Gate Contact Structure Above Active Region for Semiconductor Devices
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Solution Overview
Problem
In integrated circuits, the conventional method of forming gate contact structures above the isolation region leads to space inefficiency and potential electrical shorts, as the gate contact is not positioned directly above the active region, necessitating a method to conserve space and prevent shorts.
Innovation Solution
The method involves forming a sacrificial S/D contact structure above the S/D region, removing parts of the gate cap and sidewall spacer to create a gate contact cavity entirely above the active region, and then forming internal sidewall spacers within this cavity, allowing for the creation of conductively coupled gate and S/D contact structures without electrical shorts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the gate contact structure is formed above the isolation region using conventional methods, then the manufacturing process is simpler, but the chip area utilization is reduced and electrical shorts may occur
Solution Approach 1:
The gate contact cavity is positioned entirely above the active region in the vertical dimension, allowing the gate contact structure to be formed without lateral expansion into isolation regions. This vertical positioning strategy enables better space utilization on the chip plane while maintaining manufacturing feasibility through selective etching and filling processes.
2Area of stationary object
If the gate contact structure is positioned above the active region, then space is conserved and packing density increases, but electrical isolation between gate and S/D contacts becomes more difficult
Solution Approach 1:
The contact structure is segmented into distinct gate contact and S/D contact portions, separated by an internal sidewall spacer formed within the gate contact cavity. This segmentation allows both contacts to be positioned above the active region while maintaining electrical isolation through the spacer, preventing shorts while conserving chip area.
Solution Approach 2:
An internal sidewall spacer is introduced as an intermediary element within the gate contact cavity, positioned between the gate contact structure and the S/D contact structure. This spacer acts as an electrical isolator, enabling both contacts to coexist above the active region without electrical interference.
3Reliability
If the gate contact cavity is positioned entirely above the active region, then internal sidewall spacers can be formed for isolation, but the manufacturing process becomes more complex
Solution Approach 1:
The internal sidewall spacer is formed preliminarily within the gate contact cavity before the final gate contact and S/D contact structures are deposited. This preliminary action establishes the electrical isolation framework in advance, simplifying subsequent processing steps and reducing overall manufacturing complexity despite the advanced cavity positioning.
Data Source
AI summary
One illustrative method disclosed includes, among other things, forming a sacrificial S/D contact structure above an S/D region of a transistor device, removing at least a portion of a gate cap and at least a portion of a gate sidewall spacer to define a gate contact cavity that is positioned entirely above the active region and exposes an upper surface of a gate structure of the transistor device, and forming an internal sidewall spacer within the gate contact cavity. The method also includes performing at least one process operation to remove at least the sacrificial S/D contact structure and define a S/D contact cavity, and forming a gate contact structure within the gate contact cavity that is conductively coupled to the gate structure and forming a S/D contact structure within the S/D contact cavity that is conductively coupled to the S/D region.