Micromechanical elements and methods for their fabrication

A method for making a microminiature pin joint with two members relatively movable to each other, comprising the steps of:

• (a) providing a first sacrificial coating over a substrate having openings therethrough to expose a portion of the substrate,
• (b) depositing a first structural layer over said first sacrificial coating and the exposed portion of the substrate, with openings therethrough to expose a second portion of the substrate,
• (c) providing a second sacrificial coating over said second exposed portion of the substrate and said first structural layer, with openings through both the first and second sacrificial layers to expose a third portion of the substrate,
• (d) adding a second structural layer thereover and defining it, and
• (e) etching the first and second sacrificial layers to remove them completely so that the two polysilicon layers become movable relative to each other.

A method for making a microminiature device with two members relatively movable to each other, comprising the steps of:

• (a) cleaning thoroughly and preparing a substrate wafer,
• (b) providing a first sacrificial layer thereon, said layer having a high etching rate in a selected etchant,
• (c) providing openings through said first sacrificial layer to expose a portion of the substrate,
• (d) depositing over said first sacrificial layer and the exposed portion of the substrate a first structural layer,
• (e) defining a selected area of said first structural layer and providing openings through that area of said structural layer and said first sacrificial layer to expose a second portion of said substrate,
• (f) coating a second sacrificial layer over said second exposed portion of said substrate and the edges of the openings leading thereto and said first structural layer,
• (g) providing openings through both said first and second sacrificial layers to expose a third portion of said substrate,
• (h) adding a second structural coating to form a second layer thereover and defining it, and
• (i) etching the first and second sacrificial layers to remove them completely so that said first and second structural layers become moveable relative to each other.

A method for making a microminiature pin joint with two members relatively movable to each other, comprising the steps of:

• (a) cleaning thoroughly and preparing a substrate wafer,
• (b) providing a first sacrificial layer thereon, said layer having a high etching rate in a selected etchant,
• (c) providing openings through said first sacrificial layer to expose a portion of the substrate,
• (d) depositing over said first sacrificial layer and the exposed portion of the substrate a first structural layer,
• (e) defining a selected area of said first structural layer and providing openings through that area of said structural layer and said first sacrificial layer to expose a second portion of said substrate,
• (f) coating a second sacrificial layer over said second exposed portion of said substrate and the edges of the openings leading thereto and said first structural layer,
• (g) providing openings through both said first and second sacrificial layers to expose a third portion of said substrate,
• (h) adding a second structural coating to form a second layer thereover and defining it, and
• (i) etching the first and second sacrificial layers to remove them completely so that said first and second structural layers become movable relative to each other.

A method for making a microminiature device with at least two members relatively movable to each other, comprising the steps of:

• (a) cleaning thoroughly and preparing a silicon substrate wafer,
• (b) providing a first layer of an oxide thereon, said oxide having a high etching rate in a selected etching acid,
• (c) providing openings through said first oxide layer to expose a portion of said substrate,
• (d) depositing over said first oxide layer and the exposed portion of said substrate a first layer of polysilicon,
• (e) defining a selected area of said first layer of polysilicon and providing openings through that area of said first polysilicon layer and said first oxide layer, to expose a second portion of the base substrate,
• (f) coating a second oxide layer over said second exposed portion of said substrate and the edges of the openings leading thereto and said first layer of polysilicon,
• (g) providing openings through both the first and second oxide layers to expose a third portion of said substrate,
• (h) adding a second coating of polysilicon to form a second polysilicon layer thereover and defining it, and
• (i) etching said first and second oxide layers to remove them completely, so that the first and second polysilicon layers become movable relative to each other.

A method for making a microminiature pin joint with two members relatively movable to each other, comprising the steps of;

• (a) cleaning thoroughly and preparing a silicon substrate wafer,
• (b) providing a first layer of an oxide thereon, said oxide having a high etching rate in a selected etching acid,
• (c) providing openings through said first oxide layer to expose a portion of said substrate,
• (d) depositing over said first oxide layer and the exposed portion of said substrate a first layer of polysilicon,
• (e) defining a selected area of said first layer of polysilicon and providing openings through that area of said first polysilicon layer and said first oxide layer, to expose a second portion of the base substrate,
• (f) coating a second oxide layer over said second exposed portion of said substrate and the edges of the openings leading thereto and said first layer of polysilicon,
• (g) providing openings through both the first and second oxide layers to expose a third portion of said substrate,
• (h) adding a second coating of polysilicon to form a second polysilicon layer thereover and defining it, and
• (i) etching said first and second oxide layers to remove them completely, so that the first and second polysilicon layers become movable relative to each other.

A method for making a microminiature pin joint with two members relatively movable to each other, comprising the steps of:

• (a) cleaning thoroughly and preparing a silicon substrate wafer,
• (b) providing a first layer of phosphosilicate glass thereon,
• (c) providing openings through said first phosphosilicate glass layer to expose a portion of said substrate,
• (d) depositing over said first phosphosilicate glass layer and the exposed portion of said substrate a first layer of polysilicon,
• (e) defining a selected area of said first layer of layer polysilicon and providing openings through that area of said first polysilicon layer and said first layer of coating to expose a second portion of said substrate,
• (f) coating a second phosphosilicate glass layer over said second exposed portion of said substrate and the edges of the openings leading thereto and said first layer of polysilicon,
• (g) providing openings through both the first and second layers of phosphosilicate glass to expose a third portion of said substrate,
• (h) adding a second coating of polysilicon to form a second polysilicon layer thereover and defining it, and
• (i) etching said first and second phosphosilicate glass layers to remove them completely, so that said first and second polysilicon layers become movable relative to each other.

A method for making a microminiature device having at least two members relatively movable to each other, comprising the steps of:

• (a) cleaning thoroughly and preparing a silicon substrate wafer,
• (b) providing a first layer of phosphosilicate glass thereon,
• (c) providing openings through said first phosphosilicate glass layer to expose a portion of said substrate,
• (d) depositing over said first phosphosilicate glass layer and the exposed portion of said substrate a first layer of polysilicon,
• (e) defining a selected area of said first layer of layer polysilicon and providing openings through that area of said first polysilicon layer and said first layer of coating to expose a second portion of said substrate,
• (f) coating a second phosphosilicate glass layer over said second exposed portion of said substrate and the edges of the openings leading thereto and said first layer of polysilicon,
• (g) providing openings through both the first and second layers of phosphosilicate glass to expose a third portion of said substrate,
• (h) adding a second coating of polysilicon to form a second polysilicon layer thereover and defining it, and
• (i) etching said first and second phosphosilicate glass layers to remove them completely, so that said first and second polysilicon layers become movable relative to each other.

A method for making a microminiature structure with a plurality of members measuring less than 1000 .mu.m in any linear dimension and relatively movable to each other, comprising the steps of:

• (a) providing a first sacrificial coating over a substrate having openings therethrough to expose a portion of the substrate,
• (b) depositing a first structural layer over said first sacrificial coating and the exposed portion of the substrate, with openings therethrough to expose a second portion of the substrate,
• (c) providing additional sacrificial coatings successively over such exposed portions of substrate and a said structural layer, with openings through said sacrificial layers to expose other portions of the substrate,
• (d) adding additional structural layers over each said sacrificial coating and defining it, and
• (e) etching the sacrificial layers to remove them completely so that the plurality of structural layers become movable relative to each other.