Prevention of Metal Penetration
Original Publication Date: 1982-Apr-01
Included in the Prior Art Database: 2005-Feb-09
Contact metals, such as aluminum, can penetrate silicon up to 0.5 micron during low temperature heat treatments, causing device performance to deteriorate completely. A simple way to prevent metal penetration is to deposit a doped epitaxial silicon layer in the contact device area prior to metal deposition. The epitaxial deposition is performed at 700 degrees C in an evacuated capsule containing silicon, dopant and iodine. On top of dielectric layers, doped polysilicon is formed during the epitaxial silicon deposition in the silicon contact hole. Metal contacts can be accomplished by depositing metal on the silicon over the contact opening or by depositing metal on the doped polysilicon outside the contact area.