• Journal of the Optical Society of Korea
• /
• 제17권5호
• /
• pp.392-398
• /
• 2013

As the essential techniques for the CD (Critical Dimension) measurement of the LCD pattern, there are various modules such as an optics design, auto-focus [1-4], and precise edge detection. Since the operation of image enhancement to improve the CD measurement repeatability, a ring type of the reflected lighting optics is devised. It has a simpler structure than the transmission light optics, but it delivers the same output. The edge detection is the most essential function of the CD measurements. The CD measurement is a vital inspection for LCDs [5-6] and semiconductors [7-8] to improve the production yield rate, there are numbers of techniques to measure the CD. So in this study, a new subpixel algorithm is developed through facet modeling, which complements the previous sub-pixel edge detection algorithm. Currently this CD measurement system is being used in LCD manufacturing systems for repeatability of less than 30 nm.

• Current Optics and Photonics
• /
• 제2권1호
• /
• pp.69-78
• /
• 2018

This paper presents a precise edge detection algorithm for the critical dimension (CD) measurement of a Thin-Film Transistor Liquid-Crystal Display (TFT-LCD) pattern. The sigmoid surface function is proposed to model the blurred step edge. This model can simultaneously find the position and geometry of the edge precisely. The nonlinear least squares fitting method (Levenberg-Marquardt method) is used to model the image intensity distribution into the proposed sigmoid blurred edge model. The suggested algorithm is verified by comparing the CD measurement repeatability from high-magnified blurry and noisy TFT-LCD images with those from the previous Laplacian of Gaussian (LoG) based sub-pixel edge detection algorithm and error function fitting method. The proposed fitting-based edge detection algorithm produces more precise results than the previous method. The suggested algorithm can be applied to in-line precision CD measurement for high-resolution display devices.

• 한국광학회지
• /
• 제15권1호
• /
• pp.79-85
• /
• 2004

후면의 석영면에 위상 패턴을 형성하여 투과율 조절을 구현한 포토마스크에 대해 보고한다. 위상 패턴의 크기와 패턴 조밀도에 따른 조명 동공의 형태 변화에 관한 이론적 결과와 투과율 조절 포토마스크를 사용한 웨이퍼 상 CD(critical dimension) 균일도 개선에 관한 실험적 결과에 대해 기술한다. 투과율 조절을 위한 위상 패턴은 패턴이 형성되지 않은 영역에 대해 180$^{\circ}$의 상대적 위상을 갖도록 석영면을 식각한 콘택홀 형태의 패턴을 사용하였다. 콘택홀 패턴의 크기가 작을수록 본래의 조명동공 형태를 유지하게 되며, 동일한 패턴 조밀도에서 더욱 큰 노광 광세기 저하가 일어남을 알 수 있었다. 패턴 조밀도를 위치별로 변화시켜 CD균일도 개선에 적합한 투과율 분포를 포토마스크 후면에 형성하였다. 투과율 조절 포토마스크를 140nm 디자인 롤을 갖고 있는 DRAM(Dynamic Random Access Memory)의 한 주요 레이어에 적용하여 CD 균일도를 3$\sigma$값으로 24.0nm에서 10.7nm 로 개선할 수 있었다.

• ETRI Journal
• /
• 제27권2호
• /
• pp.188-194
• /
• 2005

We report on the improvement of critical dimension (CD) linearity on a photomask by applying the concept of process proximity correction to a laser lithographic process used for the fabrication of photomasks. Rule-based laser process proximity correction (LPC) was performed using an automated optical proximity correction tool and we obtained dramatic improvement of CD linearity on a photomask. A study on model-based LPC was executed using a two-Gaussian kernel function and we extracted model parameters for the laser lithographic process by fitting the model-predicted CD linearity data with measured ones. Model-predicted bias values of isolated space (I/S), arrayed contact (A/C) and isolated contact (I/C) were in good agreement with those obtained by the nonlinear curve-fitting method used for the rule-based LPC.

