1. Thermoreflectance microscopy and spectroscopy on integrated circuits
M. Bardoux, C. Boué, C. Filloy, D. Fournier, G. Tessier
UPR A005 CNRS, ESPCI, 10 Rue Vauquelin, Paris

2. 1 Thermoreflectance under visible illumination

3. DR= DT CCD thermoreflectance imaging 4f < 40 Hz CCD White lamp
Optical measurement of DR
(at virtually any wavelength)
Filter
measurement of DT
Microscope
Pow.1: f
Circuit

4. CCD thermoreflectance imaging
FoR j
FoRamb t
FoDR I1 I2 I3 I4
4f < 40 Hz
CCD
White lamp
Filter
DR around 10-5
DT around 0.1 K
Resolution 300 nm
Microscope
Amplitude
Pow.1: f
Circuit

5. Transistor arrays (ST Microelectronics)
Not leaky structures:
leaky structures:
13 mm
125 mm
IDS = mA, F=1 Hz
l=518 nm
125 mm

6. Vertical Cavity Surface Emission Lasers (VCSELs)
M Bardoux, ESPCI, S. Bouchoule, A. Bousseksou, LPN
Laser emission
(1.5 mm)
VCSEL Cleavage
Vertical temperature distribution

7. 90 mm 250 mm Side view (substrate, mirror, active layers)
Top view (emission facet)
T (°C)
Active layers
Bragg mirror
Substrate
90 mm
250 mm
T (°C)

8. Numerical circuit 180 nm technology (TIMA Grenoble)
Clock frequency 225 MHz
Lock-in at the repetition frequency of the test vectors (7.5 Hz)
Thermoreflectance
Resolution : 350 nm
80 mm
T(K)
Backside imaging ?

9. 2 Near Infrared thermoreflectance

10. Thermoreflectance with an InGaAs camera
Si Transparency region
4f < 40 Hz
InGaAs
CCD
White lamp
Microscope
Non coherent sources
eliminate interference in the substrate
Pow.1: f

11. Near Infrared back side imaging
DR/R
X50, 0.6N.A. objective
Resolution 2 mm (Diffraction limit : 1.7 mm)
Dissipated power : 500 mW

12. DR/R
Resolution difficult to assess (noisy image)
Average of FWHM : 650 nm
Effective N.A. : 1.55
Diffraction limit with a 0.42 N.A. objective: 2.4 mm

13. 3 Thermoreflectance and photoreflectance spectroscopy

14. Thermo-/photo- reflectance spectroscopy
Compact fibered spectrometer
+ focusing lens
R and vary sharply
due to interference
CCD
spectrometer
Spatial selectivity : a few mm
Spectral resolution : 1 nm typ.
Sensitivity : DR/R~ in 1 min
Filter
White
Lamp
P. Supply 2: 4F
Microscope
P. Supply 1: F
Circuit

15. Photoreflectance spectroscopy on passive materials
Amplitude DR/R
Measurement
l=615 nm
F=0.5 Hz
Heating
l=10.6 mm
SiO2 (glass)
F=1 Hz
CCD
spectrometer
Filter
White
Lamp
F=3Hz
P. Supply 2: 4F
Microscope
P. Supply 1: F
Modulated CO2 laser
F=7.5 Hz
Sample
1850 mm

16. Gold nanospheres in silica (preliminary results)
M. Rashidi, B. Palpant, INSP
x10-4
DR/R
SiO2 + gold nanospheres (≈ 4 nm)
Measurement
DT ≈ 3 K
t= 68 nm
Heating
l=10.6 mm
Si substrate
x10-3
DR/R
Model DT=50 K
Majid Rashidi, INSP

17. Conclusions 1 ) Visible thermoreflectance resolution ≈ 300 nm
precision of calibrated measurement ≈ 5%
2 ) NIR imaging with Solid Immersion Lenses
- Resolution : 650 nm at l=1.65 nm, effective N.A.: 1.55
- Resolution improvement :
use narrow band illumination
better contact SIL / substrate
3) Spectroscopy
Fast and sensitive DR/R~ in 1 min
Good spectral resolution (1 nm)
Performance spectrometer dependent
DR/R~ should be achievable in 1 min with a e- well depth.