Backside Contact Placeholder Templating for Precise Depth Control
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Solution Overview
Problem
Current techniques for forming backside contact placeholders in transistor fabrication face challenges with controlling the dimensions and variability of metal recess processing, which is critical for deploying advanced transistor structures and backside contacts.
Innovation Solution
The use of a dielectric material such as a carbon hardmask is recessed to form a well-controlled structure, which is then replaced with a metal placeholder using templated bottom-up growth or spatially confined deposition methods, ensuring precise placement and reliability of backside contacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If metal recess processing is used to form backside contact placeholders, then the placeholders can be created for backside contact access, but the depth control and dimensional precision are poor with high variation
Solution Approach 1:
The patent introduces an intermediary material (dielectric material or sacrificial material) that is deposited to a precise thickness to form the backside contact placeholder. This intermediary material serves as a template that defines the placeholder dimensions, replacing the direct metal recess approach. The intermediary material can be selectively removed later to create the final contact structure, thereby achieving precise depth control through deposition thickness rather than difficult recess etching.
Solution Approach 2:
The patent changes the formation approach from subtractive (recessing metal) to additive (depositing dielectric or sacrificial material). By controlling the deposition thickness parameter of the intermediary material, precise depth and dimensional control are achieved. This parameter change from etch depth control to deposition thickness control resolves the precision and reliability issues inherent in metal recess processing.
2Reliability
If advanced transistor structures like GAA or nanoribbon are deployed, then transistor performance is improved, but the fabrication complexity and difficulty increase
Solution Approach 1:
The patent performs preliminary action by forming the backside contact placeholders using precisely controlled dielectric deposition or sacrificial material formation before the complex transistor fabrication steps. This early establishment of contact placeholder structures with accurate dimensions simplifies subsequent processing and reduces the overall fabrication complexity, even as transistor structures become more advanced.
Solution Approach 2:
The intermediary material serves as a guiding template that simplifies the fabrication of complex transistor structures. By establishing precise contact placeholder locations and dimensions early in the process, the intermediary structure acts as a reference framework that guides subsequent transistor formation steps, thereby reducing overall process complexity despite the advancement to GAA or nanoribbon devices.
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 provides improved process control and reliability in forming backside contacts, enabling higher performance and density in integrated circuits by reducing resistance and facilitating the integration of gate-all-around and nanoribbon transistors.
Implementation Method 1
a dielectric material such as a carbon hardmask is recessed to form a well-controlled structure
Implementation Method 2
replaced with a metal placeholder using templated bottom-up growth or spatially confined deposition methods
Implementation Method 3
replaced with a metal placeholder using templated bottom-up growth or spatially confined deposition methods
Data Source
AI summary
Devices, transistor structures, systems, and techniques are described herein related to backside contacts for field effect transistors formed using a backside placeholder contact. The backside placeholder contact is templated from a recessed dielectric material such as a recessed carbon hardmask. The recessed dielectric material is formed and replaced with a placeholder metal in frontside processing, and the placeholder metal is revealed and replaced from the transistor backside to form the backside contact.