Plasma Ignition via Collimator Bias Voltage
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Solution Overview
Problem
Conventional substrate processing chambers face challenges in reliably igniting a plasma at low power and low pressure levels, often requiring multiple attempts and leading to defects and throughput issues in semiconductor manufacturing.
Innovation Solution
A method involving flowing a process gas to increase chamber pressure, applying a bias voltage to a collimator, and then powering a sputtering source to ignite the plasma, while maintaining a lower pressure after ignition, effectively reducing the number of ignition retries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If plasma ignition is attempted at low power and low pressure levels, then energy consumption is reduced, but ignition reliability deteriorates requiring multiple retries
Solution Approach 1:
The collimator is biased with a voltage (e.g., -100V to -300V) before plasma ignition begins. This preliminary biasing creates an electric field that pre-accelerates ions toward the substrate, facilitating easier plasma breakdown at lower power levels and reducing ignition retries while maintaining low energy consumption
2Reliability
If multiple ignition retries are performed, then plasma ignition success is achieved, but manufacturing defects and particle contamination increase
Solution Approach 1:
By biasing the collimator before ignition, the system achieves reliable plasma breakdown in fewer attempts (ideally one attempt), thereby preventing the generation of defects and particle contamination that would result from multiple high-voltage ignition retries
3Reliability
If conventional high voltage is used for plasma breakdown, then plasma ignition is achieved, but processing time increases due to multiple retries
Solution Approach 1:
The collimator bias is applied in advance before the plasma ignition sequence begins. This preliminary action creates favorable conditions for breakdown, enabling the plasma to ignite in fewer attempts and significantly reducing the time loss associated with multiple ignition retries
Solution Approach 2:
The system changes the electrical parameter of the collimator by applying a bias voltage, which modifies the electric field distribution in the chamber. This parameter change facilitates easier plasma breakdown at lower power levels, reducing both the number of retries and the total processing time
4Power
If collimator bias is applied before plasma ignition, then plasma breakdown is facilitated at low power, but additional voltage control complexity is introduced
Solution Approach 1:
The collimator, which already serves as a structural component for directing particle trajectories, is given an additional function by biasing it with voltage. This multi-functionality allows the same component to both physically collimate particles and electrically facilitate plasma breakdown, avoiding the need for separate ignition electrodes or additional hardware
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 enables reliable low-power and low-pressure plasma ignition, reducing defects and improving process efficiency by limiting ignition retries to fewer than three attempts.
Implementation Method 1
flowing a process gas into a process chamber to increase a pressure within the process chamber to a first pressure
Implementation Method 2
applying a first bias voltage from a collimator power source to a collimator disposed within the process chamber
Implementation Method 3
Sputtering, also known as physical vapor deposition (PVD), is a method of forming metallic features in integrated circuits. Sputtering deposits a material layer on a substrate. A source material, such as a target, is bombarded by ions strongly accelerated by an electric field. The bombardment ejects material from the target, and the material then deposits on the substrate.
Implementation Method 4
applying a second power to a sputtering source disposed in the process chamber above the collimator after the first pressure has been reached and the first bias voltage is applied to ignite the plasma
Data Source
AI summary
Embodiments of method for igniting a plasma are provided herein. In some embodiments, a method for igniting a plasma includes: flowing a process gas into a process chamber to increase a pressure within the process chamber to a first pressure; applying a first bias voltage from a collimator power source to a collimator disposed within the process chamber; and applying a second power to a sputtering source disposed in the process chamber above the collimator after the first pressure has been reached and the first bias voltage is applied to ignite the plasma.