阅读说明：本技术 在微通道板通道阵列制备复合金属膜层过程中减少开口面积比损失量的工艺及微通道板 (Process for reducing specific loss of opening area in process of preparing composite metal film layer by using microchannel plate channel array and microchannel plate ) 是由 高鹏 邱祥彪 张正君 李臻 丛晓庆 王健 李婧雯 孙赛林 王鹏飞 于 2021-06-29 设计创作，主要内容包括：本发明提供一种在微通道板通道阵列制备复合金属膜层过程中减少开口面积比损失量的工艺以及微通道板,包括以下步骤：提供密集排列的圆形微孔阵列的基底；在真空环境下,在所述圆形微孔阵列的圆形微孔输入面和一定深度的内壁采用两种材料先后蒸镀的方式进行叠加,形成顺序层叠结构ABA,其中A层为镍铬合金层,B层为金属银或者铜层。本发明通过在微通道板输入面及一定深度内壁蒸镀复合金属膜层,既满足面电阻技术指标要求,同时避免传统厚度太厚、开口面积比损失较大的问题。(The invention provides a process for reducing the loss amount of an opening area ratio in the process of preparing a composite metal film layer by a microchannel plate channel array and a microchannel plate, comprising the following steps of: providing a substrate with a densely arranged circular micropore array; in a vacuum environment, two materials are sequentially overlaid on the circular micropore input surface of the circular micropore array and the inner wall with a certain depth in an evaporation mode to form a sequential laminated structure ABA, wherein the layer A is a nickel-chromium alloy layer, and the layer B is a metal silver or copper layer. According to the invention, the composite metal film layer is evaporated on the input surface and the inner wall of a certain depth of the microchannel plate, so that the technical index requirement of the surface resistance is met, and the problems of too thick thickness and large loss of the opening area ratio in the traditional method are avoided.)

1. A process for reducing the loss amount of an opening area ratio in the process of preparing a composite metal film layer by a micro-channel plate channel array is characterized by comprising the following steps:

providing a substrate with a densely arranged circular micropore array;

in a vacuum environment, two materials are sequentially overlaid on the circular micropore input surface of the circular micropore array and the inner wall with a certain depth in an evaporation mode to form a sequential laminated structure ABA, wherein the layer A is a nickel-chromium alloy layer, and the layer B is a metal silver or copper layer.

2. The process of claim 1, wherein the thickness of the layer a is 2 times the thickness of the layer B.

3. The process of claim 1, wherein the thickness of the layer a is 20nm and the thickness of the layer B is 10 nm.

4. The process according to claim 1, wherein the diameter of the circular micropores in the circular micropore array is phi 6um, the hole pitch between adjacent circular micropores is 7.5um, and the length of the circular micropores is 0.33 mm.

5. The process for reducing the loss amount of the opening area ratio in the process of preparing the composite metal film layer by the micro-channel plate channel array according to any one of claims 1 to 4, wherein the specific preparation steps of the process comprise:

providing a substrate of a densely arranged circular micropore array, cleaning, drying, and placing on a tool rack in a vacuum coating machine;

vacuumizing to make the vacuum degree in the vacuum coating machine reach 1 x 10^-1Pa, carrying out vacuum baking on the substrate at the temperature of 200 ℃;

starting the evaporation of the nickel-chromium alloy film layer after baking;

after the evaporation of the nickel-chromium alloy film layer is finished, rotating the coating material crucible, and starting the evaporation of the metal silver or copper film layer;

after the evaporation of the metallic silver or copper film layer is finished, rotating the coating material crucible again, and starting the evaporation of the nickel-chromium alloy film layer;

and in the evaporation process, the thickness of each film layer of the ABA sequential laminated structure is controlled within a preset range.

6. A microchannel plate made according to the method of any one of claims 1-5.

Technical Field

The invention relates to the technical field of microchannel plates, in particular to a process for reducing the specific loss of an opening area in the process of preparing a composite metal film layer by a microchannel plate channel array and a microchannel plate.

Background

The microchannel plate is a large-area array channel electron multiplier, and is formed by regularly arranging millions of circular channels, and electrons are multiplied by the inner wall materials of circular holes in elements. The microchannel plate needs to be electrified in the working process, so that the two surfaces of the element are coated with films to play a role in conducting electricity. The opening area ratio is the ratio of the channel opening area of the working area of the microchannel plate to the area of the whole working area, and the opening area ratio determines the detection efficiency of the microchannel plate and influences the gain and noise factor of the microchannel plate to a certain extent, which is one of the key performances of the microchannel plate.

