Void-Free Trench Fill Using Angled Seed Layer Etching
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Solution Overview
Problem
Traditional chemical vapor deposition (CVD) methods for filling trenches in semiconductor devices often result in voids and seams due to overhang pinch-off and 'bread-load' effects, making the process time-consuming and complex, and requiring additional surface treatments or pre-existing metal at the trench bottom.
Innovation Solution
The method involves directional etching to remove a seed layer from the sidewalls of trenches at a non-zero angle, allowing for void-free material deposition by maintaining the seed layer on the trench surface, followed by filling with metal using chemical vapor deposition or atomic layer deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional CVD methods are used to fill trenches, then material deposition is achieved, but voids and seams form due to overhang pinch-off and bread-load effects
Solution Approach 1:
The patent applies preliminary action by performing angled ion etching to remove the seed layer from sidewalls before the main CVD deposition process. This pre-treatment modifies the trench geometry to prevent overhang pinch-off during filling, ensuring void-free deposition without requiring complex in-situ adjustments during the actual filling process.
Solution Approach 2:
The patent changes the deposition parameters by using angled ion etching at specific angles (e.g., 15-45 degrees) to selectively remove seed layer from sidewalls while preserving the bottom seed layer. This parameter modification creates optimal conditions for subsequent CVD filling, preventing bread-load effects and ensuring uniform material deposition throughout the trench.
2Ease of manufacture
If traditional CVD trench filling is performed, then material is deposited, but additional surface treatments and pre-existing metal are required
Solution Approach 1:
The patent extracts the problematic seed layer from the sidewalls using angled ion etching, removing the source of overhang formation and bread-load effects. This extraction simplifies the subsequent deposition process by eliminating the need for complex surface treatments and pre-existing metal structures, reducing overall process flow complexity while maintaining ease of manufacture.
3Reliability
If angled ion etching is used to remove seed layer from sidewalls, then void-free deposition is achieved, but additional processing steps are added
Solution Approach 1:
The patent merges the seed layer removal function into the angled ion etching step, which simultaneously prepares the sidewalls for void-free deposition. By combining multiple functions (seed layer removal, surface preparation, and geometry optimization) into a single integrated process step, the patent achieves reliable void-free trench fills without proportionally increasing the number of discrete processing steps, thereby maintaining manufacturing efficiency.
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 enables void-free trench fills with improved conductivity, reduced processing complexity, and increased manufacturing efficiency by eliminating the need for additional lithography and etching procedures, while maintaining uniformity and reducing damage from chemical-mechanical polishing.
Implementation Method 1
removing the seed layer from the first sidewall and the second sidewall using an angled ion etch oriented at a non-zero angle of inclination relative to a perpendicular extending from the trench surface
Implementation Method 2
forming a fill material over the device layer by chemical vapor deposition
Implementation Method 3
forming a fill material over the device layer by atomic layer deposition
Data Source
AI summary
Embodiments herein include void-free material depositions on a substrate (e.g., in a void-free trench-filled (VFTF) component) obtained using directional etching to remove predetermined portions of a seed layer covering the substrate. In several embodiments, directional etching followed by selective deposition can enable fill material (e.g., metal) patterning in tight spaces without any voids or seams. Void-free material depositions may be used in a variety of semiconductor devices, such as transistors, dual work function stacks, dynamic random-access memory (DRAM), non-volatile memory, and the like.