# US 7,609,309 B2 · Continuous clocking of TDI sensors > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,609,309 B2 - Document ID: US7609309B2 - Status: Granted - Kind: B2 - Application number: 10/992,063 - Filed: 2004-11-18 - Published: 2006-05-18 - Granted: 2009-10-27 - Earliest claimed: 2004-11-18 - Assignees: KLA-Tencor Technologies Corporation - Inventors: David Lee Brown; Yung-Ho Chuang - Web page: https://patentgrep.com/patent/US7609309B2 ## CPC - H04N 25/711: Time delay and integration [TDI] registers; TDI shift registers - H04N 25/71: Charge-coupled device [CCD] sensors; Charge-transfer registers specially adapted for CCD sensors - H04N 25/745: {Circuitry for generating timing or clock signals} - H04N 25/7795: {Circuitry for generating timing or clock signals} - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract A method and apparatus for propagating charge through a time division and integration (TDI) sensor is provided. The method and apparatus may be used with the TDI sensor to inspect specimens, the TDI sensor operating to advance an accumulated charge between gates of the TDI sensor. The design comprises controlling voltage waveform shapes for waveforms advancing the accumulated charge between gates in a substantially nonsquare waveform, such as a composite, sinusoidal, or other shaped waveform. Controlling voltage waveform shapes operates at different voltage phases in adjacent gates to provide a substantially de minimis net voltage. ## Claims ### Claim 1 A method of inspecting specimens using a time division and integration (TDI) sensor, the TDI sensor operating to advance an accumulated charge between gates of the TDI sensor, the method comprising: controlling waveforms advancing the accumulated charge between gates of the TDI sensor to be substantially nonsquare shaped waveforms wherein waveforms are controlled by operating at different voltage phases in adjacent gates to provide a substantially de minimis net voltage. ### Claim 2 (depends on 1) The method of claim 1 wherein the waveforms are controlled to generate a net substrate current on the TDI sensor of zero. ### Claim 3 (depends on 1) The method of claim 1, wherein at least one nonsquare shaped waveform is substantially sinusoidal. ### Claim 4 (depends on 1) The method of claim 1, wherein at least one nonsquare shaped waveform is substantially trapezoidal. ### Claim 5 (depends on 1) The method of claim 1, wherein at least one nonsquare shaped waveform comprises a composite waveform. ### Claim 6 (depends on 5) The method of claim 5, wherein said composite waveform comprises a fundamental sinusoidal wave operating at a line rate frequency combined with at least one odd-numbered harmonic having lower amplitude than said fundamental sinusoidal wave. ### Claim 7 (depends on 5) The method of claim 5, wherein at least one nonsquare shaped waveform further comprises an inverse of residual fluctuations created by said composite waveform. ### Claim 8 (depends on 1) The method of claim 1, wherein said TDI sensor comprises three gates per pixel, where phases of three voltage waveforms corresponding to said gates are shifted by 120 degrees compared to adjacent phases. ### Claim 9 (depends on 8) The method of claim 8, wherein the sum of the slopes of said three voltage waveforms applied to said gates is de minimis. ### Claim 10 (depends on 1) The method of claim 1, wherein said TDI sensor comprises four gates per pixel, where phases of four voltage waveforms corresponding to said gates are shifted by 90 degrees compared to adjacent phases. ### Claim 11 (depends on 10) The method of claim 10, wherein the sum of the slopes of said four voltage waveforms applied to said gates is de minimis. ### Claim 12 (depends on 1) The method of claim 1 wherein said TDI sensor comprises two gates per pixel, where phases of two voltage waveforms corresponding to said gates are shifted by 180 degrees compared to adjacent phases. ### Claim 13 (depends on 12) The method of claim 12 wherein the sum of the slopes of said two voltage waveforms applied to said gates is de minimis. ### Claim 14 (depends on 1) The method of claim 1, wherein said TDI sensor produces an image, and wherein movement of the image is substantially synchronized within less than approximately one-half pixel to the movement of stored charge on said TDI sensor. ### Claim 15 (depends on 1) The method of claim 1, wherein voltage waveform shapes are digitally synthesized. ### Claim 16 (depends on 1) The method of claim 1, wherein the TDI sensor comprises at least one readout amplifier, and wherein each readout amplifier operates while said TDI sensor transfers charge within an image area of the TDI sensor. ### Claim 17 (depends on 16) The method of claim 16, wherein each readout amplifier operates substantially continuously. ### Claim 18 A time division and integration (TDI) sensor comprising an image area, the TDI sensor comprising: a transfer gate employed to transfer charge received from the image area of the TDI sensor; and a buffer gate interposed between the image area and the transfer gate, said buffer gate operated to propagate charge through the image area of the TDI