Redistribution Line Oxide Layer for Copper Migration Prevention
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Solution Overview
Problem
Redistribution lines in semiconductor devices are prone to oxidation and electrochemical migration, which decreases the reliability of the devices due to issues such as copper diffusion and thermal damage to sensitive components like color filters and micro-lenses.
Innovation Solution
A method of forming a semiconductor device that includes growing a native metal oxide layer between the redistribution line and the passivation layer at a temperature equal to or less than 250°C, with a thickness ranging from 50 nm to 200 nm, to prevent copper migration and thermal damage, while ensuring the oxide layer does not crack and maintain electrical integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thick oxide layer is grown to prevent copper migration, then reliability improves, but the oxide layer may crack and electrical integrity deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the thickness of the oxide layer within the range of 50-200 nm and limiting the maximum temperature to 250°C during growth. This optimized parameter combination ensures sufficient thickness to prevent copper migration while maintaining integrity to avoid cracking, thus resolving the contradiction between reliability and strength.
2Manufacturing precision
If high temperature processing is used to grow the oxide layer, then oxide layer formation is effective, but thermal damage occurs to color filters and micro-lenses
Solution Approach 1:
The patent resolves this contradiction by changing the temperature parameter to a maximum of 250°C, which is sufficiently high to enable effective oxide layer growth while remaining below the thermal damage threshold of the color filters and micro-lenses. This precise temperature control allows simultaneous achievement of manufacturing precision and avoidance of thermal harm.
3Object-affected harmful factors
If the oxide layer is grown too thin, then thermal damage is avoided, but copper migration increases and reliability decreases
Solution Approach 1:
The patent addresses this contradiction by establishing a minimum oxide layer thickness of 50 nm, which provides sufficient barrier properties to prevent copper migration while maintaining compatibility with the low-temperature growth process that avoids thermal damage. This parameter optimization ensures both reliability and thermal safety.
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 solution effectively prevents copper migration and thermal damage, enhancing the reliability of semiconductor devices by maintaining the electrical integrity of redistribution lines and avoiding cracking of the oxide layer, thus ensuring stable device performance.
Implementation Method 1
spontaneously forming an oxide layer on the redistribution line, and growing the oxide layer between the redistribution line and the passivation layer
Data Source
AI summary
A method of manufacturing a semiconductor device includes providing a semiconductor substrate having a top surface, on which has been formed a color filter and a micro-lens, and a bottom surface opposite to the top surface, forming a redistribution line on the bottom surface of the semiconductor substrate, and forming on the bottom surface of the semiconductor substrate a passivation layer covering the redistribution line. After the redistribution line and passivation layer are formed, an oxide layer between the redistribution line and the passivation is formed at a temperature that avoids thermal damage to the color filter and the micro-lens.