Blogs
Wafer Characterization
Semiconductor Wafer Characterization Surface Description Thickness Measurement ASTM F657: The distance through a wafer between corresponding points on the front and back surface. Thickness is expressed in microns or mils (thousandths of an inch). Total Thickness Variation (TTV) ASTM F657: The difference between the maximum and minimum values of thickness encountered during a scan pattern or series of point measurements. TTV is expressed in microns or mils (thousandths of an inch). Figure above shows a wafer placed between two non-contact measurement probes. By monitoring changes between the upper probe [...]
Solenoid Door Latches
Solenoid Door Latches Aviation/ Aerospace Solenoid Door Latches Displacement Description A key supplier to the aerospace industry who manufactures many types of solenoid door latches was faced with the requirement to measure the motion of the lock plunger. Since the solenoid latch needs to complete the locking or unlocking cycle in as quickly as 13 milliseconds, it was critical to accurately track the fast motion of the plunger with a measurement system having a frequency response in excess of 100kHz. Because of the limited access to the interior of the [...]
Fiber Optic Probes Measure Stator Bar Vibration
Fiber Optic Probes Measure Stator Bar Vibration Power Generation, Industrial Stator Bar Vibration In A High Magnetic Field Amplitude Description [Application Note 11718] One of the primary concerns in large generator design is vibration. Excessive vibration can lead to premature breakdown of insulation and other materials, ultimately resulting in early failure of the generator itself. The Problem A leading manufacturer of power generating equipment required a sensing system able to measure stator bar vibration in a partial generator mockup. Specifically, the company's multi-day testing program demanded a sensing system that was [...]
Nuclear Heat Exchanger Vibration
Nuclear Heat Exchanger Vibration Power Generation Nuclear Heat Exchanger Vibration Amplitude Description Introduction: Power plants, particularly nuclear power plants, require heat exchangers to cool down the primary working fluid for the power plant. Excessive vibration can lead to cracking and premature failure of the heat exchanger. Problem: A major power plant company approached MTI looking for a sensor that could measure vibration of a heat exchanger assembly that was immersed under water. Additionally, the water could reach 250 F and up to 220 PSI; the probe had to be sealed [...]
In-Situ Particle Detection
In-Situ Particle Detection Research & Development In-Situ Particle Detection Presence/Absence Description Introduction:  Foreign particles in food stuffs, plant produce, grains, etc. can lead to customer dissatisfaction when the items are packaged for sale. In some cases — it can be dangerous. Opportunity:  A major cigarette producer contacted MTI Instruments requesting a system to detect extraneous material, metal, plastic, filter fiber, and other contaminants. Background:  A cigarette’s dielectric footprint is controlled by the tobacco packing density, moisture content and the type of tobacco leaf. - packing density is controlled by the [...]
Piezoelectric Stack Motion
Piezoelectric Stack Motion Research & Development Piezoelectric Stack Motion Displacement Description Fotonic sensors are ideal for making dynamic measurement of very small oscillatory motions. Using the MTI-2100 with a spectrum analyzer, angstrom level measurements are possible. Would you like to know more? Okay let’s set up some basic equipment and get started. Piezoelectric crystals expand and contract when voltage is applied across the stack. By controlling the amplitude of the applied signal we control the magnitude of the displacement. The test setup A Spectrum Analyzer A Signal Generator to drive piezo device [...]
Thickness and TTV of Semiconducting Wafers
Thickness and TTV of Semiconducting Wafers Semiconductor Thickness And TTV Of Semiconducting Wafers Thickness Description Introduction:  Silicon wafers are ordinarily highly conductive and easy to measure with standard capacitive displacement sensors (See MTI’s Proforma 300i). Measuring the thickness of GaAs wafers that have high bulk resistivity (>10k Ohm/cm) is a little more difficult because the wafers act as non-conductive insulators in a capacitive sensors measuring field. Fortunately, MTI has a solution to this problem. Solution:  It’s possible to measure the thickness and TTV of high resistivity semiconducting wafers (like GaAs) [...]
Lithography Optics Position Focus
Lithography Optics Position Focus Semiconductor Lithography Optics Position Focus Positioning Description One specific area where capacitance systems excel is high resolution focusing of complex lens systems such as those found in atomic force microscopes, vision inspection machines and photolithography tools. In a multi-million dollar photolithography tool, high accuracy, nanometer resolution and maximum thermal stability are absolutely critical to maintain proper focus and obtain integrated circuit line widths as small as 45 nanometers. Additionally, most systems demand low power consumption and maximum heat dissipation to eliminate any adverse affects from temperature [...]
Using Laser Technology to Detect Fatigue Cracks
Using Laser Technology to Detect Fatigue Cracks Aviation/ Aerospace Jet Turbine Blade Vibration Amplitude Description In order to simulate real world conditions turbine blades are vibrated in a sound chamber at a variety of elevated temperatures. A siren directs a blast of pulsed air at the leading edge of the turbine blade creating a tremendous amount of force. This force excites the turbine blade at its resonant frequency, inducing strain in the blade structure. To accurately monitor vibration amplitude and frequency, a non-contact measurement sensor is required. Non-contact eliminates any “mass [...]
Push-Pull Capacitance Sensor Measures Ungrounded Targets
Push-Pull Capacitance Sensor Measures Ungrounded Targets Solar, Semiconductor Measurement of Ungrounded Targets Thickness, Metrology Description [Application Note 50318] Today’s semiconductor and solar industries drive the demand for thinner wafers to conserve silicon and fulfill new IC applications. To meet this demand, wafer fabricators seek greater dimensional control of their silicon products. Non-contacting capacitance sensors offer the precision, accuracy, and speed needed to measure flatness, thickness variation, and other critical dimensions. Typically, the standard capacitance sensor acts as one plate of a classical two-plate capacitive gap measurement scenario. The grounded target [...]