Fabricating method of insulator
View Patent ↗A fabricating method of an insulator for replacing a gate structure in a substrate by the insulator. The fabricating method includes the step of providing a substrate including a first buried gate structure. The first buried structure includes a first trench embedded in the substrate and a first gate filling in the first trench. The first trench has a first depth. Then, the first gate of the first buried structure is removed. Later, the substrate under the first trench is etched to elongate the depth of the first trench from the first depth to a third depth. Finally, an insulating material fills in the first trench with the third depth to form an insulator of the present invention.
1. A fabricating method of an insulator, comprising:
providing a substrate comprising a first buried gate structure and a second buried gate structure, wherein said first buried structure comprises a first trench having a first depth and embedded in said substrate, a first gate dielectric layer disposed on the inner sidewall of said first trench, a first gate filling said first trench;
forming a patterned mask covering said second buried gate structure and exposing said first buried gate structure having said first depth;
removing said first gate of said first buried structure by using said patterned mask as a mask;
etching said substrate under said first trench so that said first trench is elongated from said first depth to a third depth;
removing said patterned mask; and
forming an insulating material which fills said first trench of said third depth to form an insulator.
2. The fabricating method of an insulator of claim 1 , wherein said second buried gate structure comprises a second trench having a second depth and said third depth is greater than said second depth.
3. The fabricating method of an insulator of claim 1 , wherein said first depth is as deep as said second depth.
4. The fabricating method of an insulator of claim 1 , wherein said first buried structure further comprises a gate cap layer disposed in said first trench and above said first gate before etching said substrate under said first trench.
5. The fabricating method of an insulator of claim 4 , further comprising:
removing said gate cap layer before removing said first gate of said first buried structure.
6. The fabricating method of an insulator of claim 4 , wherein said gate cap layer and said first gate dielectric layer both have silicon oxide.
7. The fabricating method of an insulator of claim 1 , wherein silicon nitride is disposed on said substrate.
8. The fabricating method of an insulator of claim 1 , wherein two doping regions are disposed in said substrate and adjacent to two sides of said insulator.