Ensure consistent high product quality and maximum efficiency of solar cells and modules by using Op-tection products

OSIS Photovoltaic Products
A comprehensive metrology family that covers all critical process steps of c-Si PV manufacturing Our product family OSIS, or - Op-tection Solar Inspection Systems - is available to inspect every process step, from wafer to ready module. All machines are designed and optimized to measure inline. In addition, efficient and precise stand-alone machines are available as well, for offline testing and R&D work. The following overview lists the c-Si PV process steps that OSIS metrology systems can be applied to

Process Step: Incoming Wafers
OSIS Wafer-PL-Sorter: Sorting of as-cut wafers based on forecasted cell efficiency using Photo Luminescence imaging OSIS Wafer-Micro-Crack: inline inspection system for solar wafers to find micro-cracks, inclusions and to quantify grain properties OSIS Wafer-Thickness: inline thickness measurement system for wafers applied before saw damage removal

OSIS Wafer-PL-Sorter Sorting of as-cut wafers based on forecasted cell efficiency using Photo Luminescence imaging What if you could verify the potential of your as-cut wafers and avoid investing money in wafers that will become low efficient cells? Op-tection’s PL-based wafer sorters let you reliably verify the efficiency potential of as-cut wafers before you further process them to cells: Save money by rejecting and not further processing bad wafers Earn money by processing wafers with forecasted high efficiency accordingly

Fields of Application Our PL technology can be used for all types of solar wafers. The strongest benefit of this capability however applies to: Poly-Wafers: dislocation clusters, edge contamination fractions and corner brick metrics are weighted and used for a precise forecast. Pseudo-Mono-Wafers: this new generation of wafer material has some distinct characteristics that require detailed investigation and efficiency forecasting. The very small amount of grain boundaries make this type of wafer look nearly like a single crystal from the outside. However, dislocations are present in this material, and unlike regular poly-wafers, there are just few grain boundaries. This can result in over-proportional growth/presence of dislocations in pseudo-mono material, which strongly impacts the achievable cell efficiency.	Photo Luminescence The wafer under test is illuminated with strong laser light source to excite the luminescence response of the silicon. A sensitive and high-resolution camera combined with adapted filters records the Photo Luminescence (PL) image. This 2D image is a measure for the spatially resolved carrier lifetime of the silicon.	Wafer Sorting Wafer Sorting The OSIS-Sorter-PL is a fully-automatic box to box as-cut wafer sorter. User defined sorting parameters based on forecasted efficiency allow binning in multiple classes: Reject bad, not processable wafers Separate high efficient / premium wafers to process them accordingly Regular processing for standard wafers The sorter is available in various configurations to match your production throughput.

OSIS Wafer-Micro-Crack: Inline and on-the-fly micro-crack and defect inspection of solar wafers

FACT: The production of solar cells with the highest efficiency starts with flawless wafers. Precise incoming inspection is a key step to select and use such premium wafers. OSIS Wafer distinguishes itself from other optical wafer inspection systems by offering essential and unique capabilities. Premium optical components used in a proprietary transmission optical setup enable detection of defects, such as micro-cracks in the bulk silicon. Furthermore the wafers can be inspected completely to the edge. As OSIS Wafer measures on-the-fly, high line speed and throughput are guaranteed.	OSIS Wafer is an ideal system to be integrated into the OSIS Sorting system. When configured as wafer sorter, the system is a great asset as incoming wafer inspection for cell producers.	The user software unites various useful functions. First of all a large image of the scanned wafer is displayed. When activated the software marks found cracks, inclusions and further defects with colored circles. Based on user-selected quality standards, the wafer becomes a quality category, which is used to create production statistics and yield calculations. The full size image is also accessible by the user for detailed analysis of defect cause(s).

OSIS Wafer Thickness Non-contact inline measurement of wafer thickness High solar cell efficiency requires good and consistent wafer texture quality. The material removal rate is an important parameter to control the texturing as well as saw damage removal.

