Alignment Mark Optimization to Reduce Tool- and Wafer-Induced Shift for XRA-1000

Ina, Hideki; Sentoku, Koichi; Matsumoto, Takeru; Sumitani, Hiroaki; Suita, Muneyoshi

doi:10.1143/jjap.38.7065

Cited by 7 publications

(3 citation statements)

References 2 publications

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“…(1) Hardware such as optical detected system, mark design. 19,20) (2) Software such as signal processing. 21) (3) Other metrology tool which deals with the inspection data.…”

Section: Considerationmentioning

confidence: 99%

Signal Processing Using Karhunen–Loève Expansion for Wafer Focus Measurement in Lithography

Oishi

Ina

Miyashita

2011

Jpn. J. Appl. Phys.

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We propose a new signal processing method using Karhunen–Loève (KL) expansion for wafer focus measurement in lithography. With the improvement in the critical dimension (CD) accuracy, more high accuracy of wafer focus measurement becomes to be necessary. Recently, it is said that focus accuracy should be required within several ten nanometers. The accuracy of the focus measurement of the actual process wafer does not meet the requirement values due to the complexity of its structure. The objective of this study is the improvement of the focus accuracy for the actual process wafers. Our proposing focus signal processing has two steps. The first step is a supervised learning step in which main component signal waveforms (basis functions) are obtained by using KL expansion from many focus signals whose center positions are known in advance. The second step is a center position detecting step in which an input signal is approximated by using the basis functions obtained in the learning step and the center position of the signal is detected. From a comparison between the conventional signal processing and the proposing signal processing, we obtained the following result to simulated signal. Focus accuracy was rapidly improved (97%) when three basis functions were used for the approximation. By using this technology, the focus detection system can be achieved with a high accuracy and robust against various process wafers.

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“…(1) Hardware such as optical detected system, mark design. 19,20) (2) Software such as signal processing. 21) (3) Other metrology tool which deals with the inspection data.…”

Section: Considerationmentioning

confidence: 99%

Signal Processing Using Karhunen–Loève Expansion for Wafer Focus Measurement in Lithography

Oishi

Ina

Miyashita

2011

Jpn. J. Appl. Phys.

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“…Therefore, an accurate position measurement technique is required for alignment during contact. 7 Therefore, we believe that a direct observation of the gratings is better than superimposition and will produce a better alignment accuracy. 4 In today's semiconductor lithography, the wafer-induced shift ͑WIS͒, 5,6 which is caused by a resist ͑resin in the case of imprint͒ covering the patterned substrate, leads to alignment errors in some cases.…”

Section: Introductionmentioning

confidence: 99%

Position measurement method for alignment in UV imprint using a high index mold and “electronic” moiré technique

Suehira

Terasaki

Okushima

et al. 2007

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

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In UV imprint, positioning errors can occur between a mold and a wafer due to pressure when there is a contact with the UV resin. The moiré technique, which is produced by superimposition of two gratings, is a well-known and simple method for high-resolution position measurement. However, the authors believe that a direct observation of two separate gratings is more appropriate for higher positioning accuracy. Here they propose a new method for the position measurement, which obtains "electronic" moiré fringes by combining the images of two separate gratings from different areas of the mold and the wafer. The fundamental detection error was = 0.15 nm. The repeatabilities of the total system was = 0.68 nm in air and = 0.73 nm in resin. The linearity of the measurement value to control signal was R 2 = 0.97.

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“…Endeavors in wafer alignment can be broadly classified as efforts to ͑a͒ improve wafer placement and holding, 1-3 ͑b͒ study alignment error sources, [4][5][6] and ͑c͒ monitor the wafer position. [7][8][9][10] Techniques reported thus far for wafer position monitoring include the use of ͑i͒ imaging of marks with a CCD camera, 7 ͑ii͒ imaging of marks with a series of photosensors, 8 ͑iii͒ sensing of diffracted light from marks, 5,9 and ͑iv͒ observation of moiré patterns. 10 These techniques are predisposed primarily to sense lateral misalignment of the wafer.…”

Section: Introductionmentioning

confidence: 99%

Simple tilt and height location monitoring of wafers

Tay

Ong

2006

Opt. Eng

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Good alignment is needed in various wafer processes. Reflectometry is a well-established technique that continues to be widely used to monitor the thickness of wafer thin films. The use of a reflectometer was investigated to detect incorrect tilt and height of wafer placement. We found that it could be used in the spectroscopic or the monochromatic mode and provided results whether the wafer was bare or coated. We also found that the technique was somewhat more sensitive to tilt of bare wafers, and more sensitive to height displacements of coated wafers.

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Alignment Mark Optimization to Reduce Tool- and Wafer-Induced Shift for XRA-1000

Cited by 7 publications

References 2 publications

Signal Processing Using Karhunen–Loève Expansion for Wafer Focus Measurement in Lithography

Signal Processing Using Karhunen–Loève Expansion for Wafer Focus Measurement in Lithography

Position measurement method for alignment in UV imprint using a high index mold and “electronic” moiré technique

Simple tilt and height location monitoring of wafers

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