Method for controlling thickness of multi-layer film

Abstract

The invention provides a multi-layer film thickness control method which is based on a vacuum coating machine, and the vacuum coating machine comprises an evaporation system, an umbrella stand and a correction plate located between the evaporation system and the umbrella stand; the correction plates comprise a first correction plate, a second correction plate and a third correction plate; the method mainly comprises the following steps: firstly, placing a substrate glass product in a clamp, then placing the clamp in a hollow part of an umbrella stand, starting an evaporation source, driving an electron beam into a coating material, enabling the coating material to be evaporated by the electron beam and then penetrate through a first correction plate to be deposited on the surface of the substrate glass product, and then closing the evaporation source of an evaporation system to finish first coating; replacing the first correction plate with a second correction plate, and carrying out second coating; and finally, replacing the second correction plate with a third correction plate, and carrying out third coating. The method is reasonable in conception and simple in process, the uniformity of product coating can be effectively controlled, the performance and the yield of products are remarkably improved, the coating material loss is low, and the requirement for coating products with higher precision can be met.

Description

Technical Field

[0001] The invention relates to the field of optoelectronic technology, and in particular to a method for controlling the thickness of a multilayer film. Background Art

[0002] For multi-layer thin film filters, the A side is used for filtering, and the number of layers is generally more than 40, and the thickness is more than 5um, such as coating infrared cut-off film, narrow-band film, dual-channel film, etc.; the B side is used for general anti-reflection, usually about 10 layers, with a thickness of about 0.3um, and the largest generally does not exceed 0.5um. Due to the large difference in the thickness of the film on the A side and the B side (for example: the thickness of 50um on the A side is 10 times the thickness of 0.5um on the B side), after the substrate is plated, the product will be severely warped: the thicker A side will "arch". In the film formation process, as the thickness of the thin film deposition increases, this "arching" will become more serious, resulting in uneven film in the "arched" point area and the surrounding area of ​​the product.

[0003] Take a glass substrate with a thickness of 0.21 as an example, and a size of 77mm*77mm, to make an infrared cut-off filter: 45 layers of infrared cut-off film are made on the A side, with a thickness of about 5um; 7 layers of visible light anti-reflection film are made on the B side, with a thickness of about 0.3um. After the product is plated, the A side is "arched" with a height of about 3mm.

[0004] For a 1.5-meter coating machine, the distance from the evaporation source to the position of the substrate directly above is about 1000mm; when the A surface is about to be coated, the distance between the "arched" point and the evaporation point increases to 1003mm. The evaporation source is regarded as a point light source, emitting light at a certain divergence angle, and the vertical axis of the line connecting the substrate and the evaporation source is horizontal, and the substrate is placed horizontally on the umbrella stand. Let a represent the film thickness obtained at a distance of 1000mm (product edge), and b represent the film thickness obtained at a distance of 1003mm (the "arched" point). According to the basic formula of object illumination, a:b=(1003:1000) 2 ≈1.006, that is, after the film is arched up by 3mm, the film thickness decreases by 0.6%; that is, during the entire coating process, the non-uniformity of the product center point gradually increases from 0 to 0.6%, and the average non-uniformity of the center point is (0+0.6%) / 2=0.3%. In many multi-layer thin film systems with high sensitivity, the impact of this 0.3% is sometimes fatal.

[0005] The existing technology usually completes the plating in one go, and its advantage is high efficiency. However, this "natural" 0.3% non-uniformity cannot be eliminated. For some sensitive film systems, sometimes only 0.3% uniformity is allowed at most. Coupled with the influence of other factors, the overall uniformity error is 0.5%~1.0%. In this way, the performance of good products cannot be guaranteed. In the actual production process, some manufacturers cannot determine how many good performance products are in a furnace, and can only perform 100% full inspection after plating. Only those that meet the performance standards will flow to the next workstation. This will cause relatively high losses and high uncertainty, making it difficult to control in actual production.

