Wafer Singulation Precutting and Backside Cutting to Reduce Chipping
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Solution Overview
Problem
Existing singulation processes for semiconductor devices, such as mechanical sawing, lasers, and chemical etching, result in debris, chemical byproducts, and chipping, which can damage the devices and require extensive cleaning, and are inefficient in achieving clean separation.
Innovation Solution
A precutting process involving narrow openings is performed on the front side of the wafer, followed by flipping and cutting through the back side to minimize debris and damage, using techniques like plasma, lasers, or saws, ensuring minimal chipping and delamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional singulation processes (mechanical sawing, lasers, chemical etching) are used to separate semiconductor devices, then separation is achieved, but debris, chemical byproducts, and chipping are generated which damage devices and require extensive cleaning
Solution Approach 1:
The patent applies preliminary action by forming precuts in the semiconductor wafer before the final singulation step. These precuts are created at a first depth from the front surface, establishing initial separation paths that guide the subsequent final cut. This preliminary preparation enables cleaner final separation by pre-defining the fracture paths and reducing unpredictable chipping during the main singulation process.
Solution Approach 2:
The singulation process is segmented into multiple distinct steps: forming precuts at a first depth from the front surface, flipping the wafer, and performing the final cut from the back surface. This segmentation allows each step to be optimized independently - the precut formation creates controlled initial separations while the final cut completes the separation with minimal damage, avoiding the need for single-step aggressive cutting methods that generate debris.
2Manufacturing precision
If aggressive cutting methods are used to achieve complete separation, then singulation is completed, but chipping and delamination risks increase
Solution Approach 1:
The precut formation serves as preliminary action that creates controlled initial separation paths at a safe depth from the front surface. These precuts establish guided fracture paths that prevent uncontrolled chipping during the final cut. By pre-defining the separation paths, the final singulation can be performed with less aggressive forces, thereby reducing chipping and delamination risks while achieving clean separation.
Solution Approach 2:
The patent inverts the conventional singulation approach by flipping the wafer after precut formation and performing the final cut from the back surface rather than the front. This inversion allows the final cutting action to occur from the opposite side, enabling better control over the separation process and reducing the risk of chipping and delamination that would occur with traditional front-side aggressive cutting methods.
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 reduces debris and damage to semiconductor devices by protecting the front side during the final cut, minimizing chipping and delamination risks, resulting in cleaner and more efficient singulation.
Implementation Method 1
forming the first opening and the second opening includes using a plasma cutting process
Implementation Method 2
forming the first opening and the second opening includes using a laser beam
Implementation Method 3
forming the first opening and the second opening includes using a saw
Data Source
AI summary
Embodiments provide a precutting technique to cut parallel openings at a front surface of a device wafer, then flipping the device wafer over and completing the cut from the back side of the device wafer to singulate a die from the wafer. The precutting technique and back side cutting technique combined provides an indentation in the side surface(s) of the device.