Wafer Taper Surface for Dicing Tape Contact
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Solution Overview
Problem
The existing wafer processing methods face challenges in ensuring close contact between the dicing tape and the boundary between the recess and the annular reinforcing portion on the wafer, leading to potential cracks and reduced quality of device chips due to uneven cutting forces and dust accumulation.
Innovation Solution
A wafer processing method that forms a taper surface between the recess and the annular reinforcing portion, allowing the dicing tape to be easily brought into close contact and maintaining contact during cutting, while the annular uncut area supports the dicing tape to prevent radial forces from affecting the cutting process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the back side of the wafer is ground to form a recess with a 90-degree angle, then the rigidity of the wafer is maintained through the annular reinforcing portion, but the dicing tape cannot be brought into close contact with the boundary between the recess and the annular reinforcing portion
Solution Approach 1:
The invention replaces the 90-degree angular boundary between the recess and annular reinforcing portion with a curved transition surface. This curvature allows the dicing tape to conform to the wafer surface and maintain close contact, eliminating the gap problem while preserving the structural integrity provided by the annular reinforcing portion.
2Device complexity
If the dicing tape is not brought into close contact with the wafer boundary, then the wafer structure remains simple, but cracks may be generated near the boundary due to cutting forces
Solution Approach 1:
The curved transition surface distributes the cutting forces more evenly across the dicing tape-wafer interface, preventing stress concentration at the boundary. This eliminates crack formation while maintaining a relatively simple overall wafer structure.
3Ease of manufacture
If the dicing tape is not brought into close contact with the wafer, then the grinding process is simpler, but cutting dust may enter the space between the wafer and dicing tape and stick to the back side
Solution Approach 1:
The curved transition surface eliminates the gap between the dicing tape and wafer boundary, creating a continuous contact interface that prevents cutting dust from entering and accumulating on the back side of the wafer, while maintaining a simple grinding process.
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 ensures proper cutting along division lines by maintaining dicing tape contact and preventing wafer movement, thereby enhancing the quality and integrity of device chips by maintaining necessary strength and reducing the risk of cracks and dust accumulation.
Implementation Method 1
a dicing tape attaching step of attaching a dicing tape to the back side of the wafer
Implementation Method 2
a dividing step of cutting the wafer along the division lines from the front side of the wafer by using a cutting blade
Implementation Method 3
The chuck table has an upper surface as a holding surface for holding the wafer. Accordingly, the bottom surface of the recess formed on the back side of the wafer is in contact with the holding surface of the chuck table through the dicing tape
Data Source
AI summary
A wafer processing method for processing a wafer having devices on the front side is provided. The wafer processing method includes a back grinding step of grinding the wafer to form a recess and an annular reinforcing portion surrounding the recess on the back side of the wafer, and a dividing step of cutting the wafer along division lines formed on the front side of the wafer. In the back grinding step, a taper surface is formed between the bottom surface of the recess and the annular reinforcing portion. The taper surface is inclined with respect to a direction perpendicular to the bottom surface of the recess. In the dividing step, a cutting blade is lowered to start cutting at a position radially inside the outer circumference of the wafer and is subsequently raised to stop cutting at another position radially inside the outer circumference of the wafer.