In order to increase the opening area ratio of the microchannel plate, various measures are adopted in the prior art, such as reducing the thickness of the leather or the shape of the entrance of the channel, for example, the measures proposed in chinese patent with publication number CN207282449 are low delay pulse, low crosstalk, and high collection efficiency microchannel plate, wherein each channel comprises an input port arranged on the input electrode layer and an output port arranged on the output electrode layer; the input port is communicated with the upper end of the channel, and the output port is communicated with the lower end of the channel; the input ports are tapered from top to bottom to form a microchannel plate having a channel opening area greater than 90%. The existing measures have higher difficulty in manufacturing process and lower qualification rate, cannot realize industrial batch production, and are only suitable for application in special fields.

Reducing the loss of the opening area ratio after the evaporation of the metal film layer is a feasible method for improving the opening area ratio without changing the basic process. On the premise of ensuring that the surface resistance meets the technical index, the thickness of the metal film layer is reduced, and the purpose of improving the opening area ratio is achieved compared with the original normal process. The thinning of the nickel-chromium film layer inevitably leads to the increase of the value of the surface resistance, and in order to ensure the surface resistance, the film layer is thinned, and metal with smaller resistivity is introduced to be used as a conductive film layer. After the film material is determined, the film coating process needs to be improved, and the film coating effect needs to be optimized.

With the development of the scientific research of the nano film material, various advanced coating technologies are developed. The film coating becomes the mainstream by the gas phase transfer mode, and the method is mainly divided into two categories including: physical vapor deposition and chemical vapor deposition. Physical vapor deposition, which refers to a process of transferring atoms or molecules from a source to the surface of a substrate by utilizing a physical process, and comprises vacuum thermal evaporation, electron beam evaporation, magnetron sputtering and the like; chemical vapor deposition, in which a reaction substance is chemically reacted under a gaseous condition to generate a solid substance, and the solid substance is deposited on the surface of a solid substrate. The two coating methods have respective advantages and disadvantages. The advantages of chemical vapor deposition are that the coating is carried out on the irregular surface and the compactness of the film layer is good, and the coated film layer is mainly made of compounds and has thinner thickness. The physical vapor deposition is more suitable for plating a film layer on a plane, and the film layer with thicker thickness is plated. Therefore, a physical vapor deposition coating mode is selected, the evaporation temperature selectivity of vacuum thermal evaporation to a coating material is smaller, the vacuum thermal evaporation is not suitable for high-melting-point metal materials, the energy of an electron beam melting material is concentrated and larger, and the vacuum thermal evaporation coating method is suitable for coating a metal film layer with a higher melting point.

For example, in the method and the evaporation method for improving the resolution of the microchannel plate proposed in chinese patent application with publication No. CN110400738A, a metal material film is evaporated on the output end surface of the microchannel plate to cover the original output nickel-chromium electrode of the microchannel plate, the metal material film is evaporated by using platinum (Pt)/nickel (Ni)/gold (Au)/silver (Ag) metal material, the work function of the metal material film is higher than 4.0eV, and the resolution of the microchannel plate is improved by using the high work function of the newly-plated metal film material. The final double-layer composite film layer formed on the output end face is formed by two metal materials, wherein the metal material also comprises silver, but the double-layer composite film layer cannot be directly or indirectly applied to solve the problem of the specific loss of the opening area of the input face of the microchannel plate.

Prior art documents:

patent document 1CN207282449U

Patent document 2CN110400738A

Disclosure of Invention

The invention aims to provide a process for reducing the loss of the opening area ratio in the process of preparing a composite metal film layer by a microchannel plate channel array and a microchannel plate.

In order to achieve the above object, a first aspect of the present invention provides a process for reducing loss of an open area ratio in a process of preparing a composite metal film layer by using a microchannel plate channel array, comprising:

providing a substrate with a densely arranged circular micropore array;

in a vacuum environment, two materials are sequentially overlaid on the circular micropore input surface of the circular micropore array and the inner wall with a certain depth in an evaporation mode to form a sequential laminated structure ABA, wherein the layer A is a nickel-chromium alloy layer, and the layer B is a metal silver or copper layer.

Preferably, the thickness of the a layer is 2 times the thickness of the B layer.

Preferably, the thickness of the A layer is 20nm and the thickness of the B layer is 10 nm.

Preferably, the diameter of the circular micropores in the circular micropore array is phi 6um, the hole distance between adjacent circular micropores is 7.5um, and the length of the circular micropores is 0.33 mm.

