TVS Diode N+ Buried Layer Uniformity via Segmented Implantation
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Solution Overview
Problem
The existing manufacturing processes for transient voltage suppressor (TVS) diodes result in poor uniformity of the N+ type buried layer, leading to high junction capacitance, which affects the current withstand ability and signal attenuation, making it difficult to effectively protect circuits.
Innovation Solution
A diode structure and manufacturing method involving a two-step dopant implanting and drive-in process to form N+ type semiconductor layers with a discontinuous dopant concentration distribution, ensuring better uniformity and low junction capacitance, thereby improving the stability and performance of the ultra-low capacitance TVS device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single-step dopant implanting and drive-in process is used to form the N+ type buried layer, then the manufacturing process is simple, but the dopant distribution uniformity is poor leading to high junction capacitance
Solution Approach 1:
The single-step dopant implanting and drive-in process is divided into two separate steps: first implanting and driving in to form an initial N+ type layer, then second implanting and driving in to form the final N+ type buried layer with optimized dopant distribution. This segmentation allows each step to be independently optimized, achieving both manufacturing feasibility and precise dopant distribution control with reduced junction capacitance.
2Manufacturing precision
If the dopant concentration is increased to reduce junction capacitance, then the capacitance decreases, but the dopant distribution uniformity deteriorates
Solution Approach 1:
The dopant implantation is segmented into two steps with different dopant concentrations and implantation conditions. The first step uses higher concentration to establish the buried layer foundation, while the second step uses optimized concentration to achieve precise dopant distribution uniformity and target junction capacitance values, preventing the uniformity deterioration that occurs with single-step high-concentration implantation.
Solution Approach 2:
The first implanting and drive-in step performs a preliminary action to create the N+ type buried layer structure and establish the basic dopant distribution. This preliminary layer then serves as the foundation for the second implanting step, which refines the dopant distribution to achieve uniformity and target capacitance values, rather than attempting to achieve both in a single step.
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 method achieves improved dopant distribution uniformity, stabilizing the diode's operating efficiency and ensuring the TVS device can reliably protect circuits by maintaining capacitance within a specified range, effectively addressing the issue of high junction capacitance.
Implementation Method 1
Both of the first semiconductor layer and the second semiconductor layer are extended toward the interior of the semiconductor substrate from the first surface of the semiconductor substrate by implanting a dopant
Implementation Method 2
removing the photoresist and diffusing the first semiconductor layer in the semiconductor substrate
Data Source
AI summary
A diode structure and a manufacturing method are disclosed. The diode structure includes a semiconductor substrate, a first semiconductor layer, a second semiconductor layer and an epitaxy layer. The semiconductor substrate includes a first surface. The first semiconductor layer and the second semiconductor layer are extended toward the interior of the semiconductor substrate from the first surface by implanting a dopant. Both of the semiconductor types of the first semiconductor layer and the second semiconductor layer are opposite to the semiconductor type of the semiconductor substrate. The epitaxy layer is formed on the first surface, connected with the first semiconductor layer and the second semiconductor layer and extended outwardly from the first surface. The first semiconductor layer and the second semiconductor layer are connected with each other, continuously. The concentration distribution of the dopant within the first semiconductor layer and the second semiconductor layer is in a discontinuous curve.