# US 12,119,243 B2 · Plasma etching chemistries of high aspect ratio features in dielectrics

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- Number: US 12,119,243 B2
- Document ID: US12119243B2
- Status: Granted
- Kind: B2
- Application number: 18/163,522
- Filed: 2023-02-02
- Published: 2023-06-15
- Granted: 2024-10-15
- Earliest claimed: 2018-03-16
- Assignees: Lam Research Corporation
- Applicants: Lam Research Corporation
- Inventors: Keren J. Kanarik; Samantha Siamhwa Tan; Yang Pan; Jeffrey Marks
- Web page: https://patentgrep.com/patent/US12119243B2

## CPC

- H10P 50/283: {by chemical means}
- H10P 72/0421: {for drying etching}
- H10P 50/73: {using masks for insulating materials}
- H10P 72/0434: {mainly by convection}
- H10P 72/0602: {Temperature monitoring}
- H10P 72/72: using electrostatic chucks
- H10P 72/722: {Details of electrostatic chucks}
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

A method for etching features in a stack below a patterned mask in an etch chamber is provided. The stack is cooled with a coolant with a coolant temperature below −20° C. An etch gas is flowed into the etch chamber. A plasma is generated from the etch gas. Features are selectively etched into the stack with respect to the patterned mask.

## Claims

### Claim 1

A method for etching a stack, comprising:
a) cooling the stack to a temperature below −20° C.;
b) flowing an etch gas into the etch chamber, wherein the etch gas comprises at least one of SiF4, TaF5, BrF5, AsF5, NF5, PF5, NbF5, BiF5, UF5, SiCl2, CrO2Cl2, TaCl4, HfCl4, TiCl3(1), CoCl2(1), TiCl3, CCl4, CBr2F2, C2F5Br, H2O, H2O2, BCl3, NH3, SiF4, CrO2Cl2, SiCl4, TiCl2, TiCl3, CoCl2, and TiCl2;
c) generating a plasma from the etch gas; and
d) selectively etching features in the stack with respect to a patterned mask, wherein the stack is comprised of alternating layers of silicon oxide and polysilicon.

### Claim 2 (depends on 1)

The method, as recited in claim 1, further comprising providing a bias with a magnitude of at least 400 volts.

### Claim 3 (depends on 1)

The method, as recited in claim 1, wherein the etch gas is oxygen free.

### Claim 4 (depends on 1)

The method, as recited in claim 1, wherein the stack is cooled to a temperature below −60° C.

### Claim 5 (depends on 1)

The method, as recited in claim 1, wherein the stack is cooled to a temperature in the range of −20° C. to −60° C.