Reduction of br2 and cl2 in semiconductor processes

Abstract

One or more embodiments described herein relate to a reduction system for decreasing Br2 and Cl2 in semiconductor processing. In the embodiments described herein, a semiconductor etching process is performed within a processing chamber. Subsequently, fluorinated greenhouse gas (F-GHG), HBr, and Cl2 gases exit the processing chamber and enter a plasma reactor. A reagent gas is transferred from a reagent gas transfer device to the plasma reactor to mix with the processing gases. Radio frequency (RF) power is applied to the plasma reactor, adding energy and "exciting" the gases in the processing chamber. When HBr is excited, it forms Br2. Br2 and Cl2 are corrosive and toxic. However, the addition of H2O in the plasma reactor terminates the emission of Br2 and Cl2 because H atoms recombine with Br and Cl atoms to form HBr and HCl. HBr and HCl are readily soluble in water and are removed by a wet scrubber.

Description

[Technical Field] The one or more embodiments described herein are generally related to a reduction system for semiconductor processing, and more specifically, to a reduction system for reducing Br2 and Cl2 in semiconductor processing. [Previous Technology] Processing gases used in semiconductor processing facilities include many compounds that must be reduced or disposed of before disposal due to regulatory requirements and environmental concerns. For example, fluorinated greenhouse gases (F-GHGs), such as CF4, SF6, C4F8, and CHF3, are frequently used in etching processes. Along with F-GHGs, processing gases such as HBr and Cl2 are often used to improve selectivity and reduce oxidative damage to the substrate surface during etching. Under energized conditions, HBr is known to balance H2 + Br2. The plasma in the processing chamber has sufficient energy to cause Br2 formation. Conventional depletion systems also have sufficient energy to cause Br2 formation. Br2 and Cl2 are corrosive and toxic, causing environmental problems. Br2 is liquid at room temperature and can accumulate in exhaust pipes under certain conditions. Furthermore, Br2 and Cl2 are not water-soluble, therefore they cannot be adequately depleted in wet scrubbers. Increased Br2 and Cl2 emissions, attributed to increased HBr and Cl2 flow during etching processes due to the use of larger substrates in semiconductor processing, are also causing problems. In addition, a reduction system is needed to reduce Br2 and Cl2 in semiconductor processing. [Summary of the Invention] The embodiments described herein relate to methods for reducing the volume of treated gases. In one embodiment, a method for reducing the volume of a processing gas includes the following steps: performing a semiconductor etching process in a processing chamber using a processing gas, the processing gas including a fluorinated greenhouse gas (F-GHG), HBr, and Cl2, wherein the processing gas is configured to flow out of the processing chamber into a plasma reactor; introducing a reagent gas from a reagent gas delivery system into the plasma reactor to react with the processing gas; and applying RF power to the plasma reactor; wherein the ratio of the reagent gas flow rate to the HBr flow rate is greater than 2:1. In another embodiment, a method for reducing the volume of a processing gas includes the following steps: performing a semiconductor etching process in a processing chamber using a processing gas, the processing gas including fluorinated greenhouse gas (F-GHG), HBr, and Cl2, wherein the processing gas is configured to flow out of the processing chamber into a plasma reactor; introducing a reagent gas from a reagent gas delivery system into the plasma reactor to react with the processing gas; and applying RF power to the plasma reactor; wherein the ratio of the reagent gas flow rate to the Br2 byproduct gas is greater than 8:1. The embodiments described herein relate to systems for reducing the volume of gases. In one embodiment, a processing system includes: a processing chamber; a plasma reactor located downstream of the processing chamber; a reagent gas transfer device located between the processing chamber and the plasma reactor; a vacuum pump located downstream of the plasma reactor; a wet scrubber located downstream of the vacuum pump; a passivation gas transfer device located between the plasma reactor and the vacuum pump; and a controller configured to receive information from the processing system and, when executed by a processor, perform operations including: performing semiconductor etching in the processing chamber using processing gases, the processing gases including fluorinated greenhouse gases (F-GHG), HBr, and Cl2, wherein the processing gases are configured to flow from the processing chamber into the plasma reactor; introducing water vapor (H2O) from the reagent gas transfer system into the plasma reactor to react with the processing gases; and applying RF power to the plasma reactor; wherein the H2O flow rate to HBr flow rate ratio is greater than 2:1; and the H2O flow rate to Br2 byproduct gas ratio is greater than 15:1.

