MST Fundamentals

Quantum-engineered epitaxial silicon: a few atomic layers that change how dopants and defects behave.

What MST is

Quantum-engineered epitaxial silicon

A few nanometers of MST, grown in epitaxial silicon, with unique partial monolayers of elements that control where dopants go and how the surrounding silicon behaves through downstream thermal processing.

Each MST film in terms of the partial monolayer concentration, the numbers of layers is custom-engineered for its application.

See what MST does

TEM cross-section: MST epitaxial silicon on silicon

Interactive model

Explore the MST crystal

How MST blocks diffusion

Oxygen layers that hold dopants and defects in place

This is what lets MST engineer doping profiles no other film can: it removes the main mechanism dopants use to diffuse.

A local perturbation

A partial monolayer of oxygen inserted into the silicon lattice perturbs it locally, as seen directly in STEM.

Charge transfer

Oxygen pulls charge from the silicon atoms next to it; two layers away the lattice is ordinary silicon again.

Lower formation enthalpy

Vacancies, interstitials and substitutional dopants are more stable near the layer, so they are trapped there instead of moving through.

STEM image of silicon with an MST layer between the dashed lines, where the atomic columns shift, beside the matching atomic model with oxygen atoms in red

Seen directly in STEM

The MST layer perturbs the silicon lattice locally

Left: scanning transmission electron microscope image; between the dashed lines the atomic columns shift (yellow) where the partial oxygen monolayer sits. Right: the matching atomic model, oxygen in red. Above and below, the lattice is ordinary silicon.

The local perturbation is validation of the atomistic model

STEM courtesy of Prof. G. Balakrishnan and M. Frost, University of New Mexico.

Atomistic model of an MST oxygen layer in the silicon lattice, with silicon sites labelled 1A, 1B, 2, 3, 4A, 4B by distance from the oxygen — Atomistic model: an MST oxygen layer (O) in the silicon lattice

Charge transfer near the MST layer

Atom	Layer / site	Site charge
Oxygen	O	−1.01
Silicon	1A	+0.67
Silicon	1B	+0.51
Silicon	2	−0.07
Silicon	3	−0.01
Silicon	4A	0.00
Silicon	4B	0.00

The charge shift is confined to the first silicon layer next to the oxygen.

Formation enthalpy change of boron, phosphorus, vacancies and interstitials versus distance from the MST partial monolayer of oxygen — Formation enthalpy change near the MST layer

Learn more: whitepapers & publications

Manufacturing

Each MST film is custom-engineered for its application

Tool-independent

MST deposition is independent of tool supplier and chamber type.

Proven know-how

Perfected over hundreds of Silicon and Device wafer runs

Straightforward install

Existing reactors run MST with a simple upgrade.

Thermally stable

MST films have proven thermal stability.

Manufacturing Tools

Proven MST growth on EPI tool of all three vendors

MST has been grown in-situ in production proven epitaxial reactors from the major tool suppliers. The upgrade requires feeding MST precursor that is readily available from chemical suppliers.

Applied Materials

ASM

Kokusai Electric

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Evaluate MST in your own process and devices with Atomera's engineering team.