Zeta^™-20 Optical Profiler

The Zeta^™-20 is a fully integrated optical profiling microscope that provides 3D metrology and imaging capability in a compact, robust package. The system is powered by ZDot^™ technology, which simultaneously collects high-resolution 3D data and a True Color infinite focus image. The Zeta-20 3D microscope supports both R&D and production environments with Multi-Mode optics, easy-to-use software, and a low cost of ownership. The Zeta-20HR configuration is designed to address advanced solar cell metrology requirements.

Product Description

The Zeta-20 benchtop optical profiler is a non-contact, 3D microscope and surface topography measurement system. The 3D optical profiling system is powered by patented ZDot technology and Multi-Mode optics, enabling measurement of a variety of samples: transparent and opaque, low to high reflectance, smooth to rough texture, and step heights from nanometers to millimeters.

The Zeta-20 3D optical profiling system integrates six different optical metrology technologies in one configurable and easy-to-use system. ZDot measurement mode simultaneously collects a high-resolution 3D scan and a True Color infinite focus image. Other 3D measurement techniques include white light interferometry, Nomarski interference contrast microscopy, and shearing interferometry. Film thickness can be measured with ZDot or an integrated broadband reflectometer. The Zeta-20 is also a high-end microscope that can be used for sample review or automated defect inspection. The Zeta-20 3D optical profiling microscope supports both R&D and production environments by providing comprehensive step height, roughness, and film thickness measurements, and defect inspection capability.

Features

Easy to use optical profiler with ZDot and Multi-Mode optics to address a wide range of applications
High-quality microscope for sample review or defect inspection
ZDot: Simultaneously collects a high-resolution 3D scan and a True Color infinite focus image
ZXI: White light interferometry for wide area measurements with high z resolution
ZIC: Interference contrast for quantitative 3D data of surfaces with sub-nanometer roughness
ZSI: Shearing interferometry for images with high z resolution
ZFT: Film thickness and reflectance is measured with an integrated broadband reflectometer
AOI: Automatic optical inspection to quantify defects on the sample
Production capability: Fully automated measurements with sequencing and pattern recognition

Applications

Step height: 3D step height from nanometers to millimeters
Texture: 3D roughness and waviness on smooth to very rough surfaces
Form: 3D bow and shape
Stress: 2D thin film stress
Film thickness: transparent film thickness from 30nm to 100µm
Defect inspection: capture defects greater than 1µm
Defect review: KLARF files are used to navigate to defects to measure 3D surface topography or scribe defect locations

Industries

Solar: photovoltaic solar cells
Semiconductor and compound semiconductor
Semiconductor WLCSP (wafer-level chip scale packaging)
Semiconductor FOWLP (fan-out wafer-level packaging)
PCB (printed circuit board) and flexible PCB
MEMS: Micro-electro-mechanical systems
Medical devices and microfluidic devices
Data storage
Universities, research labs and institutes
And more: Contact us with your requirements

Step Height

The Zeta-20 optical profiler is capable of measuring 3D, non-contact step heights from nanometers to millimeters. ZDot and Multi-Mode optics provide a range of methods to measure the step height. ZDot is the primary measurement technique and can quickly measure steps from tens of nanometers to millimeters. ZXI interferometry can be used to measure steps from nanometers to millimeters over a large area. ZSI shearing interferometry can be used to measure steps less than 80nm.

Film Thickness

The Zeta-20 optical profiler is capable of measuring film thickness of transparent film(s) using ZDot or ZFT measurement techniques. ZDot is used to measure transparent films greater than 10µm, such as photoresist or microfluidic device layers that are coated on higher refractive index substrates. ZFT uses an integrated broadband reflectometer to measure films from 30nm to 100µm. This can be done for a single or multiple-layer film stack, with the user entering the properties of the film or using a model to fit the spectrum.