Preferably, the specific preparation steps of the process for reducing the specific loss of the opening area in the process of preparing the composite metal film layer by the microchannel plate channel array comprise:

providing a substrate of a densely arranged circular micropore array, cleaning, drying, and placing on a tool rack in a vacuum coating machine;

vacuumizing to make the vacuum degree in the vacuum coating machine reach 1 x 10^-1Pa, carrying out vacuum baking on the substrate at the temperature of 200 ℃;

starting the evaporation of the nickel-chromium alloy film layer after baking;

after the evaporation of the nickel-chromium alloy film layer is finished, rotating the coating material crucible, and starting the evaporation of the metal silver or copper film layer;

after the evaporation of the metallic silver or copper film layer is finished, rotating the coating material crucible again, and starting the evaporation of the nickel-chromium alloy film layer;

and in the evaporation process, the thickness of each film layer of the ABA sequential laminated structure is controlled within a preset range.

According to a second aspect of the present invention, there is provided a microchannel plate prepared according to the foregoing process.

It should be understood that all combinations of the foregoing concepts and additional concepts described in greater detail below can be considered as part of the inventive subject matter of this disclosure unless such concepts are mutually inconsistent. In addition, all combinations of claimed subject matter are considered a part of the presently disclosed subject matter.

The foregoing and other aspects, embodiments and features of the present teachings can be more fully understood from the following description taken in conjunction with the accompanying drawings. Additional aspects of the present invention, such as features and/or advantages of exemplary embodiments, will be apparent from the description which follows, or may be learned by practice of specific embodiments in accordance with the teachings of the present invention.

Drawings

The drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component that is illustrated in various figures may be represented by a like numeral. For purposes of clarity, not every component may be labeled in every drawing. Embodiments of various aspects of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 is a schematic view of a composite film layer structure of the present invention

FIG. 2 is a schematic view showing calculation of the ratio of the area of the openings after coating

FIG. 3 is a schematic diagram of the opening area ratio of different film thicknesses at different coating depths.

Fig. 4 is a comparison of an input conductive layer and a composite conductive layer of a conventional film layer.

Fig. 5 is a schematic structural view of a coating rate selecting device.

Detailed Description

In order to better understand the technical content of the present invention, specific embodiments are described below with reference to the accompanying drawings.

In this disclosure, aspects of the present invention are described with reference to the accompanying drawings, in which a number of illustrative embodiments are shown. Embodiments of the present disclosure are not necessarily intended to include all aspects of the invention. It should be appreciated that the various concepts and embodiments described above, as well as those described in greater detail below, may be implemented in any of numerous ways, as the disclosed concepts and embodiments are not limited to any one implementation. In addition, some aspects of the present disclosure may be used alone, or in any suitable combination with other aspects of the present disclosure.

Referring to fig. 1 and 2, the present invention aims to provide a process for reducing the loss of the opening area ratio of a microchannel plate plated with a metal film, wherein a composite metal film is evaporated on the input surface and the inner wall of the microchannel plate at a certain depth, so that the requirements of the surface resistance technical indexes are met, and the problems of the traditional plate that the thickness is too thick and the loss of the opening area ratio is large are avoided.

Referring to fig. 2, the invention theoretically calculates the ratio of the area of the opening of the microchannel plate affected by the coating, constructs an ideal model, sets the chamfer angle to 0 degree for convenient calculation, and the ratio of the area of the opening when the coating is not coated is as follows as shown in fig. 2:

considering the influence of the thickness of the film layer coated on the position, close to the input surface, of the inner wall of the channel on the aperture, the ratio of the opening area is as follows:

wherein the meaning of each parameter is as follows:

d: hole spacing

R: pore diameter

xR: depth of coated electrode (aperture R as unit)

θ: included angle between input surface of microchannel plate and incident particle beam

A: microchannel plate input mask layer thickness

V: when theta is 90, the film deposition rate

From the model constructed by the invention, the influence of the thickness of the coating film and the depth of the coating film on the loss of the ratio of the opening area is very large.

