At advanced semiconductor nodes targeting sub-10 nm feature size, lithography starts to dominate costs, e.g. multiple mask passes per layer and edge placement errors. In order to overcome these limitations, techniques like area-selective deposition have gained increasing interest due to the inherent self-aligned fabrication scheme via control of the surface chemistry. However, investigations into other alternative techniques and materials are required to ensure continued 2D scaling and extension of Moore’s law.<br/>One promising technique is atomic precision advanced manufacturing (APAM), which enables exploration of unique device physics by producing devices doped beyond the solid solubility limit in a room temperature, surface activated process that is area-selective when used in conjunction with hydrogen lithography. Thus, APAM is appealing to augment complementary metal-oxide-semiconductor (CMOS) devices and sidestep scaling limits.<br/>The challenge to integrating APAM with CMOS is thermal – preparing the necessary atomically clean Si surface normally occurs above 850 °C, which would destroy many CMOS elements. This processing has only been demonstrated in ultra-high vacuum (UHV), which is limited by throughput and scalability. Solution or vapor phase-based chemistry, which is inherently scalable, provides a pathway towards overcoming both limitations.<br/>Herein, we investigate the surface chemical effects of hydrofluoric acid (vapor vs solution phase) on Si(100) using infrared and x-ray photoelectron spectroscopy to achieve a suitable surface termination. We demonstrate a suitably clean Si surface for APAM, prepared at less than 600 °C, that is compatible with the middle of a CMOS process flow.

Reduced temperature preparation of atomically clean Si surfaces to augment CMOS with atomic precision devices

ACS Spring Meeting 2021

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