Etching method

Patent metadata

Field	Value
Publication number	US-9911617-B2
Application number	US-201615299169-A
Country	US
Kind code	B2
Filing date	Oct 20, 2016
Priority date	Dec 25, 2015
Publication date	Mar 6, 2018
Grant date	Mar 6, 2018

Abstract

The invention discloses a novel dry etching method, which comprises the following steps: forming a to-be-etched layer on a semiconductor substrate; forming a masking material on the to-be-etched layer; carrying out dry etching on the masking material and the to-be-etched layer; simultaneously carrying out lateral etching (parallel to the surface of the substrate) of a masking layer and longitudinal etching (vertical to the surface of the substrate) of the to-be-etched layer; and obtaining the inclination angle (the included angle between a slope surface and the surface of the substrate) of the corresponding etched slope surface by accurately controlling the speed ratio. The method can flexibly adjust the inclination angle of the etched slope surface within a large range (0-90 degrees), and especially has advantages in the field of the application with a small inclination angle (smaller than 20 degrees) of the etched slope surface in comparison with a conventional etching method.

First claim

We claim:

1. An etching method, comprising:
forming a layer to be etched on a semiconductor substrate layer;
forming a mask material on the layer to be etched;
dry etching the mask material and the layer to be etched;
in the dry etching process, adjusting the ratio of a lateral etching rate (ERB) to the mask material to a longitudinal etching rate (ERA) to the layer to be etched, according to c tan θ=ERB/ERA, wherein,
θ is the desired angle value of the inclination angle of the end face of the layer to be etched, the inclination angle is the angle between the end face of the layer to be etched after the dry etching and the surface of the semiconductor substrate layer.

2. A method of claim 1 , wherein, the mask material is a photoresist layer having a thickness of 100 nm-100 μm, or other mask material which is well known in field of semiconductor.

3. A method of claim 1 , wherein, the layer to be etched is a semiconductor layer.

4. A method of claim 3 , wherein, the layer to be etched is a metal layer.

5. A method of claim 4 , in the dry etching, the etching gas comprises SF 6 /CF 4 /O 2 .

6. A method of claim 5 , wherein, the SF 6 gas and the CF 4 gas are used to etch the metal layer, and the O 2 gas is used to etch the mask material.

7. A method of claim 6 , wherein, the metal layer is a molybdenum (Mo) layer, the ratio is 7:1.

8. A method of claim 7 , wherein, the dry etching is performed with an air pressure of 50-80 mT, an RF Bias of 100-800 W and an Up and down electrode RF power of 20-500 W.

9. A method of claim 7 , wherein, the dry etching is performed with the SF 6 gas having a flow rate of 10-200 sccm, the CF 4 gas having a flow rate of 5-100 sccm and the O 2 gas having a flow rate of 20-500 sccm.

10. A method of claim 8 , wherein, the dry etching is performed with the SF 6 gas having a flow rate of 10-200 sccm, the CF 4 gas having a flow rate of 5-100 sccm and the O 2 gas having a flow rate of 20-500 sccm.

11. A method of claim 6 , wherein, the metal layer is a tungsten (W) layer, the ratio is 10:1.

12. A method of claim 11 , wherein, the dry etching is performed with an air pressure of 3-60 mT, an RF Bias of 100-500 W and an Up and down electrode RF power of 30-200 W.

13. A method of claim 11 , wherein, the dry etching is performed with the SF 6 gas having a flow rate of 20-100 sccm, the CF 4 gas having a flow rate of 5-100 sccm and the O 2 gas having a flow rate of 20-200 sccm.

14. A method of claim 12 , wherein, the dry etching is performed with the SF 6 gas having a flow rate of 20-100 sccm, the CF 4 gas having a flow rate of 5-100 sccm and the O 2 gas having a flow rate of 20-200 sccm.

15. A method of claim 1 , wherein, θ is smaller than 20 degrees.

Assignees

• Inst Of Microelectronics Cas

Inventors

• Li Junjie
• Li Junfeng
• Yang Qinghua
• Liu Jinbiao
• He Xiaobin

Classifications

• H10P50/694

  characterised by their behaviour during the process, e.g. soluble masks or redeposited masks · CPC title

• H10P50/267

  using plasmas · CPC title

• H10P50/71

  using masks for conductive or resistive materials · CPC title

• H10P50/242 Primary

  of Group IV materials · CPC title

• H10P50/693

  characterised by their size, orientation, disposition, behaviour or shape, in horizontal or vertical plane · CPC title