Atomic layer etching of tantalum

• US 10,566,213 B2
• Filed: 07/30/2018
• Issued: 02/18/2020
• Est. Priority Date: 12/19/2016
• Status: Active Grant

• Current Assignee: Lam Research Corporation
• Original Assignee: Lam Research Corporation
• Inventors: Kanarik, Keren Jacobs, Kim, Taeseung
• Primary Examiner(s): Deo, Duy Vu N
• Application Number:
  US16/049,320
• Publication Number:
  US 20180350624A1
• Time in Patent Office: 568 Days
• CPC Class Codes: H01J 2237/2001 Maintaining constant desired temperature
• CPC Class Codes: H01J 2237/3341 Reactive etching
• CPC Class Codes: H01J 37/32715 Workpiece holder
• CPC Class Codes: H01J 37/32724 Temperature
• CPC Class Codes: H01L 21/02274 in the presence of a plasma [PECVD]
• CPC Class Codes: H01L 21/0228 deposition by cyclic CVD, e.g. ALD, ALE, pulsed CVD
• CPC Class Codes: H01L 21/30621 Vapour phase etching
• CPC Class Codes: H01L 21/3065 Plasma etching; Reactive-ion etching
• CPC Class Codes: H01L 21/31116 by dry-etching
• CPC Class Codes: H01L 21/31122 of layers not containing Si, e.g. PZT, Al2O3
• CPC Class Codes: H01L 21/32136 using plasmas
• CPC Class Codes: H01L 21/32138 pre- or post-treatments, e.g. anti-corrosion processes
• CPC Class Codes: H01L 21/67063 for etching
• CPC Class Codes: H01L 21/67069 for drying etching
• CPC Class Codes: H01L 21/67103 mainly by conduction
• CPC Class Codes: H01L 21/67207 comprising a chamber adapted to a particular process
• CPC Class Codes: H01L 21/67259 Position monitoring, e.g. misposition detection or presence detection
• CPC Class Codes: H01L 21/6831 using electrostatic chucks

Abstract

Methods for evaluating synergy of modification and removal operations for a wide variety of materials to determine process conditions for self-limiting etching by atomic layer etching are provided herein. Methods include determining the surface binding energy of the material, selecting a modification gas for the material where process conditions for modifying a surface of the material generate energy less than the modification energy and greater than the desorption energy, selecting a removal gas where process conditions for removing the modified surface generate energy greater than the desorption energy to remove the modified surface but less than the surface binding energy of the material to prevent sputtering, and calculating synergy to maximize the process window for atomic layer etching.

Claims

1. A method of etching tantalum on a substrate, the method comprising:

providing the substrate comprising tantalum;

cooling the substrate to a temperature less than about 0°

C.; and

performing atomic layer etching of the tantalum by;

exposing the substrate to a modification gas to modify a surface of the tantalum, the modification gas having a modification energy and a desorption energy with respect to the tantalum; and

exposing the modified surface to a removal gas and igniting a plasma to remove the modified surface of the tantalum;

wherein the modification energy is less than the desorption energy, and the desorption energy is less than a surface binding energy of the tantalum;

wherein an ion energy provided by the substrate temperature is between the modification energy and the desorption energy.

2. The method of claim 1, wherein the substrate is exposed to the modification gas at a substrate temperature less than about 0°

C.

3. The method of claim 1, wherein the temperature is between about −

20°

C. and about 0°

C.

4. The method of claim 1, wherein the substrate comprises a layer of tantalum.

5. The method of claim 1, wherein the substrate comprises tantalum nitride.

6. The method of claim 1, wherein the substrate comprises two or more layers of tantalum and/or tantalum nitride.

7. The method of claim 1, wherein the substrate temperature of less than about 0°

C. achieves self-limiting etching.