Thomas Kämpfe

Thomas Kämpfe
Fraunhofer Institute for Photonic Microsystems IPMS | IPMS · Center Nanoelectronic Technologies (IPMS-CNT)

Dr. rer. nat.

About

173
Publications
32,910
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
1,220
Citations
Additional affiliations
September 2019 - present
Fraunhofer Institute for Photonic Microsystems IPMS
Position
  • Group Leader
Description
  • CMOS Integrated RF & AI
January 2017 - August 2019
Fraunhofer Institute for Photonic Microsystems IPMS
Position
  • PostDoc Position
March 2016 - May 2016
Stanford University
Position
  • Visiting Graduate Researcher
Education
September 2011 - March 2012
University of Colorado Boulder
Field of study
  • Physics
October 2006 - May 2011
Technische Universität Dresden
Field of study
  • Physics

Publications

Publications (173)
Article
Full-text available
The pyroelectric response of polycrystalline, Si-doped HfO2 layers in a thickness range of 10 nm to 50 nm is investigated employing the temperature oscillation method. The largest value of the pyroelectric coefficient is obtained for the 20 nm layer with p = 84 μC m−2 K⁻¹, which is similar to that of lithium niobate. Furthermore, the pyroelectric c...
Article
Full-text available
The recent discovery of ferroelectricity in thin film HfO2 materials renewed the interest in ferroelectric FET (FeFET) as an emerging nonvolatile memory providing a potential high speed and low power Flash alternative. Here, we report more insight into FeFET performance by integrating two types of ferroelectric (FE) materials and varying their prop...
Conference Paper
Full-text available
We report 1-3 bit/cell FeFET operation through optimized HSO and HZO ferroelectric laminate layers using alumina interlayers. Memory window up to 3.5V, switching speed of 300ns, 10 years retention, and 10^4 endurance are reported. The gate stack lamination merits are discussed with insight potential of FeFET as an MLC memory.
Conference Paper
Full-text available
This paper presents an efficient crossbar design and implementation intended for analog compute-in-memory (ACiM) acceleration of artificial neural networks based on ferroelectric FET (FeFET) technology. The novel mixed signal blocks presented in this work reduce the device-to-device variation and are optimized for low area, low power and high throu...
Article
Full-text available
In spite of the increasing use of machine learning techniques, in-memory computing and hardware have increased the interest to accelerate neural network operation. Henceforth, novel embedded nonvolatile memories (eNVMs) for highly scaled technology nodes, like ferroelectric field effect transistors (FeFETs), are heavily studied and very promising....
Conference Paper
This paper reports a semi-empirical, SPICE compatible and computationally efficient compact model of ferroelectric capactitors (Fe-CAP). This compact model is inspired by the Jiles-Atherton model of ferroemagnts, which has much smaller computation time than other state-of-the-art models. This model successfully reproduces the evolution of memory wi...
Article
Full-text available
Devices based on ferroelectric hafnium oxide are of major interest for sensor and memory applications. In particular, Si-doped hafnium oxide layers are investigated for the application in the front-end-of-line due to their resilience to high thermal treatments. Due to its very confined doping concentration range, Si:HfO2 layers based on thermal ato...
Article
Full-text available
This paper reports 2bits/cell ferroelectric FET (FeFET) devices with 500 ns write pulse of maximum amplitude 4.5V for inference-engine applications. FeFET devices were fabricated using GlobalFoundries 28nm high-k-metal-gate (HKMG) process flow on a 300mm wafer. The devices were characterized, and statistical modeling of variations in the fabricated...
Article
Full-text available
Ferroelectric hafnium oxide is of major interest for a multitude of applications in microelectronics, ranging from neuromorphic devices to actuators and sensors. While the electrical performance is commonly discussed in depth, the influence of the microstructure is often disregarded. However, in recent years more and more research groups shed light...
Presentation
The presence of ferroelectricity in hafnium oxide thin films can be controlled via doping. Since those layers are usually deposited via atomic layer deposition, the doping element (like Zr, Al, Si, La) is supplied via monolayers. This way, the metastable ferroelectric phase can be stabilized. However, often wake-up effects and asymmetries like impr...
