Thin Wafer Boundary Reinforcement for Breakage and Chipping
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Solution Overview
Problem
As semiconductor wafers become thinner, the stress at the boundary between the rim and membrane portions increases, leading to defects such as breakage and chipping during manufacturing processes like plating and back surface electrode formation.
Innovation Solution
Forming a recess on the wafer surface to create a thin plate and annular protrusion, followed by applying an inorganic or organic insulating film and a metal film on the boundary, which is then partially removed to reinforce the boundary, thereby mitigating stress and preventing defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wafer thickness is reduced to improve device characteristics, then device performance is improved, but stress at the boundary portion increases causing cracks and breakage
Solution Approach 1:
A recess is formed on the wafer surface before subsequent processing steps, creating a structural feature that pre-positioned stress relief capability. This preliminary structural modification allows the wafer to better withstand boundary stresses during later plating and electrode formation processes
Solution Approach 2:
The solution transitions from a two-dimensional surface problem to a three-dimensional structural solution by forming a recess that extends into the wafer thickness direction. This dimensional change creates additional stress distribution pathways and reduces concentration at the boundary portion
2Reliability
If wafer thickness is reduced, then device characteristics are improved, but manufacturing defects such as breakage and chipping increase
Solution Approach 1:
The recess structure is formed in advance before plating and electrode formation, preparing the wafer to withstand manufacturing stresses. This preliminary structural preparation prevents defects during subsequent manufacturing steps
Solution Approach 2:
The recess acts as a stress-absorbing feature that cushions against manufacturing-induced stresses before they can cause breakage or chipping. This beforehand cushioning protects the thin wafer during vulnerable manufacturing stages
3Strength
If boundary portion is reinforced to prevent cracks, then wafer strength is improved, but wafer rigidity may be compromised
Solution Approach 1:
The recess is localized specifically at the boundary portion where stress concentration occurs, rather than uniformly modifying the entire wafer. This localized modification strengthens the boundary while preserving the overall rigidity and structural integrity of the wafer body
Data Source
AI summary
A semiconductor device manufacturing method according to the present embodiment includes forming a recess on a second surface of a wafer, the wafer including a first surface on which a semiconductor element is provided and the second surface on a side opposite to the first surface, so as to form, on the second surface, a thin plate portion and an annular protrusion portion that surrounds the thin plate portion. The present manufacturing method includes forming a first film on the second surface. The present manufacturing method includes removing a part of the first film such that at least a part of the first film remains in a boundary portion between the thin plate portion and the annular protrusion portion.