Faraday Shield Plasma Density Decoupling Structure
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Solution Overview
Problem
In semiconductor manufacturing, the adherence of non-volatile reaction products to the dielectric window in plasma etching chambers interferes with the etching process, leading to reduced magnetic flux transmission and decreased control over plasma directionality, especially when processing high aspect ratio features, necessitating frequent chamber cleaning and affecting wafer throughput.
Innovation Solution
A Faraday shield with a three-zone slot configuration and a band ring is placed between the electrostatic chuck and the dielectric window, decoupling the magnetic flux control between the inner and outer zones of the TCP coil, allowing independent control of magnetic field distribution and plasma density uniformity across the wafer surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a Faraday shield is placed in the plasma etching chamber to protect the dielectric window from non-volatile reaction products, then the dielectric window is protected from deposition and cleaning frequency is reduced, but the magnetic flux transmission to the plasma is diminished, reducing control over plasma directionality
Solution Approach 1:
The Faraday shield is divided into multiple zones (inner zone, middle zone, outer zone) with different slot configurations. Each zone has radially extending slots oriented at different angles, allowing selective control of magnetic flux transmission to different regions of the plasma while maintaining protection against deposition.
Solution Approach 2:
Different zones of the Faraday shield have locally optimized slot patterns tailored to their specific functional requirements. The inner zone slots are oriented to control central plasma density, while outer zone slots are oriented to control edge plasma characteristics, enabling localized magnetic field management.
2Ease of manufacture
If the Faraday shield uses a simple slot configuration to protect the dielectric window, then manufacturing is simplified, but plasma density uniformity across the wafer surface cannot be controlled
Solution Approach 1:
The shield is segmented into zones with distinct slot patterns that can be manufactured using standardized processes. Each zone's slot configuration is optimized for its specific function, allowing modular manufacturing while achieving complex plasma control objectives.
Solution Approach 2:
The slot orientations are arranged in specific angular patterns across different radial zones, creating a two-dimensional control matrix that enables precise plasma density management. This dimensional approach to slot arrangement provides fine-tuned control without requiring complex three-dimensional structures.
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 configuration enhances plasma density control and protects the dielectric window from plasma byproduct buildup, improving etch uniformity and reducing deposition on the shield, thereby maintaining magnetic flux transmission and increasing wafer throughput, especially for larger wafers.
Implementation Method 1
a Faraday shield having a three zone slot configuration correlated to a TCP coil disposed over the dielectric window of the chamber
Implementation Method 2
The Faraday shield includes radial slots in each of the zones... the ring band provides the ability to separately control the magnetic flux provided to the substrate
Implementation Method 3
a TCP coil disposed over the dielectric window... the chamber coil performs a function analogous to that of a primary coil in a transformer
Data Source
AI summary
A Faraday shield and a plasma processing chamber incorporating the Faraday shield is are provided. The plasma chamber includes an electrostatic chuck for receiving a substrate, a dielectric window connected to a top portion of the chamber, the dielectric window disposed over the electrostatic chuck, and a Faraday shield. The Faraday shield is disposed inside of the chamber and defined between the electrostatic chuck and the dielectric window. The Faraday shield includes an inner zone having an inner radius range that includes a first and second plurality of slots and an outer zone having an outer radius range that includes a third plurality of slots. The inner zone is adjacent to the outer zone. The Faraday shield also includes a band ring separating the inner zone and the outer zone, such that the first and second plurality of slots do not connect with the third plurality of slots.