Ohmic Electrode Contact Resistance Reduction via Etching Sequence
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Solution Overview
Problem
Existing semiconductor device manufacturing techniques fail to adequately reduce contact resistance of ohmic electrodes during the etching process, leading to increased contact resistance and limitations in cost reduction, miniaturization, ease of manufacture, resource efficiency, usability, and durability.
Innovation Solution
A method involving the formation of a semiconductor device where a plurality of metal layers are stacked, with a distinct metal layer etched from the top before heat treatment, using chlorine-containing gases for dry etching, and specific metals like titanium, aluminum, and palladium to reduce contact resistance, while ensuring the outermost layer's resistance to etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heat treatment is performed before etching to form the ohmic electrode, then the metals in the electrode layers are alloyed and adhesion is improved, but the contact resistance increases due to etching damage
Solution Approach 1:
The patent performs etching before heat treatment, reversing the conventional sequence. By removing the aluminum layer first, the subsequent heat treatment alloys the remaining metal layers (titanium, vanadium, palladium, gold) without exposing the ohmic electrode to etching damage, thus maintaining low contact resistance while achieving good adhesion through alloying
2Reliability
If multiple metal layers are stacked to form the ohmic electrode, then adhesion and electrical properties are improved, but the manufacturing complexity increases
Solution Approach 1:
The ohmic electrode is divided into multiple functional layers: titanium layer for initial adhesion, vanadium layer for electrical contact, aluminum layer for low resistance (removed by etching), and palladium/gold outer layers for protection. Each layer serves a specific function, allowing optimization of adhesion and electrical properties while managing complexity through systematic layer assignment
3Object-affected harmful factors
If the outermost layer is made of etch-resistant metal, then protection during etching is improved, but the etching process becomes less effective
Solution Approach 1:
The patent extracts the aluminum layer (which would interfere with etching) from the stack before the etching process. By removing this layer beforehand, the etching process can proceed efficiently without being hindered by etch-resistant materials, while the underlying ohmic electrode structures remain protected through the reversed process sequence
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 approach effectively minimizes contact resistance of the ohmic electrode by etching, enhancing the semiconductor device's performance, cost-effectiveness, and durability, while allowing for easier manufacturing and improved usability.
Implementation Method 1
subsequently processing the stacked electrode layers by heat treatment (annealing process, annealing to form the ohmic electrode
Implementation Method 2
the metals of the respective electrode layers are alloyed by heat treatment
Implementation Method 3
removing the another metal layer from top of the ohmic electrode by etching
Implementation Method 4
the etching may include dry etching
Data Source
AI summary
An object is to avoid an increase in contact resistance of an ohmic electrode by etching in a semiconductor device. There is provided a method of manufacturing a semiconductor device. The method of manufacturing comprises forming a semiconductor layer; forming an ohmic electrode by stacking a plurality of metal layers, on the semiconductor layer; forming another metal layer that is mainly made of another metal different from a material of an outermost layer among the plurality of metal layers, on the ohmic electrode; removing the another metal layer from top of the ohmic electrode by etching; and processing the ohmic electrode by heat treatment, subsequent to the etching.