Etching gas

Abstract

The present invention provides an etching gas containing 1,1,1,2-tetrafluoroethane and a fluorocarbon-based compound having one or more double bonds.

Description

Etching gas

[0001] The present disclosure relates to an etching gas comprising 1,1,1,2-tetrafluoroethane.

[0002] 1,1,1,2-tetrafluoroethane is known as an etching gas.

[0003] Reactive Plasma Etching of SiC in a Tetrafluoroethane / Oxygen Plasma American Physical Society, Texas Section Fall, October 23-25, 2003, Texas Tech Campus, Lubbock Texas, MEETING ID: TSF03, abstract id. A5.008October 2003

[0004] Although 1,1,1,2-tetrafluoroethane is known as an etching gas, the inventors have discovered that it causes side etching, which makes it difficult to obtain a desired processed shape.

[0005] An object of the present disclosure is to provide an etching gas containing 1,1,1,2-tetrafluoroethane that is less likely to cause side etching.

[0006] The present disclosure includes the following aspects. [Item 1] An etching gas containing 1,1,1,2-tetrafluoroethane and a fluorocarbon-based compound having one or more double bonds. [Item 2] The etching gas according to Item 1, wherein the fluorocarbon-based compound having a double bond has one double bond. [Item 3] The etching gas according to Item 1 or 2, wherein the fluorocarbon-based compound having a double bond has two or three carbon atoms. [Item 4] The etching gas according to any one of Items 1 to 3, wherein the fluorocarbon-based compound having a double bond includes at least one compound selected from the group consisting of 1-chloro-1,2-difluoroethene, 1-chloro-1-fluoroethene, and 3,3,3-trifluoropropene. [Item 5] The etching gas according to any one of Items 1 to 4, wherein the concentration of the fluorocarbon-based compound having one or more double bonds relative to the total of 1,1,1,2-tetrafluoroethane and the fluorocarbon-based compound having one or more double bonds is 1 ppm by volume or more and less than 400 ppm by volume. [Item 6] The etching gas according to any one of Items 1 to 5, wherein the concentration of the fluorocarbon compound having one or more double bonds relative to the total of 1,1,1,2-tetrafluoroethane and the fluorocarbon compound having one or more double bonds is 50 ppm by volume to 300 ppm by volume. [Item 7] The etching gas according to any one of Items 1 to 6, further comprising an inert gas. [Item 8] The etching gas according to Item 7, wherein the inert gas is argon. [Item 9] The etching gas according to any one of Items 1 to 8, wherein the concentration of 1,1,1,2-tetrafluoroethane in the etching gas is 1.0% by volume to 20% by volume.

[0007] The etching gas of the present disclosure suppresses side etching.

[0008] FIG. 1 is a schematic diagram for explaining the side etching rate.

[0009] The etching gas of the present disclosure includes 1,1,1,2-tetrafluoroethane, a fluorocarbon-based compound having one or more double bonds, and an inert gas.

[0010] The mixed gas containing 1,1,1,2-tetrafluoroethane contains a fluorocarbon compound having one or more double bonds, and thus can suppress side etching during etching, particularly during hole etching.

[0011] The fluorocarbon compound having a double bond is typically a hydrofluoroolefin (HFO).

[0012] Examples of hydrofluoroolefins (HFOs) include 2-chloro-1,1-difluoroethene (HFO-1122), (E / Z)1-chloro-1,2-difluoroethene (HFO-1122a), trifluoroethene (HFO-1123), 1-chloro-2-fluoroethene (HFO-1131), 2,3,3,3-tetrafluoropropene (HFO-1234yf), 3,3,3-trifluoropropene (HFO-1243zf), trans-1,3,3,3-tetrafluoropropene (HFO-1234ze), 1,3,3,3-tetrafluoropropene (HFO-1234zd), and 1,2,3,3,3-pentafluoropropene (HFO-1336mzz).

[0013] In one embodiment, the fluorocarbon compound having a double bond has one double bond.

[0014] In one embodiment, the fluorocarbon compound having a double bond has 2 or 3 carbon atoms.

[0015] In a preferred embodiment, the fluorocarbon compound having a double bond includes at least one compound selected from the group consisting of 1-chloro-1,2-difluoroethene, 1-chloro-2-fluoroethene, and 3,3,3-trifluoropropene. The fluorocarbon compound having a double bond is preferably 1-chloro-1,2-difluoroethene, 1-chloro-2-fluoroethene, or 3,3,3-trifluoropropene. The fluorocarbon compound having a double bond may be used alone or in combination of two or more types.

[0016] The concentration of the fluorocarbon compound having a double bond relative to the total of 1,1,1,2-tetrafluoroethane and the fluorocarbon compound having one or more double bonds can be 1 ppm by volume or more, preferably 5 ppm by volume or more, more preferably 10 ppm by volume or more, and even more preferably 50 ppm by volume or more, for example, 100 ppm by volume or more. By including 1 ppm by volume or more of the fluorocarbon compound having a double bond, side etching is suppressed. Furthermore, the concentration of the fluorocarbon compound having a double bond can be less than 500 ppm by volume, preferably 400 ppm by volume or less, more preferably 300 ppm by volume or less, for example, 200 ppm by volume or less, or 100 ppm by volume or less. By setting the concentration of the fluorocarbon compound having a double bond to less than 500 ppm by volume, clogging of holes during etching can be suppressed. The concentration of the fluorocarbon compound having a double bond may be less than 1 ppm by volume or more and less than 500 ppm by volume, preferably 5 to 400 ppm by volume, and more preferably 50 to 300 ppm by volume.

