Control method of discharge plasma

Abstract

To provide a discharge plasma control method capable of maintaining plasma even under a high pressure by focusing it with a relatively low voltage.SOLUTION: The present invention provides a discharge plasma control method using a plasma vapor chemical growth device, comprising: a step of setting a predetermined substrate electrode into the plasma vapor chemical growth device; a step of exhausting the inside of the plasma vapor chemical growth device in vacuum; a step of irradiating the substrate electrode with ultraviolet light; a step of introducing a gas in a constant flow amount containing a fluorine compound or a rare gas into the plasma vapor chemical growth device; and a step of exhausting the gas in a direction that is the same direction where the gas is introduced, and increasing a pressure of the gas by reducing the exhaust amount of the gas.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for controlling a discharge plasma. [Background technology]

[0002] Integrated circuits using semiconductors (hereafter referred to as "semiconductors") have contributed to the miniaturization and high performance of electronic devices. In particular, the miniaturization of the semiconductor manufacturing process itself is one of the major factors in increasing functionality, as it makes it possible to load many transistors per unit area. In addition, the widespread use of high-performance electronic devices, including personal computers and smartphones, continues to drive demand for semiconductors.

[0003] Incidentally, in the semiconductor manufacturing process, chemical vapor deposition technology (hereinafter referred to as "plasma CVD"; see, for example, Patent Document 1) and etching technology utilizing discharge plasma (hereinafter referred to as plasma) are indispensable. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 3642385 Summary of the Invention [Problem to be solved by the invention]

[0005] Here, in conventional plasma CVD and etching under reduced pressure, the challenge is to significantly increase the supply of active species that react on the substrate surface. If the pressure of the atmospheric reaction gas is increased to promote the plasmatization of these gas molecules, the plasma can be made denser and the amount of active species can be increased, but this requires restrictions on the degree of freedom, such as the spacing between the device electrode pairs, and a high voltage of several thousand volts between the electrodes. Therefore, the inventors focused on the possibility of realizing high plasma density at low voltage by controlling the pressure and flow rate of the atmospheric reaction gas. [Means for solving the problem]

[0006] The present invention is a discharge plasma control method using a plasma vapor chemical growth apparatus, comprising the steps of: placing a predetermined substrate electrode in the plasma vapor chemical growth apparatus; evacuating the inside of the plasma vapor chemical growth apparatus; irradiating the substrate electrode with ultraviolet light; introducing a constant flow rate of gas containing a fluorine compound or a rare gas into the plasma vapor chemical growth apparatus; and exhausting the gas in the same direction as the gas was introduced, thereby increasing the pressure of the gas by reducing the amount of gas exhausted.

[0007] In addition to the above, the present invention is a discharge plasma control method, in which the flow rate of the gas is set to 25 sccm or more and the pressure is set to 300 Pa or more.

[0008] Furthermore, in addition to the above, the present invention is a discharge plasma control method, which sets the flow rate of the gas to 65 sccm or less and the pressure to 6500 Pa or less.

[0009] In addition to the above, the present invention provides a discharge plasma control method, wherein the plasma chemical vapor deposition apparatus includes a metal counter electrode on the ultraviolet light irradiation side, and the electrode distance between the substrate electrode and the metal counter electrode is approximately several tens of mm. Effect of the Invention

[0010] Therefore, according to the plasma control method of the present invention, by controlling the pressure and flow rate of the gas, it is possible to realize high density plasma at a low voltage and control the shape of the plasma. For example, it is possible to control high density and position-selective plasma that can be maintained even under pressures of 500 Pa or more.

[0011] The control method of the present invention enables the generation of high-density, position-selective plasma that can be focused and maintained at a relatively low voltage even under high pressure, enabling a maskless semiconductor manufacturing process that does not rely on mask techniques that regulate the area in advance using photolithography technology or the like. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram showing a plasma generating device of the present invention. [Diagram 2] 1 is a graph showing the relationship between plasma current density and Ar pressure under various conditions in the present invention. [Diagram 3] 1 is an image of plasma before focusing in the present invention. [Figure 4] 1 is an image of plasma in which focusing was observed in the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] A plasma generating device 10 used in the present invention shown in Fig. 1 will be described. The plasma generating device 10 is a plasma vapor phase chemical growth device that uses the photoelectric effect of ultraviolet light as an initial electron source, and includes a vacuum chamber 20, a variable gas line 21 for introducing gases including rare gases such as Ar and He and fluorine compounds such as SF6 and CF4, a gas control unit 22 for controlling the flow rate of the gases, a gas exhaust unit 23 for exhausting the gases, a UV lamp 24 for irradiating ultraviolet light into the vacuum chamber 20, a quartz window 25 that transmits the ultraviolet light, a substrate electrode 30 to be subjected to the treatment, an insulating cover 31 on the substrate electrode, and a metal counter electrode 40 made of a metal such as Cu. It should be noted that this generator is just one example, and similar effects can be obtained with other plasma generators.

[0014] The vacuum chamber 20 is made of stainless steel SUS or an alloy such as BeCu. The variable gas line 21 can control the pressure in the vacuum chamber 20 and can be adjusted to a minimum of 10 -6It is possible to lower the pressure to the order of Pa. The gas control unit 22 is attached to the variable gas line 21 and is capable of controlling the flow rate of the gas. The gas exhaust unit 23 is attached in parallel to the variable gas line 21.

[0015] The UV lamp 24 is a lamp that irradiates ultraviolet light, and an example of the UV lamp 24 is a dielectric barrier discharge xenon excimer lamp that can irradiate deep ultraviolet light in the vicinity of 170 nm. The UV lamp 24 is installed above the quartz window 25.

