Aggressive 193nm optical lithography solutions have in turn led to increasingly complex model-based OPC methodologies. This complexity married with the inevitable march of Moore's Law has produced a figure count explosion at the mask writer level. Variable shaped beam equipment manufacturers have tried to mollify the impact of this figure count explosion on the write time by the introduction of new technologies such as increased beam current density, faster DAC amplifiers and more efficient stage algorithms. Despite these efforts, mask manufacturers continue to explore ways of increasing writer throughput and available capacity. This study models the impact of further improvements in beam current density and settling times. Furthermore, this model will be used to prescribe the necessary improvement rates needed to keep pace with the shot count trends extending beyond the 45nm node.
Lithography results using spatially-filtered coherent EUV radiation are presented. These experiments were done using a new 10× Schwarzschild optic and other significant upgrades for high stability and throughput of the system. Included are both single- and multiple-pitch images. A chemically-amplified EUV resist is shown performing at dense 50-nm linewidths and loose 25-nm features. High resolution polymers (HSQ and PMMA) were also tested and demonstrate dense 40-nm linewidths, which are the smallest 1:1 multi-pitch features attempted at this time.
EUV photoresists must be developed that meet the stringent patterning requirements for the next-generation of microprocessors (32nm node and beyond). In this paper we will address the ability of EUV photoresists to meet the material targets specs (MTS), such as CD resolution, line width roughness (LWR), photo sensitivity, and absorbance. The challenges of meeting CD resolution and line width roughness specs are not restricted to EUV lithography, but also need to be met by other technologies (193nm, 157nm, and 193 immersion technologies). However, EUV photoresists encounter the unique challenge of meeting these MTS with higher photospeeds than any other lithographic technology due to EUV source requirements. The design of EUV resists that meet all of the MTS and have sufficiently high photospeeds is very challenging. In this paper, we will present experimental results of EUV photoresists patterning results from the 10X tool at Sandia National Lab, and the F2X at Lawrence Berkeley National Lab. Data on resolution, LWR, photo sensitivity, and absorbance are included. Finally we address the capabilities of current EUV resists to meet the patterning requirements, and highlight areas where acceleration is required to meet the Intel roadmap.
By using a spatial frequency doubling method, our 10x Schwarzschild optic can print high-contrast features at 50 nm with low line-edge roughness (LER). In this paper, we also present new techniques for evaluating photoresist at EUV wavelengths using our system. One method is used to determine the ultimate resolution of a resist through linewidth vs. dose measurements. Another is to investigate line-edge roughness properties by varying the aerial image contrast of a pattern. A novel filtering method is proposed that would allow multiple contrasts to be printed in a single exposure. This is achieved by varying the duty cycle and line/space transmission levels of the object grating. Since this is a single exposure technique it would allow for mroe controlled contrast tests when evaluating resists.
We demonstrate the use of a 13.4-nm wavelength, 10x-demagnification Schwarzschild optical system to expose high-resolution test patterns, extending well beyond the conventional resolution limit to dense feature sizes of 50 nm and below. We have successfully used a spatial frequency doubling technique to print equal line and space patterns with line widths as small as 30 nm. Simulations show that by using the fully extended numerical aperture, the system may achieve line widths as small as 12 nm. This configuration shows great potential for use in evaluating the ultimate performance and extendibility of resist materials for EUV lithography.