Methods for high precision etching of substrates

Patent metadata

Field	Value
Publication number	US-9768033-B2
Application number	US-201514790891-A
Country	US
Kind code	B2
Filing date	Jul 2, 2015
Priority date	Jul 10, 2014
Publication date	Sep 19, 2017
Grant date	Sep 19, 2017

Abstract

This disclosure relates to a plasma processing system and methods for high precision etching of microelectronic substrates. The system may include a combination of microwave and radio frequency (RF) power sources that may generate plasma conditions to remove monolayer(s). The system may generation a first plasma to form a thin adsorption layer on the surface of the microelectronic substrate. The adsorbed layer may be removed when the system transition to a second plasma. The differences between the first and second plasma may be include the ion energy proximate to the substrate. For example, the first plasma may have an ion energy of less than 20 eV and the second plasma may have an ion energy greater than 20 eV.

First claim

What is claimed is:

1. A method, comprising:
receiving a microelectronic substrate into a plasma process chamber;
receiving a gas mixture in the plasma process chamber, the gas mixture comprising a dilution gas and a reactant gas;
achieving a process pressure of greater than or equal to 40 mTorr in the plasma process chamber;
applying microwave power to the gas mixture to generate a plasma;
applying an alternating bias power to the gas mixture that alternates on and off in an asymmetrical manner over a period of time to provide a bias power cycle, the bias power comprising a magnitude of no more than 150 W at a driving frequency;
varying concentration of the gas mixture from a first concentration to a second concentration different from the first concentration over more than one consecutive bias power cycle, the first and second concentration each being between 0% and 100% by volume of the reactant gas
to transition said plasma between an adsorption state and etch state during a transition period.

2. The method of claim 1 , wherein the microwave power generates a plasma potential proximate to the substrate of less than or equal to 20 eV when the biasing is off.

3. The method of claim 2 , wherein the dilution gas comprises one or more of the following: argon, helium, or nitrogen, and the reactant gas comprises an oxygen-containing gas or a halogen-containing gas.

4. The method of claim 1 , wherein the driving frequency comprises a frequency less than 60 MhZ.

5. The method of claim 1 , wherein the reactant gas concentration varies between being greater than 10% by volume and being less than 10% by volume over the period of time.

6. The method of claim 1 , wherein the process pressure comprises a magnitude of no more than 500 mT.

7. The method of claim 1 , wherein the biasing power source is on between 300 ms and 5000 ms and is off for between 100 ms and 3000 ms during the period.

8. The method of claim 1 , wherein the biasing power comprises a magnitude between 10 W and 50 W or 100 W and 150 W.

9. The method of claim 1 , wherein the microwave power comprises a magnitude between 500 W to 3000 W and a driving frequency between 300 MhZ and 10 GHz.

10. The method of claim 9 , wherein the driving frequency comprises about 2.45 GHz.

11. A method for treating a substrate, comprising:
receiving the substrate into a process chamber comprising a substrate holder;
generating a first plasma using a first mixture of process gases in the process chamber, the first plasma comprising:
a radical-to-ion flux ratio (RIR) proximate to the substrate, the first RIR comprising a value of at least 100:1; and
a first ion energy proximate to the substrate, the first ion energy being less than 20 eV;

generating a second plasma using a second mixture of process gases in the process chamber, the second mixture being different from the first mixture, and the second plasma comprising
a second ion energy being higher than the first ion energy;

applying a plurality of bias cycles to said substrate holder, each bias cycle consisting of a bias voltage for an adsorption process and a bias voltage for a desorption process; and
alternating between the first plasma and the second plasma in an asymmetrical manner over a period of time by controlling the first and second gas mixtures to cause the first plasma to transition into the second plasma, and cause the second plasma to transition into the first plasma, each transition occurring over more than one bias cycle.

12. The method of claim 11 , wherein the generating of the first plasma comprises maintain a process pressure of greater than 40 mTorr in the process chamber.

13. The method of claim 11 , wherein the first plasma comprises a process time between 120 ms to 240 ms.

14. The method of claim 11 , wherein the first ion energy comprises a magnitude of less than 10 eV.

15. The method of claim 11 , wherein the second mixture of the process gas comprises a dilution gas and a halogen.

16. The method of claim 11 , wherein the first group of process gas comprise an oxygen-containing gas or a halogen-containing gas.

17. The method of claim 11 , wherein the alternating comprises applying a bias power to the substrate holder when generating the second plasma.

18. The method of claim 11 , wherein the second plasma comprises a process time up to 450 ms.

19. The method of claim 11 , wherein the first RIR comprises a value of up to 1000:1.

Assignees

• Tokyo Electron Ltd

Inventors

• Ranjan Alok
• Wang Mingmei
• Ventzek Peter L G

Classifications

• H10P50/283

  by chemical means · CPC title

• H10P50/244

  comprising alternated and repeated etching and passivation steps · CPC title

• H10P50/267 Primary

  using plasmas · CPC title

• H01J37/32816

  Pressure · CPC title

• H01J37/32082

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