[0006] To sum up, it is necessary to make further innovations on existing technologies. Summary of the invention

[0007] In response to the technical problems existing in the above-mentioned background technology, the present invention proposes a method for controlling the thickness of a multi-layer film. The method has a reasonable concept and a simple process, can effectively control the uniformity of the product coating, significantly improve the performance and yield of the product, has low loss of coating material, and can meet the requirements of higher precision coating products.

[0008] In order to solve the above technical problems, the present invention provides a method for controlling the thickness of a multilayer film, based on a vacuum coating machine, wherein the vacuum coating machine includes an evaporation system, an umbrella stand matched and located directly above the evaporation system, and a correction plate matched and located between the evaporation system and the umbrella stand; the correction plates include a first correction plate, a second correction plate, and a third correction plate; the method mainly includes the following steps: (1) firstly placing the substrate glass product in the fixture of the vacuum coating machine, and then placing the fixture on the hollow part of the umbrella frame, starting the evaporation source of the evaporation system, and injecting the electron beam into the coating material, so that the coating material is evaporated by the electron beam and then passes through the first correction plate and is deposited on the surface of the substrate glass product, and then the evaporation source of the evaporation system is turned off to complete the first coating; (2) replacing the first correction plate with the second correction plate, with the edge of the second correction plate being concave relative to the edge of the first correction plate, restarting the evaporation source of the evaporation system, injecting the electron beam into the coating material, so that the coating material is evaporated by the electron beam and then passes through the second correction plate and is deposited again on the surface of the substrate glass product, and then shutting down the evaporation source of the evaporation system to complete the second coating; (3) The second correction plate is replaced by the third correction plate, and the edge of the third correction plate is concave relative to the edge of the second correction plate. The evaporation source of the evaporation system is started again, and the electron beam is injected into the coating material, so that the coating material is evaporated by the electron beam and then passes through the third correction plate and is deposited again on the surface of the substrate glass product. Then, the evaporation source of the evaporation system is turned off to complete the third coating.

[0009] The method for controlling the thickness of the multi-layer film, wherein: before the start of coating, the planes of the first revised version, the second revised version and the third revised version must be divided to ensure that the coating material at the most middle position of the first revised version, the second revised version and the third revised version is the largest during coating, and to ensure that the coating material at the two sides of the most middle position decreases in sequence relative to the middle position.

[0010] The method for controlling the thickness of a multi-layer film, wherein: when the planes of the first revised version, the second revised version and the third revised version are divided, the thickness deviation of adjacent positions is controlled within 0.5%.

[0011] The method for controlling the thickness of a multilayer film, wherein: in the step (1), when the glass substrate product is coated for the first time, the coating temperature is between 120°C and 180°C, and the vacuum degree at the beginning of coating is between 1.0E-3 and 3.0E-3; during the first coating process, when coating a high refractive index material, the vacuum degree is between 1.5E-2 and 2.5E-2; during the first coating process, when coating a low refractive index material, the vacuum degree is between 1.0E-2 and 2.0E-2; after the first coating, the center of the substrate glass product is arched by 1 mm; at this time, the center point non-uniformity of the substrate glass product increases from 0 to 0.2%, and after the first coating of the substrate glass product, the average center point non-uniformity is 0.1%.

[0012] The method for controlling the thickness of a multilayer film, wherein: in the step (2), when the glass substrate product is coated for the second time, the coating temperature is between 120 and 180° C.; the vacuum degree at the start of coating is between 1.0E-3 and 3.0E-3; during the second coating process, when coating a high refractive index material, the vacuum degree is between 1.5E-2 and 2.5E-2; during the second coating process, when coating a low refractive index material, the vacuum degree is between 1.0E-2 and 2.0E-2; after the second coating, the center arch height of the substrate glass product increases to 2 mm, at which time the product center point non-uniformity increases from 0 to 0.2%, and after the substrate glass product is coated for the second time, the average center point non-uniformity of the substrate glass product is 0.1%.

[0013] The method for controlling the thickness of a multi-layer film, wherein: in the step (2), the edge of the second revised plate is recessed by 0.2 mm to 2.0 mm relative to the edge of the first revised plate.