Unlike differential weighing methods, OSIS Wafer Thickness enables exact measurement of the material removal rate, without the need of correlations or assumptions. Typically one sensor is installed before the SDR/Texturing process. A second sensor measures the wafer thickness directly after, resulting in the material removal rate as thickness difference.	100% inline measurement of the material removal allows accurate prediction of the chemical bath life time. This helps to use the baths more efficient and save on disposal costs. In addition, the amount of material removed correlates well to the wafer reflectivity that is measured with OSIS Texture. OSIS Wafer Thickness is a non-contact interferometric measurement, hence no additional wafer handling or contacting is needed. With its 100 Hz measurement rate, complete wafer profiles are available quickly.	The measurement itself work reliably on both mono- and poly-wafers. Faulty readings are impossible as the measurement signal is either present, or not at all. The "hit-rate" on both wafer types is >90% so that dense data for each wafer is collected. Presentation example: (left) Trend chart of wafer thickness after SDR with min/man/ave; (right) Thickness profile of an individual wafer

Process Step: Saw Damage Removal and Texturing

OSIS Texture Inline measurement of wafer reflectivity after saw damage removal / texturing for direct process control High solar cell efficiency requires good and consistent wafer texture quality. Random offline measurement, such as weighing before and after etching, is labor intensive and only reveals process drifts with a large time-delay.

OSIS Texture immediately shows the reflection drift, when for example, the concentration or temperature of the acid bath changes. This allows you to directly take counter measures, which results in consistent texture quality and low reflection for all wafers that you produce. It also enables for example more effective bath activation. On top of that labor for tedious offline measurements is eliminated. OSIS Wafer Thickness is an additional powerful instrument to measure the exact material removal and work well in tandem with OSIS Texture.	OSIS Texture consists of proprietary optical probe which is connected to a spectrometer system via fiber optic cables. The optical probe is optimized to precisely measure the reflected and scattered light from the textured surface of the wafer. In addition an integrated optical filter avoids disturbing ambient light from interfering with the measurement. The size of the optical probe is extremely small compared to for example integrating spheres. This enables convenient mounting between the feed rolls of a line track.	The operation software provides comprehensive reflectivity statistics and trends from wafer to wafer as well as the complete batch to enable immediate intervention in case of process drifts. As the software also has an automatic wafer detection function, no additional hardware or sensors to detect the wafer position have to be used. This makes retrofitting of the system in existing production lines very simple.

Process Step: Anti-Reflection Coating and Passivation
OSIS Coating: high resolution measurement of thickness and refractive index of SiNx for batch coating process control and R&D OSIS Coating-Inline: high resolution measurement of thickness and refractive index of SiNx for process ramp-up and control

OSIS Coating Fast and high resolution mapping of layer thickness and refractive index of silicon nitride (SiNx) anti-reflection coating OSIS Coating is a very fast and precise measurement system for layer thickness and refractive index distribution measurement of Silicon Nitride Anti-Reflection Coating. It measures directly on textured production wafers. Fast and accurate hardware in combination with self explanatory software, touch screen operation, and a fast loading mechanism allow unequaled speed and user comfort.

The stand-alone version of OSIS Coating +n perfectly complements its inline counterpart. Production wafers that need further investigation after the deposition process, are measured precisely and fast. Equally important, OSIS Coating enables you to research coating behavior in more detail within just a fraction of the time compared to conventional metrology tools.	Operation of OSIS Coating is very straight-forward and self explanatory. After just a very short time your the user is comfortable operating the system. Important in particular is the speed with which you have access to the measurement data: 1) load the wafer on the tray 2) select the scan resolution 3) start the scan 4) wafer is unloaded and storage of measurement result 5) print a report	In Fast Scan Mode, OSIS Coating +n provides you with a meaningful distribution map of 100x100 thickness measurements and 100 refractive index measurements in less than 10 seconds. Operating in High-Res Mode, you will obtain rich data, which unveils the detailed deposition topography of your silicon nitride coated wafers. In under one minute, distribution maps of 400x400 thickness measurements and 400 refractive index measurements are available

OSIS Coating Inline Fast and high resolution inline measurement of layer thickness and refractive index of silicon nitride (SiNx) anti-reflection coatin

