Eric H. Bokelberg and Michael E. Pariseau, In todays high-volume semiconductor fabs, photolithographic process steps (wafer prime, resist-apply, expose, bake, and develop) are performed in sequence hundreds of times on hundreds of wafers per day to produce well-defined photoresist patterns. In many cases, these litho process steps are combined into one tool, referred to as a photocluster, that links a resist-process track system with an exposure tool. Because lithography plays a critical role in creating device features throughout the semiconductor production operation, accurate, repeatable photocluster performance is vital, and the individual tools are typically monitored by means of numerous tool checks (inspection procedures designed to evaluate specific components of the process). Examples include resist-film-thickness and hot-plate temperature uniformity measurements on the track, and dose-uniformity and focus-control evaluations on the expose tool. Assessment of defect performance is limited to foreign material (FM) particulate inspections through subprocesses such as resist-apply, develop only, or dry-wafer handling. While the individual tool checks ensure that many of the most critical components of the litho process are within established specifications, they are unable to monitor the interactions between components, which can create out-of-spec conditions in the printed pattern even though individual tools are in spec. Consequently, the integrated litho process is also monitored through inspections and measurements of production wafers. In-line product parametric data are sorted by photocluster and displayed in tool-specific statistical process control (SPC) charts. When out-of-control trends are identified, operation of the problem tools is inhibited until the problem can be investigated and resolved. As long as these inspections occur immediately after the litho process, and the products and levels processed on each tool are consistent from day to day (as in a large-volume, single-part-number fab), this approach to photo tool control works reasonably well. However, as fab product loading becomes more varied, with
Products & Services
Semiconductor Cluster Tools
Semiconductor cluster tools and equipment are used to process semiconductor wafers for the production of microelectronic components.
Thin Film Equipment
Thin film equipment uses vacuum processing for the modification of surfaces using CVD, PVD, plasma etching, and thermal oxidation or ion implantation.
Semiconductor Foundry Services
Semiconductor foundry services suppliers design and manufacture semiconductor chips on a contract basis, in prototype to production quantities.
Lithography equipment transfers circuit or device patterns onto a substrate using a patterned mask and a beam of light or electrons to selectively expose a photoresist layer. Overlay metrology systems align the pattern masks or reticules.
MEMS Processing Equipment
MEMS processing equipment is used to create micro-electro-mechanical systems (MEMS) sensors and wafers.
Topics of Interest
and Arwa S. Ginwalla, A technique based on instrumented wafers provides useful data for addressing day-to-day temperature-related concerns in a production fab. ecause of its effects on device...
Chandra Saravanan, Zhuan Liu, Weidong Yang, Matthew F. Swisher, and Anlun Tang, Shrinking device dimensions place aggressive demands on defect detection metrology. As device density and critical...
Intel ramps up EUV litho development, installs 300-mm microexposure system, sets up Extreme-ultraviolet (EUV) lithography has entered the development phase at Intel. The company said in early August...
and Shuba Chandar and Tan Chang Ou, In the competitive semiconductor environment, manufacturers must be able to ramp new processes quickly and maintain high yields during production. Fast ramp-up and...
The construction of a semiconductor wafer fab today is estimated to cost $1 billion to $1.5 billion, and price tags in the $2-billion-plus range are rapidly approaching. These floating...