A case study on modeling and optimizing photolithography stage of semiconductor fabrication process

Abstract

Photolithography in the semiconductor fabrication process is the core stage that determines the quality of semiconductor chips. The fabrication process is a batch process that causes variation in the quality of chips; thus, uniformity has always been an important goal of the process. This research is a case study on optimizing the photolithography stage to improve uniformity and the target achievement of critical dimension, a quality measure of semiconductor chips. The case study finds the optimal setting of input variables in photolithography by applying multivariate normal linear modeling with operational data obtained by sampling during manufacturing. The predicted performance of the optimal setting is found to be close to the limit of improvement estimated based on the model. For practitioners, several issues that can be considered for better optimization are also provided.

Multiresponse Optimization and Pareto Frontiers

“…MSO problems that have been developed under the RSM framework comprise, in general, responses fitted by second order polynomial models, 3 input variables and small design spaces. Spherical regions, whose radius depends on the experimental design used, are usually considered so the search space is not complex, although convex and nonconvex regions may exist in the Pareto frontier.…”

Synthesis, Dielectric and Electrical Properties of Silver-Polymer Nanocomposites

“…The top down approach involves bulk materials and decrease them into nano-sized particles by using physical/chemical and mechanical processes [34]. The top-down approach is also used for the fabrication of many materials including semiconductor industry [35], in this approach metal oxide semiconductor field effect transistor (MOSFET) are imprinted onto a silica wafer by lithography based technique [36]. On the other hand, the preparation in bottom-up method requires single atoms and molecules into larger nanostructures to achieve nano-size particles [34].…”

Chemical Structure–Physicochemical Property Relationships of Copolymers Utilizable for Negative-Tone Photoimaging via Chemical Amplification

“…A large increase in the degree of integration through the miniaturization of a semiconductor is a significant issue in the semiconductor manufacturing industry. , The key process in high-performance semiconductor devices is photolithography, which uses UV light sources. − The wavelength of the light has been continuously decreased to form finer patterns based on Rayleigh’s equation: − G-line using 436 nm, I-line using 365 nm, deep UV (DUV) including a KrF excimer laser of 248 nm and an ArF excimer laser of 193 nm, and extreme UV (EUV) with 13.5 nm, which has recently attracted much attention for a next-generation lithographic tool. − In addition to the change in light source, photoimaging materials for the fabrication of photopatterns have been improved with a smaller critical dimension. In particular, chemically amplified resists (CARs) have been most widely used as patterning materials for DUV lithography as they can achieve outstanding sensitivity with patterning capability in double-digit nanometer dimensions. − Furthermore, CAR has been extended to EUV lithography to realize extremely small dimensions for sub-20 nm technical nodes. − …”