Micro-electromechanical switch fabricated by simultaneous formation of a resistor and bottom electrode

• US 6,977,196 B1
• Filed: 08/18/2003
• Issued: 12/20/2005
• Est. Priority Date: 08/28/2001
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Jacobsen, Stuart M., Crenshaw, Darius L., Seymour, David J.
• Primary Examiner(s): Nhu, David
• Application Number:
  US10/642,969
• Time in Patent Office: 855 Days
• Field of Search: 438/381, 438/382, 438/384, 438/385, 438/238, 438/329, 438/330, 438/704, 438/706, 438/745, 438/171, 438/190, 438/210
• US Class Current: 438/238
• CPC Class Codes: H01H 1/0036 Switches making use of microelectromechanical systems [MEMS] for electromagnetic relays H01H50/005; for electrostatic relays H01H59/0009
• CPC Class Codes: H01H 59/0009 making use of micromechanics
• CPC Class Codes: Y10T 29/435 Solid dielectric type
• CPC Class Codes: Y10T 29/49004 including measuring or testing of device or component part
• CPC Class Codes: Y10T 29/4902 Electromagnet, transformer or inductor
• CPC Class Codes: Y10T 29/49071 by winding or coiling
• CPC Class Codes: Y10T 29/49117 Conductor or circuit manufacturing

Abstract

The present invention provides a method and product-by-method of integrating a bias resistor in circuit with a bottom electrode of a micro-electromechanical switch on a silicon substrate. The resistor and bottom electrode are formed simultaneously by first sequentially depositing a layer of a resistor material (320), a hard mask material (330) and a metal material (340) on a silicon substrate forming a stack. The bottom electrode and resistor lengths are subsequently patterned and etched (350) followed by a second etching (360) process to remove the hard mask and metal materials from the defined resistor length. Finally, in a preferred embodiment, the bottom electrode and resistor structure is encapsulated with a layer of dielectric which is patterned and etched (370) to correspond to the defined bottom electrode and resistor.

Claims

1. A method to form a RF switch by integrating a resistor in circuit with a bottom electrode of a micro-electromechanical switch on a substrate, said method comprising the steps of:

depositing a uniform layer of a resistor material over at least one side of said substrate;

depositing a uniform layer of a hard masked material over said resistor material;

depositing a uniform layer of a metal material over said hard mask material,

wherein said deposited layers form a stack;

patterning and etching said bottom electrode of said micro-electromechanical switch and resistor lengths from said stack; and

etching said hard mask and metal material from said patterned resistor length to form said RF switch.

2. The RF switch of claim 1, wherein said hard mask and metal material remain substantially covering said patterned bottom electrode subsequent to said etching said hard mask and metal material from said patterned resistor length.

3. The RF switch of claim 2, further comprising the step of depositing a dielectric over said patterned bottom electrode and resistor following said etching of said hard mask and metal material from said patterned resistor length.

4. The RF switch of claim 3, further comprising the step of patterning and etching said deposited dielectric to correspond to said pattern bottom electrode and resistor lengths.

5. The RF switch of claim 3, wherein said act of depositing a dielectric is performed immediately subsequent to etching said hard mask and metal material from said patterned resistor length.

6. The RF switch of claim 1, wherein said substrate comprises a deposited uniform layer of an anchor material comprising SiO₂.

7. The RF switch of claim 1 wherein said resistor material comprises NiCr.

8. The RF switch of claim 1, wherein said metal material comprises Al—

Si.

9. The RF switch of claim 1, wherein at least one of said etching acts comprises wet etching.