Skip to main content

Highly Integrated Optoelectronic Sensor

Periodic Reporting for period 3 - HIOS (Highly Integrated Optoelectronic Sensor)

Reporting period: 2018-08-01 to 2019-07-31

From personal mobile devices, to wearables, smart homes, offices, cars, and more, people are using more and more sensors. Sensor functionality is evolving rapidly, from making our phones more intuitive and lighting solutions more intelligent to conserving battery power and enabling breakthrough medical technologies. Sensors therefore play a key role in many applications in fields such as mobile and consumer, automotive, or industrial. One thing is constant across the fields: the challenging demand for high performance (high sensitivity, low power consumption) often in combination with small size and low cost. This drives the need for sensor integration with electronics and other system components. For a sensor solutions provider like ams AG and process and equipment suppliers like APC, Boschman and Bühler this means that they have to be at the forefront of sensor integration to be competitive in their respective markets, a goal that can only be achieved by close collaboration.
HIOS – “Highly Integrated Optoelectronic Sensor” addresses this need for collaborative innovation for the growing market for intelligent light sensors. In particular HIOS aims to develop and launch the world’s first light sensor with fully integrated optical stack including multiple filters, lenses and an aperture replacing multiple discrete components. The 3D sensor, IC filter and Wafer Level Optics integration technology developed in the HIOS project enables to bring cost-efficient, very small, and high-performance sensor to the market but can also be applied to multiple other sensor applications.
For this reason a high-volume production environment for 3D / Through Silicon Via (TSV) has been set up by ams AG which is now extended by equipment and processes for on-chip inorganic optical filters and wafer level molding to form on-chip optical components.

Market opportunity lies in growth markets that have a high demand for low size and/or low cost, but cannot compromise on quality, and are therefore a perfect fit to the HIOS products. The three main markets are:
• Wearable Market
• Low Cost Consumer Market (smart phones, cellular)
• Smart Lighting Market
1. Wafer Level Molding with best-in-class alignment accuracy and process control
2. Tailored Filter design with tightest pass bandwidth control; low stress filter deposition to enable multiple filters
3. Light sensors of smallest size and lowest system cost at best optical performance simplifying assembly and enabling a new class of very thin consumer products
The ambitious goal of HIOS was to develop a worldwide leading class of new optical sensor products, with highest integration of components and miniaturization. Initially, an Ambient Light Sensor was planned – for a color sensor, only preparation for later launch seemed reachable. To reach the common goal, all partners had to push the boundaries of what is possible in their field, as well as have a seamless cooperation. Bühler made new equipment developments and enhancements developed for advanced optical interference filter processing and announced in February 2019 their new deposition tool for High Performance Optical Coating HELIOS Gen II. It is the latest version of the highly successful sputter tool, with improved layer distribution and enhanced low particle process. New hardware and process allow for meeting increasing tight specifications with high productivity and yield.
Boschman successfully established a new level of accuracy with their molding tool and process development for optical packaging application being capable to form diffusor layers, lenses and apertures.
As planned all these developments were successfully demonstrated for implementation on ams family of ambient light sensors products. Based on the excellent quality of the interference filters developed in this project new spectral color sensor products have been designed covering applications for UV, visible and infrared.
In 2018 already a first color sensing product was launched delivering the first engineering samples for a miniaturized 3x6 channel spectral sensor family (AS7265x).
Due to growing interest for this new highly integrated color sensing applications ams AG successfully launched in January 2019 the color sensor AS7341, an 11-channel spectrometer for spectral identification and color matching applications. This sensor enables with 8 channels covering the whole visible range from UV to near infrard spectral sensing functions for mobile devices. With additional 3 extra channels for Clear, NIR and Flicker it allows exact determination of 50Hz or 60Hz ambient light flicker to minimize distortion of ambient light sources.
The overall maturity of the proposed solution is given by the maturity of the sensor platform on which the new products are based, the molding system, and the filter system.

Sensor product: As the market leader in advanced light sensors, ams delivers very high volumes of ambient light and proximity sensors for a broad range of consumer devices. The proposed solution is based on the existing ams Ambient Light Sensor product family, a very-high sensitivity light-to-digital converter that transforms light intensity into a digital signal output. The device combines a broadband photodiode (visible plus infrared), an IR photodiode, and a photopic IR-blocking filter on a single CMOS circuit. Two integrating ADCs convert the photodiode currents into a digital output that represents the irradiance measured on each channel.
All technologies listed above for the existing product TSL2584TSV have Technology Readiness Level 9.
The new color sensing function based on interference filters have been successfully demonstrated and brought to TRL9 maturity during the course of this project. This enabled the accelerated launch of new spectral color sensing products from ams AG delivering highest accuracy and smallest form factor.

Filter deposition system: The high-end system (Bühler Helios 800) was the starting point for further improvements. The film thickness control with high accuracy, high deposition rate (>0.5nm/s) and a uniformity of +/- 0.5% achieved on 200mm wafers made the Helios sputtering system ideally suited for high end production of optical interference filters.

The following developments were targeted for the specific application of HIOS going beyond production requirements at the project start:
- capable to achieve challenging filter specification in combination with direct optical monitoring
- Semiconductor environment compatible,
- load lock cassette handling system reaching low defect levels.

In the scope of the project, the readiness for the specific application has been successfully increased to TRL9, delivering in this project with HELIOS Gen II the next improved filter deposition tool generation demonstrating
- capability to achieve tight filter specifications for UV bandpass filter and combined dielectric metal filter
- optimized accuracy of process technology to achieve high yield (>99.8%) on wafers coated with up to six different filters
- improved uniformity on 200 mm wafer by new magnetic uniformity tuning device

Selective mold system: Boschman has further improved its wafer mold systems that are routinely used.
With enhancements of the alignment system and the handling system new alignment accuracy for wafer level molding processes have been achieved and successfully demonstrated.