Metallic Feature Cleaning After Plasma Dicing Under Thermal Limits
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Solution Overview
Problem
Existing cleaning methods for removing fluorine-containing contaminants from metallic features on substrates after plasma dicing processes are inadequate, particularly for temperature-sensitive carrier sheets, and fail to maintain strict thermal budgets.
Innovation Solution
A method involving alternating sputter etch and chemical etch steps using inductively coupled plasma to effectively remove fluorine-containing residues while maintaining low thermal loads, employing argon and oxygen-containing gases with controlled electrical bias powers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If sputter etching is used to remove fluorine-containing contaminants from metallic features, then cleaning effectiveness is improved, but thermal load on the substrate increases
Solution Approach 1:
The patent applies periodic action by alternating between sputter etching steps and chemical etching steps in a cyclic manner. The sputter etching step (using Ar plasma) removes fluorine-containing contaminants, followed by a chemical etching step (using O2 or O3 plasma) that cleans the surface without significant thermal load. This periodic alternation allows effective contaminant removal while managing the thermal budget through the cooler chemical etching intervals.
Solution Approach 2:
The patent employs parameter changes by varying the plasma chemistry and power conditions between different etching steps. The sputter etching uses Ar plasma with specific power settings to physically sputter contaminants, while the chemical etching switches to O2/O3 plasma with different parameters to chemically clean the surface. These parameter changes enable effective cleaning at reduced thermal loads by optimizing each step for its specific function.
2Manufacturing precision
If Ar sputter etching is used to clean bond pad surfaces, then fluorine-containing residues are removed, but the process is not suitable for temperature-sensitive carrier sheets
Solution Approach 1:
The patent uses periodic action to alternate between sputter etching (Ar plasma) and chemical etching (O2/O3 plasma) steps. The chemical etching steps serve as lower-temperature interventions between the more effective but thermally demanding sputter etching steps, making the overall process compatible with temperature-sensitive carrier sheets while maintaining effective contaminant removal capability.
Solution Approach 2:
The patent applies composite materials by combining different plasma chemistries (Ar and O2/O3) in a hybrid cleaning process. This composite approach leverages the physical sputtering capability of Ar plasma for effective contaminant removal and the chemical cleaning capability of O2/O3 plasma for surface preparation, creating a versatile process that works with temperature-sensitive carrier sheets.
3Reliability
If oxygen plasma cleaning is performed before sputter etching, then oxide films are formed, but they require additional sputter etching to remove
Solution Approach 1:
The patent inverts the conventional sequence by performing sputter etching first to remove fluorine-containing contaminants, then applying chemical etching to clean the surface. This reversal avoids the problem of forming oxide films that would require additional removal steps, as the sputter etching is performed before any significant oxidation can occur, and the subsequent chemical etching cleans without forming thick oxides requiring further sputtering.
Solution Approach 2:
The patent uses periodic action with alternating sputter and chemical etching steps, where the chemical etching step follows the sputter etching to clean the surface without allowing extensive oxide formation. This timed alternation prevents the accumulation of oxide films that would require additional removal steps, optimizing the process sequence to minimize total process time.
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
The method achieves efficient removal of fluorine-containing contaminants with reduced thermal impact, improving substrate quality and throughput by minimizing thermal damage to temperature-sensitive carrier sheets.
Implementation Method 1
performing a sputter etch step comprising the sub-steps of introducing a sputter gas or gas mixture into the chamber, and sustaining an inductively coupled plasma of the sputter gas or gas mixture so as to sputter etch the substrate
Implementation Method 2
performing a chemical etch step comprising the sub-steps of introducing O 2 gas and/or O 3 gas into the chamber, and sustaining an inductively coupled plasma of the O 2 and/or O 3 gas so as to chemically etch the substrate
Implementation Method 3
sustaining an inductively coupled plasma within a chamber of the apparatus
Data Source
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AI summary
According to the present invention there is provided a method for cleaning a metallic feature on a substrate of the type that is part of a workpiece that has been subjected to a plasma dicing process, the workpiece further comprising a carrier sheet attached to a frame member, wherein the carrier sheet carries the substrate, the method comprising the steps of: providing the workpiece on a workpiece support disposed within a chamber of an inductively coupled plasma apparatus; performing a sputter etch step comprising the sub-steps of introducing a sputter gas or gas mixture into the chamber, and sustaining an inductively coupled plasma of the sputter gas or gas mixture so as to sputter etch the substrate; performing a chemical etch step comprising the sub-steps of introducing O2 gas and/or O3 gas into the chamber, and sustaining an inductively coupled plasma of the O2 and/or O3 gas so as to chemically etch the substrate; and repeating the steps of performing the sputter etch step and performing the chemical etch step