Memristors were vertically integrated with CMOS circuits using nanoimprint lithography (NIL), making a transistor/memeristor hybrid circuit. Several planarization technologies were developed for the CMOS substrates to meet the surface planarity requirement for NIL. Accordingly, different integration schemes were developed and optimized. UV-curable NIL (UV-NIL) using a double layer spin-on resists was carried out to pattern the electrodes for memristors. This is the first demonstration of NIL on active CMOS substrates that are fabricated in a CMOS fab. Our work demonstrates that NIL is compatible with commercial IC fabrication process. It was also demonstrated that the memristors are integratable with traditional CMOS to make hybrid circuits without changing the current infrastructure in IC industry.
KRS-XE, a high performance chemically amplified photoresist designed specifically for e-beam mask making applications, has been enhanced to achieve reduced “footing” on chrome oxide surfaces while still maintaining the original lithographic characteristics that make KRS-XE a promising mask making candidate. These attributes include high resolution, superior bake latitudes, high vacuum stability, coated shelf life of greater than 2 months, and, most notably, the absence of a post exposure bake. In conjunction with the footing reduction the requisite sensitivity requirement of <10uC/cm2 with 50 keV exposure tools has been achieved while retaining the robust process latitude previously reported for this resist. Through a careful study of the photoresist formulation components a route to the ultra-high sensitivity of <2.5uC/cm2 at 50 keV has been elucidated which will further enhance throughput, decrease heating effects, and potentially be a suitable resist for e-beam projection lithography (EPL).
KRS-XE is a chemically amplified resist developed to enable electron-beam lithography for mask making at the 100nm node. This material has been shown to provide an excellent process window for mask manufacturing at this node. Characterization of this material using both 50keV raster and 75keV vector scan e-beam exposure systems will be presented. A higher sensitivity version of this material has been developed specifically for a vector, shaped beam 50keV application. Initial mask manufacturing results for this higher sensitivity version of KRS-XE will be presented for 75keV. In addition, recent developments using KRS-XE formulations modified to achieve high sensitivity and improved etch resistance will be discussed.