Ion-assisted deposition method, semiconductor manufacturing equipment component, and semiconductor manufacturing equipment

Abstract

To shorten an aging time by preparing a post-aging composition in advance, by depositing YOxFy on the surface of a high-frequency introduction window from the beginning in order to shorten then aging time.SOLUTION: After cleaning a substrate surface by irradiating the substrate for 30 minutes under the condition of Ar:O2=50:50 by using an ion gun, Y2O3 is subjected to electron-beam evaporation at a film deposition rate of 8.6Å / sec, and simultaneously 40 sccm oxygen gas and 2 sccm argon gas are sent into the ion gun, and oxygen ion is radiated onto the substrate under the condition of 1,000 V and 1,100 mA.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a composite structure in which a substrate surface is coated with a polycrystalline ceramic to impart functionality to the substrate. The present invention also relates to a semiconductor manufacturing apparatus and a display manufacturing apparatus equipped with the composite structure. In particular, the present invention relates to a composite structure with excellent particle resistance used in an environment exposed to corrosive plasma, such as a semiconductor manufacturing apparatus component, and a semiconductor manufacturing apparatus and a display manufacturing apparatus equipped with the composite structure. [Background technology]

[0002] Currently, semiconductor manufacturing processes involve etching silicon, silicon oxide films, silicon nitride films, and other materials using inductively coupled plasma etching equipment (hereafter referred to as ICP). The radio-frequency introduction window, which transmits radio-frequency waves, is typically formed by thermally spraying a Y2O3 film onto sintered alumina (Non-Patent Document 1) or by the AD method. Development of the IAD method (Non-Patent Document 2) has also begun. However, the surface of the radio-frequency introduction window is gradually fluorinated by fluorine plasma or fluorine radicals to form YOxFy, where the values of x and y are determined by the composition of the etching process gas used and saturate and stabilize at a certain value. Plasma discharge is continued until this surface fluorination value becomes constant, a process known as aging. If this surface does not stabilize, the deactivation of fluorine radicals within the chamber changes, resulting in an unstable etching rate. Aging can last as long as 70 hours. Furthermore, leaving the Y2O3 film as it is will cause oxygen deficiencies, and moisture will adhere to these deficiencies, leading to a deterioration in film quality. For this reason, baking at around 400°C was necessary immediately after film formation. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2020-012192 [Patent Document 2] Korean Patent Publication No. 2013-0145725 [Non-patent literature]

[0004] [Non-Patent Document 1] Journal of the Ceramic Society of Japan Vol.129 P.46 (2021) [Non-patent document 2] Journal of Applied Physics Vol.117, 014903 (2015) [Non-patent document 3] Jpn.J.Appl.Phys.Vol.57 06JF04 (2018) Summary of the Invention [Problem to be solved by the invention]

[0005] In the present invention, in order to shorten the aging time, a YOxFy film is formed on the surface of the high frequency introduction window from the beginning, and the composition after aging is kept in order, thereby shortening the aging time. Furthermore, the presence of YOF on the surface allows F to fill in oxygen vacancies, which has the effect of eliminating the need for baking immediately after film formation. [Means for solving the problem]

[0006] The substrate was cleaned by irradiating the substrate with an ion gun at a ratio of Ar:O2 = 50:50 for 30 minutes, and then Y2O3 was deposited by electron beam evaporation at a deposition rate of 8.6 Å / sec. At the same time, 40 sccm of oxygen gas and 2 sccm of argon gas were passed through the ion gun, and oxygen ions were irradiated onto the substrate at 1000 V and 1100 mA. [Effects of the Invention]

[0007] As a crystal, Y2O3 has a body-centered cubic structure. As shown in Figure 1, oxygen is located at each corner of the cube, with Y at the center. However, since Y is six-coordinated, two corners are devoid of oxygen. To neutralize this charge, Y is slightly shifted from the center and electrically neutralized. Conversely, because the two corners are vacant, oxygen can move relatively easily within the crystal.

[0008] In particular, the interface between crystal grains is energetically unstable, so oxygen easily escapes from the film. When fluorine is added, the crystal changes to an orthorhombic crystal. In an orthorhombic crystal, all vertices are filled with O and F. In other words, F is also useful for filling oxygen vacancies.

[0009] Furthermore, as shown in Figure 2, the equilibrium phase diagram for YO shows that only the form Y2O3 exists, but there is a high-temperature phase at 2295°C. This is an orthorhombic crystal. Furthermore, if the oxygen content is about 1% less, it becomes a cubic crystal.

[0010] In IAD, oxygen ions enter the film and impart energy by colliding with Y or O atoms, but since the mass of the oxygen atoms is smaller than that of the Y atoms, they are scattered far away.

[0011] Therefore, when oxygen ions stop and crystallize the surrounding area, it is thought that the surrounding area has little oxygen. In fact, the film formed by ion plating using plasma is transparent, but orthorhombic crystals are mixed in. This is because the oxygen ion energy is small and oxygen scattering in the film is small, so orthorhombic crystals are mixed in.

