29 March 2013 Precuring implant photoresists for shrink and patterning control
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Abstract
Polymeric photoresists are readily being used as the stopping layer for ions during implantation processes in manufacturing of integrated circuitry. In order to be compatible for standard optical lithography with deep ultraviolet exposures, the state-of-the-art resists are chemically amplified; as they are for photoresists for etch patterning. Partially deprotected, including patterned, photoresists contain a range of small molecular weight species that are prone to escape the resist if the resist was to be irradiated by additional UV-light, electron beams or ion bombardment. For implant processes in device integration this is becoming progressively the most topical issue for aggressive nodes, where 193 nm compatible resists are progressively turning out to be the new platform for implant lithography. These will shrink significantly during the ion implantation and subsequently produce undesired doping gradients on a length scale comparable to the target feature width. In addition, conventional UV-flood exposure that is common for 248 nm resist platforms is not directly transferrable to 193 nm resists. In this paper, we explore the precuring options available for state-of-the-art implant photoresists for 193 nm lithography, in which we target to reduce the shrinkage during implantation for trench critical dimensions that are relevant for nodes below 20 nm. We present an extensive study comprising of different approaches, including laser-, ion- and electronbased treatments. Each treatment is individually investigated with the aim not only to find a valid pretreatment for shrinkage control during implantation, but also to fundamentally understand what effect alternative pretreatments have on the profile and dimensions of thick photoresists used as implant stopping layers. We find that there are viable options for further process optimization in order to integrate them into device process flows. To this extent, we show the shrink behavior after pretreatment and compare the additional shrink dynamics after implantation.
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Gustaf Winroth, Gustaf Winroth, Erik Rosseel, Erik Rosseel, Christie Delvaux, Christie Delvaux, Efrain Altamirano Sanchez, Efrain Altamirano Sanchez, Monique Ercken, Monique Ercken, } "Precuring implant photoresists for shrink and patterning control", Proc. SPIE 8682, Advances in Resist Materials and Processing Technology XXX, 868207 (29 March 2013); doi: 10.1117/12.2011423; https://doi.org/10.1117/12.2011423
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