Implementation Method

Claims

1. A method for reducing the volume of processing gases, comprising the steps of: performing a semiconductor etching process in a processing chamber using processing gases, the processing gases including fluorinated greenhouse gas (F-GHG), HBr gas, and Cl2 gas; allowing the processing gases to flow from the processing chamber into a plasma reactor; introducing reagent vapor from a reagent vapor transfer system into the plasma reactor to react with the processing gases; applying RF power to the plasma reactor, in which the processing gases are at least partially converted into a Br2 byproduct gas and the Br2 byproduct gas reacts with the reagent vapor to form HBr, wherein a reagent vapor flow rate is in a ratio to an HBr flow rate of the HBr gas in the processing chamber greater than 2:1; and introducing a passivation gas between the plasma reactor and a pump configured to pump the gas away from the plasma reactor.

2. The method as described in claim 1, wherein the ratio of the reagent vapor flow rate to the HBr flow rate is greater than 5:

1.

3. The method as described in claim 1, wherein the reagent vapor comprises water vapor (H2O).

4. The method as described in claim 1, wherein the reagent vapor comprises hydrogen (H) and oxygen (O) atoms.

5. The method as described in claim 4, wherein the amount of H and O atoms is greater than the amount of F-GHG.

6. The method as described in claim 4, wherein the amount of F-GHG is greater than the amount of H and O atoms.

7. The method as described in claim 1, wherein the amount of RF power is between about 2000 watts and about 4000 watts.

8. The method as described in claim 1, wherein the F-GHG comprises at least one of the following: CF4, SF6, C4F8, or CHF3.

9. The method as described in claim 1 further comprises the step of pumping the gas leaving the plasma reactor and the passivation gas to a wet scrubber.

10. The method as described in claim 9, wherein the wet scrubber is selected from the group consisting of: a bubble column, a packed bed column, and a scrubbing column.

11. A method for reducing the volume of processing gases, comprising the steps of: performing a semiconductor etching process in a processing chamber using processing gases, the processing gases including fluorinated greenhouse gases (F-GHG), HBr gas, and Cl2 gas; allowing the processing gases to flow from the processing chamber into a plasma reactor; introducing reagent vapor from a reagent vapor transfer system into the plasma reactor to react with the processing gases, wherein the Cl2 gas reacts with the reagent vapor to form HCl within the plasma reactor; applying RF power to the plasma reactor, thereby at least partially converting the processing gases into a Br2 byproduct gas within the plasma reactor; and introducing a passivation gas between the plasma reactor and a pump configured to pump the gas away from the plasma reactor.

12. The method as described in claim 11, wherein the ratio of the reagent vapor flow rate to the Br2 byproduct gas is greater than 15:

1.

13. The method as described in claim 11, wherein the reagent vapor comprises water vapor H2O.

14. The method as described in claim 11, wherein the reagent vapor comprises hydrogen (H) and oxygen (O) atoms.

15. The method as described in claim 14, wherein the amount of H and O atoms is greater than the amount of F-GHG.

16. The method as described in claim 14, wherein the amount of F-GHG is greater than the amount of H and O atoms.

17. The method as described in claim 11, wherein the amount of RF power is between about 2,000 watts and about 4,000 watts.

18. The method as described in claim 11, wherein the F-GHG comprises at least one of the following: CF4, SF6, C4F8, or CHF3.

19. The method as described in claim 11 further comprises the step of pumping gas leaving the plasma reactor to a wet scrubber.

20. The method as described in claim 19, wherein the wet scrubber is selected from the group consisting of: a bubble column, a packed bed column, and a scrubbing column.

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