Micromechanical device having an improved beam

• US 5,552,924 A
• Filed: 11/14/1994
• Issued: 09/03/1996
• Est. Priority Date: 11/14/1994
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Tregilgas, John H.
• Primary Examiner(s): Dzierzynski, Paul M.
• Assistant Examiner(s): Schuberg, Darren E.
• Application Number:
  US08/339,363
• Time in Patent Office: 659 Days
• Field of Search: 359/196, 359/198, 359/212, 359/214, 359/221, 359/223, 359/224, 359/234, 359/290, 359/291, 359/298, 359/318, 257/414, 257/415
• US Class Current: 359/224.1
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means

Abstract

An electrically addressable, integrated, monolithic, micromirror device (10) is formed by the utilization of sputtering techniques, including various metal and oxide layers, photoresists, liquid and plasma etching, plasma stripping and related techniques and materials. The device (10) includes a selectively electrostatically deflectable mass or mirror (12) of supported by one or more beams (18) formed by sputtering and selective etching. The beams (18) are improved by being constituted of an electrically conductive, intermetallic aluminum compound, or a mixture of two or more such compounds. The materials constituting the improved beams (18) have relatively high melting points, exhibit fewer primary slip systems than FCC crystalline structures, are etchable by the same or similar etchants and procedures used to etch aluminum and aluminum alloy, and are stronger and experience less relaxation than aluminum or aluminum alloys. Accordingly, the improved beams (18) exhibit increased strength, and decreased relaxation without requiring significant or radical deviations from the typical processing steps employed to produce the otherwise unaltered device.

Claims

1. An improved deformable beam for a micromechanical device of the type which includes a deflectable mass supported by the beam, which is deformable upon deflection of the mass, wherein the improvement comprises:

the beam being constituted of one or more electrically conductive aluminum compounds exhibiting fewer primary slip systems than FCC crystalline structures.

2. An improved deformable beam for a micromechanical device of the type which includes a deflectable mass supported by the beam, which is deformable upon deflection of the mass, wherein the improvement comprises:

the beam being constituted of one or more electrically conductive, aluminum intermetallic compounds.

3. An improved beam as in claim 2, wherein:

the compounds exhibit fewer primary slip systems than FCC crystalline structures.

4. An improved beam as in claim 3, wherein:

the micromechanical device is an SLM, and

the mass is a mirror.

5. An improved beam as in claim 4, wherein:

the aluminum compound has the general formula Al_x Q_y, where Q is not oxygen.

6. An improved beam as in claim 5, wherein:

Q is selected from the group consisting of iron, niobium, nickel, tantalum, zirconium, molybdenum, tungsten, arsenic, lithium, nitrogen, phosphorus, antimony and titanium.

7. An improved beam as in claim 6, wherein:

the beam is constituted of a mixture of the compounds.

8. An improved beam as in claim 7, wherein:

the mixture is AlTi and Al₃ Ti.

9. An improved beam as in claim 5, wherein:

Q is selected from the group consisting of antimony, arsenic, phosphorus and nitrogen.

10. An improved beam as in claim 4, wherein:

the aluminum compound is of the general formula Al_x Q_y, wherein Q is selected from the group consisting of metallic elements, rare earth elements, non-metallic solid elements and non-metallic gaseous elements.

11. An improved beam as in claim 10, wherein:

Q is a metallic element selected from the group consisting of iron, niobium, nickel, tantalum, zirconium, molybdenum, tungsten, lithium and titanium.

12. An improved beam as in claim 10, wherein:

Q is a non-metallic solid element selected from the group consisting of antimony, arsenic and phosphorus,

13. An improved beam as in claim 10, wherein:

Q is nitrogen.

14. An improved beam as in claim 10, wherein:

Q is selected from the group consisting of gold, calcium, copper, iron, hafnium, magnesium, niobium, nickel, scandium, tantalum, zirconium, barium, molybdenum, samarium, tungsten, ruthenium, vanadium, columbium, iridium, rhodium, lithium, antimony, titanium, cerium, gadolinium, holmium, lanthanum, lutetium, nadolinium, samarium, terbium, selenium, carbon, arsenic, boron, phosphorus and nitrogen.

15. An improved deformable beam for a micromechanical device of the type which includes a deflectable mass supported by the beam, deflection of the mass deforming the beam, wherein the improvement comprises:

the beam being constituted of a material selected from the group consisting of intermetallic compounds which include aluminum, compound semiconductors which include aluminum, compounds which include aluminum and a rare earth, and compounds which include aluminum and a non-metal.

16. A beam as in claim 15, wherein:

the material is selected from the consisting of Al₂ Au, Al₂ Ca, Al₂ Cu, Al₃ Fe, Al₃ Hf, Al₃ Mg₂, Al₃ Nb, Al₃ Ni, Al₃ Sc, Al₃ Ta, Al₃ Zr, Al₄ Ba, Al₄ Mo, Al₄ Sr, Al₄ W, Al₆ Ru, Al₇ Cr, Al₈ V₅, Al₉ Co₂, Al₉ Ir₂, Al₉ Rh₂, AlLi, Al₃ Ti and AlTi.

17. A beam as in claim 16, wherein:

the material is Al₃ Ti.

18. A beam as in claim 16, wherein:

the material is AlTi.

19. A beam as in claim 15, wherein:

the material is a mixture of Al₃ Ti and AlTi.

20. A beam as in claim 15, wherein:

the material is AlN.

21. A beam as in claim 15, wherein:

the material is a mixture of AlN and Al₃ Ti.

22. A beam as in claim 15, wherein:

the material is a compound semiconductor which includes aluminum.

23. A beam as in claim 22, wherein:

the material is AlSb, AlAs, AlP, or AlN.

24. A beam as in claim 15, wherein:

the material is a compound which includes aluminum and a rare earth.

25. A beam as in claim 24, wherein:

the material is Al₃ Ce, Al₃ Gd, Al₃ Ho, Al₃ La, Al₃ Lu, Al₃ Nd, Al₃ Sm or Al₃ Tb.

26. A beam as in claim 15, wherein:

the material is a compound which includes aluminum and a non-metal.

27. A beam as in claim 26, wherein:

the material is Al₂ Se₃, Al₄ C₃ or AlB₂.

28. An improved beam as in claim 15, wherein:

the material is etchable by the same or similar etchants and procedures used to etch aluminum and aluminum alloy.

29. An improved beam as in claim 15, wherein:

the beam is formed by sputtering.

30. An improved beam as in claim 15, wherein:

the material is stronger and experiences less relaxation than aluminum or aluminum alloys.

31. An improved deformable beam for a micromechanical device of the type which includes a deflectable mass supported by the beam, which is deformable upon deflection of the mass, wherein the improvement comprises:

the beam being constituted of one or a mixture of two or more electrically conductive aluminum compounds which

(a) exhibit fewer primary slip systems than FCC crystalline structures,

(b) are etchable by the same or similar etchants and procedures used to etch aluminum and aluminum alloy,

(b) being depositable by sputtering, and

(c) being stronger and experiencing less relaxation than aluminum or aluminum alloys.