A quartz tuning fork resonator and a manufacturing method thereof

Abstract

The application provides a quartz tuning fork resonator and a manufacturing method thereof, which comprises a base, a pair of vibration arms formed on the base, and a counterweight region formed at an end of the vibration arms away from the base, wherein an upper surface of the counterweight region is formed with a metal film layer, a blank gap is left between an edge of the metal film layer and a physical edge of the counterweight region, and the thickness of the metal film layer gradually decreases from a central region to an edge region. The application improves the controllability of film layer distribution by setting the blank gap and the gradient metal film layer with a central thickness and an edge thickness, completely inhibits the metal vapor superposition of the edge and the sidewall of the counterweight region from the structural level, eliminates the local stress concentration, and improves the long-term frequency stability.

Description

Technical Field

[0001] This invention relates to the field of quartz resonator technology, and in particular to a quartz tuning fork resonator and its manufacturing method. Background Technology

[0002] Quartz tuning fork resonators are widely used in clock, communication, and sensing fields due to their advantages such as high frequency stability, low power consumption, and small size. In the manufacturing process of quartz tuning fork resonators, a counterweight area is typically placed at the end of the vibrating arm, and a metal film layer is deposited on the surface of the counterweight area. The natural frequency of the resonator is adjusted through the mass loading effect.

[0003] In existing technologies, the metal film layer in the counterweight area is typically deposited using vacuum evaporation or sputtering, and the deposition area is often defined by a mask. To ensure complete coverage of the counterweight area surface, the aperture size of existing masks is often basically the same as, or even slightly larger than, the size of the counterweight area. Under these process conditions, the metal evaporation flux tends to overlap at the edges and sidewalls of the counterweight area, resulting in abnormally thickened film layers at the edges or corners.

[0004] This uneven film thickness directly alters the effective mass distribution in the counterweight area, introducing localized stress concentration, increasing the frequency dispersion of resonators in the same batch, and adversely affecting the long-term frequency stability of the devices. Existing improvement solutions mostly focus on adjusting the evaporation angle, reducing the thickness of a single coating, or compensating through subsequent adjustment processes. However, these methods are still passive corrections to the coating results, making it difficult to actively control the film thickness distribution during the coating stage. Furthermore, the processes are highly complex and not conducive to industrial mass production.

[0005] Therefore, it is necessary to provide a new quartz tuning fork resonator structure and its fabrication method, which can suppress abnormal coating at the edge of the counterweight area while improving the effective mass utilization rate of the counterweight area, thereby achieving a balance between film uniformity and counterweight efficiency. Summary of the Invention

[0006] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a quartz tuning fork resonator to solve the problem of frequency dispersion caused by uneven film thickness in the counterweight region in the prior art; at the same time, this invention also provides a method for manufacturing the quartz tuning fork resonator.

[0007] To achieve the above and other related objectives, the present invention provides the following technical solutions: A first aspect of the present invention provides a quartz tuning fork resonator, comprising: Base; A pair of vibrating arms formed on the base; A counterweight area is formed at the end of the vibrating arm opposite to the base; The upper surface of the counterweight area is formed with a metal thin film layer, and a gap is left between the edge of the metal thin film layer and the physical edge of the counterweight area; and the thickness of the metal thin film layer gradually decreases from the center area to the edge area, forming a structure that is thick in the center and thin at the edge.

[0008] Furthermore, the metal thin film layer is a continuous and gapless dense film layer. The thickness difference between the central region and the edge region of the metal thin film layer is a slight gradient difference formed by the vacuum evaporation process, without any local thickening areas. That is, the metal thin film layer forms a continuous and smooth film thickness gradient distribution on the upper surface of the counterweight area, avoiding stress concentration caused by abrupt changes in thickness.

[0009] Furthermore, the thickness difference between the central region and the edge region of the metal thin film layer is 2-5 μm.

[0010] Furthermore, the thickness of the central region of the metal thin film layer is 5-10 μm, and the thickness of the edge layer is 3-5 μm.

[0011] Furthermore, the metal thin film layer is made of gold, silver, aluminum, or their alloys, which is compatible with the material characteristics of the quartz tuning fork, ensuring the bonding force between the film layer and the counterweight area, while utilizing the mass characteristics of gold and silver to achieve precise frequency fine-tuning.