Article
This work reports 2bits/cell hafnium oxide-based stacked resistive random access memory devices fabricated on flexible polyimide substrates for neuromorphic applications considering the high thermal budget. The ratio of low resistance state current (ION) to high resistance state current (IOFF) or ION/IOFF for the fabricated devices was above 1.4 ×...
Conference Paper
In our work we describe and demonstrate an alternative approach of integrating 1T-1C FeFET having separated transistor (1T) without modifying frontend CMOS technology and an additional gate-coupled ferroelectric (FE) capacitor (1C) embedded in the interconnect layers. Starting from the results of FE capacitor integration and 1T-1C single cell chara...
Preprint
Full-text available
p>Interfacial Layer Engineering to Enhance Endurance and Noise Immunity of FeFETs for IMC Applications</p
Chapter
Recently, deep neural networks (DNNs) have proved their success in performing various tasks at high accuracy. However, these networks come at a high cost of computational and memory requirements and with the continuously growing neural networks sizes, conventional von Neumann accelerators hit the memory wall. Processing-in-memory (PIM) acceleration...
Conference Paper
This paper presents a performance study of the 22nm FDSOI transistor through the design and simulation of a wideband two-stage power amplifier (PA). The PA design flow includes preliminary characterization and modeling of the core active device. The matching networks are designed through 3D electromagnetic (EM) simulation by using Ansys HFSS. The p...
Conference Paper
Study on the effect of nanosecond laser anneal (NLA) induced crystallization of ferroelectric (FE) Si-doped hafnium oxide (HSO) material is reported. The laser energy density (0.3 J/cm2 to 1.3 J/cm2) and pulse count (1.0 to 30) variations are explored as pathways for the HSO based metal-ferroelectric-metal (MFM) capacitors. The increase in energy d...
Conference Paper
Recently, hafnium oxide based ferroelectric memories gained great attention due to good scalability, high speed operation, and low power consumption. In contrast to the FRAM concept, the FeFET offers non-destructive read-out. However, the integration of the FeFET into an established CMOS technology entails several challenges. Herein, an 1T1C FeFET...
Conference Paper
HfO2-based ferroelectric FETs (FeFETs) offer excellent retention, scalability, and memory window. However, achieving high endurance is still challenging. Here, a fluorination treatment is presented that enables significant endurance and device stability improvement. Noise and charge pumping methods are applied to obtain deeper understanding of the...
Conference Paper
We report ferroelectric (FE) laminate HSO/HZO MFMIS FeFETs. An MFM/MIS area ratio control enables low voltage operation and 10 5 endurance. FE lamination (2 × 10 nm, 4 × 5 nm) and low FE anneal reduce the FeFET variability. Impact of the stack (MFMIS), material type/lamination, and FE anneal are studied for enhanced FeFET reliability and reduced va...
Article
Today, a large number of applications depend on deep neural networks (DNN) to process data and perform complicated tasks at restricted power and latency specifications. Therefore, processing-in-memory (PIM) platforms are actively explored as a promising approach to improve the throughput and the energy efficiency of DNN computing systems. Several P...
Preprint
div>This paper reports high precision, highly linear MAC operation conducted on 28nm ferroelectric (Fe) FET (FeFET) based 4Kb computing-in-memory (CIM) core with 1FeFET-1T structure. The CIM-macro consists of 4 Kbit ultra-high precision FeFET based synaptic core, ADCs, and peripheral components for data processing. The crossbar array in the synapti...
Conference Paper
The following study employs RF waveform engineering to monitor degradation in 22nm FDSOI transistor at high-frequency region. The current and voltage waveforms are measured, reconstructed, and de-embedded to the device’s intrinsic during large-signal CW RF stress testing. This technique provides extra information on device performance compared with...
Conference Paper
Strained-SiGe channel structures have been widely exploited in advanced nanoscale CMOS technology nodes to enhance the performance of p-FETs, especially in the high frequency domain. By relaxing the contacted poly pitch (CPP) to gain beneficial strain effect, a previous study has reported a significant improvement in the transconductance, and thus,...
