ZFT: Zeta Film Thickness

The Zeta-388 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 samples 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-388 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-388 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-388 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-388 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-388 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-388 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, such as patterned sapphire substrates (PSS). The Zeta-388 also supports darkfield lighting from the side.

Stages

The Zeta-388 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 XY stage is motorized and can be configured with standard chuck, bowed wafer chuck, or backside illumination chuck.

Sample Chucks

The Zeta-388 has a range of chucks available to support application requirements for samples from 50 to 200mm, including chucks to support bowed wafers. Backlight chucks are available for transparent substrates to support transmitted illumination, required for patterned sapphire substrates. If we do not have the chuck you need, please contact KLA with your requirements.

Isolation Tables

The Zeta-388 has passive isolation built into the base of the system. For applications requiring better isolation, an active isolation table is available. The Zeta-388 has a standard acoustic enclosure to isolate the system from environmental noise, and to protect the user from sample handler motion.

Step Height and Film Thickness Standards

The Zeta-388 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-388 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.