[0012] Furthermore, the bonding force between the metal thin film layer and the counterweight area is ≥50MPa.

[0013] Furthermore, the thickness gradient direction of the metal thin film layer is set along the length direction and / or width direction of the vibrating arm.

[0014] Furthermore, the thickness gradient of the metal thin film layer is set along the length of the vibrating arm to match the main vibration mode of the quartz tuning fork, ensuring the coordination between mass distribution and vibration stiffness and improving frequency stability.

[0015] Furthermore, the width of the blanking gap is 5-20 μm, with a uniformity of ±2 μm.

[0016] A second aspect of the present invention provides a method for manufacturing the above-described quartz tuning fork resonator, comprising the following steps: (1) A quartz tuning fork substrate is provided, and a pair of vibrating arms and a counterweight area located at the end of the vibrating arms are formed on the quartz tuning fork substrate; (2) Prepare a mask with a gradient opening, the mask including a support part and a mask part disposed on the support part, the support part is provided with a through hole corresponding to the counterweight area, the mask part is provided with a plurality of through openings above the through holes, the aperture of the openings gradually decreases from the center area of ​​the counterweight area to the edge area, forming a mask with a gradient opening. (3) The mask prepared in step (2) is attached to the quartz tuning fork substrate so that the through holes of the mask are precisely aligned with the counterweight area; (4) The substrate with the mask attached is placed into the vacuum coating chamber for coating. After coating, it is cooled to room temperature and the mask is removed, so that a metal thin film layer with a thick center and thin edge is deposited in the counterweight area, and the quartz tuning fork resonator is obtained.

[0017] In step (1), a pair of vibrating arms and a counterweight area located at the end of the vibrating arms are formed on the quartz tuning fork substrate using photolithography and wet etching processes. The dimensional tolerance of the counterweight area is controlled to be ±3μm, and the surface roughness Ra≤0.05μm.

[0018] In step (2), the projection shape of the through hole on the plane is similar to that of the counterweight area, but its outline size is smaller than that of the actual size of the counterweight area, so that there is a blank gap between the edge of the metal film layer after coating and the physical edge of the counterweight area, which physically prevents the deposition of metal film on the sidewall and edge of the counterweight area, thereby avoiding abnormal thickening of the film layer in these areas due to geometric effects.

[0019] Furthermore, the projected size of the through hole on the plane is 5-20 μm smaller than the actual size of the counterweight area.

[0020] Furthermore, the maximum aperture of the opening in the central region is 20-30 μm, and the minimum aperture of the opening in the edge region is 5-10 μm, with an aperture gradient accuracy of ≤±5 μm.

[0021] Furthermore, the multiple openings are arranged in a matrix.

[0022] In step (2), the support and mask are made of metal or alloy.

[0023] Furthermore, the support portion has an anti-stick coating plated on the bottom surface facing the quartz tuning fork substrate.

[0024] Furthermore, the anti-stick coating is a polytetrafluoroethylene coating with a thickness of 1-3 μm, which can effectively prevent metal vapor deposition materials from adhering to the mask surface and improve the reusability of the mask; the adhesion between the anti-stick coating and the bottom surface of the support is ≥30 MPa.

[0025] In step (3), the center of the mask through hole coincides with the center of the counterweight area, and the alignment error is ≤ ±3μm.

[0026] In step (3), the mask is attached to the quartz tuning fork substrate using a visual alignment tool. The mask is then tightly attached to the substrate by vacuum adsorption, with an adsorption force of -0.08 to -0.09 MPa. After attachment, the support part of the mask is lightly pressed with a silicone elastic sheet with a hardness of 60HA.

[0027] In step (4), the coating includes basic film deposition and fine-tuning film replenishment, specifically: Basic film deposition: The vacuum level of the vacuum deposition chamber is controlled to 5×10 -4 -2×10 -3 Pa uses electron beam evaporation or thermal evaporation to deposit metal vapor deposition material onto the counterweight region of a quartz tuning fork substrate. The evaporation rate is controlled at 5-10 Å / s and the deposition time is 30-60s, forming a basic gradient metal thin film in the counterweight region.

