Alignment unit and exposure apparatus

An exposure apparatus comprising:

• an alignment unit configured to align a pattern of an original having the pattern and an alignment mark, with an area in an uppermost layer in a plurality of layers of a substrate in transferring the pattern to the area;
• and
• a projection optical system configured to project the pattern of the original onto the substrate after the alignment unit provides an alignment between the pattern of the original with the area of the substrate,
• wherein the alignment unit includes:
• a measurement unit configured to measure a coordinate of a center position of the alignment mark transferred to each layer that is located under the uppermost layer of the substrate;
• and
• a controller configured to determine a target coordinate of the center position of the alignment mark transferred to the uppermost layer of the substrate based on a result of a weighted average that is made by weighting the coordinate of the center position of the alignment mark of each layer of the substrate measured by the measurement unit using as a weight a function inversely proportional to a minimum critical dimension of the pattern of the original formed on each layer of the substrate.

A device manufacturing method comprising to steps of:

• exposing a substrate using an exposure apparatus;
• and
• developing the substrate that has been exposed,
• wherein an exposure apparatus includes:
• an alignment unit configured to align a pattern of an original having the pattern and an alignment mark, with an area in an uppermost layer in a plurality of layers of a substrate in transferring the pattern to the area;
• and
• a projection optical system configured to project the pattern of the original onto the substrate after the alignment unit provides an alignment between the pattern of the original with the area of the substrate,
• wherein the alignment unit includes:
• a measurement unit configured to measure a coordinate of a center position of the alignment mark transferred to each layer that is located under the uppermost layer of the substrate;
• and
• a controller configured to determine a target coordinate of the center position of the alignment mark transferred to the uppermost layer of the substrate based on a result of a weighted average that is made by weighting the coordinate of the center position of the alignment mark of each layer of the substrate measured by the measurement unit using as a weight a function inversely proportional to a minimum critical dimension of the pattern of the original formed on each layer of the substrate.

A device manufacturing method comprising the steps of:

• exposing patterns and alignment marks of an N−1-th layer and an N-th layer on a substrate using an exposure apparatus;
• measuring alignment mark positions of the N−1-th layer and the N-th layer on the substrate that has been exposed
• storing in a memory offset information of the exposure apparatus that has exposed each of the N−1-th layer and the N-th layer on the substrate;
• sending information on the mark alignment positions in the N−1-th layer and the N-th layer which have been stored, and offset information of the exposure apparatus that has exposed each of the N−1-th layer and the N-th layer on the substrate which has been stored, to another exposure apparatus for an exposure of an N+1-th layer;
• determining a target coordinate of a center position of an alignment mark to be exposed in the N+1-th layer using a weighting result that is made by weighting information on the alignment mark positions of the N−1-th layer and the N-th layer which have been obtained and offset information of the exposure apparatus that has exposed each of the N−1-th layer and the N-th layer on the substrate which has been obtained, using as a weight a function inversely proportional to a minimum critical dimension of the pattern in each of the N−1-th layer and the N-th layer;
• exposing the N+1-th layer based on the target coordinate of the center position of the alignment mark which has been determined;
• and
• developing the substrate that has been exposed.