DARPA-PA-19-04-03.pdf

DARPA-PA-19-04-03

Solicitation No. DARPA-PA-19-04-03 Microsystems Exploration Topic (μE)

Tunable Ferroelectric Nitrides (TUFEN)

I. Topic Description The Defense Advanced Research Projects Agency (DARPA) is issuing a Microsystems Exploration topic (μE) inviting submissions of innovative basic or applied research concepts in the technical domain of ferroelectric nitride material deposition, ferroelectric property characterization, and evaluating the operating window of tunable ferroelectric derived electro-active properties in nitride materials and advanced ferroelectric nitride devices. This μE is issued under the Program Announcement for Microsystems Exploration, DARPA-PA-19-04. All proposals in response to the technical area(s) described herein will be submitted to DARPA-PA- 19-04 and if selected, will result in an award of an Other Transaction (OT) for a prototype project not to exceed $1,000,000.

A. Introduction Scandium (Sc)-doped AlN is a popular material for a number of device applications, such as RF filters, piezoelectric actuators, ultrasonic sensors, microphones, and oscillators. In addition to the advantageous piezoelectric and complementary physical properties of AlN-based materials, the relatively low synthesis temperatures make such materials particularly attractive for integration with electronics platforms when compared with other piezoelectric materials, especially perovskite oxides. Recent work1 has demonstrated the emergence of ferroelectric switching behavior in highly Sc-doped AlN thin films when the Sc content exceeds ~30%. Such a ferroelectric nitride could enable an enormous number of potential applications in a wide variety of devices, including monolithic integration of ferroelectric non-volatile memory on CMOS, ferroelectric resistive memory, filters (e.g. bulk acoustic wave and surface acoustic wave), tunable RF components, switchable electro-optical components, non-volatile logic, neuromorphic memory, tunable two-dimensional electron gas (2-DEG) heterostructures, and pyroelectric and thermal energy scavenging devices. Although ferroelectric switching has been demonstrated in a limited scope laboratory setting, further study is needed to more systematically quantify the thickness and doping ranges that exhibit ferroelectric behavior, identify the robustness and reproducibility of the ferroelectric response, and demonstrate ferroelectric nitrides as a technologically useful material.

B. Objective/Scope The goal of the TUFEN μE is to determine and demonstrate the range of physical conditions for ferroelectric behavior in doped nitride materials and to characterize the effects of physical dimensions, material composition, and processing conditions. Furthermore, this effort will demonstrate device functionality and reliability characterization in concert with the ferroelectric properties of these nitride materials. TUFEN will be a two-phase program; the first phase will focus on material characterization and process parameter optimization, while the second phase will focus on revolutionary device demonstrations.

TUFEN places strong emphasis on demonstrating nitride materials with a ferroelectric response integrated with technologies that are capable of transitioning into commercially viable

1 S. Fichtner, et al., J. Appl. Phys. 125, 114103 (2019); https://doi.org/10.1063/1.5084945 manufacturing environments, especially compatibility with standard CMOS processes.

Accordingly, proposals must describe the nitride ferroelectric deposition technique(s) including processing parameters, the anticipated range of doping levels and film thicknesses (i.e. 1 nm to 1 µm is of interest), and the corresponding measurement of relevant ferroelectric, dielectric, piezoelectric, pyroelectric, and other as-deposited and processed material properties (e.g. residual stress, crystallinity, defect concentrations, etc.).

Phase 2 device demonstrations should illustrate the feasibility of fabricating functional devices and showcase the use of the ferroelectric response to enhance device operation. Device type is up to the discretion of the proposer; possible examples include (but are not limited to) non-volatile memory, monolithic integration of ferroelectric non-volatile memory on CMOS, ferroelectric resistive memory, tunable RF components (e.g. filters), switchable electro-optical components, and tunable two-dimensional electron gas heterostructures. Performers must demonstrate device functionality in concert with the ferroelectric properties of the material.

TUFEN will explore multiple techniques and approaches to develop a series of ferroelectric property phase diagrams identifying the range of useful properties in concert with initial device demonstrations exploiting the ferroelectric properties that may be used to determine the application space for future development.

C. Structure Proposals submitted to DARPA-PA-19-04 in response to this μE topic must be UNCLASSIFIED and must address two independent and sequential project phases: a Phase 1 Feasibility Study (base) and a Phase 2 Proof of Concept (option) as listed in Section D. The periods of performance for these phases are 9 months for the Phase 1 base effort and 9 months for the Phase 2 option effort.

Combined Phase 1 base and Phase 2 option efforts for this μE topic should not exceed 18 months.

