A tin film, a preparation method thereof and a micro-nano device

Abstract

This invention provides a tin film, its preparation method, and micro / nano devices. The preparation method of the tin film includes the following steps: (1) fixing a cleaned substrate on the turntable support of an electron beam evaporation equipment; installing an evaporation boat containing tin film material on a turntable between the positive and negative electrodes of the electron gun, and covering the evaporation boat with a shield; (2) evacuating the vacuum chamber, then introducing an inert gas, and then heating the evaporation boat to a preset temperature, the preset temperature being 100-150°C; (3) opening the shield for evaporation when the electron gun beam current reaches the target beam current, the target beam current being 0.02-0.15A; (4) ending the evaporation when the thickness of the tin film reaches the target film thickness. The preparation method of this invention, by bombarding the molten tin film material with an electron beam, can prepare a tin film with good uniformity and no appearance defects, significantly improving the quality of the tin film.

Description

Technical Field

[0001] This invention belongs to the field of micro-nano device technology, specifically relating to a tin film, its preparation method, and micro-nano devices. Background Technology

[0002] Micro- and nano-devices are devices measured in micrometers or even nanometers, and mainly include micro- and nano-electronic devices, micro- and nano-optical devices, and micro- and nano-optoelectronic devices. One of the ways to connect the substrate and electronic components in micro- and nano-devices is by soldering, and tin, with its low melting point, can be used as a solder in the fabrication of micro- and nano-devices.

[0003] There are three main methods for depositing tin films on substrate surfaces in related technologies: hot-dip plating, electroplating, and magnetron sputtering. The semiconductor industry demands high-quality, low-thickness tin films, but each of these three common tin plating methods has its own drawbacks. Hot-dip plating uses a large amount of tin, easily produces tin dross and tin nodules, and is highly prone to uneven thickness and severe eccentricity. Electroplating is prone to problems such as thick coatings, burrs, and filamentous tendrils. Magnetron sputtering equipment has a complex structure and high cost, and because tin has a low melting point, magnetron sputtering requires lower power settings, resulting in a slow tin film deposition rate. Summary of the Invention

[0004] This invention aims to at least partially address one of the technical problems in related technologies. To this end, embodiments of this invention provide a tin film, a method for its preparation, and micro / nano devices.

[0005] The method for preparing the tin film according to an embodiment of the present invention includes the following steps:

[0006] (1) Fix the cleaned substrate on the turntable support of the electron beam evaporation equipment; install the evaporation boat containing tin film material on the turntable between the positive and negative electrodes of the electron gun, and cover the evaporation boat with a shield;

[0007] (2) Evacuate the vacuum chamber, then introduce inert gas, and then heat the evaporation boat to a preset temperature, which is 100-150°C;

[0008] (3) When the beam current of the electron gun reaches the target beam current, the shield is opened for vapor deposition. The target beam current is 0.02 to 0.15 A.

[0009] (4) The evaporation process ends when the tin film thickness reaches the target thickness.

[0010] The advantages and technical effects of the tin film preparation method of this invention are as follows:

[0011] (1) The embodiment of the present invention uses electron beam evaporation to prepare tin film. Compared with the tin plating method in related technologies, it can effectively solve the defects in the appearance of tin film and prepare a more uniform film, thus improving the quality of tin film.

[0012] (2) The preparation process of the present invention is simple, the amount of tin used for coating is small, the electron beam evaporation equipment has a simple structure, low cost and high production efficiency, and can effectively ensure the preparation of tin film at a low cost.

[0013] (3) The entire production process of this invention has no harmful substances emitted, making it green and environmentally friendly.

[0014] In some embodiments, in step (1), the rotational speed of the substrate is 5 to 20 rpm.

[0015] In some embodiments, in step (2), the preset temperature is 120 to 150°C.

[0016] In some embodiments, in step (2), the vacuum chamber is evacuated to 10... -3 ~10 -5 Pa, then inert gas is introduced to 0.2-0.8 Pa.

