Mr. Eitan Zait Profile

Eitan Zait

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Publications (10)

Proceedings Article | 17 October 2008 Paper

Detection of progressive transmission loss due to haze with Galileo mask DUV transmittance mapping based on non imaging optics

Steven Labovitz, Guy Ben-Zvi, Vladimir Dmitriev, Erez Graitzer, Eitan Zait

Proceedings Volume 7122, 712216 (2008) https://doi.org/10.1117/12.801558

KEYWORDS: Photomasks, Semiconducting wafers, Deep ultraviolet, Air contamination, Pellicles, Critical dimension metrology, Quartz, Nonimaging optics, Metrology, Reticles

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In this paper, we expand on our earlier work^1,2 reporting the use of high sensitivity DUV transmission metrology as a means for detection of progressive transmission loss on mask and pellicle surfaces. We also report a use case for incoming reticle qualification based on DUV transmission uniformity. Traditional inspection systems rely on algorithms to locate discrete defects greater than a threshold size (typically > 100nm), or printing a wafer and then looking for repeating defects using wafer inspection and SEM review. These types of defect inspection do not have the ability to detect transmission degradation at the low levels where it begins to impact yield. There are numerous mechanisms for transmission degradation, including haze in its early, thin film form, electric-field induced field migration, and pellicle degradation. During the early development of haze, it behaves as a surface film which reduces 193nm transmission and requires compensation by scanner dose. The film forms in a non-uniform fashion, resulting from non-uniformity of exposure on the pattern side due to varying dose passing through the attenuating layers. As this non-uniformity evolves, there is a gradual loss of wafer critical dimension uniformity (CDU) due to a degradation of the exposure dose homogeneity. Electric-field induced migration also appears to manifest as a non-uniform transmission loss, typically presenting with a radial signature. In this paper we present evidence that a DUV transmission measurement system, Galile^TM, is capable of detecting low levels of transmission loss, prior to CDU related yield loss or the appearance of printing defects. Galileo is an advanced DUV transmission metrology system which utilizes a wide-band, incoherent light source and non-imaging optics to achieve sensitivities to transmission changes of less than 0.1%. Due to its very high SNR, it has a fast MAM time of less than 1 sec per point, measuring a full field mask in as little as 30 minutes. A flexible user interface enables users to easily define measurement recipes, threshold sensitivities, and time-based tracking of transmission degradation. The system measures through pellicle under better than class 1 clean air conditions.

Proceedings Article | 19 May 2008 Paper

Very high sensitivity mask transmittance mapping and measurements based on non imaging optics with Galileo

Guy Ben-Zvi, Vladimir Dmitriev, Erez Graitzer, Eitan Zait, Ofir Sharoni, Steven Labovitz

Proceedings Volume 7028, 702828 (2008) https://doi.org/10.1117/12.798462

KEYWORDS: Air contamination, Photomasks, Pellicles, Semiconducting wafers, Coating, Critical dimension metrology, Chromium, Deep ultraviolet, Silica, Printing

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Proceedings Article | 19 May 2008 Paper

Mask CD control (CDC) using AIMS as the CD metrology data source

Guy Ben-Zvi, Eitan Zait, Vladimir Dmitriev, Steven Labovitz, Erez Graitzer, Klaus Böhm, Robert Birkner, Thomas Scheruebl

Proceedings Volume 7028, 70281C (2008) https://doi.org/10.1117/12.793054

KEYWORDS: Photomasks, Semiconducting wafers, Critical dimension metrology, Signal attenuation, Scanners, Airborne remote sensing, Calibration, Data corrections, Cadmium, Scatterometry

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Proceedings Article | 2 May 2008 Paper

Very high sensitivity mask DUV transmittance mapping and measurements based on non-imaging optics

Guy Ben-Zvi, Vladimir Dmitriev, Erez Graitzer, Eitan Zait, Ofir Sharoni, Avi Cohen

Proceedings Volume 6792, 679213 (2008) https://doi.org/10.1117/12.798801

KEYWORDS: Photomasks, Deep ultraviolet, Imaging systems, Chromium, Nonimaging optics, Pellicles, Coating, Etching, Contamination, Air contamination

