HEMT Back Contact Trench Layout for Precise Etching and Dicing
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Solution Overview
Problem
Existing HEMT devices face challenges in manufacturing due to low etch selectivity between semiconductor heterostructure and source metal layer, leading to difficult control of etch processes, increased corrosion risk, and integration issues, as well as mechanical stress causing cracks and dislocations during wafer dicing, which lowers yield and increases costs.
Innovation Solution
A HEMT device design featuring external and internal seal rings with controlled trench formation using a single etch mask to ensure precise removal of epitaxial multilayer and substrate, combined with selective etchants to minimize mechanical stress and improve manufacturing yield and reduce costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single lithography mask is used to form both the trench through the wafer and the portion removed from the semiconductor heterostructure, then manufacturing process complexity is reduced, but etch selectivity control becomes difficult leading to low manufacturing yield
Solution Approach 1:
A sacrificial layer is introduced as an intermediary between the semiconductor heterostructure and the source metal layer. This sacrificial layer serves as a selective etch stop that enables precise control of the etching process while using a single lithography mask, thus resolving the contradiction between process simplicity and etch control precision.
2Productivity
If the source metal layer is exposed during etching to simplify the process, then manufacturing steps are reduced, but corrosion risk of the source metal layer increases
Solution Approach 1:
The sacrificial layer is deposited beforehand to cover and protect the source metal layer during the etching process. This pre-established protective layer prevents corrosion of the source metal layer while allowing the etching process to proceed efficiently, thus resolving the contradiction between manufacturing efficiency and corrosion resistance.
3Reliability
If lattice mismatch between wafer and semiconductor heterostructure is present, then device functionality is achieved, but mechanical stress causes cracks and dislocations during dicing
Solution Approach 1:
The sacrificial layer is selectively removed from specific regions (such as around the active area) to create seal rings that isolate the semiconductor heterostructure from the wafer substrate during dicing. This extraction of the sacrificial layer in strategic locations prevents stress propagation and crack formation, thus resolving the contradiction between device functionality and mechanical strength during dicing.
4Reliability
If external and internal seal rings are formed to prevent crack propagation, then device reliability during dicing is improved, but manufacturing process complexity and costs increase
Solution Approach 1:
The sacrificial layer is deposited and patterned in advance to define the seal ring structures before the dicing process. This preliminary formation of seal rings through the sacrificial layer enables crack prevention during dicing while avoiding the need for additional complex manufacturing steps, thus resolving the contradiction between device reliability and manufacturing complexity.
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 enhances manufacturing precision, reduces mechanical stress, and improves yield and reliability of HEMT devices by ensuring controlled etching and consistent trench formation, thereby lowering production costs.
Implementation Method 1
both the semiconductor heterostructure 3 and the source metal layer 6 are etched using chlorine-based etchant solutions
Data Source
AI summary
A device and method of manufacturing a device based on heterostructure, including a work body, is provided having a wafer and an epitaxial multilayer that extends on the wafer along a direction from a front surface of the wafer up to an upper surface. To form an active area, a conduction region of conductive material is formed on the epitaxial multilayer. To form a contact region for biasing the first conduction region: a front trench is formed in the work body starting from the upper surface towards the back surface of the wafer, up to a contact surface; a conductive region is formed inside the front trench, on the contact surface, and in electrical contact with the first conduction region; a back trench is formed in the work body starting from the back surface towards the upper surface up to the contact surface; and a back metallization layer is formed on the back surface of the wafer and inside the back trench, on the contact surface.