IGBT Epitaxial Collector Doping Profile Control
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Solution Overview
Problem
Conventional insulated gate bipolar transistors (IGBTs) face challenges in accurately controlling the doping profiles of the back side portions, which affects their operating characteristics such as hole-injection and tail current characteristics, making it difficult to improve their performance.
Innovation Solution
The implementation of an epitaxial process to grow impurity-doped collector and buffer layers with non-normal doping profiles, allowing for precise control of doping concentrations in the depth direction, thereby improving the doping profiles and manufacturing of IGBTs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional doping methods are used to form the collector layer, then the manufacturing process is simple, but the doping profile cannot be precisely controlled
Solution Approach 1:
The patent changes the manufacturing method from conventional doping to epitaxial growth, fundamentally altering the process parameters to achieve precise doping profile control. By using epitaxial growth with controlled impurity incorporation during the growth process, the doping concentration and depth distribution can be precisely adjusted through growth rate, temperature, and gas flow parameters, resolving the contradiction between manufacturing precision and process complexity.
Solution Approach 2:
The patent replaces conventional mechanical/chemical doping methods with an epitaxial growth process. Instead of using ion implantation or diffusion techniques, the collector layer is formed through controlled crystal growth where impurities are incorporated during the epitaxial process, enabling superior doping profile control through process parameter optimization.
2Reliability
If the doping profile of the back side portion is not optimized, then the manufacturing process is straightforward, but the operating characteristics such as hole-injection and tail current are poor
Solution Approach 1:
The patent optimizes operating characteristics by changing the doping approach to epitaxial growth, where doping parameters can be precisely controlled during the growth process. This allows optimization of hole-injection and tail current characteristics through controlled impurity distribution in the collector layer, achieving superior device performance.
Solution Approach 2:
The patent performs preliminary doping action during the epitaxial growth process itself, rather than through subsequent separate doping steps. The impurity doping is incorporated into the collector layer formation process, allowing the doping profile to be established in advance with precise control over the final device characteristics.
3Manufacturing precision
If a normal doping profile is used in the collector layer, then the manufacturing is simpler, but the operating characteristics cannot be optimized
Solution Approach 1:
The patent achieves precise doping profile control by changing from normal doping to epitaxial growth methodology. Through controlled impurity incorporation during epitaxial growth, non-normal doping profiles with precise spatial distribution can be created, enabling optimization of device performance while maintaining manufacturing feasibility through process parameter control.
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 enables the manufacturing of IGBTs with enhanced operating characteristics, including improved hole-injection and tail current performance, by allowing for more accurate control of doping profiles, thus optimizing the transistor's performance.
Implementation Method 1
an epitaxial process to grow impurity-doped collector and buffer layers with non-normal doping profiles
Data Source
AI summary
A transistor includes a device portion and a collector layer. The device portion is in a first side of a semiconductor substrate, and includes a gate and an emitter. The collector layer is on a second side of the semiconductor substrate, which is opposite to the first side. The collector layer is an impurity-doped epitaxial layer and has a doping profile with a non-normal distribution.