Texture: Roughness and Waviness

The Zeta-20 3D optical microscope measures 3D texture, quantifying the sample’s roughness and waviness. ZDot enables measurement of roughness ranging from tens of nanometers to very rough surfaces. ZSI and interferometry enable measurement of smooth surfaces, from angstroms to microns. Software filters separate the measurements into roughness and waviness components and calculate parameters, such as root mean square (RMS) roughness. Nomarski interference contrast microscopy enables visualizing very fine surface detail by revealing small changes in the slope.

Form: Bow and Shape

The Zeta-20 surface microscope can measure the 2D and 3D shape or bow of a surface. This includes measurement of wafer bow that can result from mismatch between layers during the production of semiconductor or compound semiconductor devices. The Zeta-20 can also quantify the 3D height and radius of curvature of structures, such as a lens.

Stress: Thin Film Stress

The Zeta-20 is capable of measuring stress induced during the manufacture of devices with multiple layers, such as semiconductor or compound semiconductor devices. The bow of the surface is accurately measured using a stress chuck to support the sample in a neutral position. The change in shape from a process, such as film deposition, is then used to calculate the stress, applying the principles of Stoney’s equation. The Zeta-20 measures 2D stress by finding the height of the sample surface at user-defined intervals across the full sample diameter and then combining the data into a profile of the sample shape.

Automated Defect Inspection

The Zeta-20 optical microscope is capable of Automated Optical Inspection (AOI) to rapidly inspect the sample, differentiate different defect types, and map defect density across the sample. When combined with the 3D metrology capability, the Zeta-20 can provide additional information about the defect that cannot be obtained with 2D inspection systems, enabling quicker identification of the defect source.

Defect Review

Zeta-20 defect review uses an inspection tool KLARF file to drive the stage to the defect locations. The user can inspect the defect with the high-quality microscope or measure the topography of the defect, such as the height, thickness, or texture. This provides additional detail about the defect that cannot be obtained from a 2D defect inspection system. The Zeta-20 can also mark defects with a scribe, making it easier to find the defect on tools, such as SEM review tools, that have a limited field of view.

Photovoltaic Solar Cells

The Zeta-20 optical profiler is well-suited for solar cell applications by supporting measurement of surfaces that combine very low and very high reflectance materials. The system can quantify the post-etch texture – pyramid structures that reflect less than 1% of the incident light and are critical to the light capture ability of the solar cell. Adjacent to the texture are silver paste contact lines that have a reflectance greater than 90%. The Zeta-20 with ZDot and a high measurement dynamic range can simultaneously measure the very low and very high reflectance regions, quantifying the silver paste line height, width, and volume of silver deposited that determines electrical line resistance. In addition, the Zeta-20 is used for measurement of the incoming wafer roughness, nitride film thickness using ZFT, isolation trench depth, sample bow, stress, and 3D defects. Learn More

Semiconductor and Compound Semiconductor Packaging

The Zeta-20 optical profiling system supports wafer-level chip scale packaging (WLCSP) and fan-out wafer-level packaging (FOWLP) metrology requirements. A key enabling technology is the capability to measure the height of the plated copper with the dry photoresist film intact. This is accomplished by measuring through the transparent photoresist to the seed layer to measure the height of the copper pillar, thickness of the photoresist, and relative height difference of copper and photoresist. Additional applications include measurement of redistribution lines (RDL), under bump metallization (UBM) height and texture, photoresist opening critical dimension (CD), photoresist thickness, and polyimide thickness. Coplanarity of the metal contacts can also be measured to determine if the bump height meets final device packaging connectivity requirements.

Printed Circuit Board (PCB) and Flexible PCB

The Zeta-20’s high dynamic range enables surface roughness and step height measurements from nanometers to millimeters without a configuration change. It can handle high-reflectance films (e.g., copper) as well as transparent films that are commonly found on PCBs. The Zeta-20 supports critical dimension measurements (height and width) for blind via holes, line traces and hot bars, plus surface roughness.