Conference Paper
The development process of the FDSOI CMOS technology is continuously ongoing to improve the performance for high-frequency applications, especially for power amplification. Meanwhile, customized transistor devices pose difficulties to be integrated fast into the existing foundry’s PDK for nonlinear analysis. This paper thereby presents an empirical...
Conference Paper
This paper presents a highly linear 79 GHz differential low-noise amplifier (LNA) for civil-automotive radars operating at the predefined frequency range from 77 GHz to 81 GHz. The circuit is optimized for frequency-modulated continuous-wave (FMCW) radar application, which typically require a very high input-referred 1 dB-compression point (iP1dB)....
Poster
Full-text available
With increasing complexity of image classification tasks, the required memory, latency and energy costs of doing edge computing becomes the bottle neck at many applications. This is due to the high cost of doing great numbers of multiply-accumulate (MAC) operations. The best solution for this issue is to adopt a more hardware aware training approac...
Article
Perpendicular magnetic tunnel junctions (p-MTJs) arise great interest due to their excellent performance in spin-transfer-torque magnetic random access memories (STT-MRAMs). Here the resistance states can be manipulated by an applying current in the order of 10 ⁹ ∼ 10 ¹⁰ A/m ² , yet the appearance of a heating influence must be understood. In this...
Preprint
Full-text available
Content addressable memory (CAM) is widely used in associative search tasks for its highly parallel pattern matching capability. To accommodate the increasingly complex and data-intensive pattern matching tasks, it is critical to keep improving the CAM density to enhance the performance and area efficiency. In this work, we demonstrate: i) a novel...
Conference Paper
Hafnium oxide-based ferroelectric tunnel junctions (FTJs) are novel nonvolatile memory devices with promising advantages such as non-destructive readout in comparison to conventional ferroelectric random access memories (FRAMs). Reliability aspects of FTJ devices need to be investigated, including their endurance, retention, ferroelectric switching...
Conference Paper
More and more applications use deep neural networks (DNN) to execute complex tasks. Depending on the application, there are high requirements regarding latency and performance parameters, especially for edge devices (edge AI). Due to the increasing challenges regarding Moore's Law, new approaches are required. A promising candidate for this is anal...
Conference Paper
In recent years various emerging memory concepts are in discussion for versatile application as low power solution in edge devices or as high performance memory in novel computing architectures. Among others, ferroelectric memories based on CMOS compliant hafnium oxide are promising candidates for fulfilling the application requirements. In our pap...
Article
Full-text available
The properties of hybrid ferroelectric (FE) and antiFE (AFE) films integrated in a single capacitor stack is reported. The stack lamination (4 × 5 nm) or (2 × 10 nm) using an Alumina (Al2O3) interlayer, material type (Si-doped HfO2 (HSO) and Zr doped HfO2 (HZO)), precursor condition (TEMA-Hf and Hf/ZrCl4), or dopant concentration (Si and Zr) are in...
Chapter
Due to the slow-down of Moore’s Law and Dennard Scaling, new disruptive computer architectures are mandatory. One such new approach is Neuromorphic Computing, which is inspired by the functionality of the human brain. In this position paper, we present the projected SEC-Learn ecosystem, which combines neuromorphic embedded architectures with Federa...
Article
Full-text available
This work presents 2 bits/cell operation in deeply scaled ferroelectric finFETs (Fe-finFET) with 1µs write pulse of maximum ±5V amplitude and WRITE endurance above 109 cycles. Fe-finFET devices with single and multiple fins have been fabricated on SOI wafer using a gate first process, with gate lengths down to 70 nm and fin width 20 nm. Extrapolate...
Article
Nearest neighbor (NN) search computations are at the core of many applications such as few-shot learning, classification, and hyperdimensional computing. As such, efficient hardware support for NN search is highly desired. In-memory computing using emerging devices offers attractive solutions for NN search. Solutions based on ternary content-addres...
Article
Nonvolatile memories especially the ferroelectric (FE)-based ones such as ferroelectric tunnel junctions (FTJs) and ferroelectric field-effect transistors (FeFETs) have recently attracted a lot of attention. FTJs have been intensively researched for the last decade and found to be very promising memory devices due to their significant nondestructiv...
