Wafer-Level Glass Molding of Chalcogenide Glasses High Volume Infrared Optics Production

Wafer-Level Glass Molding of Chalcogenide Glasses High volume infrared optics production

EPIC Meeting on Wafer Level Optics Neuchâtel, CH, Nov. 7th – 8th 2019

Tim Grunwald, Jan-Helge Staasmeyer, Gang Liu

➔ Largest organization for applied research in Europe

Fraunhofer Society ◼ Founded in 1949 ◼ Legal form: nonprofit association ◼ Headquarter in Munich, Germany

Goal ◼ Contract research for economy and society ◼ Transferring fundamental research to industrial application

459 Employees, thereof 31 m € operating budget, 214 permanently thereof 13 m € Industry projects

Aachen

Fraunhofer IPT is certified according to DIN EN ISO 9001:2015

Aspherical Optics Freeform Optics Lighting Optics ◼ Wide range of possible geometries ◼ Accuracies can be adjusted according to the field of application: – Imaging Diffractive Optics Micro Optics Infrared Optics – Lighting – Laser Optics ◼ High reproducibility/ repeatability as a consequence of the Cylindric Lenses Lens Arrays Wafer Optics molding process

Chalcogenide glass

Low-Tg-Glass

Soda-lime glass

Borosilicate glass

Fused silica

Customer-specific glass types

T [°C] 0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500

Uncooled Infrared Imaging Qty. Systems Mobile 2,000,000 Thermography Zivilcommercial < 1 k$/Stück < 1 k$/ piece Source: FLIR Militärischmilitary > 10> 10 k$/ k$/Stück piece 1,500,000

Automotive 1,000,000 Night Vision Source: Autoliv

500,000 Low-Cost Presence 0 Detection 2016 2017 2018 2019 2020 2021 2022 Source: Panasonic

Motivation The rising demand for low-cost, aspheric infrared optics can only be met with a scalable replicative production technology such as precision glass molding.

IV V VI ◼ Covalently bonded chalcogenides of Carbon Nitrogen Chalcogen elements of group IV and V Group group C N O ◼ Cost-effective synthesis by glass melting compared to Carbon Nitrogen Oxygen crystal growth processes Si P S Silicon Phosphorus Sulfur ◼ Characteristic properties: Ge As Se Germanium Arsenic Selenium Sn Sb Te Chalcogenide glass Optical glass Tin Antimony Tellurium Trade name IG6 / IRG26 IG5 / IRG25 N-BK7 ≥9 Oxides Composition As2Se3 Ge28Sb12Se60 (SiO2 , B2O3 ,…) Transmission 1 – 12 1 – 11 0,35 – 1,9 [µm] Refractive 2,8 2,6 1,5 index [1] Tg [°C] 185 285 557 훼 [10-6/K] 20,7 14 7,1

Force Precision Glass Molding Temperature Mold Temperature Glass Mold Position

Pros Cons Low-costs due to Process scalability development Temperature, Force, Position Force, Temperature, effort Zeit Material efficiency Time-to-Market

Umformung Kühlung & Erwärmen Heating Soaking Molding EntnahmeCooling Molded Lens

© WZL/Fraunhofer IPT Seite 8 Current Developments Project Overview »SKALIR« 2017 - 2020 ◼ Project target: “Scalable replication of infrared lenses” – Cost reduction for precision molded infrared optics by a factor of 5 – 10 due to scalable mold concepts.

Single-Cavity Multi-Cavity Wafer Level

◼ One lens per cycle, ◼ Rotational symmetric ◼ Lenses smaller Ø5 mm however also large or lenses smaller Ø20 mm complex lenses feasible

~100x 2-20x 1x Lenses per cycle

Lenses per cycle

Design Mold Molding process

Glass Shrinkage Service Life-time

Glass Fracturing

Glass Flow

Mold Machining

Wafer-Level Glass Molding

Crack probability ◼ Glass breakage observed more frequently with wafer- based processes compared to ball preforms ◼ Expansion and shrinkage while heating or cooling induce a higher risk of breakage, especially in the case of CTE-mismatches (tool/glass)

CTE comparison Cooling shrinkage (center) Cooling shrinkage (outer dia.) Borosilicate Glass Tungsten Carbide Soda-Lime Glass Chalcogenide Glass Aluminum Center line 0 5 10 15 20 -6 -1 훼 [10 K ] Approximate Tensile uniform shrinkage stresses in the center cause glass fracture

) 휎푢 at high strain-rate

푢 휎 휎푢 at low strain-rate ≈ 100% break line Flexural strength ≈ 0% break line

Ultimate stress( Small deformation fracture (Brittle) Big deformation fracture (Transition) No fracture (Ductile) Temperature Weibull statistics ◼ Temperature and strain-rate determines 휎 , which 푢 (fracture probability 푃 ) determines the fracture behavior of glass 푓 휎 푚푉 Both brittle fracture and transition fracture of glass − ׬ 푑푉 ◼ 푉 휎 follows Weibull statistics, however their Weibull 푃푓 = 1 − 푒 0 푉 푓표푟 휎 > 0 parameters (푚푉 and 휎0 푉) are different

◼ Chalcogenide glass is much (Tg)

Silica glass* more fragile than silica glass (MPa)

푓 ◼ The 휎 -휂(temperature) curve 휎 100 푓 of chalcogenide glass is also different from silica glass *Modeling Fracture Behavior in Precision Glass Molding; Gang Liu; RWTH Aachen University; 2018 ◼ Further study on the fracture of chalcogenide

glass is necessary Flexural Flexural strength

**Temperature dependence of the mechanical behavior of a GeAsSe glass; E. Le Bourhis et al., Scripta Materialia 45, 2001.

Chalcogenide glass** 20

0 Viscosity 휂

© WZL/Fraunhofer IPT Seite 14 Our Solution and Development Goal FEM-Simulation with advanced material models Finite Element Method Simulation with advanced material models for chalcogenide glass Functionality ◼ Visualization of glass flow

→ Mold design optimization

◼ Prediction of lens shrinkage

→ Aspheric mold compensation

◼ Calculation of fracture probability

→ Process optimization

What we can offer: − Simulation studies in M.Sc. glass forming Tim Grunwald Head of Department “Fine Machining and − Process development Optics” − Prototype Fraunhofer Institute IPT Steinbachstrasse 17 • D-52074 Aachen manufacturing Phone.: 0241 / 8904 – 408 [email protected] What we are looking for: − Application cases − Inspiration for new developments M.Sc. Jan-Helge Staasmeyer − Partners for bilateral Group Manager “Optics” or public-funded Many thanks to: Fraunhofer IPT projects Steinbachstraße 17 • D-52074 Aachen Phone: +49 241 / 8904 - 568 [email protected]

GOLD SPONSOR DINNER SPONSOR

SILVER SPONSORS

BRONZE SPONSORS

EU initiatives funded by www.photonics21.org