Pulsed plasma chamber in dual chamber configuration

Abstract

Embodiments for processing a substrate in a pulsed plasma chamber are provided. A processing apparatus with two chambers, separated by a plate fluidly connecting the chambers, includes a continuous wave (CW) controller, a pulse controller, and a system controller. The CW controller sets the voltage and the frequency for a first radio frequency (RF) power source coupled to a top electrode. The pulse controller is operable to set voltage, frequency, ON-period duration, and OFF-period duration for a pulsed RF signal generated by a second RF power source coupled to the bottom electrode. The system controller is operable to regulate the flow of species between the chambers to assist in the negative-ion etching, to neutralize excessive positive charge on the wafer surface during afterglow in the OFF-period, and to assist in the re-striking of the bottom plasma during the ON -period.

1 . A wafer processing apparatus, comprising:
 an upper chamber including a gas intake configured to provide a first flow of gas received from a first gas source to the upper chamber, the upper chamber configured to generate an upper plasma;   an upper electrode connected to a radio frequency (RF) power source, wherein the RF power source provides continuous RF power to the upper electrode, wherein the upper electrode is always powered ON during operation;   a lower chamber configured to generate a lower plasma through capacitive coupling;   a perforated grounded electrode separating the upper chamber from the lower chamber, the perforated grounded electrode having a plurality of through holes to enable a flow of neutral and charged species from the upper plasma in the upper chamber to the lower chamber, wherein the perforated grounded electrode includes a plurality of gas outlets providing a second flow of gas from a second gas source to the lower chamber; and   a lower electrode in the lower chamber connected to a first pulsed RF power source providing a first pulsed RF power to the lower electrode.   
     
     
         2 . The wafer processing apparatus of  claim 1 , further comprising:
 a pulse controller operate to set a voltage and a frequency of the pulsed RF power source, and to set a pulsing cycle for the pulsed RF power source.   
     
     
         3 . The wafer processing apparatus of  claim 1 , further comprising:
 a continuous wave (CW) controller to set a voltage and frequency of a continuous wave RF signal for the continuous RF power source.   
     
     
         4 . The wafer processing apparatus of  claim 1 ,
 wherein the upper chamber and upper electrode are configured as an inductively coupled plasma chamber to form the upper plasma through inductive coupling.   
     
     
         5 . The wafer processing apparatus of  claim 1 ,
 wherein the upper chamber and upper electrode are configured as another CCP chamber to form the upper plasma through capacitive coupling.   
     
     
         6 . The wafer processing apparatus of  claim 1 , further comprising:
 a second pulsed RF power source providing a second pulsed RF power to the lower electrode.   
     
     
         7 . The wafer processing apparatus of  claim 1 , further comprising:
 a system controller configured to set parameters for the upper chamber and parameter for the lower chamber to regulate the flow of neutral and charged species from the upper chamber to the lower chamber through the perforated grounded electrode during an ON-period duration and an OFF-period duration for a pulsing cycle for the pulsed RF power source.   
     
     
         8 . The wafer processing apparatus of  claim 7 ,
 wherein the system controller is operable to set a first pressure in the upper chamber and a second pressure in the lower chamber,   wherein the first pressure is higher than the second pressure.   
     
     
         9 . The wafer processing apparatus of  claim 7 ,
 wherein the system controller regulates the flow of neutral and charged species from the upper chamber to the bottom chamber to control negative-ion etching in the lower chamber and to regulate positive charge on the wafer surface during an afterglow phase of the OFF-period.   
     
     
         10 . The wafer processing apparatus as recited in  claim 1 ,
 wherein the system controller is configured to regulate the flow of neutral and charged species to enable control of etching of the wafer during the ON-period and during the OFF-period.   
     
     
         11 . The wafer processing apparatus as recited in  claim 1 ,
 wherein the system controller maintains in the upper chamber a continuous top plasma that is not pulsed, wherein the continuous upper plasma on the upper chamber increases an amount of negative ions in the lower chamber during the OFF-period to improve etching with negative ions in the lower chamber, wherein electrons from the upper chamber travel to the lower chamber and attach to ions in the lower chamber to create more negative ions in the lower chamber during the OFF-period.   
     
     
         12 . The wafer processing apparatus as recited in  claim 1 ,
 wherein the parameters for the lower chamber includes a lower chamber pressure,   wherein the system controller regulates the flow of electrons from the upper chamber to the lower chamber to assist in re-striking the lower plasma during the ON-period.   
     
     
         13 . The wafer processing apparatus as recited in  claim 1 ,
 wherein an interior cavity surround the upper chamber and the lower chamber.