Discrete Backside Metal Deposits for Die Separation Peeling
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Solution Overview
Problem
The existing methods for separating semiconductor wafers, such as sawing or scribing, often damage the metal backside (BM) layer, leading to burrs, delamination, and misalignment of die, which affects the quality and reliability of integrated circuits, especially as die sizes shrink and the tackiness of dicing tape increases.
Innovation Solution
The introduction of discrete metal deposits on the backside of semiconductor wafers adjacent to metal traces and contacts, which are not contiguously connected to the active device regions, helps in reducing mechanical damage during the dicing process by increasing the surface area of contact with adhesive tape, thereby minimizing burrs and delamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If sawing or scribing techniques are used to separate die, then die separation is achieved, but the metal backside layer is damaged causing burrs and delamination
Solution Approach 1:
The patent introduces discrete metal deposits that are segmented and not contiguously connected to each other or to the active device regions. This segmentation allows the metal layer to accommodate mechanical stress during die separation without causing delamination or burrs, while still providing adequate electrical connection points.
Solution Approach 2:
The patent applies metal deposits with specific local properties - they are discrete, non-contiguous structures positioned at specific locations away from active device regions. This local quality modification allows the metal layer to have different mechanical and electrical properties in different regions, preventing damage during separation while maintaining functionality.
2Productivity
If die size is reduced to increase integration density, then more die per wafer are produced, but the incidence of metal damage increases
Solution Approach 1:
By using segmented, discrete metal deposits rather than continuous metal layers, the patent enables smaller die sizes without proportionally increasing metal damage. The segmented structure reduces the total metal area that could potentially delaminate or form burrs, while still providing sufficient electrical connections for each die.
Solution Approach 2:
The patent changes the geometric parameters of the metal structure from continuous to discrete deposits, and positions them away from active regions. This parameter change allows smaller die sizes to be produced with reduced metal damage incidence, as the non-contiguous metal deposits require less area and are less prone to damage during separation.
3Strength
If tape tackiness is increased to secure smaller die during dicing, then die attachment is improved, but mechanical damage to metal increases
Solution Approach 1:
The patent modifies the local quality of the metal layer by creating discrete deposits with specific mechanical properties. These deposits have sufficient surface area and adhesion to maintain electrical connections during high-tackiness dicing processes, while their non-contiguous nature prevents stress propagation that would cause delamination or burrs.
Solution Approach 2:
The discrete metal deposits act as a cushioning mechanism beforehand - they are positioned and sized to absorb mechanical stresses during die separation and handling. This prior cushioning allows increased tape tackiness to be used for securing smaller die without proportionally increasing metal damage risk.
4Reliability
If metal deposits are made contiguously connected to improve electrical connection, then electrical conductivity increases, but mechanical damage during separation increases
Solution Approach 1:
The patent deliberately segments the metal deposits so they are not contiguously connected, creating discrete electrical connection points. While this segmentation reduces total metal area, it prevents stress propagation that would occur in continuous metal layers during die separation, thereby maintaining electrical connection quality without the mechanical damage associated with contiguous metal structures.
Solution Approach 2:
The patent changes the connectivity parameter of the metal layer from continuous to discrete non-contiguous deposits. This parameter change optimizes the balance between electrical conductivity and mechanical integrity during separation, as the discrete deposits provide sufficient electrical paths while being mechanically isolated to prevent delamination and burr formation.
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
The presence of metal deposits significantly reduces the incidence of burrs and delamination, enhancing the reliability and quality of die separation by maintaining proper alignment and reducing electrical contact resistance, thus addressing the variability and performance issues associated with smaller die sizes.
Implementation Method 1
attaching the fabricated wafer to an adhesive tape used for securing the fabricated wafer during a die separation process
Data Source
AI summary
A semiconductor wafer that includes a plurality of groups of active devices or circuits on a first side of the wafer and a patterned electrical contact on the backside of the wafer. Each group consisting of an active device or circuit is intended to be diced into a discrete chip. The backside of the wafer includes a metal layer patterned into discrete spaced-apart deposits that form an electrical contact to the semiconductor and the respective group of active devices. The deposits are not contiguously or laterally connected to each other and function to protect the metal layer from peeling or detaching from the wafer during dicing of the semiconductor wafer into chips.