Various methods and systems for utilizing design data in combination with inspection data are provided. One computer-implemented method for binning defects detected on a wafer includes comparing portions of design data proximate positions of the defects in design data space. The method also includes determining if the design data in the portions is at least similar based on results of the comparing step. In addition, the method includes binning the defects in groups such that the portions of the design data proximate the positions of the defects in each of the groups are at least similar. The method further includes storing results of the binning step in a storage medium.

Methods and systems for utilizing design data in combination with inspection data

A tutorial survey is presented of the many composite filter designs proposed for distortion-invariant optical pattern recognition. Remarks are made throughout regarding areas for further investigation.

Tutorial survey of composite filter designs for optical correlators.

A method and apparatus for optically inspecting a display employs sub-pixel accuracy for each primary color to take into account angle of rotation. The method includes capturing images of a display with R×S sensors; determining sets of sensor coordinates mapping to a pixel, determining multiple misalignment angles between the pixel on the display and the R×S sensors, determining multiple x scaling ratios, determining multiple weighting factors associated with R×S sensors in response to the corresponding multiple misalignment angle and the corresponding multiple x and y scaling ratios, determining multiple luminance values for R×S sensors, determining multiple total luminance values in response to the weighting factors and the luminance values, forming scaled images including first and second luminance values, and inspecting the scaled image to identify potential defects of the pixel on the display.

Method and apparatus for optical inspection of a display

Various methods and systems for determining a position of inspection data in design data space are provided. One computer-implemented method includes determining a centroid of an alignment target formed on a wafer using an image of the alignment target acquired by imaging the wafer. The method also includes aligning the centroid to a centroid of a geometrical shape describing the alignment target. In addition, the method includes assigning a design data space position of the centroid of the alignment target as a position of the centroid of the geometrical shape in the design data space. The method further includes determining a position of inspection data acquired for the wafer in the design data space based on the design data space position of the centroid of the alignment target.

Methods and systems for determining a position of inspection data in design data space

Computer-implemented methods and systems for detecting defects in a reticle design pattern are provided. One computer-implemented method includes acquiring images of the reticle design pattern using a sensor disposed on a substrate arranged proximate to an image plane of an exposure system configured to perform a wafer printing process using the reticle design pattern. The images illustrate how the reticle design pattern will be projected on a wafer by the exposure system at different values of one or more parameters of the wafer printing process. The method also includes detecting defects in the reticle design pattern based on a comparison of two or more of the images corresponding to two or more of the different values.

Methods and systems for detecting defects in a reticle design pattern

A system for detecting defects on a moving web having a sequential series of identical frames uses an imaging device to form a real-time camera image of a frame and a comparitor to comparing elements of the camera image with corresponding elements of an image of an exemplar frame. The comparitor provides an acceptable indication if the pair of elements are determined to be statistically identical; and a defective indication if the pair of elements are determined to be statistically not identical. If the pair of elements is neither acceptable nor defective, the comparitor recursively compares the element of said exemplar frame with corresponding elements of other frames on said web until one of the acceptable or defective indications occur.

Sequential detection of web defects

The experimental results from an acousto-optic image correlator
are presented. The performance ofthis system, which is evaluated in terms
of the peak-to-sidelobe ratio, is shown to be improved by subtracting off
the signal-dependent bias terms. These bias terms can be optically generated
using the same acousto-optic correlator. Structured background
features in the input scene can also dramatically affect the correlation
result. This paper suggests a novel implementation of the difference-squared
error algorithm using a modified acousto-optic architecture that can discriminate
better than conventional correlation in scenes with structured
background features. Experimental results from real-time systems constructed
in the laboratory are presented.

Acousto-optic signal processing for real-time image recognition

Binary phase-only filters (BPOFs) are a viable candidate for the replacement of matched filters in real-time image processing and pattern recognition applications The original BPOFs were binarized versions of the real or imaginary parts of the Fourier transform Recently, a filter has been proposed that is the binarized Hartley transform In this paper, the noise performance of the binarized Hartley phase-only filter is analyzed and compared with other BPOFs as well as with the phase-only and matched filters It is well known that the matched filter optimizes the signal-to-noise ratio Further, it can be shown that the matched filter phase is the optimum phase-only filter A bound on the BPOF signal-to-noise ratio relative to that of the phase-only filter is derived Finally, the analysis is applied to the generalized form of the binarized Hartley transform

Analysis Of Binarized Hartley Phase-Only-Filter Performance With Respect To Stochastic Noise

The design and development of a compact acousto-optic image correlator capable of 
performing real-time correlations on grayscale imagery will be described. The system utilizes 
one-dimensional optical devices to perform the desired two-dimensional correlation. The 
two-dimensional correlation is performed as a series of multichannel time-integrating 
correlations between each input image line and a reference template that is stored in an 
electronic memory. The rows of the reference template are introduced into the processor in 
parallel using a one-dimensional laser diode array. The correlation in the vertical direction is 
performed using a modified charge-coupled device (CCD) operating in the shift-and-add 
mode. A laser diode array, as opposed to an LED array used in previous systems, provides 
more power so that full use can be made of the dynamic range capabilities of the acoustooptic 
device and CCD. Key features of the system will be presented, including the random 
access template memory, the custom laser diode array consisting of 64 individually addressed 
laser diodes, and the custom optical design to achieve nearly diffraction-limited image quality 
and compactness.

Compact real-time acousto-optic image correlator

Two types of optical correlators have been built to investigate real-time pattern recognition. The first employs one-dimensional devices to perform the two dimensional correlation in real time. This architecture uses an array of light emitting diodes (LED's) to input an electronically stored reference image into the processor in parallel. The input scene data is introduced into the processor one line at a time using an acousto-optic device (AOD). Multichannel time integrating correlations are performed in the row direction using the AOD and in the column direction using a charge coupled device (CCD) operating in the time delay and integrate mode. A processor has been built using this technology which correlates a 64 x 44 pixel binary reference image with a 256 x 232 input scene at video rates. The second correlator is a space integrating Fourier transform based correlator. A magneto optic-device (MOD) is used at the Fourier transform plane to rapidly change filter functions. The binary nature of the MOD device necessitates using either a binary phase or binary amplitude representation of the desired complex filter function. For this reason, several types of Binary Phase-Only Filter (BPOF) representations have been analyzed and experimentally investigated. Experimental correlation results have been obtained using both the Hartley BPOF and a newly developed class of complex binary filters, called Quad-Phase-Only Filters (QPOF). The performance of the two systems will be compared on the basis of processing speed, space bandwidth product, processor size and light efficiency. The inherent differences between incoherent and coherent processing and their implications for filter design will also be discussed. Finally, estimates of future performance will be presented.

K. Terry Stalker

Papers

Sequential detection of web defects

Acousto-optic signal processing for real-time image recognition

Analysis Of Binarized Hartley Phase-Only-Filter Performance With Respect To Stochastic Noise

Compact real-time acousto-optic image correlator

A comparison of real-time optical correlators for pattern recognition