Charged Particle Beam Focus Adjustment via Reduced Emission Current

The patent applies preliminary action by performing focus adjustment and centering adjustment at a reduced emission current (first adjustment value) before increasing to the target emission current. This preliminary adjustment at lower current prevents excessive heating and damage to the aperture substrate while still achieving the necessary alignment. The adjustment is then finalized at the target current without requiring repeated scanning that would cause damage.

The patent changes the emission current parameter during the adjustment process. It uses a first adjustment value (lower than target) during the scanning adjustment phase to minimize substrate damage, then transitions to a second adjustment value (target value) for actual drawing operations. This parameter change allows the system to balance adjustment effectiveness with substrate protection.

The patent performs preliminary focus and centering adjustment at the reduced emission current before finalizing at the target current. This preliminary action at lower current establishes a baseline alignment that remains valid even when the current is increased, reducing the need for repeated adjustments and minimizing both substrate damage and total adjustment time.

The patent maintains continuity of useful action by performing the adjustment process in a continuous sequence: first adjusting at reduced current, then increasing to target current, and completing the adjustment without interruption. This continuous approach prevents the need to return to adjustment mode due to drift, as the initial adjustment remains valid across the current transition.

The patent performs the focus adjustment and centering adjustment as preliminary actions at a reduced emission current before increasing to the target current for production. This preliminary adjustment at lower current achieves the necessary measurement precision for alignment while significantly reducing the heating and erosion that would occur if the same scanning were performed at target current, thereby extending aperture substrate lifespan.

The patent changes the emission current parameter from a first adjustment value (lower than target) during the adjustment scanning phase to a second adjustment value (target value) for actual drawing. This parameter change enables precise focus and centering adjustment while minimizing thermal damage to the aperture substrate, resolving the contradiction between measurement precision and substrate durability.