Tracking control method and electron beam writing system
AssigneeNuFlare Technology, Inc.
InventorHideo Inoue
Life of this patent
Estimating the term…
Abstract
Control data for a main deflector is calculated based on position data that specifies the position of a region to be irradiated with the electron beam on the subfield, data on the number of all beam shots on the subfield, data on a time required for all the beam shots, and stage data that specifies the position of the stage. When the number of beam shots on one of the divided subfield sections reaches the obtained number of the beam shots on each of the divided subfield sections, a writing process proceed to a writing operation to be performed on another one of the divided subfield sections based on the direction of the movement of the stage.
Claims9
A tracking control method comprising the steps of:
- reading positional data that specifies a position to be irradiated with an electron beam, said position being located in a subfield on a mask blank placed on a stage of an electron beam writing system, data on the number of all beam shots to be performed onto said subfield, and data on the time required for all the beam shots;
- reading stage data that specifies a position of said stage at which tracking control needs to be performed for deflecting by a main deflector an electron beam shot toward said subfield on said mask blank while said stage is moved continuously, the deflection being such that said electron beam is deflected onto a desired position in said subfield on said mask blank placed said continuously moving stage;
- calculating control data for said main deflector based on said positional data and said stage data when said mask blank reaches a region in which a shot operation can be performed;
- calculating the number of divided subfield sections by dividing said time required for all the beam shots by a time unit during which a shot operation can actually be performed in said subfield and the number of divided beam shots by dividing said number of all the beam shots by said number of divided subfield sections;
- and
- performing a tracking operation in which after voltage settlement for said main deflector, the number of beam shots is counted with the commencement of a shot operation for a divided subfield section and in which said shot operation is shifted to a next divided subfield section in accordance with the movement of said stage after said counted number of beam shots reaches said number of divided beam shots, wherein
- until the entire shot operations are performed for all the divided subfield sections, said steps of reading said stage data, calculating said control data, calculating said number of divided beam shots, and performing said tracking operation after voltage settlement for said main deflector are repeatedly performed in the mentioned order.
An electron beam writing system comprising tracking control means for deflecting by a main deflector an electron beam onto a subfield on a mask blank placed on a continuously moving stage, said tracking control means comprising:
- storage means for storing in a correlated manner positional data that specifies a position in said subfield to be irradiated with an electron beam, data on the number of all beam shots to be performed onto said subfield, and data on the time required for all the beam shots;
- stage control means for controlling the speed at which said stage moves, measuring the position of said stage, and generating stage data that specifies said position of said stage;
- control data calculation means for calculating control data for said main deflector based on said positional data and said stage data after said mask blank reaches a region in which a shot operation can be performed;
- and
- division processing means for dividing said time required for all the beam shots by a time unit during which a shot operation can actually be performed in said subfield to obtain the number of divided subfield sections and for dividing said number of all the beam shots by said number of divided subfield sections to obtain the number of divided beam shots, wherein
- said division processing means comprises tracking processing means for performing a tracking operation in which said tracking processing means counts, after voltage settlement for said main deflector, the number of beam shots with the commencement of a shot operation for a divided subfield section and in which said tracking processing means shifts said shot operation to a next divided subfield section in accordance with the movement of said stage after the counted number of beam shots reaches said number of divided beam shots.
Dependencies are inferred from the claim text.