Semiconductor Wafer Drying via Asymmetric Rib Design
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Solution Overview
Problem
Existing methods for manufacturing semiconductor devices face issues with foreign substances remaining after drying and stain generation, particularly due to wafer warpage and handling-related contamination.
Innovation Solution
A method involving a semiconductor wafer with a device region and a ring-shaped reinforced portion, where the center position of the wafer differs from the center position of the reinforced portion, allowing efficient water drainage during drying to prevent foreign substances and stains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the inner circumferential wall of the rib is tilted into a reverse tapered shape, then foreign substance adhesion to the thinned portion is reduced, but foreign substances adhere to the rib contacting portion and are difficult to remove
Solution Approach 1:
The patent applies asymmetry by making the inner circumferential wall of the rib tapered (inclined inward from top to bottom) rather than vertical or reverse tapered. This asymmetric shape allows water to naturally drain downward along the inclined surface during rotation, preventing foreign substances from adhering to the thinned portion while avoiding the problem of foreign substance accumulation that occurs with reverse tapered designs.
Solution Approach 2:
The patent utilizes hydraulic principles by leveraging water flow during the drying process. The tapered shape of the rib's inner circumferential wall is designed to work with water drainage during wafer rotation, allowing water to carry away foreign substances naturally without requiring additional mechanical intervention. This hydraulic approach replaces the need for complex cleaning mechanisms.
2Reliability
If carbon dioxide is added to pure water for wet treatment, then charging of grinding water is prevented, but foreign substances stay behind after drying and stains are generated
Solution Approach 1:
The patent applies parameter changes by modifying the physical state and composition of the water used in wet treatment. Instead of using pure water with carbon dioxide (which causes staining), the patent uses water containing specific concentrations of cleaning agents or surfactants that change the water's wetting properties and drying characteristics, preventing foreign substance adhesion without causing stains.
Solution Approach 2:
The patent introduces an intermediary substance (cleaning agent or surfactant) between the water and the wafer surface. This intermediary modifies the interaction between water and foreign substances, preventing foreign substances from adhering to the wafer during drying while avoiding the charging problems associated with carbon dioxide-enriched water.
3Productivity
If the wafer is thinned to 50 μm or less using ultra-thin wafer process, then cost and energization performance are improved, but wafer cracking occurs more frequently during back side processing
Solution Approach 1:
The patent applies segmentation by dividing the wafer into two distinct regions: a thinned device region (50 μm or less) for improved performance and cost, and a thickened peripheral region (rib structure) for mechanical strength. This segmentation allows the wafer to simultaneously achieve the electrical performance benefits of thinning while maintaining structural integrity through the thicker peripheral support structure.
Solution Approach 2:
The patent applies local quality by making different parts of the wafer have different thicknesses tailored to their specific functions. The central device region is thinned to 50 μm or less for optimal electrical characteristics, while the peripheral region is maintained at greater thickness to provide mechanical strength and resistance to cracking during handling and processing.
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 effectively prevents foreign substances from remaining after drying and reduces stain generation by ensuring efficient water drainage and enhanced wafer handling, thereby improving the manufacturing process.
Implementation Method 1
after the wet treatment, rotating and drying the semiconductor wafer
Data Source
AI summary
A device region (17) is formed at a central part of a semiconductor wafer (2) and a ring-shaped reinforced portion (18) which is thicker than the device region (17) is formed on an outer circumference of the device region (17). After forming the device region (17) and the ring-shaped reinforced portion (18), the semiconductor wafer (2) is subjected to wet treatment. After the wet treatment, the semiconductor wafer (2) is rotated and dried. A center position of the semiconductor wafer (2) is different from a center position of the ring-shaped reinforced portion (18).