Results on Recent pCVD Diamond
Samples
Maurizio Vannoni
INOA
Stefano Lagomarsino
INFN and University of Florence
CERN RD42 meeting March 31- April 1 2008
In the following slides, I will show how the microinterferometric 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.
(Radiation Active Pixel Silicon on DIAmond)
Gr. V national INFN experiment started in 2007
RAPSODIA
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
Two different approaches
Mastering SOD
technology is the aim of
several research groups
in US and Europe, now.
(Relatively )High Pressure
High Temperature
Bonding
Laser Enhanced Bonding
•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
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?
RAPSODIA
We found that a fourier analysis of diamond surface,
permit to stand a simple relation between Scontact/Stot and
the pressure P.
 P 
S contact

 2  erf 

Stot
P
2
 

P
P
Pressure P is related to the 2D-fourier transform h of the
surfaces in the following way:
 1
P  J c J s  2 
L L
 x y
  d d 
2

  h , 
2
1/ 2
2




Constans relative Surface factor of Diamond
to Silicon
We performed this analysis on a batch of 3 samples
purchased by Element 6 (obtained through RD42 coll.)
Surface factor of Diamond
 1
2 
L L
 x y
  d d 
2

  h , 
2
1/ 2
2




Pressure PSide
=0.49e-3
A atm
=490
=1.31
e-3 PSide
B
Pressure
=1300 atm
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.
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
At the end: a couple slides to show results on 2
samples by Element-6, metallized in Bologna (IMMCNR)* with a recipe from Ohio State University.
Samples label: EL0100-0100-0500 CERN 1006107-2
- 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
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 nonohmic IV profile
0.6
0.4
I (pA)
0.2
0.0
-0.2
-0.4
-0.6
-600
-400
-200
0
V (V)
200
400
600
CCD pulse height spectrum
EL0100-0100-0500 CERN 1006107-2 IMM #1 (PUMPED)
400
350
Pulse Height Spectrum
Fit
Deconvoluted Landau
300
Counts
250
200
150
100
50
0
0
5000
10000
15000
electrons
20000
25000
mean electron value
EL0100-0100-0500 CERN 1006107-2
IMM-#1
unpumped
pumped
8000
6000
4000
2000
0
-2000
-4000
-6000
-8000
-300-200-100 0 100 200 300 400 500 600
Bias Voltage
S curve exhibits no pumping or hysteresis effects (or are
they within experimental errors)
CCD of about 220m at E=1V/m
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 1 2008