IRPS2008 Gaddi Haase P5 Dp2

AN ALTERNATIVE MODEL FOR INTERCONNECT LOW-K DIELECTRIC LIFETIME DEPENDENCE ON VOLTAGE Gaddi S. Haase Texas Instruments Dallas, TX, USA

Purpose ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Outline ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Low-k dielectric breakdown tests ,[object Object],[object Object],[object Object],[object Object],Stress time (s) Leakage (log scale)

Current decrease: Slow trap-charging? ,[object Object],[object Object],[object Object],Stress voltage time

The dielectric degradation process ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Top-down view Cu lines

The dielectric degradation process ,[object Object],[object Object],[object Object],The rising part of the I-t curve depends on the nature of the percolation paths that open between the electrodes. Actual stress: E=~4.1–4.4 MV/cm (Lower spacing required a slightly higher field) Drawn spacing (on the same wafer): 125nm 105nm 85nm 70nm 10 -4 10 -5 10 -6 10 -7 10 -1 10 10 3 10 5

[object Object],[object Object],Trap generation during stress Relaxation-current after stress interruption (pA) 4 3 2 1 0

Trap generation during stress ,[object Object],[object Object],Time Voltage -30V stress, 120s Min. No min. 10 -8 10 -8 10 -7 I x dt (Arb. Units)

Stress-induced leakage ,[object Object],[object Object],Drawn line-spacing: 125nm

Model: Trap generation ,[object Object],[object Object],[object Object],[object Object],[object Object],The rate of trap generation Electron flux Average distance between traps Drift between collisions with traps E a is the activation energy for a new trap formation

Model: Charge and Field The total electron density (trapped and mobile) The continuity eq . Poisson eq . Electron flux Field The mobile electron-density due to thermal excitation out of the traps: When the traps are full

Model: Leakage Electron flux A portion of the trapped electrons can tunnel between traps at high field and high trap density, which leads to breakdown: At the cathode, the available electron density is controlled by FN tunneling and thermal injection into the dielectric: Diffusion Coef. Median drift velocity is the width of a trapezoidal barrier

Model: 1D numerical solution ,[object Object],Line 1 Line 2 Side View Top View ,[object Object],[object Object],[object Object],Line 1 Line 2 ?

Model: 1D numerical solution 6.0 5.5 5.0 4.5 4.0 3.5 MV/cm 5.5 MV/cm 4.0 MV/cm ,[object Object],[object Object],[object Object],[object Object]

Model: 1D numerical solution The function does not describe the degradation process, but it is a safe/conservative and easy model to use for setting a lower limit to dielectric failure time vs. Field. ,[object Object],[object Object],[object Object],[object Object],New model 1D numerical sol.

Model: 1D numerical solution The parameters used to fit the model to the observed data are physical: ,[object Object],[object Object],=E a,App =

Model Summary ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Conclusions ,[object Object],[object Object],[object Object],[object Object]

IRPS2008 Gaddi Haase P5 Dp2

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Viewers also liked

Viewers also liked (7)

Similar to IRPS2008 Gaddi Haase P5 Dp2

Similar to IRPS2008 Gaddi Haase P5 Dp2 (20)

Recently uploaded

Recently uploaded (20)

IRPS2008 Gaddi Haase P5 Dp2

Editor's Notes