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Thin Film Spectra Experiment
Conducted by: David Ademe, Avantes Inc.
Theme: Thin film Measurement
Background/Applications:
Thin films play a vital role in a variety of industries and applications, such as consumer electronics, semiconductors and optics. Thin film deposition refers to the process of applying a very thin film of material, typically between a few nanometers to 100 micrometers, onto a substrate surface to be coated, or onto a previously deposited coating to form layers. Therefore, it is critical to monitor and control this coating process. This monitoring is achieved through measuring the substrate surface characteristics and thickness of the film. As these thicknesses need to meet strict and specific conditions, spectroscopy is often used to measure and control this thickness.
Similar to thin film coatings are parylene coatings. Parylene coatings are ultra-thin and uniform coatings that provide a number of high-value surface treatment properties such as moisture, chemical and dielectric properties, and thermal and UV stability. These properties make parylene coatings an ideal choice for a number of applications throughout the medical device, electronics, transportation and aerospace industries. One of the more common types of parylene is Parylene C, which is produced from the same material as Parylene N, modified only by the substitution of a chlorine atom for one of the aromatic hydrogens. Parylene C has a useful combination of electrical and physical properties, plus a very low permeability to moisture and corrosive gases.
Our objective with this experiment is to measure the thickness of several thin film and parylene coated samples, demonstrating the effectiveness and usefulness of Avantes equipment in these vital industries.
Description of System:
The setup for this experiment incorporates the new Reflectometer system from Avantes. The reflectometer is an easy to use package that incorporates a halogen light source, a reflection probe and the AvaSpec-Mini to perform reflection, thin film and parylene measurements.
The new generation, our AvaSpec-Mini MK-II series (AvaSpec-Mini2048CL and AvaSpec-Mini4096CL) is definitely one of the smallest types of spectrometers on the market today. In cases where size matters, the AvaSpec CompactLine family offers spectrometers with the smallest form factor. This enables easier integration of our spectrometers into machines and handheld devices. Squeezing down the size hardly compromises the performance of the instruments, but limits the customer a bit in the number of possible configurations. Customization is possible when adequate volumes are needed. This makes the CompactLine especially suited for OEM users wanting to integrate a spectrometer into their own devices. The AvaSpec-Mini-CL series can be equipped with a 2048 pixel CMOS detector or our first-to-the-market 4096-pixel array. Enjoy the speed and enhanced native UV/NIR response of CMOS with an incredible resolution of up to 0.09 nm unavailable anywhere else. The low stray light design allows stray light levels from as low as 0.2% and the fast response time boasts data transfer speeds as fast as 4.6 ms/scan and integration times ranging from 9 µs to 50 s.
For the light source inside the reflectometer, the HAL-S-Mini is used. The AvaLight-HAL-S-Mini is a compact, stabilized halogen light source with adjustable focusing of the fiber connection, maximizing output power at the desired wavelength. This versatile light source also has an adjustable output power to provide extra power or longer bulb life.
Figure 1: The setup of the reflectometer.
Description of Methodology:
The setup for this experiment incorporates the new Reflectometer system from Avantes. The reflectometer is an easy to use package that incorporates a halogen light source, a reflection probe and the AvaSpec-Mini to perform reflection, thin film and parylene measurements.
The new generation, our AvaSpec-Mini MK-II series (AvaSpec-Mini2048CL and AvaSpec-Mini4096CL) is definitely one of the smallest types of spectrometers on the market today. In cases where size matters, the AvaSpec CompactLine family offers spectrometers with the smallest form factor. This enables easier integration of our spectrometers into machines and handheld devices. Squeezing down the size hardly compromises the performance of the instruments, but limits the customer a bit in the number of possible configurations. Customization is possible when adequate volumes are needed. This makes the CompactLine especially suited for OEM users wanting to integrate a spectrometer into their own devices. The AvaSpec-Mini-CL series can be equipped with a 2048 pixel CMOS detector or our first-to-the-market 4096-pixel array. Enjoy the speed and enhanced native UV/NIR response of CMOS with an incredible resolution of up to 0.09 nm unavailable anywhere else. The low stray light design allows stray light levels from as low as 0.2% and the fast response time boasts data transfer speeds as fast as 4.6 ms/scan and integration times ranging from 9 µs to 50 s.
For the light source inside the reflectometer, the HAL-S-Mini is used. The AvaLight-HAL-S-Mini is a compact, stabilized halogen light source with adjustable focusing of the fiber connection, maximizing output power at the desired wavelength. This versatile light source also has an adjustable output power to provide extra power or longer bulb life.
Test Data and Results:
The following images show the thin film spectra for multiple samples:
Analysis:
Comparing the collected data with the know thickness of these samples, the AvaSpec-Mini proves to be an excellent tool for measuring the thickness of coatings. Our Parylene C sample has a known thickness of 7.00 microns, and our measurement here comes in at a calculated 6.99 +/ 0.06. This falls within the expected range and tolerance for this sample. The other three samples, A26, A40 and A66 (samples from an existing Avantes customer), all fall within the expected thickness measurement as well.
Conclusion:
The AvaSpec-Mini, in combination with the AvaLight-HAL-S-Mini, is an effective way to collect thin film and parylene measurements. The compact size of the AvaSpec-Mini allows for easy OEM integration into a number of devices across a wide range of industries, including thin film. Devices like the reflectometer show that small, compact devices can easily monitor the thin film deposition process to accurately measure thickness of thin film coatings. Finally, the third-party thin film software, created by Boulder Optical Design, demonstrates how easy it is to incorporate Avantes instruments in your own software. To see how the AvaSpec-Mini can assist you in thin film measurements, please contact your Avantes sales rep.