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A key feature of a photomask is the transmission (Tr) property of its many surfaces. Typical advanced 6" masks have 4 surfaces: back side Quartz (Qz), front side pattern, inside pellicle and outside pellicle. In addition to the surfaces themselves, the bulk of the transparent materials- fused silica, fluoropolymers, and MoSi shifter stacks, have specific optical Tr properties which contribute to the total Tr properties of the mask. Surface coating materials such as Cr of varying thicknesses and Anti Reflective (AR) coatings also contribute to the total Tr of the photomask. Overall the wafer printed pattern fidelity to the design depends both on the physical size of the etched lines and spaces and on the Tr properties of the spaces and of the coating material in the lines. The high MEEF values reported in advanced litho processes are most probably affected among other factors by mask Tr properties which may significantly deviate from their ideal Tr values. Factors which may contribute to transmission deviations include contamination on any of the surfaces due to haze growth, contamination by metal and oxide ions absorbed in the Qz and adsorbed on the Qz surface during mask manufacturing, photochemical degradation of the pellicle and fused silica substrates, degradation of absorber thickness (particularly MoSi) due to clean processes, and more. Accumulated contributions of all those factors can give rise to transmission variations of up to several percent. It is well known that every percent of exposure dose change may result in 1-2 nm CD change on wafer depending on exposure and process conditions. All of the above factors raise the need for an advanced transmission measurement system that will be able to measure transmission at the exposure wavelength with sensitivities better than 0.1%, preferably better than 0.01% (100 ppm). Such systems are currently not available. In this paper we describe a DUV Tr measurement system which provides the ability to measure Tr profiles of blanks and patterned masks. The system has a very fast MAM time of less than 1 sec per point and can measure the Tr Uniformity (TRU) profile of a full size mask with 100% coverage in less than 4 hours. The system is very flexible and allows the user to define the density and sensitivity of the measurements in order to suit a particular task. The system measures through pellicle under better than class 1 clean air conditions. The system is distinguishable from existing Tr measurement systems by the fact that it is non imaging, uses an incoherent wide band light source with very high SNR, high sensitivity, and very high stability.

Proceedings Article | 31 October 2007 Paper

Mask CD control (CDC) with ultrafast laser for improving mask CDU using AIMS as the CD metrology data source

Guy Ben-Zvi, Eitan Zait, Vladimir Dmitriev, Erez Graitzer, Gidi Gottlieb, Lior Leibovich, Robert Birkner, Klaus Boehm, Thomas Scheruebl

Proceedings Volume 6730, 67304X (2007) https://doi.org/10.1117/12.771190

KEYWORDS: Photomasks, Critical dimension metrology, Semiconducting wafers, Signal attenuation, Ultrafast lasers, Airborne remote sensing, Scanners, Data corrections, Control systems, Scanning electron microscopy

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Proceedings Article | 3 May 2007 Paper

The effect of intra-field CD uniformity control (CDC) on mask birefringence

Guy Ben-Zvi, Eitan Zait, Vladimir Krugliakov, Vladimir Dmitriev, Gidi Gottlieb, Sergey Oshemkov

Proceedings Volume 6533, 65330G (2007) https://doi.org/10.1117/12.736965

KEYWORDS: Photomasks, Signal attenuation, Semiconducting wafers, Birefringence, Polarization, Image processing, Critical dimension metrology, Chemical elements, Scanners, Process control

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Proceedings Article | 20 May 2006 Paper

In-field CD uniformity control by altering transmission distribution of the photomask using ultra-fast pulsed laser technology

Yasutaka Morikawa, Takanori Sutou, Yuichi Inazuki, Takashi Adachi, Yuuichi Yoshida, Kouichirou Kojima, Shiho Sasaki, Hiroshi Mohri, Naoya Hayashi, Vladimir Dmitriev, Sergey Oshemkov, Eitan Zait, Guy Ben-Zvi

Proceedings Volume 6283, 62831Y (2006) https://doi.org/10.1117/12.681762

KEYWORDS: Semiconducting wafers, Photomasks, Signal attenuation, Critical dimension metrology, Binary data, Ultrafast phenomena, Laser applications, Laser scattering, Quartz, Scattering

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Proceedings Article | 20 May 2006 Paper

Irradiation resistance of intravolume shading elements embedded in photomasks used for CD uniformity control by local intra-field transmission attenuation

Eitan Zait, Guy Ben-Zvi, Vladimir Dmitriev, Sergey Oshemkov, Rainer Pforr, Mario Hennig

Proceedings Volume 6283, 62830E (2006) https://doi.org/10.1117/12.681741

KEYWORDS: Photomasks, Critical dimension metrology, Deep ultraviolet, Semiconducting wafers, Signal attenuation, Resistance, Excimer lasers, Glasses, Manufacturing, Scanners

