Mechanism for etching a silicon layer in a plasma processing chamber to form deep openings

Abstract

A method of etching a silicon layer in a plasma etching reactor to form an ultra deep opening is disclosed. The method includes the steps of providing a semiconductor substrate including the silicon layer into the plasma etching reactor and flowing an etching gas that includes an oxygen reactant gas, a helium gas, and an inert bombardment-enhancing gas into the plasma etching reactor. The method further includes striking a plasma using the etchant gas chemistry, and then providing an additive gas having SF 6 into the plasma etching reactor subsequent to striking the plasma. The method continues with etching an opening at least partially through the silicon layer using this plasma.

What is claimed is:  
     
         1 . A method of etching a silicon layer in an inductively coupled plasma etching reactor to form an ultra deep trench, said ultra deep trench having an etch depth of at least 10 μm , said method comprising: 
 providing a semiconductor substrate into said inductively coupled plasma etching reactor, said semiconductor substrate including said silicon layer;  
 flowing an etchant gas chemistry consisting essentially of a helium gas, an O 2  gas, and an argon gas into said inductively coupled plasma etching reactor;  
 striking a plasma using said etchant gas chemistry;  
 providing an SF 6  gas into said inductively coupled plasma etching reactor subsequent to said striking said plasma, wherein a flow ratio of said helium gas to said SF 6  gas is about 350% to about 550%, a flow ratio of O 2  to said SF 6  gas is about 60% to about 90%, and a flow ratio of said argon gas to said SF 6  gas is about 350% to about 550%; and  
 etching said ultra deep trench at least partially through said silicon layer.  
 
     
     
         2 . The method of etching a silicon layer in an inductively coupled plasma etching reactor to form an ultra deep opening as in    claim 1   , wherein a native oxide layer is disposed over said silicon layer and a chlorine-containing gas chemistry is flowed into said inductively coupled plasma etching reactor, said chlorine-containing gas chemistry being used to etch through said native oxide layer prior to said flowing of said etchant gas chemistry for said etching said silicon layer.  
     
     
         3 . The method of etching a silicon layer in an inductively coupled plasma etching reactor to form an ultra deep opening as in    claim 1   , wherein a flow ratio of said argon gas to said SF 6  gas is about 350% to about 550%.  
     
     
         4 . The method of etching a silicon layer in an inductively coupled plasma etching reactor to form an ultra deep opening as in    claim 1   , wherein said etching of said ultra deep opening continues down to an etch depth of between about 30 μm and about 60 μm.  
     
     
         5 . The method of etching a silicon layer in an inductively coupled plasma etching reactor to form an ultra deep opening as in    claim 1   , wherein said striking of said plasma is sustained for a time period between about 5 seconds and about 10 seconds.  
     
     
         6 . A method of etching a silicon layer in a plasma etching reactor to form an ultra deep opening, said method comprising: 
 providing a semiconductor substrate into said plasma etching reactor, said semiconductor substrate including said silicon layer;    flowing an etchant gas chemistry having a helium gas, an oxygen reactant gas, and an inert bombardment-enhancing gas into said plasma etching reactor;    striking a plasma using said etchant gas chemistry;    providing a fluorine-containing additive gas into said plasma etching reactor subsequent to said striking said plasma; and    etching said ultra deep opening at least partially through said silicon layer.    
     
     
         7 . The method of etching a silicon layer in a plasma etching reactor to form an ultra deep opening as in    claim 6   , wherein a native oxide layer is disposed over said silicon layer and a chlorine-containing gas chemistry is flowed into said plasma etching reactor, said chlorine-containing gas chemistry being used to etch through said native oxide layer prior to said flowing of said etchant gas chemistry for said etching said silicon layer.  
     
     
         8 . The method of etching a silicon layer in a plasma etching reactor to form an ultra deep opening as in    claim 6   , wherein said inert bombardment-enhancing gas is argon.  
     
     
         9 . The method of etching a silicon layer in a plasma etching reactor to form an ultra deep opening as in    claim 6   , wherein said inert bombardment-enhancing gas is xenon.  
     
     
         10 . The method of etching a silicon layer in a plasma etching reactor to form an ultra deep opening as in    claim 6   , wherein said semiconductor substrate is a silicon wafer.  
     
     
         11 . The method of etching a silicon layer in a plasma etching reactor to form an ultra deep opening as in    claim 6   , wherein said ultra deep opening is a trench.  
     
     
         12 . The method of etching a silicon layer in a plasma etching reactor to form an ultra deep opening as in    claim 6   , wherein a flow ratio of said inert bombardment-enhancing gas to said SF 6  gas is about 350% to about 550%.  
     
