (depends on 4)

A method in accordance with claim 4, wherein said depth of notch after treatment ranges from 5 nm to about 100 nm.

### Claim 6 (depends on 1)

A method in accordance with claim 1, wherein said etched feature is a via and wherein a profile of said via is simultaneously altered while said interior surface of said via is smoothed.

### Claim 7 (depends on 6)

A method in accordance with claim 6, wherein said profile is altered by selecting of a composition of an inert gas which is used to bombard said interior surface during said treating of said interior surface.

### Claim 8 (depends on 5, 6)

A method in accordance with claim 5 or claim 6, wherein said profile is altered by selecting a pressure in a process chamber in which said treating of said interior surface is carried out.

### Claim 9 (depends on 1)

A method in accordance with claim 1, wherein, subsequent to removing said residual polymeric material, and prior to treating said interior surface of said silicon-comprising feature with said reactive plasma, polymeric material is removed surrounding an opening to said silicon-comprising feature.

### Claim 10

A method of smoothing an interior sidewall surface of a previously etched opening which passes through a silicon-comprising substrate, said method comprising:
removing any residual photoresist from an exterior substrate surface through which said opening was etched; and
removing residual protective polymeric material which was deposited on said interior sidewall surface of said opening during etching of said opening; followed by
treating said interior sidewall surface of said previously etched opening with a reactive plasma generated from a source gas which includes a reagent which reacts with silicon and an inert gas, while said silicon-comprising substrate is biased with a pulsed RF power, and wherein said pulsing frequency ranges from about 10 Hz to about 1000 Hz and the duty time % ranges from 2% to 50% so that a smoothed interior sidewall surface of said previously etched opening has a depth of notch of 700 nm or less.

### Claim 11 (depends on 10)

A method in accordance with claim 10, wherein said substrate comprising said opening is biased with a pulsed RF power where the pulsing frequency ranges from about 50 Hz to about 180 Hz and the duty time % ranges from 5% to 30%.

### Claim 12 (depends on 11)

A method in accordance with claim 11, wherein the RF power frequency used to bias said substrate ranges from about 200 kHz to about 2,000 kHz.

### Claim 13 (depends on 11)

A method in accordance with claim 11, wherein said treating of said interior sidewall surface of said etched opening is carried out for a time period sufficient to reduce a depth of notch on said interior sidewall surface to a depth of 300 nm or less.

### Claim 14 (depends on 13)

A method in accordance with claim 13, wherein said depth of notch after treatment ranges from 5 nm to about 100 nm.

### Claim 15 (depends on 10)

A method in accordance with claim 10, wherein, subsequent to removing any residual photoresist and any residual protective polymeric materials from said interior sidewall surface of said opening, and prior to treating said interior sidewall surface of said silicon-comprising etched opening with a smoothing reactive plasma, polymeric material is removed surrounding an entryway to said previously etched opening.

### Claim 16 (depends on 1)

A method in accordance with claim 1, wherein there is residual photoresist present on an exterior surface of said silicon comprising feature, and wherein said residual photoresist is removed in addition to removing said residual polymeric materials from said interior surface of said etched silicon-comprising feature, followed by treating of said interior surface of said etched silicon-comprising feature.