Semiconductor Wafer Back Grinding for Rigidity
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Solution Overview
Problem
Semiconductor wafers with extremely thin thickness (50 μm or smaller) suffer from low rigidity, making them difficult to handle and prone to damage during additional treatments like thin metal film application and via hole formation, due to the need for downsizing and weight reduction.
Innovation Solution
Grind the back of the wafer corresponding to the device region to form a circular concavity, maintaining a thicker surplus region for rigidity, followed by additional treatments and subsequent flattening or removal of the surplus region to create a flat surface for easy handling and separation of semiconductor devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the thickness of the wafer is rendered very small (50 μm or smaller) for downsizing and weight reduction, then the weight and size of the semiconductor device are reduced, but the rigidity of the wafer is markedly low, making it difficult to handle and increasing the risk of damage
Solution Approach 1:
The patent applies local quality by creating a concave portion in the back surface of the wafer at the device region, while maintaining a thicker surplus region at the outer peripheral edge. This localized thickness variation allows the device region to achieve the required thin profile for weight reduction, while the surplus region provides structural support and rigidity for safe handling during processing.
Solution Approach 2:
The wafer back surface is segmented into two distinct regions: a device region with reduced thickness forming a concave portion, and a surplus region at the outer periphery maintaining original thickness. This segmentation allows each region to serve its specific function - the concave device region for lightweighting and the thicker surplus region for mechanical strength.
2Weight of moving object
If the thickness of the wafer is rendered very small (50 μm or smaller) for downsizing, then the weight of the semiconductor device is reduced, but the wafer becomes difficult to handle during additional treatment and the risk of damage is incurred
Solution Approach 1:
By creating a localized concave portion in the device region while preserving the original thickness at the surplus region, the patent enables the thin device region to achieve weight reduction goals while the thicker surplus region provides the mechanical strength needed for easy handling during additional treatments such as metal film formation and via hole creation.
3Manufacturing precision
If the entire back of the wafer is ground to decrease the entire thickness, then the thickness is reduced to required value, but the rigidity of the wafer is markedly low
Solution Approach 1:
Instead of uniformly grinding the entire back surface, the patent selectively grinds only the device region to create a concave portion with the required thin thickness, while leaving the surplus region at the outer periphery with sufficient thickness to maintain overall wafer rigidity and structural integrity.
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 enhances the wafer's rigidity, allowing for safer and more manageable additional treatments while achieving the goals of downsizing and weight reduction, reducing the risk of damage and facilitating the separation of semiconductor devices.
Implementation Method 1
grinding a region in the back of the wafer corresponding to the device region to form a circular concavity
Data Source
AI summary
A processing method for a semiconductor wafer which is generally circular, and which has on the face thereof an annular surplus region present in an outer peripheral edge portion of the face, and a circular device region surrounded by the surplus region, the device region having many rectangular regions defined by streets arranged in a lattice pattern, each of the rectangular regions having a semiconductor device disposed therein. The processing method includes a back grinding step of grinding a region in the back of the wafer corresponding to the device region to form a circular concavity in the back of the wafer corresponding to the device region.