Pulsed DC Power Supply for Plasma Chamber Film Uniformity
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Solution Overview
Problem
Current plasma-based sputtering deposition methods using high-frequency voltage sources are expensive, complex, and fail to achieve uniformity and stoichiometric control, particularly when dealing with insulating deposition materials that coat the anode, preventing electron collection and leading to inefficient processing.
Innovation Solution
A method employing pulsed DC power with a negative potential followed by a positive potential, and a recovery potential, applied to a cathode in a plasma processing chamber, along with a power control component that adjusts power pulses based on impedance monitoring to sustain a plasma process and deposit films uniformly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-frequency voltage sources are used to generate plasma, then plasma generation is achieved, but the system becomes expensive and complex to construct and maintain
Solution Approach 1:
The patent changes the electrical parameter from high-frequency AC voltage to pulsed DC voltage. The power supply applies negative DC pulses to the cathode during sputtering portions and positive DC pulses during reverse-potential portions, eliminating the need for expensive high-frequency voltage sources while maintaining plasma generation capability
Solution Approach 2:
The patent employs a simple, inexpensive pulsed DC power supply instead of complex high-frequency equipment. The straightforward circuit design with basic voltage switching capabilities significantly reduces construction and maintenance costs while achieving the required plasma processing functions
2Quantity of substance
If insulating deposition material coats the anode, then deposition occurs, but electron collection is prevented and processing efficiency decreases
Solution Approach 1:
The patent implements periodic reversal of electrode potentials. During anode phases, the electrode collects electrons for plasma generation; during cathode phases, it sputters target material. This periodic switching prevents insulating material accumulation that would otherwise block electron collection, maintaining continuous processing efficiency
Solution Approach 2:
The patent makes the electrode roles dynamic rather than static. Each electrode alternates between functioning as an anode and as a cathode based on applied voltage polarity, allowing both material deposition and electron collection functions to be performed by both electrodes over time, preventing the performance degradation caused by fixed anode coating
3Object-generated harmful factors
If alternating pulsed direct current power sources are used, then electrode polarity reversal cleans insulating material, but uniformity and particle generation thresholds are not achieved
Solution Approach 1:
The patent employs periodic voltage pulse sequences with distinct phases: negative potential pulses for sputtering, positive potential pulses for cleaning, and recovery periods. This structured periodic action maintains electrode surfaces free of insulating deposits while achieving uniform film deposition and controlling particle generation through optimized pulse parameters
Solution Approach 2:
The patent implements monitoring and control mechanisms that adjust pulse parameters based on process conditions. By monitoring plasma characteristics and deposition rates, the system optimizes pulse duration, amplitude, and frequency to achieve uniform film uniformity and control particle generation thresholds while maintaining the benefits of polarity reversal
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 more efficient and uniform film deposition, reduces contamination, and allows for precise control over target material utilization, improving the quality and consistency of thin films while minimizing electrode wear and maintenance needs.
Implementation Method 1
a power supply creates an electric potential between a cathode and one or more anodes that are placed in a plasma chamber containing the process gases that form the plasma
Implementation Method 2
When using these processes for deposition, the plasma acts upon the material of a target
Implementation Method 3
Plasma ions are accelerated towards the target and cause target material to be dislodged from the cathode surface on impact
Implementation Method 4
the plasma acts upon the material of a target (also referred to as a sputtering source) placed in the plasma chamber that normally comprises the cathode surface. Plasma ions are accelerated towards the target and cause target material to be dislodged from the cathode surface on impact
Implementation Method 5
The process of reversing polarities allows the electrodes to alternately act as an anode and as a cathode, and the sputtering process that occurs during the cathode phase cleans off any deposited insulating material and permits uninhibited operation of the electrode as an anode during the anode phase
Implementation Method 6
The dislodged target material is then deposited on a substrate to form a film (e.g., thin film). The film may constitute material sputtered by the plasma from the target surface
Data Source
AI summary
Methods and apparatus for applying pulsed DC power to a plasma processing chamber are disclosed. In some implementations, frequency of the applied power is varied to achieve desired processing effects such as deposition rate, arc rate, and film characteristics. In addition, a method and apparatus are disclosed that utilize a relatively high potential during a reverse-potential portion of a particular cycle to mitigate possible nodule formation on the target. The relative durations of the reverse-potential portion, a sputtering portion, and a recovery portion of the cycle are adjustable to effectuate desired processing effects.