[0016] The substrate electrode 30 is a plate made of the target material, such as Si or Cu, with a thickness of 1 mm or less, and is placed at the bottom of the vacuum chamber 20. The area other than the area where plasma is to be generated is covered with an insulating cover 31 made of quartz or the like. In the examples of Figures 3 and 4, the opening where plasma is to be generated is a circle with a diameter (φ) of 16 mm. At this time, by applying a negative voltage to this substrate electrode, a positive voltage is applied to the metal counter electrode 40, forming a circuit.

[0017] The metal counter electrode 40 has a slat-like shape and is placed on the top of the vacuum chamber 20. This shape does not prevent the ultraviolet light irradiated from the UV lamp 24 located directly above from reaching the substrate electrode. Here, the distance between the metal counter electrode 40 and the substrate electrode 30 is set to 22 mm. In other words, the distance between the metal counter electrode 40 and the substrate electrode 30 may be approximately several tens of mm.

[0018] The substrate electrode 30 and the metal counter electrode 40 are not covered with an obstacle such as glass, and are disposed at a distance and position that does not impede the flow of gas present in the chamber.

[0019] Next, a method for controlling discharge plasma using the above-mentioned device will be described. This method includes the steps of placing the substrate electrode 30 in the vacuum chamber 20, evacuating the inside of the device using the variable gas line 21, irradiating ultraviolet light using the UV lamp 24, and introducing the gas using the variable gas line 21.

[0020] The present invention is characterized by having a procedure in which the flow rate of the gas introduced into the plasma generated in the above procedure is controlled using a gas control unit 22, the gas in the vacuum chamber 20 is exhausted in the same direction as the gas introduction procedure using a gas exhaust unit 23, the pressure of the rare gas is increased by reducing the amount of exhaust, and the pressure and flow rate of the gas are set to certain conditions, for example, 500 Pa or more and 60 sccm, thereby focusing the generated plasma.

[0021] By having a procedure for focusing the plasma, high density plasma can be maintained up to 1000 Pa or more. By increasing the density of the plasma through focusing and maintaining it up to high pressure, high density plasma can be generated easily and at a specific position.

[0022] The plasma generated by the present invention can be applied to CVD and etching used in semiconductor manufacturing processes, especially the latter, for deep etching with a large aspect ratio required in three-dimensional semiconductor manufacturing processes. EXAMPLES

[0023] Below, examples are given to explain the present invention in more detail, but the present invention is not limited to the examples described below, and it is possible to carry out the present invention by making modifications within the scope of the purpose of the former and latter embodiments.

[0024] Using the embodiment of the present invention, it was observed that plasma can be maintained under high pressure (FIG. 2). In FIG. 2, the vertical axis indicates the plasma current density, and the horizontal axis indicates the pressure of Ar, which is an example of the gas. In the present invention, as shown in FIG. 2(a), when the flow rate of Ar is set to 60 sccm and the voltage between the substrate electrode 30 and the metal counter electrode 40 is set to 300 V, the plasma current density rises sharply at an Ar pressure of 585 Pa, and the plasma is focused from the state shown in FIG. 3 to the state shown in FIG. 4. At higher pressures, the plasma current density is maintained up to a high pressure of 6430 Pa, which indicates that a proportional plasma intensity is maintained up to the same pressure. Similarly, as shown in FIG. 2(b), when the flow rate of Ar is set to 50 sccm and the voltage between the substrate electrode 30 and the metal counter electrode 40 is set to 300 V, the plasma current density rises sharply at an Ar pressure of 577 Pa, and the plasma is focused. Similarly, as shown in FIG. 2(c), when the flow rate of Ar is set to 25 sccm and the voltage between the substrate electrode 30 and the metal counter electrode 40 is set to 300 V, the plasma current density increases rapidly at an Ar pressure of 300 Pa, and the plasma is focused.

[0025] The current density in Fig. 2 is calculated based on the area of ​​the opening in the insulating cover 31. In this example, it is a circle with a diameter of 16 mm. By carrying out the method of the present invention, it is focused to a diameter of 2.6 mm as shown in Fig. 4. Taking into account the increase in the current value, it is estimated that the effective current density, i.e., the plasma intensity, will be 50 times or more higher. [Explanation of symbols]

[0026] 10: Plasma generator 20: Vacuum chamber 21: Variable gas line 22: Gas control section 23: Gas exhaust section 24: UV lamp 25: Quartz window 30: Substrate electrode 31: Insulation cover 40: Metal counter electrode

Claims

1. A discharge plasma control method using a plasma-enhanced chemical vapor deposition apparatus, comprising: placing a predetermined substrate electrode in the plasma-enhanced chemical vapor deposition apparatus; evacuating the plasma-enhanced chemical vapor deposition apparatus; irradiating the substrate electrode with ultraviolet light; introducing a constant flow rate of a gas containing a fluorine compound or a rare gas into the plasma chemical vapor deposition apparatus; a step of exhausting the gas in the same direction as the gas was introduced, thereby decreasing the amount of exhaust of the gas, thereby increasing the pressure of the gas; A discharge plasma control method comprising:

2. 2. The method for controlling discharge plasma according to claim 1, wherein the flow rate of the gas is set to 25 sccm or more and the pressure is set to 300 Pa or more.

3. 2. The method for controlling discharge plasma according to claim 1, wherein the flow rate of the gas is set to 65 sccm or less and the pressure is set to 6500 Pa or less.

4. The plasma chemical vapor deposition apparatus is provided with a metal counter electrode on the ultraviolet light irradiation side, 2. The method for controlling discharge plasma according to claim 1, wherein the electrode gap between the substrate electrode and the metal counter electrode is approximately several tens of mm.

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