Midwest Research Institute

Alliance for Sustainable Energy, LLC

The United States of America As Represented by the United States

Ut-battelle, Inc.

The United States of America As Represented by United States Department

Bhushan L Sopori

Przemyslaw Rupnowski

Michael J Ulsh

Claus Daniel

Jianlin Li

David L Wood, Iii

Peter Sheldon

Michael Mihaylov Penev

Artak Hambarian

Guido Bender

Todd Marshall

Robert C Murphy

Craig Marshall

Larry C Allen

Anikara Rangappan

Abraham Wolf

Thermal methods and systems are described for the batch and/or continuous monitoring of films and/or membranes and/or electrodes produced in large-scale manufacturing lines. Some of the methods described include providing an energy input into a film, measuring a thermal response of the film, and correlating these to one or more physical properties and/or characteristics of the film.

Batch and continuous methods for evaluating the physical and thermal properties of films

A monitoring systemcomprising a material transport systemproviding for the transportation of a substantially planar materialthrough the monitoring zoneof the monitoring system. The systemalso includes a line camerapositioned to obtain multiple line images across a width of the materialas it is transported through the monitoring zone. The systemfurther includes an illumination sourceproviding for the illumination of the materialtransported through the monitoring zonesuch that light reflected in a direction normal to the substantially planar surface of the materialis detected by the line camera. A data processing systemis also provided in digital communication with the line camera. The data processing systemis configured to receive data output from the line cameraand further configured to calculate and provide substantially contemporaneous information relating to a quality parameter of the material. Also disclosed are methods of monitoring a quality parameter of a material.

On-line, continuous monitoring in solar cell and fuel cell manufacturing using spectral reflectance imaging

Systems and methods for semiconductor device PN junction fabrication are provided. In one embodiment, a method for fabricating an electrical device having a P-N junction comprises: depositing a layer of amorphous semiconductor material onto a crystalline semiconductor base, wherein the crystalline semiconductor base comprises a crystalline phase of a same semiconductor as the amorphous layer; and growing the layer of amorphous semiconductor material into a layer of crystalline semiconductor material that is epitaxially matched to the lattice structure of the crystalline semiconductor base by applying an optical energy that penetrates at least the amorphous semiconductor material.

Semiconductor device PN junction fabrication using optical processing of amorphous semiconductor material

An optical cavity furnacehaving multiple optical energy sourcesassociated with an optical cavityof the furnace. The multiple optical energy sourcesmay be lamps or other devices suitable for producing an appropriate level of optical energy. The optical cavity furnacemay also include one or more reflectorsand one or more wallsassociated with the optical energy sourcessuch that the reflectorsand wallsdefine the optical cavityThe wallsmay have any desired configuration or shape to enhance operation of the furnace as an optical cavityThe optical energy sourcesmay be positioned at any location with respect to the reflectorsand walls defining the optical cavity. The optical cavity furnacemay further include a semiconductor wafer transport systemfor transporting one or more semiconductor wafersthrough the optical cavity.

Optical cavity furnace for semiconductor wafer processing

Wafer breakage is a serious problem in the photovoltaic industry because a large fraction of wafers (between 5 and 10%) break during solar cell/module fabrication. The major cause of this excessive wafer breakage is that these wafers have residual microcracks&#x2014;microcracks that were not completely etched. Additional propensity for breakage is caused by texture etching and incomplete edge grinding. To eliminate the cost of processing the wafers that break, it is best to remove them prior to cell fabrication. Some attempts have been made to develop optical techniques to detect microcracks. Unfortunately, it is very difficult to detect microcracks that are embedded within the roughness/texture of the wafers. Furthermore, even if such detection is successful, it is not straightforward to relate them to wafer breakage. We believe that the best way to isolate the wafers with fatal microcracks is to apply a stress to wafers&#x2014;a stress that mimics the highest stress during cell/module processing. If a wafer survives this stress, it has a high probability of surviving without breakage during cell/module fabrication. Based on this, we have developed a high throughput, noncontact method for applying a predetermined stress to a wafer. The wafers are carried on a belt through a chamber that illuminates the wafer with an intense light of a predetermined intensity distribution that can be varied by changing the power to the light source. As the wafers move under the light source, each wafer undergoes a dynamic temperature profile that produces a preset elastic stress. If this stress exceeds the wafer strength, the wafer will break. The broken wafers are separated early, eliminating cost of processing into cell/module. We will describe details of the system and show comparison of breakage statistics with the breakage on a production line.

Wafer screening device and methods for wafer screening

Methods for contact formation and gettering of precipitated impurities by multiple firing during semiconductor device fabrication are provided. In one embodiment, a method for fabricating an electrical semiconductor device comprises: a first step that includes gettering of impurities from a semiconductor wafer and forming a backsurface field; and a second step that includes forming a front contact for the semiconductor wafer, wherein the second step is performed after completion of the first step.

