NDLI: Improved photoresist integrity by UV photostabilization for high dose, high energy ion implants

Content Provider	IEEE Xplore Digital Library
Author	Rubin, L. Whiteside, D. Norton, C. Stevenson, A. Ukah, C.
Copyright Year	2000
Description	Author affiliation: Axcelis Technol., Beverly, MA, USA (Rubin, L.)
Abstract	High energy ion implantation applications are moving beyond the original low dose requirements of retrograde and triple wells. Collector regions for bipolar and BiCMOS circuits are increasingly formed by high energy implantation. Compared to the previous method of low energy implantation followed by epitaxial layer growth, high energy implantation saves both process steps and cost. Since collectors require low resistivity to give high output currents, relatively high implant doses (2/spl times/10/sup 14/cm/sup -2/-2/spl times/10/sup 15/cm/sup -2/) are needed for a successful epi-replacement process. In the MeV energy range, softbaked photoresist is very susceptible to lifting and popping at doses >2/spl times/10/sup 14/ cm/sup -2/, causing resist failure and high particle contamination. We examined the stability of 2.7-3.5 /spl mu/m photoresist during phosphorus implantation at energies of 900-1200 keV. Photoresist pretreatment with heat and UV light prior to implantation greatly increases the dose that can be implanted before resist hardening or lifting occurs, as compared to hardbaked or softbaked pretreatment. These results are explained in terms of UV-induced cross-linking of the polymer chains in the resist. Heating the resist to >200/spl deg/C during UV treatment is crucial for maximizing resist integrity, a high oxygen ambient is also beneficial. Our results indicate that UV pretreatment is an important process technology for moderate and high dose MeV implants.
Starting Page	817
Ending Page	820
File Size	578095
Page Count	4
File Format	PDF
ISBN	0780364627
DOI	10.1109/IIT.2000.924279
Language	English
Publisher	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Publisher Date	2000-09-17
Publisher Place	Austria
Access Restriction	Subscribed
Rights Holder	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subject Keyword	Resists Implants Ion implantation BiCMOS integrated circuits Epitaxial layers Costs Conductivity Contamination Stability Polymers
Content Type	Text
Resource Type	Article

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