Gate Contact Isolation via Dual-Portion Dielectric Spacer
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Solution Overview
Problem
Existing semiconductor devices face challenges in forming gate contacts over active areas without shorting with source/drain contacts, particularly due to deep recesses that complicate via contact alignment and increase the risk of electrical shorts.
Innovation Solution
The implementation of semiconductor devices with shallow source/drain contacts and dielectric spacers with two portions to isolate the gate contact from the source/drain contacts, allowing for easier alignment and preventing shorting by creating a gap between the gate and source/drain contacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If gate contact is formed over active area to increase integration density, then integration density is improved, but risk of shorting with source/drain contact increases
Solution Approach 1:
A dielectric spacer is introduced as an intermediary element between the gate contact and source/drain contact. The spacer is formed by depositing dielectric material conformally over the gate structure and then performing anisotropic etching to create a recessed region filled with dielectric material, resulting in a protruding spacer that physically separates the gate contact from the source/drain contact, thereby preventing electrical shorting while allowing the gate contact to be positioned over the active area.
2Reliability
If deep recess is formed to prevent shorting between gate contact and source/drain contact, then shorting risk is reduced, but via contact alignment difficulty increases
Solution Approach 1:
The dielectric spacer is formed in advance before forming the source/drain contact and via contact. By pre-forming the spacer that protrudes from the gate structure, the alignment reference for subsequent via contact formation is established early in the process, simplifying the alignment procedure rather than requiring deep recesses to be formed after all other structures are in place.
3Manufacturing precision
If gate contact is positioned over active area, then device scaling is reduced, but alignment precision with source/drain contact becomes more difficult
Solution Approach 1:
The gate structure itself serves as the template for forming the dielectric spacer. The spacer is formed by depositing dielectric material conformally over the gate and then anisotropically etching to create a recess, which automatically positions the spacer relative to the gate contact. This self-aligned approach eliminates the need for separate alignment steps between the gate contact and source/drain contact, thereby maintaining manufacturing precision while enabling device scaling.
Data Source
AI summary
A method of making a semiconductor device includes patterning a fin in a substrate; forming a gate between source/drain regions over the substrate, the gate having a dielectric spacer along a sidewall; removing a portion of the dielectric spacer and filling with a metal oxide to form a spacer having a first spacer portion and a second spacer portion; forming a source/drain contact over at least one of the source/drain regions; recessing the source/drain contact and forming a via contact over the source/drain contact; and forming a gate contact over the gate, the gate contact having a first gate contact portion contacting the gate and a second gate contact portion positioned over the first gate contact portion; wherein the first spacer portion isolates the first gate contact portion from the source/drain contact, and the second spacer portion isolates the second gate contact portion from the source/drain contact.