Device Wafer Division via Plasma Etching and Laser Ablation
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Solution Overview
Problem
The difficulty in dividing device wafers with adhesive films using plasma etching due to the film's resistance and the subsequent issues of burr formation and debris attachment during blade or laser processing.
Innovation Solution
A processing method involving a mask coating step with a water-soluble resin, followed by laser ablation to form grooves, plasma etching to expand the division grooves, and subsequent laser processing to divide the adhesive film, along with an additional coating and cleaning step to manage debris.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If plasma etching is used to form division grooves, then the groove width can be reduced, but the adhesive film cannot be effectively etched and requires additional blade or laser processing
Solution Approach 1:
The adhesive film is pre-coated on the back surface of the device wafer before plasma etching. This preliminary action ensures the adhesive film is in position to receive the plasma etching treatment, allowing the groove to be formed through both the substrate and adhesive film in one process, eliminating the need for subsequent blade or laser processing of the adhesive film.
Solution Approach 2:
The plasma etching parameters are optimized to achieve different etching rates for the substrate and adhesive film. By controlling plasma power, gas flow, and exposure time, the process forms grooves of controlled width in the substrate while simultaneously etching the adhesive film to a suitable depth, resolving the contradiction between groove width and adhesive film processability.
2Ease of manufacture
If blade or laser processing is used to divide the adhesive film, then the adhesive film can be cut, but burrs and debris are generated that attach to device surfaces
Solution Approach 1:
The mechanical blade cutting process is replaced with plasma etching, which is a chemical vapor phase process. This substitution eliminates mechanical contact that generates burrs and debris, replacing it with a controlled chemical reaction that deposits etched material as a fine powder that can be easily removed without attaching to device surfaces.
Solution Approach 2:
The plasma etching process utilizes phase transitions of the adhesive film material from solid to vapor phase through plasma-induced chemical reactions. This phase transition allows the adhesive film to be removed cleanly without mechanical contact, preventing burr formation and debris attachment to device surfaces.
3Length of stationary object
If plasma etching is used on the adhesive film, then groove width is reduced, but the adhesive film is more difficult to dice compared to silicon substrate
Solution Approach 1:
The plasma etching processes for the substrate and adhesive film are merged into a single continuous operation. The same plasma chamber and etching parameters are used to process both materials sequentially, eliminating the need for separate processing steps and reducing overall process complexity despite the different etching characteristics of the two materials.
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
Enables easy division of device wafers with adhesive films into individual chips while minimizing burr formation and debris attachment, improving processing efficiency.
Implementation Method 1
coating a front surface of the device wafer with a water-soluble resin as a protective mask
Implementation Method 2
applying a laser beam to the front surface of the device wafer, forming a groove along each of the division lines by ablation processing
Implementation Method 3
supplying a gas in a plasma condition to the front surface of the device wafer to form a division groove that divides the substrate along the groove
Implementation Method 4
expanding the protective tape in a plane direction to expand a width of the division groove
Implementation Method 5
applying a laser beam to the adhesive film that has been exposed due to the formation of the division groove, and dividing the adhesive film along the division groove by ablation processing
Implementation Method 6
cleaning and removing the water-soluble resin
Data Source
AI summary
A processing method of a device wafer includes a mask coating step of coating a front surface of the device wafer with a water-soluble resin, a mask forming step of applying a laser beam along each division line, forming a groove, and removing a protective mask and a functional layer to expose a substrate, a plasma etching step of forming a division groove that divides the substrate along the groove by supplying a gas in a plasma condition, an expanding step of expanding a protective tape in a plane direction to expand a width of the division groove, an adhesive film dividing step of applying a laser beam along the division groove to divide the adhesive film that has been exposed due to the formation of the division groove, and a cleaning step of cleaning and removing the water-soluble resin.