Flash memory device

A method of forming a semiconductor device, comprising

• providing a silicon-on-insulator (SOI) substrate comprising a semiconductor bulk substrate, a buried oxide layer formed on said semiconductor bulk substrate and a semiconductor layer formed on said buried oxide layer;
• forming a fully depleted silicon-on-insulator (FDSOI) transistor device in a first area of said SOI substrate;
• forming a flash transistor device on and in said semiconductor bulk substrate in a second area of said SOI substrate that is electrically isolated from said first area;
• and
• forming a read transistor device on and in said semiconductor bulk substrate in said second area of said SOI substrate;
• wherein forming said FDSOI transistor device comprises forming a high-k gate dielectric layer on said semiconductor layer and forming a metal gate layer over said high-k gate dielectric layer;
• wherein forming said flash transistor device comprises forming a floating gate from a part of said semiconductor layer, forming an insulating layer on said floating gate and forming a control gate comprising a metal gate layer on said insulating layer;
• and
• wherein forming said read transistor device comprises removing a part of said semiconductor layer and a part of said buried oxide layer in a region of said SOI substrate, thereby exposing a surface of a part of said semiconductor bulk substrate, forming a high-k gate dielectric layer on said exposed surface of said semiconductor bulk substrate and forming a read gate electrode over said high-k gate dielectric layer.