Method for manufacturing passivation film

Abstract

To provide a method for manufacturing a passivation film by which the passivation film having low concentration of oxygen atoms can be manufactured with good reproducibility.SOLUTION: A passivation film is manufactured by a method including a passivation step of processing a substrate having at least one of germanium and molybdenum on a surface by a passivation gas containing an oxygen-containing compound that is a compound having an oxygen atom in a molecule and hydrogen sulfide to form a passivation film containing a sulfur atom on a surface of the substrate. Concentration of an oxygen-containing compound in the passivation gas is 0.001 molar ppm or more and less than 75 molar ppm.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a passivation film.

Background Art

[0002] In recent years, in the semiconductor field, semiconductor materials containing elements other than silicon (Si) have attracted attention. Examples of semiconductor materials containing elements other than silicon include semiconductor materials containing group III-V elements such as germanium (Ge) and indium gallium arsenide (InGaAs), and semiconductor materials containing metal chalcogenides such as molybdenum(IV) sulfide (MoS2). Although these semiconductor materials have the advantage of high mobility compared to silicon materials, there are cases where film formation is difficult or mobility decreases due to a high defect density at the interface between materials.

[0003] Therefore, in order to reduce the defect density at the interface between materials, a method of forming a passivation film using hydrogen sulfide (H2S) gas on a substrate such as germanium or molybdenum has been proposed (see, for example, Patent Document 1). Further, as a method for forming a metal chalcogenide film, a method of treating a molybdenum oxide layer or a tungsten oxide layer with hydrogen sulfide gas to form a molybdenum sulfide layer or a tungsten sulfide layer has been proposed (see, for example, Patent Document 2).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, depending on the quality of the hydrogen sulfide gas, the concentration of oxygen atoms contained in the passivation film may increase, and the performance of the passivation film may deteriorate. An object of the present invention is to provide a method for manufacturing a passivation film capable of reproducibly manufacturing a passivation film having a low concentration of oxygen atoms.

Means for Solving the Problems

[0006] To solve the above problems, one aspect of the present invention is as follows [1] to [5]. [1] A substrate having at least one of germanium and molybdenum on its surface is treated with a passivation gas containing an oxygen-containing compound, which is a compound having an oxygen atom in its molecule, and hydrogen sulfide, to form a passivation film containing sulfur atoms on the surface of the substrate. A passivation step is provided, A method for manufacturing a passivation film, wherein the concentration of the oxygen-containing compound in the passivation gas is 0.001 mol ppm or more and less than 75 mol ppm.

[0007] [2] The method for manufacturing a passivation film according to [1], wherein the concentration of the oxygen-containing compound in the passivation gas is 0.5 mol ppm or more and 65 mol ppm or less. [3] The method for manufacturing a passivation film according to [1] or [2], wherein the oxygen-containing compound is at least one of oxygen gas and water. [4] The method for manufacturing a passivation film according to any one of [1] to [3], wherein the substrate has a film containing at least one of germanium and molybdenum on its surface. [5] The method for manufacturing a passivation film according to any one of [1] to [4], wherein the substrate is treated with the passivation gas under the conditions of a temperature of 20°C or higher and 1500°C or lower and a pressure of 1 Pa or higher and 101 kPa or lower.

Effects of the Invention

[0008] According to the present invention, it is possible to reproducibly manufacture a passivation film having a low concentration of oxygen atoms.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0010] An embodiment of the present invention will be described below. Note that this embodiment shows an example of the present invention, and the present invention is not limited to this embodiment. Also, various changes or improvements can be made to this embodiment, and forms with such changes or improvements can also be included in the present invention.

[0011] The method for manufacturing a passivation film according to this embodiment includes a passivation step of treating a substrate having at least one of germanium and molybdenum on its surface with a passivation gas containing an oxygen-containing compound, which is a compound having an oxygen atom in the molecule, and hydrogen sulfide, to form a passivation film containing sulfur atoms on the surface of the substrate. And the concentration of the oxygen-containing compound in the passivation gas is 0.001 mol ppm or more and less than 75 mol ppm.

[0012] According to the method for manufacturing a passivation film according to this embodiment, it is possible to suppress the generation of an unintended oxide film and generate a stable sulfide film, so that it is possible to reproducibly manufacture a passivation film with a low concentration of oxygen atoms. In order to sufficiently suppress the formation of an unintentional oxide film and reproducibly produce a passivation film with a low oxygen atom concentration, the concentration of the oxygen-containing compound in the passivation gas needs to be 0.001 mol ppm or more and less than 75 mol ppm. However, the upper limit is preferably 65 mol ppm or less, more preferably 40 mol ppm or less, still more preferably 5 mol ppm or less, and the lower limit may be 0.5 mol ppm or more. Note that the lower the concentration of the oxygen-containing compound in the passivation gas, the better. However, a concentration lower than 0.001 mol ppm is difficult to measure.

[0013] The type of the oxygen-containing compound is not particularly limited. For example, oxygen gas (O2), water (H2O), carbon monoxide (CO), carbon dioxide (CO2), carbonyl sulfide (COS), and sulfur dioxide (SO2) can be mentioned. Among these oxygen-containing compounds, at least one of oxygen gas and water is preferable.

