Stitching methods using multiple microlithographic expose tools
View Patent ↗A method for producing a device in one or more layers of patternable material disposed over a substrate uses multiple exposure tools having different resolution limits and maximum expose field sizes. An abutting field pattern is exposed and stitched in one layer of patternable material using one exposure tool and a first mask. A periphery pattern is then exposed in the same layer or in a different layer of patternable material using a second exposure tool and a second mask. The maximum expose field of the first exposure tool is smaller than a size of the device while the maximum expose field of the second exposure tool is at least as large as, or larger, the size of the device so that the combination of the stitched abutting field pattern and the periphery pattern forms a complete pattern in the patternable material.
1. In the production of a device, a method of forming an intermediate structure using a layer of photosensitive material disposed over a substrate, the method utilizing (i) a first exposure tool having a first maximum expose field smaller than a size of the device, (ii) a second exposure tool having a second maximum expose field larger than the first maximum expose field and at least the size of the device, (iii) a first mask defining one or more unit-cell patterns, and (iv) a second mask defining a periphery pattern for at least partially surrounding a plurality of the unit-cell patterns, the method comprising:
utilizing the first exposure tool, exposing the layer of photosensitive material through the first mask in a plurality of different locations such that, after the first exposure, each subsequent exposure exposes, in the layer of photosensitive material, one of the unit-cell patterns abutting at least one of the previous unit-cell patterns, thereby forming an abutting field pattern in the layer of photosensitive material;
utilizing the second exposure tool, exposing the layer of photosensitive material through the second mask to form the periphery pattern in the layer of photosensitive material at least partially surrounding the abutting field pattern;
developing the layer of photosensitive material to remove a portion thereof; and thereafter, utilizing unremoved portions of the layer of photosensitive material as a mask for a semiconductor process, thereby defining the intermediate structure.
2. The method as in claim 1 , wherein the semiconductor process comprises etching or dopant implantation.
3. The method as in claim 1 , wherein (i) the photosensitive material comprises positive photoresist, and (ii) developing the photosensitive material removes the portion thereof exposed to light through at least one of the first mask or the second mask.
4. The method as in claim 1 , wherein (i) the photosensitive material comprises negative photoresist, and (ii) developing the photosensitive material removes the portion thereof not exposed to light through the first mask or the second mask.
5. The method as in claim 1 , wherein a numerical aperture of the first exposure tool is between 0.35 and 1.0.
6. The method as in claim 1 , wherein a numerical aperture of the second exposure tool is less than 0.35.
7. The method as in claim 1 , wherein a numerical aperture of the second exposure tool is less than 0.35.
8. In the production of a device, a method of forming an intermediate structure using a first layer of photosensitive material and a second layer of photosensitive material disposed over a substrate, the method utilizing (i) a first exposure tool having a first maximum expose field smaller than a size of the device, (ii) a second exposure tool having a second maximum expose field larger than the first maximum expose field and at least the size of the device, (iii) a first mask defining one or more unit-cell patterns, and (iv) a second mask defining a periphery pattern for at least partially surrounding a plurality of the unit-cell patterns, the method comprising:
forming the first layer of photosensitive material over the substrate;
utilizing the first exposure tool, exposing the first layer of photosensitive material through the first mask in a plurality of different locations such that, after the first exposure, each subsequent exposure exposes, in the first layer of photosensitive material, one of the unit-cell patterns abutting at least one of the previous unit-cell patterns, thereby forming an abutting field pattern in the first layer of photosensitive material;
developing the first layer of photosensitive material to remove portions thereof;
forming the second layer of photosensitive material over the developed first layer of photosensitive material;
utilizing the second exposure tool, exposing the second layer of photosensitive material through the second mask to form the periphery pattern in the second layer of photosensitive material at least partially surrounding the abutting field pattern defined in the first layer of photosensitive material;
developing the second layer of photosensitive material to remove portions thereof; and thereafter, utilizing unremoved portions of the first layer of photosensitive material and unremoved portions of the second layer of photosensitive material as a mask for a semiconductor process, thereby defining the intermediate structure.
9. The method as in claim 8 , wherein the semiconductor process comprises etching or dopant implantation.
10. The method as in claim 8 , wherein (i) the first and second layers of photosensitive material comprise positive photoresist, and (ii) developing the first and second layers of photosensitive material removes the portions thereof exposed to light through at least one of the first mask or the second mask.
11. The method as in claim 8 , wherein (i) the first and second layers of photosensitive material comprise negative photoresist, and (ii) developing the first and second layers of photosensitive material removes the portions thereof not exposed to light through the first mask or the second mask.
12. The method as in claim 8 , wherein a numerical aperture of the first exposure tool is between 0.35 and 1.0.