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Whitepaper: Semiconductor Wafer Measurement for Increased Productivity GalleryWhitepaper: Semiconductor Wafer Measurement for Increased Productivity
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Whitepaper: Semiconductor Wafer Measurement for Increased Productivity
Semiconductor Wafer Measurement for Increased Productivity This three-part article describes how manufacturers leverage capacitance-based inspection systems for semiconductor wafers. The article reviews best-practices, consequences of failing to inspect semiconductor wafers and benefits of using semi-automated, fully-automated and manual systems for wafer metrology and inspection. Part 1: Why Disc Geometry Matters in Wafer Production Semiconductor wafers are cut from cylindrical silicon crystals, or ingots. The flatness of these disc-shaped wafers is controlled to tight tolerances to ensure that the entire wafer surface is suitable for integrated circuit (IC) production. If disc geometry is out-of-spec [...]
LED SUBSTRATE THICKNESS
Industry Semiconductor Applications Photolithography Using Capacitance Sensors Measurement Type Positioning Description Remember that old acronym, GIGO? Garbage in garbage out, it can apply to raw materials as well as programming. Sapphire wafers need to be of a certain quality to ensure maximum yield. Excessive TTV, Bow, and Warp lead to premature LED failure. LED manufacturers need to inspect incoming wafers. Wafer producers also need to check and control TTV, Bow and Warp. The market for sapphire wafers, driven by the growth in LED manufacturing, is booming. While the price [...]
The Cost of Failing to Inspect Semiconductor Wafers
This is the second of three articles in Semiconductor Wafer Measurement for Increased Profitability. The first article in this series explains why disc geometry matters. The third article describes the benefits of using semi-automated, fully-automated, and manual systems for wafer metrology and inspection. Most semiconductor wafers are made of silicon, the second most common element in the Earth’s crust. Yet, silicon’s abundance does not mean that wafers are inexpensive. The pure form of silicon that’s used in semiconductors does not occur naturally and must be refined and mixed with a dopant that alters material properties and electrical characteristics. Silicon ingots are formed, wafers [...]
WAFER QA/QC AFTER SLICING AND POLISHING
Industry Semiconductor Applications Wafer Qa/Qc After Slicing And Polishing Measurement Type Surface Description When wafers are sliced up with wire saws, they are measured to make sure they are within the specified thickness, with minimal bow, warp, and TTV. After initial measurement, they are sorted and sent for polishing. Since polishing removes material and smoothes out the rough surfaces they need to be measured again to ensure they meet thickness guidelines and quality standards. Solution: MTI Instruments manufactures multiple systems to perform thickness measurements. From semi automated Proforma 300SA to manual wafer [...]
ABOUT WAFER BOW AND WARP MEASUREMENT SYSTEMS
Thickness Measurement for Metrology Systems 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). ASTM F534 3.1.2: The deviation of the center point of the median surface of a free, unclamped wafer from the median [...]
LITHOGRAPHY OPTICS POSITION FOCUS
Industry Semiconductor Applications Photolithography Using Capacitance Sensors Measurement Type 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 [...]
GAAS SUBSTRATE THICKNESS MEASUREMENT
Industry Semiconductor Applications Gaas Substrate Thickness Measurement Measurement Type Thickness Description Measuring Thickness of Wafers with Different Chemistries 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 sensor’s 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) using non-contact capacitive [...]
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 [...]
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 a lapping surface that rotates and removes unwanted material. [...]
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 [...]