Nobuyoshi Deguchi

Performance of the FPA-7000AS7 1.35 NA immersion exposure system for 45-nm mass production

Canon has developed an immersion exposure tool, the FPA-7000AS7 (AS7), with the industrys highest NA of 1.35. This paper reports on its performance. The AS7s projection lens achieves ultra-low aberration with total RMS of less than 5 mλ and flare of less than 0.5%. The resolution capability is 37 nm with k1 = 0.259, and DOF of 0.8 μm was obtained owing to the ultra-low aberration and low flare. Regarding focus performance, a 3σ value of 19.3 nm for Lstage and 16.1nm for R-stage were attained in a whole area. The result of CD uniformity of 1.91nm (3σ) was obtained across the wafer with a total of 4032 measurement points. Distortion was 3.9 nm at the worst value. On the other hand the most critical issue of immersion is defects, so the nozzle, lens and stage must be cleaned to reduce defects. The result of defect evaluation of the AS7 was an average of 0.042 defect/cm2 from 25 wafers in a lot and average 0.046 defect count/cm2 from long-term defect evaluation for two months. From these results, we are confident that the AS7 is capable of 45-nm node device production.

Immersion exposure tool for 45-nm HP mass production

Canon has renewed its platform of exposure tools. The new platform, the FPA-7000, is designed to cover multiple generations. The lens performance of the FPA-7000AS5 achieves less than 6m&lgr;, while that of the AS7 is estimated to be less than 4m&lgr;. The illumination performance meets the target required for the 45nm node. The in-situ aberration monitor, called iPMI, attains the measurement repeatability of 1.45m&lgr;. Focus and overlay units have improved process robustness. A solution tool for optimization is introduced to be connected with the FPA-7000. Moreover, latest studies of immersion, such as nozzle pressure, temperature control and defect inspection result are reported, and we also discuss the possibility of high-refractive-index immersion.

Mask blanks warpage at 130-nm node

Semiconductor device technology is now making transition from 150 to 130 nm node. Lithography tools for 130 node that employ KrF and ArF as light sources have finished being developed. Also, mask drawing and inspection tools are ready. However, for actual processes, there is an issue to be solved from realistic DOF or overlay accuracy acquisition point of view.

150-nm generation lithography equipment

Lithography by step-and-scan exposure is expected to be the mainstream for semiconductor manufacturing below 180 nm resolution patterns. We have developed a scanner for 150 nm features on either 200 mm or 300 mm wafers. For this system, the synchronous stage system has been redesigned which makes it possible to improve imaging performance and overlay accuracy. A new 300 mm wafer stage enhances productivity while weighting almost the same as the stage for 200 mm wafers. The mainbody mechanical frame incorporates reactive force receiver system to counter the inertial energy and vibrational issues associated with high speed wafer and reticle stage scanning. This report outlines the total system design, new technologies and performance data of the Cannon FPA-5000ES2 step-and-scan exposure tool developed for the 150 nm generation lithography.

Development status of a 157-nm full-field scanner

157 nm lithography has made further progress over the past year, steadily advancing towards the realization of the 65 nm era. In particular, exposure tools have moved on to the assembly phase, with new functions and performance now under evaluation. This paper presents our technical progress in our 157nm full field exposure tool, focusing on two key technologies: projection optics and environmental control with highly purified gasses. The high NA projection optics were designed to meet accelerating demands for smaller geometries. A catadioptric system with a line-selected laser was chosen to solve the problem of chromatic aberrations. The birefringence effect caused by CaF2 has been reduced to acceptable levels by clocking and combining <111> and <100> oriented crystals. Polishing and optical coatings consisting of glass materials were completed at targeted accuracy. At the present time, assembly and tuning of the projection optics is being performed. A simulation based on the inspection data from each production step predicts that the desired image performance will be attained. The total efficiency of the exposure system is expected to be higher than previously announced, due to the improvement of both CaF2 transmittance and AR/HR coatings. One of two keys issues in environmental control is to purge the projection optics which are permanently sealed. Purging performance was tested using a mockup of the projection optics. The second issue is to purge the areas around reticles and wafers which are continually carried into and out of the exposure system. Using the actual platform, the wafer and reticle purging performance was evaluated. It has been demonstrated that both of our purging systems are effective in keeping the environment at minimum contamination levels. This contributes to the increase of throughput.