Index table and drive mechanism for a chemical mechanical planarization machine

In a processing machine including a plurality of stations for processing workpieces, rotatable index table means for properly positioning said workpieces for transfer to and from said processing stations, said index table means including an outside diameter portion having belt engagement means formed thereon, and a drive mechanism for effecting incremental rotation of said index table means, said drive mechanism including a continuously circulating belt which mates with said belt engagement means, wherein said belt engagement means comprise gear teeth configured to mate with grooves formed in said belt and wherein said index table means includes a ring-shaped table surrounding a central opening, an upper table support ring which is disposed below and supports said table, and a lower gear ring fixed underneath said support ring, said gear teeth being formed in said lower gear ring.