Method of manufacturing semiconductor device including forming a t-shape gate electrode

1. A method of manufacturing a semiconductor device, the method comprising the steps of:

forming a buffer layer formed of a dual-layers structure of a buffer oxide film and a buffer nitride film on a semiconductor substrate formed with a certain lower structure;

forming source/drain by performing an ion injection process through the buffer layer after forming the buffer layer, the buffer layer not being etched before forming the source/drain;

defining a gate hole by etching the buffer layer after forming the source/drain;

forming a gate oxide film on the defined gate hole;

forming a gate material to bury the defined gate hole;

forming a T-shape gate electrode through a process of etching the gate material using the buffer nitride film as an etching stop film; and

forming a contact hole after forming an inter-layer dielectric on a resulting structure formed with the T-shape gate electrode.

2. The method according to claim 1 , wherein a photo-resist pattern defining source/drain regions is formed on the buffer layer before the source/drain are formed.

3. The method according to claim 1 , wherein in the step of defining a gate hole by etching the buffer layer, a reverse mask pattern is formed on a top of the buffer layer, and then the gate hole is defined through an etching process using the reverse mask pattern as an etching mask.

4. The method according to claim 1 , wherein the buffer nitride film is used as an anti-reflection coating in an etching process for forming the contact hole.

5. The method according to claim 1 , wherein in the etching process for forming the contact hole, a contact hole can be separately formed in each of the gate electrode and the source/drain to expose a corresponding region.