Nonvolatile split gate memory cell having oxide growth

A method of making a split gate nonvolatile memory cell on a semiconductor layer, comprising:

• forming a gate dielectric over the semiconductor layer;
• depositing a first layer of polysilicon gate material over the gate dielectric;
• etching the first layer of polysilicon gate material to remove a portion of the first layer of polysilicon gate material over a first portion of the semiconductor layer and to leave a select gate portion having a sidewall adjacent to the first portion;
• applying a treatment over the semiconductor layer to reduce a relative oxide growth rate of the sidewall to the first portion, wherein the applying the treatment is performed prior to the step of etching;
• growing oxide on the sidewall to form a first oxide on the sidewall and on the first portion to form a second oxide on the first portion after the applying the treatment;
• forming a charge storage layer over the first oxide and along the second oxide;
• and
• forming a control gate over the second oxide and adjacent to the sidewall.