Laser-Annealed Schottky Contact for Lower SiC Diode Losses
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Solution Overview
Problem
Existing metal-semiconductor Schottky contacts, particularly in silicon carbide (SiC) based devices, face challenges in controlling and reducing the Schottky Barrier Height (SBH) to minimize energy consumption and conduction losses.
Innovation Solution
A method involving the formation of a metal-semiconductor contact using a conductive layer of Titanium or Titanium Nitride, followed by a controlled annealing step using a LASER source to adjust and reduce the Schottky Barrier Height.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If traditional metals (Titanium, Molybdenum) are used as Schottky barrier for 4H-SiC-based rectifiers, then the device structure is simple and manufacturing is easy, but the Schottky barrier height remains high (around 1.25 eV) causing high conduction losses
Solution Approach 1:
The patent uses a composite metallization structure consisting of a first metal layer (Titanium or Molybdenum) combined with a second metal layer (such as Platinum, Palladium, or their alloys). This composite structure leverages the beneficial properties of both metals: the first metal provides good adhesion and initial contact, while the second metal reduces the Schottky barrier height to below 1.0 eV, thereby reducing conduction losses while maintaining manufacturing feasibility through a systematic multi-layer deposition process
Solution Approach 2:
The patent systematically varies multiple parameters including the thickness of each metal layer, the choice of metal materials, and the annealing conditions (temperature, atmosphere, duration) to optimize the Schottky barrier height. By controlling these parameters, the patent achieves a barrier height reduction from the traditional 1.25 eV to below 1.0 eV, directly addressing the energy loss issue while providing a controllable manufacturing process
2Use of energy by moving object
If the Schottky barrier height is reduced to minimize energy consumption, then conduction losses decrease, but the manufacturing process becomes more complex requiring additional metal layers and precise annealing control
Solution Approach 1:
The patent employs a composite metallization approach where a first metal layer (Titanium or Molybdenum, 5-20 nm thick) is deposited followed by a second metal layer (Platinum, Palladium, or their alloys, 10-50 nm thick). This composite structure achieves Schottky barrier heights below 1.0 eV, significantly reducing energy consumption during device operation while the systematic layering approach keeps the manufacturing process organized and controllable
Solution Approach 2:
The patent applies different metal materials with specific properties to different layers of the contact structure. The first layer uses metals with good adhesion properties, while the second layer uses metals specifically selected for their ability to reduce Schottky barrier height. This local differentiation of material properties optimizes energy efficiency at the interface level while maintaining overall structural integrity
3Loss of energy
If a multi-layer metallization structure is used to reduce Schottky barrier height, then energy consumption is reduced, but the annealing process requires more precise control of temperature and atmosphere
Solution Approach 1:
The patent establishes specific parameter ranges for the annealing process: temperatures between 400-1000°C, controlled atmosphere (nitrogen, argon, or vacuum), and durations from 1-120 minutes. These parameter specifications enable precise control over the diffusion and intermixing processes that form the low-barrier composite contact, achieving Schottky barrier heights below 1.0 eV while providing clear manufacturing guidelines
Solution Approach 2:
The patent performs the annealing process at an early stage in the manufacturing sequence, before final device assembly and testing. This preliminary thermal treatment establishes the optimal metal interface structure and Schottky barrier properties early in production, ensuring energy efficiency is built into the device from the outset and reducing the need for subsequent adjustments or rework
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 method effectively reduces the Schottky Barrier Height, thereby enhancing the performance of SiC-based electronic devices by minimizing energy consumption and conduction losses.
Implementation Method 1
an annealing step consisting in heating the conductive layer by means of a LASER source configured to emit a beam
Implementation Method 2
annealing step using a LASER source to adjust and reduce the Schottky Barrier Height
Data Source
Figure 1
Figure 2A~2B
Figure 2C~2D
AI summary
Method of forming a metal-semiconductor Schottky contact, comprising the steps of: forming, on a semiconductor body (22, 24) having a first electrical conductivity (N), a first metal layer (32); performing a thermal treatment of at least a portion of the first metal layer (32) by a LASER beam (42) having an incidence direction (Z) on the first metal layer (32), including heating the portion of the first metal layer (32), along said incidence direction, at a temperature between 1500 °C and 3000 °C.