Etching method
The etching method using oxygen and sulfur-containing compounds enhances etching efficiency and pattern precision by suppressing shape abnormalities in carbon films, facilitating the formation of fine and precise etched features.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- DAIKIN INDUSTRIES LTD
- Filing Date
- 2024-12-25
- Publication Date
- 2026-07-07
Smart Images
Figure 2026112762000001 
Figure 2026112762000002 
Figure 2026112762000003
Abstract
Description
Technical Field
[0001] The present disclosure relates to an etching method.
Background Art
[0002] As a method for etching a carbon film, a plasma etching method using oxygen gas is known (Patent Document 1).
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] An object of the present disclosure is to provide a method for etching a carbon film more efficiently and suppressing shape abnormalities.
Means for Solving the Problems
[0005] The present disclosure includes the following aspects. [Item 1] An etching method for a carbon film, comprising: (1) Providing a substrate having a carbon film in a chamber (2) Etching the carbon film under plasma conditions using an etching gas containing oxygen and a reaction promoter, wherein in the etching gas, the partial pressure of oxygen is the largest, the reaction promoter contains S atoms, etching method. [Item 2] The etching method according to Item 1, wherein the reaction promoter is a compound containing 5% or more S atoms with respect to the total number of atoms. [Item 3]<The etching method according to claim 1 or 2, wherein the reaction accelerator is a compound containing 34% or more S atoms relative to the total number of atoms. [Section 4] The etching method according to any one of claims 1 to 3, wherein the reaction accelerator is a compound that does not contain oxygen atoms. [Section 5] The etching method according to any one of items 1 to 4, wherein the reaction accelerator is selected from the following compounds. TIFF2026112762000001.tif189162 TIFF2026112762000002.tif179157 [Section 6] The etching method according to any one of items 1 to 5, wherein the carbon film is a carbon film that serves as an etching mask in a subsequent process, is formed at a temperature of 300°C or higher, and may be doped with impurity atoms to increase etching resistance. [Section 7] The etching method according to any one of items 1 to 6, wherein the carbon film is an amorphous carbon film. [Section 8] The etching method according to any one of items 1 to 7, wherein the aspect ratio of the formed holes is 20 or greater. [Section 9] An etching method according to any one of items 1 to 8, wherein the diameter of the formed hole is φ160 nm or less. [Section 10] The etching method according to any one of items 1 to 9, wherein the diameter of the hole formed is φ80 nm or less. [Section 11] The etching method according to any one of items 1 to 10, wherein the substrate temperature in step (2) is -10°C or lower. [Section 12] The etching method according to any one of items 1 to 11, wherein the supply temperature of the etching gas in step (2) is in the temperature range of 200°C or less. [Section 13] The etching method according to any one of items 1 to 12, wherein the pressure inside the chamber in step (2) is 0.5 Pa to 15 Pa. [Item 14] The etching method according to any one of Items 1 to 13, wherein a bias voltage to be applied is applied in a pulsed manner to generate plasma. [Effect of the Invention]
[0006] According to the method of the present disclosure, in the etching of a carbon film, the etching rate is improved and etching can be performed efficiently. [Embodiment for Carrying out the Invention]
[0007] The etching method of the present disclosure is an etching method of a carbon film, and includes: (1) Providing a substrate having a carbon film in a chamber (2) Etching the carbon film under plasma conditions using an etching gas containing oxygen and a reaction accelerator. In the etching gas, the partial pressure of oxygen is the largest, and the reaction accelerator contains S atoms.
[0008] Step (1): Providing a substrate having a carbon film in a chamber
[0009] The substrate has a carbon film, and in the etching method of the present disclosure, such a carbon film is etched.
[0010] The carbon film is preferably an amorphous carbon film.
[0011] The carbon film is preferably a film formed at 300 °C or higher.
[0012] The carbon film may be doped with impurity atoms that increase etching resistance.
[0013] Examples of the impurity atoms include W, B, etc.
[0014] The content of impurity atoms in the carbon film described above may be, for example, 0 to 30% by mass, preferably 0 to 10% by mass, relative to the entire carbon film.
[0015] In one embodiment, the carbon film is doped with impurity atoms to increase etching resistance.
[0016] In one embodiment, the carbon film is not doped with impurity atoms to increase etching resistance.
[0017] The carbon film described above may exist on the substrate as a mask. For example, the carbon film can serve as an etching mask in a later process. Other layers, such as a silicon-containing film, may exist between the carbon film and the substrate.
[0018] The silicon-containing film described above may be a silicon oxide film or a silicon nitride film.
