Fig. 2: Basic procedure for the production of a SiCer system
Fig. 1: Basic concept of the sicer idea: Integration of many sensoric functional elements on a platform consisting of silicon and multilayer ceramics (LTCC) with electrical, fluidic and optical interfaces

Growth core HIPS (High Performance Sensors)

The goal of the HIPS (High Performance Sensors) growth core is the development and joint marketing of new types of robust, highly integrated sensors based on a unique combination of silicon technology and ceramic multilayer technology (SiCer). The silicon is permanently bonded to the ceramic carrier at wafer level. By combining the advantages of both technology worlds, a new, unique technology platform is created for a large number of different sensors with a wide range of applications.

12 regional companies, 7 research institutions and 5 associated partners from the Thuringian technology triangle Jena/Hermsdorf-Erfurt-Ilmenau are working together in the HIPS alliance. In this alliance, the partners are for the first time in a position to offer comprehensive solutions for high-performance sensors that are not yet available worldwide in SiCer form. The aim is to develop innovative materials, processes and components on this new technology platform that can be used in a variety of ways and thus create the prerequisites for the broad development of new fields of application for sensor technology (Fig. 1).

 

Basic procedure for the production of a SiCer system (Fig. 2):

After pre-processing of both substrate layers (silicon and LTCC green films), they are aligned and stacked. The subsequent lamination and sintering (900 °C) results in a quasi-monolithic composite substrate (SiCer). This can then be further processed using MEMS technologies. Subsequent processing with packaging and interconnection technologies uses the capability/property of LTCC as a ceramic circuit carrier to integrate parts of the sensor electronics (primary electronics) directly on the transducer (short, vertical conduction paths). At the same time a housing can be realized if required.

This provides a material composite in which a variety of materials as well as micro- and nanostructures can be monolithically integrated into the LTCC or on the silicon side of the substrate. The thermal adaptation of the system thus allows both the use of high-temperature processes in production and the use of the finished system under high-temperature conditions of at least 600 °C. This results in the following advantages for SiCer sensors:

- High functional integration (multi-sensor properties) by linking silicon and LTCC technology - robustness through carrier function of the LTCC ceramic and high bonding strength between LTCC and silicon: up to 5000 N/cm² - Inertness due to gas-tight bonding interface (He-tightness <1.1-10-8 mbar-l/s) - Compatibility with thin-film and MEMS processes (standard equipment) - Cost-effective due to wafer-level packaging - Miniaturization due to 3D sensor design - Integration of fluid channels - Temperature stability due to inorganic materials and robust electrical and thermal vias (up to at least 600 °C) - Simple thermal management due to the extreme difference in thermal conductivity of the composite substrate Silicon: 150 W/(m-K), LTCC: 5 W/(m-K)

Within the framework of the research work at the TU Ilmenau, three closely linked joint projects are being worked on:

VP1: Development of SiCer basic technologies for applications in high performance sensor technology - SiCer basic technologies

The subproject includes the research, further development and evaluation of the SiCer platform with the aim of opening up new materials and functional elements for high-performance sensor applications and raising the processes required for this to a level with which the implementation strategy of the industrial joint project partners can be fulfilled. Within the consortium, TU Ilmenau has the greatest wealth of experience in the SiCer composite technology and will drive forward the technology transfer to the partners.

VP2: Development and construction of SiCer-based, multifunctional sensor systems for the application area "liquid sensor technology

The aim of this subproject is the transfer and demonstratorical application of SiCer technology in the design and construction of liquid sensors. The different materials, manufacturing technologies, structural and functional elements of the SiCer platform are to be investigated and applied for different topic areas (TS) regarding their properties, application potentials and scalability for "high-performance liquid sensors". In this subproject there are three main topics that are being worked on and each of them represents different application examples for multifunctional SiCer sensor systems in the field of liquid sensor technology:

- SiCer-Multi-λ-Sensor for water monitoring - SiCer-Humidity-Sensor for aggressive environments - SiCer-Impedance-Sensor for flow cytometry and biofilm monitoring

