P-type Ohmic Contact in Group-III Nitride Semiconductors
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Solution Overview
Problem
Forming a reliable p-type ohmic contact in group-III nitride semiconductors is challenging, particularly for p-type regions, as existing thermal diffusion methods at temperatures between 700° C.-1150° C. fail to achieve a good ohmic contact.
Innovation Solution
A semiconductor device manufacturing method involving the formation of a magnesium-containing layer on a p-type group-III nitride semiconductor layer, followed by annealing at temperatures of 1300° C. or higher to create a p+-type region with a magnesium concentration of 1E+18 cm−3 to 1E+21 cm−3, and using a protective film made of high melting point materials like aluminum nitride or boron nitride to facilitate magnesium diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermal diffusion is conducted at temperatures of 700°C-1150°C using Mg, Zn, Si, and O as p-type dopant, then the existing thermal diffusion process can be maintained, but a good ohmic contact cannot be formed in the p-type group-III nitride semiconductor layer
Solution Approach 1:
The patent changes the temperature parameter from the conventional 700°C-1150°C range to a higher range of 1300°C-2000°C. This parameter change enables magnesium atoms to diffuse effectively into the p-type group-III nitride semiconductor layer, forming a p+-type region with sufficient magnesium concentration (1E+18 cm−3 to 1E+21 cm−3) to achieve good ohmic contact, which was not possible at lower temperatures
Solution Approach 2:
The patent applies a preliminary protective film treatment before high-temperature annealing. The protective film prevents nitrogen loss and maintains structural integrity during the high-temperature process, enabling the subsequent magnesium diffusion to proceed effectively without damaging the semiconductor layer
2Reliability
If annealing temperature is increased to 1300°C or higher to form p+-type region, then magnesium diffusion and ohmic contact quality are improved, but energy consumption and process complexity increase
Solution Approach 1:
By changing the temperature parameter to 1300°C-2000°C, the patent achieves effective magnesium diffusion and p+-type region formation in a single annealing step, which improves ohmic contact quality despite increased energy consumption. The high temperature enables direct formation of the required magnesium concentration (1E+18 cm−3 to 1E+21 cm−3) without requiring multiple processing steps
3Quantity of substance
If annealing temperature is increased to 1300°C or higher, then magnesium diffusion into p-type layer is enhanced, but nitrogen loss and structural damage may occur
Solution Approach 1:
The patent applies a protective film to the semiconductor layer before high-temperature annealing. This preliminary protective action prevents nitrogen loss and maintains structural integrity during the high-temperature magnesium diffusion process, enabling the formation of p+-type region with magnesium concentration of 1E+18 cm−3 to 1E+21 cm−3 without damaging the layer structure
Solution Approach 2:
The protective film acts as an intermediary between the magnesium-containing layer and the p-type group-III nitride semiconductor layer during high-temperature annealing. It mediates the thermal process by preventing direct nitrogen loss from the semiconductor layer while allowing magnesium diffusion to proceed, thus preserving structural integrity during the concentration enhancement process
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 method effectively forms a p+-type region with high magnesium concentration, enhancing the ohmic contact quality and reducing threading dislocation density, thereby improving the semiconductor device's performance.
Implementation Method 1
In the forming a p+-type region, the p-type group-III nitride semiconductor layer is annealed at a temperature more than or equal to 1300° C. to form a p+-type region in the p-type group-III nitride semiconductor layer located immediately below the magnesium containing layer
Data Source
AI summary
There is a problem that even if impurities are made to thermally diffuse in a temperature range of 700° C.-1150° C., a good ohmic contact cannot be formed in a p-type group-III nitride semiconductor layer.Provided is a semiconductor device manufacturing method having a group-III nitride semiconductor substrate and a p-type group-III nitride semiconductor layer on the group-III nitride semiconductor substrate, including forming a magnesium containing layer on and in direct contact with the p-type group-III nitride semiconductor layer; and annealing the p-type group-III nitride semiconductor layer at a temperature more than or equal to 1300° C. to form a p+-type region which contains magnesium as an impurity in the p-type group-III nitride semiconductor layer located immediately below the magnesium containing layer.