[0014] The substrate to be treated with the passivation gas is a substrate having at least one of germanium and molybdenum on its surface. However, the form in which the surface of the substrate has at least one of germanium and molybdenum is not particularly limited. For example, the substrate may have a film containing at least one of germanium and molybdenum on its surface.

[0015] In addition, the substrate having a film containing at least one of germanium and molybdenum on its surface may be any substrate as long as the film contains at least one of germanium and molybdenum. For example, a substrate used for forming a semiconductor element is suitable. In particular, a single-crystalline silicon substrate on which a film containing at least one of germanium and molybdenum is formed on the surface by physical vapor deposition (PVD) or chemical vapor deposition (CVD) is preferable.

[0016] The concentration of hydrogen sulfide in the passivation gas is not particularly limited as long as it is an amount sufficient for forming the passivation film, but it is preferably 1% by volume or more, more preferably 2% by volume or more, even more preferably 10% by volume or more, and particularly preferably 100% by volume. Among the components contained in the passivation gas, components other than hydrogen sulfide and oxygen-containing compounds are not particularly limited, and examples thereof include inert gases such as nitrogen gas and argon gas.

[0017] The pressure when treating the substrate with the passivation gas in the passivation process (for example, the pressure in the chamber where the treatment with the passivation gas is performed) is not particularly limited, but it is preferably 1 Pa or more and 101 kPa or less, more preferably 10 Pa or more and 90 kPa or less, and even more preferably 100 Pa or more and 80 kPa or less.

[0018] Also, the temperature when treating the substrate with the passivation gas in the passivation process (for example, the temperature of the substrate arranged in the chamber) is not particularly limited, but in order to obtain high in-plane uniformity of the treatment of the substrate surface with the passivation gas, it is preferably 20°C or more and 1500°C or less, more preferably 50°C or more and 1200°C or less, and even more preferably 100°C or more and 1000°C or less.

[0019] Furthermore, the length of the time for treating the substrate with the passivation gas in the passivation process is not particularly limited, but in consideration of the efficiency of the semiconductor device manufacturing process, it is preferably within 120 minutes. The time for treating the substrate with the passivation gas refers to the time from when the passivation gas is supplied to the chamber containing the substrate until the passivation gas in the chamber is exhausted by a vacuum pump or the like to finish the treatment of the substrate surface with the passivation gas.

[0020] The method for manufacturing a passivation film according to this embodiment can be suitably applied to a semiconductor film-forming apparatus for forming a passivation film on the surface of a substrate. The structure of this film-forming apparatus is not particularly limited, and the positional relationship between the substrate accommodated in the chamber, which is a reaction vessel, and the pipe connected to the chamber is also not particularly limited.

Examples

[0021] Examples and comparative examples are shown below to explain the present invention in more detail. (Example 1) Using the film-forming apparatus 1 shown in FIG. 1, a passivation film was formed on the surface of a substrate. The film-forming apparatus 1 includes a chamber 10 that performs a passivation process, and a temperature adjustment device (not shown) that adjusts the temperature inside the chamber 10. Inside the chamber 10, a stage 11 for supporting a sample 20 is provided. As the sample 20, a silicon substrate on which a 150-nm-thick silicon oxide film was formed, and further a 80-nm-thick germanium film was formed thereon was used.

[0022] To the chamber 10, on its upstream side, a passivation gas supply pipe 12 for supplying a passivation gas containing an oxygen-containing compound and hydrogen sulfide to the chamber 10 and an inert gas supply pipe 13 for supplying an inert gas to the chamber 10 are connected via valves 32 and 33, respectively.

[0023] Also, to the chamber 10, on its downstream side, an exhaust pipe 15 for discharging the gas inside the chamber 10 to the outside is connected, and a vacuum pump 38 is connected to the downstream side of the exhaust pipe 15 via a valve 35. The pressure inside the chamber 10 is controlled by a pressure controller 37 that controls the valve 35.

[0024] Using such a film forming apparatus 1, a passivation process was performed. The sample 20 was placed on the stage 11, and after reducing the pressure in the chamber 10 to less than 10 Pa, the temperature in the chamber 10 was raised to 800 °C. Then, the valve 32 was opened, and a passivation gas was supplied into the chamber 10 from the passivation gas supply pipe 12 at a pressure of 101 kPa. This passivation gas is a mixed gas of oxygen gas and hydrogen sulfide gas, and the concentration of oxygen gas in the passivation gas is 60 mol ppm. The flow rate of the passivation gas at this time was 100 sccm, and the pressure in the chamber 10 when forming a passivation film on the surface of the sample 20 was 67 kPa. Note that sccm represents the flow rate (mL / min) at 0 °C and 101.3 kPa.

[0025] After introducing the passivation gas for 30 minutes and sulfiding the surface of the sample 20 and forming a passivation film under the conditions of a temperature of 800 °C and a pressure of 67 kPa, the introduction of the passivation gas was stopped. Then, the inside of the chamber 10 was evacuated with the vacuum pump 38, and nitrogen gas, which is an inert gas, was supplied into the chamber 10 from the inert gas supply pipe 13 to replace the inside of the chamber 10 with nitrogen gas. After that, the temperature in the chamber 10 was lowered to room temperature, and the sample 20 on which the passivation film was formed was taken out of the chamber 10.