Laser Ablation

The Zeta-20 can measure topography changes induced by laser surface processing for semiconductors, LED, microfluidic devices, PCBs, and more. Lasers have been adopted for precision micro-scale machining and surface conditioning in industries, such as semiconductors, LED, and biomedical devices. For the semiconductor industry, measurement of the height and width of a wafer ID mark is critical to ensuring it can be read successfully throughout numerous processing steps. The Zeta-20 can measure the step height of high aspect ratio via holes created on flexible circuits and wafers. It can also measure the depth and width of the solar cell isolation trench that improves device efficiency.

Microfluidics

The Zeta-20 has the capability to measure microfluidic devices fabricated in materials, such as silicon, glass, and polymers. The system quantifies the height, width, edge profile, and texture of channels, wells, and control structures. The Zeta-20 can also measure the final device after it is sealed with a transparent top cover plate – compensating for the change in refractive index and quantifying changes from the stress of applying the cover plate.

Biotechnology

The Zeta-20 is well-suited for biotechnology applications, offering non-contact measurement of a variety of sample surfaces having features from nanometers to millimeters. The Zeta-20 can measure high aspect ratio steps, such as the depth of deep wells for biotech devices. Micro-needle array structures for drug delivery can be measured taking advantage of the high numerical aperture objective lens and the ability to resolve a very low reflectance sample.

Data Storage

The Zeta-20 CM is dedicated to measuring magnetic disk edge geometry and inspecting for contamination or damage. At the edge of the disk, the transition between the top surface and side wall must have a smooth chamfer profile, otherwise the disk edge turbulence may cause the read-write head to suffer a fatal crash on the disk. This system configuration includes a tilt stage to rotate the disk during edge measurement and inspection.

The options for the Zeta^™-20 Optical Profiler are available to add on with your new product, or in the future. Contact your sales rep to learn more.

New Zeta-20HR

New! The Zeta-20HR high resolution configuration extends the capabilities of the Zeta-20 optical profilometer with an enhanced design optimized for solar cell metrology applications, including a 230mm x 230mm stage and advanced solar texture analysis.

Learn More

ZFT: Zeta Film Thickness

The Zeta-20 offers an integrated broadband spectrometer for transparent thin film thickness measurements from 30nm to 100µm. It is capable of measuring single layer or multi-layer stack film thickness with the user selecting the refractive index values from the library of materials. The film thickness can be mapped across the sample to determine the sample uniformity.

ZFT works on some of the least reflective surfaces, such as solar cells with reflectance of less than 0.1%. Many film thickness tools have difficulty obtaining a signal from these type of surfaces, since they depend on specular reflected light to calculate phase change or other parameters. The broadband white light and normal incidence illumination allow the tool to be used for a variety of optically transparent films with low reflectance.

ZXI: Zeta Vertical-Scanning Interferometry

The Zeta-20 supports phase scanning interferometry (PSI) and vertical scanning interferometry (VSI) when combined with the piezo stage and an interferometric objective lens. PSI enables fast measurements of step heights from angstroms to hundreds of nanometers. VSI enables measurement of step heights from hundreds of nanometers to hundreds of microns. Both are performed at better than nanometer-level resolution, independent of the objective numerical aperture.

ZIC: Zeta Interference Contrast

The Zeta-20 utilizes Nomarski differential interference contrast microscopy to provide enhanced imaging of fine surface detail. Nomarski microscopy uses polarization and a prism to change the phase to enhance changes in slope on the sample surface. This enables visualization of defects on super-smooth surfaces, such as a monolayer of a contaminant. The ZIC scanning mode can convert these images into quantitative measurements of sub-nanometer level roughness by correlating the change in slope with roughness measured by another technique.

ZSI: Zeta Shearing Interferometer

The Zeta-20 shearing interferometer measurement technique (ZSI) enhances the ZIC measurement by adding a change in the phase. Multiple images are collected with different phases, then processed through advanced algorithms to generate a quantitative measure of surface topography with angstrom-level resolution. This technique does not require interferometric objectives and has no Z-stage scanning, resulting in high-resolution measurements from angstroms to 80nm.

Objective Lenses

A broad range of objective lenses are available including 1.25x – 150x normal objectives, long working distance objectives, ultra-long working distance objectives, refractive index corrected objectives, through transmissive objectives, liquid immersion objectives, and vertical scanning interferometry objectives.

