Two step etch back process having a convex and concave etch prof

Details Two step etch back process having a convex and concave etch prof Two step etch back process having a convex and concave etch prof

1996-01-11

1997-06-17

Powell, William

Adhesive bonding and miscellaneous chemical manufacture

Delaminating processes adapted for specified product

Delaminating in preparation for post processing recycling step

1566361, 1566431, 216 38, 437228PL, 437238, H01L 2100

Patent

active

056393458

ABSTRACT:
A novel method for improving the etch back uniformity for inter-metal-dielectric planarization was accomplished. Conventional single etch backs use a high polymer chemistry gas mixture (CF.sub.4 /CHF.sub.3) to etch back the planar spin-on-glass (SOG) layer to a conformal insulating barrier layer over a patterned metal. The polymer producing etch gas eliminates micro-loading effects by providing the required selectivity (about 1.6) between the insulating barrier layer and SOG for good planarization, but results in poor etch back uniformity (about 12 to 15%) across the wafer when the SOG is etched. The improved method, of this invention, uses a partial first etch back in a downstream etcher using CF.sub.4 /O.sub.2 having a etch rate that decreases from center to edge of wafer, thereby forming a convex SOG etch rate profile. The remaining SOG layer is then etched to the insulating barrier layer in the CF.sub.4 /CHF.sub.3 etch gas having an etch rate that increases from center to edge of wafer. The characterisic convex etch rate profile of the first etch back compensates for the second etch back (concave etch rate profile) resulting in excellent total etch back uniformity (about 4%), while the second etch back in CF.sub.4 /CHF.sub.3 provides the required selectivity for planarization.

REFERENCES:
patent: 4775550 (1988-10-01), Chu et al.
patent: 5366850 (1994-11-01), Chen et al.

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