Taper etching without re-entrance profile

A method of forming tapered contact via holes, comprising the steps of:

• providing an integrated circuit structure having device elements within a semiconductor substrate, contact areas in said semiconductor substrate, and a layer of borophosphosilicate glass having a thickness of between about 5000 and 9000 Angstroms over said semiconductor substrate;
• forming a photoresist masking layer over said layer of borophosphosilicate glass;
• forming openings in said photoresist masking layer directly over said contact areas;
• wet etching into said layer of borophosphosilicate glass through a first thickness, thereby forming a first via hole opening, using said photoresist masking layer as a mask;
• isotropically etching, by means of a dry isotropic etch, into said layer of borophosphosilicate glass through a second thickness, thereby forming a second via hole opening, using said photoresist masking layer as a mask;
• vertically anisotropically etching, by means of a dry anisotropic etch, through the remainder of said layer of borophosphosilicate glass, thereby forming said tapered contact via hole opening, using said photoresist masking layer as a mask;
• and
• removing said photoresist masking layer.

A method of forming tapered contact via holes, comprising the steps of:

• providing an integrated circuit structure having device elements within a semiconductor substrate, contact areas in said semiconductor substrate, and a layer of silicon dioxide having a thickness of between about 7500 and 9000 Angstroms over said semiconductor substrate;
• forming a photoresist masking layer over said layer of silicon dioxide;
• forming openings in said photoresist masking layer directly over said contact areas;
• wet etching into said layer of silicon dioxide through a first thickness, thereby forming a first via hole opening, using said photoresist masking layer as a mask;
• isotropically etching, by means of a dry isotropic etch, into said layer of silicon dioxide through a second thickness, thereby forming a second via hole opening, using said photoresist masking layer as a mask;
• vertically anisotropically etching, by means of a dry anisotropic etch, through the remainder of said layer of silicon dioxide, thereby forming said tapered contact via hole opening, using said photoresist masking layer as a mask;
• and
• removing said photoresist masking layer.

A method of forming tapered contact via holes, comprising the steps of:

• providing an integrated circuit structure having device elements within a semiconductor substrate, contact areas in said semiconductor substrate, and a layer of glass having a thickness of between about 7500 and 9000 Angstroms over said semiconductor substrate;
• forming a photoresist masking layer over said layer of glass;
• forming openings in said photoresist masking layer directly over said contact areas;
• wet etching into said layer of glass through a first thickness, thereby forming a first via hole opening, using said photoresist masking layer as a mask;
• isotropically etching, by means of a dry isotropic etch, into said layer of glass through a second thickness, thereby forming a second via hole opening, using said photoresist masking layer as a mask;
• vertically anisotropically etching, by means of a dry anisotropic etch, through the remainder of said layer of glass, thereby forming said tapered contact via hole opening, using said photoresist masking layer as a mask;
• and
• removing said photoresist masking layer.