Article
Full-text available
Ferroelectricity in crystalline hafnium oxide thin films is strongly investigated for the application in non-volatile memories, sensors and other applications. Especially for back-end-of-line (BEoL) integration the decrease of crystallization temperature is of major importance. However, an alternative method for inducing ferroelectricity in amorpho...
Article
Full-text available
Non-volatile memories based on ferroelectric hafnium oxide, especially the ferroelectric field-effect transistor (FeFET), have outstanding properties, e.g. for the application in neuromorphic circuits. However, material development has focused so far mainly on metal–ferroelectric–metal (MFM) capacitors, while FeFETs are based on metal–ferroelectric...
Preprint
Full-text available
Deep random forest (DRF), which incorporates the core features of deep learning and random forest (RF), exhibits comparable classification accuracy, interpretability, and low memory and computational overhead when compared with deep neural networks (DNNs) in various information processing tasks for edge intelligence. However, the development of eff...
Conference Paper
This paper investigates reconfigurable physical unclonable function (PUF) design by exploiting the polarization switching variation and stochasticity in ferroelectric field-effect-transistors (FeFETs). The proposed PUFs include 1-transistor/cell (1T/C) and 2T/C designs. The denser 1T/C PUF splits random ‘0’ and ‘1’ states using a tactically pre-def...
Conference Paper
This paper investigates reconfigurable physical unclonable function (PUF) design by exploiting the polarization switching variation and stochasticity in ferroelectric field-effect-transistors (FeFETs). The proposed PUFs include 1-transistor/cell (1T/C) and 2T/C designs. The denser 1T/C PUF splits random ‘0’ and ‘1’ states using a tactically pre-def...
Article
In this article, we present the capacitance-voltage (C-V) characteristics of HfₓZr₁₋ₓO₂metal-ferroelectric-metal (MFM) thin-film capacitors with various Zr doping, thicknesses, and annealing temperatures. The influence of doping, electric field cycling, and annealing temperature on tuning characteristics (tunability) was analyzed and an optimized b...
Article
Full-text available
A microwave characterization at UHF band of a ferroelectric hafnium zirconium oxide metal-ferroelectric-metal (MFM) capacitors for varactor applications has been performed. By using an impedance reflectivity method, a complex dielectric permittivity was obtained at frequencies up to 500 MHz. Ferroelectric Hf0.5Zr0.5O2 of 10 nm thickness has demonst...
Conference Paper
Hafnium oxide based ferroelectric FETs (FeFETs) are highly suitable for in-memory computing applications like neuromorphic hardware due to their CMOS compatibility, high dynamic range, low power consumption and good linearity. Device-to-device and die-to-die variability play an important role, especially due to the polycrystalline nature of ferroel...
Article
Full-text available
Reliability is a central aspect of hafnium oxide-based ferroelectric field effect transistors (FeFETs), which are promising candidates for embedded non-volatile memories. Besides the device performance, understanding the evolution of the ferroelectric behaviour of hafnium oxide over its lifetime in FeFETs is of major importance for further improvem...
Article
Full-text available
A multi-level cell (MLC) operation as a 1–3 bit/cell of the FeFET emerging memory is reported by utilizing optimized Si doped hafnium oxide (HSO) and hafnium zirconium oxide (HZO) based on ferroelectric laminates. An alumina interlayer was used to achieve the thickness independent of the HSO and HZO-based stack with optimal ferroelectric properties...
Article
Full-text available
In this article, we investigate the capacitance–voltage (C–V) characteristics of $$\text {Hf}_{x}\text {Zr}_{1-x}\text {O}_{2}$$ Hf x Zr 1 - x O 2 metal-ferroelectric-metal (MFM) thin-film capacitors with various Zr doping for varactor applications. The impact of field cycling during the wake-up process on the capacitance was analyzed. In addition,...
Article
Full-text available
The discovery of ferroelectricity in the fluorite structure based hafnium oxide (HfO2) material sparked major efforts for reviving the ferroelectric field effect transistor (FeFET) memory concept. A Novel metal-ferroelectric-metal-ferroelectric-insulator-semiconductor (MFMFIS) FeFET memory is reported based on dual ferroelectric integration as an M...
