Image Sensor Leakage Current Reduction via Intermediary Semiconductor Layer
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Solution Overview
Problem
Existing image sensors face issues with leakage current due to the formation of N/P junctions and defects caused by the etching process, leading to pixel noise and reduced device performance.
Innovation Solution
The image sensor design includes a semiconductor substrate with doped regions and a contact formed on the semiconductor layer without direct contact with active regions, using a shallow junction formed by annealing dopants to reduce leakage current and minimize damage during the manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a contact is directly formed on the active region through conventional etching, then the manufacturing process is simple, but leakage current increases and device performance deteriorates
Solution Approach 1:
A semiconductor layer is introduced as an intermediary between the contact and the active region. This intermediate layer prevents direct contact between the contact and the active region, thereby eliminating the harmful leakage current while still allowing electrical connection to be established through the semiconductor layer.
Solution Approach 2:
The semiconductor layer is formed and doped with dopants before the contact is created. Through preliminary annealing treatment, the dopants are activated and diffused into the semiconductor layer in advance, ensuring that the semiconductor layer has the appropriate electrical properties before the contact is formed, thus preventing leakage current from the outset.
2Manufacturing precision
If conventional etching is used to form contacts, then the manufacturing process is straightforward, but defects are introduced in the junction field
Solution Approach 1:
The semiconductor layer serves as a protective intermediary that shields the underlying junction field from the harmful effects of the etching process. The etching is performed on the semiconductor layer rather than directly on the active region, preventing defect formation in the junction field while still allowing contact formation.
3Reliability
If dopants are annealed to form a shallow junction, then leakage current is reduced, but additional manufacturing steps are required
Solution Approach 1:
The dopants are introduced and annealed in advance during the semiconductor layer formation process, before the contact is created. This preliminary doping and annealing treatment activates the dopants and creates the desired electrical properties in the semiconductor layer, ensuring that the shallow junction is formed before the contact fabrication begins.
Solution Approach 2:
The doping process and the semiconductor layer formation process are merged into a single integrated process step. The dopants are introduced during the semiconductor layer deposition or immediately afterward, and the annealing is performed as part of the same processing sequence, reducing the total number of separate manufacturing steps.
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 reduces leakage current and improves device performance by minimizing direct damage to active regions and avoiding defects in the junction field, resulting in enhanced image quality.
Implementation Method 1
the second doped region is formed by dopants in the semiconductor layer that are annealed to be diffused to a surface layer of the first doped region
Data Source
AI summary
The present disclosure relates to the technical field of semiconductors, and discloses an image sensor and a manufacturing method therefor. The image sensor includes: a semiconductor substrate; a first active region located on the semiconductor substrate; a doped semiconductor layer located on the first active region; and a contact located on the semiconductor layer, where the first active region includes: a first doped region and a second doped region abutting against the first doped region, wherein the second doped region is located at an upper surface of the first active region, and wherein the second doped region is formed by dopants in the semiconductor layer that are annealed to be diffused to a surface layer of the first doped region. The present disclosure may reduce leakage current and improve device performances.