     
         13 . The method of etching a silicon layer in a plasma etching reactor to form an ultra deep opening as in    claim 6   , wherein said fluorine-containing additive gas is SF 6 .  
     
     
         14 . The method of etching a silicon layer in a plasma etching reactor to form an ultra deep opening as in    claim 6   , wherein said fluorine-containing additive gas is one of C 4 F 8 , CF 4 , NF 3 , and CHF 3 .  
     
     
         15 . The method of etching a silicon layer in a plasma etching reactor to form an ultra deep opening as in    claim 6   , wherein said etching of said ultra deep opening continues down to an etch depth of between about 30 μm and about 60 μm.  
     
     
         16 . The method of etching a silicon layer in a plasma etching reactor to form an ultra deep opening as in    claim 6   , wherein a lower electrode temperature in said plasma etching reactor is between about 15° C. and about 60° C.  
     
     
         17 . The method of etching a silicon layer in a plasma etching reactor to form an ultra deep opening as in    claim 6   , wherein a chamber pressure in said plasma etching reactor is between about 50 mTorr and about 60 mTorr.  
     
     
         18 . The method of etching a silicon layer in a plasma etching reactor to form an ultra deep opening as in    claim 6   , wherein said striking of said plasma is sustained for a time period between about 5 seconds and about 10 seconds.  
     
     
         19 . The method of etching a silicon layer in a plasma etching reactor to form an ultra deep opening as in    claim 6   , wherein a top power in said plasma etching reactor is between about 400 W and about 1000 W.  
     
     
         20 . The method of etching a silicon layer in a plasma etching reactor to form an ultra deep opening as in    claim 6   , wherein said plasma etching reactor is an inductively coupled plasma etching reactor.  
     
     
         21 . A method of etching a silicon layer in a plasma etching reactor to form a deep opening, said method comprising: 
 providing a semiconductor substrate into said plasma etching reactor, said semiconductor substrate including said silicon layer;    flowing an etchant gas chemistry having a helium gas, and an oxygen reactant gas into said plasma etching reactor;    striking a plasma using said etchant gas chemistry;    providing a fluorine-containing additive gas into said plasma etching reactor subsequent to said striking said plasma; and    etching said deep opening at least partially through said silicon layer, said etching of said silicon layer being performed using said plasma.    
     
     
         22 . The method of etching a silicon layer in a plasma etching reactor to form a deep opening as in    claim 21   , wherein a native oxide layer is disposed over said silicon layer and a chlorine-containing gas chemistry is flowed into said plasma etching reactor, said chlorine-containing gas chemistry being used to etch through said native oxide layer prior to said flowing of said etchant gas chemistry for said etching said silicon layer.  
     
     
         23 . The method of etching a silicon layer in a plasma etching reactor to form a deep opening as in    claim 21   , wherein said semiconductor substrate is a silicon wafer.  
     
     
         24 . The method of etching a silicon layer in a plasma etching reactor to form a deep opening as in    claim 21   , wherein said deep opening is a trench.  
     
     
         25 . The method of etching a silicon layer in a plasma etching reactor to form a deep opening as in    claim 21   , wherein said fluorine-containing additive gas is SF 6 .  
     
     
         26 . The method of etching a silicon layer in a plasma etching reactor to form a deep opening as in    claim 21   , wherein said fluorine-containing additive gas is one of C 4 F 8 , CF 4 , NF 3 , and CHF 3 .  
     
     
         28 . The method of etching a silicon layer in a plasma etching reactor to form a deep opening as in    claim 21   , wherein said etching of said deep opening continues down to an etch depth of between about 10 μm and about 15 μm.  
     
     
         29 . The method of etching a silicon layer in a plasma etching reactor to form an ultra deep opening as in    claim 21   , wherein a flow ratio of said helium gas to said SF 6  gas is about 350% to about 550%.  
     
     
         30 . The method of etching a silicon layer in a plasma etching reactor to form a deep opening as in    claim 21   , wherein a chamber pressure in said plasma etching reactor is between about 40 mTorr and about 100 mTorr.  
     
     
         31 . The method of etching a silicon layer in a plasma etching reactor to form a deep opening as in    claim 21   , wherein said striking of said plasma is sustained for a time period between about 5 seconds and about 10 seconds.  
     
     
         32 . The method of etching a silicon layer in a plasma etching reactor to form a deep opening as in    claim 21   , wherein a top power in said plasma etching reactor is between about 300 W and about 2000 W.