Evaluation of total uncertainty in the dimension measurements using critical-dimension measurement scanning electron microscopes

Mizuno, Fumio

doi:10.1116/1.590387

Cited by 3 publications

(5 citation statements)

References 5 publications

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“…( 6) is much smaller than that of the prediction error using the etch CD bias for lot P,M1 in eq. (7). Figure 9(a) shows the statistical distribution of the prediction error using the etch CD bias for the pilot wafer.…”

Section: Resultsmentioning

confidence: 99%

“…5,6) There is also measurement error caused by instability of the CD measurement tools such as the CD-SEM. 7) Both the longterm process drift and the long-term instability of the CD measurements lead to variations in the process model for APC in the gate plasma etching process and the variations result in gate linewidth variations, even when feedforward control is used. Chemali et al showed that short-term process model variations can be compensated for using feedback control of the process model outputs from the previously processed lot.…”

Section: Introductionmentioning

confidence: 99%

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Evaluation of Errors in Feedback Control Based on Persistence Prediction in Model-Based Process Controller System for Deep Sub-100 nm Gate Fabrication

Goto

Makabe

2006

Jpn. J. Appl. Phys.

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Using model-based advanced process control (APC) in the gate etching process, gate linewidth variations that are caused by variations in the photo resist linewidth are reduced by feedforward control of the photo resist linewidth that is obtained by a critical dimension (CD) measurement tool. Both long-term process drift in the etching process and long-term instability of the CD measurement tool lead to variations in the process model for APC. These process model variations result in gate linewidth variations and are attenuated by feedback control using the etch CD bias from the previously processed lot. We used a lot-to-lot model-based APC system and a critical dimension scanning electron microscope (CD-SEM) in a deep sub-100 nm gate fabrication line to investigate long-term variations in the process model over a period of six months, and to study how much the variations are reduced by feedback control based on persistence prediction methods using the etch CD bias for the pilot wafer from the currently processed lot. The process model uses the linear relationship between the etch CD bias and the gas mixture ratio at the gate linewidth plasma trimming step, and the gradient is almost constant over the term. The spread in the long-term variation in the process model was 8.12 nm. The variation mainly included process drift in the plasma etcher, and the persistence of the etch CD bias in the lot after processing was significantly lost beyond approximately one week. When using feedback control based on the persistence prediction method using the etch CD bias for the pilot wafer from the currently processed lot, the standard deviation of the feedback error was 0.50 nm of 1σ. On the other hand, when calculating feedback control with the lot-mean etch CD bias from the lot processed immediately before the currently processed lot, the standard deviation of the feedback error was estimated to be 0.82 nm of 1σ. When performing feedback with the etching shift value of the pilot wafers, the percentage of lots whose post etch CD value fell within the range of ±1 nm from the target value was higher by 20% than the simulated value of the percentage of lots in which feedback was calculated with the etch CD bias of the previously processed lots.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Evaluation of Errors in Feedback Control Based on Persistence Prediction in Model-Based Process Controller System for Deep Sub-100 nm Gate Fabrication

Goto

Makabe

2006

Jpn. J. Appl. Phys.

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“…After removing the systematic and gross errors, the measurement data vector y(), y()=[y i , i=1,2,..., 15], is listed as:…”

Section: Experimental Testingmentioning

confidence: 99%

“…Arri et al [14] discussed a number of practical issues, such as the calibration at different levels of accuracy, the evaluation of traceability levels throughout a measurement hierarchy, and inter-laboratory comparison. Mizuno [15] discussed total uncertainty in critical dimension measurement with expressions of the uncertainty. Phillips [16] proposed a method to extend the current ISO guide [1] to deal with uncorrected measurement bias in roundness measurement.…”

Section: Introductionmentioning

confidence: 99%

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Estimation of non-statistical uncertainty in precision measurement using grey system theory

Gao

Wang

Tao

et al. 2003

The International Journal of Advanced Manufacturing Technology

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A new uncertainty assessment method is proposed to characterize non-statistical uncertainties in precision measurement. The proposed method is based on grey system theory to address the problem involved in uncertainty assessment where the sampling size is small and the distribution of the data is unknown. The advantage of the proposed approach is that the requirements of the statistics based methods are removed. In the proposed method, an accumulated true size vector and an accumulated measurement data vector are established to reduce the effects of the errors in the measurement and in the numerical calculation. The uncertainty assessment is based on the l ¥ norm of the difference between the accumulation of the sorted measurement data vector and that of the true size vector. A number of computational and experimental tests were carried out. The results demonstrated the effectiveness and consistency of the proposed method in non-statistical uncertainty assessment, compared with the existing methods.

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Technique for estimating the angle of incidence and depth of focus of an electron beam

Mizuno

Amemiya

Taniguchi

2005

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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In order to cope with the problems with scanning electron microscopes for semiconductor manufacturing, the ability to measure the focal depth and incident angle of an electron beam is required. A technique for estimating the angle of incidence and the depth of focus has been devised. The main feature of the technique is to employ the specimen with a special pit, which is formed from sidewalls with an accurate tilt angle and a surface structure. In this work, the pit was formed on a (100) silicon-crystal substrate and from four (111) sidewalls with an accurate tilt angle of 54.74° and a step-like surface. The incident angle and focal depth of an electron beam was estimated by using the pit. The estimation result agreed approximately with the expected.

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Evaluation of total uncertainty in the dimension measurements using critical-dimension measurement scanning electron microscopes

Cited by 3 publications

References 5 publications

Evaluation of Errors in Feedback Control Based on Persistence Prediction in Model-Based Process Controller System for Deep Sub-100 nm Gate Fabrication

Evaluation of Errors in Feedback Control Based on Persistence Prediction in Model-Based Process Controller System for Deep Sub-100 nm Gate Fabrication

Estimation of non-statistical uncertainty in precision measurement using grey system theory

Technique for estimating the angle of incidence and depth of focus of an electron beam

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