Multi-Layer Gate ILD Structure to Prevent Contact Metal Bridging
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Solution Overview
Problem
The scaling down of semiconductor IC dimensions leads to increased complexity in manufacturing, particularly due to metal contact bridges and insufficient etching selectivity in single-layer interlayer dielectric (ILD) structures, resulting in poor device performance and reduced device life.
Innovation Solution
A three-layer interlayer dielectric (ILD) structure is introduced, providing enhanced etching selectivity and preventing metal bridges by using distinct materials for each layer, thereby improving contact reliability and extending device life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If single-layer interlayer dielectric (ILD) structure is used, then manufacturing process is simpler, but etching selectivity is insufficient leading to metal contact bridges
Solution Approach 1:
The single-layer ILD structure is segmented into three distinct layers (first ILD layer, second ILD layer, and third ILD layer) with different materials and etching rates. This segmentation provides progressive etching selectivity, allowing precise control during contact hole formation while preventing metal contact bridges between adjacent contacts.
Solution Approach 2:
The patent employs composite materials by combining three different dielectric materials (e.g., silicon oxide, silicon nitride, silicon oxynitride) in a stacked configuration. Each material is selected for its specific etching characteristics, creating a composite structure that achieves superior etching selectivity and contact reliability.
2Productivity
If IC dimensions are scaled down, then production efficiency improves and costs decrease, but distance between contacts decreases leading to metal contact bridges
Solution Approach 1:
The three-layer ILD structure segments the dielectric region into distinct functional layers, each contributing to contact isolation and etching control. This segmentation maintains reliable contact formation even as contact pitch decreases due to IC scaling, preventing metal bridge formation while preserving production efficiency.
Solution Approach 2:
Each ILD layer is assigned specific local properties (different etching rates, different materials) to address local requirements at the contact region. The first ILD layer provides base isolation, the second layer enhances selectivity, and the third layer optimizes contact hole etching, ensuring contact reliability during scaling.
3Device complexity
If single-layer ILD is used, then device structure is simpler, but TDDB window is reduced shortening device life
Solution Approach 1:
The ILD structure is segmented into three layers with progressively optimized properties, where each layer contributes to extending the TDDB window. The differentiated material composition and thickness of each layer create enhanced electrical isolation and stress distribution, thereby extending device operational life despite increased structural complexity.
Solution Approach 2:
The composite three-layer ILD structure uses materials with complementary properties to enhance device reliability. The combination of different dielectric materials provides superior electrical isolation and mechanical properties, extending the time-dependent dielectric breakdown window and thus device lifespan.
Data Source
AI summary
Semiconductor device and the manufacturing method thereof are disclosed herein. An exemplary semiconductor device comprises a fin disposed over a substrate, a gate structure disposed over a channel region of the fin, such that the gate structure traverses source/drain regions of the fin, a device-level interlayer dielectric (ILD) layer of a multi-layer interconnect structure disposed over the substrate, wherein the device-level ILD layer includes a first dielectric layer, a second dielectric layer disposed over the first dielectric layer, and a third dielectric layer disposed over the second dielectric layer, wherein a material of the third dielectric layer is different than a material of the second dielectric layer and a material of the first dielectric layer. The semiconductor device further comprises a gate contact to the gate structure disposed in the device-level ILD layer and a source/drain contact to the source/drain regions disposed in the device-level ILD layer.