Quality Magazine

Case Study: Optical Microscope Keeps Up with Production Needs

December 8, 2011
Custom production interface helps solve a critical cavity depth process control metrology problem.

Sample preparation time takes approximately 1 minute set up and measure with the GT-X3. Source: Bruker Nano Surfaces Division


As production manufacturing tolerances are pushed to tighter limits, accurate metrology becomes critical to product success. ON Semiconductor (Phoenix), a leading electronics manufacturer, has chosen the Bruker (Tucson, AZ) ContourGT-X3 3-D Optical Microscope to support its copper wire bond pad inspection and process control needs. The production-level speed of the ContourGT-X3 combined with the ease of use and custom production interface has enabled ON Semiconductor to solve a critical cavity depth process control metrology problem, according to Harold Anderson, principal staff engineer at ON Semiconductor.



Cavity Depth in Wire Bonding

In the copper wire bonding process, high forces are used to bond the wire to bond pads. A cavity depth optimization problem results-too much or too little force means reduced reliability of the final wire bond. Therefore, an accurate and fast method for quantifying the cavity depth is necessary. The need for fast, automated inspection with excellent vertical resolution over a relatively large field of view makes 3-D microscopy based on white light interferometry an excellent choice for this application.

To address this problem, ON Semiconductor chose the Bruker ContourGT-X3 3-D Optical Microscope. Their selection was based on the need for a system that offered a combination of automated run-time metrology, robust analysis and ease of use of the operator interface for industrial applications.

Additionally, automated logging of pass/fail criteria on hundreds of defined parameters of measurement can be set and stored to a part-specific database for sorting and part rejection, while eliminating operator bias and variance. A line engineer or manager can create specific material recipes which are automatically linked to material via operator ID, material ID, or lot/inspection ID.

Compared to SEM inspection, sample preparation time is reduced from 15 to 20 minutes to approximately a minute set up and measure with the GT-X3, says Anderson.

These software controls smooth the transition process control to production and allow for accurate identification and flagging of good and bad production output.

The ContourGT-X3 system is ideal for keeping up with production environment needs with stable metrology and analysis for a multitude of applications. These key features make the GT-X3 an excellent choice where 24/7 shift operation is employed for production inspection and process control.



Bruker Nano Surfaces Division

(520) 741-1044

www.bruker-axs.com

Benefits

Sample preparation time is reduced from 15 to 20 minutes to approximately a minute with the GT-X3.

Automated logging of pass/fail criteria on hundreds of defined parameters of measurement can be set and stored to a part-specific database for sorting and part rejection.

Software controls smooth the transition process control to production and allow for accurate identification and flagging of good and bad production output.