sensor using a nonsquare voltage waveform. ### Claim 19 (depends on 18) The TDI sensor of claim 18, wherein said nonsquare voltage waveform is substantially sinusoidal. ### Claim 20 (depends on 18) The TDI sensor of claim 18, wherein said nonsquare voltage waveform comprises a composite waveform. ### Claim 21 (depends on 18) The TDI sensor of claim 18, wherein said TDI sensor comprises at least two gates per pixel, where phases of voltage waveforms corresponding to each of said gates are shifted by 360 degrees divided by the number of gates per pixel as compared to adjacent phases. ### Claim 22 (depends on 21) The TDI sensor of claim 21, wherein the sum of the slopes of all voltage waveforms applied to said gates is de mimmis. ### Claim 23 (depends on 18) The TDI sensor of claim 18, further comprising at least one readout amplifier, and wherein each readout amplifier operates while said TDI sensor transfers charge within the image area of the TDI sensor. ### Claim 24 (depends on 23) The TDI sensor of claim 23, wherein each readout amplifier operates substantially continuously. ### Claim 25 (depends on 18) The TDI sensor of claim 18, further comprising a substrate comprising impurity atoms proximate at least one buffer gate. ### Claim 26 (depends on 25) The TDI sensor of claim 25, wherein said impurity atoms form a barrier inhibiting movement of charge from at least one transfer gate back into at least one buffer gate. ### Claim 27 A method of advancing accumulated charge in a time delay and integration (TDI) sensor, said TDI sensor comprising an image area and further comprising a buffer gate located between the image area and a transfer gate, the method comprising: controlling voltage waveform shapes advancing the accumulated charge between gates within the image area of the TDI sensor, wherein said controlling comprises applying a composite waveform voltage to said buffer gate. ### Claim 28 (depends on 27) The method of claim 27, wherein the composite waveform voltage comprises a voltage increasing relatively slowly to a peak value, followed by a sharp dropoff. ### Claim 29 (depends on 27) The method of claim 27 wherein the voltage waveform shapes are controlled to generate a net substrate current on the TDI sensor of zero. ### Claim 30 (depends on 27) The method of claim 27, wherein said TDI sensor comprises a first plurality of gates per pixel, where phases of voltage waveforms corresponding to said gates are shifted by 360 degrees divided by the first plurality as compared to adjacent phases. ### Claim 31 (depends on 30) The method of claim 30, wherein the sum of the slopes of said voltage waveforms applied to said gates is de minimis. ### Claim 32 (depends on 27) The method of claim 27, wherein said TDI sensor produces an image, and wherein movement of the image is substantially synchronized within less than approximately one-half pixel to the movement of stored charge on said TDI sensor. ### Claim 33 (depends on 27) The method of claim 27, wherein the TDI sensor comprises at least one readout amplifier, and wherein each readout amplifier operates while said TDI sensor transfers charge within the image area of the TDI sensor. ### Claim 34 (depends on 33) The method of claim 33, wherein each readout amplifier operates substantially continuously. ### Claim 35 A method for controlling voltage waveform shapes between gates in a time delay and integration (TDI) sensor, the TDI sensor comprising a buffer gate located between an image area and a transfer gate, comprising: applying a digital voltage wave to said transfer gate; and applying an inverted voltage wave to said buffer gate, wherein said inverted voltage wave is inverted with respect to the digital voltage wave applied to said transfer gate. ### Claim 36 (depends on 35) The method of claim 35 wherein the digital voltage wave and inverted voltage wave are controlled to generate a net substrate current on the TDI sensor of zero. ### Claim 37 (depends on 35) The method of claim 35, wherein said TDI sensor comprises a first plurality of gates per pixel, where phases of voltage waveforms corresponding to said gates are shifted by 360 degrees divided by the first plurality as compared to adjacent phases. ### Claim 38 (depends on 35) The method of claim 35, wherein the sum of the slopes of said voltage waveforms applied to said gates is de mimmis. ### Claim 39 (depends on 35) The method of claim 35, wherein said TDI sensor produces an image, and wherein movement of the image is substantially synchronized within less than approximately one-half pixel to the movement of stored charge on said TDI sensor. ### Claim 40 (depends on 35) The method of claim 35, wherein the TDI sensor comprises at least one readout amplifier, and wherein each readout amplifier operates while said TDI sensor transfers charge within the image area of the TDI sensor. ### Claim 41 (depends on 40) The method of claim 40, wherein each readout amplifier operates substantially continuously. ### Claim 42 A method of controlling charge propagation in a time division and integration (TDI) sensor, comprising: controlling voltage waveform shape advancing an accumulated charge from