Image Sensor Structure Masking for Overlay-Shift-Free Doping
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Solution Overview
Problem
The manufacturing process of image sensors requires multiple photomasks, leading to increased costs and the issue of overlay shift, which complicates the formation of isolation and doped regions.
Innovation Solution
A method that uses a single photomask to form both the isolation and doped regions by performing ion implantation processes with a patterned hard mask layer and subsequent hard mask layers, allowing for flexible adjustment of region widths through recess thickness adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple photomasks are used in the manufacturing process, then the isolation region and doped region can be formed separately, but the manufacturing cost increases and overlay shift errors occur
Solution Approach 1:
The patent merges the formation of the isolation region and doped region into a single photomask step. The hard mask layer is patterned with a single photomask to define both regions simultaneously, eliminating the need for multiple separate photomask steps and their associated alignment errors.
Solution Approach 2:
The single patterned hard mask layer serves multiple functions: it defines the isolation region boundaries, defines the doped region boundaries, and acts as a mask for both ion implantation processes. This multi-functionality reduces the total number of photomasks required.
2Manufacturing precision
If multiple photomasks are used to form isolation region and doped region, then each region can be precisely controlled, but the manufacturing cost increases
Solution Approach 1:
The patent combines multiple region formation steps into a single photomask step. The hard mask layer is patterned once to define both the isolation region and doped region, reducing manufacturing cost while maintaining precise dimensional control through the conformal deposition process.
Solution Approach 2:
The patent uses conformal deposition to create the hard mask layer, which automatically maintains uniform thickness and precise dimensional relationships between features. By controlling deposition parameters, the method achieves precise region dimension control without requiring multiple photomasks.
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 the number of photomasks needed, minimizes overlay shift issues, and enables the production of smaller image sensor devices by determining and adjusting the doped region width based on recess dimensions.
Implementation Method 1
A first ion implantation process is performed on the substrate structure by using the first patterned hard mask layer as a mask to form a first isolation region in the substrate structure
Implementation Method 2
A second ion implantation process is performed on the substrate structure by using the first hard mask layer as a mask to form a doped region in the substrate structure
Data Source
AI summary
A manufacturing method of an image sensor structure including the following steps is provided. A substrate structure is provided. A first patterned hard mask layer is formed on the substrate structure. The first patterned hard mask layer has a first opening. A first ion implantation process is performed on the substrate structure by using the first patterned hard mask layer as a mask to form a first isolation region in the substrate structure. A first hard mask layer is formed on the first patterned hard mask layer. The first hard mask layer is formed in the first opening to form a first recess. The width of the first recess is smaller than the width of the first opening. A second ion implantation process is performed on the substrate structure by using the first hard mask layer as a mask to form a doped region in the substrate structure.