Dry etching method

Patent metadata

Field	Value
Publication number	US-2016307765-A1
Application number	US-201615196284-A
Country	US
Kind code	A1
Filing date	Jun 29, 2016
Priority date	Oct 8, 2013
Publication date	Oct 20, 2016
Grant date	—

Abstract

A dry etching method for isotropically etching each of SiGe layers selectively relative to each of Si layers in a laminated film is provided. The laminated film can include Si layers and SiGe layers alternately and repeatedly laminated. Each of the SiGe layers can be plasma-etched with plasma generated by a pulse-modulated radio frequency power using NF 3 gas.

First claim

1 . A dry etching method for isotropically etching SiGe layers selectively relative to Si layers in a laminated film composed of the Si layers and SiGe layers alternately laminated, the method comprising a step of plasma-etching the SiGe layers with plasma generated by a pulse-modulated radio frequency power using NF 3 gas.

2 . The dry etching method according to claim 1 , further comprising the step of mixing the NF 3 gas with any one of O 2 gas, N 2 gas, CO 2 gas, and CO gas.

3 . The dry etching method according to claim 1 , further comprising the step of forming a groove having a predetermined depth on the laminated film with continuous plasma before the plasma-etching the SiGe layers with plasma generated by the pulse-modulated radio frequency power using NF 3 gas.

4 . The dry etching method according to claim 1 ,
wherein the duty ratio of the pulse-modulated radio frequency power is set with a value such as to increase a ratio of radicals to ions from 20% to a higher ratio.

5 . The dry etching method according to claim 1 ,
wherein a duty ratio of a pulse-modulated radio frequency power is set with a value such as to increase a ratio of radicals to ions to make byproducts attain a level capable of forming a re-deposition and disturbing the plasma-etching of SiGe layer during On-time of the pulse modulated radio frequency power.

6 . The dry etching method according to claim 1 ,
wherein a duty ratio of the pulse-modulated plasma radio frequency power is set with a value such as to increase a ratio of radicals to ions to make byproducts attain a level capable of forming a re-deposition and disturbing the plasma-etching of SiGe layer during On-time of the pulse modulated radio frequency power.

7 . The dry etching method according to claim 6 , wherein a duty ratio of pulse-modulation is 50% or less.

8 . The dry etching method according to claim 6 , wherein a duty ratio of the pulse-modulated radio frequency power is set according to correlation data between a selection rate of the SiGe layer etching relative to a selection rate of the Si layer etching and a duty ratio of the pulse-modulation, the correlation data being acquired in advance.

9 . The dry etching method according to claim 1 ,
wherein a radio frequency power applied to a sample stage on which a sample having the laminated film is mounted is 0 W.

10 . A dry etching method for isotropically etching SiGe layers selectively relative to Si layers in a laminated film composed of the Si layers and SiGe layers alternately laminated, the method comprising a step of plasma-etching the SiGe layers with a pulse-modulated plasma using a mixed gas comprising a NF 3 gas and a N 2 gas.

11 . The dry etching method according to claim 10 ,
wherein a duty ratio of the pulse-modulated plasma radio frequency power is set with a value such as to increase a ratio of radicals to ions to make byproducts attain a level capable of forming a re-deposition and disturbing the plasma-etching of SiGe layer during On-time of the pulse modulated radio frequency power.

12 . The dry etching method according to claim 10 ,
wherein a radio frequency power applied to a sample stage on which a sample having the laminated film is mounted is 0 W.

Assignees

• Hitachi High Tech Corp

Inventors

• Shen Ze
• Ono Tetsuo
• Yasunami Hisao

Classifications

• H10P14/3411

  Silicon, silicon germanium or germanium · CPC title

• H10P50/242 Primary

  of Group IV materials · CPC title

• H01J37/32201

  Generating means · CPC title

• H01J37/32192

  Microwave generated discharge (H01J37/32357, H01J37/32366, H01J37/32394, H01J37/32403 take precedence) · CPC title

• H01L21/3065 Primary

  Electricity · mapped topic