The Phase 1 (base) award value should not exceed $350,000. The Phase 2 (option) award value should not exceed $650,000. The total award value for the combined Phase 1 and Phase 2 is limited to $1,000,000. Phase 1 studies will be evaluated to determine the feasibility of the approach and whether to select the option for Phase 2.

Proposals should clearly detail:

The proposed and any initial results for demonstration of deposition method(s) including the range of thicknesses to be evaluated along with a description of the viable range of doping levels that may be achieved and an explanation of how the technique scales toward a capability compatible with conventional leading edge and future CMOS processing.

A proposed demonstration device structure and fabrication process that takes advantage of the ferroelectric characteristics of a doped nitride material.

The proposed approach and any initial results for modelling and simulating material and/or device properties.

The proposed and any initial results for measurement techniques for crystallinity, ferroelectric, dielectric, piezoelectric, pyroelectric, defect concentration, and other material related properties as well as the proposed measurement techniques and capabilities of tuning or modifying as-deposited or processed film characteristics (e.g. residual stress, crystallinity, dopant type, doping level, etc.).

The proposed approach to characterize reliability properties such as short-term and long-term electric field induced breakdown, cycling endurance, and polarization retention and the metrics used for comparing with existing commercially viable ferroelectric materials.

The proposed device characterization methods to demonstrate ferroelectric behavior, including performer defined application relevant metrics (e.g. switching cycle lifetime, switching speed, mechanical quality factor, coupling coefficient, etc.).

Phase 1 (Study) should report summary data to determine the feasibility of the approach. Criteria for the feasibility assessment includes, but is not limited to, crystallinity and texture measurements on deposited films and phase diagrams plotting the evolution of ferroelectric and dielectric properties across a range of film compositions and thicknesses. Phase 2 (Proof of Concept) should include experimentally verified data of material and electrical properties, a series of phase diagrams plotting the evolution of properties, and device demonstrations highlighting the ferroelectric characteristics (e.g. ferroelectric switching cycle lifetime, switching speed, polarization retention, polarization voltage hysteresis, capacitance and dielectric loss hysteresis, piezoelectric displacement hysteresis, or performer defined application relevant metrics) of the nitride materials over a wide range of film thicknesses relevant to existing and future integrated circuit process nodes.

The Government reserves the right to award all, some, one, or none of the options on the agreements(s) of the Phase 1 performers based on available funding, Phase 1 technical performance, and an assessment of the feasibility of the approach.

D. Schedule/Milestones Proposers must address the following research project objectives, metrics, milestones, and deliverables in their proposals. A Schedule of Milestones and Payments excel spreadsheet has been provided as an attachment to this solicitation. Proposers are required to submit this attachment with their proposal submission, with priced milestone payments consistent across the Task Description Document (TDD) and the Vol. 2 – Price Volume. The task structure must be consistent across the proposed schedule, Task Description Document (TDD), and the Vol. 2 - Price Volume.

If selected for award negotiation, the fixed payable milestones will be directly incorporated into Attachment 2 of the OT agreement (“Schedule of Milestones and Payments”). Please see the sample OT for Prototype provided as an attachment to DARPA-PA-19-04.

For planning and budgetary purposes, proposers should assume a program start date that is 90 days from μE topic announcement on fbo.gov. Schedules will be synchronized across performers, as required, and monitored/revised as necessary throughout the program.

Fixed milestones for this program must include:

Month Milestone Phase 1 – Material Characterization

3 Interim report detailing Overall technical approach and model and simulation results supporting technical claims Evaluation of the deposition technique (including supply chain challenges) illustrating capability of achieving the doping levels necessary to achieve ferroelectric response in nitride material

Crystallinity and microstructure as a function of film thickness and/or doping level

6 Interim report detailing Ferroelectric, dielectric, and piezoelectric properties as a function of film doping level Ferroelectric, dielectric, and piezoelectric properties as a function of film thickness 9 Final report detailing Phase 1 summary data for evaluating Phase 2 transition decision to include:

Phase diagrams plotting the evolution of ferroelectric, dielectric, and piezoelectric properties across a range of film compositions, doping levels, and thickness

Demonstration of ferroelectric, dielectric, and piezoelectric properties as a function of film thickness and doping level

Evaluation of process technique for inclusion in conventional semiconductor fabrication facility

Measurements of film stress including either experimental or simulation results identifying tuning or modifying the as-deposited residual film stress

Phase 2 – Device Fabrication and Characterization 12 Interim report detailing

Material properties as a function of electric field and frequency of operation Ferroelectric property lifetime and endurance Approach for device demonstration leveraging ferroelectric properties of the material 15 Interim report detailing

