Strategy of ultra-clean processing program: strategy
The main goal of the ultra-clean processing (UCP) program is to provide solutions for cleaning and contamination control for future generations and to build up basic understanding. The basic understanding provides a solid basis for progress as opposed to a pure experimental approach which typically leads to evolutionary incremental improvements. At the same time, it provides a solid knowledge base to deal with excursions or problems during the manufacturing phase. The models developed allow also for extrapolation towards future technology requirements and trends.
The UCP program consists of several subprograms, some activities have a generic nature, others are more application oriented as illustrated in figure 1. As much as possible topics are dealt with in a generic way. This allows the use of the obtained results for multiple different applications, thus providing better leverage.
Generic subprograms deal with contamination control, contamination metrology, single-wafer cleaning, novel chemistries and particle contamination and removal. Application-specific activities concentrate on high-k metal-gate stacks, novel semiconductor substrates, post I/I photoresist removal and post-low-k etch residue removal.
The program deals with some of the major critical future cleaning requirements such as selective removal of photoresist, particles and other contaminants (from recessed areas) without unacceptable substrate loss or damage to fine patterns (such as gate electrodes).
Also the selective removal of photoresist and residues after etching of low-k dielectrics needs to be established without attacking low-k material, leaving chemicals behind in the pores, degrading the low-k properties or attacking exposed Cu.
Also other critical applications, such as, pre-epi clean without pre-bake and wafer drying of hydro-phobic/phylic patterns and fragile structures, belong to the scope of the program.
Finally in the program also appropriate metrology and test structures are developed to support the cleaning research activities.