IMAGING Infrared

Today, Time-of-Flight (ToF) systems are among the most innovative technologies offering imaging companies an opportunity to lead the market. Every major player wants to integrate these devices to provide functions such as 3D imaging, proximity sensing, ambient light sensing and gesture recognition. Sony/Softkinetic has been investigating this technology deeply, providing a unique pixel technology to several image sensor manufacturers in three application areas: consumer, automotive and industrial. For automotive applications, Sony/Softkinetic has licensed its technology to Melexis, which has worked on the pixel design to provide a ToF imager for gesture recognition.

The MLX75023 is an automotive 3D ToF Imager already integrated into gesture recognition systems from car makers like BMW. The 3D ToF Imager is packaged using Glass Ball Grid Array technology. The device comprises the die sensor and the glass filter in the same component in thin, 0.7 mm-thick, packaging.

This report analyzes the complete component, from the glass near-infrared band pass filter to the collector, based on the ToF pixel technology licenses developed by Softkinetic and improved by Melexis. The report includes a complete cost analysis and price estimation of the device based on a detailed description of the package, and the ToF imager.

It also features a complete ToF pixel technology comparison with Infineon, STMicroelectronics and Texas Instrument ToF imagers, which are also based on Sony/Softkinetic technology, with details on the companies’ choices.

Overview / Introduction

Melexis Company Profile and Time of Flight Technology

Physical Analysis

• Physical analysis methodology
• Package
  • View and dimensions
  • Package opening
  • Package cross-section: optical filter, RDL, bump
• Image Sensor Die
  • View, dimensions and marking
  • Die overview: active area, CPAD technology
  • Die delayering, main block ID and process
  • Cross-section: metal layers, pixel
  • Process characteristics

Physical Comparison with Infineon’s ToF Image Sensor, STMicroelectronics’ SPAD technology and Texas Instruments’ Industrial ToF Image Sensor

• Package, Pixels, Filters

Manufacturing Process Flow

• Overview
• CIS Front-End Process
• CIS Wafer Fabrication Unit
• Packaging Process Flow
• Final Assembly Unit

Cost Analysis

• Cost Analysis Overview
• The Main Steps Used in the Economic Analysis
• Yield Hypotheses
• CIS Die Cost
  • Front-end cost
  • Back-end: tests and dicing
  • Wafer and die cost
• Component
  • Packaging cost
  • Packaging cost by process step
  • Component cost

Estimated Price Analysis

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