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US 9,793,127 B2Granted
Plasma generation and pulsed plasma etching
AssigneeTaiwan Semiconductor Manufacturing Company, Ltd.
InventorsYu Chao Lin, Chao-Cheng Chen
Life of this patent
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Abstract
One or more plasma etching techniques are provided. Selective plasma etching is achieved by introducing a gas into a chamber containing a photoresist over a substrate, establishing a bias at a frequency to convert the gas to a plasma at the frequency, and using the plasma to etch the photoresist. The frequency controls an electron density of the plasma and by maintaining a low electron density causes free radicals of the plasma to chemically etch the photoresist, rather than physically etching using ion bombardment. A mechanism is thus provided for chemically etching a photoresist under what are typically physical etching conditions.
Claims19
A method for plasma etching, comprising:
- patterning a photoresist to form a patterned photoresist, wherein the patterning creates an opening through the photoresist and a first sidewall of a first portion of the patterned photoresist and a second sidewall of a second portion of the patterned photoresist below the first portion of the patterned photoresist that together define one side of the opening are tapered;
- and
- treating the first sidewall and the second sidewall while the patterned photoresist is situated between a first electrode and a second electrode in a chamber and while maintaining a temperature within the chamber between about 20° C. to about 120° C., the treating comprising:
- introducing a first gas into the chamber to expose the first sidewall and the second sidewall to the first gas while the chamber is free of plasma;
- and
- after exposing the first sidewall and the second sidewall to the first gas, establishing a bias between the first electrode and the second electrode to convert the first gas to plasma, the bias established according to a frequency and a duty cycle selected based on a specified electron density of the plasma, wherein:
- free radicals of the plasma chemically etch the second sidewall of the patterned photoresist to change a slope of the second sidewall such that the second sidewall is non-tapered after the treating;
- and
- the temperature within the chamber pre-heats the patterned photoresist prior to the establishing a bias to convert the first gas to plasma.
6 more elements
A method for plasma etching, comprising:
- patterning a photoresist to form a patterned photoresist, wherein:
- the patterning creates a first opening and a second opening through the photoresist;
- a first sidewall of the patterned photoresist defines the first opening and a second sidewall of the patterned photoresist defines the second opening;
- in a first portion of the patterned photoresist, the first sidewall is separated from the second sidewall by a first distance;
- in a second portion of the patterned photoresist below the first portion, the first sidewall is separated from the second sidewall by a second distance;
- and
- a difference between the first distance and the second distance is a first absolute value;
- and
- treating the patterned photoresist while the patterned photoresist is situated between a first electrode and a second electrode in a chamber and while maintaining a temperature within the chamber between about 20° C. to about 120° C., the treating comprising:
- introducing a first gas into the chamber to expose the patterned photoresist to the first gas while the first electrode and the second electrode are powered off;
- and
- after exposing the patterned photoresist to the first gas, establishing a bias between the first electrode and the second electrode to convert the first gas to plasma for etching the patterned photoresist, wherein:
- the temperature within the chamber pre-heats the patterned photoresist prior to the establishing a bias to convert the first gas to plasma;
- free radicals of the plasma chemically etch the patterned photoresist;
- and
- the first distance and the second distance are substantially the same after the establishing a bias.
13 more elements
A method for plasma etching, comprising:
- patterning a photoresist to form a patterned photoresist, wherein the patterned photoresist has a line width roughness (LWR);
- and
- treating the patterned photoresist while the patterned photoresist is situated between a first electrode and a second electrode in a chamber and while maintaining a temperature within the chamber between about 20° C. to about 120° C., the treating comprising:
- introducing a first gas into the chamber to expose the patterned photoresist to the first gas while no bias exists between the first electrode and the second electrode;
- and
- establishing a bias of between about 0V to about 50V between the first electrode and the second electrode at a frequency of between about 1 kHz to about 20 kHz to convert the first gas to plasma for etching the patterned photoresist, wherein:
- the temperature within the chamber pre-heats the patterned photoresist prior to the establishing a bias to convert the first gas to plasma;
- the frequency is selected based on a specified electron density of the plasma;
- free radicals of the plasma chemically etch the patterned photoresist such that after the etching a second sidewall of a second portion of the patterned photoresist below a first portion of the patterned photoresist is non-tapered;
- and
- the LWR of the patterned photoresist decreases due to chemically etching the patterned photoresist using the free radicals.
8 more elements
Dependencies are inferred from the claim text.