Method of making slotted diaphragm semiconductor devices

• US 4,867,842 A
• Filed: 05/16/1988
• Issued: 09/19/1989
• Est. Priority Date: 09/30/1982
• Status: Expired due to Term

• Current Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Original Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Inventors: Bohrer, Philip J., Johnson, Robert G.
• Primary Examiner(s): Powell, William A.
• Application Number:
  US07/194,366
• Time in Patent Office: 491 Days
• Field of Search: 156/647, 156/653, 156/656, 156/657, 156/659.1, 156/662, 29/610.1, 73/204, 73/719-721, 73/725-727, 357/26, 338/2-5, 338/25, 338/292, 338/293, 338/308, 338/309, 338/319
• US Class Current: 438/53
• CPC Class Codes: G01F 1/6845 Micromachined devices
• CPC Class Codes: G01F 1/698 Feedback or rebalancing circuits, e.g. self heated constant temperature flowmeters

Abstract

An integrated semiconductor device includes a semiconductor body with a first surface having a predetermined orientation with respect to a crystalline structure in the semiconductor body. The semiconductor body has a depression formed into the first surface of the body. A layer of thin film material covers at least a portion of the first surface and includes an electric, thermal-to-electric, or electric-to-thermal element. The diaphragm apparatus forms a slotted diaphragm substantially covering the depression. The slotted diaphragm includes one or more slots sized and oriented so that, in the fabrication of the device, an anisotropic etch placed on the slot or slots will completely undercut the diaphragm and form the depression. The electric, thermal-to-electric, or electric-to-thermal element is substantially supported by the diaphragm and, therefore, is substantially thermally and physically isolated from the semiconductor body.

Claims

1. 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 method comprising the steps of:

providing a semiconductor body with a first surface having a predetermined orientation with respect to a crystalline structure in the semiconductor body;

applying a layer of thin film material of which the diaphragm is comprised onto the first surface;

exposing an area of the first surface through a slot means in the layer of thin film material, the slot means being sized and oriented so that an anisotropic etch placed on the exposed surface area will undercut the diaphragm and form the depression; and

applying the anisotropic etch to the exposed surface area to undercut the diaphragm and create the depression.

2. The method of claim 1 wherein the layer of thin film material comprises a dielectric material.

3. The method of claim 2 wherein the dielectric material comprises silicon nitride.

4. 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 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;

providing a layer of thin film material of which the diaphragm is coomprised onto the first surface;

exposing an area of the first surface through a slot means in the layer of thin film material, the slot means being oriented at substantially 45 degrees to the <

110>

direction, the slot having a length which determines the maximum width of the depression as measured along the slot oriented at substantially 45 degrees to the <

100>

direction; and

applying an anisotropic etch to the exposed

surface area to undercut the diaphragm and create the depression.

5. The method of claim 4 wherein the layer of thin film material comprises a dielectric material.

6. The method of claim 5 wherein the dielectric material comprises silicon nitride.