Chemical-mechanical polish method using an undoped silicon glass stop layer for polishing BPSG
 A method using chemical-mechanical polishing for planarizing a BPSG layer 30 using a overlying Undoped Silicate Glass (USG) cap layer 40 comprising: PA1 (a) form a BPSG layer 30 over the semiconductor structure 12; the BPSG layer 30 over the periphery area 16 having a first thickness; PA1 (b) form a cap layer 40 composed of undoped silicon glass (USG) over the BPSG layer 30; the cap layer has a thickness that is at less than half of the first thickness of the BPSG layer; the top surface of the cap layer 40 in the cell area 14 is higher than the top surface of the BPSG layer 30 in the periphery area 16; PA1 (c) chemical-mechanical polish the cap layer 40 and the BPSG layer 30 over the cell area using the cap layer 40 over the periphery area 16 to retard the chemical-mechanical polish process when the top surface of the BPSG layer 30 over the cell area 14 is even with the cap layer 40 over the periphery area 16; and the cap layer 40 remains over the Periphery area 16. 
Taiwan Semiconductor Manufacturing Company
H
H01L
inventional
Chung-Long Syun-Ming
Chang Jang