Plasma Processing Electrode Discharge Prevention
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Solution Overview
Problem
In plasma processing apparatuses, the high potential difference between a semiconductor wafer and the lower electrode leads to discharges, damaging chips and reducing production yield and productivity, as increasing the withstand voltage is challenging due to structural limitations like openings for lift pins and gas supply.
Innovation Solution
A plasma processing apparatus with an electrical connection mechanism between the lower electrode's base and the focus ring, using a current control element to generate a DC current based on the potential difference, reducing the potential difference and preventing discharges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the withstand voltage between the semiconductor wafer and the lower electrode is increased to about 5000 V to prevent discharge, then discharge prevention is improved, but it becomes difficult to achieve due to structural limitations such as openings for lift pins and gas supply openings
Solution Approach 1:
An insulating coating is applied to the lower electrode base to serve as an intermediary layer that increases the withstand voltage. This coating acts as a mediator between the conductive base and the plasma environment, providing electrical insulation without requiring structural modifications to the electrode itself, thus maintaining ease of manufacture while improving discharge prevention
Solution Approach 2:
The electrical properties of the lower electrode base are changed by applying an insulating coating with specific dielectric properties. This parameter change increases the withstand voltage from the original level to about 5000 V, enabling discharge prevention while keeping the base structure unchanged
2Power
If a high frequency power is applied to the lower electrode base to generate plasma, then plasma generation is improved, but a potential difference of about 4000 V is generated between the semiconductor wafer and the lower electrode, leading to discharge and chip damage
Solution Approach 1:
The insulating coating on the lower electrode base serves as a mediator that allows high frequency power to be applied for plasma generation while preventing the harmful potential difference from causing discharge. The coating isolates the conductive base electrically, enabling power application without direct contact between the high potential base and the wafer
Solution Approach 2:
The potential difference that originally caused harmful discharge is converted into a beneficial effect by the insulating coating, which uses this potential difference to maintain plasma generation while preventing damage. The coating transforms the harmful high voltage into a controlled plasma source
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 solution effectively prevents discharges between the semiconductor wafer and the lower electrode, increasing production yield and productivity by reducing the potential difference and maintaining plasma process uniformity.
Implementation Method 1
an electrostatic chuck for electrostatically attracting a semiconductor wafer is provided at the lower electrode
Implementation Method 2
a capacitively coupled plasma processing apparatus for generating a plasma by applying a high frequency power between a lower electrode also serving as a mounting table (susceptor) for mounting thereon a semiconductor wafer and an upper electrode disposed to face the lower electrode
Data Source
AI summary
A plasma processing apparatus includes a processing chamber; a lower electrode provided in the processing chamber and having a base made of a conductive metal to which a high frequency power is applied, the lower electrode also serving as a mounting table for mounting thereon a target substrate; an upper electrode provided in the processing chamber to face the lower electrode; and a focus ring disposed above the lower electrode to surround the target substrate. An electrical connection mechanism is provided between the base of the lower electrode and the focus ring to electrically connect the base of the lower electrode to the focus ring through a current control element, and generates a DC current in accordance with a potential difference.