Wafer Backside Actuator Films for Programmable Bow Correction
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Solution Overview
Problem
Semiconductor fabrication processes face challenges in maintaining wafer shape uniformity and planarity due to significant deformation and bowing, particularly in 3D NAND devices, which can lead to non-uniformities, overlay mismatch, and wafer handling issues, and existing methods like silicon nitride film deposition are complex and time-consuming.
Innovation Solution
The application of chemical actuator films on the wafer's backside, responsive to external stimuli such as light or heat, allows for programmable and reversible stress adjustment to correct both global and local shape deformations, using techniques compatible with high-throughput track tools.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If silicon nitride film deposition is used to correct wafer shape, then wafer shape uniformity is improved, but process complexity and time consumption increase
Solution Approach 1:
The patent replaces the mechanical/thermal process of silicon nitride film deposition with a photochemical actuation system. Light-sensitive actuator films are deposited on the wafer backside and activated by specific wavelength light to generate controlled stress that corrects wafer shape, eliminating the need for complex deposition and etching processes.
Solution Approach 2:
The patent changes the fundamental parameter of stress application from passive film deposition to active light-triggered actuation. By using photosensitive or thermally responsive actuator materials that can be activated on-demand with light or heat, the system achieves dynamic control over wafer shape correction without complex processing steps.
2Manufacturing precision
If silicon nitride film deposition is used to correct wafer shape, then wafer shape uniformity is improved, but processing time increases
Solution Approach 1:
The actuator films are deposited on the wafer backside in advance during normal fabrication processes. When shape correction is needed, pre-programmed light patterns or heat application immediately activate the actuators to correct the wafer shape, eliminating the need for time-consuming deposition and etching steps that would otherwise be required.
Solution Approach 2:
The patent replaces the time-intensive silicon nitride deposition and patterned etching process with rapid photochemical or thermal actuation. The light-sensitive or thermally responsive actuator materials can be activated in seconds or minutes, dramatically reducing the time required for wafer shape correction while maintaining high precision.
3Manufacturing precision
If multi-directional actuator films are applied, then wafer shape correction precision is improved, but film complexity increases
Solution Approach 1:
The patent divides the wafer backside into multiple regions, each coated with actuator materials having different stress characteristics. By segmenting the actuator film into zones with different photochemical or thermal responses, the system can independently control stress in different directions and locations, achieving precise multi-directional shape correction.
Solution Approach 2:
The patent applies different actuator material compositions or orientations to different locations on the wafer backside. Each local region has tailored properties that generate specific stress patterns when activated, allowing precise control over the direction and magnitude of shape correction at each location without requiring a uniformly complex film structure.
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
Enables efficient and adaptable wafer shape optimization, improving overlay accuracy and reducing bowing, thereby enhancing the precision of photolithographic patterning and overall device performance.
Implementation Method 1
the actuator film being sensitive to a predetermined activating stimulus, the actuator film configured to undergo a positional change in response to activation of the actuator material
Implementation Method 2
activating the actuator material in the actuator film via the predetermined activating stimulus at locations along the first surface of the wafer and causing a stress within the actuator film
Data Source
AI summary
Techniques herein include methods for coating a single layer actuator film or multi-layer actuator film on the backside of a wafer. The actuator film includes one or more chemical actuators. Chemical actuators are various molecules, crystals, chemical compounds and other chemical compositions that are capable of imposing directional stress in response to application of an external stimulus on the chemical actuator. The external stimulus can include a particular wavelength of light or polarization of light, or heat (or directed infrared radiation) or load, which can include load-responsive actuation or pressure-responsive actuation.