Semiconductor Air Gap Formation With Controlled Void Geometry
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Solution Overview
Problem
Existing methods for forming air gaps in semiconductor devices face challenges in controlling the volume, height, and reproducibility of air gaps, which are crucial for reducing the dielectric constant and improving signal propagation.
Innovation Solution
A method involving directional sputtering and deposition processes to shape patterned features on a substrate, creating protrusions and voids between adjacent features, allowing for controlled formation of low dielectric constant regions through the use of sputtering species and directional plasma enhanced chemical vapor deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a chemical vapor deposition (CVD) process is used to form air gaps, then void formation is achieved, but control over air gap volume, height, and reproducibility is poor
Solution Approach 1:
The patent applies preliminary action by first forming a mandrel structure with a specific geometry (including a recess portion) before the air gap formation process. This pre-configured mandrel serves as a template that dictates the precise shape, volume, and position of the subsequent air gap, eliminating the need for complex real-time control during void formation and ensuring high reproducibility across manufacturing batches.
Solution Approach 2:
The patent introduces a mandrel structure as an intermediary element that mediates between the fabrication process and the final air gap structure. The mandrel acts as a physical template that transfers its geometric information to the air gap during the deposition process, simplifying control by decoupling the complex air gap formation from direct process parameter control and instead using the mandrel's pre-defined geometry as the controlling factor.
2Reliability
If voids are formed between adjacent conductors, then dielectric constant is reduced, but reproducibility and variation control are challenging
Solution Approach 1:
The mandrel structure is prepared in advance with a precisely engineered recess portion that defines the future air gap's geometry. This preliminary configuration ensures that when the air gap forms, it automatically inherits the mandrel's precise dimensions and positioning, guaranteeing high reproducibility of air gap volume and height across different devices and manufacturing batches, thereby ensuring consistent signal propagation characteristics.
Solution Approach 2:
The patent controls air gap parameters by changing the physical state and geometry of the mandrel structure during fabrication. By precisely controlling the mandrel's recess portion dimensions and shape, the air gap's volume, height, and position are determined through geometric parameters rather than process conditions, significantly improving reproducibility and reducing variation in the final air gap structure.
3Productivity
If air gaps are formed to improve signal propagation, then dielectric constant decreases, but control over void location and size is difficult
Solution Approach 1:
The mandrel structure is fabricated beforehand with a specifically designed recess portion located at the desired position between adjacent conductors. This pre-positioned recess serves as a spatial template that ensures the air gap forms exactly where needed with precise location control, eliminating the difficulty of controlling void position during the air gap formation process itself.
Solution Approach 2:
The mandrel acts as an intermediary spatial reference that bridges the design intent and the final air gap location. By using the mandrel's pre-configured recess as a physical template, the system transfers precise location information from the fabrication stage to the final device structure, ensuring accurate air gap positioning without requiring complex real-time control mechanisms.
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 effectively controls the location, size, and variability of air gaps, ensuring that voids are buried below the surface, enhancing the reproducibility and effectiveness of low dielectric constant regions, thus improving signal propagation in semiconductor devices.
Implementation Method 1
directing a sputtering species in a first exposure to the array of patterned features, wherein an upper portion of a patterned feature of the array of patterned features forms a protrusion
Implementation Method 2
directing a depositing species in a second exposure to the array of patterned features, wherein an array of voids is formed between adjacent patterned features
Implementation Method 3
directing a depositing species in a second exposure to the array of patterned features
Implementation Method 4
the second exposure comprising a directional plasma enhanced chemical vapor deposition process, wherein an array of voids is formed between adjacent patterned features
Data Source
AI summary
A method may include providing an array of patterned features on a substrate, the array of patterned features characterized by a spacing. The method may include directing a sputtering species in a first exposure to the array of patterned features, wherein an upper portion of a patterned feature of the array of patterned features forms a protrusion, extending towards an adjacent patterned feature, of the array of patterned features. The method may also include directing a depositing species in a second exposure to the array of patterned features, wherein an array of voids is formed between adjacent patterned features.