Title: Design Limits for Thin Dielectric Film Capacitors
1Design Limits for Thin Dielectric Film
Capacitors Rensselaer Team Â
Prof. Eugene J. Rymaszewski , Prime
Investigator Prof. Toh-Ming Lu, Co-Investigator
(processing) Pushkar Jain (leveraged from
CPES) Jasbir Juneja Vinay Bhagwat Dr.
Matthew Nielsen (now GE CRD) Dr. Jin Young Kim
(now TI)
2Objectives
- Novel high performance decoupled power
distribution planes (high C, very low L) and
embedded discrete capacitors. - Achieve
- capacitance densities in several hundred nF/cm2
range, - effective inductances in pH range,
- breakdown voltages above 10-25 V, and
- leakage current densities below 1 ?A/cm2.
- Contain within acceptable limits the
electromagnetic interactions between the power
distribution planes and the signal connections
which traverse through these planes.
3Accomplishments
Empirically determined interdependency between er
and EBR. Derived breakdown voltage vs.
capacitance density (µF/cm2) for er of 3 to 3000
and films between 10 nm and 100 µm
thick. Measured effects of the film thickness on
I-V characteristics. Measured the role of Oxygen
concentration during sputtering. Designed and
used GHz characterization test vehicles.
4micro-roughness of the metal plate surfaces
Related consideration
5Empirical equation EBR20/ er0.5 From E
V/d where, E Electric field (MV/cm)
V Voltage (V) d Thickness
(cm) and Ce0 er A/d where, C Capacitance
(F) e0 8.85x10 -14 ( F/cm) A
Area of capacitor (cm2) Vmax 60 d0.5
1/(C/A)0.5, and Vmax 1.7 ?r0.5 1/(C/A)
These relationships delineate the design space
6Design space
Vmax 60 d0.5 1/(C/A)0.5
Vmax 1.7 ?r0.5 1/(C/A)
7Experimental data
8No thickness dependency of the dielectric constant
9Causes of the lower breakdown voltage/field E
BR lower than 20/er 0.5 Materials
micro-structure amorphous, crystalline,
columnar Materials defects, e.g. metal in
insulator (e.g. _at_ low Oxygen) Non-conformal
deposition and micro-roughness of the bottom
metal surface caused by an enhancement of the
metal to polymer bond Â
10The local breakdown with thin films
11Experimental data
12Columnarity occurance on films thicker than
approx. 1 1.5 µm
13I-V Characteristics of Tantalum oxide films
14Effect of oxygen concentration during sputtering
on er
Temperature dependency of er of Ta2O5 thin films
15Reduction of the power-distribution
inductance Several placements of a decoupling
capacitor in a close proximity (external) to
the IC chip embedded in the semiconductor body
of the chip embedded within wiring planes of the
chip interposed between the chip and its
packaging High-K thin film between power and
ground planes
16High (medium) K dielectric thin film is
sandwiched between power and ground
planes Signal lines travels through the thin
film increased capacitance to power/ground
planes may be offset by higher apertures
diameter, but larger apertures decrease the
value of decoupling capacitor
17Characterization vehicle
18 S21 with
different probe positions
19Frequency dependence of dielectric constant
20Current endeavors
- Effects, causes and control (if needed) of
columnarity - Interaction between the power distribution
planes and - the signal lines transiting through these planes
- Integration of these structures
- Lower manufacturing costs than those by
sputtering