Addition of ballast hydrocarbon gas to doped polysilicon etch masked by resist

A method for etching a gate on a semiconductor wafer comprising:

• providing a semiconductor wafer within a processing chamber, said semiconductor wafer having a patterned photo resist layer with varying concentrations of hydrocarbons over a gate layer;
• flowing an etchant into said processing chamber;
• contacting said etchant to said semiconductor wafer to generate a hydrocarbon-containing reaction by-product that is diffused throughout said etchant at varying concentrations across said semiconductor wafer;
• determining a percentage of soft mask photo resist pattern differences across the semiconductor wafer;
• calculating an amount of a hydrocarbon gas that compensates for said pattern differences using said percentage;
• adding said amount of hydrocarbon gas within said processing chamber to equilibrate said varying concentrations of said hydrocarbon-containing reaction by-product and provide a homogeneous etchant across the entire said semiconductor wafer;
• and
• etching a gate into said gate layer using said patterned photo resist layer by contacting said gate layer with said homogeneous etchant, while simultaneously depositing a passivation layer over all exposed surfaces during said etching to provide uniform etching results.

A method for etching a gate on a semiconductor wafer comprising:

• providing a semiconductor wafer having a photo resist layer with varying patterns with varying concentrations of hydrocarbons over a gate layer;
• providing said semiconductor wafer within a processing chamber;
• flowing an etchant into said processing chamber;
• contacting said etchant to said semiconductor wafer to generate varying concentrations of a hydrocarbon-containing reaction by-product across said varying patterns of said photo resist layer;
• adding a gas within said processing chamber to compensate for said varying concentrations of said hydrocarbon-containing reaction by-product across said varying patterns by forming a homogeneous etchant having a uniform concentration of hydrocarbons across the entire said semiconductor wafer, wherein when the photo resist layer has a first larger surface area that is larger in size than a second smaller surface area, a first amount of gas is added into the processing chamber when the first larger surface area is exposed as compared to when the second smaller surface area is exposed which requires a second amount of gas being added to the processing chamber, the first amount of gas being less than the second amount of gas, and vice versa, the second amount of gas being larger than the first amount of gas;
• maintaining said homogeneous etchant across said entire semiconductor wafer by controlling an amount of said hydrocarbon gas added to said processing chamber;
• etching a gate in said gate layer by contacting said gate layer with said homogeneous etchant;
• and
• simultaneously, depositing a passivation layer over all exposed surfaces during said etching using said homogeneous etchant having said uniform concentration of hydrocarbons to provide uniform etching results.