VCSELs. Key components for optical interconnects October

Transcription

1 VCSELs Key components for optical interconnects October 2010

2 Outline 1. Overview Key VCSEL properties and current VCSEL markets projections for VCSEL based optical interconnects 1999 technology roadmap for VCSELs Fundamental limits G VCSELs Electro-optical properties Reliability 4. Optical USB: Mass fabrication of VCSELs 5. Summary Producing more Costing less Company Confidential 2

3 Key Properties Vertical Emission On Wafer testing Simple Assembly Small (80'000/3"Wafer) High Reliability and high modulation speed Symmetric beam Most efficient conversion electrical to optical power (~1 mw) 2D arrays optional Wavelength range 680 nm nm Company Confidential 3

4 Optical Datacom and O/I-Markets Volum me [units/year] Intra/ interchip LightPeak VCSELs Smart Cables LAN/SAN FTTH Edge Emitter 10 5 FO Amplifiers Distance [m] Company Confidential 4

5 Other VCSEL Markets Computer mouse Finger navigation Encoder Gas Sensing Atomic Clocks FT-Spectroscopy Illumination Consumer: Large volumes (100M+) Industrial: Single mode & polarization stable Company Confidential 5

6 1999 Technology Roadmap European Comission 1999 projections for VCSEL arrays for 2007: 2D VCSEL arrays Bottom Emission Aggregate Bit Rate 33 Tbit/s Single Mode Operating current/vcsel ~ 0.5 ma Power consumption/vcsel ~ 0.6 mw Target Applications: Intra- and inter-chip interconnects Technology Roadmap, European Comission, Advanced research initiative in microelectronics MEL-ARI OPTO, 2nd edition, Sept : Intra-chip and inter-chip interconnects still electrical Company Confidential 6

7 Electrical vs. optical interconnects Electrical Optical Fundamental limit * B ~10 6 A/l 2 Gbit/s Example: A = 1 cm 2 l = 1000 cm B ~ 1 Gbit/s HDTV Signal: 1920 x 1080 ~ 2 Gbit/s No comparable scaling limits * See: D. A. B. Miller, "Physical Reasons for Optical Interconnection," Special Issue on Smart Pixels, Int l J. Optoelectronics 11 (3), (1997) Company Confidential 7

8 10.3 Gb/s VCSEL TOSA Tektronix scope DSA8200 (plug-in 80C08C) Vitesse 7985 VCSEL driver T=-20 C, I bias ~ 6mA, ER=5dB T=25 C, I bias ~ 6mA, ER=5dB T=85 C, I bias ~ 8.5mA, ER=5dB 30% Margin 30% Margin 30% Margin intensity [dbm] EU-02-G1-2-6, 70 C, I bias =8.5mA λ=853.0nm, λ Peak, RMS =0.268nm Good temperature stability Large mask 10.3 Gb/s Narrow linewidth (< 0.3 nm) Application: Gigabit Ethernet wavelength [nm] Company Confidential 8

9 VCSEL Reliability requirements failure rate wearout failures σ infant failures random failures MFT time (log scale) Optical interconnects: MFT > 30 70C Random failure rate < 100 ppm over product lifetime Negligble infant failure rate Company Confidential 9

10 Random failure Rate - 10G VCSEL: VCSELs from 10 wafers No failure - Similar VCSEL: VCSELs from 96 wafers No failure Ambient temperature ppm levels over 1 year 25 C < C < C < 176 Company Confidential 10

11 Additional reliability tests - VCSEL chips - Consumer applications Biased 85 /85 Low temperature (-40C) Damp heat cycles Thermal shocks (-40, 25, 125C) Mixed gas Output 6mA Output 6mA [µw] A 1 a 1 a A 1 A 1 A a a B b C b 13 c D E F G H I e J K c L M b 2 C e i 3 c k l m d f g 10 h i j d e B C 5 6 f g 7 h D k l 2b 3 D F 7 G m B c 8 9 i j E F G H k Ll I 4 d 5 6 b C c E D F G F 7 d 7 8 9I 10 J K e f h m J K L M g i 11 g Hh I 12 J j k l K Ll 13 mm M b c d k e f g h i j k l m Operating conditions: T amb =55 C, I=6mA Time [hours] Operating conditions: 85 C/85%r.h./6mA (2 wafers, dev.) Time [hours] Company Confidential 11

12 High volume VCSEL manufacturing Each week ~ 600 addtl. VCSELs on reliability test Efficient reliability testing procedures Strict SPC Control required Many in-line controls Continuous cost reduction Smaller die size Efficient processes Testing capabilities Company Confidential 12

13 Mesa etch depth Time Series Plot of etch depth (nm) etch depth (nm) Target etch depth: 2950nm Data of >1600 wafers Index Mesa etch depth 3020 Mean 2952 StDev N Frequency etch depth (nm) Company Confidential 13

14 Cost reduction Number of VCSEL chips per wafer Tenfold increase in number of VCSELs per wafer over the last 10 years Trend to continue in the coming years Company Confidential 14

15 Summary VCSELs for optical interconnects: Modulation speed > 10 Gbit/s now (25Gbit/s) Very low FIT rates, high reliability High volume manufacturing capability (100M+/year) Cost efficient manufacturing More devices / wafer (Dicing) Bigger Wafers (uniformity) Efficient processes Testing Capabilites Process control Many in line controls 6 Sigma tools Company Confidential 15