George G. Gifford

Insitu infrared diagnostics of particle forming etch plasmas

In situ Fourier transform infrared absorption techniques are employed to characterize the gas‐phase plasma species and etch products present in halocarbon containing plasmas which produce particles. A correlation is demonstrated between the distribution of these species and the extent of particle formation as measured by laser light scattering. The effects of the presence of silicon and the addition of oxygen on both the plasma species distribution and the degree of light scattering are also characterized. Additionally, x‐ray photoelectron spectroscopy (XPS) and infrared (IR) microscopic techniques are employed to determine the chemical composition of the particulate material which is found on the silicon wafer after etching.

Applications of optical emission spectroscopy in plasma manufacturing systems

Optical ernissn)n spectroscopy (OES) is an established laboratory diagnostic technique for plasma processes. By detecting light from the electronic transitions of atoms and molecules it is possible to identify and monitor the chemical species in a plasma. This technique has been extended to semiconductor manufacturing to determine the endpoint of plasma processes. The production of semiconductor devices relies heavily on plasma etching and deposition processes. Because OES is a fairly simple technique its use as a continuous tool and process hionitor has been investigated. Ultimately this technique could provide immediate feedback for automatic adjustment of individual process parameters. This embodiment has been referred to as adaptive process control.

Fabrication of 64-Mb DRAM using x-ray lithography

This paper describes results achieved from the fabrication of 64Mb DRAM chips using x-ray lithography for the gate level. Three lots were split at the gate level for exposure with either Micrascan 92 at IBMs Advanced Semiconductor Technology Center (ASTC) or x-ray at the Advanced Lithography Facility (ALF) containing a Helios super-conducting storage ring and a Suss stepper. The x-ray mask was fabricated at MMD (Microlithographic Mask Development Facility) as a two-chip mask containing one chip which had zero defects. To achieve adequate overlay performance between the x-ray exposed gate level and previous optically- printed levels, the mask was fabricated with an intentional magnification correction. The alignment scheme for both Suss and Micrascan was first order to an ASM zero level, and second order to each other. Results from the first lot show 90% of the chips tested achieved a +/- 140 nm target for the Suss to Micrascan overlay. Critical dimension control (across wafer and across chip) was measured and found to be comparable between Suss and Micrascan. Electrical performance was comparable to the optical wafers. Chips were fabricated with zero defects in many of the 1 Mb segments. There were also x-ray fabricated chips which demonstrated 63 Mb addressable bits.