The demand for higher yields in semiconductor manufacturing is driving the need for accurate, reliable wafer inspection systems to prevent the high costs that come from ruined wafers. However, higher-speed fabrication methods, along with more complex chip designs and nanometer-scale processes, can make finding defects and ensuring proper wafer placement increasingly difficult. Although cutting-edge optical and x-ray components are invaluable in addressing these wafer inspection challenges, they are only as good as your tool’s ability to place them with extreme precision at high speeds.

Recently, a leading manufacturer of wafer defect inspection and metrology equipment sought a positioning stage to manipulate optical and x-ray components inside a new system. The optical system measures register marks on wafers in order to stack them inside the system with perfect alignment. The optics inspect the wafers for critical dimensions and film thickness and also spot potentially damaging defects before the deposition and etching processes.

Due to the high speeds and extremely small dimensions and tolerances, selecting the right positioning table proved difficult for this application. Fortunately, the IKO NT55V positioning table was up to the challenge.

About the IKO NT55V Positioning Table
This table provided the inspection system manufacturer with positioning accuracy in a compact size. It has a width of 55 inches and 14-inch sectional height with a choice of stroke lengths of 25 or 65 millimeters to fit the system’s limited space. The table also features a built-in direct drive linear motor, high-strength neodymium magnets for the slide table and a high-resolution optical linear encoder scale mounted to the slide table, delivering exceptional accuracy.

For additional accuracy, the table incorporates an IKO Linear Way L non-recirculating type miniature linear motion rolling guide. All of the guide’s rolling elements contact both the raceways at all times, ensuring precise motion with minimal positioning variation.

Other highlights of the NT55V include:

• 0.5 or 0.1 µm resolution, depending on the speed requirement.
• ±0.5 um positioning repeatability.
• Speeds up to 1,300 mm/sec.
• 5 kg maximum load mass.
• Zero backlash.

The NT55V’s optical linear encoder scale requires no cables to connect the moving table to the bed, and its mechanical contact portion uses only a linear way. These two factors minimize mechanical movements that can otherwise generate particles in the clean environment. The table also exhibits low outgassing characteristics.

Our sales and support teams worked closely with the customer throughout the specification and purchasing process to ensure the table meets the requirements, attending meetings and answering all questions as needed.

Today, the NT55V is delivering trouble-free performance in the field, with no requests for changes or modifications. In fact, the company is considering two IKO linear components for a redesign of this successful inspection tool.

Precise Positioning Helps Fabricators Meet Aggressive Productivity Goals
Semiconductor fabricators demand higher-resolution scanning capabilities from wafer inspection systems, but the effectiveness of these tools depends on the accuracy and speed of the mechatronics that position the optical components inside the tools. This successful application demonstrates how our NT55V positioning stages offer a powerful combination of high precision, speed and performance, enabling fabricators to meet aggressive yield and efficiency targets.

For more information about IKO NT Series positioning tables, visit our product page.