Feedback loop for controlling a pulsed voltage waveform
Embodiments of this disclosure describe a feedback loop that can be used to maintain a nearly constant sheath voltage and thus creating a mono-energetic IEDF at the surface of the substrate. The system described herein consequently enables a precise control over the shape of IEDF and the profile of the features formed in the surface of the substrate.
1 . A method comprising:
receiving, via a first input channel of a data acquisition system connected to a substrate processing chamber, one or more waveform characteristics of a input voltage waveform;
determining, via a controller, one or more control parameters based on the one or more waveform characteristics and one or more target characteristics; and
transmitting, via the controller, information relating to the one or more control parameters to a pulsed voltage waveform generator electrically coupled to the substrate processing chamber, wherein the transmitted information related to the one or more control parameters provides an indication to adjust a pulsed voltage waveform established by the pulsed voltage waveform generator.
2 . The method of claim 1 , wherein the one or more target characteristics are received by the controller from a memory.
3 . The method of claim 1 , wherein the one or more target characteristics correspond to waveform characteristics obtained during a first period, and the one or more waveform characteristics are received during a second period, wherein the first period occurs prior to the second period.
4 . The method of claim 1 further comprising determining the one or more target characteristics based on a plurality of waveform characteristics obtained over a period of time.
5 . The method of claim 1 wherein determining the one or more control parameters based on the one or more waveform characteristics and the one or more target characteristics comprises comparing the one or more waveform characteristics with the one or more target characteristics.
6 . The method of claim 1 , wherein the pulsed voltage waveform is coupled to a biasing electrode disposed within the substrate processing chamber.
7 . The method of claim 1 , wherein the one or more waveform characteristics are determined from a digitized voltage waveform, wherein the digitized voltage waveform is determined from a conditioned voltage determined from the input voltage waveform.
8 . The method of claim 1 further comprising adjusting, via the pulsed voltage waveform, one or more characteristics of the pulsed voltage waveform.
9 . A controller for a substrate processing chamber, the controller configured to:
receive, from a first input channel of a data acquisition system connected to the substrate processing chamber, one or more waveform characteristics of a input voltage waveform;
determine one or more control parameters based on the one or more waveform characteristics and one or more target characteristics; and
output the one or more control parameters to a pulsed voltage waveform generator electrically coupled to the substrate processing chamber, wherein the one or more control parameters provide an indication to adjust a pulsed voltage waveform established by the pulsed voltage waveform generator.
10 . The controller of claim 9 is further configured to receive the one or more target characteristics from a memory.
11 . The controller of claim 9 , wherein the one or more target characteristics correspond to waveform characteristics obtained during a first period, and the one or more waveform characteristics are received during a second period, wherein the first period occurs prior to the second period.
12 . The controller of claim 9 , wherein the one or more target characteristics are determined based on a plurality of waveform characteristics obtained over a period of time.
13 . The controller of claim 9 , wherein determining the one or more control parameters based on the one or more waveform characteristics and the one or more target characteristics comprises comparing the one or more waveform characteristics with the one or more target characteristics.
14 . The controller of claim 9 , wherein the one or more waveform characteristics are determined from a digitized voltage waveform, wherein the digitized voltage waveform is determined from a conditioned voltage determined from the input voltage waveform.
15 . A substrate processing system comprising:
a substrate processing chamber;
a data acquisition system connected to the substrate processing chamber, wherein the data acquisition system comprises an input channel;
a pulsed voltage waveform generator electrically coupled to the substrate processing chamber; and
a controller comprising a non-volatile memory that includes instructions that, when executed by a processor of the controller, is configured to perform a method comprising:
receiving, via the input channel, a one or more waveform characteristics of a input voltage waveform generated by the pulsed voltage waveform generator;
determining, via the controller, one or more control parameters based on the one or more waveform characteristics and one or more target characteristics stored in the non-volatile memory; and
transmitting, via the controller, information relating to the one or more control parameters to the pulsed voltage waveform generator, wherein the pulsed voltage waveform generator adjusts a pulsed voltage waveform generated by the pulsed voltage waveform generator based on the transmitted information relating to the one or more control parameters.
16 . The substrate processing system of claim 15 , wherein the one or more target characteristics are received by the controller from a memory.
17 . The substrate processing system of claim 15 , wherein the one or more target characteristics correspond to waveform characteristics obtained during a first period and the one or more waveform characteristics are received during a second period, wherein the first period occurs prior to the second period.
18 . The substrate processing system of claim 15 , wherein the one or more target characteristics are determined based on a plurality of waveform characteristics obtained over a period of time.
19 . The substrate processing system of claim 15 , wherein determining the one or more control parameters based on the one or more waveform characteristics and the one or more target characteristics comprises comparing the one or more waveform characteristics with the one or more target characteristics.
20 . The substrate processing system of claim 15 , wherein the input channel is configured to generate a conditioned voltage waveform from the input voltage waveform, and wherein the data acquisition system further comprises:
an acquisition channel coupled to the input channel, the acquisition channel is configured to generate a digitized voltage waveform from the conditioned voltage waveform; and
a data acquisition controller configured to determine the one or more waveform characteristics based on the digitized voltage waveform.