LaserWeldCut : an industrial oriented MEMs process fabrication project based on laser cutting and laser welding methods for glass and semiconductors

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Tyrone Simmons
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JOLY a, Lionel MERLAT b, Rüdiger SCHMITT b, Yaël DEMARTY b, Florence MOTRIER b, Laurence SEREAU c,

1 LaserWeldCut : an industrial oriented MEMs process fabrication project based on laser cutting and laser welding methods for glass and semiconductors Armel BAHOUKA a, Ludovic KOUNDE a, Marion GSTALTER a, Kilian JOLY a, Lionel MERLAT b, Rüdiger SCHMITT b, Yaël DEMARTY b, Florence MOTRIER b, Laurence SEREAU c, Jean-Louis HEITZ c a-irepa LASER b-institut franco-allemand de recherches de Saint-Louis c-critt MATERIAUX ALSACE

CONTEXT MEMS BASIC INFORMATION MEMS=Micro-ElectroMechanical Systems MEMS = process technology for tiny

Most of them are: actuators sensors: Pressure Temperature Humidity Key materials: Silicon Glass For electronic

For packaging and protection [2] MNX, micro actuator MNX [1] [3] BME280 MEMS sensor: pressure, humidity, and

2 CONTEXT MEMS BASIC INFORMATION MEMS=Micro-ElectroMechanical Systems MEMS = process technology for tiny integrated devices with mechanical and electrical components. Most of them are: actuators sensors: Pressure Temperature Humidity Key materials: Silicon Glass For electronic functions and some mechanics. For packaging and protection [2] MNX, micro actuator MNX [1] [3] BME280 MEMS sensor: pressure, humidity, and temperature measurement into a single device. Bosch [1] An Introduction to MEMS (Micro-electromechanical Systems), PRIME Faraday Partnership, ISBN [2] [3]

MEMS MARKET In the years ahead, Yole estimates that the MEMS market will nearly double and reach $22.5 billion by 2018. [4] [5] [4] Silicon as a MEMS material,r. Briseño-Rodríguez1*, P. I. Alcántara-Llanas1, A.

3 MEMS MARKET In the years ahead, Yole estimates that the MEMS market will nearly double and reach $22.5 billion by [4] [5] [4] Silicon as a MEMS material,r. Briseño-Rodríguez1*, P. I. Alcántara-Llanas1, A. P. González-Arceo1, M. Bandala-Sánchez1 1Microelectronic Systems Department, CIDESI, Av. Playa Pie de la Cuesta 702, Querétaro, México. *rodolfo.briseno@cidesi.edu.mx, Silicon as a MEMS : ttps:// [5] Glass Substrate Manufacturing in the Semiconductor Field report, July 2017, Yole Développement

TYPICAL MEMS CONFIGURATION AND MANUFACTURING PROCESS CONSIDERED Cover in glass for packaging

Valtronics [6] Materials requirements Parts to be produced in respect of all components intergrity :

electrical performance of silicon Process requirements: No auxiliary materials No intermediate

4 TYPICAL MEMS CONFIGURATION AND MANUFACTURING PROCESS CONSIDERED Cover in glass for packaging Electronics Mechanics Silicon ( or other SC) Compact planar glass encapsulated implants ( c) Valtronics [6] Materials requirements Parts to be produced in respect of all components intergrity : Heat management Geometry respect Electrical properties Glass with high biocompatibility High electrical performance of silicon Process requirements: No auxiliary materials No intermediate layers or adhesives High hermeticity, Main process considered: Cutting Welding [6]

5 Scribe and break Pros : Easy Fast Cons: 2 steps Residual stress No free form Water jet Pros: No post processing Free forms High thickness Cons: High cost Loss of matter SOME CLASSIC PROCESS FOR CUTTING [7] CO2 Laser + breaking Pros : Fast No contact No need for scribing for thickness under 1 mm Cons: No free form Cost of installation Residual stress [7] Techniques de l ingénieur: Le verre plat : Gaumes 2002

6 SOME CLASSIC PROCESS: WELDING [8] Gluing Requires glue Anodic junction Glass/Silicon: adapted silicium : bonne méthode Glass/Glass: requires additive elements Fusion junction Non local and long process Optical contacting Requires excellent surface qualities [8] J. B. Werkmeister, A. H. Slocum, Investigating different methods of bonding glass substrates

7 CHALLENGES Industries Microelectronics Micromechanics PV Helath care A new project with these requirements Laser based process for industrial cutting and welding Same laser for cutting both SC and glass

