ZEISS Spectroscopy
Employee in the clean room holds wafers in his hands
OEM Applications

Semiconductor

  • Critical dimension measurement
  • Thin film measurement / ellipsometry
  • Plasma monitoring & endpoint detection
  • Wet process control

Pushing critical dimensions to their limits Critical dimension & overlay

The continuous shrinkage of the Critical Dimension (CD) in semiconductor devices and the rapid development towards more complex 3D structures continues to push lithography and etch tools to their limits. To ensure high yields, a tight control of the patterning process in front-end manufacturing is needed, requiring optical metrology tools for CD variation and pattern placement errors (overlay) beyond the resolution limit of classical optical metrology.

Challenges in thin film and layer stack metrology Thin film measurement / ellipsometry

As the semiconductor industry continues to follow Moore’s law, thin film thickness is one of the most rapidly changing dimensions. The reduction in thickness of films, which goes into the sub-nanometer range, presents a challenge for current manufacturing metrology.

Achieving atomic precision Plasma monitoring & endpoint detection

Plasma etching and deposition are widely used techniques in semiconductor manufacturing. As pattern sizes decrease and gain complexity, the need for precise and fast in-situ process monitoring becomes more important. Real-time control of plasma process parameters are required, especially for etching endpoint detection, plasma control and chamber cleaning.

Tracking multi-constituent chemical bath conditions Wet process control

The success of wet cleaning & etching processes in semiconductor manufacturing is mainly defined by the cost of chemicals, cycle times and wafer yield. Within wet processes, maintaining optimal chemical bath conditions is crucial. Challenges include the use of multi-constituent cleaners, concentration variability due to process loadings, solvent drag-out or tank replenishment. These all require precise, in-line process control metrology.

Our solutions

FinFET transistors for 14nm, 10nm, 7 nm, 5nm technology node of chip manufacturing process. 3D models compare the size and area. Illustration for Moore's law and semiconductor transistor roadmap.

Critical dimension & overlay measurement

Optical scatterometry or optical critical dimension (OCD) is a common in-line metrology method for process control in semiconductor production. In addition to imaging techniques such as CD-SEM, OCD has developed as a fast, precise and non-destructive metrology, giving information about CD, height or side wall angles of the observed pattern structures. The relevant profile shape parameters are determined by illuminating a small area on the wafer under a certain angle and observing the scattered light via a spectrometer within the UV-NIR spectral range. To determine pattern profile information, model-based machine learning techniques are applied to wafer training spectra as a reference. ZEISS supplies OEM high-performance spectrometers like the MCS-CCD (190 - 980 nm) or custom configurations for CD and overlay OCD-metrology.
High end optical 
plane gratings enable you to measure cutting edge parameters in your metrology and are designed to specific customer requirements, such as the lowest levels of stray light, high efficiency and lowest wavefront aberration.

Ellipsometer tool in a laboratory. Silicon wafer of purple color measure thickness of film on ellipsometer

Thin film measurement / ellipsometry

Within semiconductor front-end manufacturing processes such as etching, deposition or cleaning, the thickness of thin films and complex layer stacks must be measured. Spectroscopic ellipsometry (SE) and spectral reflectometry (SR) allow for the in-line, non-contact measurement of optical thickness ranging from a few nm to several tens of microns. SE is is based on the change in the polarization state of light as it is reflected obliquely from a thin film probe. It utilizes a model-based approach to determine film thickness, surface & interface roughness as well as various optical/material properties. In addition to SE, normal-incidence spectral reflectometry (SR) is a well established inspection method for fast characterisation of thin film thickness. ZEISS MCS series (190 - 1015 nm) and CGS series (190 - 1100 nm) spectrometers have unmatched SNR, high UV-sensitivity, minimized stray light and high-volume supply. We support the custom design and manufacture of specific spectrometers with numerous plane gratings and mono- & polychromator gratings. ZEISS gratings provide high dynamic range in the spectrometers due to the lowest levels of stray light.

MCS spectrometer module next to plasma chamber in clean room

Plasma monitoring & endpoint detection

The production of semiconductor devices relies heavily on plasma etching processes. When patterns are etched on a wafer, the in-line control of etching progress is vital to avoid over and under-etch and ensure optimized process parameters, high yield and productivity. Optical metrology, such as optical emission spectroscopy (OES), spectral reflectometry (SR) and laser interferometry are common for plasma etch endpoint control. ZEISS MCS-CCD (190 - 1015 nm) and CGS series (190 - 1100 nm) is ideal for optical emission spectroscopy where concentrations of plasma reactants are monitored during etching in real-time. MCS-CCD feature high resolution, broad spectral coverage, good wavelength accuracy and fast readout. For spectral reflectometry the spectrometers of the MCS series and CGS series provide the required high dynamic range and good signal-to-noise ratio. ZEISS offers plane gratings, which are used in single or multichannel spectrometers from VUV to NIR for customer-specific spectrometer developments for plasma monitoring and endpoint detection. Plane gratings with a wide range of line densities between 30 l/mm and 3600 l/mm provide well adapted resolution and signal-to-noise ratios due to the lowest levels of stray light.

Close-up view of a modern GPU card with circuit

Wet process control

The monitoring of heated chemical baths in semiconductor wet processes requires tight control of chemical mixtures. Constant bath conditions have to be maintained during production to insure uniform process stability. Compared to standard conductivity analyzers, fiber-coupled NIR spectrometers enable remote placement and multi-constituent analysis, preventing costly yield losses due to suboptimal chemistry. ZEISS PGS NIR (960 - 2200 nm) offer a broad choice of NIR analyzers for the real-time, multi-point concentration monitoring of chemicals such as SC1, SC2, SPM, BOE or DHF. PGS NIR spectrometers have a small footprint, robust design, high SNR ratio and fast readout.

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