Sony’s 2-Layer Transistor Pixel in the IMX888 CIS

Overview / Introduction  

• Executive Summary
• Reverse Costing Methodology
• Exmor T 2-Layer Transistor Pixel Technology
• Glossary

Company Profile  

Physical Analysis     

• Summary of the Physical Analysis
• Sony Xperia 1 V Teardown
• IMX888 CMOS Image Sensor
  • Overview
  • Die Corners
  • Delayering
  • Cross Section
  • Process Summary

Physical Comparison with Exmor RS 

Manufacturing Process Flow  

• Fabrication Units
• Front-End Processes
• Back-End Processes

Cost Analysis  

• Main Steps of the Economic Analysis
• Yields Explanation and Hypotheses
• Manufacturing Costs
  • Front-End Costs
  • Back-End Costs
  • Die Costs

Cost Comparison with Exmor RS     

Selling Price    

Feedback     

Related Products     

About Yole Group

Sony, TSMC

Key Features

• Detailed photos
• Precise measurements
• Materials analysis
• Manufacturing process flow
• Supply chain evaluation
• Manufacturing cost analysis
• Selling Price Analysis
• Comparison with Exmor RS

Product objectives

This is a full reverse costing and technology report on the IMX888 Exmor T CIS with 2-layer transistor pixel.  It includes complete technical and physical analysis of the CIS with images from optical and scanning electron microscopy (SEM) and chemical analysis by energy-dispersive X-ray (EDX) spectroscopy.  We then use this information combined with supply chain analysis to determine the manufacturing steps and calculate the cost breakdown.  Finally, we estimate the final selling price of the CIS.  Physical and cost comparison is made between the Exmor  T and Exmor RS technologies.

Sony’s Exmor T is the first 2-layer transistor pixel to market

The CMOS Image Sensor (CIS) market seeks smaller pixels, lower noise and higher dynamic range.  Unfortunately, these goals are contradictory, largely because achieving high pixel pitch means scaling down the pixel transistors, which adversely affects the signal-to-noise ratio, and limiting the photodiode size and supply voltage, reducing light collection efficiency.  In conventional pixel structures, designers play with parameters such as transistor size, photodiode shape and circuit layout to strike the appropriate balance between these contradictory objectives.  It’s not surprising then, that the main design houses have dedicated significant energy to developing innovative solutions to break free of this frustrating dilemma.

One such solution is the 2-layer transistor pixel. By distributing the transistors of the pixel circuit between two stacked active layers, they can be made larger.  While this has already been accomplished for larger pixels by using in-pixel hybrid bonding, this results in long contact distances and makes it challenging to then connect a logic circuit.  In the 2-layer transistor pixel, the two transistor layers are less than a micron apart and they share the same back-end of line, effectively forming a monolithic pixel circuit wafer.

Sony is far and away the CIS market leader, representing over 40% of the $22B market (2022). With the recent release of the IMX888 Exmor T CIS with 2-layer transistor pixel, they are the first to market with this type of technology. In addition to achieving an impressive 2-layer transistor pixel structure, Sony has also introduced a full-trench electrical isolation scheme with an oxide fill, which mitigates photon absorption by the trenches.  This allows for larger photodiodes, increasing photon collection and dynamic range.

This is a full reverse costing and technology report on the IMX888 Exmor T CIS with 2-layer transistor pixel.  It includes complete technical and physical analysis of the CIS with images from optical and scanning electron microscopy (SEM) and chemical analysis by energy-dispersive X-ray (EDX) spectroscopy.  We then use this information combined with supply chain analysis to determine the manufacturing steps and calculate the cost breakdown.  Finally, we estimate the final selling price of the CIS.  Physical and cost comparison is made between the Exmor  T and Exmor RS technologies.