Thin Bipolar Junction Manufacturing with Localized Heat Annealing
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Solution Overview
Problem
Manufacturing thinner bipolar junction devices with lower voltage ratings is challenging due to cracking during thermal processes, which affects the device's thickness and voltage blocking capability.
Innovation Solution
A method involving localized-heat annealing and reduced thickness for the lower side of the device, combined with lattice imperfections, to mitigate cracking and enhance manufacturing feasibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the substrate thickness is reduced to lower conduction loss and improve voltage blocking capability, then the device performance is improved, but the substrate becomes prone to cracking during thermal processes
Solution Approach 1:
The patent applies preliminary action by creating lattice imperfections through ion implantation (He+) and radiation exposure before the thermal diffusion process. These pre-induced imperfections act as stress relief points that prevent cracking during subsequent thermal processing, enabling the use of thinner substrates without compromising structural integrity
Solution Approach 2:
The patent changes the physical state and structural parameters of the substrate by introducing lattice imperfections through ion implantation and radiation. This modifies the substrate's mechanical properties to reduce cracking susceptibility, allowing thickness reduction from conventional >150 microns to 40-150 microns while maintaining reliability
2Manufacturing precision
If the substrate thickness is reduced to achieve lower voltage rating devices, then the voltage blocking capability is improved, but the manufacturing process becomes more difficult due to cracking
Solution Approach 1:
The patent performs preliminary lattice imperfection creation through ion implantation and radiation exposure before thermal diffusion. This preliminary action prepares the substrate structure to resist cracking during manufacturing, making the production of thin substrates (40-150 microns) feasible and reliable
Solution Approach 2:
The patent introduces lattice imperfections as an intermediary factor that mediates between the conflicting requirements of thin substrate thickness and cracking resistance. These imperfections act as stress relief mechanisms that enable manufacturing success
3Reliability
If conventional thermal annealing is used to activate doping regions, then the doping activation is effective, but cracking occurs in thinner substrates
Solution Approach 1:
The patent applies local quality by using localized heat annealing techniques (laser annealing, plasma annealing, infrared lamp annealing) that concentrate heat in specific regions rather than heating the entire substrate uniformly. This localized approach activates doping regions effectively while minimizing overall thermal stress and cracking in the thin substrate
Solution Approach 2:
The patent substitutes conventional thermal annealing with localized heat annealing methods (laser, plasma, infrared). This replacement maintains doping activation effectiveness while reducing the harmful thermal stress that causes cracking in thin substrates
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
Enables the production of bipolar junction devices with reduced thickness and improved voltage ratings without cracking, maintaining voltage blocking capability and reducing conduction loss.
Implementation Method 1
thermally diffusing the upper P-type region and the upper N-type region
Implementation Method 2
localized-heat annealing the lower P-type region and the lower N-type region
Implementation Method 3
Creating the lattice imperfections comprises at least one selected from a group comprising: ion implantation; ion implantation of He+
Implementation Method 4
exposure of the substrate to radiation by electrons
Data Source
AI summary
Bipolar junction devices, and methods for manufacturing the same. At least one example of making a bipolar junction device includes doping an upper side of a substrate with an upper P-type region and an upper N-type region, thermally diffusing the upper P-type region and the upper N-type region, the substrate having a thickness of greater than 150 microns during the thermally diffusing, reducing the thickness of the substrate to between and including 40 and 150 microns, doping a lower side of the substrate with a lower P-type region and a lower N-type region, and then localized-heat annealing the lower P-type region and the lower N-type region.