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Centura® Integrated Gate Stack

In a high-k/metal gate transistor, the dielectric stack is composed of the interface oxide layer and the bulk high-k layer.

An introduction to the Centura Integrated Gate Stack system

With each node, the stack thickness must scale down to meet ever decreasing EOT targets to achieve desired device performance. Scaling to 22nm and below requires that ALD be used to achieve the ultra-thin layer of high-k film. To reduce the EOT further, plasma nitridation is employed to incorporate a controlled dose of nitrogen into the stack, followed by annealing to stabilize the incorporated nitrogen atoms.

The system consists of an ALD HfO2 (hafnium oxide) deposition chamber and specialized chambers for interface layer oxide formation, post high-k nitridation, and post-nitridation anneal.
Challenges in nanoscale transistor gate engineering

Integrating these chambers on a single cluster tool is essential for fabricating high-performance transistors at the 22nm and 14nm nodes. The dielectric gate stack is the core of the transistor and is electrically very sensitive to variation and quality. At each logic technology node reduction, the interface-to-bulk ratio increases dramatically, making elimination of queue time ever more crucial to avoid thickening of the interface layers. Also, during air breaks, molecular contaminants (e.g., C, N, O, F, S) can be incorporated into the gate stack interfaces. Integrating the process chambers onto a single vacuum mainframe is the surest way of minimizing these issues and ensuring repeatable, high-quality performance.