Contact Alignment Recipes

Back to Lithography Recipes.

Notes

Below is a listing of contact lithography recipes for use with designated aligners. Based on your sample reflectivity, absorption, and surface topography the exposure time parameters may vary. This listing is a guideline to get you started. The recipes are tabulated to give you the values of the key parameters you will need to establish your recipe. For wafer cleaning and preparation including HMDS use, please refer to the cleaning and preparation section in the lithography section of this web site. For best resolution using thin resists, you will need to remove any edge bead before contact and exposure. Also, hard contact mode will give you the most intimate contact between sample and mask, giving the best resolution. Post develop bakes (not listed) are used to make the resist more etch resistant and depend on subsequent processes. Unless otherwise noted, all exposures are done on silicon wafers.

Positive Resist

Unless otherwise noted, bakes are on hot plates and the exposure of the resist is done using no filtering at 7.5 mW/cm2. Power of the lamp is set using the 405 nm (h-line) detector. For the MA-6 aligner, using Channel 1, reduce exposure times by a factor of 2.4.

Negative Resist

Unless otherwise noted, bakes are on hot plates and the exposure of the resist is done using no filtering at 7.5 mW/cm2. Power of the lamp is set using the 405 nm (h-line) detector. In general, many negative resists require post-exposure-bakes (PEB) / flood exposures in order to make the negative tone of the image. All flood exposures are done in broadband light using any contact aligner. Also, because the tone is negative, a shorter first exposure time will result in more undercut, which is desirable for single-layer lift-off processes. Under these conditions more develop time will also give more undercut. For the MA-6 aligner, using Channel 1, reduce exposure times by a factor of 2.4.