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Annual Report Extention to PVSCAN

Annual Report Extention to PVSCAN. Artak Hambarian NREL, August, 2007. Outline. The goal of the project Preliminary calculations (excel) Block diagram Components: + Mechanics; + Optics; + Analog Electronics; + Digital Electronics/Data Streaming; + Motion Control; + Software. Providers

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Annual Report Extention to PVSCAN

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  1. Annual Report Extention to PVSCAN Artak Hambarian NREL, August, 2007

  2. Outline • The goal of the project • Preliminary calculations (excel) • Block diagram • Components: + Mechanics; + Optics; + Analog Electronics; + Digital Electronics/Data Streaming;+ Motion Control;+ Software. • Providers • Current Status

  3. The goal of the project • To achieve rapid polar scanning of semiconductor wafers up to 300 mm (12”) in diameter for specularity detection with resolution of 10µ in the first phase, and 1-2µ in the second phase • In the second phase PL and OBIC can be added, Cartesian scan employed.

  4. Preliminary calculations • Modes of polar scan: constant angular velocity (CAV); constant linear velocity (CLV). • CAV: the number of dots on ONE loop defines the data acquisition rate at a given rpm. • CLV: the number of dots on the LARGEST loop defines the data acquisition rate at a given rpm.

  5. CAV and CLV Number of points = N Number of points = N/2

  6. Preliminary calculations (excel)

  7. Preliminary calculations (excel) 2

  8. Block Diagram Analog amplifier Linear stage, encoder, r Optical probe ADC, Data streaming, PC, User Innterface, Drivers, VI-s. wafer Motion Control Spindle, j encoder

  9. Components • Mechanics: table, granite substrate, spindle, vacuum chuck, linear stage. • Optics: optical probe • Motion Control: encoders, multipliers, processor • Analog Electronics: amplifiers • Digital Electronics/Data Streaming: ADC-s, Counter, Processor, PXI/…e. • Software: User Interface, VI-s, drivers, PC transformation, pattern recognition, storage management, etc.

  10. Mechanics, requirements

  11. Mechanical design

  12. Mechanics: table support

  13. Mechanics • Table:- designed by AUA and YPI;- to be manufactured by YPI • Other components: granite substrate, spindle, vacuum chuck, linear stage:- designed by AUA and YPI;- to be manufactured by AeroTech Inc, Pittsburg, PA.

  14. Optics • Optical probe, in process, to be designed and manufactured by NREL. • Laser:- CW- Stability- Noise • Photodetectors (PD): low noise, high speed avalanche PD.

  15. Analog Electronics: amplifiers • Thermal Stability • Noise • Input/output impedances to deal with capacities of the photodiodes. • Output impedances to deal with ADC (50 W input through coaxial cable).

  16. Trans-Impedance Preamplifier

  17. Motion Control, Data streaming, Synchronization

  18. Motion Control • Performs the displacement and takes the signal about the displacement from encoders • Provides displacement pulses at clock frequency (40 MHz, through multiplier) and absolute coordinate at lower frequency (4 kHz). • Communicates through PCI or PXI bus. • Performs backlash and other software driven controls.

  19. Data streaming • Analog to digital conversion (ADC) • Counts of steps and synchronization • Digital signal processing for:- interleaving: omission of signals that do not carry information- on-fly pattern recognition (here or in the main processor)- laser noise cancelling- Other noise reduction algorithms (in process)

  20. Data streaming

  21. Data streaming • The sampling rate of analogue signals is assumed to be from 2.5Ms/sec to 40Ms/sec • ADC resolution is 14 bit, we use only 8 bit. • for four sensors requires from 4x8bitx2.5Ms/sec = 80Mbit/sec to 4x8bitx40Ms/sec = 1.28Gbit/sec summary capacity of communication channel and signal processing speed

  22. Data streaming • The system is based on PXI express / PXI components mounted into the NI PXIe-1062Q chassis • consists of:- two NI PXI-5142 digitizers, - NI PXI-6602 counter, - NI PXIe-6259 Input/Output module and - NI PXIe-8105 controller.

  23. ADC-s, NI PXI-5142 digitizers Each of the two digitizers receives two amplified analogue signals from photo sensors

  24. On board signal processing gain control, offset control, frequency translation, filtering, decimation and interleaving

  25. On board DSP • The filtering is employed in level selection operation during the high precision scanning, which has the reason not to record the data points when scanned segment is clear from defects. • By choosing the threshold level equal to the background noise it will be possible to discard all not necessary sampled data points.

  26. On board DSP • The interleaving process allows to combine the necessary data points into data packets by means of the initial buffering and then to transmit packets at lower data rate without transmission of zero information bytes. • It strongly decreases the data transmission rate through the PXIe/PXI bus

  27. Synchronization - I/O PXIe-6259 module

  28. Laser • CW • Stability • Noise • Noise cancelling algorithm.

  29. Software • User Interface • Polar  Cartesian transformation • VI-s for interleaving • On-fly pattern recognition and indication • Storage management (making smaller files for storage) • Simultaneous various size files creation for easy zooming.

  30. User Interface

  31. System Integration • Excel

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