# US 2020/0402801 A1 · Eliminating yield impact of stochastics in lithography

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- Number: US 2020/0402801 A1
- Document ID: US20200402801A1
- Status: Published application
- Kind: A1
- Application number: 17/008,095
- Filed: 2020-08-31
- Published: 2020-12-24
- Earliest claimed: 2017-05-16
- Assignees: Lam Research Corporation
- Applicants: Lam Research Corporation
- Inventors: Nader Shamma; Richard Wise; Jengyi Yu; Samantha Tan
- Web page: https://patentgrep.com/patent/US20200402801A1

## CPC

- H10P 76/4088: {Processes for improving the resolution of the masks}
- H10P 72/32: {between different workstations}
- H10P 76/405: {characterised by their composition, e.g. multilayer masks}
- H10P 76/4083: {characterised by their behaviours during the lithography processes, e.g. soluble masks or redeposited masks}
- H10P 76/4085: {characterised by the processes involved to create the masks}
- H10P 14/6336: {in the presence of a plasma [PECVD]}
- H10P 14/6902: {composed of carbon, e.g. alpha-C, diamond or hydrogen doped carbon}
- H10P 50/285: {of materials not containing Si, e.g. PZT or Al2O3}
- H10P 50/287: {by chemical means}
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

Methods and apparatuses for performing cycles of aspect ratio dependent deposition and aspect ratio independent etching on lithographically patterned substrates are described herein. Methods are suitable for reducing variation of feature depths and/or aspect ratios between features formed and partially formed by lithography, some partially formed features being partially formed due to stochastic effects. Methods and apparatuses are suitable for processing a substrate having a photoresist after extreme ultraviolet lithography. Some methods involve cycles of deposition by plasma enhanced chemical vapor deposition and directional etching by atomic layer etching.

## Claims

### Claim at position 1

-34. (canceled)

### Claim 35

A method of processing semiconductor substrates, the method comprising:
providing a substrate having a patterned photoresist, the patterned photoresist comprising a first feature and a second feature, wherein the first feature is partially defined and comprises photoresist at a bottom of the first feature;
after providing the substrate, preferentially depositing carbon-containing material on the photoresist such that more carbon-containing material is deposited at a bottom of the second feature than at the bottom of the first feature; and
after depositing the carbon-containing material, performing atomic layer etching on exposed surfaces of the substrate.

### Claim 36 (depends on 35)

The method of claim 35, wherein the atomic layer etching is performed by: exposing the exposed surfaces of the substrate to an etching species and igniting a plasma while applying a bias to modify a surface of the exposed surfaces of the substrate and formed a modified surface, and exposing the modified surface to a second plasma for a duration sufficient to remove the modified surface.

### Claim 37 (depends on 36)

The method of claim 36, wherein a bias is applied when exposing the modified surface to the second plasma.

### Claim 38 (depends on 36)

The method of claim 36, wherein the modified surface are etched without sputtering material underlying the modified surface.

### Claim 39 (depends on 36)

The method of claim 36, wherein exposing the exposed surfaces of the substrate to the etching species further comprises introducing a diluent inert gas selected from the group consisting of helium, argon, neon, krypton, and xenon.

### Claim 40 (depends on 35)

The method of claim 35, wherein the substrate further comprises an underlayer adjacent to, and underlying the photoresist, and the carbon-containing material is preferentially deposited so as not to deposit on exposed regions of the underlayer.

### Claim 41 (depends on 35)

The method of claim 35, wherein the carbon-containing material selectively deposited on the photoresist has a slower etch rate than the photoresist when exposed to the atomic layer etching.

### Claim 42 (depends on 35)

The method of claim 35, wherein etch rate of the photoresist during atomic layer etching is faster than etch rate of the carbon-containing material.

### Claim 43 (depends on 35)

The method of claim 35, wherein the atomic layer etching removes photoresist anisotropic ally.

### Claim 44 (depends on 35)

The method of claim 35, wherein deposition thickness in the first and second features is dependent on aspect ratio of the first and second features.

### Claim 45 (depends on 35)

The method of claim 35, wherein the photoresist is patterned by deep ultraviolet lithography.

### Claim 46 (depends on 35)

The method of claim 35, wherein the photoresist is patterned by extreme ultraviolet lithography.

### Claim 47 (depends on 35)

The method of claim 35, wherein the photoresist is patterned by immersion lithography.

### Claim 48 (depends on 47)

The method of claim 47, wherein the immersion lithography involves exposing the photoresist to argon fluoride.

### Claim 49 (depends on 35)

The method of claim 35, wherein preferentially depositing the carbon-containing material on the photoresist on the substrate further comprises introducing methane.

### Claim 50 (depends on 35)

The method of claim 35, wherein preferentially depositing and performing atomic layer etching are repeated in cycles until the first feature has the same critical dimension as the second feature.

### Claim 51

A method of processing semiconductor substrates, the method comprising:
providing a substrate having a patterned photoresist, the patterned photoresist comprising a first feature and a second feature, wherein feature depth of the first feature is less than thickness of the patterned photoresist;
after providing the substrate, depositing carbon-containing material over the patterned photoresist by plasma enhanced chemical vapor deposition; and
after depositing the carbon-containing material, etching the substrate by modifying a surface of exposed surfaces on the substrate to form modified surfaces and etching the modified surfaces.

### Claim 52 (depends on 51)

The method of claim 51, further comprising prior to providing the substrate, forming the patterned photoresist by extreme ultraviolet lithography.

### Claim 53 (depends on 51)

The method of claim 51, further comprising repeating the depositing and the etching in cycles such that each cycle causes the feature depth of the first feature to approach the thickness of the patterned photoresist.

### Claim 54

An apparatus for processing semiconductor substrates, the apparatus comprising:
one or more process chambers, each process chamber comprising a chuck;
one or more gas inlets into the process chambers and associated flow control hardware;
a plasma generator; and
a controller having at least one processor and a memory, wherein
the at least one processor and the memory are communicatively connected with one another,
the at least one processor is at least operatively connected with the flow control hardware, and
the memory stores computer executable instructions for controlling the at least one processor to at least control the flow control hardware by:
causing introduction of a hard mask deposition precursor;
after introducing the hard mask deposition precursor, causing stopping of the introduction of the hard mask deposition precursor;
after stopping the introduction of the hard mask deposition precursor, causing introduction of a modification gas; and
after introduction of the modification gas, causing introduction of an inert gas and generation of a plasma,
wherein introduction of the hard mask deposition precursor, modification gas, and inert gas are performed without breaking vacuum.

### Claim 55 (depends on 54)

The apparatus of claim 54, wherein the apparatus further comprises instructions for repeating introduction of the hard mask deposition precursor, modification gas, and inert gas in two or more cycles.