Method of making a micromechanical device

• US 6,706,548 B2
• Filed: 01/08/2002
• Issued: 03/16/2004
• Est. Priority Date: 01/08/2002
• Status: Expired due to Term

• Current Assignee: North Star Innovations Inc. (Wi-LAN Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Liu, Lianjun
• Primary Examiner(s): Whitehead, Jr., Carl
• Assistant Examiner(s): Vesperman, William C
• Application Number:
  US10/041,337
• Publication Number:
  US 20030129824A1
• Time in Patent Office: 798 Days
• Field of Search: 200/181, 200/245, 200/246, 333/262, 333/101, 333/105, 310/309, 438/623, 438/52, 438/50, 438/589, 438/637, 438/622, 438/638, 250/774, 250/775, 250/773
• US Class Current: 438/52
• CPC Class Codes: B81B 7/0006 Interconnects

Abstract

A method of making a micromechanical device including forming recesses (28) using two sacrificial layers (22 and 27). A first sacrificial layer (22) is formed over an input signal line (16) and an output signal line (17). A portion of the first sacrificial layer (22) is removed to form openings (26) over the input signal line (16) and the output signal line (17). A second sacrificial layer (27) is formed over the first sacrificial layer (22) and openings (26) to form recesses (28) over the openings (26). A conductive layer (32) is formed over the second sacrificial layer (27) and the recesses (28). The conductive layer (32) serves as a shorting bar of a cantilever beam structure that couples input signal line (16) to output signal line (17) during operation.

Claims

1. A method of making a microelectronic device comprising the steps of:

providing a substrate;

forming an input signal line over the substrate;

forming an output signal line over the substrate and spaced apart from the input signal line;

forming a first sacrificial layer over the input signal line and the output signal line;

removing a portion of the first sacrificial layer over the input signal line to form a first opening and over the output signal line to form a second opening;

forming a second sacrificial layer over the first sacrificial layer, the first opening, and the second opening, wherein a first recess and a second recess are formed over the first opening and the second opening; and

forming a conductive layer over a portion of the second sacrificial layer, the first recess, and the second recess, wherein the step of forming the second sacrificial layer comprises forming a second polyimide layer.

2. The method of claim 1, wherein the step of forming the first sacrificial layer comprises forming a first polyimide layer.

3. The method of claim 2, further comprising the step of heating the first sacrificial layer at a temperature below or equal to approximately 250°

C. so that the first sacrificial layer is only partially cured.

4. The method of claim 1, further comprising the step of heating the second sacrificial layer at a temperature above 250°

C. so that the second sacrificial layer is substantially fully cured.

5. The method of claim 1, wherein the step of forming the first sacrificial layer comprises forming the first sacrificial layer having a thickness of approximately 0.5 to 2 microns.

6. The method of claim 1, wherein the step of removing a portion of the first sacrificial layer comprises:

forming a photoresist layer over the first sacrificial layer,

patterning the photoresist layer to use as a mask to form the first opening and the second opening,

removing the photoresist layer prior to the step of forming the second sacrificial layer.

7. The method of claim 1, wherein the step of removing a portion of the first sacrificial layer comprising using a dry etch.

8. The method of claim 1, wherein the step of forming the second sacrificial layer comprises the first recess and the second recess being formed in absence of an etch step.

9. A method of making a microelectronic device comprising the steps of:

providing a substrate;

forming an input signal line over the substrate;

forming an output signal line over the substrate and spaced apart from the input signal line;

forming a first sacrificial layer over the input signal line and the output signal line;

removing a portion of the first sacrificial layer over the input signal line to form a first opening and over the output signal line to form a second opening;

forming a second sacrificial layer over the first sacrificial layer, the first opening, and the second opening, wherein a first recess and a second recess are formed over the first opening and the second opening; and

forming a conductive layer over a portion of the second sacrificial layer, the first recess, and the second recess, further comprising the steps of;

forming a dielectric layer over the second sacrificial layer and the conductive layer; and

removing the first sacrificial layer and the second sacrificial layer to form a cantilever beam structure comprised of the conductive layer and the dielectric layer above the input signal line and the output signal line.

10. A method of making a microelectronic device comprising the steps of:

providing a substrate;

forming an input signal line and an output signal line over the substrate;

forming a first sacrificial layer over the substrate, the input signal line and the output signal line;

heating the first sacrificial layer;

dry etching a portion of the first sacrificial layer over the input signal line to form a first opening and over the output signal line to form a second opening;

forming a second sacrificial layer over the first sacrificial layer, the first opening, and the second opening to form a fist recess over the first opening and a second recess over the second opening, whereby the first recess and the second recess have rounded edges; and

heating the second sacrificial layer;

forming a conductive layer over the second sacrificial layer, the first recess, and the second recess;

forming a dielectric layer over the conductive layer and the second sacrificial layer;

removing the first and the second sacrificial layers to create a cantilever beam comprised of the dielectric layer and the conductive layer.

11. The method of claim 10, wherein the step of forming the first sacrificial layer comprises forming a first polyimide layer and the step of forming the second sacrificial layer comprises forming a second polyimide layer.