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© 2011 by SYSTEM PLUS CONSULTING, all rights reserved. Bosch 3-Axis accelerometer BMA250 1
9 rue Alfred Kastler - BP 10748 - 44307 Nantes Cedex 3 - France
Phone : +33 (0) 240 180 916 - email : [email protected] - website : www.systemplus.fr
December 2011- Version 1
Written by: Maher SAHMIMI
DISCLAIMER : System Plus Consulting provides cost studies based on its knowledge of the manufacturing and selling prices of electronic components and systems. The given values are realistic
estimates which do not bind System Plus Consulting nor the manufacturers quoted in the report. System Plus Consulting is in no case responsible for the consequences related to the use which is
made of the contents of this report. The quoted trademarks are property of their owners.
© 2011 by SYSTEM PLUS CONSULTING, all rights reserved. Bosch 3-Axis accelerometer BMA250 2
Table of Contents
Glossary
1. Overview / Introduction……………………….…........…4
– Executive Summary
– Reverse Costing Methodology
2. Bosch Sensortec Company Profile…………....……...6
– Bosch Sensortec
– BMA250 Specifications & Block Diagram
3. Physical Analysis………………………………......…...12
– Synthesis of the Physical Analysis
– Physical Analysis Methodology
– Package Characteristics & Markings
– Package Opening & Bonding Number
– Device Structure
– ASIC – Dimensions
– ASIC – Markings & Bond Pads
– ASIC – Functions
– ASIC Synthesis
– MEMS Sensor – Dimensions and Marking
– MEMS Sensor – X-Axis SEM Views
– MEMS Sensor – Y-Axis SEM Views
– MEMS Sensor – Z-Axis SEM Views
– MEMS Sensor – Capacitances electrodes
– Component Cross-Section
– MEMS Cross-Section AA‘
– MEMS Cross-Section BB
– Physical Data Summary
– MEMS process characteristics
– Comparisons with Previous Generation
4. Manufacturing Process Flow…………………………..….49
– Global Overview
– ASIC Process Flow
– Description of the ASIC Wafer Fabrication Unit
– MEMS Process Flow
– Description of the MEMS Wafer Fabrication Unit
5. Cost Analysis……………………………………………..…..64
– Synthesis of the Cost Analysis
– Main Steps of Economic Analysis
– Yields Explanation
– Die per wafer & Probe Test
– ASIC Wafer Front-End Cost
– ASIC Die Cost
– MEMS Wafer Front-End Cost
– MEMS Front-End Cost per Process Steps
– MEMS Front-End : Equipment Cost per Family
– MEMS Front-End : Material Cost per Family
– MEMS Back-End 0 : Probe Test & dicing
– MEMS Die Cost
– Back-End 1 : Packaging, Final test, calibration
– BMA250 Component Cost (FE + BE 0 + BE 1)
– Yields Synthesis
6. Estimated Manufacturer Price Analysis ………………...87
– Supply Chain Analysis
– Manufacturers financial ratios
– Estimated Manufacturer Price
Conclusion ……………………………………………………....91
© 2011 by SYSTEM PLUS CONSULTING, all rights reserved. Bosch 3-Axis accelerometer BMA250 3
Synthesis of the Physical Analysis
ASIC
Cap
Sensor
Cap:
Substrate:
Process:
Glass Frit bonded on the sensor
Sensor:
Substrate:
Process :
Package:
Standard LGA-12 pin package
ASIC:
Substrate:
Process:
Glued on the CAP
Package
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Package X-ray Side view
Gold wire bonding nb
Total 18
ASIC&Package 8
MEMS&ASIC 10
ASIC
MEMS Cap
MEMS Sensor
PCB
Au wire bonding
ASIC&MEMS Au wire bonding
ASIC&Package
2 Metal Layers Via
Package X-ray Top view
Wire bonding
ASIC & Package
Via in the PCB substrate
Wire bonding
ASIC & MEMS
Package X-ray : Bondings number
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Package Opening SEM View
ASIC Pad SEM View
SAW Mark.
