Periodic Reporting for period 3 - Caladan (Micro assembled Terabit/s capable optical transceivers for Datacom applications)
Reporting period: 2022-01-01 to 2023-12-31
Caladan is focused upon the development of densely integrated optical transceivers for the data centers that underpin today’s internet. The Covid crisis has underlined how critical the internet is to our society, and has led to large increases in the bandwidth and capacities that need to be handled by today’s data center infrastructure. The recent emergence of AI applications is driving an enormous demand for computational resources, doubling every 3 to 4 months (!). In turn this is creating a strong demand for Terabit capable optical transceivers.
The backbone of these AI and cloud-based applications are data centers which consist of servers arranged into racks and interconnected using a hierarchical network. As the capacity and density of servers continues to grow, the links between them need to handle increasing capacity as well. In the past reporting period, we’ve witnessed emergence of the first 800G and even 1.6T optical transceivers. Interestingly, it is expected that the optical pluggables which were earlier predicted to be taken over by co-packaged optics, will last longer than originally thought, with 3.2T modules already being considered. This has to do with the difficulties in terms of supply chains and challenging specifications for co-packaged optics. Today, despite the use of complex Photonic Integrated Circuits (PICs) which allow integrating a large number of optical components such as modulators, photodetectors, possibly lasers and multiplexing functions into a chip, the fabrication of an optical transceiver still requires a large amount of sequential fabrication steps. Indeed photonics, high-speed electronics, fiber attachment parts such as fiber blocks need to be assembled piece-by-piece, even involving operator assisted active alignment. Testing also needs to be done piece-by-piece, which is costly at high volumes. It is important to note that even with a move to 300mm wafer manufacturing lines for Silicon Photonics, the increased amount of chips that can be extracted from a single 300mm wafer will require a linear increase in the amount of flip-chip, wirebonding, fiber attachment and other assembly equipment to maintain throughput.
The main objective of CALADAN is to break these bottlenecks. CALADAN will demonstrate automated, wafer-level integration of photonics and electronics into Terabit/s capable optical engines using micro transfer printing on 300mm Silicon Photonic engines, and connect these optical engines with fiber arrays using an industrially scalable vision-based automatic fiber attachment process. In this way, CALADAN will remove throughput bottlenecks in assembly lines and will be able to manufacture optical transceivers at 50% less cost compared to conventional solutions, achieving <0.1€/Gb/s for throughputs above 1million transceivers per year. The objectives are:
1) Demonstration of an automated wafer-level heterogeneous micro assembly process to integrate SiGe BiCMOS 56Gbaud integrated circuits onto Silicon Photonic transceivers manufactured in a 300mm wafer fabrication line.
2) Demonstration of an automated wafer-level heterogeneous micro assembly process to integrate uncooled quantum dot GaAs O-band lasers onto Silicon Photonic transceivers realized in a 300mm wafer fabrication line, capable of delivering +13dBm up to 85C
3) Demonstration of an automated vision based fast fiber attachment process using “through substrate” Silicon Photonic grating couplers with total assembly time less than 120 seconds per optical engine.
4) Demonstration of Terabit/s (multichannel 56Gbaud PAM-4 and 56Gbaud 16-ADPSK) optical transceivers using the micro transfer printing enabled manufacturing and fast fiber attachment processes.
5) Definition of wafer-level test procedures and testability for the manufacturing flow.
6) Establishment of a supply chain for Datacom Terabit/s transceivers manufactured using the CALADAN approach at 50% less cost compared to existing solutions for inter-rack and intra-rack applications, reaching 0.1€/Gb/s for volumes of at least 1million units per annum.
The backbone of these AI and cloud-based applications are data centers which consist of servers arranged into racks and interconnected using a hierarchical network. As the capacity and density of servers continues to grow, the links between them need to handle increasing capacity as well. In the past reporting period, we’ve witnessed emergence of the first 800G and even 1.6T optical transceivers. Interestingly, it is expected that the optical pluggables which were earlier predicted to be taken over by co-packaged optics, will last longer than originally thought, with 3.2T modules already being considered. This has to do with the difficulties in terms of supply chains and challenging specifications for co-packaged optics. Today, despite the use of complex Photonic Integrated Circuits (PICs) which allow integrating a large number of optical components such as modulators, photodetectors, possibly lasers and multiplexing functions into a chip, the fabrication of an optical transceiver still requires a large amount of sequential fabrication steps. Indeed photonics, high-speed electronics, fiber attachment parts such as fiber blocks need to be assembled piece-by-piece, even involving operator assisted active alignment. Testing also needs to be done piece-by-piece, which is costly at high volumes. It is important to note that even with a move to 300mm wafer manufacturing lines for Silicon Photonics, the increased amount of chips that can be extracted from a single 300mm wafer will require a linear increase in the amount of flip-chip, wirebonding, fiber attachment and other assembly equipment to maintain throughput.
The main objective of CALADAN is to break these bottlenecks. CALADAN will demonstrate automated, wafer-level integration of photonics and electronics into Terabit/s capable optical engines using micro transfer printing on 300mm Silicon Photonic engines, and connect these optical engines with fiber arrays using an industrially scalable vision-based automatic fiber attachment process. In this way, CALADAN will remove throughput bottlenecks in assembly lines and will be able to manufacture optical transceivers at 50% less cost compared to conventional solutions, achieving <0.1€/Gb/s for throughputs above 1million transceivers per year. The objectives are:
1) Demonstration of an automated wafer-level heterogeneous micro assembly process to integrate SiGe BiCMOS 56Gbaud integrated circuits onto Silicon Photonic transceivers manufactured in a 300mm wafer fabrication line.