[0026] (Example 2) A passivation film was formed on the surface of the substrate in the same manner as in Example 1, except that the concentration of oxygen gas in the passivation gas was 30 mol ppm. (Example 3) A passivation film was formed on the surface of the substrate in the same manner as in Example 1, except that the concentration of oxygen gas in the passivation gas was 3.8 mol ppm. (Example 4) A passivation film was formed on the surface of the substrate in the same manner as in Example 1, except that the concentration of oxygen gas in the passivation gas was 0.75 mol ppm.

[0027] (Comparative Example 1) A passivation film was formed on the surface of the substrate in the same manner as in Example 1, except that the concentration of oxygen gas in the passivation gas was set to 75 mol ppm. (Comparative Example 2) A passivation film was formed on the surface of the substrate in the same manner as in Example 1, except that the concentration of oxygen gas in the passivation gas was set to 150 mol ppm.

[0028] (Example 5) A passivation film was formed on the surface of the substrate in the same manner as in Example 1, except that a sample 20 having a 150-nm-thick silicon oxide film formed on a silicon substrate and a 80-nm-thick molybdenum film formed thereon was used. (Example 6) A passivation film was formed on the surface of the substrate in the same manner as in Example 5, except that the concentration of oxygen gas in the passivation gas was set to 30 mol ppm.

[0029] (Example 7) A passivation film was formed on the surface of the substrate in the same manner as in Example 5, except that the concentration of oxygen gas in the passivation gas was set to 3.8 mol ppm. (Example 8) A passivation film was formed on the surface of the substrate in the same manner as in Example 5, except that the concentration of oxygen gas in the passivation gas was set to 0.75 mol ppm.

[0030] (Comparative Example 3) A passivation film was formed on the surface of the substrate in the same manner as in Example 5, except that the concentration of oxygen gas in the passivation gas was set to 75 mol ppm. (Comparative Example 4) A passivation film was formed on the surface of the substrate in the same manner as in Example 5, except that the concentration of oxygen gas in the passivation gas was set to 150 mol ppm.

[0031] Samples 20 on which the passivation films of Examples 1 to 8 and Comparative Examples 1 to 4 were formed were analyzed by time-of-flight secondary ion mass spectrometry (TOF-SIMS: Time-of-Flight Secondary Ion Mass Spectrometry) to analyze the surface states of the germanium film or molybdenum film on which the passivation film was formed. The amounts of germanium oxide (GeOx), germanium sulfide (GeSx), molybdenum oxide (MoOx), and molybdenum sulfide (MoSx) in each passivation film are shown in the graphs of Tables 1, 2, and Figures 2 and 3.

[0032] [Table 1]

[0033] [Table 2]

[0034] As can be seen from the graphs of Tables 1, 2, and Figures 2 and 3, in Comparative Examples 1, 2, 3, and 4 where the concentration of oxygen gas in the passivation gas was 75 mol ppm or more, the ratio of the amount of oxide to the amount of sulfide in the passivation film of Sample 20 was large. On the other hand, in Examples 1 to 8 where the concentration of oxygen gas in the passivation gas was less than 75 mol ppm, the ratio of the amount of oxide to the amount of sulfide in the passivation film of Sample 20 was significantly smaller than that in the comparative examples, indicating that there is a critical condition between the examples and the comparative examples. Thus, it was shown that by treating with a passivation gas having a low concentration of oxygen gas, a sulfide film can be formed while suppressing the formation of an oxide film. [Explanation of Reference Numerals]

[0035] 1 ··· Film forming apparatus 10 ··· Chamber 11 ··· Stage 12 ··· Pipe for supplying passivation gas 13 ··· Pipe for supplying inert gas 15 ··· Exhaust pipe 20··· sample

Claims

1. A passivation step of treating a substrate having at least one of germanium and molybdenum on its surface with a passivation gas containing an oxygen-containing compound, which is a compound having an oxygen atom in the molecule, and hydrogen sulfide to form a passivation film containing sulfur atoms on the surface of the substrate is provided. A method for producing a passivation film, wherein the concentration of the oxygen-containing compound in the passivation gas is 0.001 mol ppm or more and less than 75 mol ppm.

2. The method for producing a passivation film according to claim 1, wherein the concentration of the oxygen-containing compound in the passivation gas is 0.5 mol ppm or more and 65 mol ppm or less.

3. The method for producing a passivation film according to claim 1 or claim 2, wherein the oxygen-containing compound is at least one of oxygen gas and water.

4. The method for producing a passivation film according to any one of claims 1 to 3, wherein the substrate has a film containing at least one of germanium and molybdenum on its surface.

5. The method for producing a passivation film according to any one of claims 1 to 4, wherein the substrate is treated with the passivation gas under the conditions of a temperature of 20 °C or more and 1500 °C or less and a pressure of 1 Pa or more and 101 kPa or less.

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