Freescale Semiconductor MMA6222AEG ±20/20g Dual-Axis Medium-g Micromachined HARMEMS Accelerometer MEMS Process Review For comments, questions, or more information about this report, or for any additional technical needs concerning semiconductor and electronics technology, please call Sales at Chipworks. 3685 Richmond Road, Suite 500, Ottawa, ON K2H 5B7, Canada Tel: 613.829.0414 Fax: 613.829.0515 www.chipworks.com
MEMS Process Review Some of the information is this report may be covered by patents, mask and/or copyright protection. This report should not be taken as an inducement to infringe on these rights. 2009 Chipworks Inc. This report is provided exclusively for the use of the purchasing organization. It can be freely copied and distributed within the purchasing organization, conditional upon the accompanying Chipworks accreditation remaining attached. Distribution of the entire report outside of the purchasing organization is strictly forbidden. The use of portions of the document for the support of the purchasing organization s corporate interest (e.g., licensing or marketing activities) is permitted, as defined by the fair use provisions of the copyright act. Accreditation to Chipworks must be attached to any portion of the reproduced information. MPR-0904-801 13523JMRK Revision 1.0 Published: August 14, 2009
MEMS Process Review Table of Contents 1 Overview 1.1 List of Figures 1.2 List of Tables 1.3 Company Profile 1.4 Introduction 1.5 Device Summary 1.6 Process Summary 2 Device Overview 2.1 Package and Die Overview 2.2 MEMS Die Features and Internal Vapor Analysis 2.3 ASIC Die and Die Features 3 Package Cross Section 3.1 Overview 3.2 MEMS Die, Cap, and ASIC Die in a Package 3.3 MEMS and ASIC Die and Package Lead Bond Pads 4 ASIC Die Process Overview 4.1 Overview 4.2 Dielectrics, Metals, and Contacts 4.3 Transistors, Poly-Poly Capacitor, STI, and DTI 5 MEMS Die and Silicon Cap Process Analysis 5.1 Overview 5.2 MEMS Substrate and Silicon Cap 5.3 Bond Pads 5.4 Poly Interconnect, SOI, and Dielectrics 5.5 Vias and Contacts 6 MEMS Architectural Analysis 6.1 Architectural Overview 6.2 SOI Proof Mass and Fixed Beams 6.3 Spring, Anchor, and Interconnects 6.4 Motion Stop and Air Bridges
MEMS Process Review 7 Critical Dimensions 7.1 Device Summary and Major Feature Dimensions 7.2 Package Cross Section, SEM-EDS Summary, and Critical Dimensions 7.3 MEMS Internal Vapor Analysis 7.4 MEMS Accelerometer Critical Dimensions 7.5 ASIC Critical Dimensions 8 References 9 Statement of Measurement Uncertainty and Scope Variation About Chipworks
Overview 1-1 1 Overview 1.1 List of Figures 2 Device Overview 2.1.1 Package Top 2.1.2 Package Bottom 2.1.3 MMA6222AEG Plan-View Package X-Ray 2.1.4 MMA6222AEG End-View X-Ray 2.1.5 MMA6222AEG Side-View X-Ray 2.1.6 MMA6222AEG During Deprocessing 2.2.1 Top Half of MEMS Accelerometer Plan View 2.2.2 Bottom Half of MEMS Accelerometer Plan View 2.2.3 MEMS Accelerometer Tilt View 2.2.4 Corner of MEMS Accelerometer Plan View 2.2.5 Corner of MEMS Accelerometer Tilt View 2.2.6 Wires Connecting MEMS Accelerometer to ASIC Die 2.2.7 Bond Pads of MEMS Accelerometer Plan View 2.2.8 Wedge Bonds on MEMS Accelerometer Tilt View 2.2.9 MEMS Die Photograph 2.2.10 MEMS Die Analysis Sites 2.2.11 Underside of Si Cap 2.2.12 MEMS Die Markings A 2.2.13 MEMS Die Markings B 2.3.1 ASIC Die Photograph 2.3.2 ASIC Die Markings 2.3.3 ASIC Die Corner 2.3.4 ASIC Ball Bond Pads 2.3.5 ASIC Wedge Bond Pads 3 Package Cross Section 3.1.1 Package Cross Section Overview 3.2.1 MEMS Assembly and Package Overview 3.2.2 Left Edge of MEMS Assembly 3.2.3 Right Edge of MEMS Assembly 3.2.4 MEMS Cap Plating 3.2.5 Detail of MEMS Lid and Lead Glass 3.2.6 ASIC Die to Package Lead Attach 3.3.1 MEMS Die and Cap Wedge Bonds 3.3.2 ASIC Die Wedge Bond 3.3.3 ASIC Die Ball Bond 3.3.4 Package Lead Stitch Bond
