Method to remove metal and silicon oxide during gas-phase sacrificial oxide etch

• US 6,534,413 B1
• Filed: 10/27/2000
• Issued: 03/18/2003
• Est. Priority Date: 10/27/2000
• Status: Expired due to Fees

• Current Assignee: Air Products and Chemicals Incorporated (Linde Plc)
• Original Assignee: Air Products and Chemicals Incorporated (Linde Plc)
• Inventors: Robertson, Eric Anthony III, Beck, Scott Edward
• Primary Examiner(s): Utech, Benjamin L.
• Assistant Examiner(s): Brown, Charlotte A.
• Application Number:
  US09/698,467
• Time in Patent Office: 872 Days
• Field of Search: 438/706-711, 438/720, 438/723, 438/722
• US Class Current: 438/706
• CPC Class Codes: B81C 1/00936 Releasing the movable structure without liquid etchant
• CPC Class Codes: H01L 21/02049 with gaseous HF
• CPC Class Codes: H01L 21/31116 by dry-etching

Abstract

A method for removing sacrificial materials and metal contamination from silicon surfaces during the manufacturing of an integrated micromechanical device and a microelectronic device on a single chip is provided which includes the steps of adjusting the temperature of the chip using a reaction chamber to a temperature appropriate for the selection of a beta-diketone and the design of micromechanical and microelectronic devices, cycle purging the chamber using an inert gas to remove atmospheric gases and trace amounts of water, introducing HF and the beta-diketone as a reactive mixture into the reaction chamber which contains at least one substrate to be etched, flowing the reactive mixture over the substrate until the sacrificial materials and metal contamination have been substantially removed, stopping the flow of the reactive mixture; and cycle purging the chamber to remove residual reactive mixture and any remaining reaction by-products. Optionally, an oxidant gas may be added to the reactive mixture to promote the oxidation of metal species.

Claims

1. A method for removing sacrificial materials and metal contamination from silicon surfaces during the manufacturing of an integrated micromechanical device and a microelectronic device on a single chip, comprising the steps of:

(a) adjusting the temperature of the chip using a reaction chamber, as necessary, to a temperature appropriate for the beta-diketone employed in step (c) and the design of the micromechanical and microelectronic devices;

(b) cycle purging the chamber using an inert gas to remove atmospheric gases and trace amounts of water;

(c) introducing HF and the beta-diketone as a reactive mixture into the reaction chamber which contains at least one substrate to be etched;

(d) flowing the reactive mixture over the substrate until any sacrificial materials and metal contamination have been substantially removed;

(e) stopping the flow of the reactive mixture; and

(f) cycle purging the chamber to remove residual reactive mixture and any remaining reaction by-products.

2. The method for removing sacrificial materials and metal contamination of claim 1, wherein the inert gas is selected from the group consisting of nitrogen and argon.

3. The method for removing sacrificial materials and metal contamination of claim 1, including the step of adding a diluent to the reactive mixture.

4. The method for removing sacrificial materials and metal contamination of claim 3, wherein the step of adding the diluent includes adding a diluent selected from the group consisting of nitrogen, argon, helium, neon, xenon, krypton, and SF₆ to the mixture.

5. The method for removing sacrificial materials and metal contamination of claim 1, including the step of adding an oxidant gas to the reactive mixture to promote the oxidation of metal species.

6. The method for removing sacrificial materials and metal contamination of claim 5, wherein the step of adding the oxidant gas includes adding an oxidant gas selected from the group consisting of oxygen, chlorine, or nitrous oxide.

7. The method for removing sacrificial materials and metal contamination of claim 5, wherein the step of stopping the flow of the reactive mixture includes first stopping the oxidant flow to allow additional metal removal, while continuing to allow flow of the diluent.

8. The method for removing sacrificial materials and metal contamination of claim 1, wherein the step of cycle purging the chamber to remove residual reactive mixture and any remaining reaction by-products includes heating the substrate to help in the removal of the materials and contamination from less accessible areas of the silicon surfaces.

9. The method for removing sacrificial materials and metal contamination of claim 1, including the step of cycle purging the chamber while the reactive mixture is flowing to facilitate transport of the reactive mixture to active regions of the silicon surfaces and to facilitate removal of reaction by-products from the silicon surfaces.

10. The method for removing sacrificial materials and metal contamination of claim 1, wherein the step of introducing HF includes introducing anhydrous HF with not more than trace amounts of water present as contaminant.

11. The method for removing sacrificial materials and metal contamination of claim 1, wherein the beta-diketone is 2,2,6,6,-tetramethyl-3,5-heptanedione.

12. The method for removing sacrificial materials and metal contamination of claim 1, wherein the sacrificial materials are selected from the group consisting of silicon dioxide, silicon oxide, phosphorus and/or boron doped silicon dioxide and silicon oxynitrides.

13. The method for removing sacrificial materials and metal contamination of claim 1, wherein the sacrificial materials are metals.

14. The method for removing sacrificial materials and metal contamination of claim 7, where the oxidant flow is stopped sufficiently early in the process such that substantially no removal of metals from any structure of the micromechanical device occurs.

15. The method for removing sacrificial materials and metal contamination of claim 1, including the step of introducing and subsequently purging an oxidant gas into the reaction chamber prior to the step of introducing the reactive mixture.

16. In a process for the fabrication of a micro-electromechanical system which includes the step of providing a sacrificial layer of silicon oxide on a silicon surface, subsequently removing the sacrificial layer of silicon oxide and the removing of any metal contaminants from said silicon surface, the improvement which comprises:

effecting the simultaneous removal of said sacrificial layer of silicon oxide on said silicon surface and said removal of metal contaminates by contacting said silicon surface with a mixture of HF and a beta-diketone whereby said sacrificial layer is removed during the fabrication of said micro-electromechanical system.

17. The process of claim 16 wherein the beta-diketone is 2,2,6,6,-tetramethyl-3,5-heptanedione.