Multiple Metallization Scheme for FinFET Trench Uniformity
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Solution Overview
Problem
The formation of Fin Field-Effect Transistors (FinFETs) and other integrated circuit components faces challenges in controlling contact plugs to gates and source/drain regions due to the difficulty in achieving uniformity in multiple metal layer deposition within trenches, which is resource-intensive and requires complex mask patterning processes.
Innovation Solution
A multiple metallization scheme that uses ion implantation to make a portion of the metal fill soluble or reactive to a wet cleaning agent, allowing for controlled removal without dry etching or multiple etch masks, enabling the formation of uniform metal layers by repeating the process to achieve up to ten distinct metal layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple metal layers are deposited within a single trench to achieve superior conductive properties, then electrical conductivity is improved, but manufacturing complexity and cost increase due to expensive deposition processes and difficulty in achieving uniform thickness
Solution Approach 1:
The patent divides the metal fill into multiple distinct layers by selectively removing portions at different depth ranges. The first metal layer is formed by removing metal within a first depth range from the surface, and the second metal layer is formed by removing metal within a second depth range, creating segmented metal structures with uniform thickness control without requiring multiple deposition cycles
Solution Approach 2:
The patent performs preliminary metal deposition to fill the entire trench depth with metal material before selective removal. This preliminary action allows subsequent selective etching to create multiple uniform layers from a single deposition, avoiding the need for multiple deposition processes and their associated complexity
2Reliability
If conventional deposition processes are used to form multiple metal layers, then conductive properties can be achieved, but uniformity in thickness control deteriorates making the process difficult to manage
Solution Approach 1:
The patent replaces mechanical deposition control (which struggles with uniformity) with a chemical etching-based approach. By using selective chemical removal processes with controlled depth ranges, the invention achieves superior thickness uniformity for each metal layer, as the etching process naturally produces more consistent results than sequential deposition
Solution Approach 2:
The patent changes the control parameter from deposition thickness control to etching depth control. By specifying removal depth ranges rather than deposition thickness, the process achieves better uniformity, as etching depth can be more precisely controlled and measured than deposition thickness in complex trench structures
3Manufacturing precision
If multiple etch masks are used to form multiple metal layers, then layer definition is achieved, but resource intensity and process complexity increase
Solution Approach 1:
The patent extracts and removes only the unnecessary portions of the metal fill at specific depth ranges, leaving the desired metal layers in place. This selective removal approach eliminates the need for multiple etch masks, as the metal layers are defined by what remains after selective etching rather than by multiple masking and patterning operations
Solution Approach 2:
The patent uses a single metal deposition process that fills the entire trench, which then serves as a universal precursor for forming multiple different metal layers through selective removal. This multi-functional approach allows one deposition to create multiple layers, eliminating the need for separate deposition and masking processes for each layer
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 method ensures uniform thickness and predictable electrical properties of metal layers, reducing resource intensity and complexity in the manufacturing process while maintaining good electrical conductivity and compatibility with other materials.
Implementation Method 1
implanting first ions into a first portion of the first metal
Data Source
AI summary
A multiple metallization scheme in conductive features of a device uses ion implantation in a first metal layer to make a portion of the first metal layer soluble to a wet cleaning agent. The soluble portion may then be removed by a wet cleaning process and a subsequent second metal layer deposited over the first metal layer. An additional layer may be formed by a second ion implantation in the second metal layer may be used to make a controllable portion of the second metal layer soluble to a wet cleaning agent. The soluble portion of the second metal layer may be removed by a wet cleaning process. The process of depositing metal layers, implanting ions, and removing soluble portions, may be repeated until a desired number of metal layers are provided.