What is dToF technology?
Recently, Apple Inc. applied dToF technology for the first time in its newly released iPad Pro device, bringing unprecedented ecological opportunities for 3D imaging technology.
ToF technology can be divided into two types: Direct ToF (dToF) and Indirect ToF (iToF). Among them, dToF sends discrete laser pulses, which can achieve ultra-low duty cycle. Compared to iToF, it is more energy-efficient and has faster imaging speed. However, it has high technical barriers and hardware requirements. Due to the advantages of dToF in fast information acquisition, anti-interference, and imaging clarity compared to iToF, with the continuous maturity and improvement of algorithm technology and hardware equipment, dToF is expected to become the mainstream solution for deep sensing imaging technology.
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The main difference in principle between dToF and iToF lies in the difference between emitted and reflected light. The principle of dToF is relatively straightforward, which is to directly emit a light pulse, and then measure the time interval between the reflected light pulse and the emitted light pulse to obtain the flight time of the light. The principle of iToF is more complex. In iToF, the emitted light is not a single light pulse, but modulated light. There is a phase difference between the received reflected modulated light and the emitted modulated light, and by detecting this phase difference, the flight time can be measured, thereby estimating the distance.The application of ToF technology not only helps to enhance personal entertainment experience, but also may be seen in all aspects of future work and life. In the near future, ToF technology will quickly penetrate into personal mobile terminals, and it will further become a high-quality technological solution for application scenarios such as smart payments and smart homes. In industries, healthcare, automotive, and other fields, the 3D dynamic experience brought by ToF technology makes remote operations more convenient, promoting the intelligence, automation, and real-time application of related fields.
How can Changguang Yuanchen provide a backlit solution for dToF technology?
Compared to iToF, dToF has much better performance, but its production process is also more complex. Changguang Yuanchens globally advanced backlit CMOS image sensor production line can provide research and development, as well as processing and production services for dToF technology.
Changguang Yuanchen utilizes existing image sensor backlighting technology and 3D hybrid bonding to improve the sensitivity, temporal resolution, and dynamic range of ToF devices, and solves the serious trade-off between filling imprints and pixel functions. Compared to other imaging technologies, SPAD has three key comprehensive advantages: single photon sensitivity, picosecond time resolution, and devices integrated into standard CMOS technology. At nanosecond and picosecond time resolutions, detailed three-dimensional (3D) images can be formed by measuring the time of flight (ToF) of light pulses. High frame rate imaging of single photons can generate new functions in super-resolution microscopy. In addition, imaging of quantum effects such as photon entanglement can also be achieved.
The main process flow of backlit dToF is as follows:
1. Hybrid Bonding
Cu Cu hybrid bonding achieves high-density pixel connections, and this process can reduce pixel unit size due to the independent detector and circuit components. Changguang Yuanchen can customize Cu Cu hybrid bonding technology research and manufacturing according to customer design requirements.
As shown in the figure, the upper layer of the wafer is a SPAD (including counting and timing), and the lower layer of the wafer is a readout circuit lCu Cu interconnect interface2. Silicon Thinning
By optimizing the three-step process of mechanical grinding, chemical corrosion, and CMP, precise thinning of wafers can effectively remove the internal damage layer of silicon wafers and reduce wafer stress.
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3. DTI
As the pixel size decreases, it can lead to issues such as FWC and suppression of crosstalk. FWC can be solved by increasing the silicon thickness, and using DTI structure can solve the crosstalk problem. DTI building isolation walls will increase light utilization to reduce interference, as shown in the figure:4. ARC layer sedimentation
By using enhanced plasma vapor deposition equipment, single or mixed deposition coatings can be obtained, and the density and purity of the film layer can be accurately controlled.
5. Pad Open
Changguang Yuanchen can draw and customize lithography plates for customers, ensuring alignment accuracy and no impurities or residues in the Pad area.
Changguang Yuanchen will provide comprehensive backlit technical support to our customers, helping them fully utilize our technical capabilities and best meet their needs.
? About Changguang Yuanchen
Changchun Changguang Yuanchen Microelectronics Technology Co., Ltd. (hereinafter referred to as Changguang Yuanchen) was established on December 29, 2016, with a registered capital of 360 million yuan. Changguang Yuanchen is an independent semiconductor manufacturing enterprise specializing in the processing of backlight CMOS image sensor wafers. We are committed to providing BSI SOI and special chip level processing services for 200mm and 300mm wafer manufacturing, as well as research and production services for Color Filter&Microlens. At the same time, we can provide customized services according to customer project requirements, such as BSI-CIS, Stack BSI, SOI, MEMS, fiber optic waveguides, 3D ToF, optical thin films (ARC), etc.
The companys main goal is to develop and manufacture backlight CMOS image sensor chips for mid to high end applications, providing solutions to meet the manufacturing needs of customers for mid to high end CMOS image sensors. In the future, it will build an integrated semiconductor enterprise that integrates design, manufacturing, and packaging testing, providing highly competitive high-quality products and services to global customers.