Contact formation and gettering of precipitated impurities by multiple firing during semiconductor device fabrication

A method for screening silicon-based wafers used in the photovoltaic industry is provided herewith.

Screening of silicon wafers used in photovoltaics

Various exemplary methods () are directed to determining wafer thickness and/or wafer surface characteristics. An exemplary method () includes measuring reflectance of a wafer and comparing the measured reflectance to a calculated reflectance or a reflectance stored in a database. Another exemplary method () includes positioning a wafer on a reflecting support to extend a reflectance range. An exemplary device () has an input (), analysis modules (-) and optionally a database (). Various exemplary reflectometer chambers () include radiation sources positioned at a first altitudinal angle () and at a second altitudinal angle (). An exemplary method includes selecting radiation sources positioned at various altitudinal angles. An exemplary element () includes a first aperture () and a second aperture () that can transmit reflected radiation to a fiber and an imager, respectfully.

Wafer characteristics via reflectometry

Described herein is an optical probe () for use in characterizing surface defects in wafers, such as semiconductor wafers. The optical probe () detects laser light reflected from the surface () of the wafer () within various ranges of angles. Characteristics of defects in the surface () of the wafer () are determined based on the amount of reflected laser light detected in each of the ranges of angles. Additionally, a wafer characterization system () is described that includes the described optical probe ().

Optic probe for semiconductor characterization

An exemplary system includes a measuring device to acquire non-contact thickness measurements of a wafer and a laser beam to cut the wafer at a rate based at least in part on one or more thicknesses measurements. An exemplary method includes illuminating a substrate with radiation, measuring at least some radiation reflected from the substrate, determining one or more cutting parameters based at least in part on the measured radiation and cutting the substrate using the one or more cutting parameters. Various other exemplary methods, devices, systems, etc., are also disclosed.

Wafer characteristics via reflectometry and wafer processing apparatus and method

A method is provided for gettering impurities from silicon wafers and devices to improve the quality of the material and the device performance. The wafer or the device is coated on the back-side with a layer of aluminum and is illuminated form the other side with light having a significant portion of energy in the IR region. This process leads to formation of a Si&#x2014;Al melt on the backside, at temperature below 550&#xb0; C. Dissolved impurities in the Si diffuse toward the Al melt and are trapped there. At higher illuminations and concomitant higher temperatures, the Al interface serves as a source of point defect injection. This mode of processing causes dissolution of precipitated impurities at greatly reduced temperatures and in short periods of time.

Metal processing for impurity gettering in silicon

The invention provides an improved optical system for determining the physical characteristics of a solar cell. The system comprises a lamp means for projecting light in a wide solid-angle onto the surface of the cell; a chamber for receiving the light through an entrance port, the chamber having an interior light absorbing spherical surface, an exit port for receiving a beam of light reflected substantially normal to the cell, a cell support, and an lower aperture for releasing light into a light absorbing baffle; a means for dispersing the reflection into monochromatic components; a means for detecting an intensity of the components; and a means for reporting the determination.

Optical system for determining physical characteristics of a solar cell

A semiconductor device having a substrate, a conductive intermediate layer deposited onto said substrate, wherein the intermediate layer serves as a back electrode, an optical reflector, and an interface for impurity gettering, and a semiconductor layer deposited onto said intermediate layer, wherein the semiconductor layer has a grain size at least as large as the layer thickness, and preferably about ten times the layer thickness. The device is formed by depositing a metal layer on a substrate, depositing a semiconductive material on the metal-coated substrate to produce a composite structure, and then optically processing the composite structure by illuminating it with infrared electromagnetic radiation according to a unique time-energy profile that first produces pits in the backside surface of the semiconductor material, then produces a thin, highly reflective, low resistivity alloy layer over the entire area of the interface between the semiconductor material and the metal layer, and finally produces a grain-enhanced semiconductor layer. The time-energy profile includes increasing the energy to a first energy level to initiate pit formation and create the desired pit size and density, then ramping up to a second energy level in which the entire device is heated to produce an interfacial melt, and finally reducing the energy to a third energy level and holding for a period of time to allow enhancement in the grain size of the semiconductor layer.

High efficiency, low cost, thin film silicon solar cell design and method for making

High efficiency low cost thin film silicon solar cell design and method

A method and apparatus for measuring characteristics of a piece of material, typically semiconductor materials including photovoltaic devices. The characteristics may include dislocation defect density, grain boundaries, reflectance, external LBIC, internal LBIC, and minority carrier diffusion length. The apparatus includes a light source, an integrating sphere, and a detector communicating with a computer. The measurement or calculation of the characteristics is calibrated to provide accurate, absolute values. The calibration is performed by substituting a standard sample for the piece of material, the sample having a known quantity of one or more of the relevant characteristics. The quantity measured by the system of the relevant characteristic is compared to the known quantity and a calibration constant is created thereby.

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Denver, CO, United States of America

Bhushan L Sopori