Wave infrared durable antireflection film in silicon window and preparation method thereof

Abstract

The invention relates to the field of film preparation, in particular to a silicon window middle-wave infrared durable antireflection film and a preparation method thereof. The silicon window middle-wave infrared durable antireflection film comprises a base layer, a middle layer and a wear-resistant hardening layer, the middle layer and the wear-resistant hardening layer are arranged on the two sides of the base layer, the middle layer is located between the base layer and the wear-resistant hardening layer, the base layer is a silicon window, and the wear-resistant hardening layer is located between the middle layer and the wear-resistant hardening layer. The middle layer sequentially comprises a first germanium layer, a first zinc sulfide layer, a second germanium layer, a second zinc sulfide layer and an ytterbium fluoride layer; the wear-resistant hardening layer sequentially comprises an yttrium oxide layer and a silicon dioxide layer; the method comprises the following steps: S1, cleaning a silicon window sheet to be coated, and placing the silicon window sheet in a cavity of a coating machine, and S2, starting an argon ion source to clean the silicon window sheet after the background vacuum of the cavity meets the requirement; s3, a first germanium layer, a first zinc sulfide layer, a second germanium layer, a second zinc sulfide layer, an ytterbium fluoride layer, an yttrium oxide layer and a silicon dioxide layer are sequentially evaporated on the surface of the silicon window piece; and S4, the other side of the silicon window piece is sequentially coated with films.

Description

Technical Field

[0001] The present application relates to the technical field of infrared coating, and specifically, to a mid-wave infrared durable antireflection film for silicon wafers and a preparation method thereof. Background Art

[0002] In infrared optoelectronic systems, the transmittance of most infrared optical window materials is relatively low. Therefore, it is necessary to deposit an infrared antireflection film on the material surface to improve its transmittance and reduce the reflection loss on the window surface. For the windows of optoelectronic systems that are directly in contact with the atmosphere, in the harsh outdoor environmental conditions or during uncontrolled surface cleaning during field technical maintenance, it is necessary to deposit an antireflection film with wear resistance and corrosion resistance.

[0003] Depositing diamond-like films, such as germanium carbide, boron phosphide, and gallium phosphide hard protective films, on the window material surface or outside the multi-layer antireflection film can greatly improve the durability of the film layer. However, most of the processes are complex and costly, or at the expense of the window transmittance, reducing the use effect. Therefore, it is very necessary to find an infrared antireflection film that can not only play an antireflection role but also achieve a good protection effect. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the present application provides a mid-wave infrared durable antireflection film for silicon wafers and a preparation method thereof, aiming to improve the problems proposed in the above background art.

[0005] The mid-wave infrared durable antireflection film for silicon wafers provided by the embodiment of the present application includes a base layer, an intermediate layer, and a wear-resistant and hardening layer. The intermediate layer and the wear-resistant and hardening layer are both provided on both sides of the base layer. The intermediate layer is located between the base layer and the wear-resistant and hardening layer. The base layer is a silicon wafer. The intermediate layer successively includes a first germanium layer, a first zinc sulfide layer, a second germanium layer, a second zinc sulfide layer, and a ytterbium fluoride layer. The wear-resistant and hardening layer successively includes a yttrium oxide layer and a silicon dioxide layer.

[0006] Furthermore, the silicon dioxide layer is a dehydroxylated silicon dioxide layer. The dehydroxylation process helps to remove impurities in the silicon dioxide, such as hydroxyl groups, etc., thereby improving its purity. Dehydroxylated silicon dioxide is not easily reactive with any acid except hydrofluoric acid and phosphoric acid. Dehydroxylated silicon dioxide can maintain stable performance in a high-temperature environment, is not easily deformed, and exhibits good chemical stability.

[0007] Furthermore, the thickness of the first germanium layer is 30 - 35 nm, the thickness of the first zinc sulfide layer is 165 - 175 nm, the thickness of the second germanium layer is 30 - 35 nm, the thickness of the second zinc sulfide layer is 190 - 210 nm, the thickness of the ytterbium fluoride layer is 420 - 480 nm, the thickness of the yttrium oxide layer is 30 - 50 nm, and the thickness of the silicon dioxide layer is 50 - 70 nm.

[0008] Meanwhile, the present invention also provides a method for preparing the mid-wave infrared durable antireflection film on the silicon window pane as described above, comprising the following steps: S1 After cleaning the silicon window pane to be coated, place it in the cavity of the coating machine, start the vacuum pumping system of the coating machine, and set the cavity baking temperature to 125 - 135 °C; Usually, corresponding cleaning treatment is required before coating the silicon window pane to avoid impurities on the silicon window pane affecting the coating quality and ultimately the performance of the product; S2 After the base vacuum of the cavity reaches 6.0E-4 Pa, start the argon ion source to clean the silicon window pane for 10 min. The ion source neutralization current is 0.5 A, the neutralizing gas flow rate is 8 sccm, the anode voltage is 150 V, the anode current is 2 A, and the argon gas flow rate is 100%; S3 Evaporate a first germanium layer, a first zinc sulfide layer, a second germanium layer, a second zinc sulfide layer, a ytterbium fluoride layer, a yttrium oxide layer, and a silicon dioxide layer on the surface of the silicon window pane in sequence; S4 Repeat steps 1 - 3 to deposit the film layers on the other side of the silicon window pane in sequence.

[0009] Furthermore, the germanium layer, the yttrium oxide layer, and the silicon dioxide layer are prepared by electron beam evaporation process; In the coating chamber with high vacuum, the evaporated atoms or molecules are precisely guided to the surface of the silicon window pane and form a dense thin film there. Since the process is carried out in vacuum, these atoms or molecules hardly interact with other gas molecules, ensuring the formation of high-quality thin films.

