Plasma Etching Upper Electrode Cleaning Using Negative Bias Voltage
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Solution Overview
Problem
In plasma etching processes, a significant challenge is the accumulation of deposits on the upper electrode, which reduces the efficiency of the process and requires effective methods to remove or minimize these deposits.
Innovation Solution
A capacitively coupled plasma processing method that involves cooling the upper electrode and applying a negative bias voltage during etching, utilizing a processing gas containing carbon, hydrogen, and fluorine to efficiently etch the deposits, while also measuring the electric current to detect the amount of deposit on the electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If plasma etching is performed using a hydrogen-containing gas and a fluorine-containing gas, then silicon oxide can be etched effectively, but deposits accumulate on the upper electrode reducing process efficiency
Solution Approach 1:
The patent applies a negative bias voltage to the upper electrode, changing the electrical parameter to accelerate positive ions toward the electrode surface. This enables the etching of carbon-containing deposits through ion bombardment, resolving the contradiction by maintaining etching efficiency while removing harmful deposits
Solution Approach 2:
The patent converts the harmful deposit accumulation into a beneficial process by using the deposits as a target for ion bombardment. The same plasma environment that causes deposit formation also enables deposit removal through controlled ion acceleration by negative bias voltage, transforming the harmful effect into a self-cleaning mechanism
2Object-generated harmful factors
If the upper electrode is cooled during etching, then chemical species capable of etching deposits are increased, but the process complexity increases
Solution Approach 1:
The patent employs a self-service cooling mechanism where the upper electrode itself serves as the cooling element. By integrating the cooling function directly into the electrode structure, the system avoids additional external cooling equipment, thus reducing overall system complexity while effectively increasing chemical species for deposit etching
3Object-generated harmful factors
If a negative bias voltage is applied to the upper electrode, then positive ions are accelerated toward the electrode to etch deposits, but energy consumption increases
Solution Approach 1:
The patent applies the negative bias voltage continuously during the plasma etching process, ensuring that deposit removal occurs simultaneously with the main etching operation. This continuous action maximizes the utility of the energy input by performing dual functions (substrate etching and electrode cleaning) in the same time frame, reducing overall energy waste
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 method effectively reduces or removes the deposits from the upper electrode, enhancing the plasma etching process by increasing the chemical species capable of etching the deposits and maintaining process efficiency.
Implementation Method 1
cooling an upper electrode of the plasma processing apparatus in which a chamber incorporating therein a supporting table including a lower electrode is provided and the upper electrode is provided above the supporting table
Implementation Method 2
the gas within the chamber is excited into plasma by a high frequency electric field formed between the upper electrode and the lower electrode
Implementation Method 3
since the negative bias voltage is generated in the upper electrode, positive ions in the plasma are accelerated toward the upper electrode
Implementation Method 4
an amount of chemical species capable of etching a deposit is increased around the upper electrode, so that the deposit adhering to the upper electrode is efficiently etched
Data Source
AI summary
A plasma processing method capable of reducing an amount of deposit adhering to an upper electrode or removing the deposit from the upper electrode is provided. In the plasma processing method, the upper electrode of a capacitively coupled plasma processing apparatus is cooled. A supporting table including a lower electrode is provided within a chamber of the plasma processing apparatus. The upper electrode is provided above the supporting table. During the cooling of the upper electrode, a film of a substrate is etched by plasma generated within the chamber. The substrate is placed on the supporting table during the etching of the film. A negative bias voltage is applied to the upper electrode while the etching is being performed.