Multi-Layer Interlayer Dielectric Structure for Crack and Hydrogen Control
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Solution Overview
Problem
Conventional interlayer dielectric (ILD) structures in semiconductor devices, particularly in LTPO devices, suffer from yield loss due to cracking during cleaning processes and hydrogen diffusion issues, which affect the threshold voltage and overall device performance.
Innovation Solution
A multi-layer ILD structure is introduced, comprising a first dielectric layer with a high hydrogen concentration formed at a high deposition rate and a second dielectric layer with a low hydrogen concentration formed at a lower deposition rate, along with a passivation layer to prevent hydrogen diffusion, using materials like silicon oxide and silicon nitride.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional single-layer ILD structure is used, then the manufacturing process is simple, but yield loss occurs due to cracking during cleaning processes
Solution Approach 1:
The ILD structure is divided into multiple layers (first dielectric layer, second dielectric layer, and passivation layer) with different materials and properties. Each layer serves a specific function: the first dielectric layer provides insulation, the second dielectric layer prevents cracking, and the passivation layer protects against moisture and hydrogen diffusion. This segmentation resolves the contradiction by maintaining manufacturing feasibility while significantly improving device yield through functional specialization of each layer.
Solution Approach 2:
The invention uses composite material structure combining different dielectric materials (e.g., silicon oxide, silicon nitride, silicon oxynitride) with complementary properties. Each material is selected for its specific characteristics: low crack propensity, appropriate dielectric constant, moisture barrier properties, or hydrogen diffusion resistance. The composite structure achieves superior overall performance that none of the individual materials could provide alone, resolving the yield loss issue while keeping the process compatible with existing manufacturing capabilities.
2Ease of manufacture
If a single dielectric material is used in the ILD structure, then the structure is homogeneous and easy to manufacture, but hydrogen diffusion affects threshold voltage and device performance
Solution Approach 1:
The invention introduces intermediate layers (second dielectric layer and passivation layer) between the first dielectric layer and the external environment. These intermediate layers act as mediators that block hydrogen diffusion pathways while maintaining the overall structural integrity and electrical functionality. The second dielectric layer with different material composition creates a diffusion barrier, and the passivation layer provides an additional protective interface, effectively preventing hydrogen from reaching the transistor channels without complicating the manufacturing process.
Solution Approach 2:
Different regions of the ILD structure are assigned different material compositions and properties tailored to local requirements. The first dielectric layer near the transistor uses materials optimized for electrical insulation, while the second dielectric layer uses materials with low hydrogen content and diffusion resistance, and the passivation layer uses materials with excellent moisture and hydrogen barrier properties. This local quality differentiation addresses hydrogen diffusion issues in critical regions while maintaining manufacturing efficiency.
3Productivity
If the ILD structure lacks passivation layers, then the manufacturing process is simpler and faster, but moisture and hydrogen diffusion degrade device performance
Solution Approach 1:
The passivation layer is incorporated into the ILD structure during the fabrication process itself, performing the protective function preliminarily before devices are subjected to environmental exposure or subsequent processing steps. This preliminary protection prevents moisture and hydrogen diffusion from the outset, eliminating the need for separate post-fabrication passivation treatments and maintaining fabrication productivity while ensuring device performance integrity.
Solution Approach 2:
The passivation layer serves multiple functions simultaneously: it acts as a moisture barrier, hydrogen diffusion barrier, mechanical protection layer, and electrical insulation layer. By combining these functions into a single integrated layer within the ILD structure, the invention achieves comprehensive device protection without adding significant process complexity or reducing fabrication speed, as the same deposition equipment and materials are used.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The multi-layer ILD structure enhances device performance by reducing yield loss, improving contact annealing, and providing precise tuning of oxide transistor properties, while also offering passivation against moisture and hydrogen diffusion.
Implementation Method 1
forming a first sublayer including a first dielectric material on a gate structure and forming a second sublayer including the first dielectric material on the first sublayer. Forming the first sublayer includes depositing the first dielectric material of the first sublayer at a first deposition rate
Implementation Method 2
forming the second sublayer includes depositing the first dielectric material of the second sublayer at a second deposition rate less than the first deposition rate
Implementation Method 3
forming a second dielectric layer of the ILD structure by forming a third sublayer including a second dielectric material different from the first dielectric material. forming the third sublayer includes depositing the second dielectric material of the third sublayer at a third deposition rate
Data Source
AI summary
A transistor device includes a channel region, a first source/drain region adjacent to a first end of the channel region and a second source/drain region adjacent to a second end of the channel region, a gate structure disposed on the channel region, the first source/drain region and the second source/drain region, and an interlayer dielectric (ILD) structure disposed on the gate structure. The ILD structure includes a first dielectric layer including a first set of sublayers. The first set of sublayers includes a first sublayer including a first dielectric material having a first hydrogen concentration and a second sublayer including the first dielectric material having a second hydrogen concentration lower than the first hydrogen concentration. The ILD structure further includes a second dielectric layer including a second set of sublayers. The second set of sublayers includes a third sublayer including a second dielectric material different from the first dielectric material.