[0012] In our experiments, as the ion energy in IAD increases, the stress changes from tension to compression, and coloring begins at the same time. This corresponds to oxygen vacancies caused by oxygen ions. The crystal structure is body-centered cubic.

[0013] Further increase in ion irradiation results in the (111) preferential orientation, resulting in a re-close-packed surface. The final composition of YOxFy is determined by the surface condition after prolonged use in the etching process. In reality, fluorination occurs from the surface and diffuses into the interior.

[0014] That is, the composition of F is y at the surface, but decreases as it penetrates into the film. In areas that are hit by ions, such as directly below the coil of the ICP window of an etching device, the kinetic energy of the ions can cause a phase transition, potentially generating particles. Creating this state in advance through film formation leads to a reduction in aging time. The cross section of the film resembles the compositionally graded film of F.

[0015] The important thing here is to avoid YOF, i.e., O:F=1:1. Although many details about YOF are still unknown, it has been reported that YOF films are orthorhombic at room temperature, but undergo a phase transition and volume expansion between 500°C and 600°C, as shown in Figure 3 (Non-Patent Document 3). [Brief explanation of the drawings]

[0016] [Figure 1] Crystal structure of Y2O3 [Figure 2] Equilibrium phase diagram of YO [Figure 3] Phase transition of YOF [Figure 4] Schematic diagram of the IAD film deposition system [Figure 5] Y2O3 and YF3 deposition rates [Figure 6] Integrated film thickness of Y and O in Y2O3 and YF3 [Figure 7] Schematic diagram of a simplified etching device used in Example 3 [Figure 8] Etching rate ratio to cumulative etching time DETAILED DESCRIPTION OF THE INVENTION

[0017] A 25mm square, 2mm thick alumina substrate was mounted on a 600mm diameter SUS holder and set in the IAD device. After evacuation for 1 hour, it was heated to 300°C using a heater on the backside. Evacuation was continued in this state for 3 hours. A schematic diagram of the device is shown in Figure 4.

[0018] Two electron beam heated evaporation sources are installed, and the film thickness monitors are positioned opposite each other so that the evaporation material from each evaporation source can be seen. A filter with a 20% aperture ratio (not shown) is installed in front of the monitor. The ion gun is installed between the two evaporation sources. The test substrate for analysis is mounted on a holder carved out of alumina. The heater is wrapped around a stainless steel sheath heater and can heat up to 500°C. [Example]

[0019] Example 1 The experimental procedure is as follows: After 3 hours of evacuation, the vacuum level was 1.3 x 10-4 Pa. After that, an ion gun was used to irradiate the substrate with an ion current of 1000 V, 1100 mA for 30 minutes using Ar / oxygen = 50% / 50% at a total of 30 sccm, thereby cleaning the substrate surface.

[0020] Next, Y2O3 was deposited by electron beam evaporation at a film deposition rate of 8.6 Å / sec, and simultaneously oxygen ions were irradiated onto the substrate at 1000 V and 1100 mA with an ion gun supplying oxygen at 40 sccm and Ar at 2 sccm, with the distance between the deposition material surface and the substrate being 950 mm.

[0021] The substrate temperature was controlled at 300°C while being measured with an IR monitor to keep it constant during film formation. The film formation rate was monitored with a quartz crystal oscillator film thickness gauge and fed back to the output of the electron beam to stabilize the film formation rate. The holder was rotated during film formation to ensure uniform film thickness and uniform ion irradiation. The holder rotation was 10 rpm.

[0022] With a normal quartz crystal resonator film thickness gauge, the frequency deviation becomes large at thicknesses of 3 μm or more, making it impossible to make accurate measurements. The authors installed a filter plate with 1 mm diameter holes in a 1 mm thick SUS304 plate on the front of the monitor to achieve an aperture ratio of 20%, thereby limiting the amount of incident light and enabling measurements down to 10 μm.

[0023] In areas where ions are bombarded, such as directly below the coil of the ICP window of the etching equipment, the kinetic energy of the ions can cause a phase transition, potentially generating particles. After depositing a 9 μm Y2O3 film in this way, a 1 μm YF film was deposited. The Y2O3 deposition rate was gradually reduced to 4.2 / sec over one hour. The deposition rate was linearly reduced.

[0024] Meanwhile, YF3 was evaporated from another evaporation source and the deposition rate was increased linearly from 0 to 4.1 Å / sec over 1 hour. The total deposition rate remained almost constant, and only the O and F concentrations were gradually changed.

[0025] Figures 5 and 6 show the deposition rate and cumulative film thickness of Y2O3 and YF3. Composition analysis of the surface of this film using EDX revealed that Y:O = 1.53 at%, F = 0.47 at%. EDX measures approximately 0.2 μm in the depth direction, so more oxygen is detected than at the surface due to the cumulative effect. However, this method is sufficient to form a compositionally gradient film of YOxFy on the surface.

