Micro electronic element and method of making same

• US 5,406,109 A
• Filed: 10/28/1992
• Issued: 04/11/1995
• Est. Priority Date: 10/28/1992
• Status: Expired due to Fees

• Current Assignee: Julie G. Whitney
• Original Assignee: Julie G. Whitney
• Inventors: Whitney, Julie G.
• Primary Examiner(s): WOJCIECHOWICZ, EDWARD JOSEPH
• Application Number:
  US07/967,803
• Time in Patent Office: 895 Days
• Field of Search: 257/467, 257/419, 257/466, 257/522, 257/528, 257/619
• US Class Current: 257/467
• CPC Class Codes: G01F 1/6845 Micromachined devices
• CPC Class Codes: G01K 7/226 using microstructures, e.g. silicon spreading resistance
• CPC Class Codes: G01P 15/0802 Details
• CPC Class Codes: G01P 5/10 by measuring thermal variables

Abstract

A miniature electronic element is provided formed of and within a single crystal of semiconductor material on which are formed top and bottom surface layers of an oxide of the semiconductor material, and including at least one isolated island of semiconductor material formed in the remaining material between the top and bottom surface layers. Contact members may be attached in predetermined spatial relation to at least one of the top and bottom surface layers and extend through the one surface to the island of material connecting thereto in spaced relation, whereby the material of the island between the contact members provides an electrical path of predetermined value between the contact members. An isolating chamber (or chambers) is formed between the surface layers around the isolated island of material to provide thermal isolation to the island of material. A temperature sensing device is described using such miniature electronic sensing element, by applying an electrical potential across the leads to produce predetermined heating of the island of material, whereby changes in ambient conditions around the sensing element will be reflected as resistance changes in the island of material. Also described are novel methods of making such miniature electronic elements, including novel ways to form islands of semiconductor material within a crystal thereof.

Claims

1. A miniature electronic element formed of and within a single crystal of semiconductor material, comprising

top and bottom surface layers integral with said crystal and formed of an oxide of the semiconductor material, said layers being an integral part of said crystal,

at least one isolated island of non-oxidized semiconductor material remaining between and integral with said top and bottom surface layers internally of said crystal,

an isolating chamber formed within said crystal between said surface layers and around said island of semiconductor material to provide thermal isolation to the island of material except where said surface layers are integral with said island, and

contact members attached in predetermined spaced relation to one of said top and bottom surface layers and extending through said one surface layer to said island of semiconductor material and being connected thereto in spaced relation whereby the semiconductor material of the island between said contact members provides an electrical thermistor of predetermined value between said contact members.

2. A miniature electronic element as defined in claim 1, wherein at least one of said surface layers has sufficient thickness and rigidity to provide integrity to the structure of the semiconductor crystal element.

3. A miniature electronic sensing element as defined in claim 1, further including

means for applying an electric potential across said contact members so as to produce heating of said island of semiconductor material,

said chamber providing a thermal barrier around said island of semiconductor material and said oxide surface layers providing a thermal barrier at the top and bottom of said island of semiconductor material,

whereby changes in the ambient conditions around said sensing element will be reflected as resistance changes in said island of semiconductor material.

4. A miniature sensor element formed of a single crystal wafer of semiconductor material, comprising

front and back surface layers of the oxide of the wafer material formed on said wafer integrally therewith in predetermined spaced apart locations to provide a double-walled diaphragm of predetermined thickness,

a chamber formed internally of said crystal wafer between said oxide layers, said chamber surrounding and defining an island of the semiconductor material located between the walls of said diaphragm, and

output means attached to said diaphragm to provide a variable sensor output in response to changes in the physical condition of said island of semiconductor material.

5. A sensor element as defined in claim 4, wherein said island of material functions as a thermistor of known value, and said output means includes electrical contacts extending through at least one of said front and back surface layers to said island for applying a predetermined electrical potential to said island of semiconductor material, whereby heat exchange through said surface layers between the heated island of material and the ambient surroundings of said sensor element will be indicative of changing of temperature differential between said island of material and the surrounding atmosphere.