July 11, 2011 -- KLA-Tencor Corporation (NASDAQ:KLAC) launched a new generation in its Surfscan family of wafer defect and surface quality inspection systems: the Surfscan SP3. The unpatterned wafer inspection platform uses deep-ultraviolet (DUV) illumination and is extendible to 450mm wafers.
With Surfscan SP3, KLAC recognizes the need for substrate development and manufacture for ≤28nm devices. Defects such as crystalline pits, terracing, voids, etc., are problematic for current generation tools when applied at 28nm and below.
Amir Azordegan, senior director of marketing for Surfscan at KLA-Tencor, explains how the new DUV wafer inspection platform detects such defects at more advanced nodes. He also describes the significance of combining DUV illumination with special apertures, multiple illumination and collection channels. The new tool has a module that inspects the backside of wafers for defects that might deform the wafer shape during lithography.
 |
| Figure 1. Surfscan SP3 sensitivity at throughput. SOURCE: KLA-Tencor |
"From the standpoint of the user, the two key advances in the new platform are sensitivity and throughput," said Azordegan. "The new tool and its predecessors each have three or four operating points, and, predictably, sensitivity can be gained by operating the system at a lower throughput (Fig. 1). However, the SP3’s improved performance allows it to operate at SP2 or SP2XP sensitivity at significantly improved throughput [as indicated by the light blue and orange arrows]...sensitivity improvements allow it to detect smaller defects than its predecessors [Surfscan SP2 and SP2XP]," said Azordegan (Fig. 2). "However, the SP3 also introduces improved defect sizing capability for large defects -- those up to half a micron in size." With respect to sensitivity improvements, characterization of the defect population of a given size is one important means for binning and sorting wafers.
 |
| Figure 2. Surfscan SP3 dynamic range. SOURCE: KLA-Tencor |
With respect to bare wafer production sensitivity requirements (Fig. 3), Azordegan says that IC manufacturers want to detect defects as small as 25nm on typical prime silicon wafers, especially for wet clean, diffusion, CMP, and lithography modules. "Sensitivity requirements on bare wafers typically decrease by 25-30% per design node, because smaller and smaller defects affect device yield as the pattern shrinks," explained Azordegan. "One of the difficulties in making a more sensitive defect inspection system is that the signal required to detect such a small defect rises exponentially as the sensitivity specs tighten. The transition from the 3Xnm to the 2Xnm node has demanded a 700% increase in signal strength, one of the drivers for choosing a DUV source for the new platform."
 |
| Figure 3. Bare wafer production sensitivity requirements. SOURCE: KLA-Tencor |
The tool is extendible to 450mm wafers (Azodegan said that the company will supply a bridge tool first, and, within 12 months after receipt of order, the company will have a 450mm-dedicated tool).
The new system has been shipped to leading substrate and chip manufacturers in Asia, the United States, and Europe for use in advanced development and production lines.
Subscribe to Solid State Technology/Advanced Packaging.
Follow Solid State Technology on Twitter.com via editors Pete Singer, twitter.com/PetesTweetsPW and Debra Vogler, twitter.com/dvogler_PV_semi.