Backside Wafer Deposition Chamber for Flatness Without Front-Side Damage
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Semiconductor fabrication processes, such as photolithography and annealing, cause substrate distortion and bowing due to stress from multiple film layers, leading to overlay errors and reduced feature uniformity, which conventional chucking techniques struggle to correct effectively, especially when extreme ultraviolet systems require non-vacuum clamping and existing deposition methods damage the backside surface.
Innovation Solution
A backside deposition system that applies films to the substrate's backside to counteract stress, using a substrate support mechanism that seals the processing chamber to prevent deposition on the front side, maintaining the substrate's original orientation and using a separate temperature control environment to manage substrate temperature without direct contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If conventional chucking techniques are used to flatten substrate, then substrate flatness is improved, but the backside surface is damaged
Solution Approach 1:
Instead of depositing film on the front side of the substrate (conventional approach), the invention deposits film on the backside surface. This inversion allows the substrate to be held by its perimeter edge rather than its backside surface, preventing damage while still achieving flatness correction through stress compensation on the damaged side.
Solution Approach 2:
A perimeter clamp mechanism serves as an intermediary that holds the substrate by its edge rather than its backside surface. This mediator allows the substrate to be secured for deposition without direct contact between the clamp and the backside surface, thus preventing damage while maintaining control during the process.
2Ease of manufacture
If deposition is performed on the front side of substrate, then film application is simplified, but substrate distortion increases due to additional stress
Solution Approach 1:
The invention inverts the conventional deposition approach by depositing film on the backside surface rather than the front side. This allows the deposited film to generate compensating stress that counteracts existing substrate bowing and distortion, improving flatness while maintaining process simplicity.
3Manufacturing precision
If vacuum clamping is used to prevent substrate expansion, then overlay precision is improved, but EUV systems cannot be used due to vacuum environment requirements
Solution Approach 1:
The invention replaces vacuum clamping (mechanical system requiring vacuum environment) with electrostatic clamping that can operate in atmospheric pressure. The electrostatic chuck uses electrical fields to hold the substrate, eliminating the need for vacuum and enabling compatibility with EUV systems while still preventing substrate expansion and maintaining overlay precision.
4Stability of the object's composition
If clamping force is increased to prevent substrate slip, then substrate position stability is improved, but substrate expansion is exacerbated due to stress
Solution Approach 1:
The invention replaces mechanical clamping force with electrostatic clamping that distributes stress more uniformly across the substrate. This eliminates the localized high-stress points caused by mechanical clamps, preventing both substrate slip and stress-induced expansion, thereby maintaining both position stability and shape integrity.
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 flattens the substrate by applying compensating stresses on the backside, reducing distortion and overlay errors, while protecting the front side from damage during film deposition, thereby improving yield and reducing defects.
Implementation Method 1
maintaining a pressure differential between an upper section and a lower section of a processing chamber sufficient to prevent passage of deposition gas from the lower section to the front side surface of the substrate
Implementation Method 2
depositing a film on a backside surface of a substrate without depositing on a front side surface of the substrate
Implementation Method 3
depositing a film on a backside surface of a substrate
Implementation Method 4
a heating mechanism positioned in the upper section and configured to heat the substrate without contacting the front side surface of the substrate
Implementation Method 5
a heating mechanism positioned in the upper section and configured to heat the substrate without contacting the front side surface of the substrate
Data Source
AI summary
Techniques herein include a process chamber for depositing thin films to backside surfaces of wafers to reduce wafer bowing and distortion. A substrate support provides an annular perimeter seal around the bottom and/or side of the wafer which allows the majority of the substrate backside to be exposed to a process environment. A supported wafer separates the chamber into lower and upper chambers that provide different process environments. The lower section of the processing chamber includes deposition hardware configured to apply and remove thin films. The upper section can remain a chemically inert environment, protecting the existing features on the top surface of the wafer. Multiple exhausts and differential pressures are used to prevent deposition gasses from accessing the working surface of a wafer.