2) Demonstration of an automated wafer-level heterogeneous micro assembly process to integrate uncooled quantum dot GaAs O-band lasers onto Silicon Photonic transceivers realized in a 300mm wafer fabrication line, capable of delivering +13dBm up to 85C
3) Demonstration of an automated vision based fast fiber attachment process using “through substrate” Silicon Photonic grating couplers with total assembly time less than 120 seconds per optical engine.
4) Demonstration of Terabit/s (multichannel 56Gbaud PAM-4 and 56Gbaud 16-ADPSK) optical transceivers using the micro transfer printing enabled manufacturing and fast fiber attachment processes.
5) Definition of wafer-level test procedures and testability for the manufacturing flow.
6) Establishment of a supply chain for Datacom Terabit/s transceivers manufactured using the CALADAN approach at 50% less cost compared to existing solutions for inter-rack and intra-rack applications, reaching 0.1€/Gb/s for volumes of at least 1million units per annum.
1) Realization and demonstration of a heterogeneous integration process that allows to integrate 130nm SiGe BiCMOS electronic integrated circuits (EICs) onto 300mm Silicon Photonic wafers. Two generations of SiGe BiCMOS EICs have been designed and fabricated. Using the fabricated chips, a micro transfer-printing process was developed that allowed transfer-printing SiGe BiCMOS chiplets onto dedicated sites on a full 300mm Silicon Photonic wafer. This technology allows for massively parallel and dense integration of electronics with photonics. The chiplet designs have been confirmed to operate till 64Gb/s, significant progress was made towards realization of a process for low-ohmic connections between the chiplets and the target wafer.
2) Realization and demonstration of heterogeneous integration processes that allow for integration of two types (evanescent-coupled and edge-coupled) of GaAs quantum dot lasers onto 300mm Silicon Photonic wafer sites.
3) Both processes above relied on application of ultra-thin (order of magnitude 100nm) adhesive layers which were spray coated on the target wafers.
4) Both a short-loop and full-loop 300mm Silicon Photonic run were designed and fabricated under the scope of the project, the latter containing numerous transceiver test structures, and recesses supporting the integration of both above mentioned laser types.
5) Establishing and demonstrating an automated and vision-based fiber assembly system, which through a combination of passive and active alignment steps allows to line up a fiber array within well less than 10 seconds.
6) Progress was made towards establishing supply chains to support micro-transfer printing enabled optical transceivers. In particular at imec a low-volume micro-transfer printing pilot line is established, constructed around a 200mm wafer-scale transfer printing tool.
2) Realization and demonstration of heterogeneous integration processes that allow for integration of two types (evanescent-coupled and edge-coupled) of GaAs quantum dot lasers onto 300mm Silicon Photonic wafer sites.
3) Both processes above relied on application of ultra-thin (order of magnitude 100nm) adhesive layers which were spray coated on the target wafers.
4) Both a short-loop and full-loop 300mm Silicon Photonic run were designed and fabricated under the scope of the project, the latter containing numerous transceiver test structures, and recesses supporting the integration of both above mentioned laser types.
5) Establishing and demonstrating an automated and vision-based fiber assembly system, which through a combination of passive and active alignment steps allows to line up a fiber array within well less than 10 seconds.
6) Progress was made towards establishing supply chains to support micro-transfer printing enabled optical transceivers. In particular at imec a low-volume micro-transfer printing pilot line is established, constructed around a 200mm wafer-scale transfer printing tool.
Progress beyond state-of the art:
1) First demonstration of micro transfer printable GaAs quantum dot lasers based on edge-coupled and evanescent-coupled structures, whereby more than 20mW optical power was coupled into the Silicon waveguides,
2) First demonstration of transfer-printing of SiGe BiCMOS chiplets and GaAs quantum dot laser coupons onto a complete 300mm Silicon Photonic wafer.
3) Demonstration of a fast vision-based fiber alignment system, facilitating the alignment process in under 10 seconds.
Potential impact: 1) under the scope of the PhotonixFAB project, imec is currently establishing its Silicon Photonic technology at X-FAB to support high-volume production. This transfer will include the necessary process modules (fabrication of recesses in the back-end of the process) to allow micro-transfer printing. 2) imec has established a low-volume pilot line that can operate on 200mm wafers to allow both internal development of micro transfer-printing technology, as well as development by third parties. 3) under the scope of follow-up project such as Horizon Europe PUNCH (GaAs QD coupons), HiConnects (300mm Silicon Photonics based transceivers, development steered by NVidia), PhotonixFAB (200mm based Silicon Photonics transceivers whose development is led by application partners Nvidia and Nokia) the micro transfer-printing technology on imec’s Silicon Photonics technology is being further developed.
1) First demonstration of micro transfer printable GaAs quantum dot lasers based on edge-coupled and evanescent-coupled structures, whereby more than 20mW optical power was coupled into the Silicon waveguides,
2) First demonstration of transfer-printing of SiGe BiCMOS chiplets and GaAs quantum dot laser coupons onto a complete 300mm Silicon Photonic wafer.
3) Demonstration of a fast vision-based fiber alignment system, facilitating the alignment process in under 10 seconds.
Potential impact: 1) under the scope of the PhotonixFAB project, imec is currently establishing its Silicon Photonic technology at X-FAB to support high-volume production. This transfer will include the necessary process modules (fabrication of recesses in the back-end of the process) to allow micro-transfer printing. 2) imec has established a low-volume pilot line that can operate on 200mm wafers to allow both internal development of micro transfer-printing technology, as well as development by third parties. 3) under the scope of follow-up project such as Horizon Europe PUNCH (GaAs QD coupons), HiConnects (300mm Silicon Photonics based transceivers, development steered by NVidia), PhotonixFAB (200mm based Silicon Photonics transceivers whose development is led by application partners Nvidia and Nokia) the micro transfer-printing technology on imec’s Silicon Photonics technology is being further developed.