Coaxial Lift Assembly for Dynamic Pedestal Leveling in PECVD
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Solution Overview
Problem
Conventional lift devices in semiconductor process chambers suffer from parasitic plasma generation and non-uniform film deposition due to mechanical tolerance issues and lack of independent motion between components, leading to reduced deposition rates and film uniformity.
Innovation Solution
A multicomponent lift assembly system that includes a bottom bowl lift and a pedestal lift, allowing independent linear and angular motion, which reduces parasitic plasma generation by optimizing the RF energy path and aligning the pedestal with the showerhead, thereby enhancing film uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional linear motion is used to transfer the wafer pedestal, then the device structure is simple, but mechanical tolerance issues cause the pedestal surface and faceplate to be non-parallel, resulting in process non-uniformity
Solution Approach 1:
The lift mechanism is divided into two independent subsystems: a bottom bowl lift for vertical translation and a pedestal lift with multiple actuators for angular and positional adjustment. This segmentation allows each subsystem to be optimized independently, with the pedestal lift specifically addressing alignment uniformity through its multi-actuator design that can compensate for mechanical tolerances.
Solution Approach 2:
The system transitions from static fixed positioning to dynamic adjustable positioning. The pedestal lift includes multiple actuators that can dynamically adjust the pedestal's angular orientation and position relative to the showerhead, enabling real-time compensation for mechanical tolerance variations and achieving optimal alignment uniformity for each specific process requirement.
2Productivity
If RF power is applied to generate capacitive coupled plasma, then deposition rate is enhanced, but parasitic plasma is generated underneath the pedestal, reducing ion concentration and deposition rate
Solution Approach 1:
The harmful parasitic plasma generation is addressed by extracting or eliminating the problematic ground path configuration. The bottom bowl lift mechanism raises the bottom bowl to a process position that optimizes the RF energy path and prevents parasitic plasma formation underneath the pedestal, while maintaining the beneficial capacitive coupled plasma between the pedestal and showerhead faceplate for high deposition rates.
Solution Approach 2:
The bottom bowl acts as an intermediary component between the chamber floor and the pedestal assembly. By independently controlling the bottom bowl's position via the bottom bowl lift, the system can optimize the RF energy path and ground path configuration to prevent parasitic plasma while maintaining effective plasma generation in the process region.
3Object-generated harmful factors
If the bottom bowl is positioned too low, then parasitic plasma is generated, but if positioned too high, then the process volume is reduced and affects plasma generation
Solution Approach 1:
The bottom bowl position is made dynamically adjustable through the bottom bowl lift mechanism, which can raise or lower the bottom bowl to optimize both parasitic plasma prevention and process volume maintenance. This dynamic positioning allows the system to achieve the optimal balance between eliminating harmful parasitic plasma and maintaining sufficient process chamber volume for effective plasma generation and uniform film deposition.
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
The system increases deposition rates, reduces particle generation, and improves film uniformity by minimizing parasitic plasma formation and addressing mechanical tolerance issues through independent component alignment and orientation.
Implementation Method 1
the plurality of actuators are configured to cause relative linear and angular motion between the pedestal and the bottom bowl when one or more of the plurality of actuators causes at least a portion of the pedestal carrier to translate in the first direction
Implementation Method 2
An RF source coupled to the pedestal through a RF matching circuit and a faceplate of the gas distribution assembly grounded to the chamber body facilitate formation of a capacitive plasma coupling. The RF source provides RF energy to the pedestal to facilitate generation of the capacitive coupled plasma
Implementation Method 3
During a CVD process, the process gases in the chamber may be energized (e.g., excited) into a plasma by applying radio frequency (RF) power to the chamber from one or more RF sources coupled to the chamber, referred to as plasma-enhanced CVD (PECVD)
Data Source
AI summary
Embodiments described herein generally relate to process chambers with coaxial lift devices. In some embodiments, the device comprises both a bottom bowl lift and a pedestal lift. The bottom bowl lift supports a bottom bowl and is configured to move the bottom bowl into a position that reduces the process volume. The bottom bowl lift is co-axial with the pedestal lift and the bottom bowl lift and the pedestal lift are attached for vacuum operation. The pedestal lift includes multiple actuators to create a dynamic lift mechanism. Both systems complete a nested system such that the bottom bowl lift is adjustable and can close the bottom bowl creating a symmetric and small process volume. The pedestal lift can move independently to its process position and tilt in a desired direction without interference with the bottom bowl lift, increasing film uniformity on a processed substrate.