Slotted diaphragm semiconductor device

An integrated semiconductor device, comprising:

• a semiconductor body having a depression formed into a first surface of the body, the semiconductor body comprising (100) silicon and having a (100) plane and a [110] direction, the first surface of the semiconductor body being substantially parallel to the (100) plane;
• a layer of thin film material covering at least a portion of the first surface;
• and
• diaphragm means comprising the layer of thin film material and further comprising a thermal-to-electric transducing element and forming a slotted diaphragm substantially covering the depression, the depression being bounded at the first surface by a substantially square configuration comprising four substantially perpendicular boundary edges, each of the four substantially perpendicular boundary edges being substantially in line with or substantially perpendicular to the [110] direction, the slotted diaphragm comprising slot means comprising first and second slots located on a line oriented at substantially 45 degrees to the [110] direction, each of the first and second slots comprising a first end located at a maximum width of the depression as measured along the line oriented at substantially 45 degrees to the [110] direction, each of the first and second slots having a second end located so that each of the first and second slots extend only a portion of the distance across the maximum width of the depression as measured along the line oriented at substantially 45 degrees to the [110] direction, the slot means further comprising third, fourth, fifth and sixth slots oriented substantially in line with or substantially perpendicular to the [110] direction, there being one of the third, fourth, fifth and sixth slots located at the substantial center of each of the four boundary edges, each of the third, fourth, fifth and sixth slots having a length sufficient to permit undercutting of the diaphragm when an anisotropic etch is placed on each of the six slots.

An integrated semiconductor device, comprising:

• a semiconductor body having a depression formed into a first surface of the body, the semiconductor body comprising (100) silicon and having a (100) plane and a [110] direction, the first surface of the semiconductor body being substantially parallel to the (100) plane;
• a layer of thin film material covering at least a portion of the first surface;
• and
• diaphragm means comprising the layer of thin film material and further comprising an electric-to-thermal element and forming a slotted diaphragm substantially covering the depression, the depression being bounded at the first surface by a substantially square configuration comprising four substantially perpendicular boundary edges, each of the four substantially perpendicular boundary edges being substantially in line with or substantially perpendicular to the [110] direction, the slotted diaphragm comprising slot means comprising first and second slots located on a line oriented at substantially 45 degrees to the [110] direction, each of the first and second slots comprising a first end located at a maximum width of the depression as measured along the line oriented at substantially 45 degrees to the [110] direction, each of the first and second slots having a second end located so that each of the first and second slots extends only a portion of the distance across the maximum width of the depression as measured along the line oriented at substantially 45 degrees to the [110] direction, the slot means further comprising third, fourth, fifth and sixth slots oriented substantially in line with or substantially perpendicular to the [110] direction, there being one of the third, fourth, fifth and sixth slots located at the substantial center of each of the four boundary edges, each of the third, fourth, fifth and sixth slots having a length sufficient to permit undercutting of the diaphragm when an anisotropic etch is placed on each of the six slots.

A flow sensor, comprising:

• a semiconductor body having a depression formed into a first surface of the body, the semiconductor body comprising (100) silicon and having a (100) plane and a [110] direction, the first surface of the semiconductor body being substantially parallel to the (100) plane;
• a layer of thin film material covering at least a portion of the first surface;
• diaphragm means comprising the layer of thin film material and forming a slotted diaphragm substantially covering the depression, the depression being bounded at the first surface by a substantially square configuration comprising four substantially perpendicular boundary edges, each of the four substantially perpendicular boundary edges being substantially in line with or substantially perpendicular to the [110] direction, the slotted diaphragm comprising slot means comprising first and second slots located on a line oriented at substantially 45 degrees to the [110] direction, each of the first and second slots comprising a first end located at a maximum width of the depression as measured along the line oriented at substantially 45 degrees to the [110] direction, each of the first and second slots having a second end located so that each of the first and second slots extend only a portion of the distance across the maximum width of the depression as measured along the line oriented at substantially 45 degrees to the [110] direction, the slot means further comprising third, fourth, fifth and sixth slots oriented substantially in line with or substantially perpendicular to the [110] direction, there being one of the third, fourth, fifth and sixth slots located at the substantial center of each of the four boundary edges, each of the third, fourth, fifth and sixth slots having a length sufficient to permit undercutting of the diaphragm when an anisotropic etch is placed on each of the six slots;
• a thin film heater supported over the depression by the diaphragm, approximately half of the heater being located on each side of the line oriented at substantially 45 degrees to the [110] direction;
• and
• a pair of thin film heat sensors supported by the diaphragm, the thin film heat sensors being disposed on opposite sides of the heater.

A method of fabricating a slotted diaphragm semiconductor device comprising a slotted diaphragm of thin film material substantially covering a depression etched into a first surface of a semiconductor body, the depression being bounded at the first surface by a substantially square configuration comprising four substantially perpendicular boundary edges, each of the four substantially perpendicular boundary edges being substantially in line with or substantially perpendicular to a [110] direction in the semiconductor body, the method comprising the steps of:

• providing a semiconductor body comprising (100) silicon and having a (100) plane and a [110] direction, the first surface of the semiconductor body being substantially parallel to the (100) plane;
• exposing first and second areas of the first surface through first and second slots in the layer of thin film material, the first and second slots being located on a line oriented at substantially 45 degrees to the [110] direction, each of the first and second slots comprising a first end located at a maximum width of the depression as measured along the line oriented at substantially 45 degrees to the [110] direction, each of the first and second slots having a second end located so that each of the first and second slots extends only a portion of the distance across the maximum width of the depression as measured along the line oriented at substantially 45 degrees to the [110] direction;
• exposing third, fourth, fifth and sixth areas of the first surface through third, fourth, fifth and sixth slots oriented substantially in line with or substantially perpendicular to the [110] direction, there being one of the third, fourth, fifth and sixth slots located at the substantial center of each of the four boundary edges, each of the third, fourth, fifth and sixth slots having a length sufficient to permit undercutting of the diaphragm when an anisotropic etch is placed on each of the six slots;
• and
• applying the anisotropic etch to the exposed surface areas to undercut the diaphragm and create the depression.