Bt Imaging Pty Limited

Thorsten Trupke

Robert Andrew Bardos

Juergen Weber

Ian Andrew Maxwell

Kenneth Edmund Arnett

Peter Wilhelm Wurfel

Methods and systems are presented for analysing semiconductor materials as they progress along a production line, using photoluminescence images acquired using line-scanning techniques. The photoluminescence images can be analysed to obtain spatially resolved information on one or more properties of said material, such as lateral charge carrier transport, defects and the presence of cracks. In one preferred embodiment the methods and systems are used to obtain series resistance images of silicon photovoltaic cells without making electrical contact with the sample cell.

Methods for inspecting semiconductor wafers

Methods and systems are presented for analyzing semiconductor materials as they progress along a production line, using photoluminescence images acquired using line-scanning techniques. The photoluminescence images can be analyzed to obtain spatially resolved information on one or more properties of said material, such as lateral charge carrier transport, defects and the presence of cracks. In one preferred embodiment the methods and systems are used to obtain series resistance images of silicon photovoltaic cells without making electrical contact with the sample cell.

Methods () and systems () for inspecting an indirect bandgap semiconductor structure () are described. A light source () generates light () suitable for inducing photoluminescence in the indirect bandgap semiconductor structure (). A short-pass filter unit () reduces long-wavelength light of the generated light above a specified emission peak. A collimator () collimates () the light. A large area of the indirect bandgap semiconductor structure () is substantially uniformly and simultaneously illuminated () with the collimated, short-pass filtered light. An image capture device () captures () images of photoluminescence simultaneously induced by the substantially uniform, simultaneous illumination incident across the large area for the indirect bandgap semiconductor structure. The photoluminescence images are image processed () to quantify spatially resolved specified electronic properties of the indirect bandgap semiconductor structure () using the spatial variation of the photoluminescence induced in the large area.

Method and system for inspecting indirect bandgap semiconductor structure

Embodiments of methods and systems for identifying or determining spatially resolved properties in indirect bandgap semiconductor devices such as solar cells are described. In one embodiment, spatially resolved properties of an indirect bandgap semiconductor device are determined by externally exciting the indirect bandgap semiconductor device to cause the indirect bandgap semiconductor device to emit luminescence (), capturing images of luminescence emitted from the indirect bandgap semiconductor device in response to the external excitation (), and determining spatially resolved properties of the indirect bandgap semiconductor device based on a comparison of relative intensities of regions in one or more of the luminescence images ().

Method and system for testing indirect bandgap semiconductor devices using luminescence imaging

A method is disclosed whereby luminescence images are captured from as-cut or partially processed bandgap materials such as multicrystalline silicon wafers. These images are then processed to provide information about defects such as dislocations within the bandgap material. The resultant information is then utilized to predict various key parameters of a solar cell manufactured from the bandgap material, such as open circuit voltage and short circuit current. The information may also be utilized to apply a classification to the bandgap material. The methods can also be used to adjust or assess the effect of additional processing steps, such as annealing, intended to reduce the density of defects in the bandgap materials.

Wafer imaging and processing method and apparatus

Methods are presented for separating the effects of background doping density and effective minority carrier lifetime on photoluminescence (PL) generated from semiconductor materials. In one embodiment the background doping density is measured by another technique, enabling PL measurements to be analyzed in terms of effective minority carrier lifetime. In another embodiment the effective lifetime is measured by another technique, enabling PL measurements to be analyzed in terms of background doping density. In another embodiment, the effect of background doping density is removed by calculating intensity ratios of two PL measurements obtained in different spectral regions, or generated by different excitation wavelengths. The methods are particularly useful for bulk samples such as bricks or ingots of silicon, where information can be obtained over a much wider range of bulk lifetime values than is possible with thin, surface-limited samples such as silicon wafers. The methods may find application in solar cell manufacturing.

Separation of doping density and minority carrier lifetime in photoluminescence measurements on semiconductor materials

A method is disclosed whereby luminescence images are captured from as-cut or partially processed bandgap materials such as multicrystalline silicon wafers. These images are then processed to provide information is then utilized to predict various key parameters of a solar cell manufactured from the bandgap material, such as open circuit voltage and short circuit current. The information may also be utilized to apply a classification to the bandgap material. The methods can also be used to adjust or assess the effect of additional processing steps, such as annealing, intended to reduce the density of defects in the bandgap materials.

Methods and systems are presented for acquiring photoluminescence images () of silicon solar cells and wafers () as they progress along a manufacturing line (). In preferred embodiments the images are acquired while maintaining motion of the samples. In certain embodiments photoluminescence is generated with short pulse, high intensity excitation, () for instance by a flash lamp () while in other embodiments images are acquired in line scanning fashion. The photoluminescence images can be analysed to obtain information on average or spatially resolved values of one or more sample properties such as minority carrier diffusion length, minority carrier lifetime, dislocation defects, impurities and shunts, or information on the incidence or growth of cracks in a sample.

In-line photoluminescence imaging of semiconductor devices

Methods are presented for separating the effects of background doping density and effective minority carrier lifetime on photoluminescence (PL) generated from semiconductor materials. In one embodiment the background doping density is measured by another technique, enabling PL measurements to be analyzed in terms of effective minority carrier lifetime. In another embodiment the effective lifetime is measured by another technique, enabling PL measurements to be analyzed in terms of background doping density. In yet another embodiment, the effect of background doping density is removed by calculating intensity ratios of two PL measurements obtained in different spectral regions, or generated by different excitation wavelengths. The methods are particularly useful for bulk samples such as bricks or ingots of silicon, where information can be obtained over a much wider range of bulk lifetime values than is possible with thin, surface-limited samples such as silicon wafers. The methods may find application in solar cell manufacturing for improving the manufacture of silicon ingots and bricks, or for providing a cutting guide for wafering.

Disclosed is a method () of manufacturing at least one semiconductor photovoltaic cell or module and for classifying semiconductor material. In one implementation () the method involves luminescence imaging a wafer at each of a plurality of stages (-) of the manufacturing process, and comparing at least two images obtained from the imaging step in respect of the same wafer to identify the incidence or growth of a manufacturing process induced fault. The wafer is removed (-) from the manufacturing process () where a process induced fault is identified that exceeds a predetermined level of acceptability or the fault may be remedied, or the wafer passed to an alternate manufacturing process to match its characteristics. In an alternate implementation the method comprises classifying semiconductor material. For example, providing at least two wafers, obtaining luminescence images of each wafer comparing the images to determine the electrical structure similarity of the wafers, and grouping wafers with a predetermined level of electrical structure similarity into the same family. The inventive method is suitable for determining various forms of mechanical, electrical and cosmetic irregularities.

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Coogee, Australia

Thorsten Trupke