Method of manufacturing a semiconductor device
In a manufacturing step in which a structure of target of screening is formed on a semiconductor substrate in the middle of manufacturing process before a semiconductor device is finished, screening of potential defects of a gate insulating film is performed for each wafer at one time so that the semiconductor device is caused to appear as an initial defective product when the finished semiconductor device is subjected to an electrical characteristic test. Provided are a semiconductor device, and a method of manufacturing a semiconductor device which enables reliable screening of potential defects in a short period of time.
1. A method of manufacturing a semiconductor device, the semiconductor device having a gate insulating film and a gate electrode film on a semiconductor substrate of a wafer, the method comprising:
forming a first gate insulating film on the semiconductor substrate of the wafer;
forming a first gate electrode film on an entire surface of the semiconductor substrate of the wafer, the semiconductor substrate of the wafer including the first gate insulating film;
screening, after the forming a first gate electrode film, the first gate insulating film by generating a potential difference between the first gate electrode film which is formed on the entire surface of the semiconductor substrate of the wafer, and a back surface of the semiconductor substrate of the wafer to apply an electric field to the first gate insulating film;
determining the semiconductor substrate of the wafer which has been subjected to the screening;
patterning the first gate electrode film after the determining the semiconductor substrate;
removing, after the patterning the first gate electrode film, the first gate insulating film which is formed on the entire surface of the semiconductor substrate of the wafer from at least a region in which a second gate insulating film is to be formed;
forming, after removing the first gate insulating film, the second gate insulating film on the semiconductor substrate of the wafer;
forming a second gate electrode film on the entire surface of the semiconductor substrate of the wafer, the semiconductor substrate of the wafer including the second gate insulating film;
screening, after the forming a second gate electrode film, the second gate insulating film by generating a potential difference between the second gate electrode film which is formed on the entire surface of the semiconductor substrate of the wafer, and the back surface of the semiconductor substrate of the wafer to apply an electric field to the second gate insulating film;
determining the semiconductor substrate of the wafer which has been subjected to the screening; and
patterning the second gate electrode film after the determining the semiconductor substrate.
2. The method of manufacturing a semiconductor device according to claim 1 , further comprising repeating a plurality of times:
removing, after the patterning the second gate electrode film, a gate insulating film that is previously formed;
forming a new gate insulating film on the semiconductor substrate of the wafer;
forming a new gate electrode film on the entire surface of the semiconductor substrate of the wafer which includes the new gate insulating film;
screening, after the forming a new gate electrode film, the new gate insulating film by generating a potential difference between the new gate electrode film which is formed on the entire surface of the semiconductor substrate of the wafer, and the back surface of the semiconductor substrate of the wafer to apply an electric field to the new gate insulating film;
determining the semiconductor substrate of the wafer which has been subjected to the screening; and
patterning the new gate electrode film after the determining the semiconductor substrate.
3. The method of manufacturing a semiconductor device according to claim 1 , further comprising forming the gate insulating film a plurality of times so that the second gate insulating film has a thickness smaller than a thickness of the first gate insulating film or a gate insulating film that is formed later has a smaller thickness.
4. The method of manufacturing a semiconductor device according to claim 1 , further comprising applying a screening voltage for the gate insulating film that is formed a plurality of times so that a screening voltage for the second gate insulating film is higher than a screening voltage for the first gate insulating film or a screening voltage for a gate insulating film that is formed later is higher.