[0017] The etching gas of the present disclosure may contain an inert gas, which is used as a so-called dilution gas.

[0018] The inert gas is not particularly limited as long as it is a gas inert to 1,1,1,2-tetrafluoroethane and fluorocarbon compounds having double bonds. The inert gas is, for example, nitrogen or a rare gas. The rare gas is helium, neon, argon, xenon, or krypton. The inert gas is preferably argon. The inert gas may be used alone or in combination of two or more kinds.

[0019] The etching gas of the present disclosure may include an additive gas.

[0020] Examples of the additive gas include oxygen and hydrogen.

[0021] The concentration of oxygen in the etching gas may be, for example, 1.0 to 20% by volume, preferably 2.0 to 10% by volume, and more preferably 2.0 to 5.0% by volume. Preferably, oxygen is used in an amount of 50 to 150% of the amount of 1,1,1,2-tetrafluoroethane, more preferably 80 to 120% of the amount of 1,1,1,2-tetrafluoroethane, for example, the same amount.

[0022] The concentration of hydrogen in the etching gas may be, for example, 0.1 to 10% by volume, preferably 0.1 to 1.0% by volume, and more preferably 0.1 to 0.50% by volume. Preferably, hydrogen is used in an amount of 10 to 20% of the amount of 1,1,1,2-tetrafluoroethane.

[0023] The concentration of 1,1,1,2-tetrafluoroethane in the etching gas is preferably 1.0 to 20% by volume, more preferably 1.0 to 20% by volume.

[0024] The etching gas of the present disclosure is preferably used for dry etching.

[0025] The etching gas of the present disclosure can etch various substrates. ２ , SiN, etc.

[0026] (Etching Method) Etching using the etching gas of the present disclosure can be performed by a conventional etching method, preferably a dry etching method. The etching conditions can be, for example, the following: Flow rate: 5 to 500 sccm, preferably 10 to 300 sccm; Discharge power: 200 to 1000 W, preferably 300 to 600 W; Bias power: 10 to 2000 W, preferably 100 to 1000 W; Pressure (gauge pressure): 30 mTorr or less (3.99 Pa or less), preferably 2 to 10 mTorr (0.266 to 1.33 Pa); Electron density: 10 ９ ~10 １３ cm －３ , preferably 10 １０ ~10 １２ cm －３Electron temperature: 2 to 9 eV, preferably 3 to 8 eV; Wafer temperature: -40 to 100°C, preferably -30 to 50°C; Chamber wall temperature: -30 to 300°C, preferably 20 to 200°C.

[0027] The etching gas of the present disclosure will be described in more detail below through the following examples, but the present disclosure is not limited to these examples.

[0028] Mixed gases of 1,1,1,2-tetrafluoroethane and fluorocarbon compounds containing the fluorocarbon compounds in the amounts shown in the table below were prepared. The fluorocarbon compounds used were 1-chloro-1,2-difluoroethene (HFO-1122a), 1-chloro-2-fluoroethene (HFO-1131), and 3,3,3-trifluoropropene (HFO-1243zf). Mixed gas 0 contained only 1,1,1,2-tetrafluoroethane and no fluorocarbon compounds.

[0029]

[0030] Using the above mixed gases 1 to 12 and the reference gas, the SiO ２ and SiN films were etched. Specifically, after introducing the mixed gas and additive gas through a gas inlet connected to the upper electrode, etching was performed by exciting the process gas with a high-frequency power source (13.56 MHz, 0.22 W). The film thickness was 100 μm. The flow rates of each gas are shown in the table below.

[0031] After etching, the edge of the silicon wafer was observed with an SEM to determine the side etch rate. The relative ratio of the side etch rate to the comparative example is shown in the table below. The side etch rate R is the ratio of the side etch amount a to the diameter b of the hole shown in Figure 1, and is calculated by the following formula: R = a / b

[0032]

[0033] The etching gas of the present disclosure is suitable for use in fields requiring more precise etching, such as the semiconductor field.

Claims

1. An etching gas containing 1,1,1,2-tetrafluoroethane and a fluorocarbon compound having one or more double bonds.

2. The etching gas according to claim 1, wherein the fluorocarbon compound having a double bond has one double bond.

3. The etching gas according to claim 1 or 2, wherein the fluorocarbon compound having a double bond has two or three carbon atoms.

4. The etching gas according to any one of claims 1 to 3, wherein the fluorocarbon compound having a double bond includes at least one compound selected from the group consisting of 1-chloro-1,2-difluoroethene, 1-chloro-1-fluoroethene, and 3,3,3-trifluoropropene.

5. The etching gas according to any one of claims 1 to 4, wherein the concentration of the fluorocarbon compound having one or more double bonds relative to the total of 1,1,1,2-tetrafluoroethane and the fluorocarbon compound having one or more double bonds is 1 ppm by volume or more and less than 400 ppm by volume.

6. The etching gas according to any one of claims 1 to 5, wherein the concentration of the fluorocarbon compound having one or more double bonds relative to the total of 1,1,1,2-tetrafluoroethane and the fluorocarbon compound having one or more double bonds is 50 ppm by volume or more and 300 ppm by volume or less.

7. The etching gas according to any one of claims 1 to 6, further comprising an inert gas.

8. The etching gas according to claim 7, wherein the inert gas is argon.

9. The etching gas according to any one of claims 1 to 8, wherein the concentration of 1,1,1,2-tetrafluoroethane in the etching gas is 1.0% by volume or more and 20% by volume or less.

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