VP3: SiCer-based transducers for gas sensor applications

The sub-project includes the development, technological implementation and evaluation of SiCer-based sensor elements for gas sensor technology. In concrete terms, three prototypical applications for a structure in the composite substrate technology SiCer are to be implemented first separately from each other and then combined in a sensor demonstrator. The challenge of the joint project is based on the strongly differing specifics of the individual prototypical applications infrared sensor, pressure sensor and temperature sensor. In the technological implementation of the sensor element, different processes and process sequences have to be applied in each case, which could possibly influence each other or in extreme cases exclude each other (e.g. high-temperature processes that allow piezoelectric strain sensors to drift away by diffusion).

Subproject leader: Univ.-Prof. Dr.-Ing. Jens Müller
Research assistants: Dipl.-Ing. Michael Fischer, M. Sc. Cathleen Kleinholz, M. Sc. Sebastian Gropp
Project duration: 09/2019 - 12/2022
Project management agency: Forschungszentrum Jülich GmbH
Funding: BMBF - Federal Ministry of Education and Research

partner:
Institute for Bioprocess and Analytical Measurement Technology (IBA) Heiligenstadt, CiS Forschungsinstitut für Mikrosensorik GmbH (CiS) Erfurt, IFU GmbH (Lichtenau), Ernst-Abbe-Hochschule Jena (EAH) Jena, Friedrich-Schiller-University Jena (FSU), Fraunhofer Institute for Ceramic Technology und Systeme (IKTS) Hermsdorf, LUST Hybrid-Technik GmbH (LHT) Hermsdorf, Micro-Hybrid Electronic GmbH (MHE) Hermsdorf, Micro-Sensor GmbH (MSE) Hermsdorf, Siegert Thinfilm Technology GmbH (STFT) Hermsdorf, VIA electronic GmbH (VIA) Hermsdorf, 5microns GmbH (5M) Ilmenau, Ilmsens GmbH (ILSN) Ilmenau, IL Metronic Sensortechnik GmbH (ILM) Ilmenau, Institute for Microelectronic and Mechatronic Systems gGmbH (IMMS) Ilmenau, Kompass GmbH (KOM) Ilmenau, UST Umwelt Sensor Technik GmbH (UST) Geschwenda, LLT Applikation GmbH (LLT) Ilmenau

Associated partners:
Osyso GmbH (Osyso) Jena, CMOS-IR GmbH (CIR) Erfurt, Landesentwicklungsgesellschaft Thüringen mbH (LEG) Erfurt, JenaBatteries GmbH Jena, X-FAB MEMS Foundry GmbH Erfurt

3DWeMo

The project 3DWeMo (2D and 3D material morphologies for reactive microjoining in electronics) investigates the influence of substrate morphology on a reactive multilayer layer. Even progressive reactions of metallic multilayers, especially those based on Ni/Al, have been extensively investigated over the last decades. The focus has been on nanofilms and sputtered layer systems. The exploitation of these reactions for the joining of electronic chips or micromechanical components (MEMS) offers the advantage of a locally limited heat load. The chain reaction triggered by local ignition is difficult to control and the reaction products often exhibit high stresses. It is known that nanoscale radii of curvature influence the surface and interfacial energy. This is to be exploited to specifically influence the free enthalpy of a multilayer sequence and thus influence acceleration and speed of the reaction propagation. An additional factor is the changed multilayer morphology due to the nanostructure, which also influences the progress of the reaction. In the project different multilayer architectures are investigated, taking into account both the surface shape and the layer structure. Their influence on the phase transformation is investigated.

Thus, the basis for the development of prefabricated structures for a future chip assembly is laid. The acquired knowledge contributes to tailor-made packaging and interconnection technology, which in future will exploit defined ignition paths for the dosed energy input in solder connections for chip assembly.