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Intra-field CD variation is, besides OPC errors, a main contributor to the total CD variation budget in IC manufacturing. It is caused mainly by mask CD errors. In advanced memory device manufacturing the minimum features are close to the resolution limit resulting in large mask error enhancement factors hence large intra-field CD variations. Consequently tight CD Control (CDC) of the mask features is required, which results in increasing significantly the cost of mask and hence the litho process costs. Alternatively there is a search for such techniques (1) which will allow improving the intrafield CD control for a given moderate mask and scanner imaging performance. Currently a new technique (2) has been proposed which is based on correcting the printed CD by applying shading elements generated in the substrate bulk of the mask by ultrashort pulsed laser exposure. The blank transmittance across a feature is controlled by changing the density of light scattering pixels. The technique has been demonstrated to be very successful in correcting intra-field CD variations caused by the mask and the projection system (2). A key application criterion of this technique in device manufacturing is the stability of the absorbing pixels against DUV light irradiation being applied during mask projection in scanners. This paper describes the procedures and results of such an investigation. To do it with acceptable effort a special experimental setup has been chosen allowing an evaluation within reasonable time. A 193nm excimer laser with pulse duration of 25 ns has been used for blank irradiation. Accumulated dose equivalent to 100,000 300 mm wafer exposures has been applied to Half Tone PSM mask areas with and without CDC shadowing elements. This allows the discrimination of effects appearing in treated and untreated glass regions. Several intensities have been investigated to define an acceptable threshold intensity to avoid glass compaction or generation of color centers in the glass. The impact of the irradiation on the mask transmittance of both areas has been studied by measurements of the printed CD on wafer using a wafer scanner before and after DUV irradiation.

Proceedings Article | 24 March 2006 Paper

CD variations correction by local transmission control of photomasks done with a novel laser-based process

Eitan Zait, Vladimir Dmitriev, Sergey Oshemkov, Guy Ben-Zvi, Dany Michaelis

Proceedings Volume 6152, 615225 (2006) https://doi.org/10.1117/12.656337

KEYWORDS: Photomasks, Critical dimension metrology, Inspection, Semiconducting wafers, Quartz, Deep ultraviolet, Signal attenuation, Optical components, Laser scattering, Pulsed laser operation

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As IC feature sizes become smaller and smaller, requirements for Critical Dimension (CD) variations control have become a critical issue. A new process for the control and correction of intra-field CD variations (Critical Dimension Control or CDC) was applied and it's influence on defects detection and photo-masks inspection capabilities at different modes of inspection was investigated. CD Control (CDC) of the photomask is a process in which Deep UV transmittance is selectively altered by patterns of small partially scattering shading elements (Shade in Element^Tm) inside the quartz. The shading elements are formed by a process of shooting an ultrafast laser beam focused inside the mask substrate, resulting in localized intra-volume breakdown inside the quartz which creates local pixels of modified index of refraction (delta n). An array of such pixels with constant density constitutes one shading element. Process patterns are predetermined according to a CD variations map which may be supplied from wafer CD SEM, Optical CD or mask aerial imaging simulation tool (AIMS). Thus by changing local photomask transmission levels, it is possible to correct for the CD variations inside the field. Attenuation level, or optical density of the shading elements depends on the laser pulse energy, distance between pixels, number of layers and the size of the shading element itself. Since photomask transmittance is being changed, qualification of the impact of the transmittance changes on the defect detection and analysis capabilities are required. In this study, the principles of patterning of scattering elements inside transparent media by focusing of ultra-short laser pulses were introduced and explained. Analysis of the effects to both mask and wafer due to the CDC process was verified by full printing process applied to wafers, and by aerial imaging simulation tool. More tests for CDC required also tests by automatic reticle inspection tool to be production-worthy for the 65nm node and beyond.

Proceedings Article | 20 August 2004 Paper

Photomask clear defects repair using ultrafast laser technology

Guy Ben-Zvi, Nikolay Guletsky, Vladimir Dmitriev, Sergey Oshemkov, Eitan Zait

Proceedings Volume 5446, (2004) https://doi.org/10.1117/12.557733

KEYWORDS: Photomasks, Transmittance, Optical components, Ultrafast lasers, Quartz, Laser applications, Pulsed laser operation, Laser damage threshold, Absorbance, Laser energy

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