Backside Power Rail Contact Layout for High-Aspect-Ratio Filling
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Solution Overview
Problem
The formation of high aspect ratio contacts in integrated circuit devices leads to defects such as narrow openings and incomplete filling, resulting in poor electrical connections and increased resistance, which complicates the middle-of-line (MOL) and back-end-of-line (BEOL) fabrication processes.
Innovation Solution
The formation of two separate contacts with lower aspect ratios, each connected to form a single contact, and the use of a single etch stop layer to reduce defects and parasitic capacitance, simplifying the fabrication process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single high aspect ratio contact is formed to connect frontside and backside elements, then electrical connection is achieved, but defects such as narrow openings and incomplete filling occur, resulting in poor electrical connections and increased resistance
Solution Approach 1:
The patent divides a single high aspect ratio contact into multiple separate contacts with lower aspect ratios. Specifically, the contact structure is segmented into frontside contacts (first and second contacts) and backside contacts (third and fourth contacts), each having reduced aspect ratios that enable complete filling and defect-free formation, thereby improving manufacturing precision while maintaining reliable electrical connection through the combined conductive path
2Productivity
If a backside power rail is included to simplify BEOL fabrication, then integration density increases, but high aspect ratio contacts are required which introduce defects and complicate the process
Solution Approach 1:
The patent segments the contact structure into multiple lower aspect ratio contacts instead of using a single high aspect ratio contact, enabling reliable electrical connection while maintaining the simplified BEOL fabrication process with backside power rail
Solution Approach 2:
The patent utilizes the vertical dimension by forming contacts at different heights and positions (frontside contacts at first height, backside contacts at second height) to create multiple conduction paths, achieving both simplified fabrication and reliable electrical connection
3Manufacturing precision
If multiple etch stop layers are used in contact formation, then manufacturing control is improved, but device complexity and parasitic capacitance increase
Solution Approach 1:
The patent merges the functions of multiple etch stop layers into a single etch stop layer that serves the entire contact formation process for both frontside and backside contacts. This consolidation reduces device complexity and minimizes parasitic capacitance while maintaining sufficient manufacturing control through the unified etch stop structure
Data Source
AI summary
Methods of forming an integrated circuit devices may include providing first and second active regions, an isolation layer, and first and second sacrificial stack structures. The first and second sacrificial stack structures may contact the first and second active regions, and the first and second sacrificial stack structures may each include a channel layer and a sacrificial layer. The methods may also include forming an etch stop layer on the isolation layer, replacing portions of the first and second sacrificial stack structures with first and second source/drain regions, forming a front contact including a front contact plug, forming a back-side insulator, and forming a back contact plug in the isolation layer and the back-side insulator. At least one of a portion of the front contact plug and a portion of the back contact plug may be in the etch stop layer.