Element Chip Dicing Using Plasma Etching to Prevent Substrate Damage
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Solution Overview
Problem
The challenge in manufacturing thin multi-layered element chips, such as flash memory, lies in the difficulty of separating die attach films from substrates without damaging the substrate, especially with the increasing complexity and diversity of silicon crystal orientations and the formation of burrs during laser ablation, which complicates the dicing process and results in unstable separation and production inefficiencies.
Innovation Solution
A plasma-etching technique is employed to separate the die attach film from the substrate, where a protective film covers the substrate and die attach film, forming grooves to expose the substrate for plasma-etching, allowing for precise separation of the die attach film into pieces corresponding to individual element chips, thereby reducing contamination and production time and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the substrate thickness is reduced to achieve smaller and thinner packages, then the package size is reduced, but the substrate strength is reduced making it difficult to separate the die attach film without damaging the substrate
Solution Approach 1:
A protective film is formed on the substrate surface before the dicing and separation processes. This protective film reinforces the thin substrate structure, preventing damage during subsequent processing steps where the substrate would otherwise be too weak to withstand the separation forces applied to remove the die attach film.
Solution Approach 2:
The substrate is combined with a protective film to create a composite structure. This composite provides both the thin profile needed for small packages and the enhanced mechanical strength required to withstand the separation process, effectively resolving the contradiction between reduced thickness and maintained strength.
2Productivity
If laser ablation is used to separate the die attach film, then the separation process is achieved, but burrs are formed at the end surfaces making it difficult to have flush end surfaces and causing reconnection of separated DAF
Solution Approach 1:
The patent replaces the laser ablation process with a mechanical dicing method using a dicing saw. This substitution eliminates the burr formation problem inherent in laser ablation while achieving clean, precise cuts that provide flush end surfaces and prevent reconnection of the separated die attach film.
Solution Approach 2:
The separation method changes from thermal/optical (laser ablation) to mechanical cutting. This parameter change in the separation mechanism fundamentally alters the interaction with the die attach film, producing clean edges without the melting and burr formation characteristic of laser processes.
3Productivity
If laser irradiation is applied at positions between element chips to separate the die attach film, then the separation is achieved, but the production time increases due to the need to map chip positions
Solution Approach 1:
The patent replaces the laser-based separation method with mechanical dicing using a dicing saw. This mechanical approach can process the entire substrate simultaneously without requiring position mapping of individual chips, significantly reducing production time while achieving the same separation objective.
Solution Approach 2:
The mechanical dicing process allows continuous processing across the entire substrate in a single operation. Unlike laser methods that require sequential positioning and mapping, the dicing saw can continuously cut through the substrate along predetermined paths, eliminating downtime for position mapping and maintaining continuous productive action.
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 high-quality element chip production by preventing non-volatile material scattering, ensuring flush end surfaces, and stabilizing the dicing process, improving the yield and efficiency of the manufacturing process.
Implementation Method 1
a fifth step for plasma-etching the substrate exposed along the dicing regions within a first plasma atmosphere to form a plurality of element chips from the substrate, and to expose the die attach film, a sixth step for plasma-etching the die attach film exposed along the dicing regions within a second plasma atmosphere
Data Source
AI summary
A manufacturing process of an element chip comprises steps of preparing a substrate including dicing regions and element regions, attaching a holding sheet held on a frame with a die attach film in between, forming a protective film covering the substrate, forming a plurality of grooves in the protective film along the dicing regions, plasma-etching the substrate to expose the die attach film and then die attach film along the dicing regions, and picking up each of the element chips along with the separated die attach film away from the holding sheet, wherein the die attach film has an area greater than that of the substrate, and wherein the protective film includes a first covering portion covering the substrate and a second covering portion covering at least a portion of the die attach film that extends beyond an outer edge of the substrate.