Semiconductor Field Stop Zone via Laser Irradiation
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Solution Overview
Problem
In semiconductor devices, achieving a balance between low device leakage currents, cost-effectiveness, and process compatibility is challenging due to the need for a field stop zone that absorbs voltage without increasing chip thickness, particularly in manufacturing processes involving semiconductor diodes and IGBTs.
Innovation Solution
A method involving laser irradiation of a semiconductor body with a specific oxygen concentration, followed by proton irradiation and annealing within a controlled temperature range, to create a field stop zone that reduces leakage currents and enhances dopant activation, while introducing platinum to manage minority carrier lifetime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a low doping concentration of base material is used to achieve DC voltage blocking requirement, then voltage blocking capability is improved, but chip thickness must be increased to prevent space charge zone from reaching rear-side contact region
Solution Approach 1:
The base material is segmented into two distinct zones: a low doping concentration region for voltage blocking and a high doping concentration field stop zone for space charge termination. This segmentation allows each zone to perform its specific function optimally without requiring increased overall chip thickness.
Solution Approach 2:
Different doping concentrations are applied to different regions of the semiconductor device. The field stop zone has high doping concentration localized at specific positions (drift region or junction termination extension) to terminate space charge, while the bulk base material maintains low doping concentration for voltage blocking.
2Length of moving object
If a field stop zone is introduced to reduce chip thickness, then chip thickness is reduced, but manufacturing process complexity increases due to trade-offs between leakage currents, cost-effectiveness, and temperature budget requirements
Solution Approach 1:
Conventional thermal diffusion or ion implantation methods for creating the field stop zone are replaced with laser irradiation. This substitution simplifies the manufacturing process by eliminating the need for complex temperature budget management and multiple processing steps, while achieving the same electrical field termination effect.
Solution Approach 2:
The method changes the approach to doping concentration modification by using laser-induced local melting and rapid solidification. This parameter change in the manufacturing method (from thermal/chemical processes to laser-induced phase change) simplifies process control and reduces manufacturing complexity.
3Ease of manufacture
If conventional methods are used to form field stop zone, then process compatibility is maintained, but device leakage currents increase
Solution Approach 1:
Conventional thermal diffusion or ion implantation methods are replaced with laser irradiation to form the field stop zone. This substitution eliminates the harmful effects associated with conventional methods (such as excessive leakage currents) while maintaining process compatibility through integration into existing semiconductor manufacturing workflows.
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 reduces leakage currents and suppresses undesired counter-doping effects, leading to improved device characteristics and reduced costs by optimizing the field stop zone formation in semiconductor devices.
Implementation Method 1
forming a field stop zone by irradiating a portion of a semiconductor body with a laser beam through a first surface of the semiconductor body
Implementation Method 2
irradiating the semiconductor body with protons through the first surface
Implementation Method 3
annealing the semiconductor body in a temperature range of 300° C. to 550° C.
Data Source
AI summary
A method of manufacturing a semiconductor device includes forming a field stop zone by irradiating a portion of a semiconductor body with a laser beam through a first surface of the semiconductor body. The portion has an oxygen concentration in a range of 5×1016 cm−3 and 5×1017 cm−3. Then the semiconductor body is irradiated with protons through the first surface and annealed in a temperature range of 300° C. to 550° C.