Etchants for use in micromachining of CMOS Microaccelerometers and microelectromechanical devices and method of making the same

In a method for fabricating a microelectromechanical (MEM) device, said MEM device being formed in or on at least one semiconductor substrate, including an integrated circuit formed therein by standard IC processing and including a microelectromechanical assembly, an improvement comprising:

• providing a substantially completed MEM device, said device being substantially completely fabricated except for a single etching step, said etching step defining a structural element within said microelectromechanical assembly from said at least one substrate to complete said device and to render said MEM device operable;
• and
• etching said MEM device with xenon difluoride in a gas phase to define said structural element from said substrate.

In a method for fabricating a microelectromechanical (MEM) device, said MEM device being formed in or on at least one semiconductor substrate, including an integrated circuit formed therein by standard IC processing and including a microelectromechanical assembly, an improvement comprising:

• providing a substantially completed MEM device, said device being substantially completely fabricated except for a single etching step, said etching step defining a structural element within said microelectromechanical assembly from said at least one substrate to complete said device and to render said MEM device operable;
• and
• etching said MEM device with an etchant selected from the group of xenon difluoride and an aqueous solution of tetramethyl ammonium hydroxide and silicic acid to define said structural element with respect to said substrate.

In a method for fabricating a microelectromechanical (MEM) device, said MEM device being formed in or on at least one semiconductor substrate, including an integrated circuit formed therein by standard IC processing and including a microelectromechanical assembly, an improvement comprising:

• providing a substantially completed MEM CMOS device, said device being substantially completely fabricated except for at least one etching step, said etching step defining a structural element within said microelectromechanical assembly from said at least one substrate to complete said device and to render said MEM device operable;
• and
• etching said MEM CMOS device with a noble gas fluoride to define said structural element with respect to said substrate.

In a method for mass fabrication of microelectromechanical devices, an improvement comprising:

• providing a multiplicity of devices each having portions which must be oriented to predetermined three dimensional positions in order assume a final configuration for each said device, selected portions of each said device having an electrically isolated structure for receiving and holding charge for at least a temporary period;
• and
• selectively disposing selected amounts of electric charge on said selected portions of each said device to generate mutually repulsive or attractive electrostatic forces between said selected portions to move said selected portions of each said device to said final configuration.

An improvement in a microelectromechanical (MEM) device having a substrate and a movable part separate from said substrate formed as part of said microelectromechanical (MEM) device, said improvement comprising a conductive and permanently deformable hinge coupling said substrate and said movable part to allow permanent spatial reconfiguration of said movable part with respect to said substrate.

A method for fabricating a microelectromechanical (MEM) device on or in at least one substrate by removing mechanical constraints disposed between and connecting at least two components of said microelectromechanical (MEM) device after said at least two components have been formed, said mechanical restraints being removed by vapor phase etching said microelectromechanical (MEM) device in a noble gas fluoride.