TSV CMP processes on bonded wafers

TSV CMP processes on bonded wafers include TSV backside CMP revealing process and TSV Via last CMP process. The patterned and thinned device wafers are temporarily bonded on silicon carrier, which results in huge TTV (total thickness variation). Such TTV makes CMP processes more challenging. In this paper, CMP processes on bonded wafers are studied. Cu and barrier layer are successfully and fully removed, but the variation of underneath oxide layer exists because bonding and subsequent processes change the topography of the bonded wafers.