Semiconductor device and method of fabricating the same
A semiconductor device includes a first buried gate structure in a peripheral circuit area of a semiconductor substrate, and a second gate structure formed on the semiconductor substrate. A gate insulating layer of a program transistor is thinly formed to be easily ruptured, and a gate insulating layer of a select transistor is thickly formed to improve reliability of the select transistor.
1. A semiconductor device, comprising:
a first buried gate structure including a first gate insulating layer in a semiconductor substrate of a peripheral circuit area;
a second gate structure including a second gate insulating layer formed on the semiconductor substrate,
wherein a thickness of the second gate insulating layer is less than a thickness of the first gate insulating layer;
wherein the second gate structure includes a conductive layer on the second gate insulating layer; and
wherein the first gate structure includes:
the first gate insulating layer formed in a trench in the semiconductor substrate;
the conductive layer formed on the first gate insulating layer within the trench and having a predetermined thickness; and
a hard mask layer formed on the conductive layer.
2. The semiconductor device of claim 1 , further comprising:
first and second metal contacts coupled to the first gate structure and the second gate structure respectively; and
a third metal contact formed on a drain region or a source region and coupled to the first gate structure.
3. The semiconductor device of claim 1 , wherein the second gate structure is driven as a program gate and the first gate structure is driven as a select gate.
4. The semiconductor device of claim 1 , wherein the thickness of the second gate insulating layer is 20 to 30 Åand the thickness of the first gate insulating layer is 50 to 60Å.
5. The semiconductor device of claim 1 , wherein the thickness of the first gate insulating layer is the same as the thickness of a gate insulating layer formed in a buried gate of a cell area of the semiconductor device.
6. The semiconductor device of claim of claim 1 , wherein a channel is formed below the first gate insulating layer when the second gate insulating layer is ruptured.