[0028] Fine-tuning film replenishment: Keep the vacuum level of the vacuum deposition chamber constant, adjust the evaporation rate to 2-5 Å / s, continue to deposit the same metal evaporation material, and the deposition time is 10-25s to replenish the surface of the basic gradient metal thin film in a small amount to form a metal thin film layer with a continuously varying thickness.

[0029] Furthermore, the vertical distance between the vapor deposition source and the substrate is 70-80cm.

[0030] Furthermore, the substrate with the mask attached is placed into the vacuum coating chamber, first vacuum-baked at 80-100℃ for 15 minutes to remove gas, and then vacuum coating is performed.

[0031] In step (4), the metal vapor deposition material is gold, silver, aluminum or an alloy thereof.

[0032] As described above, the quartz tuning fork resonator and its manufacturing method of the present invention have the following beneficial effects: 1. The quartz tuning fork resonator of the present invention improves the controllability of the film distribution by setting a blank gap and a gradient metal thin film layer with a thick center and thin edges in the counterweight area, thoroughly suppressing the superposition of metal vapor at the edge and sidewall of the counterweight area from the structural level, eliminating local stress concentration, and improving long-term frequency stability.

[0033] 2. By setting the thickness gradient direction of the metal thin film layer along the length direction of the vibrating arm, the present invention can match the main vibration mode of the quartz tuning fork, which can significantly reduce the frequency dispersion of the quartz tuning fork resonator and improve the consistency and long-term frequency stability of the device.

[0034] 3. The mask of the present invention adopts a combination design of support part and mask part, which can form a continuous and gapless dense metal thin film layer without any local abrupt increase, thus avoiding stress concentration caused by abrupt change in thickness.

[0035] With the addition of a polytetrafluoroethylene (PTFE) anti-stick coating, the mask can be reused ≥50 times, reducing the cost of production consumables. Furthermore, the entire preparation process is compatible with existing vacuum coating, photolithography, and micromachining processes, requiring no complex equipment modifications and making industrial mass production highly feasible.

[0036] 4. The coating process parameters of the present invention can ensure the density and adhesion of the film layer, and the deposition efficiency is high, while taking into account the efficiency requirements of industrial mass production; the clearly defined parameters of film layer thickness, thickness difference and blank gap achieve a balance between film layer uniformity and counterweight efficiency. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the quartz tuning fork resonator disclosed in Embodiment 1 of the present invention.

[0038] Figure 2 This is a partial side view of the quartz tuning fork resonator disclosed in Embodiment 1 of the present invention.

[0039] Figure 3 This is a planar schematic diagram of the mask disclosed in Embodiment 2 of the present invention.

[0040] Figure 4 This is a cross-sectional schematic diagram of the mask disclosed in Embodiment 2 of the present invention.

[0041] Figure 5 This is a planar schematic diagram of the mask disclosed in Embodiment 3 of the present invention.

[0042] Component designation explanation 1. Base; 2. Vibrating arm; 3. Counterweight area; 4. Metal thin film layer; 5. Mask; 51. Support part; 52. Mask part; 53. Through hole; 54. Opening. Detailed Implementation

[0043] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. It should be noted that, unless otherwise specified, the following embodiments and features described herein can be combined with each other.

[0044] Example 1 Please see Figure 1-2 This embodiment provides a quartz tuning fork resonator, including a base 1; a pair of vibrating arms 2 formed on the base 1; and a counterweight region 3 formed at the end of the vibrating arms 2 opposite to the base 1. The base 1, serving as the supporting structure for the entire resonator, is made of high-purity quartz crystal material, exhibiting excellent mechanical and temperature stability. The vibrating arms 2 extend from the base 1, parallel to each other and symmetrically distributed on both sides of the base 1, forming a symmetrical fork-like structure. Each vibrating arm 2 has a slender rectangular cross-section, with its length along the extension direction of the base 1. The counterweight region 3 is located at the end of each vibrating arm 2 opposite to the base 1, i.e., the free end of the vibrating arm 2. The function of the counterweight region 3 is to adjust the mass distribution of the vibrating arms 2, thereby precisely controlling the resonant frequency.

[0045] like Figure 1As shown, a metal thin film layer 4 is formed on the upper surface of the counterweight area 3, with a gap between the edge of the metal thin film layer 4 and the physical edge of the counterweight area 3. The width of the gap is 5-20 μm, with a uniformity of ±2 μm. This design avoids the metal thin film layer 4 extending to the side of the counterweight area 3, preventing stress concentration and the risk of film peeling, while ensuring good adhesion between the film and the quartz substrate.

