Process for forming and acoustically connecting structures on a substrate

• US 20040146810A1
• Filed: 01/23/2003
• Published: 07/29/2004
• Est. Priority Date: 01/23/2003
• Status: Active Grant

• Current Assignee: Akustica Incorporated (Robert Bosch GmbH)
• Original Assignee: Akustica Incorporated (Robert Bosch GmbH)
• Inventors: Zhu, Xu, Gabriel, Kaigham J.
• Granted Patent: US 7,049,051 B2
• Time in Patent Office: Days
• US Class Current: 430/322
• CPC Class Codes: A61K 2800/33 Free of surfactant
• CPC Class Codes: A61K 2800/58 Metal complex; Coordination compounds
• CPC Class Codes: A61K 2800/72 Hypo-allergenic
• CPC Class Codes: A61K 2800/75 Anti-irritant
• CPC Class Codes: A61K 2800/94 Involves covalent bonding to the substrate
• CPC Class Codes: A61K 8/0208 Tissues; Wipes; Patches
• CPC Class Codes: B81B 2201/0257 Microphones or microspeakers
• CPC Class Codes: B81C 1/00158 Diaphragms, membranes manufacture process for semi-permeable inorganic membranes B01D67/0039
• CPC Class Codes: H04R 19/005 using semiconductor materials

Abstract

The present invention describes a processes that builds an acoustic cavity, a chamber, and vent openings for acoustically connecting the chamber with the acoustic cavity. The dry etch processes may include reactive ion etches, which include traditional parallel plate RIE dry etch processes, advanced deep and inductively coupled plasma RIE processes. Three embodiments for connecting the chamber to the cavity from the top side of the substrate, e.g. by using pilot openings formed using at least a portion of the mesh as an etch mask, by forming the vent openings using at least a portion of the mesh as an etch mask, or by having the chamber intersect the vent openings as the chamber is being formed, illustrate how the disclosed process may be modified. By forming the cavity on the back side of the substrate, the depth of the vent holes is decreased. Additionally, using at least a portion of the micro-machined mesh as an etch mask for the vent holes makes the process self-aligning.

Claims

1. A process, comprising:

reducing the thickness of a back side of a substrate in an area where vents are to be formed;

releasing a mesh from a top side of the substrate; and

forming vent openings that connect the released mesh and the area of reduced thickness.

2. The process of claim 1 additionally comprising:

forming pilot openings in said substrate in said area of reduced thickness by using said mesh as an etch mask; and

wherein said releasing comprises removal of a portion of substrate beneath the mesh, and

wherein said forming is performed substantially simultaneously with said releasing.

3. The process of claim 2 additionally comprising applying and patterning a layer of resist to select certain portions of the mesh to act as said etch mask.

4. The process of claim 2 wherein an anisotropic etch is used to form said pilot openings and an isotropic etch is used for releasing the mesh and forming the vent openings.

5. The process of claim 1 wherein said forming is performed after said releasing.

6. The process of claim 5 wherein said forming comprises using said mesh as an etch mask.

7. The process of claim 6 wherein an isotropic etch is used for releasing the mesh and an anisotropic etch is used for said forming.

8. The process of claim 1 wherein said forming is performed from the back side of the substrate before said releasing.

9. The process of claim 8 wherein an anisotropic etch is used for said forming and an isotropic etch is used for said releasing.

10. A process of forming and connecting structures on a substrate, comprising:

forming an acoustic cavity from the back side of a substrate;

forming a chamber under a micro-machined mesh from the top side of the substrate; and

acoustically connecting the chamber with the acoustic cavity.

11. The process of claim 10 additionally comprising:

forming pilot openings in said substrate in an area where said acoustic cavity is located by using said mesh as an etch mask; and

wherein said forming a chamber comprises removing a portion of substrate from beneath the mesh, and

wherein said connecting comprises using said pilot openings to form vent openings substantially simultaneously with said forming a chamber.

12. The process of claim 11 additionally comprising applying and patterning a layer of resist to select certain portions of the mesh to act as said etch mask.

13. The process of claim 11 wherein an anisotropic etch is used to form said pilot openings and an isotropic etch is used for forming the chamber and to form the vent openings.

14. The process of claim 10 wherein said connecting is performed after said forming a chamber.

15. The process of claim 14 wherein said connecting comprises using said mesh as an etch mask to form vent openings.

16. The process of claim 15 wherein an isotropic etch is used for forming the chamber and an anisotropic etch is used to form said vent openings.

17. The process of claim 10 wherein said connecting comprises forming vent openings from the back side of the substrate before forming said chamber, and

wherein forming said chamber comprises removing a portion of substrate from beneath the mesh, and

wherein said connecting comprises said chamber intersecting said vent openings during the forming of said chamber.

18. The process of claim 17 wherein an anisotropic etch is used for forming said vent openings and an isotropic etch is used for forming said chamber.

19. A process, comprising:

forming a chamber under a micro-machined mesh; and

substantially simultaneously with the formation of said chamber, connecting said chamber a with a cavity formed on the back side of a substrate.

20. The process of claim 19 wherein said connecting comprises forming vent openings between the chamber and the cavity.

21. The process of claim 20 wherein said forming a chamber and forming vent openings comprises an isotropic etch.

22. The process of claim 19 additionally comprising forming vent openings from the back side of the substrate in the cavity, and wherein said connecting comprises said chamber intersecting said vent openings during said chamber'"'"'s formation.

23. The process of claim 22 wherein said forming a chamber and said connecting comprises an isotropic etch.

24. A process of acoustically connecting a chamber formed under a micro-machined mesh with a cavity formed on the back side of a substrate, comprising:

etching from the top side of the substrate to connect the chamber with the cavity.

25. The process of claim 24 wherein said etching includes forming vent openings in the substrate in the area of the cavity by using the micro-machined mesh as an etch mask.

26. The process of claim 25 wherein said etching includes an anisotropic etch.