Laser Chip Splitting with Rear Trench for Uniform Crack Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing semiconductor chip splitting methods, such as mechanical cutting and laser scribing, often result in chipping, cracking, and non-uniform cuts, leading to reliability issues and surplus material left in the split chips.
Innovation Solution
A semiconductor chip splitting method using a laser that involves forming a back-end-of-line process with wiring and trenches on the substrate, followed by laser scribing to create a scribing line, which helps in precise cutting and prevents crack propagation by forming a reformed portion with a phase transformation, thereby improving splitting properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If mechanical cutting method using dicing saw is used, then cutting process is simple, but chipping or cracking occurs on cut surface and precise cutting is difficult to ensure
Solution Approach 1:
The patent replaces the mechanical cutting system (dicing saw with diamond tip) with a laser-based system. The laser irradiates the semiconductor substrate to form a modified portion (reformed portion) through thermal effects, which then serves as a scribing line. This substitution eliminates mechanical contact that causes chipping and cracking while enabling precise cutting through controlled thermal modification and subsequent crack propagation along the predetermined path.
Solution Approach 2:
The patent changes the physical state and properties of the semiconductor substrate by irradiating it with laser energy. The laser modifies the physical properties inside the substrate, creating a reformed portion with different thermal and mechanical characteristics. This parameter change enables the substrate to be split along a precise path without mechanical contact, resolving the contradiction between cutting simplicity and cutting precision.
2Manufacturing precision
If laser scribing method is used, then cutting precision is improved, but crack may be non-uniformly formed and propagate into semiconductor chip
Solution Approach 1:
The patent performs preliminary laser irradiation to create a reformed portion (modified portion) before the actual splitting process. This reformed portion serves as a predetermined scribing line that guides subsequent crack propagation. By preparing this modified path in advance, the crack propagates uniformly along the intended trajectory rather than forming non-uniform cracks, thus improving reliability while maintaining precision.
Solution Approach 2:
The reformed portion acts as an intermediary structure between the laser irradiation and the final crack propagation. This modified region with altered physical properties serves as a controlled pathway that mediates the splitting process, ensuring cracks propagate uniformly along the predetermined path rather than randomly, thereby resolving the contradiction between precision and crack uniformity.
3Manufacturing precision
If conventional laser scribing is used, then cutting precision is improved, but unnecessary surplus material remains in split chip
Solution Approach 1:
The patent forms a lower trench at the rear surface of the semiconductor substrate before laser scribing. This preliminary action creates a predetermined separation path that guides the crack to propagate cleanly along the intended line. By preparing this lower trench in advance, the splitting process achieves precise separation without leaving unnecessary surplus material on the chip surface, thus resolving the contradiction between cutting precision and material waste.
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 enhances the reliability of the chip splitting process by preventing unnecessary surplus material and ensuring uniform crack generation, reducing defects in the split semiconductor chips.
Implementation Method 1
A method using a laser irradiates a laser to partially modify a physical property inside a semiconductor substrate
Implementation Method 2
forming a reformed portion with a phase transformation
Implementation Method 3
uses the modified portion as a scribing line and applies a physical force to both sides of the scribing line to perform a cutting process
Data Source
AI summary
A semiconductor chip splitting method using a laser includes: performing a back-end-of-line (BEOL) process comprising forming wiring at or above a front surface of a semiconductor substrate; forming a lower trench at a rear surface of the semiconductor substrate; forming a laser scribing line on the semiconductor substrate along a region overlapping the lower trench; and splitting the semiconductor substrate into chips by a process comprising cutting along the laser scribing line.