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The quencher mechanisms in Chemically-Amplified (CA) resists have been investigated. To explain the acid distribution with a variety of acid strengths in the presence of quencher, a new full Acid-Equilibrium-Quencher model (AEQ model) is proposed and examined in solid-model-CA-resist systems. To observe the reactions in the CA resists, real-time Fourier-Transform-Infrared Spectroscopy (FTIR) is employed during post-exposure bake (PEB). The FTIR peaks of the protection groups are detected to measure the reaction kinetics during PEB. The solid-model-CA resists used in this work consist of both a KrF-acetal-type resist with a diazomethane Photo-Acid Generator (PAG) (weaker-photoacid system) and an ArF-ester-type resist with a sulfonium-salt PAG (stronger-photoacid system). The obtained FTIR results are analyzed using conventional Full-Dissociation-Quencher model (FDQ model) and the new AEQ model. The kinetic analysis of the model resists was performed for different quencher loadings. For the weaker-photoacid system, the AEQ model much more accurately predicts the deprotection-reaction kinetics than the FDQ model with the change of quencher content. This suggests the necessity of introduction of the acid-dissociation concept in the case of the weaker photoacid. For the stronger-photoacid system, both the AEQ and conventional FDQ models adequately predict the kinetic results. This shows that the conventional FDQ model is accurate enough to simulate the super-strong photoacid system. Finally, the new AEQ model is introduced in the UC Berkeley STORM resist simulator. Some simulation examples are shown in the paper.

A Process/Device/Design framework called the Parametric Yield Simulator is proposed for predicting circuit variability based on circuit design and a set of characterized sources of variation. In this simulator, the aerial image of a layout is simulated across a predefined process window and resulting non-idealities in geometrical features are communicated through to circuit simulators, where circuit robustness and yield can be evaluate in terms of leakage and delay variability. The purpose of this simulator is to identify problem areas in a layout and quantify them in terms of delay and leakage in a manner in which designers and process engineers can collaborate together on an optimal solution to the problem. The Parametric Yield Simulator will serve as a launch pad for collaborative efforts between groups in different disciplines that are looking at variability and yield. Universities such as Berkeley offer a great advantage in exploring innovative approaches as different centers of key expertise exist under one roof. For example a complementary set of characterization and validation experiments has also been designed and in a collaborative study is being executed at Cypress semiconductor on a 65nm NMOS process flow. This unique opportunity of having access to a cutting edge process flow with relatively high transparency has led to a new set of experiments with contributions from six different students in circuit design, process engineering, and device physics. Collaborative efforts with the device group have also led to a new electrical linewidth metrology methodology using enhanced transistors that could prove useful for process characterization.

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The variation in the printing of nominally identical contacts with electron-beam exposure is used to quantitatively determine the statistical variation in chemically amplified resists (KRS-XE with and without top coat, TOK) and non-chemically-amplified resists (PMMA and HSQ). Uniform 17×23 arrays of 24 and 32nm contacts were exposed at fixed doses with a 100keV electron beam. By looking at data observed from top view scanning electron microscopy images, a normal distribution was fitted to the fraction of contacts that printed versus dose to determine the standard deviation of the distribution relative to the dose at which 50% of the contacts printed. The top coat on KRS-XE increased contact uniformity and reduced the required dose. Quantitative analysis shows that PMMA contained as much noise as the chemically amplified resist systems, KRS-XE and TOK. Except HSQ, this normalized standard deviation ranged from 0.16 to 0.21 which is indicative that the contact hole printing process may be dominated by less than 40 events. HSQ exhibited lower standard deviation values, corresponding to over 1000 effective events.