[0017] In some embodiments, in step (3), the target beam current is 0.06 to 0.12 A.

[0018] In some embodiments, in step (3), the shield is opened for vapor deposition after the electron gun beam reaches the target beam and stabilizes.

[0019] In some embodiments, in step (3), the electron gun beam rises in multiple stages until the electron gun beam reaches the target beam, after which the shield is opened for vapor deposition.

[0020] In some embodiments, in step (4), the target film thickness is 190–210 nm.

[0021] This invention also provides a tin film, which is prepared by the tin film preparation method of this invention.

[0022] The advantages and technical effects of the tin film in this embodiment of the invention are as follows:

[0023] Compared to tin films obtained using preparation methods in related technologies, the tin films of the present invention exhibit better uniformity and no obvious appearance defects.

[0024] This invention also provides a micro / nano device, including the tin film of this invention.

[0025] The advantages and technical effects of the micro / nano devices in this invention are as follows:

[0026] Because the tin film has better uniformity and no obvious appearance defects, the welding effect is greatly improved, resulting in good contact between the electronic components and the substrate in the micro-nano devices of the present invention. Attached Figure Description

[0027] Figure 1 This is a schematic flowchart of the method for preparing the tin film of the present invention. Detailed Implementation

[0028] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0029] This invention provides a method for preparing a tin film, comprising the following steps:

[0030] (1) Fix the cleaned substrate on the turntable support of the electron beam evaporation equipment; install the evaporation boat containing tin film material on the turntable between the positive and negative electrodes of the electron gun, and cover the evaporation boat with a shield;

[0031] (2) Evacuate the vacuum chamber, then introduce inert gas, and then heat the evaporation boat to a preset temperature, which is 100-150°C;

[0032] (3) When the beam current of the electron gun reaches the target beam current, the shield is opened for vapor deposition. The target beam current is 0.02 to 0.15 A.

[0033] (4) The evaporation process ends when the tin film thickness reaches the target thickness.

[0034] This invention employs electron beam evaporation to prepare tin films. Compared to several preparation methods disclosed in related technologies, evaporation deposition offers better film uniformity. Furthermore, because tin has a very low melting point, the beam current must be strictly controlled between 0.02A and 0.15A, such as 0.02A, 0.04A, 0.06A, 0.08A, 0.10A, 0.12A, 0.14A, and 0.15A. Adjusting the beam current further reduces film splashing, thereby improving the uniformity of the tin film. In addition, since tin itself has a low melting point, direct bombardment of the tin film material by the electron beam can easily cause the film material to splatter. Therefore, the process of gradually increasing the beam current of the electron gun to reach the target beam current can play a role in pre-melting the tin film material. At the same time, preheating the evaporation boat, such as to 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, etc., can assist in the pre-melting. The two work together to turn the tin film material into a high-temperature molten state. Then bombarding the tin film material in the high-temperature molten state can effectively reduce the tin film material splatter, thereby reducing the surface roughness of the tin film and improving the coating quality.

[0035] It should be noted that the preparation method of this invention does not particularly limit the type of substrate, and the type of substrate can be adjusted according to requirements. Furthermore, the preparation method of this invention does not particularly limit the cleaning method of the substrate, as long as it is clean enough to be suitable for subsequent coating.

[0036] In some embodiments, in step (1), the rotation speed of the substrate is 5 to 20 rpm, for example, 5 rpm, 8 rpm, 10 rpm, 12 rpm, 15 rpm, 18 rpm, 20 rpm, etc. A rotation speed of the substrate within the above range helps to improve the uniformity of the coating.

[0037] In some embodiments, the preset temperature in step (2) is 120–150°C, such as 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, 150°C, etc. When the preset temperature is too low, the effect of assisting pre-melting is weak, which is not conducive to turning the tin film material into a high-temperature molten state, and thus not conducive to reducing tin film material splashing, and thus not conducive to improving the uniformity of the coating. When the preset temperature is too high, the effect of assisting pre-melting will not be further improved, and it is not conducive to reducing costs and increasing efficiency.

