6 MHz Gold Quartz sensor for use in ultra-high temperature applications up to 500 degrees C. Compatible with thin film deposition monitors and controllers, including Inficon, Maxtek, Sigma Instruments, and Sycon instruments. SQ, 14 mm diameter. Also referred to as a double-anchor electrode pattern.
All SQ crystals are packed in quantities of 1 piece/per disc. Due to the very fragile nature of the crystal, each crystal is packed in its own disc. Careful attention to the design ensures that the center of the crystal, where the actual measurement occurs (within a radius of 3 mm from the center), is not touched or contaminated by the plastic. We use pharmaceutical grade PETG plastic for the top, and hand cleaned polystyrene for the base. This difference in plastics is needed due to the buildup of static charge between two pieces of PETG. Some manufacturers use anti-static PETG, but this contains a polymer agent that will eventually leach onto the crystal surface. In other words, our packages were designed from the ground up with the same exacting standards as the crystals themselves.
SQ: The Most Advanced High Temperature Crystal
The measurement of film thickness during a vacuum deposition process can be accomplished with great accuracy and precision using a quartz crystal microbalance, or QCM. Under controlled conditions, it is possible to achieve angstrom level resolution of the film thickness. In practice, however, this is rarely achieved.
A film thickness monitor measures the change in resonance frequency of an oscillating quartz crystal while a thin film coating is collecting on its surface. As the coating builds up, the resonance frequency decreases in a very predictable fashion. If the density of the deposited film is known, the thickness of the film can be calculated in real-time.
A film thickness monitor, however, works on the underlying assumption that any change in the resonance frequency is solely a result of film build-up. Unfortunately, quartz crystals can also change resonance frequency when exposed to a thermal gradient or mechanical stress. In a typical thin film deposition, both of these phenomena exist due to either the deposition source radiation, highly energetic species (as in sputtering) or stresses caused by film condensation. Often these factors exist in concert.
Scott Grimshaw, Inventor of SuperQuartz
Noise Prevention in High Temperature Applications
For processes that operate at temperatures above 100°C, standard quartz crystals are extremely noisy. This noise prevents accurate and stable film thickness measurements. To solve this problem, Colnatec has invented monitor crystals that operate stably above 100°C, are stress-insensitive, and can operate in plasmas. The most vigorous of these, SuperQuartz (SQ), maintains operating efficiency at temperatures of 500°C+. The SuperQuartz is ideal for processes requiring intense heat, such as ALD, CVD, OVPD, high temperature PVD, and thin film furnace processes such as selenization and indiffusion.
As an added benefit, SuperQuartz crystals are able to disregard the rate spike caused by temperature variances. This usually occurs when the deposition source shutter is opened or the crystal is exposed to plasmas. Typically, this action causes a frequency shift of up to 100 Hz, which translates to rate changes of 50 angstroms or more for films such as aluminum. Further, the noise associated with the intense energy of impinging atoms in sputtering is dramatically reduced, owing to the stress-insensitivity of the crystal. These are very real advantages in the measurement of nanometer films used in the manufacture of OLEDs, precision optical interference films, or next-generation electronic devices (e.g., solar cells).
Although it can be used effectively in place of standard AT-cut quartz in all commercially available film thickness monitors and controllers, the SQ crystal is ideally used in Colnatec high temperature sensor heads like the Tempe or Phoenix sensor systems.
|Dimensions||.375 × .375 × .035 in|
1 crystal per pack