Method for removing post-etch residue from wafer surface

Abstract

A low-k dielectric film is deposited on the wafer. A metal layer is then deposited over the low-k dielectric film. A resist pattern is formed over the metal layer. The resist pattern is then transferred to the underlying metal layer to form a metal pattern. The resist pattern is stripped off. A through hole is plasma etched into the low-k dielectric film by using the metal pattern as a hard mask. The plasma etching causes residues to deposit within the through hole. A wet treatment is then performed to soften the residues. A plasma dry treatment is carried out to crack the residues.

1 . A method for removing post-etch residues from surfaces of a wafer, comprising: 
 depositing at least one low-k (k<3) dielectric film on said wafer;    depositing a metal layer over said low-k dielectric film;    forming a resist pattern over said metal layer;    transferring said resist pattern to said metal layer to form a metal pattern;    stripping said resist pattern;    plasma etching a through hole into said low-k dielectric film by using said metal pattern as a hard mask, wherein said plasma etching causes residues to deposit within said through hole;    performing a wet treatment to soften said residues; and    after performing said wet treatment, performing a plasma dry treatment to crack said residues, the plasma dry treatment comprising:    exposing said wafer and said softened residues to an oxidizing plasma atmosphere with the presence of oxygen and hydrogen; followed by exposing said wafer and said residues to a reducing plasma atmosphere with the absence of oxygen.    
   
   
       2 . The method according to  claim 1  wherein said wet treatment uses fluoride-based solvent.  
   
   
       3 . The method according to  claim 1  wherein said metal layer comprises titanium, titanium nitride, tantalum, tantalum nitride, or any combination thereof.  
   
   
       4 . The method according to  claim 1  wherein before depositing said metal layer, a chemical mechanical polish (CMP) stop layer is deposited onto said low-k dielectric film.  
   
   
       5 . The method according to  claim 1  wherein before forming said resist pattern, a dielectric hard mask is deposited over said metal layer.  
   
   
       6 . A method for removing post-etch residues from surfaces of a wafer, wherein said post-etch residues are formed partly due to the use of a metal hard mask during etching, said method comprising: 
 performing a wet treatment to soften said residues;    after performing said wet treatment, performing a plasma dry treatment to crack said residues, wherein said plasma dry treatment further comprises two stages:    (1) exposing said wafer and said softened residues to an oxidizing plasma atmosphere at a first temperature with the presence of oxygen and hydrogen; and    (2) exposing said wafer and said residues to a reducing plasma atmosphere at a second temperature with the absence of oxygen.    
   
   
       7 . The method according to  claim 6  wherein said wet treatment uses fluoride-based solvent.  
   
   
       8 . The method according to  claim 6  wherein said oxidizing plasma atmosphere further includes a carrier gas.  
   
   
       9 . The method according to  claim 6  wherein said reducing plasma atmosphere is He/H 2  plasma.  
   
   
       10 . The method according to  claim 6  wherein said first temperature is higher than room temperature.  
   
   
       11 . The method according to  claim 6  wherein said second temperature is higher than 200° C.  
   
   
       12 . A method for removing post-etch residues of etching damascene opening from surfaces of a wafer, wherein said post-etch residues is formed partly due to the use of a metal hard mask during etching, the damascene opening exposing a metal oxide, said method comprising: 
 performing a wet treatment to soften said residues;    performing a plasma dry treatment to crack said residues, wherein said plasma dry treatment comprises two stages:    (1) exposing said wafer and said softened residues to an oxidizing plasma atmosphere at a first temperature with the presence of oxygen and hydrogen; and    (2) exposing said wafer and said residues to a reducing plasma atmosphere at a second temperature with the absence of oxygen, for the metal oxide being reduced.    
   
   
       13 . The method according to  claim 12  wherein said wet treatment uses fluoride-based solvent.  
   
   
       14 . The method according to  claim 12  wherein said oxidizing plasma atmosphere further includes a carrier gas.  
   
   
       15 . The method according to  claim 12  wherein said reducing plasma atmosphere is He/H 2  plasma.  
   
   
       16 . The method according to  claim 12  wherein said first temperature is higher than room temperature.  
   
   
       17 . The method according to  claim 12  wherein said second temperature is higher than 200° C.