Process variability of self-aligned multiple patterning

Sustainability and applicability of spacer-related patterning towards 7nm node

“…For those reasons, we mention again the full inversion scheme that we have been proposing for a number of years. [4] The first benefit is achievement of exactly the same stable line cut process as for the Fin and Gate layers. Line cuts are made at the parts to be blocked and then gap-filling is performed for the spin-on or the ALD and CVD process.…”

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Self-aligned multiple patterning technique has enabled the further down scaling through 193 immersion lithography extension [1][2][3][4][5]. In particular, focus on the logic device scaling, we have finished the verification of patterning technology of up to 10nm node [6-7], we will discuss about some patterning technologies that are required to 7nm node.

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Opportunities and Challenges in Scaling

“…This pitch-narrowing technique should, in theory, be able to scale down feature size indefinitely by repeating the same process. As shown in Figure 4, process demonstrations have shown that the SADP technique can be used to achieve up to 1/8 pitch narrowing (SAOP: pitch octupling), which means that scaling as far as the sub-10 nm region is realistically possible [3]. [5].…”

“…To resolve this issue, we proposed the "grid & trim" technique that first forms a hole pattern of equal pitch on the grid lines and then forms an upper-layer pattern that partially obscures the dense hole pattern. This upper-layer mask pattern opens up only that portion of the hole pattern needed for line cutting ( Figure 13) [8]. The biggest advantage of this process method is that it dramatically eases the requirements for overlay accuracy compared to using the above LELE technique.…”

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One of the most promising techniques for the extension of 193nm immersion lithography must be Self-Aligned Multiple Patterning (SAMP) [1,2,3] at present. We have studied this SAMP from several aspects, which are scaling capability, mitigation of process complexity, pattern fidelity, affordability and so on.

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