[0038] In some embodiments, in step (2), the vacuum chamber is evacuated to 10... -3 ~10 -5 Pa, for example 1×10 - 3 Pa, 3×10 -3 Pa, 6×10 -3 Pa, 8×10 -3Pa, 1×10 -4 Pa, 3×10 -4 Pa, 6×10 -4 Pa, 8×10 -4 Pa, 1×10 - 5 Pa, 3×10 -5 Pa, 6×10 -5 The vacuum level is adjusted to 0.2–0.8 Pa, such as 0.2 Pa, 0.3 Pa, 0.4 Pa, 0.5 Pa, 0.6 Pa, 0.7 Pa, or 0.8 Pa. By controlling the vacuum level before and after the inert gas is introduced, the system can be kept in a high vacuum state, which can reduce the influence of impurities in the air on the coating.

[0039] In some embodiments, in step (3), the target beam current is 0.06–0.12 A, for example, 0.06 A, 0.07 A, 0.08 A, 0.09 A, 0.10 A, 0.11 A, 0.12 A, etc. When the target beam current is too small, the evaporation efficiency is low, which is not conducive to improving production efficiency. When the target beam current is too large, it is not conducive to reducing the degree of film splashing, thereby improving the uniformity of the tin film.

[0040] In step (3), the shield is opened for evaporation after the electron gun beam reaches the target beam and stabilizes. An important indicator for reducing tin film spatter is beam stability. If the beam fluctuates too much in a short period of time, it will cause excessive electron bombardment of the tin film, resulting in tin film spatter, which is not conducive to improving the coating quality. Therefore, it is preferable to open the shield for evaporation after the beam reaches the target beam and stabilizes for a period of time.

[0041] In some embodiments, in step (3), the electron gun beam current is increased in multiple stages until the electron gun beam current reaches the target beam current, at which point the shield is opened for vapor deposition. The beam current of the electron gun is affected by a variety of factors, such as the deposition rate, the power of the electron gun, and the vacuum level. Therefore, it is difficult to adjust the beam current of the electron gun to the target beam current in one go. Thus, it is preferable to increase the electron gun beam current in multiple stages. For example, the electron gun beam current is first increased to 0-0.1A, then stabilized at 0.1A for a period of time, then increased to 0.1-0.15A, then stabilized at 0.15A for a period of time, and finally the shield is opened for vapor deposition under a stable beam current of 0.15A. Another example is that the electron gun beam current is first increased to 0-0.07A, then stabilized at 0.07A for a period of time, then increased to 0.07-0.12A, then stabilized at 0.12A for a period of time, and finally the shield is opened for vapor deposition under a stable beam current of 0.12A.

[0042] In some embodiments, in step (4), the target film thickness is 190–210 nm. A tin film thickness within this range ensures good uniformity.

[0043] This invention also provides a tin film, which is prepared by the tin film preparation method of this invention.

[0044] Compared to tin films obtained using preparation methods in related technologies, the tin films of the present invention exhibit better uniformity and no obvious appearance defects.

[0045] This invention also provides a micro / nano device, including the tin film of this invention.

[0046] Because the tin film has better uniformity and no obvious appearance defects, the welding effect is greatly improved, resulting in good contact between the electronic components and the substrate in the micro-nano devices of the present invention.

[0047] The present invention will now be described in detail with reference to the embodiments and accompanying drawings.

[0048] Example 1

[0049] An electron beam evaporation method for tin deposition includes the following steps:

[0050] S1. Sample preparation: Prepare one sample. <100> A 6-inch monocrystalline silicon wafer with single-sided crystal polishing was used as the coating substrate. It was then subjected to ultrasonic cleaning with deionized water, anhydrous ethanol, and acetone in sequence to obtain a clean surface.

