Negative ion control for dielectric etch
First Claim
1. A method for operating a capacitively-coupled plasma in a chamber having a bottom electrode and a top electrode, the method comprising:
- applying a bottom radio frequency (RF) signal set at a first phase to the bottom electrode in the chamber;
calculating, for an etch process and a distance between the top electrode and bottom electrode, a travel time for negative ions formed in the chamber to reach the bottom electrode; and
applying a top RF signal to the top electrode in the chamber, wherein the first phase and a second phase are adjusted to maintain a time difference between a maximum of the top RF signal and a minimum of the bottom RF signal, the time difference is set based on the calculated travel time for the negative ions,wherein the first phase and the second phase are adjusted so that the minimum of the bottom RF signal is offset from the first phase producing the maximum of the top RF signal based on the calculated travel time between the top electrode and bottom electrode.
0 Assignments
0 Petitions
Accused Products
Abstract
Apparatus, methods, and computer programs for semiconductor processing in a capacitively-coupled plasma chamber are provided. A chamber includes a bottom radio frequency (RF) signal generator, a top RF signal generator, and an RF phase controller. The bottom RF signal generator is coupled to the bottom electrode in the chamber, and the top RF signal generator is coupled to the top electrode. Further, the bottom RF signal is set at a first phase, and the top RF signal is set at a second phase. The RF phase controller is operable to receive the bottom RF signal and operable to set the value of the second phase. Additionally, the RF phase controller is operable to track the first phase and the second phase to maintain a time difference between the maximum of the top RF signal and the minimum of the bottom RF signal at approximately a predetermined constant value, resulting in an increase of the negative ion flux to the surface of the wafer.
41 Citations
16 Claims
-
1. A method for operating a capacitively-coupled plasma in a chamber having a bottom electrode and a top electrode, the method comprising:
-
applying a bottom radio frequency (RF) signal set at a first phase to the bottom electrode in the chamber; calculating, for an etch process and a distance between the top electrode and bottom electrode, a travel time for negative ions formed in the chamber to reach the bottom electrode; and applying a top RF signal to the top electrode in the chamber, wherein the first phase and a second phase are adjusted to maintain a time difference between a maximum of the top RF signal and a minimum of the bottom RF signal, the time difference is set based on the calculated travel time for the negative ions, wherein the first phase and the second phase are adjusted so that the minimum of the bottom RF signal is offset from the first phase producing the maximum of the top RF signal based on the calculated travel time between the top electrode and bottom electrode. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
-
-
9. A method for operating a chamber that generates a capacitively-coupled plasma, the method comprising:
-
applying a bottom radio frequency (RF) signal to a bottom electrode in the chamber, the bottom RF signal set at a first frequency at a first phase; applying a top RF signal at the first frequency to a top electrode in the chamber, the top electrode set at a distance from the bottom electrode; calculating a travel time required for negative ions formed near a top plasma sheath in the chamber to travel the distance towards the bottom electrode; determining a second phase for the top RF signal based on the travel time based on a time offset between a maximum of the top RF signal and a minimum of the bottom RF signal for the travel time; and using the second phase for the top RF signal while using the first phase for the bottom RF signal. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
-
Specification