Method for making semiconductor light detection devices
A semiconductor light detection device fabrication technique is provided in which the cap etch and anti-reflection coating steps are performed in a single, self-aligned lithography module.
1. A method for making a semiconductor light detection device comprising the steps of:
providing a wafer comprising a substrate and a semiconductor light detection device overlying the substrate, wherein the semiconductor light detection device comprises a surface comprising a front surface field region and a cap layer overlying the front surface field region;
patterning the cap layer with a photoresist in a cap etch pattern using photolithography, wherein the cap etch pattern defines contact areas and window regions between the contact areas;
etching away the cap layer in the window regions to expose the front surface field region;
applying an anti-reflection coating over the exposed front surface field region and over the photoresist; and
removing the photoresist using a liftoff procedure to expose the contact areas.
2. The method of claim 1 , wherein each of the steps of claim 1 occur without intervening steps.
3. The method of claim 1 , wherein intervening steps occur between the wafer-providing step and the patterning step.
4. The method of claim 1 , comprising, after the removing step, applying a metal grid over the contact areas wherein a width of the contact areas is greater than a width of the metal grid.
5. The method of claim 1 , comprising, after the removing step, applying a metal grid over the contact areas, wherein a width of the contact areas is less than a width of the metal grid.
6. The method of claim 1 , comprising, after the removing step, applying a metal grid over the contact areas wherein a width of the contact areas matches a width of the metal grid.
7. The method of claim 1 , wherein removing the photoresist comprises only using a liftoff procedure.
8. The method of claim 1 , wherein the anti-reflection coating comprises a stack of dielectric layers.
9. The method of claim 1 , comprising, after the removing step, applying a metal grid over the contact areas.
10. The method of claim 1 , comprising, after the removing step, applying a metal grid only over the contact areas.
11. The method of claim 1 , comprising, after the removing step, applying a metal grid over the contact areas and over a portion of the window regions.
12. A semiconductor light detection device fabricated by the steps of:
providing a wafer, wherein the wafer comprises:
a substrate and a semiconductor light detection device overlying the substrate, wherein a top region of the semiconductor light detection device comprises a front surface field region and a cap layer overlying the front surface field region;
patterning the cap layer with a photoresist in a cap etch pattern using photolithography, wherein the cap etch pattern defines contact areas and window regions between the contact areas;
etching the cap layer in the window regions according to the cap etch pattern to expose the front surface field region in the window regions;
applying an anti-reflection coating over the exposed front surface field regions and over the photoresist; and
removing the photoresist using a liftoff procedure to expose the contact areas, wherein the anti-reflection coating covers the front surface field regions in the window regions.
13. The device of claim 12 , comprising, after the removing step, applying a metal grid over the contact areas, wherein a portion of the metal grid is on top of the anti-reflection coating.