8 CONTEXT LaserWelCut is a 3 years collaborative project funded by MICA Institute Scope of the project: Built up glass and semi conductor ready to industy laser based welding and cutting processes Use on market lasers Cutting simulation Shear characterization Stress characterization Surface characterization Laser processing Welding simulation

9 PRINCIPAL AND SET UP

Free form cutting Partial absorption Local heating Temperature gradient

10 CUTTING: PROCESS FLOW Phenomenom = volumic controlled crack propagation One step and without post processing No loss of matter High speed process Free form cutting Partial absorption Local heating Temperature gradient Stress generation Crack initiation Relative mouvement Crack controlled propagation

11 SET UP: CUTTING 1st generation with moving stage 2 nd generation with scanner head

12 WELDING PROCESS: WITH FS LASER ( NEXT STEP) Welding by thermal accumulation( f> 300 khz) Beam focalization in the interface Partial dissipation of input energy Temperature raising Material fusion Welding by solidification T. Tamaki, W. Watanabe, K. Itoh, Laser micro-welding of transparent materials by a localized heat accumulation effect using a femtosecond fiber laser at 1558nm, Optics Express, vol. 14, n 22, pp , October 2006

13 WELDING PROCESS: WITH NANOSECOND PULSED LASER Mechanical clamping system

14 RESULTS FOR CUTTING

15 RESULTS CUTTING Sodocalcic glass 1 mm Detail Borosilicate 6 mm Borosilicate 6 mm Cutting of glass 500 W CW diode laser efficient for glass cutting up to 6 mm thick Regions of interest are large Free forms are possible

Maximum induced thermal tensile stress is in the order of about 150 to 200 MPa.

16 RESULTS CUTTING The stress XX ( along the scanning direction) profiles along the translation direction (y-axis; perpendicular to the scanning direction) are shown Maximum induced thermal tensile stress is in the order of about 150 to 200 MPa. Spatial temperature distribution ( Glass thickness 6 mm, laser beam velocity 2000 mm/s, laser power 196 W )

17 SILICON CUTTING V=7000 mm/min: Quality equal to mechanical cutting No thermal affected zone Rsheet Center 31 Ohm/Sq Edge =35Ohm/Sq V=13000 mm/min Few scories Good surface topology No thermal affected zone Rsheet Center 36 Ohm/Sq Edge 40 Ohm/Sq V=13500 mm/min Few scories Good surface topology No thermal affected zone Résistance carré: Center 34 Ohm/Sq Edge + 43 Ohm/Sq

18 SUM UP CUTTINGALYSE Silicon and glass free form cutting Working with a higher power laser will enable to achieve better quality and higher process speed

19 RESULTS FOR GLASS/GLASS AND SILICON WELDING NS REGIME

$without internal fracture$ interface Determine energy

20 WELDING GLASS ON GLASS Using ns 1064 nm, Pmax= 15 W Goals Obtain strong seams Obtain seams without internal fracture Strategy Determine interface Determine energy and frequency Too much fractures; process not adapted

21 WELDING GLASS ON SILICON Using ns 1064 nm, Pmax= 15 W Goal High speed process Strategy: Determination of fluence yield Determination of optimal overlap Seam Focus diameter(µm) Power (W) Frequenc y (khz) Speed( mm/s) Fluenc e (J/cm²) Overla p ( on path) (%) Overlap Transve rse (%) Seam. Seam under polarized light. Frequency: 15 khz; Welding with cracks 59 32,2 1, , Frequency: 11,25 khz Welding with «dust» Seam Focus diameter( µm) Power (W) Frequency (khz) Speed(m m/s) Fluence (J/cm²) Overlap ( on path) (%) 84 2,2 11, Seam 84: Rl: 92%; Rt: 41% Good seam

OK Electrical properties: OK Glass with high biocompatibility: OK High electrical performance of

22 RESULTS WELDING WITH Hermiticity with welding with ns pulsed laser Materials requirements Parts to be produced in respect of all components interigrity : Heat management: OK Geometry respect: OK Electrical properties: OK Glass with high biocompatibility: OK High electrical performance of silicon : OK Process requirements: No auxiliary materials : OK No intermediate layers or adhesives :OK

23 CONCLUSION AND PERSPECTIVES We demonstrated the possibility of: Cuting silicon and glass at good speed With respect of free geometry With respect of surface quality With respect of electrical properties Using laser crack controlled propagation with very common diode laser Welding Glass on silicone with «good» hermeticity We have to work on: Cutting: Seeting up higher power laser to increase the process speed Welding: Use fs laser to preserve integrity of material Obtain better seams

24 THANK YOU FOR YOUR ATTENTION Armel BAHOUKA 15/11/2017

25 15/11/2017

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