SAW Mark
Package Opening - SEM View
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ASIC Die Overview
ASIC – Memory
ROM Memory SEM view Memory Area SEM view
ROM
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Movable electrodes are attached to the proof mass
and form capacitors with fixed electrodes. When an
acceleration is applied, the capacitor value changes. The
signal is then evaluated by an ASIC.
The motion stop avoids the direct contact of the
electrodes at large accelerations.
MEMS Sensor – X-Axis SEM Views
X-Axis- SEM View
X-Axis- Tilt View
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Si wafer
• Thinning 300µm
• Pad oxide (Oxide1) deposit
Si wafer
• Buried Poly (Poly1) deposition
• Ion implantation
• Pattern & etch
Si wafer
• Sacrificial Oxide 1 (Oxide 2) deposit
• Pattern & etch
Si wafer
• Seed Layer (Poly 2) Deposition
• Ion implantation
• Pattern & Etch
MEMS Process Flow 1/4
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Sensor FE Cost per Process Steps (2/2)
Sensor Manufacturing Steps Cost (Simulated with MEMS CoSim+ Cost Simulation Tool)
Structural Layer : Deposition of Thick Polysilicon : Epi-Poly $ 23.26 15.62%
Structural Layer : Chemical Mechanical Planarization:CMP $ 11.72 7.87%
Structural Layer : Annealing $ 0.71 0.48%
Structural Layer : Wet Etching (BHF) Phospho Silicate Glass-PSG $ 0.67 0.45%
Structural Layer : LPCVD-Oxide (SiO2) $ 0.89 0.60%
Structural Layer : P-Ions Implantation $ 2.02 1.35%
Structural Layer : Annealing $ 1.44 0.96%
Structural Layer : Wet Etching (BHF) Oxide-SiO2 $ 3.45 2.32%
Metal layer : Deposition of PVD-Aluminum (Al) $ 8.90 5.97%
Metal layer : Lithography single Side $ 2.83 1.90%
Metal layer : Wet Etching Aluminun-Al $ 1.63 1.09%
Metal layer : PR Removal:Photoresist Ashing $ 0.51 0.34%
Mobile elements : Lithography single Side $ 2.83 1.90%
Mobile elements : High Aspect Ratio Etching-DRIE $ 18.65 12.52%
Mobile elements : PR Removal:Photoresist Ashing $ 0.51 0.34%
Mobile elements : HF_Vapor Etching Oxide-SiO2 $ 3.44 2.31%
Parametric Test $ 4.81 3.23%
Total 148.96
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MEMS Front-End : Equipment Cost per Family
MEMS Equipment Cost per Family
(Simulated with MEMS CoSim+ Cost
Simulation Tool)
• Cost of the equipment for Cap+sensor manufacturing.
• The main part of the equipment cost is due to the etching and
deposition steps with 57% (the 20µm epipoly and DRIE steps
explain this value).
Details of the equipment cost per step are given in the Excel Spreadsheet.
Etching
41%
Deposition17%
Lithography8%
Implantation4%
Testing3%
Measurement3%
CMP1%
Removal1%
Thermal Step4%
Cleaning2%
Bonding14%
Backgrinding
2%
MEMS Equipment Cost Breakdown per Family
Etching $ 32.59 40%
Deposition $ 13.48 17%
Lithography $ 6.48 8%
Implantation $ 3.13 4%
Testing $ 2.29 3%
Measurement $ 2.40 3%
CMP $ 1.16 1%
Removal $ 1.12 1%
Thermal Step $ 3.47 4%
Cleaning $ 1.47 2%
Bonding $ 11.44 14%
Backgrinding $ 1.45 2%
Total $ 80.49
Equipment FamilyEquipment
CostBreakdown
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• Reverse costing analysis represents the best cost/price evaluation given the publically
available data, completed with industry expert estimates.
• Given the hypothesis presented in this analysis the major sources of correction would
lead to a +/- 10% correction on the manufacturing cost (if all parameters are cumulated)
• IC +/- 8%
• MEMS +/- 5%
• Packaging +/- 10%
• Test +/- 20%
• These results are open for discussion. We can re-evaluate this circuit with your
information. Please contact us:
Conclusion