Dopant Contamination refers to unintended introduction of electrically active impurities during semiconductor processing that alter device characteristics.

What Is Dopant Contamination?

• Sources: Cross-contamination from diffusion, ion implant, or handling
• Common Contaminants: Boron, phosphorus, arsenic from prior wafers
• Effect: Shifts threshold voltage, increases leakage, device failure
• Detection: SIMS, spreading resistance, electrical test

Why Dopant Contamination Matters

At sub-20nm nodes, even 10¹⁰ atoms/cm² of unwanted dopant significantly affects transistor characteristics, causing parametric failures.

<svg viewBox="0 0 452 245" xmlns="http://www.w3.org/2000/svg" style="max-width:100%;height:auto" role="img"><rect x="0" y="0" width="452" height="245" rx="12" fill="#0d1117"/><g font-family="ui-monospace,SFMono-Regular,Menlo,Consolas,&quot;Liberation Mono&quot;,monospace" font-size="14"><text xml:space="preserve" x="20" y="31.7"><tspan fill="#c9d1d9">Dopant Contamination Pathway:</tspan></text><text xml:space="preserve" x="20" y="50.7"><tspan fill="#c9d1d9">Process Chamber Wall:</tspan></text><text xml:space="preserve" x="20" y="69.7"><tspan fill="#6e7681">┌─────────────────────┐</tspan></text><text xml:space="preserve" x="20" y="88.7"><tspan fill="#6e7681">│</tspan><tspan fill="#c9d1d9"> ████ Prior wafer    </tspan><tspan fill="#6e7681">│</tspan></text><text xml:space="preserve" x="20" y="107.7"><tspan fill="#6e7681">│</tspan><tspan fill="#c9d1d9"> ████ residue        </tspan><tspan fill="#6e7681">│</tspan><tspan fill="#c9d1d9"> </tspan><tspan fill="#6e7681">←</tspan><tspan fill="#c9d1d9"> B, P, As deposits</tspan></text><text xml:space="preserve" x="20" y="126.7"><tspan fill="#6e7681">│</tspan><tspan fill="#c9d1d9">                     </tspan><tspan fill="#6e7681">│</tspan></text><text xml:space="preserve" x="20" y="145.7"><tspan fill="#6e7681">│</tspan><tspan fill="#c9d1d9">   New wafer         </tspan><tspan fill="#6e7681">│</tspan><tspan fill="#c9d1d9"> </tspan><tspan fill="#6e7681">←</tspan><tspan fill="#c9d1d9"> Contamination transfers</tspan></text><text xml:space="preserve" x="20" y="164.7"><tspan fill="#6e7681">│</tspan><tspan fill="#c9d1d9">   ●●●●●●●●●         </tspan><tspan fill="#6e7681">│</tspan></text><text xml:space="preserve" x="20" y="183.7"><tspan fill="#6e7681">└─────────────────────┘</tspan></text><text xml:space="preserve" x="20" y="202.7"></text><text xml:space="preserve" x="20" y="221.7"><tspan fill="#c9d1d9">Even ppb-level contamination affects Vt</tspan></text></g></svg>

Prevention Methods: