Methods for forming trench isolation
View Patent ↗A method of forming an isolation film in a semiconductor device is disclosed. The disclosed method includes performing a patterning process on a predetermined region of a semiconductor substrate in which a patterned pad film is formed, forming a trench defining an inactive region and an active region, forming a liner film on the entire surface including the trench, forming an insulating film for trench burial only within the trench, stripping the remaining liner film formed except for the inside of the trench and the patterned pad film formed below the liner film, forming a sacrificial film on the entire surface, and performing a polishing process on the entire surface in which the sacrificial film is formed until the semiconductor substrate of the active region is exposed, thereby forming the isolation film having no topology difference with the semiconductor substrate of the active region.
1. A method of forming an isolation film of a semiconductor device, comprising:
forming a patterned pad film comprising a pad nitride film on a semiconductor substrate;
forming a trench through the patterned pad film defining an inactive region and an active region;
forming a liner film on the resulting structure;
forming an insulating film in the trench;
stripping the liner film disposed outside of the trench and on top of the patterned pad film leaving liner film disposed inside the trench and in sidewalls of the pad film intact;
forming a sacrificial film on the resulting structure; and
performing a dry etch process on the resulting structure until the semiconductor substrate of the active region is exposed, thereby forming the isolation film having an upper surface that is coplanar with the semiconductor substrate of the active region, comprising performing the dry etch process using a gas having a high selectivity ratio between the sacrificial film and the insulating film for trench burial.
2. The method as claimed in claim 1 , further comprising forming a wall oxide film on sidewalls of the trench after the trench is formed and before the liner film is formed.
3. The method as claimed in claim 1 , wherein the liner film comprises a nitride liner film.
4. The method as claimed in claim 1 , wherein the forming the insulating film within the trench comprises forming the insulating film on the resulting structure on which the liner film is formed, and then performing a polishing process until the pad film is exposed.
5. The method as claimed in claim 1 , wherein the stripping of the liner film disposed outside of the trench and on top of the patterned pad film further comprises stripping the liner film formed on sidewalls of the trench to a predetermined depth while stripping the pad film to form moats at an interface between the inactive region and the active region.
6. The method as claimed in claim 5 , wherein the sacrificial film fills the moats formed at the interface between the inactive region and the active region.
7. The method as claimed in claim 1 , wherein the sacrificial film is a sacrificial oxide film that is formed by a deposition method selected from the group consisting of chemical vapor deposition (CVD) and physical vapor deposition (PVD), or is a growth process in an oxygen atmosphere.
8. The method as claimed in claim 1 , wherein the sacrificial film comprises a sacrificial oxide film formed by a dry oxidization process or a wet oxidization process using H 2 and O 2 gas at a pressure of about 10 Torr to about 100 Torr for about 3 hours to about 5 hours.
9. The method as claimed in claim 1 , wherein the dry etch process is performed using a mixed gas of CH 3 gas and CF 4 gas at high bias power of 200 W.