METHODS FOR HIGH PRECISION ETCHING OF SUBSTRATES

• US 20160013063A1
• Filed: 07/02/2015
• Published: 01/14/2016
• Est. Priority Date: 07/10/2014
• Status: Active Grant

• Current Assignee: Tokyo Electron Limited
• Original Assignee: Tokyo Electron Limited
• Inventors: Ranjan, Alok, Wang, Mingmei, Ventzek, Peter L. G.
• Granted Patent: US 9,768,033 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H01J 37/32082 Radio frequency generated discharge H01J37/32357, H01J37/32366, H01J37/32394 and H01J37/32403 take precedence
• CPC Class Codes: H01J 37/32146 Amplitude modulation, includes pulsing
• CPC Class Codes: H01J 37/32192 Microwave generated discharge H01J37/32357, H01J37/32366, H01J37/32394, H01J37/32403 take precedence
• CPC Class Codes: H01J 37/32816 Pressure
• CPC Class Codes: H01L 21/30655 comprising alternated and repeated etching and passivation steps, e.g. Bosch process
• CPC Class Codes: H01L 21/31116 by dry-etching
• CPC Class Codes: H01L 21/32136 using plasmas

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.

Claims

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;

applying an alternating bias power to the gas mixture that alternates on and off in an asymmetrical manner over a period of time, the bias power comprising a magnitude of no more than 150 W at a driving frequency; and

varying concentration of the gas mixture over the period of time, the variation ranging between 0% and 100% by volume of the reactant gas.

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 less 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;

alternating between the first plasma and the second plasma in an asymmetrical manner over a period of time.

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.