Method of measuring shot shape and mask

• US 8,339,614 B2
• Filed: 03/23/2006
• Issued: 12/25/2012
• Est. Priority Date: 03/25/2005
• Status: Active Grant

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Kondo, Shinjiro
• Primary Examiner(s): Chowdhury, Tarifur
• Assistant Examiner(s): AKANBI, ISIAKA O
• Application Number:
  US11/886,665
• Publication Number:
  US 20090033948A1
• Time in Patent Office: 2,469 Days
• Field of Search: 356/601, 356614-620, 356/124, 356399-401, 356/498, 356/508, 355/53, 430/394
• US Class Current: 356/616
• CPC Class Codes: G03F 1/44 Testing or measuring features, e.g. grid patterns, focus monitors, sawtooth scales or notched scales
• CPC Class Codes: G03F 7/706 Aberration measurement
• CPC Class Codes: G03F 7/70616 Monitoring the printed patterns
• CPC Class Codes: G03F 7/70633 Overlay, i.e. relative alignment between patterns printed by separate exposures in different layers, or in the same layer in multiple exposures or stitching
• CPC Class Codes: G03F 9/7076 Mark details, e.g. phase grating mark, temporary mark
• CPC Class Codes: G03F 9/7084 Position of mark on substrate, i.e. position in (x, y, z) of mark, e.g. buried or resist covered mark, mark on rearside, at the substrate edge, in the circuit area, latent image mark, marks in plural levels

Abstract

A method of measuring shot shape includes sequentially exposing a substrate with main scale marks (32) in compliance with a predetermined map, and forming a reference grid including a plurality of the main scale marks (32) arranged in the predetermined map in at least one shot region, exposing a shot for measuring, via a projection optical system, that includes a plurality of auxiliary scale marks (34) arranged in the predetermined map in the shot region, measuring a relative positional relationship between adjacent main scale marks (32), measuring an amount of deviation between the main scale marks (32) and the auxiliary scale marks (34), and correcting the reference grid based on the relative positional relationship, and calculating a shot shape of the shot for measuring based on the corrected reference grid and the amount of deviation.

Claims

1. A method of measuring shot shape comprising:

sequentially exposing a substrate with main scale marks in compliance with a predetermined map, and forming a reference grid including a plurality of the main scale marks arranged in the predetermined map in at least one shot region;

exposing a shot for measuring, via a projection optical system, that includes a plurality of auxiliary scale marks arranged in the predetermined map in the shot region;

measuring a relative positional relationship between adjacent main scale marks in the shot region exposed on the substrate;

measuring an amount of deviation between the main scale marks and the auxiliary scale marks; and

correcting the reference grid based on the measured relative positional relationship so that the corrected reference grid does not include positioning error of the substrate caused in the process of forming the reference grid, and calculating a shot shape of the shot for measuring based on the corrected reference grid and the amount of deviation.

2. The method of measuring shot shape according to claim 1, wherein, simultaneous to exposing the substrate with the main scale marks, surrounding marks, which are used in measuring a relative positional relationship between a main scale mark of the plurality of main scale marks and another main scale mark of the plurality of main scale marks formed adjacent to the main scale mark of the plurality of main scale marks, are formed between the main scale mark and the other main scale mark, and

each one of the surrounding marks individually surrounds a separate one of the main scale marks.

3. The method of measuring shot shape according to claim 1, wherein the reference grid is formed by multiple exposures of main scale mark groups, constituted by grouping the plurality of main scale marks, in the shot region exposed on the substrate.

4. The method of measuring shot shape according to claim 3, wherein each main scale mark group is formed such that the plurality of main scale marks in the main scale mark group are arranged in a row.

5. The method of measuring shot shape according to claim 1, wherein the calculation of the shot shape includes correcting the reference grid by using a statistical method of processing the relative positional relationship that is measured.

6. A mask comprising:

at least one main scale mark;

auxiliary scale marks that are arranged in a grid formation along a first direction and a second direction orthogonal to the first direction, each of the auxiliary scale marks and the main scale mark are superimposed to indicate a relative amount of deviation between them; and

at least one pair of surrounding marks arranged such as to sandwich the main scale mark, the pair of surrounding marks including a main surrounding mark, and an auxiliary surrounding mark that is separated by a grid interval of the auxiliary scale mark from the main surrounding mark, and the auxiliary surrounding mark and the main surrounding mark are superimposed to indicate a relative amount of deviation between the main surrounding mark and the auxiliary surrounding mark,

wherein the main surrounding mark and the auxiliary surrounding mark are located at a same distance from the main scale mark, the distance is half of the grid interval of the auxiliary scale mark.

7. The mask according to claim 6, wherein a plurality of the main scale marks are arranged in a row along the first direction;

and

the main surrounding mark and the auxiliary surrounding mark are arranged in separation along the second direction.

8. The mask according to claim 7, which is used by being mounted on a scanning exposure apparatus, the marks being arranged such that the second direction becomes a scanning direction of the scanning exposure apparatus.