© 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 : info@systemplus.fr - 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