Composite back-etch/lift-off stencil for proximity effect minimization

摘要

This composite back-etch/lift-off stencil method avoids the uncontrolled changes in the properties of contacts in small devices caused by the close proximity of the lift-off resist stencil to the contact area during the precleaning, surface preparation and metal deposition processes. This method limits the area of the wafer exposed to back-etching and thus restores the freedom of choice of contact metallurgy. Back-etching is only applied in the areas of the wafer near to the contact holes; lift-off techniques are used for the rest of the integrated circuit.