Charged particle beam writing method and charged particle beam writing apparatus
In one embodiment, a charged particle beam writing method includes transferring a substrate to a writing chamber of a charged particle beam writing apparatus by use of a transfer mechanism while maintaining each of the writing chamber and the transfer mechanism at a predetermined temperature, calculating correction amounts for charged particle beams based on correction data for charged particle beam irradiation positions each associated with a previously obtained elapsed time from a predetermined starting point in time of transfer of the substrate and the elapsed time at a point in time of irradiation with each of the charged particle beams, and applying the charged particle beams to positions corrected based on the calculated correction amounts for the charged particle beams to write a pattern on the substrate.
1. A charged particle beam writing method comprising:
transferring a substrate to a writing chamber of a charged particle beam writing apparatus by use of a transfer mechanism while maintaining each of the writing chamber and the transfer mechanism at a predetermined temperature;
calculating correction amounts for charged particle beams based on correction data for charged particle beam irradiation positions each associated with a previously obtained elapsed time from a predetermined starting point in time of transfer of the substrate and the elapsed time at a point in time of irradiation with each of the charged particle beams; and
applying the charged particle beams to positions corrected based on the calculated correction amounts for the charged particle beams to write a pattern on the substrate.
2. The method according to claim 1 , wherein the correction data is further based on a total number of times of contact between the substrate and the transfer mechanism or a total time of contact between the substrate and the transfer mechanism.
3. The method according to claim 1 , wherein in response to the elapsed time exceeding a threshold value, the pattern is written on the substrate without calculation of the correction amounts based on the elapsed time.
4. The method according to claim 1 , further comprising:
transferring an evaluation substrate to the writing chamber;
sequentially writing n (n is an integer of 2 or more) evaluation patterns at different positions on a surface of the evaluation substrate such that a plurality of elements of a first evaluation pattern are written at predetermined intervals on the surface of the evaluation substrate and a plurality of elements of a second evaluation pattern are then written at predetermined intervals on the surface of the evaluation substrate; and
measuring positions of the sequentially written first to n-th evaluation patterns,
wherein the correction data is obtained based on a result of the measuring and an elapsed time from a predetermined starting point in time of transfer of the evaluation substrate to a point in time of writing of each of the first to n-th evaluation patterns.
5. The method according to claim 4 , wherein the correction data contains a correction map that is generated for each of the first to n-th evaluation patterns based on the result of the measuring and in which position displacements of writing positions are mapped.
6. The method according to claim 5 , wherein the correction map is generated by using values that are obtained by fitting the result of the measuring of each of the first to n-th evaluation patterns with an exponential function.
7. The method according to claim 4 , wherein the correction data contains factors of a polynomial that approximates position displacements of writing positions calculated for each of the first to n-th evaluation patterns based on the result of the measuring.
8. A charged particle beam writing apparatus comprising:
a transfer mechanism transferring a substrate;
a writing chamber receiving the substrate transferred;
a thermostatic unit maintaining each of the writing chamber and the transfer mechanism at a predetermined temperature;
an elapsed time calculator calculating an elapsed time from a predetermined starting point in time of transfer of the substrate to the writing chamber;
a storage storing correction data for irradiation positions to be irradiated with charged particle beams, the irradiation positions being associated with the elapsed time obtained previously;
a corrector calculating correction amounts for the charged particle beams based on the correction data and the elapsed time at a point in time of irradiation with each of the charged particle beams; and
a writer applying the charged particle beams to positions corrected based on the calculated correction amounts for the charged particle beams to write a pattern on the substrate.
9. The apparatus according to claim 8 , wherein the correction data is further based on a total number of times of contact between the substrate and the transfer mechanism or a total time of contact between the substrate and the transfer mechanism.
10. The apparatus according to claim 8 , wherein in response to the elapsed time exceeding a threshold value, the pattern is written on the substrate without calculation of the correction amounts based on the elapsed time.