Semiconductor Wafer Dicing with Crack-Guiding Scribe Structures
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Solution Overview
Problem
The dicing process for semiconductor wafers often results in cracks that can propagate towards active components, damaging them and reducing die yield, especially when using stealth dicing before grinding (SDBG) on wafers with non-aligned lattice orientations.
Innovation Solution
A crack assist structure is formed in the scribe junction of the semiconductor wafer, comprising walls that run parallel to the die region and coupled to a weak interface, such as an air gap, to guide cracks away from the active components, thereby preventing damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If stealth dicing before grinding (SDBG) is used to separate semiconductor wafers, then dicing quality is improved and debris is reduced, but cracks can form along the edges and corners of dies and propagate toward active components, damaging components and decreasing die yield
Solution Approach 1:
A crack assist structure is introduced as an intermediary element between the die and the crack propagation path. This structure includes a crack assist feature (such as a through-silicon via or trench) that provides a predetermined path for cracks to follow, redirecting them away from active components. The crack assist structure acts as a mediator that sacrifices itself to protect the die, allowing cracks to propagate through the crack assist feature rather than through the die itself.
Solution Approach 2:
The invention converts the harmful effect of crack propagation into a beneficial outcome by providing a predetermined crack path. Instead of allowing cracks to randomly propagate through the die and damage active components, the crack assist structure guides cracks along a safe path that does not interfere with die functionality. The harm of crack formation is thus transformed into a controlled process that actually protects the die.
2Ease of manufacture
If mechanical saw cutting is used to separate semiconductor wafers, then the dicing process is simple and direct, but cracks can form along the edges and corners of dies, propagating toward active components and damaging components
Solution Approach 1:
The crack assist structure serves as an intermediary that intercepts and redirects cracks before they can reach active components. This mediator element provides a safe path for crack propagation, allowing the simple mechanical saw cutting process to continue while protecting the die from damage.
Solution Approach 2:
The crack assist structure is formed in advance during wafer fabrication, before the dicing process occurs. This preliminary action ensures that when mechanical saw cutting is performed, the crack assist feature is already in place to guide and contain any cracks that may form during the cutting process, preventing them from propagating into active areas.
3Device complexity
If no crack prevention structure is used, then the device complexity is low, but cracks propagate freely toward active components, damaging components and decreasing die yield
Solution Approach 1:
The crack assist structure is a relatively simple intermediary element that can be integrated into the existing wafer structure. It includes features such as through-silicon vias or trenches that provide predetermined crack paths. This mediator adds minimal complexity while significantly improving die yield by preventing crack propagation into active components.
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 crack assist structure effectively redirects cracks through the weak interface, reducing the risk of damage to active components, improving dicing quality, and enhancing die yield by minimizing chipping at edges and corners.
Implementation Method 1
A crack assist structure is provided in a scribe line region of a semiconductor wafer. The crack assist structure can include a plurality of walls configured to guide cracks away from a die region of a semiconductor die containing active components.
Data Source
AI summary
Structures and methods for separating semiconductor wafers into individual dies are disclosed. A semiconductor wafer or panel can include a crack assist structure in a scribe junction. The crack assist structure can include a plurality of vertical walls extending at least partially through a thickness of the wafer. In some embodiments, the plurality of vertical walls can be coupled to a weak interface. The weak interface can guide cracks that form during the dicing process in a direction along the walls, away from active circuitry. After dicing, the resulting semiconductor devices can include a plurality of vertical walls extending at least partially through a thickness of the semiconductor device. Each of the plurality of vertical walls can include at least a portion extending substantially parallel to a sidewall of the semiconductor device.