[0014] The method for controlling the thickness of a multilayer film, wherein: in the step (3), when the glass substrate product is coated for the third time, the coating temperature is between 120 and 180° C., and the vacuum degree at the start of coating is between 1.0E-3 and 3.0E-3; during the third coating process, when coating a high refractive index material, the vacuum degree is between 1.5E-2 and 2.5E-2; during the third coating process, when coating a low refractive index material, the vacuum degree is between 1.0E-2 and 2.0E-2; after the third coating, the center arch height of the substrate glass product increases to 3 mm, at which time the center point non-uniformity of the substrate glass product increases from 0 to 0.2%, and after the substrate glass product is coated, the average center point non-uniformity of the substrate glass product is 0.1%.

[0015] The method for controlling the thickness of a multi-layer film, wherein: in the step (3), the edge of the third revised version is also recessed by 0.2 mm to 2.0 mm relative to the edge of the second revised version.

[0016] The method for controlling the thickness of a multi-layer film, wherein: the electron beam of the evaporation source of the evaporation system is injected into the coating material with a power of 5000W-8000W.

[0017] The method for controlling the thickness of a multi-layer film, wherein: the evaporation source of the evaporation system is matched and placed at a position 1000m away from the center point of the umbrella frame.

[0018] By adopting the above technical solution, the present invention has the following beneficial effects: The multi-layer film thickness control method of the present invention has a reasonable concept and a simple process. It can effectively control the uniformity of the product coating by plating three times through a layer of thin film system, significantly improve the performance and yield of the product, and has low loss of coating material, which can meet the needs of higher precision coating products.

[0019] The present invention can reduce the non-uniformity of product coating from 0.3% to 0.1%. In some narrow-band filter coatings, some high-requirement thin films require 0.1% uniformity, which generally requires direct light control. The present invention can achieve this with indirect light control, reducing the increased cost and modification of coating equipment caused by direct light control. In addition, even if a high-precision control method is used, the larger the area of ​​the optical element, the more uniform the midpoint and edge cannot be taken into account. The present invention can effectively solve this problem and increase the use area of ​​the optical element. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 A diagram showing the local structural position of a vacuum coating machine involved in the method for controlling the thickness of a multi-layer film of the present invention; Figure 2 A state diagram of a substrate glass product involved in the method for controlling the thickness of a multi-layer film of the present invention being loaded on an umbrella stand; Figure 3 A top view of a revised version of the method for controlling the thickness of a multi-layer film of the present invention; Figure 4 It is a schematic diagram of the structural state of the first revision plate and the coated product during the first coating in the method for controlling the thickness of a multi-layer film of the present invention; Figure 5 It is a schematic diagram of the structural state of the second revision plate and the coated product during the second coating in the method for controlling the thickness of the multi-layer film of the present invention; Figure 6 It is a schematic diagram of the structural status of the third revision plate and the coated product during the third coating in the method for controlling the thickness of the multi-layer film of the present invention. DETAILED DESCRIPTION

[0022] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] The present invention is further explained below in conjunction with specific implementation modes.

[0024] like Figure 1 As shown, a method for controlling the thickness of a multi-layer film provided in this embodiment is based on a vacuum coating machine, which includes an evaporation system, an umbrella frame 2 matched to be located directly above the evaporation system, and a correction plate 4 matched to be located between the evaporation system and the umbrella frame 2; the correction plate 4 includes a first correction plate, a second correction plate and a third correction plate.

