Plasma Wafer Dicing With SF6-Ar Etching for Clean Die Edges
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Plasma dicing of semiconductor wafers using organic masks results in unwanted polymer deposition and incorporation of inorganic matter, leading to filament formation and corrosion concerns, which are difficult to remove and can damage the die.
Innovation Solution
Employing an etch chemistry of SF6 gas mixed with Ar gas for both silicon oxide and silicon etching processes, utilizing a cyclic Bosch process, to minimize polymer and inorganic deposits, followed by plasma ashing to remove the mask, thereby preventing filament formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If plasma etching is performed using conventional etch chemistry, then the etching process can be completed, but polymer deposition and inorganic matter incorporation occur on the mask and die edges
Solution Approach 1:
The patent changes the chemical parameters of the etching process by using SF6 and Ar gases instead of conventional etch chemistries. This parameter change modifies the plasma composition to reduce polymer deposition while maintaining effective etching of silicon oxide and silicon layers.
Solution Approach 2:
The patent employs a composite gas mixture of SF6 and Ar to achieve the desired etching performance. The combination of these two gases provides both the fluorine needed for silicon etching and the argon that reduces polymer deposition, creating a synergistic effect that resolves the contradiction.
2Ease of manufacture
If organic mask is used for plasma dicing, then cost is reduced by applying mask directly on silicon oxide layer, but unwanted polymer material deposits on mask sides and die adjacent to etch regions
Solution Approach 1:
The patent changes the etch chemistry parameters to SF6 and Ar gas mixture, which fundamentally alters the deposition behavior during plasma etching. This parameter change reduces polymer deposition on the organic mask and adjacent die surfaces while maintaining the cost advantage of using organic masks.
3Area of stationary object
If narrower cut is achieved through plasma dicing, then die packing density is improved, but polymer deposits and filaments remain as obstructions
Solution Approach 1:
The patent uses SF6 and Ar gas mixture to change the etching parameters, achieving narrow cuts with minimal polymer deposition. The specific gas composition allows for precise control of the etching process that reduces unwanted deposits while maintaining tight spacing between die.
4Productivity
If fluorine compounds are present in polymer deposits, then etching process can proceed, but corrosion concern arises for exposed metal areas of die
Solution Approach 1:
The patent modifies the etch chemistry parameters by using SF6 and Ar gases in specific proportions. This parameter change controls the fluorine content in the plasma, enabling effective etching while reducing fluorine incorporation in polymer deposits that could cause corrosion of metal areas.
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
Reduces polymer and inorganic residue formation, ensuring cleaner die edges and preventing corrosion, allowing for closer die packing and improved manufacturing efficiency.
Implementation Method 1
plasma etching to remove the top silicon oxide layer in the scribe line regions to expose the main silicon layer, wherein the plasma etching is performed using an etch chemistry comprising gaseous SF6 gas mixed with gaseous Ar
Implementation Method 2
the plasma etching is performed using an etch chemistry comprising gaseous SF6 gas mixed with gaseous Ar
Implementation Method 3
followed by plasma ashing to remove the mask
Data Source
AI summary
Method of plasma dicing a semiconductor wafer. The method includes a step of providing a semiconductor wafer comprising a main silicon layer and a top silicon oxide layer covered with an organic soft mask. The mask defines a plurality of scribe line regions to be etched. The method includes a step of plasma etching to remove the top silicon oxide layer in the scribe line regions to expose the main silicon layer. The plasma etching is performed using an etch chemistry having gaseous SF6 gas mixed with gaseous Ar. The method includes a step of plasma etching to remove the main silicon layer in the scribe line regions to provide a plurality of individual semiconductor die.