Measurement directly on textured wafers helps to avoid preparation of special polished wafers. Apart from lower labor expenses, measuring directly on the real production wafers has an additional benefit: the indirect correlation between the measurement on polished reference wafers and the actual textured production wafers becomes obsolet	Higher line up-time is another important capability that is obtained. Access to thickness and refractive index trends of every produced wafer will enable you to make optimum use of your plasma or sputtering targets. After periodic coater cleaning and maintenance you will be able to reach your process window more quickly as the required control readings are available directly after the first coated wafer. On an annual basis, this time gain will allow you to produce considerably more wafers.	Full surface measurement of layer thickness at up to 100x20 points as well as refractive index measurement of up to 20 points on each wafer provide unequaled real-time information about the SiNx AR coating process Presentation example: Thickness and refractive index trend data for a single cell handled setup. Each wafer is also presented as 2D map incl. thickness histogram.

Process Step: Screen Printing
OSIS Cell-EL-ac: cell electro luminescence with automatic cell contacting mechanism that is used for random testing and small batch testing OSIS Cell-EL-mc: cell electro luminescence with manual cell contacting mechanism that is used for R&D and random testing OSIS Cell-Sorter: full automatic solar cell tester/sorter platform, with optical and electrical cell testing capabilities for testing of incoming cells in module factories

OSIS Cell ac Flexible stand-alone system for quick batch testing of solar cells using electro luminescence imaging. FACT: The performance of any solar module is depending on the weakest cell in the assembly. Wet-chemical processing, coating, and screen printing can cause strong tension, resulting in silicon bulk defects that are not visible on the outside of the cell. Even if the IV-test shows the efficiency is high enough right now, micro cracks, shunts and edge isolation imperfections have long-term effects and can cause a dead cell in your module over time. OSIS Cell utilizes electro luminescence imaging to perform the ultimate check of the cell's integrity. The OSIS Cell version with automatic contacting is available as stand-alone, table-top system for small batch testing. Cells are loaded onto a transport belt on one side of the system. Upon start of measurement the cell is transported automatically into the dark exposure chamber. The cells' busbars are gently contacted, after which voltage is applied. After recording the EL image the cell is transported to the other side of the system.	OSIS Cell mc Flexible stand-alone system for comfortable and quick testing of different solar cell types using electro luminescence imaging. FACT: The performance of any solar module is depending on the weakest cell in the assembly. Wet-chemical processing, coating, and screen printing can cause strong tension, resulting in silicon bulk defects that are not visible on the outside of the cell. Even if the IV-test shows the efficiency is high enough right now, micro cracks, shunts and edge isolation imperfections have long-term effects and can cause a dead cell in your module over time. OSIS Cell utilizes electro luminescence imaging to perform the ultimate check of the cell's integrity. The OSIS Cell version with automatic contacting is available as stand-alone, table-top system for small batch testing. Cells are loaded by hand into the systems' manual contacting frame. Upon start of measurement voltage is applied. After recording the EL image the cell is removed by hand.	OSIS Cell Sorter Full automatic solar cell tester/sorter platform, with optical and electrical cell testing capabilities The OSIS Cell Sorter platform is designed to allow solar module makers to verify the integrity of the solar cells before they are processed to modules. Such testing pays off quickly and can avoid unnecessary labor and production cost, as well as module warranty claims. The tester/sorter enables you to: Find cells with micro-cracks that will impact the module during tabbing, stringing and the lamination process Verify if the cells meet the specified (and paid) efficiency Re-bin the cells in smaller efficiency classes to avoid power losses in the module Find printing and cosmetical defects on the cells

Process Step: Lamination
OSIS Module-A: stand-alone inspection system for laminated solar modules, based on electro luminescence imaging OSIS Module-C / -D: stand-alone inspection system for laminated solar modules, based on electro luminescence imaging OSIS Module-F: Electro Luminescence inspection system for solar modules for integration in a module flasher tunnel or a darkroom

