Method for processing a thin film micro device on a substrate

• US 8,507,385 B2
• Filed: 05/05/2009
• Issued: 08/13/2013
• Est. Priority Date: 05/05/2008
• Status: Active Grant

• Current Assignee: XI'AN Yisheng Optoelectronics Technology Co., Ltd.
• Original Assignee: Shanghai Lexvu Opto Microelectronics Technology Co., Ltd.
• Inventors: Tang, Deming
• Primary Examiner(s): Campbell, Shaun
• Application Number:
  US12/435,835
• Publication Number:
  US 20090275203A1
• Time in Patent Office: 1,561 Days
• Field of Search: 438/703, 438/704, 438 50- 57, 438/745, 438/751, 257415-420, 257E29323-E29325, 257/710, 257/E21.499
• US Class Current: 438/703
• CPC Class Codes: B81C 1/0015 Cantilevers switches using MEMS H01H1/0036; electrostatic relays using micromechanics H01H59/0009; microelectro-mechanical resonators H03H9/02244

Abstract

A method for processing a thin film micro device on a substrate includes: 1) depositing a carbon film on the substrate as a sacrificial layer; 2) photolithographically defining a first predetermined pattern in the carbon film; 3) etching an unwanted portion of the carbon film outside the first predetermined pattern; 4) depositing a structural film including a single or multiple layers of solid state materials; 5) photolithographically defining a second predetermined pattern in the structural film; 6) etching the discarded portion of the structural film outside the second predetermined pattern; 7) selectively removing the remaining portion of the sacrificial carbon film by using a selective etch process gas in a reactor chamber, so that the overlapped portion of the remaining structural element with the first predetermined pattern is suspended above an underneath cavity above the substrate.

Claims

1. A method for processing a thin film micro device on a substrate, comprising:

depositing a carbon film on the substrate;

photolithographically defining a first predetermined pattern in the carbon film;

etching an unwanted portion of the carbon film outside the first predetermined pattern where the substrate is exposed to form an exposed portion, wherein a remaining portion of the carbon film defined within the first predetermined pattern stays adherent to the substrate;

depositing a structural film comprising a single or multiple layers of solid state materials conformal and adherent to both the exposed portion of the substrate and the remaining portion of the carbon film, wherein the structural film comprises layers selected from polycrystalline silicon, amorphous silicon, single-crystal silicon, silicon dioxide, silicon nitride, silicon carbide, organosilicate glass, tungsten carbide, and aluminum carbide;

photolithographically defining a second predetermined pattern in the structural film;

etching a discarded portion of the structural film outside the second predetermined pattern, wherein the first predetermined pattern is not fully enclosed by the second predetermined pattern so that part of the remaining portion of the carbon film remains exposed on its top surface and/or at its sidewalls, and is not fully covered spatially by the remaining structural element of the structural film; and

selectively removing the remaining portion of the carbon film by using a selective etch process gas in a reactor chamber, so that an overlapped portion of the remaining structural element with the first predetermined pattern is suspended above an underneath cavity above the substrates;

wherein after etching the discarded portion of the structural film and before selectively removing the remaining portion of the carbon film, the method further comprises one or multiple cycles of orderly film deposition and patterning process steps comprising;

depositing a topping film comprising a single or multiple layers of solid state materials conformed to and adherent to the substrate and the remaining structural element;

photolithographically defining a predetermined topping film pattern in the topping film, wherein the predetermined topping film pattern is determined on the substrate and the remaining structural element of the structural film; and

etching a remaining portion of the topping film outside the predetermined topping film pattern, wherein the remaining portion of the carbon film is not fully enclosed by the predetermined topping film pattern so that part of the remaining portion of the carbon film still remains exposed on its top surface and/or its sidewalls, and a spatial open channel is formed in the structural film for selective removal of the remaining portion of the carbon film so as to create another alternative suspended MEMS microstructure including both the remaining structural element and the remaining portion of the topping film outside the predetermined topping film pattern above the cavity on the substrate.

2. The method according to claim 1 wherein the selective etch process gas consists of oxygen in the reactor chamber containing plasma generated with a plasma source power.

3. The method according to claim 1 wherein the selective etch process gas consists of nitrogen in the reactor chamber containing plasma generated with a plasma source power.

4. The method according to claim 1 wherein the carbon film is deposited by means of:

placing the substrate in a reactor chamber;

introducing a carbon-containing process gas into the chamber and introducing a layer-enhancing additive gas that enhances thermal properties of the carbon film;

generating a reentrant toroidal RF plasma current in a reentrant path that includes a process zone overlying the substrate by coupling a plasma RF source power to an external portion of the reentrant path; and

coupling RF plasma bias power or bias voltage to the substrate.

5. The method according to claim 1 wherein the carbon film comprises less than 9 percent of hydrogen.

6. The method according to claim 1 wherein the substrate comprises layers selected from among solid state semiconductor, dielectric and conductor materials.

7. The method according to claim 1 wherein after etching the unwanted portion of the carbon film and before depositing the structural film, the method further comprises etching the substrate which is a semiconductor substrate by using the remaining portion of the carbon film as a hard mask.

8. The method according to claim 1 wherein after etching the discarded portion of the structural film and before selectively removing the remaining portion of the carbon film, the method further comprises selectively etching the substrate which is a semiconductor substrate by using both the remaining structural element and the remaining portion of the carbon film as a joint hard mask.

9. The method according to claim 1 wherein the topping film comprises layers selected from polycrystalline silicon, amorphous silicon, single-crystal silicon, silicon dioxide, silicon nitride, silicon carbide, organosilicate glass, tungsten, tungsten nitride, tungsten carbide, elemental aluminum and aluminum alloys, aluminum oxide, aluminum nitride, aluminum carbide, elemental tantalum and tantalum alloys, tantalum oxide, elemental titanium and titanium alloys, titanium nitride, titanium oxide, elemental copper and copper alloys, copper oxide, vanadium and vanadium oxide.