Title :
A case study in a 100/spl times/reduction in sodium ions in a 0.8 /spl mu/m BiCMOS process using triangular voltage sweep
Author :
Anderson, Larry ; Parikh, Suketu ; Nagalingam, Samuel ; Haidinyak, Chris
Author_Institution :
Silicon Syst. Inc., Santa Cruz, CA, USA
Abstract :
This case study shows how to use Triangular Voltage Sweep (TVS) to reduce Na and K in the backend of a triple-metal BiCMOS process from 10/sup 12/ ions/cm/sup 2/ to 10/sup 10/ ions/cm/sup 2/. TVS is compared to Bias Temperature Stress (BTS) techniques. While Capacitance-Voltage plots are good monitors for bulk contamination (metal, deposited oxide, etc.), data is presented which shows that TVS is superior for detecting surface-introduced mobile ions (photoresist, solvent strip, etc.). Process integration techniques and issues in the reduction of mobile ions are discussed. When TVS structures are put on product-like wafers, the mobile ions can be measured accurately and repeatably within 10 minutes of completing the process step-no alloy is required! Finally, the use of Ammonium Fluoride solutions to reduce the surface mobile ions are discussed.
Keywords :
BiCMOS integrated circuits; chemical analysis; impurities; integrated circuit measurement; integrated circuit metallisation; integrated circuit reliability; photoresists; surface contamination; 0.8 mum; TiW-AlCu:Na,K; photoresist; positive mobile ionic contamination; process integration techniques; product-like wafers; solvent strip; surface-introduced mobile ions; triangular voltage sweep; triple-metal BiCMOS process; BiCMOS integrated circuits; Capacitance-voltage characteristics; Pollution measurement; Resists; Solvents; Stress; Strips; Surface contamination; Temperature; Voltage;
Conference_Titel :
Integrated Reliability Workshop, 1995. Final Report., International
Conference_Location :
Lake Tahoe, CA, USA
Print_ISBN :
0-7803-2705-5
DOI :
10.1109/IRWS.1995.493574