Conference Paper
Advanced non-volatile memory concepts such as the 1T1C ferroelectric (FE) random-access memory (FeRAM) and the 1T1C FE field-effect transistor (FeFET) can be realized by connecting a metal-ferroelectric-metal (MFM) capacitor placed in the back end of line (BEoL) of a microchip to the drain and gate contacts of a standard logic device, respectively....
Article
Full-text available
The hafnium oxide material class is characterized by the coexistence of several polymorphs between which phase transitions are induced by means of composition and external electric fields. Pyroelectric materials, which convert heat into electrical energy, exhibit the largest response at such morphotropic or field-induced phase transitions. The hafn...
Cover Page
Full-text available
With the help of transmission Kikuchi diffraction the major physical mechanism of antiferroelectric-like behavior as well as of the wake-up effect is determined by Maximilian Lederer, Konrad Seidel, and co-workers in article number 2100086. Furthermore, guidelines on how to influence this behavior by crystallographic texture and adjacent layers, as...
Conference Paper
The back-end-of-line (BEoL) integration of ferroelectric hafnium zirconium oxide (HZO) has many advantages for applications like non-volatile memories and sensors. Using transmission Kikuchi diffraction (TKD), the influence of process parameters like annealing conditions and Zr content on the microstructure are investigated here. TKD analysis allow...
Conference Paper
Recently, ferroelectric field-effect transistors (Fe-FETs) based on hafnium oxide (HfO 2 ) have been shown to be promising candidates for synaptic devices in neuromorphic applications. The polycrystalline structure of the ferroelectric layer strongly impacts the memory storage as well as the synaptic device performance, especially for highly scaled...
Conference Paper
In this work, the tuning properties of hafnium zirconium oxide (HZO) metal-ferroelectric-metal (MFM) thin film varactors are investigated. It is shown that varactors with 1:1 Hf:Zr stoichiometry and 10 nm thickness, crystallized with rapid thermal annealing (RTA) at 400°C for 60 s, show a maximum capacitance tunability of 32% at room temperature wi...
Article
Full-text available
Thin-film transistors (TFTs) based on amorphous indium-gallium-zinc-oxide (a-IGZO) have attracted vast attention for use in organic light-emitting diode (AMOLED) displays due to their high electron mobility and large current on–off ratio. Although amorphous oxide semiconductors show considerably less threshold voltage (Vth) variation than poly-sili...
Conference Paper
Ferroelectric and antiferroelectric Hf/Zr-based oxide films have recently gained interest for memory and AI applications due to their promise of low power and CMOS compatibility. As Hf/Zr-based oxides are not ‘new’ materials, this paper will start with an overview of past learning on this material system. Recent results on fundamental understanding...
Article
Full-text available
Ferroelectric hafnium oxide (HfO2) is considered as a very prospective material for applications in integrated devices, due to its considerably large spontaneous polarization and superior thickness scaling. In fact, the evolution of the ferroelectric hysteresis upon field cycling plays the important role in most applications; especially the so‐call...
Article
Full-text available
This article presents a systematic empirical modeling approach in fully depleted silicon-on-insulator (FDSOI) CMOS for large-signal simulation in power amplifier applications. The model is constructed from multibias S-parameter measurements up to 67 GHz. The frequency dispersions in transconductance and output conductance are addressed by two indep...
Conference Paper
Nearest neighbor (NN) search is an essential operation in many applications, such as one/few-shot learning and image classification. As such, fast and low-energy hardwaresupport for accurate NN search is highly desirable. Ternary content-addressable memories (TCAMs) have been proposed to accelerate NN search for few-shot learning tasks by implement...
Article
A novel hybrid antiferroelectric (AFE)-based charge trap (CT) memory is reported focusing on an amplified tunnel oxide field (ETO) via the dynamic of an AFE hysteresis dipole switching. The role of dynamic permittivity increase and the saturated polarization at the instant of the write operation are explored for enhanced ETO. The hybrid CT concept...