Semiconductor Wafer Lapping and Displacement Measurement
Semiconductor Wafer Lapping and Displacement Measurement Semiconductor Semiconductor Wafer Manufacturing Displacement Description Semiconductor Wafer Lapping and Displacement Measurement This application note explains how MTI’s Accumeasure technology was used with a lapping machine to measure displacement (wafer material removal) and determine the new semiconductor wafer thickness. Changes in electrical capacitance (displacement) were measured and then directly converted into a 24-bit digital reading to obtain precise digital thickness measurements. During lapping, a wafer of known start thickness is placed on a rotary lapping table. The backside of the wafer faces downward and toward [...]
Time Resolved Spectroscopy of Protein Crystals
Time Resolved Spectroscopy of Protein Crystals Customer Case The customer is involved in Time Resolved Spectroscopy of protein crystals. This involves shooting a laser onto the protein crystals and measuring the pulses generated by the crystals (as they are projected out of the sample) and their decay over time. Due to the very noisy nature of the return signals, it is essential to average many pulses in order to recover the pulse shape and measure the decay. The decay takes place over many tens of milliseconds, so it is necessary to acquire very long records (in the order of [...]
Wafer Stress Analysis Using the 300iSA
Wafer Stress Analysis Using MTI Instruments Proforma 300iSA Wafer processing involves several stages that can lead to mechanical changes in the wafer structure. These changes, or stresses, may result in deformities, making the wafer either unusable or only marginally usable. To evaluate these stresses and determine the wafer's quality, wafer stress measurement is essential. The Proforma 300iSA wafer characterization tool offers a powerful solution for wafer stress analysis. It allows for the analysis of a wafer both before and after processing. By comparing these two states, the Proforma 300iSA effectively evaluates the wafer's stress levels and mechanical alterations, providing [...]
Hyper Remote Laser Sensor
Hyper Remote Laser Sensor Customer Case The customer is at the prototype stage for building a hyper remote sensor which will fly over the ocean and be able to see 100 to 200 feet below the surface. The sensor is being designed in order to determine the composition of the ocean and the ocean floor. This remote sensor will be extremely useful in the detection of pollution and studying the way pollution is being distributed by ocean currents. It will also be useful to the military (navy) for creating mine-finding systems. A deep blue laser will be used to [...]
Laser Induced Fluorescence (LIF)
Laser Induced Fluorescence (LIF) Customer Case A customer has developed a breakthrough technique for the application of laser-induced fluorescence (LIF) detection to high performance liquid chromatography, capillary e lectrophoresis, sequencing and microbial analysis. The technique involves using fluorescence decay curves at multiple wavelengths simultaneously, leading to true 3-D fluorescence spectroscopy (i.e., fluorescence intensity as a function of wavelength and delay time relative to pulsed excitation). They have a requirement to increase the laser pulse repetition frequency (PRF) from 20-50 pulses per second to 500-1000 pulses per second. Basically, they want to collect and time resolve the fluorescence signal for [...]
Optical Spectroscopy
Optical Spectroscopy Customer Case A customer who is completing his doctorate in Chemistry at the California Institute of Technology has identified the need to measure fast optical signals using fast photo-detectors. The signal pulse width is as short as 2ns. Signals will be acquired at a 1KHz repetition rate, with a record length of 1,000 to 10,000 data points. GaGe Case Solution The CompuScope 82G, an 8-bit, 2GS/s A/D and Scope card for PCI Bus, is the best solution for this customer. With relatively small record sets, the customer is able to keep up with the 1KHz Pulse Repeat [...]
Capacitance Probes vs. Strain Gauges in Piezo Flexure Stages
Capacitance probes with pico-positioning sensors can be embedded in piezo flexure stages. With minor mounting modifications, these non-contact probes provide significantly greater accuracy than strain gauges. Piezo flexure stages are positioning devices with a high degree of resolution. These motion stages contain a piezoelectric actuator that converts an electrical signal into displacement based on the reverse piezoelectric effect, which is the ability of a piezo electric material to elongate when a voltage is applied. When a voltage (e.g., 0-150 VDC) is applied to the actuator, the stage moves in proportion to the applied voltage. Yet, the exact position remains [...]
Kinetics of Protein Dynamics
Kinetics of Preotein Dynamics Customer Case The customer is measuring kinetics of protein dynamics with a time scale of between a few nanoseconds and about a hundred milliseconds. The customer's two response signals occur after a few-nanosecond-pulse excitation that repeats at a rate of 1-10Hz. This requires a bandwidth from DC to a few hundred MHz, sampling speed of about 1-2GS/s, and processing time for one acquisition that is less than 1-0.1secs. An analog signal of about 10-30mV comes from a Photo-Multiplier Tube (PMT) or a photo-diode with a trans-impedance pre-amplifier. The customer is currently using a couple of [...]
Radioactive Nuclear-Decay Detection
Radioactive Nuclear-Decay Detection Customer Case The customer has a requirement for PC-based waveform digitizer cards to digitize shaped pulses derived from nuclear-decay detectors. These pulses vary in their rate (frequency of occurrence) and amplitude. Their shape is approximately Gaussian with a full-width at half the maximum amplitude (FWHM) of 3-5 microseconds. The characterization of each pulse is critical for the accurate and precise determination of the activity of radioactive materials. These materials have very low count-rates (0.02 pulses per minute) to relatively high count-rates (>1000 pulses per minute). Important to the measurement process are the speed and reliability of [...]
Neutrino Detection System
Neutrino Detection System Customer Case Neutrinos are tiny (possibly massless) neutral elementary particles which interact with matter via the weak nuclear force. The weakness of the weak force gives neutrinos the property that matter is almost transparent to them. The sun, and all other stars, produce neutrinos copiously due to nuclear fusion and decay processes within the core. Since they rarely interact, these neutrinos pass through the sun and the earth (and you) unhindered. Other sources of neutrinos include exploding stars (supernovae), relic neutrinos (from the birth of the universe) and nuclear power plants (in fact a lot of [...]