[0046] like Figure 2 As shown, the thickness of the metal thin film layer 4 gradually decreases from its central region to its edge region, forming a structure that is thicker at the center and thinner at the edge. Moreover, the metal thin film layer 4 is a continuous and dense film layer without gaps. The thickness difference between the central region and the edge region of the metal thin film layer 4 is a slight gradient difference formed by the vacuum evaporation process, without any local thickening areas. That is, the metal thin film layer 4 forms a continuous and smooth film thickness gradient distribution on the upper surface of the counterweight region 3, avoiding stress concentration caused by abrupt changes in thickness.

[0047] The thickness of the central region of the metal thin film layer 4 is 5-10 μm, and the thickness of the edge region is 3-5 μm, with a thickness difference of 2-5 μm between the central and edge regions. This thickness difference range ensures sufficient frequency tuning capability while avoiding thin film cracking or peeling caused by excessive stress gradient.

[0048] Furthermore, the metal thin film layer 4 is made of gold, silver, aluminum, or their alloys. Gold films possess excellent chemical stability and conductivity, making them suitable for high-precision frequency control applications; silver films offer the best conductivity but require a protective layer to prevent oxidation; aluminum films are less expensive and have a simpler manufacturing process, making them suitable for applications with general precision requirements. The bonding force between the metal thin film layer 4 and the counterweight region 3 reaches over 50 MPa, achieved through surface cleaning and plasma activation treatment before metal deposition, ensuring that the film will not peel off during long-term vibration.

[0049] In this embodiment, the thickness gradient of the metal thin film layer 4 is set along both the length and width directions of the vibrating arm 2. The thickness gradient along the length direction mainly affects the bending stiffness distribution of the vibrating arm 2, thereby adjusting the node position of the vibration mode; the thickness gradient along the width direction affects the torsional characteristics of the vibrating arm 2, which helps to suppress unwanted vibration modes. By simultaneously achieving thickness gradients in both directions, the frequency characteristics and temperature coefficient of the resonator can be controlled more precisely.

[0050] The working principle of this quartz tuning fork resonator is based on the piezoelectric effect of quartz crystal. When an alternating voltage is applied to the vibrating arm 2, the quartz crystal undergoes mechanical deformation, producing bending vibration. Since the vibration phases of the two vibrating arms 2 are opposite, the center of gravity of the entire resonator remains stable, and the vibrational energy is mainly concentrated on the vibrating arms 2, with very little transmitted to the base 1, thus achieving a high quality factor. The metal thin film layer 4 on the counterweight area 3 not only provides electrode functionality but also adjusts the resonant frequency through its mass effect. The gradually varying thickness design makes frequency adjustment more precise and stable, while reducing the impact of temperature changes on frequency stability.

[0051] Example 2 This embodiment provides a method for manufacturing the quartz tuning fork resonator in Embodiment 1. This method achieves thickness gradient control of the metal thin film layer in the counterweight area through a gradient aperture mask technique, thereby obtaining a high-precision frequency adjustment effect.

[0052] Specifically, the following steps are included: (1) A quartz tuning fork substrate is provided, and a pair of vibrating arms 2 and a counterweight area 3 located at the end of the vibrating arms 2 are formed on the quartz tuning fork substrate.

[0053] The quartz tuning fork substrate is made of high-quality quartz crystal material, and a standard tuning fork structure is formed through precision cutting and grinding processes. The vibrating arm 2 is designed as a slender cantilever beam structure, capable of generating bending vibrations under excitation. The counterweight area 3 is located at the free end of each vibrating arm 2, providing a load-bearing area for subsequent metal thin film deposition.

[0054] (2) Preparation of a mask with gradient openings 5: The mask 5 includes a support portion 51 and a mask portion 5 disposed on the support portion 51. The support portion 51 is the main frame structure of the mask 5, and has through holes 53 corresponding to the counterweight area 3. The projection shape of the through holes 53 on the plane is similar to that of the counterweight area 3, but its outline size is smaller than the actual size of the counterweight area 3. This design ensures accurate positioning of the mask 5 when it is bonded to the substrate, while avoiding interference of the edge of the mask 5 to the coating area.

