Spike Rta Millisecond Laser Rta Flash Lamp

Every anneal faces the same fight: enough thermal budget to activate dopant, but as little time at high temperature as possible to avoid diffusing it wider than intended. Spike RTA and millisecond annealing are two successive answers to that fight — each one shrinking the "time at peak temperature" term closer to zero.

Spike RTA is a lamp-heated anneal engineered to have essentially no soak time at all — the wafer ramps to peak temperature (often 1000–1100°C) as fast as the lamp bank physically allows, then ramps back down immediately, spending only a second or two anywhere near peak. That's enough time for dopant to fully activate electrically, because activation kinetics are fast, while drastically limiting diffusion, because diffusion depends on both temperature *and* time — cutting the time term to nearly zero caps how far dopant can spread even at a high peak temperature.

Millisecond annealing pushes the same idea to its physical limit. A scanning laser or a flash lamp delivers enough energy to bring just the near-surface region to very high temperature — sometimes approaching silicon's melting point — for a duration measured in milliseconds rather than seconds, while the bulk wafer underneath stays comparatively cool. That extreme, localized, non-equilibrium heating can activate dopant concentrations *above* what a conventional furnace anneal's solid solubility limit would otherwise allow, because the process happens too fast for the system to settle into its normal equilibrium behavior.

This progression — furnace → spike RTA → millisecond anneal — tracks directly with shrinking junction depths. Ultra-shallow source/drain extensions in modern transistors need abrupt, well-activated dopant profiles only a few nanometers deep; a conventional furnace anneal would diffuse that profile into irrelevance before it ever reached its target depth. Each successive anneal technology exists specifically to keep activating dopant without undoing the sharp, shallow profile the implant itself was engineered to create.