Rectangular substrate for imprint lithography and making method
A rectangular substrate is prepared by providing a starting rectangular substrate having front and back surfaces and four side surfaces as ground, and pressing a rotary polishing pad perpendicularly against one side surface under a constant pressure, and relatively moving the rotary polishing pad and the substrate parallel to the side surface, for thereby polishing the side surface of the substrate. In the imprint lithography, the rectangular substrate is capable of controlling compression and pattern shape at a high accuracy and thus transferring a complex pattern of fine feature size to a recipient.
1. A method for preparing a rectangular substrate for use in imprint lithography, comprising the steps of:
providing a starting rectangular substrate having front and back surfaces and four side surfaces as ground, and
pressing a rotary polishing pad perpendicularly against one side surface of the substrate under a constant pressure, and relatively moving the rotary polishing pad and the substrate parallel to the side surface, for thereby polishing the side surface of the substrate,
wherein the side surface of the substrate includes a longitudinal central region and longitudinal edge regions,
the moving speed of the relative parallel movement of the rotary polishing pad and the substrate is faster when the center of the rotary polishing pad is positioned at the longitudinal edge region of the substrate side surface than when the center of the rotary polishing pad is positioned at the longitudinal central region of the substrate side surface.
2. The method of claim 1 wherein the moving speed of the relative parallel movement is changed in accordance with protrusions and recessions on the substrate side surface.
3. The method of claim 2 wherein the moving speed is faster at protrusions than at recessions on the substrate side surface.
4. The method of claim 1 , further comprising the step of relatively moving the rotary polishing pad and the substrate in a transverse or width direction of the substrate side surface, for thereby polishing the side surface.
5. The method of claim 4 , wherein the rotary polishing pad and the substrate are relatively moved in the transverse or width direction while the rotary polishing pad and the substrate are relatively moved along the side surface, keeping the polishing pad in contact with the substrate side surface.
6. The method of claim 1 wherein after one side surface of the substrate has been polished, the substrate is rotated 90°, a next side surface is polished, and these steps are repeated until all four side surfaces of the substrate are polished.
7. The method of claim 1 , further comprising the step of grinding the back surface of the substrate to form a recess or channel, before or after the step of grinding the side surfaces, or after the step of polishing the ground side surfaces.
8. The method of claim 7 , wherein the ground recess or channel has a side wall and a bottom wall, the method further comprising the step of polishing the side and bottom walls of the recess or channel as ground.
9. The method of claim 8 wherein the step of polishing the side and bottom walls of the recess or channel as ground includes keeping a working portion of a rotary polishing tool in contact with the side and bottom walls under independent constant pressures.
10. The method of claim 1 , wherein the starting rectangular substrate has curvilinear corners formed by grinding and connecting adjoining ones of the side surfaces, and chamfers between the front and back surfaces, formed by grinding, and the side surfaces, and the curvilinear corners and chamfers are polished to a mirror-like finish.