Contact Oxide Cleaning with Dual-Frequency RF Selectivity
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Solution Overview
Problem
During wafer level packaging processes, polymer materials used in semiconductor substrates tend to oxidize and sputter back onto contacts during cleaning, interfering with the cleaning process and increasing contact resistance.
Innovation Solution
A method involving dual-frequency RF power supplies to control ion energy and density of inert gas ions for selective removal of oxide from contacts, inhibiting polymer sputtering and re-contamination, with specific frequency and power level adjustments to enhance oxide removal over polymer material removal, and process conditions such as temperature and pressure control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional cleaning processes are used to remove oxide from contacts, then oxide removal is achieved, but polymer material sputters back onto contacts causing re-contamination
Solution Approach 1:
The patent applies parameter changes by utilizing dual-frequency RF power supplies to independently control ion energy and ion density. By adjusting the first RF frequency to increase ion energy and the second RF frequency to increase ion density, the process achieves selective oxide removal while minimizing polymer sputtering. This resolves the contradiction by changing the physical parameters of the plasma environment to favor oxide removal over polymer damage.
Solution Approach 2:
The patent implements dynamics by making the ion energy and ion density adjustable and independent through dual-frequency RF control. The system can dynamically optimize the balance between oxide removal rate and polymer sputtering suppression by varying the power levels of the two RF frequencies, allowing adaptive control to resolve the contradiction between cleaning effectiveness and polymer protection.
2Productivity
If ion density is increased to improve oxide removal rate, then cleaning efficiency increases, but polymer sputtering also increases causing re-contamination
Solution Approach 1:
The patent applies segmentation by separating the control of ion energy and ion density into two independent RF frequency channels. The first RF frequency controls ion energy while the second RF frequency controls ion density. This segmentation allows the process to increase ion density for higher oxide removal rates without proportionally increasing polymer sputtering, as the ion energy can be independently optimized to favor oxide removal.
Solution Approach 2:
The patent uses parameter changes by introducing a second RF frequency parameter to independently control ion density. By adjusting the power level of the second RF frequency, the process can increase ion density to improve oxide removal rate while the first RF frequency maintains ion energy at levels that minimize polymer sputtering, thus resolving the contradiction between productivity and harmful effects.
3Manufacturing precision
If ion energy is increased to enhance oxide removal selectivity, then cleaning selectivity improves, but polymer material damage increases
Solution Approach 1:
The patent implements dynamics by making ion energy independently adjustable through the first RF frequency while maintaining polymer protection. The dynamic control allows the process to optimize ion energy for oxide removal selectivity without permanently compromising polymer integrity, as the elevated ion energy is applied only during the controlled cleaning window when oxide removal is the primary objective.
Solution Approach 2:
The patent applies segmentation by dividing the RF power control into two independent channels: one for ion energy and one for ion density. This segmentation allows ion energy to be increased for enhanced oxide removal selectivity while the ion density channel maintains conditions that protect polymer material, resolving the contradiction between cleaning precision and material integrity.
4Reliability
If cleaning process is intensified to reduce contact resistance, then electrical performance improves, but polymer sputtering increases causing re-contamination
Solution Approach 1:
The patent applies parameter changes by using dual-frequency RF power supplies to create a plasma environment where ion energy and ion density are independently optimized. This allows the cleaning process to be intensified for better contact resistance reduction while the parameter balance prevents excessive polymer sputtering, resolving the contradiction between electrical performance and polymer protection.
Solution Approach 2:
The patent implements dynamics by enabling real-time adjustment of ion energy and ion density through dual-frequency RF control. The process can dynamically intensify cleaning to reduce contact resistance while maintaining the ion energy-to-density ratio that minimizes polymer sputtering, thus improving reliability without causing re-contamination.
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 contact resistance by selectively removing oxide while minimizing polymer sputtering, thereby improving the cleaning process efficiency and throughput.
Implementation Method 1
the polymer material often gets sputtered back onto the contacts, interfering with the cleaning process
Implementation Method 2
exposing the substrate to ions of an inert gas, supplying a first RF frequency of a first bias power supply to a substrate support, wherein the first RF frequency controls ion energy of the ions of the inert gas
Data Source
AI summary
A method for cleaning contacts on a substrate incorporates ion control to selectively remove oxides. The method includes exposing the substrate to ions of an inert gas, supplying a first RF frequency of a first bias power supply to a substrate support, supplying a second RF frequency of a second bias power supply to a substrate support, and adjusting a first power level of the first RF frequency and a second power level of the second RF frequency to selectively remove oxide from at least one contact on the substrate while inhibiting sputtering of polymer material wherein the oxide removal is selective over removal of polymer material surrounding the at least one contact.