Systems and methods for determining residual compounds in plasma process
The present disclosure provides a system and method for predicting wafer fabrication defects resulting from plasma processing of wafers in a plasma processing chamber. The system and method include processing electromagnetic signals emitted from residual compounds peeled from the chamber walls during the plasma processing of the wafers to indirectly determine the likelihood that the wafers are incurring fabrication processing defects during the plasma processing.
1 . A method for carrying out a plasma process on a semiconductor substrate in a plasma processing chamber, comprising:
performing plasma processing of the semiconductor substrate, the plasma process including a plurality of processing steps;
receiving, over a time period, electromagnetic signals emitted by one or more residual compounds in the plasma processing chamber during plasma processing of the semiconductor substrate in the plasma processing chamber, the signals having corresponding wavelengths;
processing the received electromagnetic signals to generate predictive signals from the received electromagnetic signals, wherein processing the received electromagnetic signals includes integrating and normalizing the electromagnetic signals over the time period;
analyzing the predictive signals over the time period;
predicting presence of fabrication defects on the semiconductor substrate based on the analyzing of the predictive signals over the time period, wherein predicting includes comparing the predictive signals to predefined thresholds for percentage changes between consecutively integrated intensities of the predictive signals;
modifying a parameter of one processing step of the plurality of processing steps of the plasma process based on the results of the predicting presence of fabrication defects on the semiconductor substrate; and
continuing to perform the processing step of the plasma process with the modified parameter.
2 . The method of claim 1 , further comprising:
generating one or more control signals based on the analyzing the predictive signals over the time period; and
regulating a flow of one or more active gases into the plasma processing chamber based on the one or more control signals, wherein the parameter is a flowrate of the flow.
3 . The method of claim 1 , wherein the received electromagnetic signals have corresponding wavelengths chosen from at least one of 425 nm, 520 nm, 655 nm, 750 nm, 822 nm and 830 nm.
4 . The method of claim 1 , wherein the modified parameter includes one or more of gas flow rate, RF power, or processing time.
5 . The method of claim 1 , wherein the predefined thresholds for percentage changes between consecutively integrated intensities of the predictive signals is between 3% and 10%.
6 . The method of claim 1 , wherein the plasma processing of the semiconductor substrate in the plasma processing chamber is a dry etch, and the fabrication defects include incomplete etching of patterns in the semiconductor substrate caused by presence of the one or more residual compounds in trenches etched in the semiconductor substrate.
7 . The method of claim 1 , wherein the performing plasma processing utilizes active gases and the active gases are one or more of sulfur hexafluoride, carbon tetrafluoride, trifluoro methane, chlorine, boron trichloride, hydrogen bromide and octafluorocyclobutane.
8 . A method for carrying out a plasma process on a semiconductor wafer in a plasma processing chamber, comprising:
performing plasma processing of the wafer;
receiving, over a time period, a plurality of electromagnetic signals emitted by one or more residual compounds in the plasma processing chamber during plasma processing of the semiconductor wafer in the plasma processing chamber, the plurality signals having corresponding wavelengths;
analyzing the plurality of received electromagnetic signals by integrating and normalizing the electromagnetic signals over the time period, including:
grouping the plurality of electromagnetic signals into groups based on their corresponding wavelengths; and
generating a plurality of predictive data, wherein the predictive data includes one or more of peak intensities, duration, intensity patterns, or correlation to other wavelengths;
predicting presence of the one or more residual compounds in the plasma processing chamber based on the analyzing of the received electromagnetic signals by comparing the predictive data to predefined thresholds for percentage changes between consecutively integrated intensities of the predictive data;
stopping the plasma process based on the results of the predicting presence of the one or more residual compounds in the plasma processing chamber; and
cleaning the plasma processing chamber after the stopping the plasma process has occurred to remove the one or more residual compounds from the plasma processing chamber.
9 . The method of claim 8 , further comprising initiating a quality control procedure that indicates that a risk of processing-induced defects for the semiconductor wafer has increased.
10 . The method of claim 8 , wherein the cleaning the plasma processing chamber removes precursors of the residual compounds from a surface of an injector port coupled to the plasma processing chamber or an exhaust port coupled to the plasma processing chamber.
11 . The method of claim 8 , wherein analyzing the plurality of received electromagnetic signals further comprises filtering the electromagnetic signals over the time period.
12 . The method of claim 8 , wherein the predefined thresholds for percentage changes between consecutively integrated intensities of the predictive data is 10%.
13 . The method of claim 8 , wherein the predefined thresholds for percentage changes between consecutively integrated intensities of the predictive data is 3%.
14 . The method of claim 8 , wherein the received electromagnetic signals have corresponding wavelengths chosen from at least one of 425 nm, 520 nm, 655 nm, 750 nm, 822 nm and 830 nm.
15 . The method of claim 8 , wherein the plasma processing includes dry etching, physical vapor deposition or chemical vapor deposition.
16 . A method for carrying out a plasma process on a semiconductor wafer in a plasma processing chamber, comprising:
performing plasma processing of the wafer using a flow of one or more active gases, the flow having a rate of flow;
receiving at an optical emission spectrometer through a window in the plasma processing chamber, over a period of time, electromagnetic signals emitted by one or more residual compounds in the plasma processing chamber during plasma processing of the semiconductor wafer in the plasma processing chamber, the signals having corresponding wavelengths;
analyzing the received electromagnetic signals by integrating and normalizing the signals over the time period, and predicting presence of fabrication defects based on the analyzing, wherein predicting includes comparing the integrated and normalized signals to predefined thresholds for percentage changes between consecutively integrated intensities of the signals;
generating one or more control signals based on the analyzing of the received electromagnetic signals, wherein the control signals are configured to adjust the rate of flow of the one or more active gases;
maintaining the flow of the one or more active gases into the plasma processing chamber at an alternative rate based on the generated one or more control signals to mitigate a risk of the semiconductor wafer incurring fabrication defects; and
adjusting the flow rate of the active gases in real-time based on continuous monitoring and analysis of the received electromagnetic signals.
17 . The method of claim 16 , further comprising inspecting the semiconductor wafer to check for any fabrication defects.
18 . The method of claim 16 , wherein the received electromagnetic signals have corresponding wavelengths chosen from at least one of 425 nm, 520 nm, 655 nm, 750 nm, 822 nm and 830 nm.
19 . The method of claim 16 , wherein the performing plasma processing utilizes active gases and the active gases are one or more of sulfur hexafluoride, carbon tetrafluoride, trifluoro methane, chlorine, boron trichloride, hydrogen bromide and octafluorocyclobutane.
20 . The method of claim 16 , wherein the plasma processing includes dry etching, physical vapor deposition or chemical vapor deposition.