Project Manager: Dr.-Ing. Heike Bartsch

Research assistant: M. Sc. Konrad Jaekel

Project duration: 15.11.2019 - 14.11.2022

Funding: DFG

Partner: Department of Materials in Electrical Engineering

Silicon-ceramic hybrid substrate as integration platform for photoacoustic and optical applications (PaSiC)

The aim of the project is the further development of the silicon-ceramic sintered composite technology into an industrially widely applicable technology platform for the realization of robust and miniaturized IR components (IR radiation sources and detectors) as well as novel cost-efficient sensors based on photoacoustic and optical principles. For this purpose, the Technology Readiness Level (TRL) of the composite technology achieved from upstream projects is to be raised from 4 to 5-6 in stages.

The research project addresses the combination of the inorganic non-metallic LTCC ceramic with the semi-metallic silicon for a gas-tight composite without permanent organic additives. The joint sintering of silicon and glass ceramic is a central unique selling point. Both materials can be bonded together by sintering on a laboratory scale largely free of pressure and stress. No polishing of the two material partners is necessary for this, but the pre-processed green tape stack of the ceramic is laminated onto a pre-processed silicon wafer and then sintered. The resulting SiCer-hybrid substrate can be further processed - with adapted thin-film processes. The silicon is thus available for MEMS processes, while the LTCC ceramic can be used as a carrier for other functions (e.g. fluidics), as a rewiring level and as a package. Thus, the hybrid substrate offers ideal conditions for the realization of optical sensor elements directly in the silicon wafer. On the other hand, the use of LTCC ceramics as wiring level also allows the classical hybrid integration of further sensor and electronic components.

Contact: Prof. Dr.-Ing. Jens Müller, Dipl.-Ing. Nam Gutzeit

Project duration: 07/2020 - 12/2022

Founding: BMBF

Project partners: Infineon Technologie AG Neubiberg, Micro-Hybrid Electronic GmbH Hermsdorf, CMOS-IR Erfurt, Fraunhofer IKTS Hermsdorf, Fraunhofer IPM Freiburg im Breisgau

Memristive materials for neuromorphic electronics (MemWerk)

LTCC wafers with vertical contacts (vias) and a surface suitable for lithography

The aim of the MemWerk (Memristive Materials for Neuromorphic Electronics) project is to develop new functional memristic materials for energy-efficient neuromorphic electronics, i.e. electronic systems whose principle is based on paradigms of biological information processing.

Memristive materials have a memory effect and can change their electronic properties (electrical resistance) by external signals (e.g. electrical current or voltage, gases, light, temperature, etc.). Consequently, these materials enable the creation of devices whose functions are in many respects similar to those of synapses in neural networks. They thus form the central plastic building block in artificial neural networks (ANNs).

The development focus of the subproject is on system integration. Connection and contact concepts are developed and tested that electrically address a larger field or cluster of memristive components without recourse to intersection structures.

The following concepts will be considered in the implementation of this task:

a) Construction of flip-chip memristive matrices on a multilayer LTCC substrate.

b) Direct integration of memristors on a suitable pre-assembled substrate with already implemented wiring. This approach uses low-temperature single-fired ceramic substrates (LTCC) with adapted expansion coefficients. The technology enabled the wiring of up to 100 layers. The smoothing of the sintered LTCC surface is a main focus of development. Polishing processes on different surfaces are used for smoothing.

Subproject manager: Jens Müller

Funding: Carl-Zeiss-Stiftung

Term: 04/2020 - 03/2025

Contact: Dr.-Ing. Heike Bartsch, Dr. Kateryna Soloviova

Link: https://memwerk.de/

Reactive micro-joining and packaging - mechanical, thermal and electrical functionalities

Figure 1: The project addresses the application of the predetermination of process routes by predefined morphologies and microstructures to manufacture interconnections with desired properties as well as functionalities in the area of microelectronic packaging

The research project focuses on the application of reactive multilayers in the area of microelectronic interconnection technologies. The proposed work aims to investigate the capabilities to build up reactive multilayers on pre-designed layer structures and morphology, which are able to offer predetermined joining processes at the microscale level in electronics packaging (Fig. 1). In contrast to the published solutions in the field of IC bonding, the project will not only focus on the bonding process itself, but also on the joint’s electrical, thermal and mechanical functionality and reliability. This approach enables a fundamental evaluation and verification of the central research hypothesis with regard to the versatility of reactive micro joining in microelectronics packaging. Moreover, the research targets also the application of the concept for hidden area array interconnects (e.g. Flip-Chip components).