The invention discloses a method for reducing the specific loss of an opening area after plating a metal film on a microchannel plate. For example, the coating process is optimized by focusing the light spot of an electron gun and additionally arranging an evaporation rate selection device, so that the aims of denser nickel-chromium alloy film layer evaporated on the input surface of the microchannel plate and smaller resistivity than the film layer before improvement are fulfilled. Then, a layer of 10nm metal silver or copper is evaporated on the surface of the nickel-chromium alloy film layer to increase the electrical conductivity of the input surface, and finally a layer of nickel-chromium alloy film layer is plated. Because the resistivity of the metal silver or copper is far less than that of the nickel-chromium alloy, on the premise of meeting the requirement of the input surface resistance, compared with the prior art, the thickness of the whole film layer can be reduced, and the purpose of reducing the specific loss of the opening area after the metal film layer is plated on the microchannel plate is achieved.

If the metal silver/copper material is directly plated on the input end face, the reflectivity of the input end face to incident light is influenced, part of light passing through the cathode film layer is reflected by the electrode of the input end face to cause stray condition, and signal crosstalk influences the whole imaging effect of the image tube, so that a 20nm nickel-chromium alloy film layer is evaporated on the surface of the metal silver or copper film layer, the conductive film layer of the input face is ensured not to influence other performances of the microchannel plate, and the composite film layer with an ABA (absorption enhancement mode) sequential laminated structure is adopted in the implementation process of the invention.

In an alternative example, a coating rate selection device is installed and placed on the coating material, and because the crucible for placing the coating material is a fixed size designed by an equipment manufacturer, the baffle can be opened for evaporation after the coating material is pre-melted by using an electron gun each time. Because the size of electron facula is less than the size of coating material far away, coating material surface temperature is the gradient distribution that center height is low on the edge: the central temperature of the coating material is high, the energy of evaporated atoms or clusters is high, the density of a film layer formed by deposition on a substrate is good, and the resistivity is low; the edge temperature of the coating material is low, the energy of evaporated atoms or clusters is low, and the coating layer deposited on the substrate has poor density and high resistivity. For the practice of the present invention, the higher the energy of the film-forming material, the better the film-forming state. Under the condition that the inherent influence of different speeds of coating materials generated by a coating machine cannot be avoided, a coating selection device is additionally designed on the basis of a conventional coating machine, as an optional embodiment, the coating selection device is provided with an aluminum plate which is provided with a hole and is placed above a crucible, the hole is over against a coating material facula area, and a coating material evaporation area is selected by using the hole, so that atoms/clusters evaporated at a low-temperature area at the edge of the coating material cannot reach a substrate, the energy of the coating material atoms/clusters reaching the substrate is improved, the quality of an evaporated film layer is better, and the resistivity is reduced.

In the method for improving the resolution of the microchannel plate and the evaporation method thereof in the prior art, materials such as metal silver and the like are directly plated on the input end face, which can affect the reflectivity of the input end face to incident light, and part of light passing through the cathode film layer is reflected by an electrode of the input end face to cause stray condition and signal crosstalk to affect the imaging effect of the whole image tube; meanwhile, the input end face is directly added with a metal material without changing the nickel-chromium alloy film coating process of the input end face, the purpose of reducing the loss amount of the opening area ratio cannot be achieved, on the contrary, the loss of the opening area ratio is more due to the addition of the coating film, and therefore the problem of reducing the loss amount of the opening area ratio of the input face of the microchannel plate, which is aimed at by the patent application, cannot be directly or indirectly solved.

As an alternative embodiment, the present invention generally provides a process for reducing loss of an open area ratio in a process of preparing a composite metal film layer in a microchannel plate channel array, comprising the steps of: providing a substrate with a densely arranged circular micropore array; and in a vacuum environment, overlapping the circular micropore input surface of the circular micropore array and the inner wall with a certain depth by adopting a mode of sequentially evaporating two materials to form a sequential laminated structure ABA, wherein the layer A is a nickel-chromium alloy layer, and the layer B is a metal silver or copper layer.

Wherein the thickness of the layer A is 2 times of that of the layer B.

Wherein, the thickness of the A layer is 20nm, and the thickness of the B layer is 10 nm.

Wherein, the diameter of the circular micropore in the circular micropore array is phi 6um, and the hole interval between the adjacent circular micropore is 7.5um, and the length of circular micropore is 0.33 mm. The dimensions of the microchannel plate were phi 25 mm.

In an alternative embodiment, the specific preparation steps of the foregoing process include:

providing a substrate of a densely arranged circular micropore array, cleaning, drying, and placing on a tool rack in a vacuum coating machine;

vacuumizing to make the vacuum degree in the vacuum coating machine reach 1 x 10^-1Pa, carrying out vacuum baking on the substrate at the temperature of 200 ℃;

starting the evaporation of the nickel-chromium alloy film layer after baking;

after the evaporation of the nickel-chromium alloy film layer is finished, rotating the coating material crucible, and starting the evaporation of the metal silver or copper film layer;

after the evaporation of the metallic silver or copper film layer is finished, rotating the coating material crucible again, and starting the evaporation of the nickel-chromium alloy film layer;

and in the evaporation process, the thickness of each film layer of the ABA sequential laminated structure is controlled within a preset range.