[0025] This embodiment is to plate 45 layers of coating in three times, specifically including the following steps: S100, first coating First, place the substrate glass product 1 in the fixture of the vacuum coating machine, and then place the fixture on the hollow part of the umbrella frame 2 (such as Figure 2 As shown), the evaporation source 3 of the evaporation system is placed 1000m away from the center point of the umbrella stand 2; Figure 1 and Figure 3 , the plane of the first revised version is divided into seven areas, namely 1#-7# positions for correction. The coating material at 4# position of the first revised version is the largest, and the coating material at 3#-1# positions of the first revised version decreases in sequence, and the coating material at 4#-7# positions of the first revised version decreases in sequence; therefore, the area blocked by 4# position of the first revised version is the largest, and the areas at other positions decrease in sequence; through this method of the first revised version, the thickness of the coating material at 1#-7# positions tends to be consistent, and the thickness deviation is controlled within 0.5%; 15 layers of coating: Figure 1 As shown, the evaporation source 3 of the evaporation system is started, and the electron beam is driven into the coating material with a certain energy (5000W-8000W). After the coating material is evaporated by the electron beam, it is deposited on the surface of the substrate glass product 1, and then the evaporation source 3 of the evaporation system is closed; wherein, during the first coating, the coating temperature is between 120°C and 180°C, and the vacuum degree of the coating is between 1.0E-3 and 3.0E-3; during the first coating process, when the high refractive index material is coated, the vacuum degree is between 1.5E-2 and 2.5E-2; during the first coating process, when the low refractive index material is coated, the vacuum degree is between 1.0E-2 and 2.0E-2; after the first coating, the center of the substrate glass product 1 is arched by 1mm; at this time, the center point non-uniformity of the substrate glass product 1 increases from 0 to 0.2%. After the substrate glass product 1 is coated, the average center point non-uniformity of the substrate glass product 1 is (0+0.2%) / 2=0.1%, that is, the average uniformity of the first 15 layers is 0.1%.

[0026] The average value of the non-uniformity of the center point of the substrate glass product 1 is mainly calculated according to the illumination formula. The illumination is inversely proportional to the square of the light source distance. The evaporation source 3 is regarded as a light source. The calculation is performed according to this formula: Figure 1, for a 1.5-meter coating machine, the distance from the evaporation source 3 to the position of the substrate glass just above is about 1000mm; when the A surface of the substrate glass product 1 is about to be coated, the distance between the "arched" point of the substrate glass product 1 and the evaporation point increases to 1003mm. Consider the evaporation source 3 as a point light source, emitting light at a certain divergence angle, and the movement direction of the evaporated coating material is perpendicular to the surface of the substrate glass product 1, and the substrate glass product 1 is placed horizontally on the umbrella stand 2; let a represent the film thickness obtained at a distance of 1000mm (the edge of the substrate glass product 1), and b represent the film thickness obtained at a distance of 1003mm, i.e., the arched point. According to the basic formula of object illumination, a:b=(1003:1000)2≈1.006, i.e., after arching 3mm (such as Figure 4 As shown in the figure, the film thickness decreases by 0.6%; that is, during the entire coating process, the non-uniformity of the center point of the substrate glass product 1 gradually increases from 0 to 0.6%, and the average non-uniformity of the center point of the substrate glass product 1 is (0+0.6%) / 2=0.3%. In many multi-layer thin film systems with relatively high sensitivity, the impact of this 0.3% is sometimes fatal.

[0027] S200, Second Coating Replace the first revision plate with the second revision plate (different in shape from the first revision plate), and make corrections to the substrate glass product 1 according to the 1mm arch height produced by the first coating (such as Figure 5 As shown in the figure, the plane of the second revised version is divided into seven areas. The edges of the 1#~7# positions of the second revised version are "concave inward" relative to the first revised version. The reason is that the product is arched and receives about 0.1% less coating material. Therefore, the edges of the second revised version (i.e., the seven areas) are concave inward by 0.2mm~2.0mm relative to the edges of the first revised version, so that the center point of each area obtains "more" coating material, thereby balancing the 0.1% unevenness.

