Selective wet etching of hafnium aluminum oxide films

A method of forming a semiconductor device, comprising:

• etching a hafnium aluminum oxide layer and a DARC layer through a patterned photoresist mask to expose a silicon oxide layer, the DARC layer overlying and in contact with the hafnium aluminum oxide layer;
• etching the silicon oxide layer to form an opening extending to a substrate;
• removing the patterned photoresist mask to expose the DARC layer;
• and
• applying an etchant solution consisting essentially of phosphoric acid and water to selectively etch the hafnium aluminum oxide and DARC layers at a rate greater than the silicon oxide.

A method of forming a semiconductor device, comprising:

• forming a hafnium aluminum oxide layer over a silicon oxide layer situated on a substrate;
• forming a DARC layer over the hafnium aluminum oxide layer;
• forming a patterned photoresist layer over the DARC layer to expose the DARC layer;
• etching the hafnium aluminum oxide and DARC layers through the patterned photoresist layer to expose the silicon oxide layer;
• etching the silicon oxide layer to form an opening extending to the substrate;
• removing the patterned photoresist layer to expose the DARC layer;
• and
• applying an etchant solution consisting essentially of phosphoric acid and water to selectively remove the hafnium aluminum oxide and DARC layers at a rate greater than the silicon oxide.

A method of forming a semiconductor device, comprising:

• etching hafnium aluminum oxide and DARC layers through a patterned photoresist layer to expose a silicon oxide layer, the DARC layer overlying and in contact with the hafnium aluminum oxide layer;
• etching the silicon oxide layer to form an opening extending to an underlying substrate;
• removing the patterned photoresist layer to expose the DARC layer;
• and
• applying an etchant solution consisting essentially of phosphoric acid and water to selectively remove the hafnium aluminum oxide and DARC layers at a rate greater than the silicon oxide.

A method of forming a semiconductor device, comprising:

• etching a hafnium aluminum oxide layer and DARC layer through a patterned photoresist mask to expose a silicon oxide layer, the DARC layer overlying and in contact with the hafnium aluminum oxide layer;
• etching the silicon oxide layer to form an opening extending to a substrate;
• removing the patterned photoresist mask to expose the DARC layer;
• and
• applying an etchant solution consisting essentially of phosphoric acid, water and a pH modifying acid to selectively etch the hafnium aluminum oxide and DARC layers at a rate greater than the silicon oxide.