The following description is made with reference to specific examples.

[1] Making a Material layer A

[1.1]Placing the cleaned substrate on a planetary tool rack of a vacuum coating machine, starting to vacuumize until the vacuum degree reaches 1 x 10^-1Pa, carrying out vacuum baking on the substrate at the temperature of 200 ℃;

(1.2) starting evaporation plating of a nickel-chromium alloy film layer after baking is finished, wherein the thickness is accurately controlled by a film thickness meter;

[2] making a layer of material B

After the evaporation of the nickel-chromium alloy film layer is finished, rotating the coating material crucible, starting the evaporation of the metal silver or copper film layer, and accurately controlling the thickness by a film thickness meter;

[3] making a Material layer A

After the evaporation of the metal silver or copper film layer is finished, the crucible for coating the film material is rotated, the evaporation of the nickel-chromium alloy film layer is started, and the thickness is accurately controlled by a film thickness meter.

In an optional embodiment, the coating equipment selects an electron beam evaporation type vacuum coating machine, and the tool is adjusted to ensure that the evaporation angle of the film layer meets the requirement of the coverage depth of the film layer on the inner wall of the element channel.

[1] Checking whether the surface of the cleaned substrate is qualified or not, loading the substrate into a coating fixture after the surface is qualified, then loading the coating fixture with the substrate into an adjusted coating fixture, and closing a cavity door and vacuumizing after the substrate is checked to be correct;

[2]installing a coating speed selecting device, wherein the device is placed on a coating material, and because a crucible for placing the coating material is a fixed size designed by an equipment manufacturer, the coating material is pre-melted by using an electron gun every time and then a baffle is opened for evaporation. Because the size of the electron facula is far smaller than that of the coating material, the evaporation rate of the surface of the coating material is inconsistent, the evaporation rate is smaller towards the edge, the energy of the material reaching the substrate for film formation is smaller, and early tests prove that the material reaches the substrate for film formationThe larger the energy of the film-forming material is, the better the film-forming state of the product is. The coating speed selecting device is designed to avoid the inherent influence of different coating speeds of the coating materials generated by a coating machine, the coating speed selecting device adopts an aluminum plate to open a hole, the hole is opposite to the coating materials, the size of the hole depends on the speed of the coating materials to be selected and go out from the coating materials, and the size of the hole is determined to be 176mm finally²(the surface area of the coating material was 1256mm²) Thereby achieving the purpose of selecting different coating rates and ensuring that the quality of the evaporated film is better.

[3]Vacuum degree up to 1.0 x 10^-1Baking the substrate at 200 ℃ when the pressure is Pa, wherein a vacuum system normally works in the baking process;

[4] making a Material layer A

[1.1]After the baking is finished, the spot size of the electron gun is adjusted to 12mm²When the beam current reaches 500mA, the nickel-chromium alloy plating material can be evaporated, and the speed in the evaporation process is controlled to be 3nm/s-5 nm/s;

(1.2) evaporating a nickel-chromium alloy film layer, wherein the thickness of 20nm is accurately controlled by a film thickness meter;

[2] making a layer of material B

After the evaporation of the nickel-chromium alloy film layer is finished, rotating the coating material crucible, starting the evaporation of the metal silver or copper film layer, and accurately controlling the thickness of 10nm by a film thickness meter;

[3] making a Material layer A

After the evaporation of the metallic silver or copper film layer is finished, the crucible for coating the film material is rotated, the evaporation of the nickel-chromium alloy film layer is started, and the thickness of 20nm is accurately controlled by a film thickness meter. Deflating the cavity after waiting for 10 minutes; and taking out the substrate after the air release is finished, and finishing the preparation process.

The film prepared by the method of the invention has the advantages that the surface resistance meets the technical index requirement, the thickness of the film is reduced by 150nm compared with the thickness of the film prepared by the original normal process (200nm), and the loss of the opening area ratio of the input surface of the microchannel plate is reduced to 2 percent from 4.8 percent, thereby effectively reducing the loss.

Although the present invention has been described with reference to the preferred embodiments, it is not intended to be limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the invention. Therefore, the protection scope of the present invention should be determined by the appended claims.