Sidewall Spacer Structure for Self-Aligned Contact Alignment

The gate electrode is divided into multiple segments along its length, with source/drain contacts formed at different locations relative to each segment. This segmentation allows the gate to maintain electrical connection with multiple contacts while preventing direct shorting between adjacent contacts, as each segment is electrically isolated from its neighbors by the insulating gate dielectric layer.

An insulating gate dielectric layer is introduced as an intermediary between the conductive gate electrode and the source/drain contacts. This dielectric layer prevents direct electrical contact (shorting) between the gate and contacts while still allowing the gate to exert control over the source/drain regions through electrical field effects, thus maintaining reliability while enabling close spacing.

The gate electrode and gate dielectric layer are formed beforehand, establishing precise registration marks and alignment references before the contact hole etch process. This preliminary formation of the gate structure provides fixed reference points that guide subsequent contact alignment, ensuring that even when contacts are formed at reduced distances, they remain properly positioned relative to the gate segments.

By dividing the gate into segments, the patent creates distinct registration zones for each contact. Each contact can be independently aligned to its corresponding gate segment, reducing the cumulative alignment errors that would affect a continuous gate structure. This segmentation approach allows for more tolerant manufacturing processes while maintaining the reduced unit cell dimensions.