[0028] 15 layers of coating: Figure 1, start the evaporation source 3 of the evaporation system, and inject the electron beam into the coating material with a certain energy (5000W-8000W); after the coating material is evaporated by the electron beam, it is deposited on the surface of the substrate glass product 1, and then the evaporation source 3 of the evaporation system is closed; during the second coating, the coating temperature is between 120~180℃, and the vacuum degree is between 1.0E-3~3.0E-3; during the second coating process, when coating high refractive index materials, the vacuum degree is between 1.5E-2~2.5E-2; during the second coating During the coating process, when coating low refractive index materials, the vacuum degree is between 1.0E-2 and 2.0E-2; after the second coating, the center point arch height of substrate glass product 1 increases by 1mm, that is, the arch height of the product increases to 2mm. At this time, the center point non-uniformity of substrate glass product 1 increases from 0 to 0.2%. After the second coating of substrate glass product 1, the average center point non-uniformity of substrate glass product 1 is (0+0.2%) / 2=0.1%, that is, the average uniformity of the middle 15 layers is 0.1%. The second revised version is corrected according to the current state of the center point arch of substrate glass product 1, and the center point arch height of substrate glass product 1 increases with the increase of the number of coating layers, but the revised version cannot follow it. Therefore, assuming that the uniformity of the revised version in the initial state is 0%, after coating these 15 layers, due to the increase in glass arch height and the lack of a cover plate on the revised version, the instantaneous uniformity is 0.2%; that is, the uniformity increases gradually from 0 to 0.2% to a certain extent.

[0029] S300, the third coating The second revised version is replaced with the third revised version (the shape is different from the first and second revised versions), and the center point of the substrate glass product 1 is corrected according to the 1mm arch height generated by the second coating; the plane of the third revised version is divided into seven areas, and the edges of the 1#~7# positions of the third revised version are concave 0.2mm~2.0mm relative to the second revised version.

[0030] Coating 15 layers of film: Start the evaporation source 3 of the evaporation system, and the electron beam is driven into the coating material with a certain energy (5000W-8000W); the coating material is evaporated by the electron beam and deposited on the surface of the substrate glass product 1, and then the evaporation source 3 of the evaporation system is closed. Among them, during the third coating, the coating temperature is 120~180℃, and the vacuum degree at the beginning of coating is between 1.0E-3~3.0E-3; during the third coating process, when coating high refractive index materials, the vacuum degree is between 1.5E-2~2.5E-2; during the third coating process, when coating low refractive index materials, the vacuum degree is between 1.0E-2~2.0E-2; after the third coating, the center point arch height of the substrate glass product 1 increases by 1mm, that is, the arch height of the product increases to 3mm (such as Figure 6As shown in the figure), at this time, the center point non-uniformity of the substrate glass product 1 increases from 0 to 0.2%. After the substrate glass product 1 is plated, the average center point non-uniformity of the substrate glass product 1 is (0+0.2%) / 2=0.1%, that is, the average uniformity of the last 15 layers is 0.1%.

[0031] Among them, since the average uniformity of the first 15 layers, the middle 15 layers and the last 15 layers is 0.1%, that is, the uniformity of the entire film system is controlled at 0.1%; through the method of the present invention, the non-uniformity is reduced from 0.3% to 0.1%.

[0032] The present invention has a reasonable concept and a simple process. It can effectively control the uniformity of product coating by plating three times through a thin film system, significantly improve product performance and yield, and has low loss of coating material, which can meet the needs of coating products with higher precision.

[0033] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for controlling the thickness of a multilayer film, based on a vacuum coating machine, wherein the vacuum coating machine comprises an evaporation system, an umbrella frame matched and located directly above the evaporation system, and a correction plate matched and located between the evaporation system and the umbrella frame; the correction plate comprises a first correction plate, a second correction plate and a third correction plate; characterized in that: The main steps include: (1) firstly placing the substrate glass product in the fixture of the vacuum coating machine, and then placing the fixture on the hollow part of the umbrella frame, starting the evaporation source of the evaporation system, and injecting the electron beam into the coating material, so that the coating material is evaporated by the electron beam and then passes through the first correction plate and is deposited on the surface of the substrate glass product, and then the evaporation source of the evaporation system is turned off to complete the first coating; (2) replacing the first correction plate with the second correction plate, with the edge of the second correction plate being concave relative to the edge of the first correction plate, restarting the evaporation source of the evaporation system, injecting the electron beam into the coating material, so that the coating material is evaporated by the electron beam and then passes through the second correction plate and is deposited again on the surface of the substrate glass product, and then shutting down the evaporation source of the evaporation system to complete the second coating; (3) The second correction plate is replaced by the third correction plate, and the edge of the third correction plate is concave relative to the edge of the second correction plate. The evaporation source of the evaporation system is started again, and the electron beam is injected into the coating material, so that the coating material is evaporated by the electron beam and then passes through the third correction plate and is deposited again on the surface of the substrate glass product. Then, the evaporation source of the evaporation system is turned off to complete the third coating.

