Back Side Illumination Sensor Grid Planarity via Damascene Process
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Solution Overview
Problem
Current methods for manufacturing back side illumination (BSI) image sensors lack improved planarity and uniformity of the back side surfaces, leading to inefficiencies in light reflection and image signal capture.
Innovation Solution
A metal grid is formed on the back side of a semiconductor workpiece using a damascene process, involving the deposition and patterning of insulating and conductive materials, followed by chemical-mechanical polishing to achieve a uniform grid structure that enhances the planarity and uniformity of subsequent material layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional manufacturing methods are used for BSI image sensors, then the manufacturing process is simple, but the planarity and uniformity of the back side surface are poor
Solution Approach 1:
The back side surface is segmented into multiple regions by forming a grid structure with insulating material layers and conductive material fills. This segmentation allows different regions to have different properties, improving overall planarity and uniformity while managing the complexity through systematic patterning
Solution Approach 2:
The insulating material layer is formed and patterned before the conductive material is filled into the grid structures. This preliminary action ensures that the grid framework is established to guide subsequent material deposition, achieving better planarity control in the final surface
2Productivity
If the back side surface is not properly planarized, then the manufacturing process is simpler, but light reflection increases reducing image signal capture
Solution Approach 1:
The grid structure provides local quality variations with conductive material fills in specific regions surrounded by insulating material. This local differentiation allows precise control of light interaction at different locations, reducing unwanted reflection while maintaining signal capture efficiency
Solution Approach 2:
The grid structure with conductive material fills converts potentially harmful light reflection into beneficial light absorption and signal generation. The conductive regions act as light traps that convert reflected light into useful image signals, turning a harmful effect into a benefit
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 improves the uniformity of insulating material layers and reduces light reflection, resulting in enhanced image signal capture and performance of BSI sensors by ensuring uniform light absorption and improved manufacturing processes.
Implementation Method 1
chemical-mechanical polishing to achieve a uniform grid structure that enhances the planarity and uniformity of subsequent material layers
Implementation Method 2
ensuring uniform light absorption and improved manufacturing processes
Implementation Method 3
reduces light reflection, resulting in enhanced image signal capture and performance
Data Source
AI summary
Semiconductor devices and back side illumination (BSI) sensor manufacturing methods are disclosed. In one embodiment, a method of manufacturing a semiconductor device includes providing a workpiece and forming an integrated circuit on a front side of the workpiece. A grid of a conductive material is formed on a back side of the workpiece using a damascene process.