[0051] S2. Sample installation: The turntable of the electron beam evaporation equipment has a total of 16 substrate placement positions on the corner bar support. Use conductive tape or other methods to fix the substrate in the corresponding position to prevent it from falling off.

[0052] S3. Film material loading: Fill the tin film material into the evaporation boat and ensure that it is level. Place the evaporation boat containing the tin film material on the turntable between the positive and negative electrodes of the electron gun and cover the evaporation boat with a shield.

[0053] S4. Equipment parameter settings and operation: Evacuate the vacuum chamber to 5×10⁻⁶. -4 Pa, then argon gas is introduced to 4 × 10⁻⁶. -1 Pa, heat the evaporation boat containing the coating material to 100°C; after the temperature stabilizes, turn on the power of the electron gun, as shown in Table 1, gradually increase the power of the electron gun to control the beam current to 0.15A, and open the shield to start the evaporation process.

[0054] S5. Film thickness monitoring: During the coating process, a crystal oscillator is used to detect the film thickness. The crystal oscillator is placed at the same height as the substrate. The coating process can be stopped when the film thickness reaches the set value of 200nm.

[0055] S6. End of coating: After coating is completed, turn off the electron gun power, stop the argon gas supply, and vent the chamber to complete the entire coating process.

[0056] Example 2

[0057] The preparation method in this embodiment is the same as that in embodiment 1, except that in step S4, the power of the electron gun is gradually increased to control the beam current to 0.13A.

[0058] Example 3

[0059] The preparation method in this embodiment is the same as that in embodiment 1, except that in step S4, the power of the electron gun is gradually increased to control the beam current to 0.12A.

[0060] Example 4

[0061] The preparation method in this embodiment is the same as that in embodiment 1, except that in step S4, the power of the electron gun is gradually increased to control the beam current to 0.07A.

[0062] Table 1. Parameters of beam current control before evaporation and beam current and coating rate during evaporation in the preparation methods of Examples 1-4

[0063]

[0064] The thickness of the tin film prepared by the preparation methods of Examples 1-4 was tested at at least 10 different locations on the same tin film. The results showed that the thickness was within the range of 200±10nm. The actual thickness value had a small error compared with the target thickness of 200nm, indicating that the tin film prepared by the preparation methods of Examples 1-4 had good uniformity.

[0065] In addition, by observing the appearance of the tin films prepared by the methods in Examples 1-4, no appearance defects such as tin dross, tin nodules, burrs, or filamentous tendrils were found.

[0066] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0067] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for producing a tin film, characterized by, The method comprises the following steps: (1) fixing a cleaned substrate on a rotary table foot rod support of an electron beam evaporation device; installing a tin film material containing evaporation boat between the positive and negative electrodes of an electron gun and covering the evaporation boat with a shield; (2) vacuumizing a vacuum chamber, then introducing inert gas, and then heating the evaporation boat to a preset temperature, which is 100-150 DEG C; (3) the beam current of the electron gun is raised in multiple stages until the beam current reaches a target beam current and is stable, then the shield is opened to perform evaporation, and the target beam current is 0.02-0.15 A; (4) the evaporation is ended when the thickness of the tin film reaches a target film thickness.

2. The method for producing a tin film according to claim 1, wherein In step (1), the rotation rate of the substrate is 5-20 rpm.

3. The method of claim 1, wherein the tin film is formed by sputtering. In step (2), the preset temperature is 120-150 DEG C.

4. The method for producing a tin film according to claim 1 or 3, characterized in that, In step (2), the vacuum chamber is evacuated to 10 -3 ~10 -5 Pa, and then an inert gas is introduced to 0.2 to 0.8 Pa.

5. The method of claim 1, wherein the tin film is formed by sputtering. In step (3), the target beam current is 0.06-0.12 A.

6. The method of claim 1, wherein the tin film is formed by sputtering. In step (4), the target film thickness is 190-210 nm.

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