Ion Implantation Implant Completion
# Implant Completion and In-Situ Analysis: Step 7 — End-of-Implant Verification
The implantation process completes when the target dose is reached. Step 7 marks the transition from active implantation to post-implant processing. At this point, the ion beam is turned off, and the wafer is held at its controlled temperature for a few seconds to allow any residual temperature transients to settle. Dopants have been incorporated into the wafer to a depth determined by their implantation energy (typically 0.1–1 micrometer), but they are not yet electrically active — they occupy interstitial sites or defect-decorated lattice sites rather than substitutional positions. The dopants will become active only after thermal annealing (covered in Steps 8–25). Step 7 performs end-of-implant verification — checking that the target dose was indeed delivered, measuring any residual beam current to ensure shutdown, and preparing the wafer for removal and annealing.
## 1. Residual Damage and Amorphization
As ions are implanted, they create lattice damage: vacancies, dislocations, and in high-dose regions, complete amorphization (loss of crystalline order). The depth of amorphization depends on implantation energy and dose. A light 30 keV boron implant at 10¹⁴ B/cm² creates minimal damage (a few hundred angstroms of disorder). A heavy 500 keV arsenic implant at 10¹⁶ As/cm² creates deep, severe damage or even a thin amorphous layer. This damage must be repaired by thermal annealing; without annealing, the device is non-functional (high leakage, no conductivity). Step 7 does not anneal (that is Steps 8 and beyond) but documents the initial implant condition for later annealing planning.
## 2. Real Diagram: Implant Profile and Damage Distribution
## 3. Implant State Characterization
Advanced implanters include secondary ion mass spectrometry (SIMS) or other analytical tools to verify the implanted dopant profile immediately post-implantation. This feedback ensures that the planned profile matches the delivered profile. If deviations are detected (e.g., shallower-than-expected profile due to sputtering), the implantation recipe can be corrected for subsequent wafers.
## 4. Real Diagram: Residual Damage and Amorphization
## Implant Completion's Place in the Process Lineage
Implant completion is step 7 of the ion implantation series — marking the end of the high-energy dopant injection phase. Step 8 covers wafer removal and sample transfer. Steps 9–25 cover thermal annealing, damage recovery, and dopant activation.