[0026] The cross section of this film was measured for oxygen and fluorine in the thickness direction from 9 μm to 10 μm using EDX. The etching rate ratio (ratio of F to Y) versus cumulative etching time for Y2O3 and Example 1 is shown in Figure 7. F increases and O decreases toward the surface of the film, almost as expected.

[0027] Example 2 Under the same conditions as in Example 1, the deposition of YF3 was limited to the surface 0.5 μm. That is, after depositing a 9.5 μm Y2O3 film, the Y2O3 rate was linearly decreased from 3.2 to 4.2 Å / sec, while the YF3 rate was linearly increased from 0 to 4.1 Å / sec, as in Example 1.

[0028] As a result, when the surface composition was measured using EDX, it was found to be Y:1, O = 1.22 at%, F = 0.78 at%. The F content is high because there is a lot of F on the surface. This shows that the oxygen and fluorine ratio can be freely controlled by controlling the deposition rate of Y2O3 and YF3.

[0029] Example 3 Next, we investigated the change in film formation rate over time using a simple etching apparatus for 300 mm diameter. Figure 7 shows a schematic diagram of the simple etching apparatus used in the experiment. The chamber walls were covered with alumina as much as possible. The substrate stage was made of anodized aluminum (A5052), with a 20 mm thick alumina layer installed on top. A Si substrate was placed on this alumina, and plasma was generated by applying 2 kW and 13.56 MHz to the RF coil. The distance between the Si substrate and the window was set to 100 mm.

[0030] The etching gas was CF4: 100 sccm, O2: 70 cm, and Ar: 10 sccm. The etching rates of the center and periphery of the Si substrate over the etching time were measured when the surface protection film was Y2O3 only and when the film of Example 1 was used.

[0031] 8, the etching rate ratio when the etching rate at an integrated etching time of 30 hours is set to 1, takes 25 hours for the etching rate to stabilize when a Y2O3 film is formed on the window, but stabilizes in 10 hours in Example 1. This is because the Y2O3 on the window gradually fluorides, causing the amount of F radicals to become unstable.

[0032] The surface protection film currently in use is Y2O3, and the problem is that it takes time for the surface to fluorinate. The etching gas used here is CF4: 100sccm, O2: 50sccm, Ar: 70cm, which contains more oxygen than normal CF4 and O2 etching. With CF4 and an O2 ratio of 20%, the Y2O3 surface is fluorinated to a state close to YF3.

[0033] The etching gas composition varies greatly depending on the etching process used, but in Example 3, a larger amount of oxygen was added so that an etching stop could be used. From the above, it is easy to imagine that the YOxFy composition needs to be optimized by controlling the etching gas composition.

[0034] On the other hand, it has been reported that even if a YOxFy film with a constant surface composition is formed, F diffuses in the depth direction of the film during the etching process (Non-Patent Document 2). Although the etching process ultimately results in a compositionally graded film, a more stable film can be obtained by starting with a compositionally graded film.

[0035] The reason for continuous processing in a vacuum is that once the Y2O3 film is exposed to the atmosphere and cooled to room temperature, it will absorb moisture from the air, so it is preferable to perform continuous film formation in a vacuum to avoid the effects of water. [Industrial Applicability]

[0036] To provide a structure with excellent particle resistance that is used in an environment exposed to corrosive plasma, such as a semiconductor manufacturing equipment component. [Explanation of symbols]

[0037] 1 IAD device 2 boards 3 Holder 4 Evaporation Source 5. Heater 6 Ion Gun 7. Electron Beam 8 Vacuum exhaust system 9 Film Thickness Monitor

Claims

1. Y is applied to the surface of an alumina or quartz substrate. ２ O ３ Membrane and YO ｘ F ｙ A film formation method for continuously forming films (x=0 to 1.5, y=0 to 3, and x and y are not simultaneously 0) in a vacuum, comprising: The Y ２ O ３ After the film is formed on the substrate surface under fixed conditions to a certain thickness, the evaporation source Y ２ O ３ and evaporation source YF ３ and evaporating the evaporation source Y ２ O ３ The film is formed by evaporation of Y ２ O ３ The deposition rate of the evaporation source YF ３ YF is deposited by evaporation of ３ By changing the film formation rate of the YO ｘ F ｙ The composition of the film is Y ２ O ３ From YF ３ The film can be formed by arbitrarily setting the time between An ion-assisted deposition method in which the F ratio in the composition of the YO x F y film is increased from the interface with the Y 2 O 3 film toward the surface of the YO x F y film, thereby forming a composition gradient.

2. The Y ２ O ３ The film thickness is 5 to 15 μm. The above YO ｘ F ｙ 2. The ion-assisted deposition method according to claim 1, wherein the thickness of the film is 1 to 5 μm.

3. 3. The ion-assisted deposition method according to claim 1, wherein the film is continuously formed while controlling the temperature of the substrate to 300°C.

4. A method for manufacturing a semiconductor manufacturing equipment member, which utilizes the ion-assisted deposition method according to any one of claims 1 to 3.

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