Low Cost UV Spectrophotometer, Reflectometer, Microspectrophotometer

           Measure film thickness in seconds thanks to the microelectronics and software used by Angstrom Sun Technologies Inc. Instead of spending upwards of $50,000 on equipment that you practically need a PhD to run, you can own high quality film thickness measurement equipment that is both affordable and easy to use. There is no need to spend hours on a single measurement when results are available in seconds.

About Us

           Angstrom Sun Technologies Inc. is a privately held company, headquartered in Boston, USA. The focus of company is to provide a series of cost-effective optical solutions for characterizing thin film thickness, thick coating thickness, their optical properties (refractive index N and extinction coefficient K), surface and interface behavior, alloy concentrations and their uniformities across surface.

          Affordable, low cost, but advanced and high performance tools, including Spectroscopic Reflectometer, Microspectrophotometer, Microreflectometer, film thickness mapping system, simple desktop film thickness station and automatic variable angle spectroscopic ellipsometers, offer a way to probe film stacks nondestructively and precisely. In addition, Angstrom Sun Technologies Inc. also delivers advanced analytical services for characterizing thin films, thick coatings and complicated layer stacks.

          Angstrom Sun Technologies Inc is NOT a distributor or representative to other manufacturers for their ellipsometers, Reflectometers or Microspectrophotometers. Angstrom Sun Technologies Inc. designs and manufactures all TFProbe tools in a facility located in Boston, USA. TFProbe tools are sold and distributed by international sales networks.

          With performance and professional support as our mission, Angstrom has established a worldwide customer base since 2002, including well-known education institutions, government agencies and Fortune 500 companies, such as NASA Marshall Space Flight Center, Massachusetts Institute of Technology (MIT), Seoul National University, NanoTech Center (CESTM) at SUNY, Columbia University,  Hewlett-Packard Co., Lockheed Martin Co., General Electric (GE), Corning Inc., Bell Laboratories, Johnson-Johnson, Mylan Technologies,  EPV Solar, AVA Solar/Colorado State University, Sierra Solar Systems,  just mentioning a few here. 

Technology Development

1. Thin film (optical, semiconductor, metal and other type) materials development
2. Thin film processing technique development
3. Thin film and materials characterization technique development
4. Optical monitoring system design and implementation to various processing systems including but not limited to CVD, PECVD, PVD, CMP, e-beam deposition or ion beam sputtering system
5. Fiber optics based sensor development and instrumentation
6. Optical passive and active component design and development

About Ellipsometry, Reflectometry and Microspectrophotometry

        There are many techniques for characterizing materials, each having it’s own advantages and disadvantages and each being uniquely able to reveal material properties that other techniques can't access. Spectroscopic ellipsometry (SE) and spectroscopic reflectometry (SR) are optical techniques that are particularly flexible in that they can be used to determine the optical and physical properties of a wide variety of thin-film materials such as silicon oxide, nitride, silicon, even metal films. Their ability to do this without contact or damage to the material of interest has seen it become routinely used in R&D laboratories and within manufacturing facilities for monitoring thin film growth and deposition processes.

         In general, a reflectometer is used to acquire reflection spectrum over a wavelength range. If there is film or coating on some kind of substrate, the film or coating thickness can also be figured out from the measured reflection spectrum. Ellipsometry measurement is performed at non-normal incident angles. The two ellipsometry parameters, Psi and Del, give more information than reflectance itself. Therefore, more information can be accessible through ellipsometry technique, such as multiple layer analysis, dielectric constants calculation, surface or interface roughness, inhomogeneity behavior etc. Of course, that information is always derived from an optical model, which leads to some difficulties to use this technique although it is much more powerful than the reflectometry technique.

       Angstrom Sun Technologies Inc. manufactures both ellipsometer and reflectometer tools. Besides ellipsometer and reflectometer hardware systems, the advanced analysis software is essential to extract the desired information as above-mentioned, such as thickness, roughness, alloy concentration and dielectric constants. TFProbe 3.0 and TFProbe 2.0 software from us offer powerful analysis functions for ellipsometry and photometry with simulation and data regression. Unique but configurable mode allows different users to access different level and suitable for both R&D and production quality control purpose.

