Stressed Dielectric Layer for Transistor Channel Mobility
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Solution Overview
Problem
Existing methods for forming semiconductor structures with stressed channel regions face challenges in effectively transmitting stress to the substrate, leading to insufficient stress in the channel regions, which can negatively impact charge carrier mobility and is not adaptable for transistors of different types, potentially harming performance or being detrimental.
Innovation Solution
A method involving the formation of a thicker dielectric layer with intrinsic stress over an etch stop layer, accompanied by a protective layer to prevent moisture intrusion and maintain stress, allowing for enhanced stress transmission and tailored stress application to individual transistor types.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If a thin dielectric layer with intrinsic stress is formed over the transistor element, then the manufacturing process is simple, but the stress transmission to the substrate is insufficient, leading to inadequate charge carrier mobility improvement
Solution Approach 1:
The patent divides the dielectric layer into multiple segments: a first dielectric layer in direct contact with the transistor element that provides stress transmission, and a second dielectric layer positioned above that provides protection. This segmentation allows the stress-transmitting function and protection function to be separated, enabling the thin first layer to effectively transmit stress while the thicker second layer provides adequate protection without interfering with stress transmission.
Solution Approach 2:
The patent introduces an intermediary structure (the two-layer dielectric configuration) where the first dielectric layer acts as a mediator between the transistor element and the second dielectric layer. This intermediary arrangement allows stress to be transmitted from the first dielectric layer to the substrate while the second dielectric layer provides protective functions, thus resolving the contradiction between maintaining simplicity and achieving sufficient stress transmission.
2Reliability
If the dielectric layer is made thicker to improve protection, then protection effectiveness increases, but stress transmission to the substrate is reduced
Solution Approach 1:
The patent segments the protective function and stress transmission function into different layers. The first dielectric layer, being thin, effectively transmits stress to the substrate. The second dielectric layer, being thicker, provides enhanced protection. This segmentation resolves the contradiction by assigning different thicknesses to different layers based on their specific functions.
Solution Approach 2:
The patent applies local quality by giving different properties to different parts of the dielectric structure. The first dielectric layer has properties optimized for stress transmission (thin thickness, specific material composition), while the second dielectric layer has properties optimized for protection (greater thickness, different material composition). This local differentiation allows each layer to excel at its specific function without compromising the other.
3Adaptability or versatility
If a single dielectric layer with intrinsic stress is used, then the manufacturing process is simple, but it cannot provide tailored stress for different transistor types
Solution Approach 1:
The patent applies local quality by enabling different stress characteristics in different regions. The first dielectric layer can be formed with stress characteristics optimized for the underlying transistor type, while the second dielectric layer provides additional protection. This allows tailored stress application to different transistor types (P-type or N-type) without significantly increasing manufacturing complexity, as the stress tailoring is achieved through material selection and layer configuration rather than complex processing.
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
This approach increases the stress influence on the semiconductor structure, improving charge carrier mobility in the channel region and ensuring that the stress benefits one transistor type without harming the other, thus enhancing the performance of both P-type and N-type transistors.
Implementation Method 1
A first dielectric layer with intrinsic stress is formed over an etch stop layer
Implementation Method 2
a protective layer adapted to reduce an intrusion of moisture into the first dielectric layer is formed over the first dielectric layer
Data Source
AI summary
A method of forming a semiconductor structure comprises providing a semiconductor substrate comprising at least one transistor element. An etch stop layer is formed over the transistor element. A stressed first dielectric layer is formed over the etch stop layer. A protective layer adapted to reduce an intrusion of moisture into the first dielectric layer is formed over the first dielectric layer. At least one electrical connection to the transistor element is formed. At least a portion of the protective layer remains over the first dielectric layer after completion of the formation of the at least one electrical connection.