2. The method for controlling the thickness of a multilayer film according to claim 1, characterized in that: Before coating begins, the planes of the first revised version, the second revised version and the third revised version must be divided to ensure that the coating material at the middle position of the first revised version, the second revised version and the third revised version is the largest during coating, and to ensure that the coating material at the two sides of the middle position decreases in sequence relative to the middle position.

3. The method for controlling the thickness of a multilayer film according to claim 2, wherein: When the planes of the first revised version, the second revised version and the third revised version are divided, the thickness deviation of adjacent positions is controlled within 0.5%.

4. The method for controlling the thickness of a multilayer film according to claim 1, wherein: In the step (1), when the glass substrate product is coated for the first time, the coating temperature is between 120° C. and 180° C., and the vacuum degree at the beginning of coating is between 1.0E-3 and 3.0E-3; during the first coating process, when coating a high refractive index material, the vacuum degree is between 1.5E-2 and 2.5E-2; during the first coating process, when coating a low refractive index material, the vacuum degree is between 1.0E-2 and 2.0E-2; after the first coating, the center of the substrate glass product is arched by 1 mm; at this time, the center point non-uniformity of the substrate glass product increases from 0 to 0.2%, and after the first coating of the substrate glass product, the average center point non-uniformity is 0.1%.

5. The method for controlling the thickness of a multilayer film according to claim 1, wherein: In the step (2), when the glass substrate product is coated for the second time, the coating temperature is between 120 and 180° C.; the vacuum degree at the start of coating is between 1.0E-3 and 3.0E-3; during the second coating process, when coating a high refractive index material, the vacuum degree is between 1.5E-2 and 2.5E-2; during the second coating process, when coating a low refractive index material, the vacuum degree is between 1.0E-2 and 2.0E-2; after the second coating, the center arch height of the substrate glass product increases to 2 mm, and at this time, the center point non-uniformity of the product increases from 0 to 0.2%. After the second coating of the substrate glass product, the average center point non-uniformity of the substrate glass product is 0.1%.

6. The method for controlling the thickness of a multilayer film according to claim 1, wherein: In the step (2), the edge of the second revised version is recessed by 0.2 mm to 2.0 mm relative to the edge of the first revised version.

7. The method for controlling the thickness of a multilayer film according to claim 1, wherein: In the step (3), when the glass substrate product is coated for the third time, the coating temperature is between 120 and 180° C., and the vacuum degree at the beginning of coating is between 1.0E-3 and 3.0E-3; during the third coating process, when coating a high refractive index material, the vacuum degree is between 1.5E-2 and 2.5E-2; during the third coating process, when coating a low refractive index material, the vacuum degree is between 1.0E-2 and 2.0E-2; after the third coating, the center arch height of the substrate glass product increases to 3 mm, and at this time, the center point non-uniformity of the substrate glass product increases from 0 to 0.2%. After the substrate glass product is coated, the average center point non-uniformity of the substrate glass product is 0.1%.

8. The method for controlling the thickness of a multilayer film according to claim 1, wherein: In the step (3), the edge of the third revised version is also recessed by 0.2 mm to 2.0 mm relative to the edge of the second revised version.

9. The method for controlling the thickness of a multi-layer film according to claim 1, wherein: The electron beam of the evaporation source of the evaporation system is injected into the coating material with a power of 5000W-8000W.

10. The method for controlling the thickness of a multi-layer film according to claim 1, wherein: The evaporation source of the evaporation system is matched and placed at a position 1000m away from the center point of the umbrella stand.

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