Method of manufacturing a split gate trench semiconductor comprising a thicker inter-poly oxide, ipo layer and a semiconductor device comprising a thicker ipo layer

A method of manufacturing a split-gate trench in a semiconductor material, the method comprising the steps of:

• providing a gate trench in the semiconductor material, the gate trench having an oxide material provided at a bottom side of the gate trench and provided on a sidewall of the gate trench so that an inside of the gate trench is insulated from the semiconductor material, the gate trench further comprising a polysilicon material provided on top of the oxide material that is provided at the bottom side of the gate trench;
• providing a nitride spacer against the oxide material that is provided at the sidewall of the gate trench;
• growing an inter-poly oxide (IPO) on top of the polysilicon material, wherein the nitride spacer at least reduces growth of IPO at the oxide material provided at the sidewall, wherein IPO is grown preferentially and locally at the oxide material provided at a bottom-end of the nitride spacer;
• and
• removing the nitride spacer.