[0019] The carbon film may be masked. The mask is provided on the carbon film. The mask may be a metal-containing mask formed from a metal-containing material such as titanium nitride, tungsten, or tungsten carbide.
[0020] The mask on the carbon film described above is patterned; that is, the mask has a pattern that is transferred to the carbon film during the etching process.
[0021] The above-mentioned chamber provides a venue for performing etching. The chamber may be a general-purpose chamber typically used for etching, specifically a chamber for dry etching.
[0022] The size and material of the chamber are not particularly limited and can be appropriately selected according to the purpose.
[0023] Step (2) Etching the carbon film under plasma conditions using an etching gas containing oxygen and a reaction accelerator.
[0024] (Etching gas) The etching gas used in the etching method of this disclosure includes oxygen and a reaction accelerator.
[0025] In etching gases, the partial pressure of oxygen is the highest; that is, the concentration of oxygen is the highest.
[0026] In the etching gas, the oxygen concentration is preferably 50% by volume or more, more preferably 80% by volume or more, even more preferably 90% by volume or more, for example 95% by volume or more, 98% by volume or more, or 99% by volume or more. Alternatively, the oxygen concentration may be preferably 99.9% by volume or less, more preferably 99.8% by volume or less, for example 99.5% by volume or less, or 99% by volume or less.
[0027] The above reaction accelerator is a compound that promotes etching. The etching gas of this disclosure has an improved etching rate due to the inclusion of the reaction accelerator. Furthermore, it eliminates abnormalities in the shape of the formed patterns, such as grooves in wiring patterns and holes such as contact holes (e.g., bowing, distortion, twisting, etc.). It can be suppressed.
[0028] The reaction accelerator described above is preferably a compound containing a sulfur atom (S atom). By using a compound containing a sulfur atom, the etching rate can be improved and shape abnormalities can be suppressed.
[0029] The sulfur content in the above-mentioned sulfur-containing compound is preferably 5% or more, more preferably 10% or more, even more preferably 20% or more, even more preferably 30% or more, and particularly preferably 34% or more, for example, 40% or more or 45% or more, relative to the total number of atoms in the molecule. The upper limit of the sulfur content is not particularly limited, but may be, for example, 80% or less or 60% or less. The etching rate can be further improved by including a large amount of sulfur atoms.
[0030] The reaction accelerator described above preferably has an oxygen atom content of 20% or less, more preferably 10% or less, and even more preferably 5% or less, relative to the total number of atoms in the molecule, and is particularly preferably oxygen atom-free.
[0031] The sulfur atoms in the above reaction accelerator may be contained in the main chain of the molecule, or they may be contained in substituents of the main chain, for example, in a functional group. For example, the sulfur atoms may exist in the carbon main chain as -CSC-, -CSSC-, -C(=S)-, or -S(=O)-, or they may exist as =S at the molecular terminus. In addition, the sulfur atoms may exist as part of a functional group, for example, as -SH. R 1c It is a single bond.
[0032] Examples of compounds containing the above-mentioned sulfur atom include the following compounds. TIFF2026112762000003.tif189162 TIFF2026112762000004.tif179157
[0033] In a preferred embodiment, the compound containing the above-mentioned S atom may be COS or CS2.
[0034] The etching gas may be diluted with an inert gas as needed.
[0035] Examples of inert gases include noble gases and nitrogen. Examples of noble gases include helium, neon, argon, xenon, and krypton. These inert gases can be used individually or in combination of two or more. Furthermore, these inert gases can be known or commercially available.
[0036] When diluting etching gas with an inert gas, the amount of inert gas can be, for example, 0.1 to 10 volume percent of the total amount of etching gas.
[0037] The flow rate of the etching gas in step (2) is preferably 5 to 2000 sccm, more preferably 10 to 1000 sccm. If the etching gas is diluted with an inert gas, this flow rate is the flow rate of the mixture of the etching gas and the inert gas.
[0038] The supply temperature of the etching gas in step (2) is preferably 200°C or lower, more preferably 150°C or lower, and even more preferably 100°C or lower.
[0039] The substrate temperature in step (2) is preferably 50°C or lower, more preferably 30°C or lower, even more preferably 10°C or lower, even more preferably 0°C or lower, and particularly preferably -10°C or lower. The substrate temperature in step (2) may be, for example, -50°C or higher or -30°C or higher.
[0040] The pressure inside the chamber during process (2) is between 0.5 Pa and 15 Pa.
[0041] The discharge power in step (2) may preferably be 200 to 20,000 W, and more preferably 400 to 10,000 W.
[0042] The bias power in step (2) is preferably 25 to 15,000 W, more preferably 100 to 10,000 W.