[0055] The mask 5 is located above the through-hole 53, and multiple through-holes 54 are formed in this area. The diameter of these holes 54 gradually decreases from the center region of the counterweight area 3 to the edge region, forming a gradient hole diameter distribution. The maximum hole diameter of the hole 54 located in the central region is 20-30 μm, and the minimum hole diameter of the hole 54 located in the edge region is 5-10 μm. This gradient hole diameter design can form a corresponding thickness gradient during the coating process. Furthermore, the gradient direction of the hole diameter 54 is simultaneously set along the length and width directions of the vibrating arm 2.

[0056] The support portion 51 has an anti-stick coating deposited on the bottom surface of the quartz tuning fork substrate. The anti-stick coating is a polytetrafluoroethylene coating with a thickness of 1-3 μm. The adhesion between the anti-stick coating and the bottom surface of the support portion 51 is ≥30 MPa. This anti-stick coating effectively prevents the metal material from adhering to the surface of the mask 5 during the coating process, ensuring that the mask 5 can be removed smoothly without damaging the thin film layer on the substrate surface.

[0057] (3) The mask 5 prepared in step (2) is attached to the quartz tuning fork substrate so that the through hole 53 of the mask 5 is precisely aligned with the counterweight area 3.

[0058] During the bonding process, a visual alignment fixture is used to ensure the relative positional accuracy between the mask 5 and the substrate. The boundary of the through-hole 53 should completely surround the counterweight area 3 and maintain a uniform edge distance. Vacuum adsorption is used to tightly bond the mask 5 to the substrate; the adsorption force is -0.08 to -0.09 MPa. After bonding, a silicone elastic sheet with a hardness of 60 HA is used to gently press the support portion 51 of the mask 5, ensuring close contact between the mask 5 and the substrate surface to form a sealed coating area.

[0059] (4) Place the substrate with the mask 5 attached into the vacuum coating chamber for coating: The vacuum level is controlled at 5×10 throughout the coating process. -4 -2×10 -3 The deposition process employs electron beam evaporation or thermal evaporation, with a vertical distance of 70-80 cm between the evaporation source and the substrate. The deposition process comprises two stages: basic film deposition and fine-tuning film replenishment. In the basic film deposition stage, the evaporation rate is controlled at 5-10 Å / s, and the deposition time is 30-60 s. This stage primarily establishes the basic thickness distribution of the film. In the fine-tuning film replenishment stage, the evaporation rate is adjusted to 2-5 Å / s, and the same metal evaporation material is deposited for 10-25 s. This stage is used to finely adjust the film thickness distribution and further optimize frequency characteristics.

[0060] Because the apertures 54 in mask 5 have a gradually varying diameter, when metal vapor reaches the surface of the counterweight region 3 through the apertures 54 of different diameters, a deposition distribution with a thicker center and thinner edges will be formed. The larger apertures 54 in the central region allow more metal vapor to pass through, forming a thicker thin film layer, while the smaller apertures 54 in the edge region restrict the amount of metal vapor passing through, forming a thinner thin film layer. After the coating is completed, the substrate is cooled to room temperature in a vacuum environment, and then mask 5 is removed, thus depositing a metal thin film layer 4 with a thick center and thin edges in the counterweight region 3, resulting in a quartz tuning fork resonator.

[0061] Using the above manufacturing method, a metal thin film layer 4 with a thickness gradient is formed in the counterweight region 3 of the quartz tuning fork resonator. The mass distribution of this thin film layer can precisely adjust the resonant frequency of the tuning fork. The thicker film in the central region provides the main frequency adjustment function, while the thinner film in the edge region enables fine frequency adjustment, thus improving the overall frequency stability and accuracy of the quartz tuning fork resonator. The design of the gradient aperture mask 5 avoids the frequency deviation problem that may occur with traditional uniform coating, and the application of the anti-stick coating ensures the reusability of the mask 5 and the consistency of coating quality.

[0062] Example 3 Please see Figure 5 This embodiment provides a quartz tuning fork resonator and its manufacturing method. Compared with embodiments 1 and 2, the only difference is that the aperture of the opening 54 on the mask 5 is set along the length direction of the vibrating arm 2, so that the thickness gradient direction of the metal thin film layer 4 is set only along the length direction of the vibrating arm 2.