The project tries to make use of a reactive material system with a pre-designed surface morphology and layer structure, which imitates the “idealized” morphologies and microstructures, fabricated using nanotechnologies (e.g. magnetron sputtered 3D-structured layers). The application adapted morphology-layer-combination is optimized to predetermine the joining process in terms of temperature profile and solidification front route, and thus to produce a desired functionality of the joint through its structure-properties-relations, without any posterior structuring processes. The resulting functionalities will be determined by electrical, thermal and mechanical characterization of the joint. Investigations on the joints’ microstructure shall show the cause-and-effect-relation between the predefined morphology and the resulting properties. In this regard, the project combines not only the different ways of synthesizing tailored morphologies under the constrains of scaling for application, but collaborates also with the simulation project partners, to provide objectives for fundamental, or design and manufacturing.

Subproject leader: Prof. Dr.-Ing. Jens Müller

Contact person: Dipl.-Ing. Alexander Schulz

Project duration: 09/2019 - 12/2022

Founding: German Research Foundation (DFG)

Partner: Saarland University, Department of Systems Engineering, Chair of Microintegration and Reliability

Research group E-PhoQuant

The Thuringian Innovation Center InQuoSens intends to strategically strengthen its position in the research and innovation field of quantum technologies with the research group E-PhoQuant. The application of quantum physical phenomena will revolutionize information transmission and processing with regard to data security. Within the scope of the research, a heterogeneous integration solution for the realization of compact quantum optical components and modules is to be developed. Based on a novel composite substrate, a system-in-package platform will be created to realize highly integrated combined microelectronic/optical systems. This system approach is not only aimed at miniaturization, but also builds on wafer-level structuring technologies, which is a prerequisite for a future transfer to industry. To this end, the following focal points are to be addressed in particular:

  • Technological realization of optical surface quality and high-precision electrical contacting structures on composite substrates,
  • Surface and volume functionalization of the optical layer by means of plasma- and UKP-laser-based processing
  • Design and integration of quantum optical functional structures in composite substrates
  • System integration of electronic components

To solve the tasks an interdisciplinary approach is pursued in the research group, which is also reflected in the composition.

Project leader: Prof. Dr.-Ing. Jens Müller

Research assistent: Dipl.-NanoSc. Mahsa Kaltwasser

Project duration: 01/2021 - 12/2022

Partners: TU Ilmenau, Department of Technical Optics (Prof. Stefan Sinzinger); FSU Jena, Institute of Physics, FG Ultrafast Optics (Prof. Stefan Nolte) and FG Microstructrue Technologies (Prof. Uwe Zeitner)

VEDIAS - digital, internationally oriented study programmes with social virtual reality application (VEDIAS-VR)

In VEDIAS, two engineering programs leading to a Master of Science (MSc) degree and a social science-oriented program leading to a Master of Arts (MA) degree are being prototypically developed and tested with respect to digital studyability. All three study programs have been internationally successful as face-to-face formats for several years. In addition to the general testing of online studyability, specific aspects are addressed in each of the three study programs. For the Micro- and Nanotechnologies (MNT) MSc program, which is the main focus of work in the Electronics Technology group, the focus is on creating and testing an adequate digital substitute for access to complex laboratory facilities that previously required on-site study. The electronics technology team is strengthened by the digital teaching experts of all participating groups of the MNT program.

Project leader: Univ.-Prof. Dr.-Ing. Jens Müller

Research associate:   M. Sc. Christina Helm

Project term: 01/2021 - 12/2022

Founding: DAAD