Capacitance Sensors Facilitate 3D IC Construction
Capacitance Sensors Facilitate 3D IC Construction Semiconductor, Research & Development 3D IC Construction Distance, Positioning, Displacement Description [Application Note 70518] To boost device performance, today's semiconductor and microelectronics manufacturers are building three-dimensional integrated circuits featuring vertically-stacked silicon wafers and dies. The rationale is simple. Exploiting the Z-axis avoids the power and footprint penalties associated with two-dimensional processes. Implementing the rationale, however, is not so simple. Going vertical requires coplanar surfaces to make contact with all pins, pads, and pillars. Problem Typically, manufacturers measure the angle and gap between two planes [...]
Thickness Gauge Measurement With Conductive Wafers and Thin Films
Thickness Gauge Measurement With Conductive Wafers and Thin Films Consumer Electronics Electronics Parts Profiling Thickness Description Using MTI's capacitive thickness gauge Proforma 300i with conductive wafers and thin films G = (a+b+t1+t2 ) Where G is the fixed gap between two probes When making the thickness measurement t2 can appear as t2 (film thickness) when it is a conductor, or 0 thickness when t2 is just air. So t2 will vary between the actual film thickness t2 if it's a conductor all the way down to 0 thickness if the [...]
Semiconductor Wafer Lapping and Displacement Measurement
Introduction 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 a lapping surface that rotates and removes unwanted material. The amount of material that is removed varies by device type, and the entire semiconductor [...]
MTI’s Accumeasure HD Amplifier vs. SmarAct’s PicoScale Interferometer GalleryMTI’s Accumeasure HD Amplifier vs. SmarAct’s PicoScale Interferometer
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MTI’s Accumeasure HD Amplifier vs. SmarAct’s PicoScale Interferometer
MTI's Accumeasure HD Amplifier vs. SmarAct's PicoScale Interferometer Research & Development Piezoceramic, 1-3 Pzt / Polymer Composite And Pvdf Film Amplitude Description This application note compares MTI's Accumeasure HD amplifier to SmarAct's Picoscale interferometer in terms of resolution and accuracy for very small displacement measurements. Specifically, this comparison focuses on minimum expected resolution and the effects of noise on accuracy. High resolution interferometers are widely regarded as the instrument of choice for the type of measurements described in this application note, but MTI's technology provides exceptional accuracy and stability. Moreover, the [...]
Connecting Encoders to MTI’s Digital Accumeasure
Connecting Encoders to MTI's Digital Accumeasure MTI's Digital Accumeasure D has the ability to accept one or two digital quadrature encoders. The encoders can be linear slide-type or rotary. Digital encoders allow for tracking the position of capacitive probes such that you can synchronize a probe's position with the probe's displacement data. Two common examples are: Rotary shaft runout: shaft (radial) displacement vs. angular encoder position X/Y position of probes measuring wafer thickness (map wafer thickness) Accumeasure software (basic and measurement) allows the display of instantaneous encoder counts as well as probe displacement data; however, [...]
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 [...]
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 [...]
Wafer Measurement – Ungrounded
Wafer Measurement - Ungrounded Semiconductor Wafer Measurement - Ungrounded Metrology Description MTI Instruments Inc. has developed a thickness measurement device that eliminates the effect of varying target conductivity. Called the Push-Pull probe, it’s a unique version of the AccumeasureTM amplifier series. This special design provides accurate surface information for wafer bow and warp. Bow is the deviation of the center point of the median surface of a free, un-clamped wafer from the median surface to the reference plane. Where, the reference plane is defined by three corners of equilateral triangle. This [...]
Wafer Thickness, Bow, Warp And TTV
Semiconductor Wafer Thickness, Bow, Warp And Ttv 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 face [...]