Semiconductor Body Contact Zones via Platinum Diffusion
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Solution Overview
Problem
In field effect transistors, the reverse recovery charge contributed by the drift layer leads to dynamic switching losses, and existing methods using platinum impurities to reduce this charge result in degradation of charge carrier lifetime.
Innovation Solution
The method involves forming source and body contact zones of opposite conductivity types in a semiconductor die, with a metallic recombination element like platinum diffusing into the die to create silicide crystallites, resulting in body contact zones with a significantly higher dopant concentration, which reduces reverse recovery charge without degrading the transistor's on-state characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If platinum impurities are introduced into the semiconductor die to reduce reverse recovery charge, then the reverse recovery charge decreases, but the charge carrier lifetime is degraded
Solution Approach 1:
The patent applies local quality by creating body contact zones with significantly higher dopant concentration (at least 10 times higher than body zones) in specific regions between source zones. This localized high-doping approach reduces reverse recovery charge in the body contact zones without requiring widespread platinum impurity distribution throughout the entire drift layer, thereby maintaining charge carrier lifetime in the bulk semiconductor material while achieving the desired reduction in reverse recovery charge locally.
Solution Approach 2:
The patent changes the dopant concentration parameter by forming body contact zones with net dopant concentration at least ten times higher than the body zones. This parameter change allows the body contact zones to have enhanced charge carrier recombination capability, reducing reverse recovery charge, while the bulk semiconductor material maintains its original charge carrier lifetime characteristics.
2Loss of energy
If body contact zones with high dopant concentration are formed, then reverse recovery charge is reduced, but the manufacturing process complexity increases
Solution Approach 1:
The patent applies preliminary action by forming the body contact zones with high dopant concentration before final device assembly and testing. The diffused metallic recombination elements are introduced into the semiconductor die at an early stage, and the body contact zones are created between source zones during the fabrication process. This preliminary formation of body contact zones simplifies subsequent manufacturing steps while achieving the desired reduction in reverse recovery charge.
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 minimizes reverse recovery charge, enhancing the robustness of the semiconductor device by reducing charge carrier diffusion length and maintaining the on-state performance of the transistor.
Implementation Method 1
The impurity source is tempered so that atoms of a metallic recombination element diffuse out from the impurity source into the semiconductor die
Data Source
AI summary
In a semiconductor die, source zones of a first conductivity type and body zones of a second conductivity type are formed. Both the source and the body zones adjoin a first surface of the semiconductor die in first sections. An impurity source is provided in contact with the first sections of the first surface. The impurity source is tempered so that atoms of a metallic recombination element diffuse out from the impurity source into the semiconductor die. Then impurities of the second conductivity type are introduced into the semiconductor die to form body contact zones between two neighboring source zones, respectively. The atoms of the metallic recombination element reduce the reverse recovery charge in the semiconductor die. Providing the body contact zones after tempering the platinum source provides uniform and reliable body contacts.