Evaluation of pulse switching operation Evaluation of limits of ferroelectric behavior in doped nitride materials including but not limited to minimum and maximum thickness, doping, and frequency of operation

Device patterning approach and results Initial device integration and operation

18 Final Report detailing Material and electrical property characteristics Phase diagrams plotting evolution of composition vs. physical properties Integrated device demonstration

Delivery of a minimum of nine (9) devices for government evaluation

All proposals must include the following meetings and travel in the proposed schedule and costs:

To foster collaboration between teams and disseminate program developments, a two-day

Principal Investigator (PI) meeting will be held approximately every six months, with locations split between the East and West Coasts of the United States. For budgeting purposes, plan for three two-day meetings over the course of 18 months: two meetings in the Washington, D.C. area and one meeting in the Seattle, WA area.

Regular teleconference meetings will be scheduled with the Government team for progress reporting as well as problem identification and mitigation. Proposers should also anticipate at least one site visit per phase by the DARPA Program Manager during which they will have the opportunity to demonstrate progress towards agreed-upon milestones.

Phase Metrics By the end of each phase, the materials and devices must have achieved the following corresponding metrics:

Property Metric Phase 1 – Material Characterization

Material quality

Single phase (>90% ferroelectric phase) AlScN as shown by X-ray diffraction data with full-width-half-maximum rocking curve values < 2°

Surface characterization showing maximum surface roughness < 20nm RMS

Film thickness range targeting an operating range of 10 nm – 1 µm Film stress ranging from -500 to +500 MPa

Composition Direct composition measurements demonstrating a range of doping values

Direct composition measurements through thickness of film with <2% drift in composition profile across film cross section

Direct composition measurements across lateral film dimensions demonstrating no more than 3% deviation per 100 mm

For all electrical properties (e.g. ferroelectric, dielectric, piezoelectric, etc), performers will identify regions of the phase diagram where the properties would be of interest for a range of applications.

Electrical Properties

The values listed below are representative targets that would be of interest within the phase diagrams.

Dielectric constant, ε33, values of > 12 Piezoelectric coefficient, e31,f < -1 C/m2

Remnant polarization, Pr, values > 15 µC/cm2

Coercive field, Ec, values no greater than 4 MV/cm, with a target of <1 MV/cm

Polarization switching speed of <1 μs.

Tan δ values < 0.02 at 10 kHz

Property Metric Phase 2 – Device Characterization

Electrical Properties

For all electrical properties, performers will identify regions of the phase diagram identifying the limits of ferroelectric behavior.

Switching Demonstrated ferroelectric switching in a device with no more than 4 MV/cm applied field, targeting <1 MV/cm

Demonstrated ferroelectric switching in a device with <1 μs polarization switching time.

Demonstrated ferroelectric switching in a device with 2Pr > 30 μC/cm2 polarization switching

Demonstrate ferroelectric switching at temperatures >150°C Lifetime Demonstration of a minimum of 100,000 switching cycles with < 5% reduction of properties Demonstration of Pr >15 μC/cm2 for a retention time of > 100 hr Characterization of the short-term and long-term electric field induced breakdown User

Defined 2-3 proposed device relevant metrics (e.g. for resonators Q and kt would be of interest)

E. Deliverables Phase 1 deliverables will be reports detailing the results of the Phase 1 milestones as indicated in Section C.

Phase 2 deliverables include reports detailing the results of the Phase 2 milestones as indicated in Section C. Additionally, a minimum of nine (9) materials/devices (e.g. die size of 2mm x 2mm, sections of a wafer, full wafer, etc.) shall be provided for independent government evaluation. The delivered materials/devices should cover a range of thicknesses and doping levels and should include a minimum of 3 of each types of materials/devices listed below.

1. Blanket films for XRD, XRF, and other physical characterizations.

2. Capacitor structures with accessible electrodes that can be used to electrically test ferroelectric switching response.

3. Device structures with accessible electrodes that can be used to verify electrical and/or mechanical properties in conjunction with the ferroelectric characteristics.

II. Award Information Selected proposals that are successfully negotiated will result in award of an OT for prototype project. See Section 3 of DARPA-PA-19-04 for information on awards that may result from proposals submitted in response to this notice.