[0043] The bias power in step (2) is preferably applied in a pulsed manner.
[0044] The electron density in step (2) is preferably 10 9 ~10 13 cm -3 , more 10 10 ~10 12 cm -3 It is possible.
[0045] The electron temperature in step (2) is preferably 2 to 9 eV, more preferably 3 to 8 eV.
[0046] Since the etching method of this disclosure can achieve a high etching rate, the patterns formed can be fine.
[0047] The aspect ratio of the pattern formed by the etching method of this disclosure may preferably be 20 or more, more preferably 30 or more, even more preferably 40 or more, and even more preferably 50 or more. The pattern is preferably a hole, particularly a contact hole. Here, the aspect ratio is the ratio of the depth to the width (or diameter) of the formed pattern.
[0048] The width or diameter of the pattern formed by the etching method of this disclosure may preferably be φ160 nm or less, more preferably φ120 nm or less, even more preferably φ80 nm or less, and even more preferably φ50 nm or less. The pattern is preferably a hole, particularly a contact hole. [Examples]
[0049] The present invention will be described in detail below using examples, but the present invention is not limited to these examples.
[0050] Examples 1-2 and Comparative Example 1 Each gas was introduced into an ICP (Inductively Coupled Plasma) plasma apparatus at the flow rates (sccm) shown in Table 1. The process pressure was maintained at 10 mTorr using a pressure regulating valve, and plasma was generated with a high-frequency power of 13.56 MHz and 900 W. A bias power of 400 kHz and 1000 W was applied to draw ions into the film to be etched. Etching was performed for 180 seconds at an ESC temperature (chuck temperature) of -10°C under the following conditions, and the etching rate (ER) was measured. A carbon film was used as the film to be etched. The results are shown in Table 1.
[0051] [Table 1]
[0052] Examples 3-4 and Comparative Example 2 Each gas was introduced into an ICP (Inductively Coupled Plasma) plasma apparatus at the flow rates (sccm) shown in Table 2. The process pressure was maintained at 10 mTorr using a pressure regulating valve, and plasma was generated with a high-frequency power of 13.56 MHz and 2100 W. A bias power of 400 kHz and 600 W was applied to draw ions into the film to be etched. Etching was performed for 180 seconds at an ESC temperature (chuck temperature) of -10°C under the following conditions, and the etching rate (ER) was measured. A carbon film patterned with a SiON film as an etching mask was used as the film to be etched. The results are shown in Table 2.
[0053] BowCD refers to the maximum width of the etched pattern, while topCD refers to the width of the pattern at the interface between the SiON mask and the carbon film.
[0054] [Table 2] [Industrial applicability]
[0055] The etching method of this disclosure is suitably used for etching substrates having a carbon film.
Claims
1. A method for etching a carbon film, (1) Provide a substrate having a carbon film inside the chamber. (2) Etching the carbon film under plasma conditions using an etching gas containing oxygen and a reaction accelerator. Includes, In the etching gas, the partial pressure of oxygen is the highest. The reaction accelerator contains an S atom, Etching method.
2. The etching method according to claim 1, wherein the reaction accelerator is a compound containing 5% or more sulfur atoms relative to the total number of atoms.
3. The etching method according to claim 1, wherein the reaction accelerator is a compound containing 34% or more sulfur atoms relative to the total number of atoms.
4. The etching method according to any one of claims 1 to 3, wherein the reaction accelerator is a compound that does not contain oxygen atoms.
5. The etching method according to claim 1, wherein the reaction accelerator is selected from the following compounds.
6. The etching method according to claim 1, wherein the carbon film is a carbon film that serves as an etching mask in a subsequent process, is formed at a temperature of 300°C or higher, and may be doped with impurity atoms to increase etching resistance.
7. The etching method according to claim 6, wherein the carbon film is an amorphous carbon film.
8. The etching method according to claim 1, wherein the aspect ratio of the formed holes is 20 or more.
9. The etching method according to claim 1, wherein the diameter of the formed holes is φ160 nm or less.
10. The etching method according to claim 1, wherein the diameter of the hole formed is φ80 nm or less.
11. The etching method according to claim 1, wherein the substrate temperature in step (2) is -10°C or lower.
12. The etching method according to claim 1, wherein the supply temperature of the etching gas in step (2) is in the temperature range of 200°C or less.
13. The etching method according to claim 1, wherein the pressure inside the chamber in step (2) is 0.5 Pa to 15 Pa.
14. The etching method according to claim 1, characterized in that the bias voltage applied to generate plasma is applied in a pulsed manner.