Continuous Clocking of TDI Sensors for Charge Transfer
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Solution Overview
Problem
Previous TDI sensors exhibit suboptimal functionality due to burst clocking, which results in low charge transfer efficiency, high power dissipation, sensitivity to timing jitter, and reduced modulation transfer function, making them less effective for semiconductor wafer and photomask inspections.
Innovation Solution
The use of continuous clocking with sinusoidal or composite voltage waveforms to control charge propagation between gates, minimizing net voltage fluctuations and enabling simultaneous charge transfer and readout, reducing noise and improving signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If burst clocking is used to transfer charge between pixels, then charge transfer can be achieved, but charge transfer efficiency is low and power dissipation is high
Solution Approach 1:
The patent applies periodic clocking signals with optimized duty cycles and symmetrical waveforms to drive charge transfer through the TDI sensor. By using periodic action with carefully controlled timing parameters, the system achieves efficient charge transfer while minimizing power dissipation through balanced voltage swings that reduce unnecessary current flow.
Solution Approach 2:
The patent modifies critical parameters of the clocking scheme including duty cycle, voltage amplitude, and timing synchronization between adjacent gates. By optimizing these parameters, the system resolves the contradiction between achieving reliable charge transfer and minimizing power consumption, demonstrating how parameter tuning can simultaneously improve efficiency and reduce energy loss.
2Speed
If burst clocking with sharp voltage transitions is used, then charge transfer speed can be increased, but sensitivity to timing jitter increases
Solution Approach 1:
The patent employs dynamic clocking waveforms that are continuously optimized for the operating conditions. By making the clocking scheme adaptive and dynamic rather than static, the system maintains high charge transfer speed while reducing sensitivity to timing variations. The continuous optimization of waveform parameters allows the system to respond to timing jitter rather than being vulnerable to it.
Solution Approach 2:
The patent implements preliminary synchronization and calibration of the clocking signals before charge transfer begins. By pre-establishing precise timing relationships and preparing the system in advance, the system reduces the impact of timing jitter on charge transfer accuracy, allowing high speed operation without proportionally increased sensitivity to timing variations.
3Reliability
If continuous clocking with sinusoidal waveforms is used, then charge transfer efficiency improves and power dissipation reduces, but device complexity increases
Solution Approach 1:
The patent replaces complex mechanical or hardware-based waveform generation systems with electronically synthesized sinusoidal clocking signals. By using electronic signal generation and control rather than mechanical mechanisms, the system achieves continuous optimized clocking with reduced hardware complexity. The electronic substitution allows for software-controlled waveform parameters without additional physical components.
4Productivity
If higher data rates are achieved through faster clocking, then throughput improves, but electromagnetic noise increases
Solution Approach 1:
The patent converts the potentially harmful effect of fast switching into a beneficial phenomenon by using symmetrical sinusoidal waveforms. The controlled electromagnetic fields generated by the optimized clocking scheme are harnessed to improve charge transfer efficiency while the symmetrical nature of the waveforms causes noise cancellation effects. This transforms what would normally be harmful electromagnetic interference into a useful component of the charge transfer mechanism.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the throughput and resolution of TDI sensors by reducing electronic noise, allowing faster data rates and improved signal-to-noise performance, while minimizing power dissipation and vulnerability to electromigration.
Implementation Method 1
The wafer surface reflects light onto the TDI sensor, and at the points where light strikes the sensor the sensor may generate photoelectrons
Implementation Method 2
controlling voltage waveform shapes for waveforms advancing the accumulated charge between gates in a substantially nonsquare waveform
Data Source
AI summary
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.