Method for forming shallow trench isolation structure
View Patent ↗A method of fabricating a shallow trench isolation structure is disclosed. On a substrate, a pad oxide layer and a mask layer are successively formed. The pad oxide layer, the mask layer and a portion of the substrate are patterned to form a trench. After performing a rapid wet thermal process, a liner layer is formed on the exposed surface of the substrate, including the exposed silicon surface of the substrate in the trench and sidewalls and the surface of the mask layer. An oxide layer is deposited over the trench and the substrate and fills the trench. A planarization process is performed until the mask layer is exposed. The mask layer and the pad oxide layer are removed to complete the shallow trench isolation structure.
1. A method for forming a shallow trench isolation structure, comprising:
providing a substrate;
forming a pad oxide layer and a mask layer successively on the substrate;
patterning the pad oxide layer and the mask layer;
patterning the substrate to form at least a trench in the substrate, using the patterned mask layer as a mask;
forming a first insulating layer over the substrate and filling the trench;
performing an etching back step to remove a portion of the first insulating layer until top comers of the trench are exposed and a top surface of the remained first insulating layer is lower than the pad oxide layer;
performing a rapid thermal process to form an oxide liner layer on an exposed surface of the substrate, including the exposed top corners of the trench;
forming a second insulating layer over the trench and the substrate and filling the trench, after performing the rapid thermal process;
performing a planarization process to the second insulating layer until the mask layer is exposed; and
removing the mask layer and the pad oxide layer to form the shallow trench isolation structure.
2. The method as claimed in claim 1 , wherein the step for forming the pad oxide layer includes a thermal oxidation process and the step for forming the mask layer comprises forming a silicon nitride layer by rapid thermal chemical vapor deposition.
3. The method as claimed in claim 1 , wherein the step of forming the first insulating layer includes high density plasma chemical vapor deposition, and the first insulating layer comprises an oxide layer.
4. The method as claimed in claim 1 , wherein the step for forming the second insulating layer includes high density plasma chemical vapor deposition, and the second insulating layer comprises an oxide layer.
5. The method as claimed in claim 1 , wherein the rapid thermal process is performed at a temperature of about 800° C.-1000° C.
6. The method as claimed in claim 1 , wherein the step for patterning the substrate to form the trench comprises anisotropic etching.
7. The method as claimed in claim 1 , wherein the planarization process includes chemical mechanical polishing.
8. The method as claimed in claim 1 , wherein the step of performing the etching back step includes performing buffered oxide etching.
9. The method as claimed in claim 1 , further comprising forming a liner layer, after patterning the pad oxide layer, the mask layer and the substrate to form at least the trench and before forming the first insulating layer.
10. The method as claimed in claim 1 , further comprising performing a pull-back step by patterning the mask layer and the pad oxide layer to expose a portion of the substrate near edges of the trench, after patterning the pad oxide layer, the mask layer and the substrate to form at least the trench and before forming the first insulating layer.
11. The method as claimed in claim 10 , further comprising forming a liner layer, after the pull-back step and before forming the first insulating layer.