DEN-K3Q5J-06

CONFIDENTIAL
関係者外秘
Date
Report
1/20
5-May-2016
DENSO Driving Assist & Safety Eng. Div.3
Driving Assist & Safety Quality Assurance Div.
To
HONDA NORTH AMERICA, INC.
Market Quality Department.
cc
Title
Filed claim investigation result for Airbag sensor (G2)
We report the field claim investigation result for Airbag sensor.
Part Name : SENSOR ASSY, SATELLITE SAFING (rep)
Part Number : 77975T6A J110M2 (rep)
This information is the exclusive property of DENSO CORPORATION. Without their consent, it may not be reproduced or given to third parties.
CONFIDENTIAL
関係者外秘
6/20
■Interlayer film delamination process
Process
Initial
Interlayer film condition
Mold
package
Description
1st metal layer
Interlayer oxide
P
Via
film (BPTEOS)
≒7500Å
Polysilicon
B
Interlayer oxide film contains P(Phosphorus) and
B(Boron).
Nitride film
・・・P and B protect the impurity ion in orde to
(PEN)
acquire the transistor characteristics.
≒500Å
Silicon substrate
Absorp
moisture
↓
Delamination
occurs
Tensile stress
Delamination between
BPTEOS and PEN
H2O
Tensile stress
Via
disconnection
occurs
Via disconnection
* Occurred because of
loading of G sensor chip,
etc.
When P concentration between BPTEOS and PEN
increased, the interfacial bond strength decreased,
and interlayer film was delaminated.
 Mechanism of bond strength
decrease on the next page.
Via was disconnected
because of tensile stress.
Delamination/disconnection
occurred at chip edge with
large internal stress.
H2O
This information is the exclusive property of DENSO CORPORATION. Without their consent, it may not be reproduced or given to third parties.
CONFIDENTIAL
関係者外秘
■Mechanism of bond strength decrease
Before moisture absorption
Molecular structure model
P2O5+3H2O → 2H3PO4
Phosphorus oxide Water
Phosphoric acid
After moisture absorption
BPTEOS film
Remarks
7/20
Phosphoric acid (H3PO4)
Interlayer
oxide film
（BPTEOS）
Interface
PEN film
Nitride film
（PEN）
- Si-O generate chemical bond strength to bond between P 2O5 and SiN.
(
)
* Some of O-OH in oxide film contributes as hydrogen bond. (
)
However, when P concentration is normal, SiO/SiN bond is dominant.
- Because of moisture, Si-O bond between P2O5 and SiN and hydrogen
bond are broken and the bond strength decreases. [Phosphoric acid
(H3PO4) is generated.]
When P concentration is normal, SiO/SiN bond is dominant, so the
bond strength decrease because of P2O5 moisture absorption has no
influence.
・in case of normal P concentration ⇒ P area is small ⇒ bond strength > Tensile stress ⇒ No delamination
・in case of rich P concentration ⇒ P area is wide ⇒ bond strength < Tensile stress ⇒ Delamination
P concentration affects the interfacial bond strength.
This information is the exclusive property of DENSO CORPORATION. Without their consent, it may not be reproduced or given to third parties.
5. Cause and countermeasure
■BPTEOS deposition device overview
CONFIDENTIAL
関係者外秘
8/20
* Machine below: FF09 (A, B, C, D) and FF10 (A, B, C, D)
② Oxygen gas
① Carrier gas
LFM * Liquid Flow Meter
Gas injection setting profile
TEPO flow volume
[mg/min]
* TEPO: Tri Ethyl Phosphate
TEOS: Tetra Ethyl Ortho Silicon
TEB : Tri Ethyl Borate
Flow volume overshoot
of stabilization
TEPO flow
volume
setting value
Time [sec]
Stabilization time
(Normal: 3sec)
①
Oxygen gas injection start
(deposition start)
②
Supply P by TEPO.
Confirmed that the process change of TEPO flow setting was happened.  Next page
This information is the exclusive property of DENSO CORPORATION. Without their consent, it may not be reproduced or given to third parties.
CONFIDENTIAL
関係者外秘
9/20
■Cause and countermeasure

Cause
Countermeasure (1)
- Machine error occurred because of TEPO flow volume variation.
Maintenance engineer changed the flow volume profile in order to control
the variation.
(Changed to an overshoot waveform to make the flow volume stable early.)
* At this moment, no knowledge that overshoot causes local concentration increase.
- Changed the flow volume profile not to overshoot.
(’14/12/17~)


TEPO flow
 At the time of deposition start, P concentration in chamber (shadowed
volume
area below) increased, and P concentration of interface between BPTEOS Setting value
and PEN films (soon after deposition start) increased.
SIMS value [wt%] TEPO flow volume

Stayed in chamber
until deposition start.

3sec
3sec
Time [sec]
Stabilization time
(3sec)
Deposition start
(Oxygen gas
injection)
Stabilization time
(3sec)
Deposition start
Local P
concentration
increase
Depth [nm]
Changed the flow volume profile to limit the peak of P concentration of interface between
BPTEOS and PEN films.
This information is the exclusive property of DENSO CORPORATION. Without their consent, it may not be reproduced or given to third parties.
CONFIDENTIAL
関係者外秘
10/20
Countermeasure (2)
Perform 100% monitoring of peak ratio for TEPO flow volume setting value in flow volume profile. (Sept. 1, 2015 ~)
Control item: TEPO flow volume setting value x Peak ratio
Control interval: 100% monitoring
Control value: 1.2 or less
* In the case of over 1.2 --- Machine stops. (Scrap the product.)
After adjusting the machine, check with SIMS result, and then flow.

Actual measured value
(Peak)
TEPO flow volume
setting value
* The above is the waveform of ratio ≒1.5. (Created intentionally.)
Perform 100% monitoring to see that flow volume profile is not overshoot.
This information is the exclusive property of DENSO CORPORATION. Without their consent, it may not be reproduced or given to third parties.
CONFIDENTIAL
関係者外秘

Cause
11/20
* SIMS --- Secondary Ion Mass Spectroscopy
Countermeasure
Process control width: 6.6 ~ 6.9wt% (Product spec: 6.4 ~ 7.2wt%)

7.2
6.9
6.6
- Introduce SIMS to control local P concentration. (‘14/12/17～)
(Continue concentration control by X-ray fluorescence.)
Control item: P concentration peak
Control value: MAX 9.2%
Control interval: 2/week or after every maintenance
* Chamber A: 1/D (under special control)
Measuring position: Center of wafer (Set as a result of investigation of
distribution in wafer surface)
P concentration [wt%]
- P concetration has been controlled by X-ray fluorescence. In this
method, only average value of P concentration in deposition direction can
be obtained, and local P concentration increase cannot be detected.
* No knowledge that increase of local P concentration causes
delamination.
SIMS waveform
Peak detected
6.4
Target lot period: ‘14/11/15 ~ ’14/12/13
Depth
 During the target lot period, P concentration (average value) increase
was not detected.
* Correlation between P concentration (average) by X-ray fluorescence and
P concentration (local) by SIMS is weak.
Introduced SIMS control for workmanship control of P concentration peak value.
This information is the exclusive property of DENSO CORPORATION. Without their consent, it may not be reproduced or given to third parties.