MIDISPPI. «MicroDispositif de test en Silicium nanoporeux pour le Packaging Intelligent» ANR Project N. Pous, F. Mailly, P. Nouet, L.

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1 Projet DEMAR LIRMM MIDISPPI «MicroDispositif de test en Silicium nanoporeux pour le Packaging Intelligent» ANR Project 006 N. Pous, F. Mailly, P. Nouet, L. Latorre MEMS Reliability Workshop - Toulouse, may 9-30, 008

2 LIRMM The MIDISPPI Project ANR MIDISPPI Project 006 IEF IMS LIRMM - NXP Academic Partners: IEF (Orsay) IMS (Bordeaux) LIRMM (Montpellier) Industrial Partners: NXP Design and realization of a smart packaging : Integrating microsensors in the cap for the monitoring of the package internal environment. Various test devices will be integrated: Temperature, Pressure and Humidity sensor. The ultimate goal is to obtain a «zero-defect» final test method. Calibration & compensation functions

3 Context: The PiCS substrate LIRMM ANR MIDISPPI Project 006 IEF IMS LIRMM - NXP 3 RF passive component Sensor conditionning IC Silicon cap IC 1 RF substrate MEMS (main function) Temperature sensor Pressure sensor (Pirani)

4 Context: The PiCS substrate LIRMM ANR MIDISPPI Project 006 IEF IMS LIRMM - NXP 4 PiCS 5-50nm of SiN x /SiO One polysilicon layer interconnect levels (Al) oxides (SiO ) layers +1 passivation (SiN x ) layer MEMS compatibility TMAH /FSBM : fabrication of suspended structures PolySi : Thermal and mechanical sensitivity Al ox opennings SiN x ox 1 polysi SiN x /SiO

5 LIRMM MEMS on PiCS ANR MIDISPPI Project 006 IEF IMS LIRMM - NXP 5 Magnetometers Accelerometers Microphones

6 Temperature sensor LIRMM ANR MIDISPPI Project 006 IEF IMS LIRMM - NXP 6 0,00144 Use of PiCS polysilicon (resistors) Measure of thermal coefficient between 0 and 90 C (LIRMM) Good linearity (r > 0.999) 0.13%/ C < CTR <0.14 %/ C CTR (/ C) 0,0014 0, , , , ,0013 puce 1 puce 0, R 0 C (Ω) Confirmed by IMS measurements between -50 et 10 C

7 Pirani Gauge Working Principles LIRMM ANR MIDISPPI Project 006 IEF IMS LIRMM - NXP 7 Use of a suspended resistor as a heater (FSBM) Thermal equilibrium: Heat conduction into materials to the substrate Radiation losses (usually negligible) Heat conduction or natural convection into surrounding gas (related to the pressure) Gas thermal conductivity: log(λ gaz ) Negligible for p<<p tr Constant (λ 0 ) for p>>p tr λ gaz ( p) λ = 0 p p + p tr log(λ 0 ) log(p) techniques for pressure measurement Temperature measurement at constant power Power measurement at constant temperature log(p tr )

8 Transition pressure LIRMM ANR MIDISPPI Project 006 IEF IMS LIRMM - NXP 8 Related to molecule free minimal path (l) : l = kt pπa pour N, πa =0,43nm 0 C p tr as a function of molecules speed and air gap: p tr wtb = λ0 ( w + z) dv T b R. Puers et al, Sens. Actuators A (00), p tr as a function of air gap and l p tr = v Cv RT lp d d + l( α E 1) M. Kimura et al, Microelectronics Journal 38 (007),

9 Thermal Equilibrium LIRMM ANR MIDISPPI Project 006 IEF IMS LIRMM - NXP 9 G tot = G solid + G rad + G gas p p + p tr log(g tot ) Under vaccum (p<<p tr ) G solid + G rad At p>>p tr G tot puis G gas log(g gas ) log(g solide +G rad ) log(p tr ) log(p)

10 Prototyping LIRMM ANR MIDISPPI Project 006 IEF IMS LIRMM - NXP 10 Prototype features R 0 C = 390Ω, CTR=0,138%/ C Length =100μm, width d polysi =5μm Cross-section area : s tot ~ 104μm Beam exchange surface : S tot ~ 78500μm S SiNx # 10μm 1.5 μm 0.5 μm 0.3 μm 0.8 μm S ox #.4μm S ox1 # 0.9μm d polysi μm μm μm Temperature regulation (T c =316 C) R T c R T ) = R (1 + CTR. T ) = 560Ω ( 0 C C

11 Conditionning Circuit LIRMM ANR MIDISPPI Project 006 IEF IMS LIRMM - NXP 11 R 1 =560Ω Two stable states : All potentials are zero (impossible due to noises and offsets) I 1 large enough to heat the Pirani resistor, giving R Pirani # R 1 and T Pirani # T c et V + # V - AD60 (G=1000) I V S1 V S R 1 R 1 I I 1 R 1 R Pirani

12 Experimental results LIRMM ANR MIDISPPI Project 006 IEF IMS LIRMM - NXP 1 V S (V) sauts de la jauge de référence 0,01 0, p (mbar) T T V V + S1 Pirani Pirani V = G( V + V R1 R = CTR R S V = 316 C ε ( R R ) 1 4R 1 ) V ( VS GV. Pirani S ).4R. CTR. R 0 C 1. 0 C S 0 C V V S S =,5V = 7,14V ε = 5,3 C ε = 4,6 C G G solide tot + G T rad Pirani T Pirani PJ 0 C PJ 0 C,9.10 = 91.3,8.10 = 90,5 3 = 7,85.10 = 9, W / K W / K G air 6, W / K h air 876W. m K 1

13 Modeling (Matlab/Simulink) LIRMM ANR MIDISPPI Project 006 IEF IMS LIRMM - NXP 13 noise + offset V+ V Hz +10V V S1-10V I = I 0 e V S1 V kt S 1 + V = R 1 I V = R PiraniI 1 V+ 3 5 V S1 + - V S V- AD 60 G tot = G solide R th + G rad 1 = G tot + G gaz p p + p tr R Pirani ( + ( T + ΔT )) = R0 C 1 α 0 R Pirani diode 6 I 1 Pirani 4 p 1a R th 1b ΔT 1c R Pirani p I 1 I I 1 ΔT = P J Rth Rth = RPirani I1 1+ jωτ 1+ jωτ rq : τ = 1 bar I I 1 = I 3R 1 R + R1 + R = I 3R + R 1 1 R Pirani Pirani Pirani V S = R1 I

14 Simulation vs Measurements LIRMM ANR MIDISPPI Project 006 IEF IMS LIRMM - NXP V S (V) ,01 0, p (mbar) p tr = 1 mbar

15 LIRMM Porous Silicon Humidity Sensor ANR MIDISPPI Project 006 IEF IMS LIRMM - NXP 15

16 LIRMM Porous Silicon Humidity Sensor ANR MIDISPPI Project 006 IEF IMS LIRMM - NXP 16

17 Conclusion & Further work LIRMM ANR MIDISPPI Project 006 IEF IMS LIRMM - NXP 17 Approach strengths Environment parameters monitoring Fail information or feedback to conditioning circuit Use of PICS substrate (low-cost integration) Sensors level Thermal conductivity of air and materials needs to be studied Modeling (porous silicon absorption, heat transfer ) Optimization & characterization Support from FEM System level Integration issues (packaging) Design & Integration of conditioning circuits