Lifter Pin Insulation for Plasma Discharge Prevention
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Solution Overview
Problem
In semiconductor device manufacturing, discharges can occur between the semiconductor wafer and the conductive metal base material of the lower electrode, leading to reduced yield and productivity due to potential differences and changes in pressure within through-holes of lifter pins during plasma processing.
Innovation Solution
A plasma processing method using a configuration with lifter pins having an insulating lid part and through-holes with insulating material coatings, which blocks the upper portion of the pin body receiving part when lowered, preventing discharge and maintaining consistent pressure, and an electrical connection mechanism with a current control element to manage potential differences between the focus ring and the base material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the withstanding voltage between the semiconductor wafer and the base material of the lower electrode is increased to prevent discharge, then discharge prevention is improved, but it becomes difficult to increase the withstanding voltage due to through-holes in the lower electrode where lifter pins are disposed or gas supply holes are formed
Solution Approach 1:
An insulating coating is introduced as an intermediary layer between the conductive base material of the lower electrode and the semiconductor wafer. This insulating coating fills or lines the through-holes and gas supply holes, preventing direct conductive paths that would cause discharge. The insulating material acts as a mediator that blocks electrical discharge while allowing the lower electrode structure to maintain its functional through-holes for lifter pins and gas supply.
2Temperature
If a helium gas for cooling is introduced into the through-holes of lifter pins, then cooling effectiveness is improved, but the pressure in the through-holes changes, increasing the risk that a discharge occurs according to Paschen's Law
Solution Approach 1:
The insulating coating serves as a mediator that lines the through-holes of the lifter pins, allowing helium gas to flow through for cooling while preventing the gas pressure changes from causing discharge. The insulating layer isolates the conductive surfaces, so even when pressure changes occur during gas introduction, the electrical discharge path is blocked by the insulating coating.
3Reliability
If the outer diameter of the lid part is made greater than the outer diameter of the pin body part, then the lid part can effectively block the upper portion of the pin body receiving part to prevent discharge, but the lifter pin structure becomes more complex
Solution Approach 1:
The lifter pin is segmented into two distinct parts: a pin body part that inserts into the through-hole for mechanical support and lifting function, and a lid part with a larger outer diameter that remains outside the through-hole to provide electrical insulation and block discharge paths. This segmentation allows each part to fulfill its specific function while together they solve the discharge prevention problem.
Solution Approach 2:
The solution moves from a one-dimensional approach (increasing voltage tolerance) to a two-dimensional approach by adding the lid part that extends radially outward from the pin body. This dimensional change creates a physical barrier against discharge without requiring changes to the electrical voltage parameters.
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
Prevents discharges between the semiconductor wafer and the base material, improving yield and productivity by maintaining a stable potential difference and reducing the risk of arcing, while allowing for effective plasma processing.
Implementation Method 1
a pin body receiving part, which has an inner diameter less than the outer diameter of the lid part, has an inner surface covered with an insulating material
Implementation Method 2
since a plus voltage of about +2000 to +2500 V is applied to an electrode of an electrostatic chuck, polarization charges are generated between the electrode of the electrostatic chuck and a base material
Implementation Method 3
a capacity-coupled plasma processing apparatus where the holding stage in the processing chamber serves as a lower electrode and plasma is generated by applying high-frequency power between the holding stage and an upper electrode
Implementation Method 4
a pressure in the through-holes in which the lifter pins are disposed is changed, for example, when a helium gas for cooling is introduced into the through-holes, thereby increasing the risk that a discharge occurs according to Paschen's Law
Data Source
AI summary
A method of manufacturing a semiconductor device is provided by performing plasma processing on a substrate to be processed by using a plasma processing apparatus including a processing chamber, a lower electrode, an upper electrode, a plurality of lifter pins, a focus ring, a lifter pin for focus ring and an electrical connection mechanism.