Production method for integrated angular speed sensor device

• US 6,387,725 B1
• Filed: 02/22/2001
• Issued: 05/14/2002
• Est. Priority Date: 10/23/1997
• Status: Expired due to Term

• Current Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Original Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Inventors: Foroni, Mario, Montanini, Pietro, Ferrari, Paolo, Vigna, Benedetto, Ferrera, Marco
• Primary Examiner(s): Nguyen, Tuan H.
• Assistant Examiner(s): Thompson, Craig
• Application Number:
  US09/791,965
• Publication Number:
  US 20020022291A1
• Time in Patent Office: 446 Days
• Field of Search: 438/52, 438/48-51, 438/53, 438/42, 438/44-47, 438/689-690, 438/700, 438/880
• US Class Current: 438/52
• CPC Class Codes: G01C 19/574 the devices having two sensing masses in anti-phase motion
• CPC Class Codes: G01C 19/5769 Manufacturing; Mounting; Housings
• CPC Class Codes: G01P 15/0802 Details
• CPC Class Codes: H01L 21/76202 using a local oxidation of silicon, e.g. LOCOS, SWAMI, SILO H01L21/76235 takes precedence; together with vertical isolation, e.g. LOCOS in a SOI substrate, H01L21/76264
• CPC Class Codes: H01L 21/764 Air gaps H01L21/76264 takes precedence

Abstract

An angular speed sensor comprises a pair of mobile masses which are formed in an epitaxial layer and are anchored to one another and to the remainder of the device by anchorage elements. The mobile masses are symmetrical with one another, and have first mobile excitation electrodes which are intercalated with respective first fixed excitation electrodes and second mobile detection electrodes which are intercalated with second fixed detection electrodes. The first mobile and fixed excitation electrodes extend in a first direction and the second mobile and fixed detection electrodes extend in a second direction which is perpendicular to the first direction and is disposed on a single plane parallel to the surface of the device.

Claims

1. A method for production of an integrated angular speed sensor device, comprising:

forming a sacrificial region on a substrate of semiconductor material;

growing a pseudo-epitaxial layer including a polycrystalline epitaxial region in contact with the sacrificial region and a monocrystalline epitaxial region in contact with the substrate;

forming electronic elements in the monocrystalline epitaxial region;

removing selective portions of the polycrystalline epitaxial region thereby forming excitation electrodes that are intercalated with fixed excitation electrodes that extend in a first direction of extension;

forming mobile detection electrodes that are intercalated with fixed detection electrodes that extend in a second direction of extension which is substantially perpendicular to the first direction; and

forming a trench separating from one another the mobile and fixed excitation and detection electrodes; and

removing the sacrificial region through the trench.

2. A method according to claim 1 wherein removing the sacrificial region comprises removing a silicon oxide region.

3. A method according to claim 1 wherein the pseudo-epitaxial layer and the substrate have a first conductivity type, the method further comprising:

forming in the substrate buried contact regions with a second conductivity type before growing the pseudo-epitaxial layer;

forming regions of electrically isolating material extending above the buried contact regions and delimiting between one another selective contact portions of the buried contact regions;

forming a well region having the second conductivity type above the sacrificial region after growing the pseudo-epitaxial layer; and

forming sinker contact regions having the second conductivity type and extending from a surface of the pseudo-epitaxial layer as far as the buried contact regions thereby forming sinker contacts, after growing the pseudo-epitaxial layer.

4. A method according to claim 1, further comprising:

forming a first mask of silicon carbide above the pseudo-epitaxial layer, the first mask protecting regions beneath during the step of removing the sacrificial region; and

forming a second mask of silicon oxide above the first mask, the second mask protecting the first mask during the step of formation of the trench.

5. A method for production of an integrated angular speed sensor device, the method comprising:

forming a mobile structure flexibly anchored to a semiconductor body, the mobile structure including mobile excitation electrodes and mobile detection electrodes;

forming on the semiconductor body fixed excitation electrodes alternating with the mobile excitation electrodes, the mobile and fixed excitation electrodes having a first direction of extension;

forming on the semiconductor body fixed detection electrodes alternating with the mobile detection electrodes, the mobile and fixed detection electrodes having a second direction of extension at an angle to the first direction, the mobile and fixed excitation and detection electrodes all being in the plane of the surface; and

forming in the semiconductor body, prior to forming the mobile and fixed excitation and detection electrodes, a buried contact region that is doped to provide a conductive path, wherein one of the fixed excitation and detection electrodes is formed in connection with the buried contact region.

6. The method of claim 5 wherein the semiconductor body is a monocrystalline substrate, the method further comprising:

growing a monocrystalline epitaxial region in contact with the substrate and the buried contact region; and

forming electronic elements in the monocrystalline epitaxial region.

7. The method of claim 6, further comprising forming a conductive sinker contact region extending through the monocrystalline epitaxial region as far as the buried contact region, after growing the monocrystalline epitaxial region.

8. The method of claim 5 wherein forming the mobile structure and fixed excitation and detection electrodes includes:

forming a sacrificial region on the semiconductor body;

growing a polycrystalline epitaxial region in contact with the sacrificial region;

removing selective portions of the polycrystalline epitaxial region to form the mobile structure and fixed excitation and detection electrodes and a trench separating from one another the mobile and fixed excitation and detection electrodes; and

removing the sacrificial region through the trench to release the mobile structure from the semiconductor body.

9. A method according to claim 8, further comprising:

forming a first mask of silicon carbide above the polycrystalline epitaxial region, the first mask protecting regions beneath the first mask during the step of removing the sacrificial region; and

forming a second mask of silicon oxide above the first mask, the second mask protecting the first mask during the step of formation of the trench.

10. The method of claim 8 wherein the semiconductor body is a monocrystalline substrate, the method further comprising:

growing a monocrystalline epitaxial region in contact with the substrate and the buried contact region; and

forming electronic elements in the monocrystalline epitaxial region.