Couplers

The Zeta-20 can be configured with four different optical couplers to change the optics magnification. The system can be configured with the 1x coupler to keep the native magnification, or configured with 0.35x, 0.5x, or 0.63x couplers to increase the magnification.

Objective Lens Turret

The Zeta-20 can be configured with a 5 or 6 position manual turret and an objective lens sensor for automatic objective identification. The system can also be configured with a 6 position motorized turret for fully automated operation.

Sample Lighting

The Zeta-20 uses dual high-brightness white LEDs as standard lighting. Backlighting through the sample chuck is also available to enhance the light for challenging transparent samples. The Zeta-20 also supports darkfield lighting from the side.

Stages

The Zeta-20 can be configured with a variety of stages to enhance system performance. A piezo Z-axis stage can be added to improve Z resolution for measurement of nanometer-level step heights with the ZDot or ZXI measurement modes. The Z-stage can be mounted on a swivel to enable rotating the head about the sample to change the angle of incidence on the surface. The XY stage can be configured with manual 100 or 300mm travel or motorized 150 or 200mm travel. A manual rotary stage can be added to the XY stage. A manual tip and tilt stage can be added to level the stage for interferometry measurements.

Sample Chucks

The Zeta-20 has a range of chucks available to support application requirements. Solar samples require a 156mm sample chuck or a solar tilt edge chuck to tilt the sample to measure the edge. Backlight chucks are available for transparent substrates to support transmitted illumination. A 300mm wafer chuck is available. If we do not have the chuck you need, please contact KLA with your requirements.

Isolation Tables

The Zeta-20 has passive isolation feet built into the base of the system. If additional isolation is required, passive and active benchtop isolation tables are available.

Step Height and Film Thickness Standards

The Zeta-20 uses thin and thick film NIST traceable step height standards offered by VLSI Standards. The standards feature an etched quartz step with a chrome coating. A step height range of 8nm to 250µm is available.

An available certified multi-step standard has nominal step heights of 8, 25, 50, and 100µm. The standard has various pitch patterns for XY calibration. A certified film thickness standard is available for ZFT that includes a reference silicon surface and a nominal 270nm silicon dioxide film thickness. Reference roughness and mirror samples are also available.

Automated Sequencing Software

Automated sequencing software utilizes the motorized XY stage to allow the user to program measurement locations on the sample. The system will automatically measure each site and save the results in user-defined folders. An output report with sample statistics is generated to summarize the results.

Advanced sequencing software includes pattern recognition to automatically align the sample. This enables fully automated measurements, reducing the impact of operator error. Auto calibration can also be enabled when using embedded standards on the stage.

Stitching Software

Automated image stitching software utilizes the motorized XY stage to combine adjacent scans to generate a stitched data set that is larger than a single field of view. The system automatically measures every site, aligns the images, and combines them into one data set. The results can be analyzed like any other results file.

Apex Analysis Software

Apex analysis software enhances the tool’s standard data analysis capability with an extended suite of leveling, filtering, step height, roughness, and surface topography analysis techniques. Apex supports ISO roughness calculation methods plus local standards, such as ASME. Apex also serves as a report writing platform with the capability to add text, annotations, and pass/fail criteria. Apex is offered in eleven languages.

Offline Analysis Software

The Zeta-20 offline software has the same data analysis and recipe creation capability that exists on the tool. This enables the user to create recipes and analyze data without using valuable tool time.

A Scientist’s Guide to Candy Selection

The KLA Instruments Zeta-20 was used to map and compare the surface topography of Halloween candy favorites, including M&Ms, Bit-O-Honey, Reese’s peanut butter cups, Heath Bars, Jolly Ranchers, Skittles, Snickers, SweeTarts, Kit Kat bars, Lemonheads, candy corn, and bubblegum. Yum!

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Measurement of Deep Trenches to Study the RIE Lag Effect

The Zeta-20 optical profiler provides a quick, non-destructive method for measuring the profile and depth of high aspect ratio trenches to characterize the lag effect of reactive ion etching (RIE).

