Ahead of its competitors, Apple has begun using 3D sensing. For the iPhone’s 10th anniversary, Apple integrated this new function under the name “True Depth sensing”. The system features a near-infrared (NIR) camera, a dot projector, and a flood illuminator, along with a proximity sensor. All modules work together to form a high-end security solution: facial recognition.
Since the Apple 7, STMicroelectronics has supplied Apple with a custom proximity sensor, one which represents the smallest FlightSenseTM device in its ToF portfolio. And with the Apple X, STMicroelectronics has gained significant market share by integrating several of its components (from the NIR camera to the 3D touch controller), including a new custom version of the proximity sensor featuring a flood illuminator.
Located in the front above the main speaker, the proximity sensor/flood illuminator is packaged using optical LGA. The device is unique to Apple. In the past, STMicroelectronics released a custom proximity sensor two times smaller (2.80 x 2.40 mm) than the devices in its portfolio, based on FlightSenseTM technology. This new version comes with a flood illuminator used in the True Depth system. The flood illuminator is an NIR VCSEL with a wide beam that illuminates the face and allows for nighttime user recognition with the NIR camera. The packaging is specially designed for the flood illuminator’s heat management.
In this report the complete microsystem is analyzed, from the two illumination devices (which are vertical-cavity surface-emitting lasers (VCSEL)) to the collector (based on the SPAD developed by STMicroelectronics). Moreover, a complete cost analysis and price estimate is presented for the device, based on a detailed description of the package, the ToF detector, the VCSEL, and the second VCSEL for flood illumination.
Also featured is a complete technology comparison with STMicroelectronics’ ToF portfolio since its first generation: the VL53L0X, the VL6180X, and the most recent custom proximity sensor in the Apple iPhone 8.
1. Overview / Introduction
2. STMicroelectronics – Company Profile & Time of Flight (ToF) Technology
3. Apple iPhone X Plus – Teardown
4. Physical Analysis
Physical Analysis Methodology
View and dimensions
Package opening and wire bonding process
Package cross-section: adhesives, PCB, filters, FOV, diffuser, ceramic
View and dimensions
Wire bonding, cavity
View, dimensions and marking
Die overview – active area, SPADs technology
Die delayering, main blocks’ ID and process
Cross-section – metal layers, SPADs
5. Physical Comparison with Apple’s iPhone 8, the VL53L0X, and the VL6180X
Package, Functions, FOV, Optical Blocking Package, ASIC & VCSEL, SPADs
6. Manufacturing Process Flow
ASIC and VCSELs Front-End Process
ASIC and VCSELs Wafer Fabrication Unit
Packaging Process Flow
7. Cost Analysis
Cost Analysis Synthesis
Economic Analysis – Main Steps Used
ASIC & VCSEL Die Cost
Back-end – tests and dicing
Wafer and die cost
Packaging cost per process steps