gate to gate within a serial register area of said TDI sensor; wherein the voltage waveform shapes are controlled to generate a de minimis net substrate current on the TDI sensor. ### Claim 43 (depends on 42) The method of claim 42, wherein said TDI sensor comprises a first plurality of gates per pixel, where phases of voltage waveforms corresponding to said gates are shifted by 360 degrees divided by the first plurality as compared to adjacent phases. ### Claim 44 (depends on 43) The method of claim 43, wherein the sum of the slopes of said voltage waveforms applied to said gates is de mimmis. ### Claim 45 (depends on 42) The method of claim 42, wherein said TDI sensor produces an image, and wherein movement of the image is substantially synchronized within less than approximately one-half pixel to the movement of stored charge on said TDI sensor. ### Claim 46 (depends on 42) The method of claim 42, wherein the TDI sensor comprises at least one readout amplifier, and wherein each readout amplifier operates while said TDI sensor transfers charge within an image area of the TDI sensor. ### Claim 47 (depends on 46) The method of claim 46, wherein each readout amplifier operates substantially continuously. ### Claim 48 (depends on 42) The method of claim 42 wherein said voltage waveforms are substantially sinusoidal. ### Claim 49 (depends on 42) The method of claim 42 wherein said voltage waveforms are nonsquare. ### Claim 50 (depends on 42) The method of claim 42 wherein said voltage waveforms are composite waveforms comprising a fundamental sinusoidal wave operating at pixel readout frequency added at least one odd-numbered harmonic having lower amplitude than said fundamental sinusoidal wave. ### Claim 51 A TDI sensor comprising a serial register and floating diffusion region, the TDI sensor comprising: a serial buffer gate interposed between the serial register area and the floating diffusion region configured to serially move charge from registers in the serial register area to the floating diffusion region using a composite waveform. ### Claim 52 (depends on 51) The TDI sensor of claim 51, wherein said composite waveform comprises smooth continuous features and discontinuous features. ### Claim 53 A TDI sensor comprising: a buffer gate interposed between a serial register area and a floating diffusion region, wherein said buffer gate is operated continuously when operation of the serial register area stops. ### Claim 54 (depends on 51) The TDI sensor of claim 51, wherein the serial buffer gate has a serial buffer gate waveform comprising a square wave. ### Claim 55 (depends on 51) The TDI sensor of claim 51, wherein the serial buffer gate has a serial buffer gate waveform comprising a composite waveform including a sinusoidal portion and a step portion. ### Claim 56 (depends on 51) The TDI sensor of claim 51, wherein the serial buffer gate has a serial buffer gate waveform comprising a continuous composite waveform. ### Claim 57 (depends on 53) The TDI sensor of claim 53, wherein continuous operation of said buffer gate enables receiving signal charge from an image region of the TDI sensor. ### Claim 58 A method of controlling charge propagation in a TDI sensor, comprising: employing a fundamental frequency and significant harmonic TDI sensor drive waveforms that vary in frequency in proportion to an operating line rate of the TDI sensor. ### Claim 59 (depends on 58) The method of claim 58 wherein the fundamental frequency and significant harmonic TDI sensor drive frequencies comprise voltage waveform shapes that are controlled to generate a net substrate current on the TDI sensor of zero. ### Claim 60 (depends on 59) The method of claim 59, wherein said TDI sensor comprises a first plurality of gates per pixel, where phases of voltage waveforms corresponding to said gates are shifted by 360 degrees divided by the first plurality as compared to adjacent phases. ### Claim 61 (depends on 60) The method of claim 60, wherein the sum of the slopes of said voltage waveforms applied to said gates is de minimis. ### Claim 62 (depends on 58) The method of claim 58, wherein the TDI sensor comprises at least one readout amplifier, and wherein each readout amplifier operates while said TDI sensor transfers charge within an image area of the TDI sensor. ### Claim 63 (depends on 62) The method of claim 62, wherein each readout amplifier operates substantially continuously. ### Claim 64 A time division and integration (TDI) sensor comprising a plurality of gates, comprising: means for controlling voltage waveform shapes for waveforms advancing an accumulated charge between the gates of the TDI sensor using substantially nonsquare waveforms, wherein said voltage waveform shape controlling means operates adjacent gates at different voltage phases thereby providing a substantially de minimis net voltage. ### Claim 65 (depends on 64) The TDI sensor of claim 64 wherein the voltage waveform shape controlling means operates to generate a net substrate current on the TDI sensor of zero. ### Claim 66 (depends on 64) The TDI sensor of claim 64, wherein said nonsquare voltage waveform is substantially sinusoidal.