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Characterization of HEMT Vias

The Zeta-Series optical profilers provide accurate measurement and automated analysis of high aspect ratio structures such as HEMT vias using non-destructive and high throughput metrology techniques.

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ZDot^™ Technology

The Zeta^™ optical profilometer has the advantage of providing uniform lateral resolution without contacting potentially delicate surface features. KLA Instruments’ proprietary ZDot^™ technology utilizes a structured illumination technique to enhance the vertical resolution of the objective lens of the Zeta optical microscopes. This application note discusses ZDot technology and its usage and applications.

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How Do You Optimise Your Laser Settings for Precise Micro Manufacturing

Author: Dr. Diane Hickey-Davis
Publication: Commercial Micro Manufacturing International Vol 9 No.3

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Measuring Sealed Micro Fluidic Devices

Author: Dr. Diane Hickey-Davis, Dr. Ian Holton
Publication: Commercial Micro Manufacturing International Vol 9 No.1

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Recent Major Advances In 3D Optical Profiling of Micro Surfaces

Author: Dr. Ian Holton
Publication: Commercial Micro Manufacturing International Vol 6 No.1

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Texture Process Monitoring in Solar Cell Manufacturing Using Optical

Author: Vamsi Velidandla, et. al.
Publication: 37th IEEE Photovoltaic Specialists Conference (2011)

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Measurements with 3D non-contact optical profilometry

Author: Nelluri Srinivas, et. al.
Publication: South Asian Journal of Engineering and Technology Vol.1, No.1 (2015) 41–45

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Automated Process Metrology in Solar Cell Manufacturing

Author: Vamsi Velidandla, et. al.
Publication: 37th IEEE Photovoltaic Specialists Conference (2011)

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Closed Channel Optical Metrology for Microfluidics Applications

The Zeta-20 optical profiler with ZDot^™ technology was used to measure open channel and closed channel microfluidics devices, including step height and surface roughness inside the channel.

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3D Surface Roughness Characterization

Zeta^™ 3D optical profilers are used to measure surface roughness of N95 face masks, sapphire wafers for LED devices, and porous chucks. An overview of Zeta measurement technology is also included.

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Objective Lens Selection

The KLA Instruments optical profilers utilize a number of different objective lenses, depending on the system configuration and the application. This application note discusses different objective types and the various factors affecting magnification and resolution.

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Zeta™-20 Optical Profiler

Zeta™-20 Optical Profiler

Product Description

Features

Applications

Industries

Step Height

Film Thickness

Texture: Roughness and Waviness

Form: Bow and Shape

Stress: Thin Film Stress

Automated Defect Inspection

Defect Review

Photovoltaic Solar Cells

Semiconductor and Compound Semiconductor Packaging

Printed Circuit Board (PCB) and Flexible PCB

Laser Ablation

Microfluidics

Biotechnology

Data Storage

New Zeta-20HR

ZFT: Zeta Film Thickness

ZXI: Zeta Vertical-Scanning Interferometry

ZIC: Zeta Interference Contrast

ZSI: Zeta Shearing Interferometer

Objective Lenses

Couplers

Objective Lens Turret

Sample Lighting

Stages

Sample Chucks

Isolation Tables

Step Height and Film Thickness Standards

Automated Sequencing Software

Stitching Software

Apex Analysis Software

Offline Analysis Software

A Scientist’s Guide to Candy Selection

Measurement of Deep Trenches to Study the RIE Lag Effect

Characterization of HEMT Vias

ZDot™ Technology

How Do You Optimise Your Laser Settings for Precise Micro Manufacturing

Measuring Sealed Micro Fluidic Devices

Recent Major Advances In 3D Optical Profiling of Micro Surfaces

Texture Process Monitoring in Solar Cell Manufacturing Using Optical

Measurements with 3D non-contact optical profilometry

Automated Process Metrology in Solar Cell Manufacturing

Closed Channel Optical Metrology for Microfluidics Applications

3D Surface Roughness Characterization

Objective Lens Selection

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