Back to results
US 8,273,259 B1Granted
Ashing method
AssigneeNovellus Systems, Inc.
InventorsHuatan Qiu, David Wingto Cheung
Life of this patent
Estimating the term…
Abstract
Ashing of organic material is conducted initially at a low temperature and then at a high temperature. A low flow rate of ashing gas maximizes ashing rate at the low temperature, and a high flow rate of ashing gas maximizes ashing rate at a high temperature. Preferably, a crossover temperature of a particular organic material in a given ashing system is determined, the crossover temperature characterized in that below the crossover temperature, a decrease in ashing gas flow rate results in an increase of ashing rate, and above the crossover temperature, an increase in ashing gas flow rate results in an increase of ashing rate.
Claims36
A method of determining a crossover temperature of a type of organic material in an ashing system, comprising:
- (a) heating a test sample of a type of organic material at a test temperature in an ashing chamber;
- (b) flowing ashing gas to a remote plasma generator;
- (c) generating activated ashing species in said ashing gas using said remote plasma generator;
- (d) flowing activated ashing gas containing said activated ashing species into said ashing chamber at a test flow rate;
- (e) ashing a portion of said test sample in said ashing chamber at said test temperature and at said test flow rate using said activated ashing species;
- (f) measuring an ashing time used to ash said portion of said test sample;
- (g) measuring an amount of said portion of said test sample that was ashed;
- and
- (h) calculating a measured ashing rate corresponding to said test temperature and said test flow rate based on said ashing time used to ash said amount of said portion of said test sample that was ashed;
- (i) repeating (a) through (h) using at least one test sample of said type of organic material at a plurality of different combinations of test temperatures and test flow rates to calculate a plurality of measured ashing rates;
- and
- (j) determining a crossover temperature of said type of organic material in said ashing system by comparing said measured ashing rates, wherein said crossover temperature is characterized in that below said crossover temperature, a decrease in test flow rate results in an increase of measured ashing rate, and above said crossover temperature, an increase in test flow rate results in an increase of measured ashing rate.
9 more elements
A method of minimizing total ashing time of organic material in an ashing system, comprising:
- (a) heating in a low-temperature ashing chamber a substrate containing an initial layer of organic material at a low temperature below a crossover temperature of said organic material in an ashing system, wherein said crossover temperature is characterized in that below said crossover temperature, a decrease in test flow rate results in an increase of measured ashing rate, and above said crossover temperature, an increase in test flow rate results in an increase of measured ashing rate;
- (b) flowing a first ashing gas to a first remote plasma generator;
- (c) generating first activated ashing species in said first ashing gas using said first remote plasma generator;
- (d) flowing first activated ashing gas containing said first activated ashing species into said low-temperature ashing chamber at a low flow rate;
- (e) ashing an initial portion of said layer of organic material at said low temperature and at said low flow rate using said first activated ashing species in said low-temperature ashing chamber;
- (f) heating said substrate in a high-temperature ashing chamber at a high temperature above said crossover temperature of said organic material in said ashing system;
- (g) flowing a second ashing gas to one of said first remote plasma generator and a second remote plasma generator;
- (h) generating a second activated ashing species in said second ashing gas using said one of said first remote plasma generator and said second remote plasma generator;
- (i) flowing said second activated ashing gas containing said second activated ashing species into said high-temperature ashing chamber at a high flow rate;
- and
- (j) ashing an additional portion of said organic material at said high temperature and at said high flow rate using said second activated ashing species in said high-temperature ashing chamber.
8 more elements
A method of minimizing total ashing time of organic material in an ashing system, comprising:
- (a) heating a substrate containing organic material at a low temperature in a low-temperature ashing chamber;
- (b) flowing a first ashing gas to a first remote plasma generator;
- (c) generating a first activated ashing species in said first ashing gas using said first remote plasma generator;
- (d) flowing a first activated ashing gas containing said first activated ashing species into said low-temperature ashing chamber at a low flow rate;
- (e) ashing an initial portion of said organic material at said low temperature and at said low flow rate using said first activated ashing species in said low-temperature ashing chamber;
- (f) heating said substrate at a high temperature in a high-temperature ashing chamber;
- (g) flowing a second ashing gas to one of said first remote plasma generator and a second remote plasma generator;
- (h) generating a second activated ashing species in said ashing gas using said one of said first remote plasma generator and said second remote plasma generator;
- (i) flowing a second activated ashing gas containing said second activated ashing species into said high-temperature ashing chamber at a high flow rate;
- and
- (j) ashing an additional portion of said organic material at said high temperature and at said high flow rate using said second activated ashing species in said high-temperature ashing chamber.
8 more elements
A method of minimizing total ashing time of organic material in an ashing system, comprising:
- (a) heating a substrate containing organic material at a high temperature in a high-temperature ashing chamber;
- (b) flowing a first ashing gas to a first remote plasma generator;
- (c) generating a first activated ashing species in said first ashing gas using said first remote plasma generator;
- (d) flowing a first activated ashing gas containing said first activated ashing species into said high-temperature ashing chamber at a high flow rate;
- (e) ashing an initial portion of said organic material at said high temperature and at said high flow rate using said first activated ashing species in said high-temperature ashing chamber;
- (f) heating said substrate at a low temperature in a low-temperature ashing chamber;
- (g) flowing a second ashing gas to one of said first remote plasma generator and a second remote plasma generator;
- (h) generating a second activated ashing species in said second ashing gas using said one of said first remote plasma generator and said second remote plasma generator;
- (i) flowing said second activated ashing gas containing said second activated ashing species into said low-temperature ashing chamber at a low flow rate;
- and
- (j) ashing an additional portion of said organic material at said low temperature and at said low flow rate using said second activated ashing species in said low-temperature ashing chamber.
8 more elements
Dependencies are inferred from the claim text.