MEMS device with integral packaging

• US 8,179,215 B2
• Filed: 10/30/2007
• Issued: 05/15/2012
• Est. Priority Date: 11/29/2000
• Status: Expired due to Fees

• Current Assignee: Microassembly Technologies Incorporated
• Original Assignee: Microassembly Technologies Incorporated
• Inventors: Cohn, Michael Bennett, Xu, Ji-Hai
• Primary Examiner(s): Rojas, Bernard
• Application Number:
  US11/929,245
• Publication Number:
  US 20080272867A1
• Time in Patent Office: 1,659 Days
• Field of Search: 335/78, 200/181
• US Class Current: 335/78
• CPC Class Codes: B81B 2201/018 Switches not provided for in B81B2201/014 - B81B2201/016
• CPC Class Codes: B81B 2203/0118 Cantilevers
• CPC Class Codes: B81B 2207/093 Conductive package seal
• CPC Class Codes: B81B 7/0077 Other packages not provided for in groups B81B7/0035 - B81B7/0074
• CPC Class Codes: B81C 1/00301 Connecting electric signal lines from the MEMS device with external electrical signal lines, e.g. through vias
• CPC Class Codes: B81C 1/00357 involving bonding one or several substrates on a non-temporary support, e.g. another substrate
• CPC Class Codes: B81C 2201/019 Bonding or gluing multiple substrate layers
• CPC Class Codes: B81C 2203/0109 Bonding an individual cap on the substrate
• CPC Class Codes: B81C 2203/0118 Bonding a wafer on the substrate, i.e. where the cap consists of another wafer
• CPC Class Codes: B81C 2203/019 characterised by the material or arrangement of seals between parts
• CPC Class Codes: B81C 3/001 Bonding of two components
• CPC Class Codes: H01H 2059/0018 Special provisions for avoiding charge trapping, e.g. insulation layer between actuating electrodes being permanently polarised by charge trapping so that actuating or release voltage is altered
• CPC Class Codes: H01H 2059/0072 with stoppers or protrusions for maintaining a gap, reducing the contact area or for preventing stiction between the movable and the fixed electrode in the attracted position
• CPC Class Codes: H01H 59/0009 making use of micromechanics

Abstract

A MEMS device and method of making same is disclosed. In one embodiment, a micro-switch includes a base assembly comprising a movable structure bearing a contact pad. The base assembly is wafer-scale bonded to a lid assembly comprising an activator and a signal path. The movable structure moves within a sealed cavity formed during the bonding process. The signal path includes an input line and an output line separated by a gap, which prevents signals from propagating through the micro-switch when the switch is deactivated. In operation, a signal is launched into the signal path. When the micro-switch is activated, a force is established by the actuator, which pulls a portion of the movable structure upwards towards the gap in the signal path, until the contact pad bridges the gap between the input line and output line, allowing the signal to propagate through the micro-switch. Prior to bonding, the MEMS structures are annealed on a first wafer and the conductive traces and other metals are annealed on a second wafer to allow each wafer to be processed separately using different processes, e.g., different annealing temperatures.

Claims

1. A lid assembly for a micro-switch having a lid assembly and a base assembly, the lid assembly comprising:

a substrate;

a first insulating layer formed on the substrate;

a first conductive layer formed on the first insulating layer;

a signal path formed in the conductive layer and having a gap for preventing signals from propagating on the signal path;

an actuator formed in the first conductive layer for providing a force on a movable structure in the base assembly when the actuator is activated;

a second insulating layer formed on the first conductive layer;

an insulating ring formed in the second insulating layer;

a second conductive layer formed on the second insulating layer; and

a conductive ring formed in the second conductive layer, the conductive ring substantially aligned with and overlying the insulating ring, the conductive ring forming a seal around the movable structure when the lid assembly is bonded to the base assembly.

2. The lid assembly in claim 1, wherein the signal path extends under the insulation ring and outside of the cavity at two or more locations to connect with at least one contact point external to the insulation ring.

3. A base assembly for a micro-switch having a lid assembly and a base assembly, comprising:

a substrate;

a sacrificial layer formed on the substrate;

a structural layer formed on the sacrificial layer;

an insulating layer formed on the structural layer;

an insulating pad formed in the insulating layer;

a movable structure formed in the structural layer and the sacrificial layer, the movable structure bearing the insulating pad;

a pedestal formed in the sacrificial layer on the substrate, the pedestal contacting and supporting the movable structure so that the movable structure does not directly contact the substrate; and

a contact pad formed on the insulating pad, the contact pad for bridging a gap in a signal path on the lid assembly, when the movable structure is pulled towards the lid assembly in response to a force provided by an actuator in the lid assembly.

4. A method of making a lid assembly for a micro-switch having a lid assembly and a base assembly, the method comprising:

forming a first insulating layer on a substrate;

forming a first conductive layer on the first insulating layer;

forming a signal path and an actuator in the first conductive layer, the signal path having a gap for preventing signals from propagating on the signal path, the actuator for providing a force on a movable structure in the base assembly when the actuator is activated

forming a second insulating layer on the first conductive layer;

forming an insulating ring in the second insulating layer;

forming a second conductive layer on the second insulating layer; and

forming a conductive ring in the second conductive layer, the conductive ring substantially aligned with and overlying the insulating ring, the conductive ring for making a seal between the lid assembly and the base assembly.