Process for producing micromechanical sensors

• US 6,159,762 A
• Filed: 05/27/1999
• Issued: 12/12/2000
• Est. Priority Date: 11/28/1996
• Status: Expired due to Fees

• Current Assignee: Christofer Hierold, Thomas Scheiter, Ulrich Naher
• Original Assignee: Christofer Hierold, Thomas Scheiter, Ulrich Naher
• Inventors: Hierold, Christofer, Scheiter, Thomas, Naher, Ulrich
• Primary Examiner(s): Chaudhari, Chandra
• Assistant Examiner(s): CHRISTIANSON, KEITH ALAN
• Application Number:
  US09/308,985
• Time in Patent Office: 565 Days
• Field of Search: 73/718, 73/724, 257/415, 361/283.1, 361/283.3, 361/283.4, 438/50, 438/52, 438/53
• US Class Current: 438/53
• CPC Class Codes: G01L 9/0042 Constructional details associated with semiconductive diaphragm sensors, e.g. etching, or constructional details of non-semiconductive diaphragms details about the integration or bonding of piezoresistor in or on the diaphragm G01L9/0052 and G01L9/0057 respectively
• CPC Class Codes: G01L 9/0073 using a semiconductive diaphragm

Abstract

Method for manufacturing an absolute pressure sensor as micromechanical component on a silicon substrate, whereby a cavity (4) is etched out in an auxiliary layer (3) under a membrane layer (5) through etching openings (6), the etching openings are closed with a passivation layer (7), whereby a specific etching opening (11) is re-opened in a via hole etching and this opening is re-closed with a metallization or dielectric material (10, 12) in a following process step that ensues at low pressure.

Claims

1. A method for manufacturing a micromechanical sensor, comprising the following steps:

a) applying a second layer onto a first layer provided for manufacture of a cavity;

b) using a mask, producing recesses having a size dimensioned for following steps c) and d) in the second layer in a region of a projection of the cavity to be manufactured that is perpendicular relative to layer planes of the first and second layers;

c) upon employment of the recesses, etching a cavity out in the first layer;

d) applying a closure layer onto the second layer such that the recesses are closed without filling up the cavity;

e) re-opening at least one of the recesses in the second layer at least to such an extent that the cavity is opened; and

f) re-closing the at least one recess with a material that differs from a material of the closure layer so that the cavity is closed.

2. A method according to claim 1, wherein the closure layer applied in step d) is composed of borophosphorous silicate glass.

3. A method according to claim 1, wherein, in step f, said re-closing is by a metal sputtering.

4. A method according to claim 1, wherein the steps f includes enclosing a gas in the cavity thereafter resides under a pressure of at most 2000 Nm^-2 at room temperature.

5. A method according to claim 1, further comprising the steps of:

aa) producing an electrically conductively doped region at an upper side of a substrate of semiconductor material before step a and producing the first layer over the electrically conductively doped region;

a2) in step a, the second layer is at least partially electrically conductively; and

e1) in step e, simultaneously producing via holes for electrical contacting of the second layer as said re-opening step is performed.

6. A method according to claim 1, wherein

in step a, the second layer includes a first portion which is a membrane layer for an absolute pressure sensor and a second portion distinct from the membrane layer;

in step b, producing at least one of the recesses in the second portion; and

in step e, the at least one recess which is re-opened is in the second portion.

7. A method according to claim 1, further comprising the steps of:

applying the first layer as a layer sequence that contains a structured layer provided as a mass part of an acceleration sensor; and

in step c, the etching is implemented such that the mass part is etched free in the cavity.

8. A method according to claim 1, wherein, in step f, said re-closing is by a deposition of a dielectric.

9. A method as claimed in claim 1, wherein said first layer is a layer sequence.

10. A method as claimed in claim 1, wherein said second layer is a layer sequence.