Inside Rudolph’s new inspection modules

by Debra Vogler, senior technical editor, Solid State Technology

Oct. 3, 2008 – Rudolph Technologies recently announced its third-generation E30 and B30 modules for wafer edge and backside inspection, equipped with performance enhancements needed for inspection and in-line monitoring of 32nm manufacturing processes from frontend-of-line (FEOL) through final manufacturing. First shipments are scheduled for 4Q08.

Tuan Le, product manager, inspection at Rudolph Technologies, told SST demand for the products was driven by the switch to immersion lithography at 45nm. Improvements in system optics enables the detection of edge defects as small as 2μm on patterned, production wafers. According to Le, the patent-pending SoftLens inspection technology images the entire wafer edge bevel region such that only the in-focus pixels are kept and their coordinates are preserved. “The images of the entire wafer edge region are then inspected together to provide improved capture rate and increased resolution,” Le explained. He also said that the new technology breaks the conventional tradeoff between depth-of-field and resolution, allowing for sensitivity over the complex curved surfaces of the bevel. On the backside, new optics improve backside defect sensitivity to 3μm.

Both the B30 and E30 modules use image-based inspection to provide a much richer data set than light scattering techniques enabling enhanced accuracy in sizing, locating, and classifying defects. The E30’s improved darkfield capability increases its sensitivity to 2μm, while its ability to suppress the signal from the pattern allows inspection of production wafers. The E30 module also provides metrology capability for the edge-bevel profile, multi-film edge bead removal and bevel clean processes.

Pairing the E30 and B30 tools “is a very popular combination,” noted Le. He added that, unlike the inspection of zone 1 (see figure below), where there are many other choices for examining the frontside, if a user needs to know more about the backside (zone 5), it’s more difficult because of the limited toolsets to look at its interior. “If you want to do this on a product wafer, you would have to flip it over onto an optical review or SEM station and you would destroy the product,” he said. “So the B30 allows you to inspect the zone 5 area and in addition, the interior of the wafer, so you have a bigger picture of what’s happening on the backside.”

When combined with the AXi 940 frontside module in Rudolph’s Explorer Inspection Cluster, the system provides immediate correlation between backside defects and frontside defectivity. A redesigned wafer handler reduces the possibility of handler-induced film delamination by avoiding contact with complex film stacks that may now extend into the upper bevel, and onboard computing power has been increased to support future releases of more capable algorithms.

On a patterned wafer, the Rudolph E30/B30 Inspection Module can inspect for defects from wafer edge zone 1 through 5 and the entire wafer backside.


Easily post a comment below using your Linkedin, Twitter, Google or Facebook account. Comments won't automatically be posted to your social media accounts unless you select to share.