Polonium Filter Element for Alpha Emission Reduction in Tin Plating
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The semiconductor industry faces challenges in reducing alpha particle emissions from plating baths used in the fabrication of conductive elements, particularly due to the presence of trace amounts of alpha particle emitting species like Polonium (Po) in lead-free solder materials, which are costly and can cause soft errors in semiconductor devices.
Innovation Solution
A plating tool equipped with a filter element specifically designed to filter out Polonium (Po) from the plating bath, utilizing techniques such as pulse plating with current or potential control, and reverse plating to selectively plate Tin (Sn) while suppressing the deposition of Po, and using a filtering cathode to accumulate and remove Po from the plating solution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If low alpha particle emitting electrically conductive materials are used, then soft errors in semiconductor devices are reduced, but the cost increases 2-7 times compared to standard materials
Solution Approach 1:
The patent extracts and removes alpha particle emitting species (Polonium) from the plating bath through filtration, allowing the use of standard low-cost Tin materials while achieving low alpha emission in the final plated product. The filter element selectively removes harmful Po species from the plating solution, resolving the contradiction between material cost and soft error reduction.
2Ease of manufacture
If standard Tin (Sn) materials are used in plating baths, then manufacturing cost is reduced, but alpha particle emissions cause soft errors in semiconductor devices
Solution Approach 1:
The patent introduces a filter element as an intermediary component between the plating bath and the substrate. This filter selectively removes alpha particle emitting Polonium species from the plating solution, allowing standard Tin materials to be used while preventing harmful alpha emissions from reaching the plated product, thus resolving the contradiction between cost and reliability.
3Manufacturing precision
If pulse plating with current or potential control is used, then selective deposition of Tin is improved while Polonium deposition is suppressed, but process complexity increases
Solution Approach 1:
The patent employs pulse plating with periodic current or potential control to achieve selective deposition. By applying periodic pulses rather than continuous current, the process preferentially deposits Tin while suppressing Polonium deposition, utilizing the different electrochemical properties of the two species under pulsed conditions.
4Reliability
If reverse plating is used to accumulate and remove Polonium, then alpha particle emissions are reduced, but additional processing time is required
Solution Approach 1:
The patent implements reverse plating as a preliminary action before final substrate plating. By first accumulating Polonium on a sacrificial electrode through reverse plating, the harmful species is removed from the plating bath beforehand, preventing its deposition on the substrate and reducing alpha particle emissions in the final product.
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 effectively reduces alpha particle emissions by selectively removing Po from the plating bath, allowing for the use of low-cost, non-alpha particle emitting Sn alloys, thereby enhancing the reliability and cost-effectiveness of semiconductor device fabrication while minimizing alpha particle-induced errors.
Implementation Method 1
The filter includes a Polonium (Po) filter element that filters Po
Implementation Method 2
Formation of integrated circuit structures of a semiconductor device may utilize plating processes. During plating, a metal or other electrically conductive material is plated from an exposed surface
Data Source
AI summary
A non alpha controlled plating bath including Tin species and a trace amount of Polonium species is utilized in a plating tool. The plating tool includes a Polonium filter element to remove Polonium species from the plating bath to selectively plate Tin upon a plating cathode. The filter may include a Titanium inner portion surrounding by a stannic oxide exterior. The filter may reduce the Polonium species by having the polonium absorb and then enter within the stannic oxide matrix. The filter may be located within the plating tool reservoir or filter housing. The filter may be fabricated by forming Tin upon a Titanium backbone and converting the Tin to stannic oxide.