RF Filter with Twisted Magnetic Wire Coil for Bias Isolation
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Solution Overview
Problem
In semiconductor fabrication processes, RF power used to generate plasma and bias voltage can interfere with and damage power supplies, and connecting a heater power supply to RF electrodes loads the RF power, reducing its efficiency, necessitating an RF filter to isolate the RF electrode from the heater power supply.
Innovation Solution
An RF filter with an inductive element comprising twisted magnetic wires forming an undivided coil with varying turn pitches and terminating capacitive elements connected to ground, preventing RF power intrusion into DC or AC power supplies while allowing electrical current transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If RF power is transmitted to generate plasma and bias voltage, then plasma generation and bias voltage are achieved, but RF power interferes with and damages power supplies
Solution Approach 1:
The filter divides the power transmission path into separate frequency bands using multiple coil sections with different turn pitches, allowing RF power to reach the plasma generation system while blocking it from the power supply
Solution Approach 2:
The filter acts as an intermediary component between the RF power source and the power supply, using inductive and capacitive elements to selectively transmit or block RF power based on frequency characteristics
2Adaptability or versatility
If heater power supply is connected to RF electrode, then heating function is provided, but RF power loads the heater power supply reducing efficiency
Solution Approach 1:
The filter segments the electrical connection between heater power supply and RF electrode, creating frequency-selective paths that allow DC/AC heating current while blocking RF power from loading the heater supply
Solution Approach 2:
Different sections of the filter have different inductive properties (varying turn pitches) tailored to handle specific frequency ranges, with each section optimized for its local function in the frequency spectrum
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 RF filter effectively isolates RF power from power supplies, maintaining electrical current transmission and improving RF power efficiency by ensuring uniform impedance across channels, thus enhancing process uniformity and reducing power loss.
Implementation Method 1
An inductive element is disclosed that includes at least two coil sections collectively forming an undivided coil of a cable of twisted magnetic wires
Implementation Method 2
A set of terminating capacitive elements is disclosed that includes a separate terminating capacitive element for each wire of the cable of twisted magnetic wires
Data Source
AI summary
A radiofrequency (RF) filter includes an inductive element having multiple coil sections collectively forming an undivided coil of a cable of twisted magnetic wires. At least two adjacent coil sections have different turn pitches. The cable of twisted magnetic wires includes two wires per channel and is configured for at least one channel. The cable of twisted magnetic wires at a first end of the inductive element is configured for connection to an electrical component that is to receive power from a power supply. The cable of twisted magnetic wires at a second end of the inductive element is configured for connection to the power supply. Terminating capacitive elements are electrically connected between a reference ground potential and a respective wire of the cable of twisted magnetic wires at respective locations between the second end of the inductive element and the power supply.