Nano-scale particles have a strong tendency to agglomerate due to their small size and high surface area. Agglomerate structures come in a variety of shapes and sizes; nonuniformity can present major challenges for nano-material processing.
The laser-based mask repair system has progressed from an attractive high-return investment to a critical production tool necessary for manufacturing defect-free reticles. In fact, since the early 1980s Quantronix' DRS I and DRS II laser repair systems have become the industry standards for the production of defect-free reticles.
As the semiconductor industry moves into the 1990's, a new generation of photomasks, both conventional and phase-shift types with smaller critical dimensions and multiple layers, requires that more information be encoded onto the masks. Increased mask production cost and tighter defect tolerances have created the critical need for new high sensitivity pattern inspection and defect repair equipment for chrome and phase-shift masks. We are actively investigating new and improved technologies to meet the future repair demands of the maskmaking community, including methods and devices to improve chrome repair, to modify phase-shift materials and to increase overall system utility and throughput.
The strengths of laser mask repair systems are well known, although misconceptions may exist about the limitation of the laser technique, especially concerning repair accuracy which is currently specified in the DRS II as ±0.15 um (2 sigma). Recent experimental results in our laboratory indicate that a laser micromachining technique should be able to achieve an edge accuracy for the repair of opaque defects on feature edges of ±0.05 um (3 sigma). This capability will satisfy the edge defect specifications for future generations of 5x optical reticles which will be used for manufacture of 64M and beyond DRAM chips.
In this paper the laser processing results for chrome and candidate phase-shift materials will be discussed; the discussion will begin with some background information on Quantronix' activities with lasers and laser repair systems.
We present the initial clinical results of the use of the pulsed
2.15 micron thulium-holmium-chromium:YAG (THC:YAG) laser for
gastrointestinal endoscopic surgery. This pulsed mid-infrared laser
was designed to fit the clinical need for precisely controllable
tissue vaporization which can be delivered via a flexible delivery
system. We obtained an Investigational Device Exemption from the FDA
and in December 1988 we began our clinical program. Using the
THC:YAG laser via a flexible fiberoptic endoscope, we have
successfully performed vaporization or excision of sessile neoplastic
polyps of the upper and lower gastrointestinal tract of 12 patients.
Our initial experience has confirmed our expectation that this new
laser system can provide the endoscopic surgeon with a technical
alternative not matched by currently available laser systems.