A novel in-line automated metrology for photolithography

A control scheme based on the multiblock PLS (MBPLS) model for multi-stage processes (or serially connected processes) is developed. MBPLS arranges a large number of variables into meaningful blocks for each stage of the large-scale system. Two control design strategies, course-to-course (CtC) and within-stage (WS) controls, are proposed for the re-optimization design in the whole multistage course. In CtC, MBPLS control and optimization are done by applying feedback from the finished output quality when one course for all stages is done. It utilizes the information from the current course to improve quality of the next one. In WS, the MBPLS-based re-optimization strategy is developed to explore the possible adjustments of the future inputs at the rest of the stages in order to fix up the disturbances just in time and to maintain the product specification when the current course is finished. The proposed technique is successfully applied to two simulated industrial problems, including a photolithography sequences and a reverse osmosis desalination process, and the advantages of the proposed method are demonstrated.

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“…The model was developed by Leang et al [17,18]. In this photolithography operation, three steps are needed.…”

Section: Illustrative Examplesmentioning

confidence: 99%

Development of MBPLS based control for serial operation processes

Chen

Tsai

2009

Korean J. Chem. Eng.

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“…In order to study a~, principle component regression as described in (15)(16)(17)(18)(19) is used. Subsets of the original measurement data are formed using an increasing number of principle components (PC's).…”

Section: Experimental Analysismentioning

confidence: 99%

RF sensing for real-time monitoring of plasma processing

Garvin¹,

Grizzle²

1998

The 1998 International Conference on Characterization and Metrology for ULSI Technology

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A novel sensing system based on the microwave resonance probe is compared to standard RF metrology. The system uses an antenna in the glow discharge to excite the bulk plasma at a frequency range of 30MHz to 1 GHz. Standard RF metrology is implemented by measuring the fundamental and five harmonics of the RF power signal. An experiment varying power, pressure, CF4 and O2 is constructed. Using a subset of the data to regress a model, standard RF sensing reconstructs the experimental variables with a best average R 2 of 0.586 at a high model coefficient variance (a~), whereas the novel sensing system results in a best average R 2 of 0.804 and an order of magnitude lower ~r~.

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“…To characterize the state of the wafer between each photolithography step, we have chosen to monitor the following parameters: resist thickness (T res ) and photoactive compound concentration (PAC) after the spin-coat and bake step; PAC after exposure; and photoresist pattern linewidth, commonly called critical dimension (CD) after the develop step [14]. While the initial process models of the spin-coat and bake and the exposure steps have been developed through statistically designed experiments, the develop model is based on the physical models embedded in the photolithography simulator SAMPLE [15].…”

Section: Photolithography Equipment Modelsmentioning

confidence: 99%

A control system for photolithographic sequences

Leang

Thomson

et al. 1996

IEEE Trans. Semicond. Manufact.

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The goal of our control system is to improve the reliability, accuracy, and economy of operation of a sequence of interrelated processes. We achieve this task by using well known, rigorous statistical techniques to continuously monitor process parameters, detect out-of-control equipment, and then optimally adjust relevant machine inputs to bring the process back on target. We have implemented the supervisory control system on the photolithography sequence in the Berkeley Microfabrication Laboratory, where it has been conclusively proven that the supervisory control system increases significantly the capability of the entire process. The supervisory control algorithms, consisting of feedback and feed-forward control, multivariate, model-based statistical process control (SPC), and automated specification management algorithms, are independent of machine and/or process, and can be applied to any semiconductor manufacturing sequence.

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A novel in-line automated metrology for photolithography

Cited by 19 publications

References 12 publications

Development of MBPLS based control for serial operation processes

Development of MBPLS based control for serial operation processes

RF sensing for real-time monitoring of plasma processing

A control system for photolithographic sequences

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