PEB Temperatures Research Articles

Study on Fabrication Process of SU8 Photoresist Microstructures and Evaluation of Stress Gradient

A fabrication process to manufacture SU8 photoresist microstructures is presented in which BP212 positive photoresist was used as sacrifice layer and SU8 was used as structure layer. No crack has been observed in the obtained microstructures. The relation between PEB temperature and stress gradient in SU8 film has been studied by measuring radii of released SU8 cantilevers made at different PEB temperatures.

PEB bake optimization for process window improvement of mixed iso-dense pattern

We have shown that process effects induced by extending the post-exposure bake temperature in the process flow of chemically amplified photoresists can lead to significant improvements in depth-of-focus (DOF) and exposure latitude (EL) and small geometry printing capability. Due to improved acid dose contrasts and a balanced optimization of acid diffusion in the presence of quencher, PEB temperature increase has enabled the printing of iso and semi-dense space of 0.2 µm and below with a large DOF, using binary masks and 248 nm lithography without expensing the iso-dense bias. The results and findings of a full patterning process in a device flow, with different PEB temperatures as a process enhancement, are presented. The main objective of this study is to demonstrate how, using KrF lithography with binary masks and no optical proximity correction (OPC) nor other reticle enhancement technique (RET), the process latitude can be improved. Lithographic process latitudes, intra-field critical dimension (CD) uniformity and resist profiles of different PEB processes are evaluated. Then, the after-etch profiles are also investigated to ensure the feasibility of this technique.

Negative tone chemically amplified resist formulation optimizations for ultra high-resolution lithography

Starting from the Sumitomo commercial platform NEB-33 resist, three new experimental negative tone chemical amplified resist (CAR) formulations have been developed, to push resolution below 40 nm in direct electron beam lithography. PEB temperatures and times have been optimized between 60 and 100 °C and, respectively, 20 and 120 s. Fourier transform infra red spectra have been performed and allowed us to follow the solvent and PAG concentration in order to optimize processes on all samples. As a consequence, 25-nm isolated lines have been resolved with these new chemical amplified resists.

Factors Affecting the Performance of Chemically Amplified DUV Positive Photoresists.

This paper presents further results on two-component positive-tone chemically amplified DUV resist. A partially deblocked poly(p-vinyl)phenol film is shown to be stable to autocatalytic hydrolysis, unlike other blocked poly(p-vinyl)phenol films. The concept of ‘T-top’ formation through acid loss during the postexposure bake is presented as an additional concern, besides the well known base contamination effect. The activation energy for the deblocking reaction is measured to be 35kcal/mole and the kinetic order for deblocking is 1.9. These resists show better linearity and exposure latitude at lower PEB temperatures such as 70°C, with a resultant substantial photospeed penalty.

Submicron imaging at 248.3nm: A lithographic performance review and initial process performance screening of Megaposit SNR 248-1.0 photo resist.

This paper reviews the initial lithographic performance of the Megaposit® SNR™ 248-1.0 Photo Resist during the imaging of 0.35, 0.40, 0.45, 0.50 and 0.55μm line/space pairs on a 0.42NA/0.5 coherence/ KrF stepper. The test results show that process window overlap can be maintained. to a normalized geometry size of 0.59 k1 for line/space pairs. This degree of overlap is shown to be comparable to a normalized value of 0.76 k1 during the simultaneous imaging of line/space pairs, isolated lines and isolated spaces. This result appears to be consistent with the g-line results published previously1. It is also shown that at the exposure dose required to size the target geometry, the resist induced bias, due to lateral development is negligible and provides the possibility to extend the working resolution to smaller geometries if the intensity minimum of the aerial image can be suppressed. Finally, an additional screening experiment in which soft bake temperat re, post exposure bake temperature, resist thickness and develop time were varied, This latter study suggests that detailed optimization studies should examine lower PEB temperatures, 140C and less, and shorter develop times, 90s and less, at both EMIN and EMAX thicknesses.