Transition Metal Layer for Selective Ohmic Contact Heating
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Solution Overview
Problem
Conventional methods for forming ohmic contacts in silicon carbide semiconductor devices face challenges such as uniform heating leading to material degradation, inefficiencies in heating processes, and difficulties in selectively heating transition metal layers due to surface unevenness, resulting in inconsistent contact resistivity and potential device property degradation.
Innovation Solution
A method involving the formation of a transition metal layer on a semiconductor substrate, followed by exposure to a hydrogen plasma atmosphere generated by microwaves, where the transition metal layer absorbs hydrogen radicals to generate heat, allowing for selective and efficient formation of an ohmic contact without heating other device components, thereby preventing material degradation and improving throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If furnace annealing is used to heat the entire semiconductor substrate uniformly, then the back surface contact electrode can be heated evenly, but the semiconductor substrate and other device components are also heated, causing material degradation and constraining process sequence
Solution Approach 1:
The patent applies local quality by making the transition metal layer have unique properties (hydrogen radical absorption capability) that enable selective heating. Only the contact electrode regions containing the transition metal layer are heated to high temperature, while other device components remain at lower temperatures, thus avoiding material degradation of the semiconductor substrate and other sensitive materials.
Solution Approach 2:
The patent changes the physical-chemical parameters of the transition metal layer by introducing hydrogen radical absorption capability. This parameter change enables the layer to generate heat locally through exothermic reactions with hydrogen radicals, achieving selective heating without requiring uniform heating of the entire substrate.
2Stability of the object's composition
If laser annealing is used with reduced spot diameter to selectively heat the contact electrode, then uniform heating of the contact electrode can be achieved, but surface unevenness and slopes cause inconsistent heating and require complex irradiation control
Solution Approach 1:
The patent applies self-service by enabling the transition metal layer to automatically generate heat through its inherent ability to absorb hydrogen radicals. The layer itself performs the heating function without requiring external laser irradiation control systems, eliminating the complexity of controlling laser spots on uneven surfaces while achieving uniform selective heating.
Solution Approach 2:
The patent replaces the mechanical laser irradiation system with a chemical mechanism (hydrogen radical absorption and exothermic reaction). This substitution eliminates the need for complex mechanical control of laser spots and enables simpler, more robust selective heating that is insensitive to surface unevenness.
3Temperature
If conventional heat treatment is used to form ohmic contact, then high temperature heating is required, but this heats the entire device causing degradation of device properties and fabrication materials
Solution Approach 1:
The patent applies local quality by confining high temperature heating to only the contact electrode regions containing the transition metal layer. Other device components are not subjected to high temperature, preventing degradation of device properties and fabrication materials while still achieving the necessary temperature for ohmic contact formation.
Solution Approach 2:
The patent introduces hydrogen radicals as an intermediary that mediates the heating process. The hydrogen radicals are absorbed by the transition metal layer, triggering exothermic reactions that generate heat locally. This intermediary enables selective high-temperature heating without directly heating the entire device.
4Loss of energy
If the thickness of the semiconductor wafer is thinned to reduce conduction loss, then conduction loss is reduced, but the wafer becomes more susceptible to cracking during handling and delivery
Solution Approach 1:
The patent applies local quality by forming a tapered shape only in specific regions (contact regions) rather than thinning the entire wafer. This localized structural modification reduces conduction loss in critical areas while maintaining sufficient thickness in other regions to prevent cracking during handling and delivery.
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 enables the formation of a silicide layer with low contact resistivity, improves heating efficiency, and prevents degradation of device properties by selectively heating the transition metal layer, even on uneven surfaces, enhancing the manufacturing process for silicon carbide semiconductor devices.
Implementation Method 1
exposing the semiconductor substrate having the transition metal layer formed thereon to a hydrogen plasma atmosphere formed by microwaves to cause the transition metal layer to generate heat
Implementation Method 2
hydrogen plasma atmosphere formed by microwaves
Implementation Method 3
by a transfer of the heat from the transition metal layer, a portion of the semiconductor substrate contacting the transition metal layer is heated
Implementation Method 4
an ohmic contact is formed by a reaction of the transition metal layer and the semiconductor substrate
Data Source
AI summary
A method of manufacturing a semiconductor device includes forming a device structure in a surface of a semiconductor substrate, forming, in a face of the semiconductor substrate, a transition metal layer that contacts the semiconductor substrate, and exposing the semiconductor substrate having the transition metal layer formed thereon to a hydrogen plasma atmosphere formed by microwaves to cause the transition metal layer to generate heat. During exposure of the semiconductor substrate to the hydrogen plasma atmosphere, a portion of the semiconductor substrate contacting the transition metal layer is heated by a transfer of the heat from the transition metal layer, and an ohmic contact is formed at an interface of the transition metal layer and the semiconductor substrate by reaction of the transition metal layer and the semiconductor substrate. When the semiconductor substrate is silicon carbide, the ohmic contact is composed of a silicide, such as a transition metal silicide.