Micromechanical capacitive pressure transducer and production method

• US 8,492,855 B2
• Filed: 11/22/2006
• Issued: 07/23/2013
• Est. Priority Date: 12/20/2005
• Status: Expired due to Fees

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Lammel, Gerhard, Benzel, Hubert, Armbruster, Simon, Schelling, Christoph, Brasas, Joerg
• Primary Examiner(s): Vargot, Mathieu D.
• Application Number:
  US12/086,829
• Publication Number:
  US 20090101997A1
• Time in Patent Office: 2,435 Days
• Field of Search: 427/162, 257/415, 257/E21.09, 257/E29.324, 257/414, 257/417, 257/419, 438/52, 438/53
• US Class Current: 257/414
• CPC Class Codes: G01L 9/0073 using a semiconductive diaphragm

Abstract

The present invention describes a method for producing a micromechanical capacitive pressure transducer and a micromechanical component produced by this method. First, a first electrode is produced in a doped semiconductor substrate.

In a further method step, a diaphragm with a second electrode is produced at the surface of the semiconductor substrate. Furthermore, it is provided to apply a first layer, which preferably is made of dielectric material, on the diaphragm and the semiconductor substrate. With the aid of this first layer, the diaphragm and the semiconductor substrate of the finished micromechanical capacitive pressure transducer are mechanically connected to one another directly or indirectly. Furthermore, a buried cavity is produced in the semiconductor substrate between the first and second electrode. In a following etching step, the diaphragm is finally dissolved out of the semiconductor substrate through openings in the first layer, the mechanical connection from the diaphragm to the semiconductor substrate being accomplished with the aid of the first layer. Due to this mechanical connection the diaphragm or the second electrode is able to be movably suspended above the first electrode.

Claims

1. A mechanical component, comprising:

a first electrode within a silicon semiconductor substrate;

a diaphragm having an epitaxy layer and a second electrode;

a first layer on the diaphragm and the semiconductor substrate;

a cavity buried between the first electrode and the second electrode; and

a second layer, which includes polysilicon, situated on the first layer above an edge region of the diaphragm, the second layer being configured as a spring-type suspension of the diaphragm in at least one section of the edge region of the diaphragm, and wherein the second layer is structured into multiple elements that are not connected to each other and that are at least one of spatially restricted, which jointly form the spring-type suspension of one of the diaphragm and the second electrode, and allow an electrical contacting of the second electrode;

wherein the diaphragm is held above the first electrode by the first layer so as to allow movement, and the second electrode is laterally set apart from the semiconductor substrate, and

wherein the micromechanical component is made by performing the following;

producing the first electrode within a silicon semiconductor substrate;

producing a monocrystalline, lattice-like structure for forming the second electrode above a first region, etched to be porous, in the silicon semiconductor substrate;

applying an epitaxy layer on the silicon semiconductor substrate and the second electrode;

applying the first layer on the epitaxy layer;

producing the buried cavity between the first electrode and the second electrode by the first region; and

forming the diaphragm on the second electrode above the first porous region by separating the epitaxy layer on the second electrode from the epitaxy layer on the semiconductor substrate with an etching process, wherein the separation produces a flexible, mechanical connection between the diaphragm and the silicon semiconductor substrate by the first layer.

2. The micromechanical component of claim 1, wherein contacting of the second electrode is implemented through the epitaxy layer.

3. The micromechanical component of claim 1, wherein the first layer has a topology in an edge region of the cavity.

4. The micromechanical component of claim 1, wherein at least one of the first layer and the second layer includes sacrificial-layer etching holes, the sacrificial-layer etching holes being sealed by one of an oxide and a fill-in material.

5. The micromechanical component of claim 2, wherein the component is usable as one of an absolute-pressure sensor, a relative-pressure sensor, a microphone, or an acceleration sensor, and

wherein when the component is usable as the relative-pressure sensor or the microphone, the relative-pressure sensor or the microphone has at least one of a cavity, introduced from a rear side of the semiconductor substrate, and the first electrode has at least one through hole.

6. The micromechanical component of claim 1, wherein the buried cavity is at least partially surrounded by an edge region, and wherein a doping of the edge region and a doping of the first electrode and the second electrode are of a different type.