[0063] In summary, this invention improves the controllability of film distribution by setting blank gaps and a gradient metal thin film layer that is thicker at the center and thinner at the edges in the counterweight area. This structurally suppresses the superposition of metal vapor at the edges and sidewalls of the counterweight area, eliminates local stress concentration, reduces product frequency dispersion, and improves long-term frequency stability. Therefore, this invention effectively overcomes the various shortcomings of existing technologies and has high industrial application value.

[0064] The terms used in this specification, such as "upper," "lower," "left," "right," "front," "back," "middle," and "one," are merely for clarity of description and are not intended to limit the scope of the invention. Any changes or adjustments to their relative relationships, without substantially altering the technical content, shall also be considered within the scope of the invention.

[0065] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. All equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this invention should still be covered by the claims of this invention.

Claims

1. A quartz tuning fork resonator, characterized in that, include: Base; A pair of vibrating arms formed on the base; A counterweight area is formed at the end of the vibrating arm opposite to the base; The upper surface of the counterweight area is formed with a metal thin film layer, and a gap is left between the edge of the metal thin film layer and the physical edge of the counterweight area; and the thickness of the metal thin film layer gradually decreases from its central region to its edge region.

2. The quartz tuning fork resonator according to claim 1, characterized in that, The thickness difference between the central and edge regions of the metal thin film layer is 2-5 μm.

3. The quartz tuning fork resonator according to claim 1, characterized in that, The metal film layer is made of gold, silver, aluminum or their alloys, and the bonding force between the metal film layer and the counterweight area is ≥50MPa.

4. The quartz tuning fork resonator according to claim 1, characterized in that, The thickness gradient direction of the metal thin film layer is set along the length direction and / or width direction of the vibrating arm.

5. A method for manufacturing a quartz tuning fork resonator, characterized in that, Includes the following steps: (1) A quartz tuning fork substrate is provided, and a pair of vibrating arms and a counterweight area located at the end of the vibrating arms are formed on the quartz tuning fork substrate; (2) Prepare a mask with a gradient opening, the mask including a support part and a mask part, the support part is provided with a through hole corresponding to the counterweight area, and the mask part is provided with a plurality of through openings above the through holes, the aperture of the openings gradually decreases from the center area of ​​the counterweight area to the edge area, forming a mask with a gradient opening. (3) The mask prepared in step (2) is attached to the quartz tuning fork substrate so that the through hole of the mask is precisely aligned with the counterweight area; (4) The substrate with the mask attached is placed into the vacuum coating chamber for coating. After coating, it is cooled to room temperature and the mask is removed, so that a metal thin film layer with a thick center and thin edge is deposited in the counterweight area, and the quartz tuning fork resonator is obtained.

6. The manufacturing method according to claim 5, characterized in that, In step (2), the projection shape of the through hole on the plane is similar to that of the counterweight area, but its outline size is smaller than that of the actual size of the counterweight area.

7. The manufacturing method according to claim 5, characterized in that, In step (2), the maximum aperture of the opening in the central region is 20-30 μm, and the minimum aperture of the opening in the edge region is 5-10 μm.

8. The manufacturing method according to claim 5, characterized in that, In step (2), the bottom surface of the support portion facing the quartz tuning fork substrate is coated with an anti-stick coating. The anti-stick coating is a polytetrafluoroethylene coating with a thickness of 1-3 μm. The adhesion between the anti-stick coating and the bottom surface of the support portion is ≥30 MPa.

9. The manufacturing method according to claim 5, characterized in that, In step (4), the vacuum level is controlled at 5×10 throughout the coating process. -4 -2×10 -3 Pa is deposited using electron beam evaporation or thermal evaporation, with the vertical distance between the evaporation source and the substrate being 70-80 cm.

10. The manufacturing method according to claim 5, characterized in that, In step (4), the coating includes base film deposition and fine-tuning film replenishment. The evaporation rate of the base film deposition is controlled at 5-10 Å / s and the deposition time is 30-60s. The evaporation rate of the fine-tuning film replenishment is adjusted to 2-5 Å / s, and the same metal evaporation material is deposited for another 10-25s.

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