Self-aligned contact process implementing bias compensation etch endpoint detection and methods for implementing the same

Abstract

A bias compensation self-aligned contact (SAC) etch endpoint detecting system is provided. The system includes an etch reactant chamber, an ESC power supply, and a signal processing computer. The etch reactant chamber includes an electrostatic chuck (ESC), a top electrode, and a bottom electrode. The ESC supports a substrate having an interlevel dielectric (ILD) layer to be etched. The ESC power supply is coupled to the ESC and is configured to function as a bias compensating power supply. The signal processing computer monitors a bias compensation signal generated by the ESC power supply. The etch process to be carried out in the etch reactant chamber is configured to be discontinued when the bias compensation signal is determined to have a previously ascertained characteristic evidencing an etch endpoint of the ILD layer.

1 . A bias compensation self-aligned contact (SAC) etch endpoint detecting system, the system comprising: 
 an etch reactant chamber configured to include an electrostatic chuck (ESC), a top electrode, and a bottom electrode, the ESC configured to support a substrate having an interlevel dielectric (ILD) layer to be etched;    an ESC power supply coupled to the ESC, the ESC power supply being configured to function as a bias compensating power supply; and    a signal processing computer configured to monitor a bias compensation signal generated by the ESC power supply,    wherein an etch process to be carried out in the etch reactant chamber is configured to be discontinued when the bias compensation signal is determined to have a previously ascertained characteristic evidencing an etch endpoint of the ILD layer.    
   
   
       2 . An SAC etch endpoint detecting system as recited in  claim 1 , wherein the previously ascertained characteristic evidencing the etch endpoint of the ILD layer is a change in a bias compensation voltage.  
   
   
       3 . An SAC etch endpoint detecting system as recited in  claim 2 , wherein the bias compensation voltage configured to evidence the etch endpoint of the ILD layer correlates with a substantial removal of exposed portions of the ILD layer and a substantial exposure of a portion of an underlying layer defined below the exposed portion of the ILD layer.  
   
   
       4 . An SAC etch endpoint detecting system as recited in  claim 2 , wherein the previously ascertained characteristic evidencing the etch endpoint of the ILD layer is an expected step increase in the bias compensation voltage.  
   
   
       5 . An SAC etch endpoint detecting system as recited in  claim 3 , wherein the underlying layer is a source/drain diffusion region.  
   
   
       6 . A bias compensation etch system, the system comprising: 
 an etch reactant chamber configured to include an electrostatic chuck (ESC) being configured to support a substrate to be processed, the substrate having an interlevel dielectric (ILD) layer to be etched;    a radio frequency (RF) power supply component coupled to the ESC, the RF power supply component configured to excite a plasma defined within the etch reactant chamber; and    an etch endpoint monitoring circuitry coupled to the ESC, wherein the etch endpoint monitoring circuitry is configured to provide bias compensating power to the ESC and monitor a generated bias compensation signal, and further wherein the etch endpoint monitoring circuitry is configured to discontinue an etch process being carried out in the etch reactant chamber when a previously ascertained characteristic of the bias compensation signal evidencing an etch endpoint of the ILD layer has been detected.    
   
   
       7 . A system as recited in  6 , wherein the etch reactant chamber further includes, 
 a shower head defined at a top wall of the etch reactant chamber wherein an etchant gas is introduced into the etch reactant chamber by passing through the showerhead.    
   
   
       8 . A system as recited in  claim 7 , further comprising: 
 a second RF supply component being coupled to the showerhead so as to excite the plasma defined within the etch reactant chamber.    
   
   
       9 . A system as recited in  claim 6 , wherein the generated bias compensation signal reflects a change in a resistance of the substrate.  
   
   
       10 . A system as recited in  claim 6 , wherein the etch reactant chamber further includes a containment ring configured to substantially confine the plasma within a plasma region.  
   
   
       11 . A system as recited in  claim 6 , the system further including an exhaust pipe secured to the etch reactant chamber so as to release a content of the etch reactant chamber.  
   
   
       12 . A system as recited in  claim 6 , wherein the ESC includes a pair of electrodes coupled to terminals of the etch endpoint monitoring circuitry.  
   
   
       13 . A system as recited in  claim 12 , the system further including a supply tube configured to supply a cooling gas to a portion of the ESC.  
   
   
       14 . The system as recited in  claim 6 , wherein the previously ascertained characteristic of the bias compensation signal evidencing the etch endpoint of the ILD layer is a change in a bias compensation voltage.  
   
   
       15 . The system as recited in  claim 14 , wherein the bias compensation voltage configured to evidence the etch endpoint of the ILD layer correlates with a substantial removal of exposed portions of the ILD layer and a substantial exposure of a portion of an underlying layer defined below the exposed portion of the ILD layer.  
   
   
       16 . The system as recited in  claim 14 , wherein the previously ascertained characteristic evidencing the etch endpoint of the ILD layer is an expected step increase in the bias compensation voltage.  
   
   
       17 . The system as recited in  claim 15 , wherein the underlying layer is a source/drain diffusion region.