Focus measurement method and method of manufacturing a semiconductor device
View Patent ↗In a focus measurement method and a method of manufacturing a semiconductor device relating to the present invention, a focus value is obtained by using a fluctuation where shrinkage of a resist pattern by an electron beam irradiation depends upon the focus value. In the case of obtaining the focus value, the shrinkage of the resist pattern for a focus measurement formed by exposure to be subject for a focus value measurement is measured. The focus value corresponding to the shrinkage is obtained from the pre-obtained focal dependency of the shrinkage. A focal shift length can be defined from a difference between the focus value and a predetermined best focus value.
1. A focus measurement method, comprising the steps of:
preparing a correspondence relationship between a focus value set on an exposure apparatus and a shrinkage of a resist pattern obtained by measuring a dimension of the resist pattern a plurality of times, the resist pattern being formed on a substrate using the exposure apparatus with the focus value;
measuring the dimension of the resist pattern formed on a substrate to be a subject for a focus measurement by exposure using the exposure apparatus with a set focus value the plurality of times;
obtaining the shrinkage of the resist pattern formed by exposure with the set focus value according to the measured result; and
obtaining a focus value corresponding to the obtained shrinkage based upon the correspondence relationship.
2. The focus measurement method according to claim 1 , wherein the dimension of the resist pattern is measured a plurality of times by irradiating an electron beam to the same portion of the resist pattern.
3. The focus measurement method according to claim 2 , wherein the step of obtaining the shrinkage of the resist pattern includes a step of calculating the shrinkage of the resist pattern by the electron beam irradiation from the dimension measured the plurality of times.
4. The focus measurement method of claim 3 , wherein the shrinkage of the resist pattern is calculated by subtracting a value of a final measurement of the dimension from a value of an initial measurement of the dimension.
5. The focus measurement method according to claim 2 , further comprising a step of pre-determining a number of times for measuring the resist pattern based upon a number of times to saturate the shrinkage of the resist pattern caused by the electron beam irradiation.
6. The focus measurement method according to claim 3 , further comprising a step of pre-determining a number of times for measuring the resist pattern based upon a number of times to saturate the shrinkage of the resist pattern caused by the electron beam irradiation.
7. The focus measurement method according to claim 4 , further comprising a step of pre-determining a number of times for measuring the resist pattern based upon a number of times to saturate the shrinkage of the resist pattern caused by the electron beam irradiation.
8. The focus measurement method according to claim 1 , wherein the resist pattern is made of a chemically-amplification resist material.
9. The focus measurement method according to claim 2 , wherein the resist pattern is made of a chemically-amplification resist material.
10. The focus measurement method according to claim 1 , wherein the resist pattern is an isolated line pattern.
11. The focus measurement method according to claim 2 , wherein the resist pattern is an isolated line pattern.
12. The focus measurement method according to claim 8 , wherein the resist pattern is an isolated line pattern.
13. The focus measurement method according to claim 10 , wherein the line pattern width is 0.15 μm or less.
14. The focus measurement method according to claim 11 , wherein the line pattern width is 0.15 μm or less.
15. The focus measurement method according to claim 12 , wherein the line pattern width is 0.15 μm or less.
16. A method of manufacturing a semiconductor device, comprising:
preparing a correspondence relationship between a focus value set on an exposure apparatus and a shrinkage of a resist pattern obtained by measuring a dimension of the resist pattern a plurality of times, the resist pattern being formed on a substrate using the exposure apparatus with the focus value;
measuring the dimension of the resist pattern formed on a substrate to be a subject for a focus measurement by exposure using the exposure apparatus with a set focus value the plurality of times;
obtaining the shrinkage of the resist pattern formed by exposure with the set focus value according to the measured result;
obtaining a focus value corresponding to the obtained shrinkage based upon the correspondence relationship;
obtaining a focal shift length based upon the obtained focus value;
correcting the set focus value set on the exposure apparatus based upon the obtained focal shift length; and
exposing a substrate by the exposure apparatus on which the corrected set focus value is set.
17. The method for manufacturing a semiconductor device according to claim 16 , wherein the corrected set focus value is used for a plurality of substrates contained in a same lot.