Laser Dicing Semiconductor Wafers with Through Silicon Vias
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Solution Overview
Problem
Traditional dicing methods for semiconductor wafers, such as using dicing saws, can result in wafer collapse and are unsuitable for thin or narrow cutting lines, and conventional laser cutting techniques have low yield rates when dealing with uneven surfaces.
Innovation Solution
A method involving a two-stage laser dicing process where a first laser sintering process creates a passivation layer with inclined surfaces and a second laser stealth dicing process breaks the crystal structure internally, combined with a lateral tensile force to separate the wafer, forming protection caps and ensuring the wafer's integrity and precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional dicing saws are used to separate semiconductor devices, then the dicing process can be performed, but the semiconductor wafer may collapse when the wafer thickness is very thin
Solution Approach 1:
The patent replaces the mechanical dicing saw system with a laser-based system. The laser beam cuts through the semiconductor wafer without physical contact, eliminating the mechanical forces that cause wafer collapse. The laser energy is focused precisely along the cutting line, allowing separation of thin wafers while maintaining structural integrity of remaining wafer portions.
Solution Approach 2:
The patent changes the cutting parameter from mechanical blade contact to laser energy concentration. By controlling laser power, pulse duration, and focal position, the cutting process can be precisely controlled to separate devices without compromising wafer thickness or causing collapse. The laser parameters are adjusted based on wafer thickness and material properties.
2Productivity
If traditional cutting blades are used, then dicing can be performed, but they are no longer suitable for very narrow cutting lines
Solution Approach 1:
The laser-based dicing system replaces mechanical blades, enabling cutting lines limited only by laser beam focus rather than blade physical dimensions. The laser can be focused to extremely narrow widths, allowing precise separation lines that are much narrower than what mechanical blades can achieve. This enables higher device density and more efficient wafer utilization.
Solution Approach 2:
The patent transitions from two-dimensional blade contact cutting to three-dimensional laser energy focusing. The laser beam can be focused at different depths and angles, allowing precise control of the cutting zone. This dimensional flexibility enables narrow cutting lines with clean edges and minimal heat affected zones, achieving manufacturing precision unattainable with mechanical blades.
3Object-affected harmful factors
If conventional laser cutting technology is used, then some problems with sawing can be overcome, but yield rates are low when singulating wafers having uneven surfaces
Solution Approach 1:
The patent employs advanced laser parameter control including pulse duration, power density, and focal position adjustment to accommodate uneven wafer surfaces. The laser system can dynamically adapt to surface variations, maintaining consistent cutting quality across the entire wafer. This parameter flexibility compensates for surface irregularities that would otherwise cause cutting defects and reduce yield.
Solution Approach 2:
The patent introduces a carrier substrate as an intermediary between the uneven wafer and the laser cutting process. The carrier provides a flat, stable reference surface that allows precise laser focusing and movement. By mounting the wafer on the carrier, the laser system can accurately follow the cutting path while the carrier absorbs and compensates for wafer surface irregularities, ensuring high yield rates.
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 approach prevents wafer collapse and allows for precise separation of thin and narrow lines with improved yield rates, suitable for both thin and uneven surfaces, enhancing the dicing process efficiency.
Implementation Method 1
applying a first laser on the passivation layer to remove a part of the passivation layer and expose a part of the semiconductor wafer
Implementation Method 2
applying a second laser, wherein the second laser passes through the second surface of the semiconductor wafer and focuses at an interior portion of the semiconductor wafer
Data Source
AI summary
The present invention provides a semiconductor device, a semiconductor package and a semiconductor process. The semiconductor process includes the following steps: (a) providing a semiconductor wafer having a first surface, a second surface and a passivation layer; (b) applying a first laser on the passivation layer to remove a part of the passivation layer and expose a part of the semiconductor wafer; (c) applying a second laser, wherein the second laser passes through the exposed semiconductor wafer and focuses at an interior of the semiconductor wafer; and (d) applying a lateral force to the semiconductor wafer. Whereby, the cutting quality is ensured.