Methods of selectively etching polysilicon relative to at least one of deposited oxide, thermally grown oxide and nitride, and methods of selectively etching polysilicon relative to BPSG

A method of selectively etching polysilicon relative to BPSG comprising:

• forming a substrate to have a layer comprising polysilicon received over a BPSG comprising layer;
• and
• exposing the polysilicon to an aqueous solution comprising NH4F, an oxidizer, CH3COOH, TMAH, and HF within volumetric ranges of about 90-135:
• 70-280:
• 1.5-5.0:
• 0.07-0.30:
• 0.19-0.30, respectively, under conditions effective to selectively etch at least a portion of the polysilicon comprising layer relative to an ultimately exposed portion of the BPSG comprising layer, the conditions comprising a temperature of from about 12° C. to about 32° C.

A method of selectively etching polysilicon relative to BPSG comprising:

• forming a substrate to have a layer comprising polysilicon received over a BPSG comprising layer;
• and
• exposing the polysilicon to an aqueous solution comprising NH4F, an oxidizer, CH3COOH, TMAF within volumetric ranges of about 90-135:
• 70-280:
• 1.5-5.0:
• 0.17-0.53, respectively, under conditions effective to selectively etch at least a portion of the polysilicon comprising layer relative to an ultimately exposed portion of the BPSG comprising layer, the conditions comprising a temperature of from about 12° C. to about 32° C.

A method of selectively etching polysilicon relative to BPSG, comprising:

• forming a substrate to have a layer comprising polysilicon received over a BPSG comprising layer;
• and
• exposing the polysilicon to an aqueous solution comprising NH4F, H2O2, CH3COOH, TMAH, and HF within volumetric ranges of about 112-124:
• 105-245:
• 2.0-4.5:
• 0.120-0.228:
• 0.22-0.28 respectively, under conditions effective to selectively etch at least a portion of the polysilicon comprising layer relative to an ultimately exposed portion of the BPSG comprising layer, the conditions comprising a temperature of from about 20° C. to about 24° C.

A method of selectively etching polysilicon relative to BPSG comprising:

• forming a substrate to have a layer comprising polysilicon received over a BPSG comprising layer;
• and
• exposing the polysilicon to an aqueous solution comprising NH4F, an oxidizer, CH3COOH, TMAF within volumetric ranges of about 90-135:
• 70-280:
• 1.5-5.0:
• 0.26-0.44, respectively, under conditions effective to selectively etch at least a portion of the polysilicon comprising layer relative to an ultimately exposed portion of the BPSG comprising layer, the conditions comprising a temperature of from about 20° C. to about 24° C.

A method of selectively etching polysilicon relative to BPSG, comprising:

• forming a substrate to have a layer comprising undoped polysilicon received over a BPSG comprising layer;
• and
• exposing the polysilicon to an aqueous solution comprising NH4F, H2O2, CH3COOH, TMAH, and HF within volumetric ranges of about 112-124:
• 105-245:
• 2.0-4.5:
• 0.120-0.228:
• 0.22-0.28 respectively, under conditions effective to selectively etch at least a portion of the undoped polysilicon comprising layer relative to an ultimately exposed portion of the BPSG comprising layer, the conditions comprising a temperature of from about 20° C. to about 24° C., and achieving selectivity of at least 2.5:1.

A method of selectively etching polysilicon relative to BPSG, comprising:

• forming a substrate to have a layer comprising undoped polysilicon received over a BPSG comprising layer;
• and
• exposing the polysilicon to an aqueous solution comprising NH4F, an oxidizer, CH3COOH, TMAF within volumetric ranges of about 90-135:
• 70-280:
• 1.5-5.0:
• 0.26-0.44, respectively, under conditions effective to selectively etch at least a portion of the polysilicon comprising layer relative to an ultimately exposed portion of the BPSG comprising layer, the conditions comprising a temperature of from about 20° C. to about 24° C., and achieving selectivity of at least 2.5:1.