OSIS Module A Stand-alone inspection system for laminated solar modules, based on electro luminescence imaging Uniting over 50 cells into one solar module is without any doubt the production step with most value at stake because a single faulty cell or a processing error can jeopardize the complete module. Electro luminescence is a powerful and reliable way to verify the integrity of your solar modules during production and before entering the market. The OSIS Module A inspection system is used after lamination of the module and is very valuable to inspect those modules that for example were classified as a low quality grade by the IV-tester. The EL image of the complete module and of individual cells, will enable you to pinpoint the cause of low quality and take countermeasures.	OSIS Module-C / -D Stand-alone dual camera inspection system for laminated solar modules, based on electro luminescence imaging. Uniting over 50 cells into one solar module is without any doubt the production step with most value at stake because a single faulty cell or a processing error can jeopardize the complete module. Electro luminescence is a powerful and reliable way to verify the integrity of your solar modules during production and before entering the market. The OSIS Module C inspection system is used after lamination of the module and is very valuable to inspect those modules that for example were classified as a low quality grade by the IV-tester. The EL image of the complete module and of individual cells, will enable you to pinpoint the cause of low quality and take countermeasures.	OSIS Module-F (Flasher) Electro Luminescence inspection system for solar modules for integration in a module flasher tunnel or a darkroom The OSIS-Module-F is an electro luminescence inspection system that inspects solar modules inside a module flasher or a dark room. The system automatically searches for module defect(s), such as dark areas and low efficiency areas in the cells of the module. Depending on the selected camera resolution, cracks in the cells are detected as well. The system is particularly useful as “last check” of the module integrity in the downstream of the module line.


Process Step: Lay-up / Matrix

		OSIS Module I Inline electro luminescence imaging system for fully automatic inspection of solar modules before and after Lamination. Uniting over 50 cells into one solar module is without any doubt the production step with most value at stake because a single faulty cell or a processing error can jeopardize the complete module. Electro luminescence is a powerful and reliable way to verify the integrity of your solar modules during production and before entering the market. OSIS Module I inspects all your modules inline. The pass-line height is adjustable to as low as 1 meter. In addition the inspection can be performed sunny-side down. This allows inspection of modules before lamination and avoids unnecessary handling steps for module flipping of laminated modules. The OSIS Module I system is integrated into the production line. Solar modules are loaded with the sunny side down into the EL inspection system. The internal system conveyor takes over the module from the conveyor of the production line while the input slit is opened. The module is now contacted to the integrated power supply by electrically driven contact fingers to allow gentle connecting. Alternatively the operator can also choose to manually connect modules with an assembled junction box by using a standard connector. Both contact mechanisms are electrically parallel, so either of both can be used depending on the required measurement.

Process Step: Doping and Diffusion

		OSIS Dopant Quick, accurate and consistent inline control of the phosphoric acid weight for each wafer Conventionally tight control of the phosphoric acid layer before diffusion is time consuming and tedious. Furthermore, manual weighing of the wafer can only be performed randomly. 100% inline measurement of the H3PO4 layer weight enables you to run a tighter process window. At the same time you can more efficiently use your operator resources. Dense data for the doper process enables you to operate in a smaller process window, hence more consistent PSG removal and more consistent sheet resistance can be achieved. H3PO4 weight is measured optically and contact-less. The phosphoric acid weight is displayed per wafer and as a trend chart for the entire batch.

Process Step: Tabbing & Stringing

		OSIS String Electro luminescence imaging system for fully automatic stand-alone and inline inspection of strings. Uniting over 50 cells into one solar module is without any doubt the production step with most value at stake because a single faulty cell or a processing error can jeopardize the complete module. Electro luminescence is a powerful and reliable way to verify the integrity of your solar modules before lamination The OSIS String inspection system is there to inspect your solar cells after tabbing and stringing but before putting together the matrix. This enables you to reliably find and re-work defects such as cracks, cell breakage, front grid defects, dark areas and contacting problems. The images that the system captures can be evaluated automatically by the software or alternatively by the system operator. The system reveals the integrity of the string before the lay-up takes place. Possible errors can be corrected without jeopardizing the module performance. The strings are loaded sunny side down onto the OSIS String systems. This can be done fully automatic with for example a robot or manually by an operator. After placement the system is closed to suppress ambient light and the string is automatically contacted to the power supply.

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