Saw Bow Break Point Design for Plasma Dicing
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Solution Overview
Problem
Modern dicing techniques such as stealth dicing and plasma dicing in integrated circuit manufacturing do not guarantee a clean break of the saw bow connection, leading to potential shorting and exposure of circuit paths, which compromises the security and integrity of the semiconductor device dies during singulation.
Innovation Solution
The saw bow conductors are designed to have varying tensile strengths along their length, with a narrower region closer to the device die and a wider region closer to the neighboring die, ensuring that the break occurs in a predictable location away from the device die, thus preventing exposure of conductors on the die side.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If stealth dicing or plasma dicing is used to singulate device die, then smaller scribe lines and higher wafer density are achieved, but the saw bow connection cannot be cleanly broken and circuit paths may be exposed
Solution Approach 1:
The saw bow conductor is designed with non-uniform cross-sectional dimensions along its length, creating regions of different tensile strength. Specifically, the conductor has a first region with larger cross-sectional area providing higher tensile strength, and a second region with smaller cross-sectional area providing lower tensile strength. This local variation in structural properties ensures that the conductor breaks at the predetermined second region during plasma or stealth dicing, preventing exposure of circuit paths while enabling high wafer density.
2Ease of manufacture
If the saw bow is designed with uniform strength, then manufacturing is simpler, but the break location cannot be predictably controlled
Solution Approach 1:
The conductor is fabricated with intentionally non-uniform cross-sectional dimensions at specific locations. The first region has a larger cross-sectional area while the second region has a smaller cross-sectional area, creating a predetermined weak point. This local structural differentiation is achieved through standard photolithography and deposition processes, maintaining ease of manufacture while enabling precise control of the break location during subsequent dicing operations.
Solution Approach 2:
The conductor is pre-configured with varying tensile strength along its length before the dicing process. By creating the weak point in advance during conductor formation, the break location is predetermined and controlled, eliminating the need for complex real-time control during dicing while ensuring reliable separation of the saw bow connection.
3Reliability
If the conductor breaks close to the device die, then the saw bow connection is severed, but exposed conductors may short circuit on the die side
Solution Approach 1:
The conductor is designed with a predetermined break location in the second region that is positioned away from the device die. The non-uniform cross-sectional dimensions ensure breaking occurs at this specific location, creating a clean separation that prevents conductor exposure on the die side and eliminates the risk of short circuits, while still achieving complete isolation of the test circuitry.
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 design ensures that the saw bow breaks in a controlled manner, avoiding shorts and maintaining the security of the internal circuitry by ensuring no exposed conductors on the die side, allowing for narrower dicing lanes and increased wafer density without compromising the integrity of the semiconductor devices.
Implementation Method 1
the first conductor is formed such that a first region of the first conductor located nearer to the first semiconductor device die in the dicing lane has a lower tensile strength than a second region of the first conductor located nearer to the second semiconductor device die
Data Source
Figure 1
Figure 2A~2C
Figure 3A~3B
AI summary
A saw bow is provided and designed such that the conductors of the saw bow will break at a predictable location when using modern dicing techniques. This results in a break in the circuit provided by the saw bow, with any exposed conductors not being on the die side. Further, by providing a known breaking point in the saw bow, modern dicing techniques such as plasma dicing can be used, thereby allowing for the saw lane to be made narrower, which will in turn increase the number of wafers that can be included on a wafer.