1. Results on Recent pCVD Diamond Samples
Maurizio Vannoni INOA Stefano Lagomarsino INFN and University of Florence
CERN RD42 meeting March 31- April

2. In the following slides, I will show how the micro-interferometric tecnique is relevant:
In the framework of RAPSODIA experiment (Radiation Active Pixel Silicon On DIAmond), for discriminate suitable surfaces for wafer-bonding
In the characterization of polycristalline CVD Diamond, to study the morphologic characteristic of substrate and growth sides of diamond films.

3. (Relatively )High Pressure High Temperature Bonding
RAPSODIA (Radiation Active Pixel Silicon on DIAmond) Gr. V national INFN experiment started in 2007
Program: development of a technique of wafer-bonding of silicon-on-diamond (SOD)
Motivations: diamond as insulator in a silicon-on-insulator structure with superior thermal properties, diamond acting as handle wafer and possibly as rad-hard detector
(Relatively )High Pressure High Temperature Bonding
Two different approaches
Mastering SOD technology is the aim of several research groups in US and Europe, now.
Laser Enhanced Bonding

4. High Pressure High Temperature Bonding Laser Enhanced Bonding
For both these approaches, it is crucial to obtain a contact as intimate as possible between diamond and silicon surfaces
Mechanical pressure up to 300 atm, at 950C, gives fairly good results only on a limited portion of the interfacial surface*.
*G.N. Yushin et al. Wafer bonding of highly oriented diamond to silicon, Diamond & Related Materials 13 (2004) 1816–1821

5. RAPSODIA plans an increment of the pressure of a least a factor 3 (about 1000 atm), but the question is
- Which is the minimum pressure necessary to obtain, say, 90% of adherence within fractions of nm?

6. Constans relative to Silicon Surface factor of Diamond
We found that a fourier analysis of diamond surface, permit to stand a simple relation between Scontact/Stot and the pressure P. P
Pressure P is related to the 2D-fourier transform h of the surfaces in the following way:
Constans relative to Silicon
Surface factor of Diamond
We performed this analysis on a batch of 3 samples purchased by Element 6 (obtained through RD42 coll.)

7. Surface factor of Diamond
=0.49e-3 Side A
=1.31 e-3 Side B
Pressure P=490 atm
Pressure P=1300 atm

8. Polycristalline nature of the material is clearly recognizable by images, as well as the difference in cristal size between the two sides of each sample.

9. The size of the cristals and their shape are also recognizable under the metallizations.
Thus, it could be possible to match this images with those obtained with other imaging tecniques, like IBIC

10. Samples label: EL0100-0100-0500 CERN 1006107-2
At the end: a couple slides to show results on 2 samples by Element-6, metallized in Bologna (IMM-CNR)* with a recipe from Ohio State University.
Samples label: EL CERN
- Cleaning with Oxygen plasma
- Ti-sputtering 50 nm
- Au-sputtering 400 nm
- Annealing in N2: 400°C for 15 min, temperature rise time 40 min and fall time 130 min.
*Credits: Ivan Elmi, Giulio Pizzochero, Andrea Scorzoni,
Institute of Microelectronics and Microsystems, IMM –CNR Bologna Italy

11. SAMPLE: EL0100-0100-0500 CERN 1006107-2 IMM #2
CV characteristics shows constant capacitance within 0.25% in the range 1-100kHz , from -500 V to +500V.
The IV characteristic shows currents below 1pA from
-500 to 500V and a very symmetric but moderately non-ohmic IV profile

12. CCD pulse height spectrum
EL CERN IMM #1 (PUMPED)

13. S curve exhibits no pumping or hysteresis effects (or are they within experimental errors)
CCD of about 220m at E=1V/m

14. Results on Recent pCVD Diamond Samples
Maurizio Vannoni INOA Stefano Lagomarsino INFN and University of Florence
Thank you for listening!
CERN RD42 meeting March 31- April