• 한국광학회지
• /
• 제18권1호
• /
• pp.74-78
• /
• 2007

본 논문에서는 포토마스크 후면에 위상 패턴을 형성하여 웨이퍼 상 CD(critical dimension) 균일도를 개선할 수 있는 투과율 조절 포토마스크 기술을 ArF 리소그래피에 적용한 결과에 대하여 보고한다. 위상 패턴 조밀도에 따른 노광 광세기 변화 계산에 포토마스크 후면으로부터 포토마스크 전면까지의 광의 전파를 고려하여 ArF 파장에서의 위상 패턴 조밀도에 따른 노광 광세기 저하에 관한 실험결과를 이론적으로 재현할 수 있었다. 본 기술을 ArF 리소그래피에 적용하여 DRAM(Dynamic Random Access Memory)의 한 주요 레이어에 대해 필드 내 CD 균일도를 $3{\sigma}$ 값으로 13.8 nm에서 9.7 nm로 개선하였다.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2009년도 제37회 하계학술대회 초록집
• /
• pp.400-400
• /
• 2009

• Journal of the Optical Society of Korea
• /
• 제18권5호
• /
• pp.531-537
• /
• 2014

Through-silicon vias (TSVs) are fine, deep holes fabricated for connecting vertically stacked wafers during three-dimensional packaging of semiconductors. Measurement of the TSV geometry is very important because TSVs that are not manufactured as designed can cause many problems, and measuring the critical dimension (CD) of TSVs becomes more and more important, along with depth measurement. Applying white-light scanning interferometry to TSV measurement, especially the bottom CD measurement, is difficult due to the attenuation of light around the edge of the bottom of the hole when using a low numerical aperture. In this paper we propose and demonstrate four bottom CD measurement methods for TSVs: the cross section method, profile analysis method, tomographic image analysis method, and the two-dimensional Gaussian fitting method. To verify and demonstrate these methods, a practical TSV sample with a high aspect ratio of 11.2 is prepared and tested. The results from the proposed measurement methods using white-light scanning interferometry are compared to results from scanning electron microscope (SEM) measurements. The accuracy is highest for the cross section method, with an error of 3.5%, while a relative repeatability of 3.2% is achieved by the two-dimensional Gaussian fitting method.

• 한국전기전자재료학회논문지
• /
• 제16권6호
• /
• pp.515-521
• /
• 2003

There are now many theoretical investigations and real manufactures for numerous applications of photonic crystals (PCs) associated with photonic band gap and photonic integrated circuits. However, there are some difficulties to design and fabricate the desired pattern quality. It is not easy to satisfy accurate critical dimension (CD) for patterns with arbitrary shapes and pitch sizes aligned in various directions. In this work, we report the optimum conditions to better fabricate and design, and greatly improve pattern quality in delineating two-dimensional (2D) PCs in the nanometer range using single- step e-beam lithography system with conventional exposure mode.

• Journal of the Optical Society of Korea
• /
• 제6권4호
• /
• pp.180-184
• /
• 2002

In this study, we investigated mask errors, photo errors with attenuated phase shift mask and off-axis illumination, and etch errors in dry etch conditions. We propose that total process proximity correction (TPPC), a concept merging every process step error correction, is essential in a lithography process when minimum critical dimension (CD) is smaller than the wavelength of radiation. A correction rule table was experimentally obtained applying TPPC concept. Process capability of controlling gate CD in DRAM fabrication should be improved by this method.

• Transactions on Electrical and Electronic Materials
• /
• 제15권3호
• /
• pp.159-163
• /
• 2014

More accurate CD (Critical Dimension) control is required for the nanometer-scaled devices. However, since the reflectivity between substrate and PR (Photoresist) becomes higher, the CD (Critical Dimension) swing curve was intensified. The higher reflectivity also causes PR notching due to the pattern of sub-layer. For this device requirement, it was optimized for the thickness, refractive index(n) and absorption coefficient(k) in the bottom anti-reflective coating(BARC; SiON) and photoresist with the minimum reflectivity. The computational simulated conditions, which were determined with the thickness of 33 nm, n of 1.89 and k of 0.369 as the optimum condition, were successfully applied to the experiments with no standing wave for the 0.13um-device. At this condition, the lowest reflectivity was 0.44%. This optimum condition for BARC SiON film was applied to the process for 0.13um-device. The optimum SiON film as BARC to PR and sub-layer could be formed with the accurate CD control and no standing waver for the nanometer-scaled semiconductor manufacturing process.