Method of forming an isolation film in a semiconductor device
The present invention relates to an isolation film in a semiconductor device and method of forming the same. An isolation film is formed in a doped region of a peripheral region, in which the doped region is isolated from a deep well region of a cell region and the isolation film is thicker than an isolation film of the cell region so that a parasitic transistor is not generated and a leakage current can be prevented.
1. A method of forming an isolation film in a semiconductor device, comprising the steps of:
providing a semiconductor substrate in which a cell region, a peripheral region and a boundary region of the cell region and the peripheral region are defined;
performing a first ion implant process to form a deep well region in a predetermined region of the cell region and a first doped region in a predetermined region of the boundary region;
performing a second ion implant process to form a well region shallower than the deep well region within the deep well region of the cell region and a second doped region within the first doped region, thereby defining a doped region having the first doped region and the second doped region in the boundary region;
performing a patterning process on predetermined regions of the cell region and the peripheral region to form a first trench having a first depth;
performing a patterning process to expose a predetermined region of the peripheral region in which the first trenches is formed, and forming a second trench having a second depth deeper than the first depth only in the peripheral region; and
forming an insulating film for trench burial only within the trenches of the result, thereby forming an isolation film having a first depth in the cell region, an isolation film having a second depth in the peripheral region, and an isolation film having a dual depth, which has the isolation film of the first depth and the isolation film of the second depth at the same, in the boundary region.
2. The method as claimed in claim 1 , further including the step of performing an ion implant process to expose a predetermined region of the deep well region and a predetermined region of the peripheral region, thus forming a well region in a region adjacent to the shallow well region within the deep well region, and a well region for peripheral region in the peripheral region, after the first ion implant process is completed.
3. The method as claimed in claim 1 , further including the step of performing an ion implant process to expose the cell region and the peripheral region adjacent to the doped region, thereby forming a field stop well in the cell region and the peripheral region adjacent to the doped region, respectively, after the second trench formation process is completed.
4. The method as claimed in claim 1 , wherein the doped region is separated from the well regions formed in the cell region and the peripheral regions.
5. The method as claimed in claim 1 , wherein the first ion implant process or the second ion implant process is implanted with the N type ion.
6. The method as claimed in claim 1 , wherein the doped region formed by means of the first ion implant process or the second ion implant process is formed only using a N type ion.
7. A method of forming an isolation film in a semiconductor device, comprising the steps of:
providing a semiconductor substrate in which a cell region, a peripheral region and a boundary region of the cell region and the peripheral region are defined;
performing a first ion implant process to expose predetermined regions of the cell region and the boundary region of the cell region and the peripheral region, thereby forming a first well region in the cell region and the first doped region in the boundary region;
performing a second ion implant process to expose predetermined regions of the cell region and the peripheral region on the result on which the first ion implant process is performed, thereby forming a second well region in the cell region where the first well region is formed and a third well region in the peripheral region;
performing a third ion implant process to expose regions other than the region in which the second well region is formed in the cell region and the first doped region on the result on which the second ion implant process is performed, thereby forming a fourth well region in a region adjacent the second well region and a second doped region in the first doped region, whereby the doped region is defined at the boundary region;
performing a patterning process on predetermined regions of the cell region and the peripheral region in the results on which the third ion implant process is performed, thereby forming a first trench having a first depth;
performing a patterning process to expose a predetermined region of the peripheral region in the results in which the first trench is formed, thereby forming a second trench, which has a second depth deeper than the first depth, only in the peripheral region;
performing a fourth ion implant process to expose the cell region and the peripheral region adjacent to the doped region formed at the boundary portion in the result where the second trench is formed, thereby forming field stop wells in the cell region and the peripheral region adjacent to the doped region; and
forming an insulating film for trench burial only within the first and second trenches of the result, thereby forming an isolation film having a first depth in the cell region, an isolation film having a second depth in the peripheral region, and an isolation film having a dual depth, which has the isolation film of the first depth and the isolation film of the second depth at the same, in the boundary region.
8. The method as claimed in claim 7 , wherein the region formed in the second ion implant process has a depth shallower than that of the region formed in the first ion implant process.
9. The method as claimed in claim 7 , wherein the region formed in the second ion implant process has a depth similar than that of the region formed in the first ion implant process.
10. The method as claimed in claim 7 , wherein the doped region is separated from the well regions formed in the cell region and the peripheral regions.
11. The method as claimed in claim 7 , wherein the first ion implant process or the third ion implant process is implanted with a N type ion.
12. The method as claimed in claim 7 , wherein the second ion implant process is implanted with a P type ion.
13. The method as claimed in claim 7 , wherein the doped region formed by means of the first ion implant process or the third ion implant process is formed using only a N type ion.