Wafer Processing Method for Through-Silicon Via Electrode Exposure
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Solution Overview
Problem
The existing wafer processing methods face challenges in preventing defective processing such as chipping and cracking during the exposure of through-silicon via electrodes, due to instability caused by chemical etching removing the adhesive on the wafer's peripheral area, leading to reduced quality of device chips.
Innovation Solution
A method involving a first cutting step to form a step portion in the peripheral marginal area, followed by grinding to reduce wafer thickness without exposing the electrode, etching to project the electrode, forming an insulating film, a second cutting step to remove the non-adhesive area, and polishing to expose the electrode, ensuring the wafer remains stable throughout the process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the back side of the wafer is etched by chemical solution to expose the electrode, then the electrode can be connected to another device, but the chemical solution removes the adhesive in the peripheral area, causing the wafer to become unstable
Solution Approach 1:
The patent applies preliminary action by performing the first cutting step before etching to create a step portion that prevents the chemical solution from reaching and removing the adhesive. This advance preparation ensures that the adhesive remains intact during the etching process, maintaining wafer stability while still allowing electrode exposure.
Solution Approach 2:
The patent segments the peripheral marginal area into different zones: a first area that is cut to form a step portion and protect the adhesive, and a second area that is removed after etching. This segmentation allows the etching process to expose the electrode while preventing damage to the adhesive-bonded region, thus maintaining wafer stability.
2Ease of manufacture
If the peripheral area of the wafer is removed to prevent scattering during division, then the wafer stack can be divided safely, but the adhesive bonding becomes insufficient in peripheral areas
Solution Approach 1:
The patent performs the first cutting step in advance to create a protective step portion before any division operations. This preliminary action ensures that the adhesive bonding is preserved in the critical bonding area while still allowing safe removal of excess peripheral material for easy division.
3Volume of moving object
If the wafer is ground to reduce thickness, then the wafer thickness can be reduced to meet packaging requirements, but the electrode may be exposed prematurely before adhesive bonding is complete
Solution Approach 1:
The patent performs the first cutting step before grinding to create a step portion that will contain the grinding process. This preliminary action ensures that during grinding, the wafer thickness is reduced to the required level without exposing the electrode prematurely, as the step portion acts as a protective barrier until the adhesive bonding is complete.
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 method prevents defective processing like chipping and cracking, maintaining the quality of device chips by ensuring the wafer remains stable during polishing, even when the adhesive is partially removed by the chemical etching.
Implementation Method 1
etching the back side of the wafer by using a chemical solution
Implementation Method 2
polishing the back side of the wafer by using a polishing pad
Implementation Method 3
fixing the front side of the wafer through an adhesive to the carrier substrate
Data Source
AI summary
A wafer processing method is used in processing a wafer including a device area and a peripheral marginal area surrounding the device area. The device area has a plurality of devices and an electrode connected to each device. The wafer processing method includes the steps of cutting a first area of the peripheral marginal area, fixing the front side of the wafer through an adhesive to a carrier substrate, grinding a back side of the wafer, supplying a chemical solution to the back side of the wafer to thereby etch the wafer such that the electrode projects from the back side of the wafer, forming an insulating film on the back side of the wafer, cutting a second area of the peripheral marginal area, the second area being not in contact with the adhesive, thereby removing the second area, and polishing the insulating film.