在先进的单晶片光刻胶处理系统上使用独特的无溶剂相流体进行超音速增强光刻胶去除

Introduction 

Removal of photoresist materials (resist stripping) is very straightforward in theory, but  can be difficult and complicated in practice. Classical methods have included SPM  (sulfuric peroxide module) /piranha, ozone and UV ozone. Solvent based fluids such as  n-methylpyrollidone (NMP), Acetone, Dimethylsulfoxide (DMSO) and  Tetramethalammonium (TMAH) have all been applied to this process in various forms  and combinations. Typically solvents have been combined with temperature or gases (1)  to enhance throughput and reduce the damage caused by swelling in thick PR scenarios.  Dynamic dispense systems have also been applied to the standard solvent combinations  including aerosol sprays (2) and physical activation of the solvents through acoustic  energy (3) to help reduce process times and damage induces through PR film swelling.  Many dry and wet dry combinations have been implemented using various Plasma and  CO2 combinations. All of the legacy methods include hazardous and toxic materials  and/or high equipment expense as well as multi-step process control complexity. The  stripping process becomes even more challenging by factors such as thick resist, crosslinked resist or sensitive metals or materials under the resist. This study was carried out  In order to determine feasibility of the use of a unique phase-fluid based photoresiststripper in commercial semiconductor resist removal process steps. Due to their highly  dynamic inner structure, phase-fluids penetrate into the polymer network of photoresists  and lift the material from the surface as opposed to the surface or boundary reaction of a  solvent solution. (4) As these water-based stripping fluids are non-aggressive, non-toxic,  and require no special handling, the ability to apply them to industry standard resists will  result in a reduction of toxic and dangerous chemistries and the environmental impact of  their disposal.

This work reflects the combination of two distinct mechanisms applied to the photo  resist stripping process, Phase-fluid (intelligent fluid®) and Single Wafer Megasonics.  Phase-Fluid (intelligent fluid®) (4) intelligent fluids® consist of a heterogeneous  mixture of two immiscible liquids that form a stable micro-emulsion. There is a balance  established between the separation forces that keeps the components of the emulsion in  constant motion or shape changing on a nano basis. When this very physically dynamic  fluid is exposed to a film such as photo resist, the low surface energy allows for the  penetration of very small gaps in the polymer surface, and the eventual forcing of the  resist layer from the substrate. The film removal from the substrate is in the form of an  actual physical lift-off separation and not a dissolution or etching of the film. Dilution of  the Phase-Fluid is not proscribed as the equilibrium of the micro emulsion will become  unbalanced and the forces will be neutralized immediately stopping any reaction. The  intelligent fluid® formulas have proven to be very robust and stable in both storage time,  temperature and shipment.

Table 2 lists the photoresists employed in the balance of this study. They are  identified as PR-1 through PR-5. Five different formulations of intelligent fluids® were  tested on all photoresist samples and under all process conditions. For the purpose of this  study, the intelligent fluids® formulations are identified as if-A through if-E.