Proposers must review the model OT for Prototype agreement provided as an attachment to DARPA-PA-19-04 prior to submitting a proposal. DARPA has provided the model OT in order to expedite the negotiation and award process and ensure DARPA achieves the goal of Microsystems Exploration, which is to enable DARPA to initiate a new investment in less than 902 days from

2 To take into consideration the holiday break for this topic announcement, there is a two (2) week black out period added to the 90 day award timeline. The blackout period is 23 December 2019 through 3 January 2020 and takes each μE topic announcement. The model OT is representative of the terms and conditions that DARPA intends to award for all Microsystems Exploration Awards. The task description document, schedule of milestones and payments, and data rights assertions requested under Volumes 1, 2, and 3 will be included as attachments to the OT agreement upon negotiation and award.

As discussed in DARPA-PA-19-04, Section 5, “Application and Submission Information,” paragraph 5.1.4, Proposers may suggest edits to the model OT for consideration by DARPA and provide a copy of the model OT with track changes as part of their proposal package. It is strongly encouraged that Proposers include comments providing rationale for any suggested edits of a non-administrative nature. Suggested edits may be rejected at DARPA’s discretion. In order to ensure that DARPA achieves the Microsystems Exploration goal of award within 90 days from the posting date of the μE topic announcement, DARPA reserves the right to cease negotiations if the parties fail to reach agreement on OT award terms and conditions within this time period. If edits to the model OT are not provided as part of the proposal package, DARPA assumes that the proposer has reviewed and accepted the award terms and conditions to which they may have to adhere and the sample OT agreement provided as an attachment, indicating agreement with the listed terms and conditions applicable to the specific award instrument.

III. Eligibility See Section 4 of DARPA-PA-19-04 for information on who may be eligible to respond to this notice.

IV. μE Topic Responses Responses to this μE topic must be submitted as full proposals to DARPA-PA-19-04 as described therein. All proposals must be unclassified.

A. Proposal Content and Format All proposals submitted in response to this notice must comply with the content and format instructions in Section 5 of DARPA-PA-19-04. Other than providing proposed milestone amounts in the Schedule of Milestones and Payments excel spreadsheet, there shall be no changes to the research project objectives, metrics, and milestones, or to the deliverables, described therein. All proposals must use the templates provided as Attachments to the PA and follow the instructions therein. Information not explicitly requested in DARPA-PA-19-04, its Attachments, or this notice may not be evaluated.

B. Proposal Submission Instructions See Section 5 of DARPA-PA-19-04 for proposal submission instructions.

C. Proposal Due Date and Time Proposals in response to this notice are due no later than 4:00 PM on December 12, 2019. Full proposal packages as described in Section 5 of DARPA-PA-19-04 must be submitted per the instructions outlined therein and received by DARPA no later than the above time and date.

place during proposal evaluation. This blackout period impacts only the evaluation and selection stage. The period of time allotted for the negotiation of selected proposals will remain 30 days.

Proposals received after this time and date will not be reviewed. Proposers are warned that the proposal deadline outlined herein is in Eastern Time and will be strictly enforced.

V. Proposal Evaluation and Selection Proposals will be evaluated and selected in accordance with Section 6 of DARPA-PA-19-04.

Proposers will be notified of the results of this process as described in Section 7.1 of DARPA-PA- 19-04.

VI. Administrative and National Policy Requirements See Section 7.2 of DARPA-PA-19-04.

VII. Point of Contact Information Ronald G. Polcawich, Program Manager, DARPA/MTO, TUFEN@darpa.mil

VIII. Frequently Asked Questions (FAQs) All technical, contractual, and administrative questions regarding this notice must be emailed to TUFEN@darpa.mil. Emails sent directly to the Program Manager or any other address may result in delayed or no response.

All questions must be in English and must include name, email address, and the telephone number of a point of contact. DARPA will attempt to answer questions publically in a timely manner;

however, questions submitted within 7 days of the proposal due date listed herein may not be answered.

DARPA will post an FAQ list under the μE topic on the DARPA/MTO Opportunities page at (http://www.darpa.mil/work-with-us/opportunities). The list will be updated on an ongoing basis until one week prior to the proposal due date. In addition to the FAQ specific to this notice, proposers should also review the Program Announcement for Microsystems Exploration General FAQ list on the DARPA/MTO Opportunities page under the Program Announcement (DARPA-

PA-19-04).

To aid in the proposal preparation process, a Proposal Preparation Checklist and Tips document has been provided with the μE topic announcement on fbo.gov. This document can also be found along with the FAQ posted on the DARPA/MTO Opportunities page at (http://www.darpa.mil/work-with-us/opportunities).

http://www.darpa.mil/work-with-us/opportunities?tFilter=&oFilter=5&sort=date http://www.darpa.mil/work-with-us/opportunities?tFilter=&oFilter=5&sort=date