Micromachining is a key fabrication technology for microscale structures, devices, and MEMS.. Bulk micromamicroma-chining of silicon uses wet and dry etching techniques in conjunction wi
Trang 1that the spherical-conical micromotors develop higher electromagnetic torque compared with the con-ventional design In addition, improved cooling, reduced undesirable torques components, as well as increased ruggedness and robustness contribute to the viability of the proposed solution Thus, using the classifier paradigm, novel microdevices with superior performance can be devised
14.3 MEMS Fabrication
Microelectromechanics, which integrates micromechanics and microelectronics, requires affordable, low-cost, high-yield fabrication technologies which allow one to fabricate 3-D microscale structures and devices Micromachining is a key fabrication technology for microscale structures, devices, and MEMS
Microelectromechanical systems fabrication technologies fall into three broad categories: bulk machining, surface machining, and LIGA (LIGA-like) techniques [1–3]
Bulk Micromachining
Bulk and surface micromachining are based on the modified CMOS and specifically designed microma-chining processes Bulk micromamicroma-chining of silicon uses wet and dry etching techniques in conjunction with etch masks and etch-stop-layers to develop microstructures from the silicon substrate Microstruc-tures are fabricated by etching areas of the silicon substrate to release the desired 3-D microstrucMicrostruc-tures
are widely used in bulk micromachining The microstructures are formed by etching away the bulk of the silicon wafer to fabricate the desired 3-D structures Bulk machining with its crystallographic and dopant-dependent etch processes, when combined with wafer-to-wafer bonding, produces complex 3-D microstructures with the desired geometry Through bulk micromachining, one fabricates microstruc-tures by etching deeply into the silicon wafer There are several ways to etch the silicon wafer The
wafer) are fabricated In contrast, the isotropic etching etches all directions in the silicon wafer at same (or close) rate, and, therefore, hemisphere and cylinder structures can be made Deep reactive ion etching uses plasma to etch straight walled structures (cubes, rectangular, triangular, etc.)
Surface Micromachining
Surface micromachining has become the major fabrication technology in recent years because complex 3-D microscale structures and devices can be fabricated Surface micromachining with single-crystal silicon, polysilicon, silicon nitride, silicon oxide, and silicon dioxide (as structural and sacrificial materials which deposited and etched) is widely used to fabricate microscale structures and devices on the surface
of a silicon wafer This affordable low-cost high-yield technology is integrated with IC fabrication processes guaranteeing the needed microstructures-IC fabrication compatibility The techniques for depositing and patterning thin films are used to produce complex microstructures and microdevices on the surface of silicon wafers (surface silicon micromachining) or on the surface of other substrates Surface micromachining technology allows one to fabricate the structure as layers of thin films This technology guarantees the fabrication of 3-D microdevices with high accuracy, and the surface micromachining can
be called a thin film process Each thin film is usually limited to thickness up to 5 µm, which leads to fabrication of high-performance planar-type microscale structures and devices The advantage of surface micromachining is the use of standard CMOS fabrication processes and facilities, as well as compliance with ICs Therefore, this technology is widely used to manufacture microscale actuators and sensors (microdevices)
Surface micromachining is based on the application of sacrificial (temporary) layers that are used to maintain subsequent layers and are removed to reveal (release) fabricated (released or suspended) micro-structures This technology was first demonstrated for ICs and applied to fabricate microstructures in the 80s On the surface of a silicon wafer, thin layers of structural and sacrificial materials are deposited
©2002 CRC Press LLC
Trang 2that the spherical-conical micromotors develop higher electromagnetic torque compared with the con-ventional design In addition, improved cooling, reduced undesirable torques components, as well as increased ruggedness and robustness contribute to the viability of the proposed solution Thus, using the classifier paradigm, novel microdevices with superior performance can be devised
14.3 MEMS Fabrication
Microelectromechanics, which integrates micromechanics and microelectronics, requires affordable, low-cost, high-yield fabrication technologies which allow one to fabricate 3-D microscale structures and devices Micromachining is a key fabrication technology for microscale structures, devices, and MEMS
Microelectromechanical systems fabrication technologies fall into three broad categories: bulk machining, surface machining, and LIGA (LIGA-like) techniques [1–3]
Bulk Micromachining
Bulk and surface micromachining are based on the modified CMOS and specifically designed microma-chining processes Bulk micromamicroma-chining of silicon uses wet and dry etching techniques in conjunction with etch masks and etch-stop-layers to develop microstructures from the silicon substrate Microstruc-tures are fabricated by etching areas of the silicon substrate to release the desired 3-D microstrucMicrostruc-tures
are widely used in bulk micromachining The microstructures are formed by etching away the bulk of the silicon wafer to fabricate the desired 3-D structures Bulk machining with its crystallographic and dopant-dependent etch processes, when combined with wafer-to-wafer bonding, produces complex 3-D microstructures with the desired geometry Through bulk micromachining, one fabricates microstruc-tures by etching deeply into the silicon wafer There are several ways to etch the silicon wafer The
wafer) are fabricated In contrast, the isotropic etching etches all directions in the silicon wafer at same (or close) rate, and, therefore, hemisphere and cylinder structures can be made Deep reactive ion etching uses plasma to etch straight walled structures (cubes, rectangular, triangular, etc.)
Surface Micromachining
Surface micromachining has become the major fabrication technology in recent years because complex 3-D microscale structures and devices can be fabricated Surface micromachining with single-crystal silicon, polysilicon, silicon nitride, silicon oxide, and silicon dioxide (as structural and sacrificial materials which deposited and etched) is widely used to fabricate microscale structures and devices on the surface
of a silicon wafer This affordable low-cost high-yield technology is integrated with IC fabrication processes guaranteeing the needed microstructures-IC fabrication compatibility The techniques for depositing and patterning thin films are used to produce complex microstructures and microdevices on the surface of silicon wafers (surface silicon micromachining) or on the surface of other substrates Surface micromachining technology allows one to fabricate the structure as layers of thin films This technology guarantees the fabrication of 3-D microdevices with high accuracy, and the surface micromachining can
be called a thin film process Each thin film is usually limited to thickness up to 5 µm, which leads to fabrication of high-performance planar-type microscale structures and devices The advantage of surface micromachining is the use of standard CMOS fabrication processes and facilities, as well as compliance with ICs Therefore, this technology is widely used to manufacture microscale actuators and sensors (microdevices)
Surface micromachining is based on the application of sacrificial (temporary) layers that are used to maintain subsequent layers and are removed to reveal (release) fabricated (released or suspended) micro-structures This technology was first demonstrated for ICs and applied to fabricate microstructures in the 80s On the surface of a silicon wafer, thin layers of structural and sacrificial materials are deposited
©2002 CRC Press LLC