Method and apparatus for determining endpoint of semiconductor element fabricating process
Standard patterns of differential values of interference light that correspond to a predetermined step height of the first material being processed and standard patterns of differential values of interference light that correspond to a predetermined remaining mask layer thickness of the material are set. These standard patterns use wavelengths as parameters. Then, the intensities of interference light of multiple wavelengths are measured for a second material that has the same structure as the first material. Actual patterns with wavelength as parameter are determined from differential values of the measured interference light intensities. Based on the standard patterns and the actual patterns of the differential values, the step height and the remaining mask layer thickness of the second material are determined.
1. A method of processing a semiconductor wafer comprising:
a step of setting a standard pattern consisting of a time differential value of an interference light for each of multiple wavelengths from a first film to be processed overlying a second film that corresponds to a predetermined film process quantity of the first film;
a step of etching a same structure on the semiconductor wafer as the first film overlying the second film, measuring an intensity of an interference light for each of the multiple wavelengths from the first film and determining an actual pattern consisting of a time differential value of the measured interference light intensity for each of the multiple wavelengths;
a step of determining a remaining thickness of the first film based on the standard pattern consisting of time differential values and the actual pattern consisting of time differential values; and
a step of etching the first film remaining after a determination of the thickness of the first film reaching a predetermined value with a changed etching condition during a predetermined time period.
2. A method of processing a semiconductor wafer according to claim 1 , wherein:
the changed etching condition is a condition under which a material of the second film is not easily etched.
3. A method of processing a semiconductor wafer according to claim 2 , further comprising:
a step of exterminating the remaining thickness of the first film based on a recurrent analysis using an old etch quantity of the first film obtained in the step of determining the remained thickness of the first film.
4. A method of processing a semiconductor wafer according to claim 1 , further comprising:
a step of exterminating the remaining thickness of the first film based on a recurrent analysis using an old etch quantity of the first film obtained in the step of determining the remained thickness of the first film.
5. A method of processing a semiconductor wafer according to claim 1 , wherein
the second film is the film with a different in-plane thickness, and said standard pattern and actual pattern consists of the interference lights from a thick portion of the second film.
6. A method of processing a semiconductor wafer according to claim 5 , wherein:
the changed etching condition is a condition under which a material of the second film is not easily etched.
7. A method of processing a semiconductor wafer according to claim 6 , further comprising:
a step of exterminating the remaining thickness of the first film based on a recurrent analysis using an old etch quantity of the first film obtained in the step of determining the remained thickness of the first film.
8. A method of processing a semiconductor wafer according to claim 5 , further comprising:
a step of exterminating the remaining thickness of the first film based on a recurrent analysis using an old etch quantity of the first film obtained in the step of determining the remained thickness of the first film.