Overview 1-2 4 ASIC Die Process Overview 4.2.1 Die Edge 4.2.2 Die Seal 4.2.3 Minimum Pitch Metal 3 4.2.4 Minimum Pitch Metal 1 4.3.1 MOS Transistor Oxide Etch 4.3.2 Minimum Gate Length PMOS Transistor 4.3.3 Minimum Gate Length NMOS Transistor 4.3.4 Poly-Poly Capacitor (Poly 2 Poly 1) 4.3.5 NPN Bipolar Transistor and Minimum Width DTI 4.3.6 DTI Top 4.3.7 DTI Bottom 5 MEMS Die and Silicon Cap Process Analysis 5.2.1 MEMS Cap and Accelerometer Die Optical 5.2.2 MEMS Cap and Accelerometer Die SEM 5.2.3 SCM of MEMS Cap and MEMS Die 5.2.4 MEMS Die Edge 5.2.5 MEMS Die Edge in Detail 5.2.6 Left Edge of Si Cap Cavity 5.2.7 Right Edge of Si Cap Cavity 5.3.1 MEMS Die Wedge Bond Optical 5.3.2 MEMS Die Wedge Bond SEM 5.3.3 Aluminum Bond Pad in Detail 5.4.1 General MEMS Structure Near Left Edge of MEMS Cavity Optical 5.4.2 General MEMS Structure Near Right Edge of MEMS Cavity Optical 5.4.3 General MEMS Structure Near Left Edge of MEMS Cavity SEM 5.4.4 General MEMS Structure Near Right Edge of MEMS Cavity SEM 5.4.5 General MEMS Structure Near the Center of MEMS Die Oxide Etch 5.4.6 SCM of MEMS Structure Near Left Edge of MEMS Cavity 5.4.7 Accelerometer SOI Beam Detail Top 5.4.8 Accelerometer SOI Beam Detail Bottom 5.4.9 Minimum Pitch SOI Top 5.4.10 Minimum Pitch SOI Bottom 5.4.11 Poly Line 5.4.12 Edge of a Poly Line 5.4.13 Field Oxide and Bird s Beak 5.5.1 Minimum Pitch Poly Via 5.5.2 Poly Contact 5.5.3 Poly Contact Bottom 5.5.4 Poly Contact Top 5.5.5 SCM of Poly Contact
Overview 1-3 6 MEMS Architectural Analysis 6.1.1 Accelerometer Plan View 6.1.2 Accelerometer Planes of Cross Section 6.1.3 Accelerometer Architecture Overview 6.2.1 MEMS Accelerometer Tilt View 6.2.2 Top Left Corner of X-Direction Accelerometer Optical Plan View 6.2.3 Bottom Left Corner of X-Direction Accelerometer Optical Plan View 6.2.4 Corner of X-Direction Accelerometer (Type A Fixed Plate) SEM Plan View 6.2.5 Type B Fixed Plate Near Center of Accelerometer Plan View 6.2.6 Corner of Proof Mass in Detail 6.2.7 Release Slot Holes 6.3.1 Spring and Anchor 6.4.1 Motion Stops Tilt View 6.4.2 Motion Stops Plan View 6.4.3 Substrate Contact Tilt View 6.4.4 Poly Air Bridges Tilt View
Overview 1-4 1.2 List of Tables 1 Overview 1.4.1 Device Identification 1.5.1 MMA6222AEG Device Summary 1.5.2 MEMS Accelerometer Die Summary 1.5.3 ASIC Die Summary 1.6.1 MEMS Accelerometer Die Process Summary 1.6.2 ASIC Die Process Summary 2 Device Overview 2.2.1 MEMS Internal Vapor Analysis 2.2.2 Package and MEMS Die Critical Dimensions 2.3.1 ASIC Die Critical Dimensions 3 Package Cross Section 3.1.1 Package Cross Section SEM-EDS Analysis Summary 3.1.2 Package Critical Vertical Dimensions 4 ASIC Die Process Overview 4.1.1 ASIC Die Observed Vertical Critical Dimensions 4.1.2 ASIC Die Observed Horizontal Critical Dimensions 5 MEMS Die and Silicon Cap Process Analysis 5.1.1 MEMS Accelerometer Vertical Critical Dimensions 5.1.2 MEMS Accelerometer Horizontal Critical Dimensions 6 MEMS Architectural Analysis 6.1.1 MEMS Accelerometer Critical Dimensions 7 Critical Dimensions 7.1.1 MMA6222AEG Device Summary 7.1.2 MEMS Accelerometer Die Summary 7.1.3 ASIC Die Summary 7.2.1 Package Cross Section SEM-EDS Analysis Summary 7.2.2 Package Critical Dimensions 7.3.1 MEMS Internal Vapor Analysis 7.4.1 MEMS Accelerometer Vertical Critical Dimensions 7.4.2 MEMS Accelerometer Horizontal Critical Dimensions 7.4.3 MEMS Accelerometer Critical Dimensions 7.5.1 ASIC Die Observed Vertical Critical Dimensions 7.5.2 ASIC Die Observed Horizontal Critical Dimensions