Thickness Measurement Tools

        For thickness measurement, both techniques rely on modeling. In general, ellipsometry gives better accuracy than reflectometry in thin thickness range such as below micron level. For a typical ellipsometer configuration, the maximum thickness measurable is below 10 microns. However, a reflectometer can measure up to hundreds microns of non-absorbing thick coatings.

Measurable Thickness range for Thin Films or Thick Coatings in general

       These optical methods need to have light to penetrate through film and reflect back from the film/substrate interface. Without meeting such conditions, the film thickness cannot be figured out because of lack of necessary phase information. One example is a sample with thick metal films on it. Because metal has high absorption in visible and near infrared range, light only can penetrate metal film with a depth of less than 1000 Angstroms. For such film with a thickness above 1000 Angstroms, it is impossible to measure its thickness by reflectometry or ellipsometry although reflection spectrum can be obtained with reflectometer and optical properties for metal film can be obtained with ellipsometry. Roughly, the measurable thickness for various films can be estimated from penetration depth if knowing its extinction coefficient or absorption coefficients.

Some application examples with spectroscopic ellipsometer or reflectometer measurements

• Optical constants (refractive index n and extinction coefficient k) for thin films, coatings and bulk substrate

• Dielectric constants  (real part and imaginary part) for thin films, coatings or bulk materials

• Accurate nondestructive thickness determination for multiple layer thin films or coatings

• Alloy concentration determination for various thin films such as Ge in SiGe alloy, Al in AlGaN films

• Band gap determination for GaN, SiC, AlN, AlGaN, etc.

• Porosity measurement in low-K films from modeling with EMA model (effective media approximation)

• Simultaneously determining composite film thickness and Second or third components volume fraction like Nano Au particles embedded in Y2O3 matrix

• Physical thickness and optical properties for each layer in a multiple layer stack or periodic structure such as quantum well structure

• Thickness and optical properties uniformity information through mapping site by site with advanced mapping profile setup

• Inhomogeneous film analysis in physical density or alloy concentration

• Optical properties for high-k films

• Nondestructive measurement for electrical conductivity of metal films, metallic compounds (such as WN, TiN, TaN, etc.), doped semiconductor epi layers (thickness can be also determined at the same time), other compound oxides such as ITO films

• Nondestructive measurement for doping concentration in doped semiconductors (active dopant! not total concentration as given by destructive SIMS analysis)

A Micro-spectrophotometer is used to characterize optical properties of thin films, thick coatings over a micron region area, which is typically found useful in patterned device or tiny medical device fabrications such as measuring silicone lubricant thickness on needles etc. Micro-spectrophotometer is also called micro-reflectometer, micro-reflectometer, micro-spectrometer, micro-photometer (Spectroscopic), and micro-spectroscopic photometer. With unique design by Angstrom's professionals, a user can enjoy digital imaging capability in Microspectrophotometers (MSP series) by live video, powerful digital editing, measurement tools for reflection, transmission, and absorption spectra. Data acquisition only takes milliseconds. TFProbe software allows user to set up heating stage or cooling stage for kinetic study in real time for optical property changes such as reflectance, transmittance, coating thickness, refractive index (optical constants) etc. Automatic mapping function is also available in various Microspectrophotometer models with motorized X-Y stage or Rho-Theta Stage and also motorized focus function using Joystick. Wavelength range usually is an important factor for user to consider. Angstrom's UV spectrophotometer covers from deep ultraviolet (DUV) to near-infrared (NIR) ranges. Which range should be considered will depend on several factors such as what are thickness ranges for thin film or thick coating, what is typical wavelength range of interest for reflectance or transmittance and so on.

Based on ellipsometry, reflectometry and microspectrophotometry, Angstrom Sun Technologies builds various tools from a simple, low cost film thickness measurement station (non-contact, non-destructive thickness gauge) to an advanced automatic variable angle spectroscopic ellipsometer combined with digital imaging microspectrophotometer products. In addition, a low cost desktop-style, film thickness mapping system (spectroscopic reflectometer mapping system SRM) is also available for various sample sizes. Integrated in-line solutions for film thickness /coating thickness monitoring module provide fast and easy integration even with advanced Zone-rage model for interpreting specific film properties on patterned production wafers. The probing beam size ranges from a focused micron area to a large spot with 20mm in diameter.