LED Linear Electrode Barrier Metal Layer Diffusion Control
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Solution Overview
Problem
Conventional semiconductor light emitting devices face inefficiencies in light emission due to opaque pad electrodes, which shield or absorb light, and the use of current confined path type LEDs partially addresses this but is limited by metal deposition issues during thermal alloying, affecting bonding strength and light gathering efficiency.
Innovation Solution
Incorporating a barrier metal layer within the pad and linear electrodes to prevent diffusion migration of components like Ge or Zn, allowing for a thinner linear electrode width and maintaining Schottky characteristics, thereby enhancing light extraction and device brightness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a linear electrode with Ge or Zn is used to improve ohmic contact, then electrical contact quality improves, but metal deposits on the pad electrode during thermal alloying, weakening bonding strength
Solution Approach 1:
The electrode structure is segmented into distinct functional layers: the linear electrode contains Ge or Zn for ohmic contact, while the pad electrode is separated by a barrier metal layer that prevents metal deposition. This segmentation isolates the problematic metal elements from the bonding wire contact area, maintaining both electrical contact quality and bonding strength.
Solution Approach 2:
A barrier metal layer is introduced as an intermediary between the linear electrode and the pad electrode. This intermediate layer acts as a diffusion barrier that prevents Ge or Zn from migrating to the pad electrode during thermal alloying, thereby protecting the bonding wire attachment point while allowing the linear electrode to maintain its electrical function.
2Productivity
If the linear electrode width is increased to improve light gathering efficiency, then light extraction improves, but the electrode shields more light and reduces luminous efficiency
Solution Approach 1:
The optimal width of the linear electrode is determined by changing the geometric parameters to balance two opposing effects: a wider electrode gathers more light (improving light gathering efficiency) but also shields more emitted light (reducing luminous efficiency). The patent identifies and implements the optimal width parameter that maximizes overall device performance by balancing these competing factors.
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 metal deposition issues, maintains bonding strength, and allows for a narrower linear electrode width, resulting in improved light extraction and increased brightness of the LED device.
Implementation Method 1
a barrier metal layer within the pad electrode and the linear electrode, the barrier metal layer covering part of or all of an upper surface and a sidewall of the linear electrode at a contact area between the linear electrode and the pad electrode
Implementation Method 2
forming an ohmic contact with the topmost semiconductor layer
Implementation Method 3
making contact with part of the pad electrode, and forming an ohmic contact with the topmost semiconductor layer
Data Source
AI summary
A semiconductor light emitting device can be configured to prevent diffusion migration of components constituting a linear electrode. The semiconductor light emitting device can include a substrate, at least one semiconductor layer formed on the substrate and having a topmost semiconductor layer, a pad electrode formed from a plurality of layers provided on the topmost semiconductor layer, and a linear electrode provided on the topmost semiconductor layer. The linear electrode can be configured to overlap the topmost semiconductor layer except for an area occupied by the pad electrode. The linear electrode can also be configured to make contact with part of the pad electrode, and form an ohmic contact with the topmost semiconductor layer. The pad electrode can include, as one of the plurality of layers, a barrier metal layer that covers part of or all of an upper surface and/or a sidewall of the linear electrode at a contact area between the linear electrode and the pad electrode.