Laser Wafer Thinning via Defect Structure Fracture
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Solution Overview
Problem
Conventional wafer grinding techniques for producing thin or ultra-thin chips introduce defects and are difficult to control, leading to yield loss and high costs, and existing methods for manufacturing ultra-thin chips through wafer pre-processing are complex and costly.
Innovation Solution
A method involving the use of a focused laser beam to create a defect structure within a wafer, separating it into a first region and a second region, where the first region remains in one piece, allowing for efficient thinning and reducing the need for mechanical handling and carrier systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If wafer grinding techniques are used to produce thin or ultra-thin chips, then wafer thinning is achieved, but defects are introduced and control is difficult leading to yield loss
Solution Approach 1:
The patent replaces the mechanical wafer grinding system with a laser-based system. The laser beam is focused at a specific depth within the wafer to create a defect structure that guides fracture, eliminating the need for mechanical contact and subsequent defect removal steps. This substitution of mechanical processing with optical processing resolves the contradiction by achieving precise thickness control without introducing mechanical defects.
Solution Approach 2:
The patent applies preliminary action by creating a defect structure within the wafer before the actual fracture occurs. The laser focuses at a predetermined depth to create this defect structure that serves as a fracture guide, allowing the wafer to break cleanly at the desired thickness without requiring post-processing defect removal. This preliminary defect creation enables controlled fracture while minimizing final defect rates.
2Manufacturing precision
If mechanical wafer treatment is used for thinning, then wafer thickness is reduced, but the process becomes difficult to control and costly
Solution Approach 1:
The patent replaces difficult-to-control mechanical thinning processes with a laser-based system where the focus depth can be precisely controlled through optical parameters. The laser wavelength, numerical aperture, and focus position determine the defect structure depth, providing straightforward control mechanisms that are easier to implement and maintain than mechanical grinding systems.
Solution Approach 2:
The patent utilizes parameter changes by adjusting laser parameters (wavelength, power, pulse duration, focus position) to control the defect structure formation and subsequent fracture behavior. By changing these optical parameters, the wafer thickness can be precisely controlled without the complexity of adjusting mechanical grinding parameters, improving ease of manufacture while maintaining manufacturing precision.
3Productivity
If conventional wafer processing methods are used, then chips can be produced, but operational costs are high due to carrier systems and mechanical handling
Solution Approach 1:
The patent extracts and eliminates the need for complex carrier systems and mechanical handling infrastructure from the wafer processing line. By using laser-induced fracture, wafers can be processed and separated without requiring specialized carrier tapes, bonding mechanisms, or complex mechanical handling systems, thereby reducing operational costs while maintaining productivity.
Solution Approach 2:
The patent enables self-service by allowing the wafer to fracture automatically along the laser-created defect structure without external mechanical intervention. The stored elastic energy in the wafer, combined with the defect structure, causes spontaneous fracture that separates the chips, eliminating the need for energy-intensive mechanical handling and carrier systems throughout the production 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 enables precise control over wafer thickness, reduces operational costs, minimizes wafer scrap, and avoids defects associated with mechanical machining, while maintaining high performance and flexibility in semiconductor processing.
Implementation Method 1
scanning a focused laser beam over the wafer to form a defect structure within the wafer
Implementation Method 2
scanning a focused laser beam over the wafer to form a defect structure within the wafer
Data Source
AI summary
According to various embodiments, a method for processing a wafer may include scanning a focused laser beam over the wafer to form a defect structure within the wafer, the defect structure defining a first region of the wafer located at a first side of the defect structure and a second region of the wafer located at a second side of the defect structure opposite the first side, and an edge region laterally surrounding the defect structure and extending from a first surface of the wafer to a second surface of the wafer opposite the first surface. A surface area of the first region is greater than a surface area of the edge region, and the second region is connected to the first region by the edge region. The method may further include, separating the first region and the second region from each other along the defect structure, with the first region remaining in one piece.