[0010] Furthermore, the zinc sulfide layer and the ytterbium fluoride layer are prepared by resistance heating evaporation process; The resistance heating evaporation process has the advantages of simple structure and low cost, and is suitable for preparing the zinc sulfide layer and the ytterbium fluoride layer thin films.

[0011] Furthermore, the germanium layer, the zinc sulfide layer, the yttrium oxide layer, and the silicon dioxide layer are all deposited by ion-assisted plating; Ion-assisted plating is an auxiliary deposition method developed on the basis of vacuum thermal evaporation. When the film material evaporates from the resistance heating evaporation source or the electron beam heating evaporation source, the deposited molecules or atoms (deposited particles) are continuously bombarded by the energetic ions from the ion source on the surface of the substrate. Through momentum transfer, the deposited particles obtain greater kinetic energy. This simple process has fundamentally changed the film growth, thus improving the film performance.

[0012] Furthermore, when evaporating the germanium layer, the evaporation rate of germanium is 3 Å / s, the ion source neutralization current is 0.2 - 0.4 A, the neutralizing gas flow rate is 8 sccm, the anode voltage is 100 - 120 V, the anode current is 0.8 - 1.2 A, and the argon gas flow rate is 100%.

[0013] When evaporating the zinc sulfide layer, the evaporation rate of zinc sulfide is 6 Å / s, the neutralization current of the ion source is 0.2 - 0.4 A, the neutralizing gas flow rate is 8 sccm, the anode voltage is 100 - 120 V, the anode current is 0.8 - 1.2 A, and the argon gas flow rate is 100%. When evaporating the ytterbium fluoride layer, the evaporation rate of ytterbium fluoride is 5 Å / s, the neutralization current of the ion source is 0.2 - 0.4 A, the neutralizing gas flow rate is 8 sccm, the anode voltage is 100 - 120 V, the anode current is 0.8 - 1.2 A, and the argon gas flow rate is 100%. When evaporating the yttrium oxide layer, the evaporation rate of yttrium oxide is 2 Å / s, the neutralization current of the ion source is 0.2 - 0.4 A, the neutralizing gas flow rate is 8 sccm, the anode voltage is 100 - 120 V, the anode current is 0.8 - 1.2 A, and the argon gas flow rate is 100%. When evaporating the silicon dioxide layer, the evaporation rate of silicon dioxide is 2 Å / s, the neutralization current of the ion source is 0.7 - 0.9 A, the neutralizing gas flow rate is 8 sccm, the anode voltage is 200 - 220 V, the anode current is 3.5 - 4.5 A, and the argon gas flow rate is 100%.

[0014] The mid-wave infrared durable antireflection film for silicon window prepared by the method of the present invention: By setting a combination of yttrium oxide and silicon dioxide as the wear-resistant and hardening layer on the outer layer of the mid-wave infrared antireflection film system, and using a set of specific processes, the silicon window has the characteristics of good transmittance, wear resistance and corrosion resistance. The preparation method provided by the present invention is simple and is conducive to popularization and marketization. Description of the Drawings

[0015] Attached Figure 1 is the double-sided comprehensive transmission spectrum diagram of the mid-wave infrared durable antireflection film for silicon window described in Embodiment 1 of the present invention.

[0016] Attached Figure 2 is the double-sided comprehensive transmission spectrum diagram of the mid-wave infrared durable antireflection film for silicon window described in Embodiment 2 of the present invention. Detailed Embodiments

[0017] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present invention.

[0018] Embodiment 1, a mid-wave infrared durable antireflection film for silicon window includes a base layer, an intermediate layer and a wear-resistant and hardening layer. The intermediate layer and the wear-resistant and hardening layer are provided on both sides of the base layer. The intermediate layer is located between the base layer and the wear-resistant and hardening layer. The base layer is a silicon window. The intermediate layer successively includes a first germanium layer, a first zinc sulfide layer, a second germanium layer, a second zinc sulfide layer and a ytterbium fluoride layer. The wear-resistant and hardening layer successively includes a yttrium oxide layer and a silicon dioxide layer; The silicon dioxide layer is a dehydroxylated silicon dioxide layer.

[0019] The method for preparing the mid-wave infrared durable antireflection film on the silicon window pane described above includes the following steps: S1. After cleaning the silicon window pane to be coated, place it in the cavity of the coating machine, start the vacuum pumping system of the coating machine, and set the cavity baking temperature to 135 °C; S2. After the background vacuum of the cavity reaches 6.0E-4 Pa, start the argon ion source to clean the silicon window pane for 10 min. The ion source neutralization current is 0.5 A, the neutralizing gas flow rate is 8 sccm, the anode voltage is 150 V, the anode current is 2 A, and the argon gas flow rate is 100%; S3. Evaporate a first germanium layer with a thickness of 30 nm, a first zinc sulfide layer with a thickness of 169 nm, a second germanium layer with a thickness of 32 nm, a second zinc sulfide layer with a thickness of 200 nm, a ytterbium fluoride layer with a thickness of 425 nm, a yttrium oxide layer with a thickness of 50 nm, and a silicon dioxide layer with a thickness of 50 nm on the surface of the silicon window pane in sequence. Among them, the silicon dioxide is the dehydroxylated silicon dioxide optical coating material of GRINM Resources & Environment Technology Institute (Beijing) Co., Ltd.; When evaporating the germanium layer, the electron beam evaporation method is adopted, and the evaporation rate of germanium is 3 Å / s. The Hall ion source neutralization current is 0.3 A, the neutralizing gas flow rate is 8 sccm, the anode voltage is 110 V, the anode current is 1.2 A, and the argon gas flow rate is 100%. When evaporating the zinc sulfide layer, the molybdenum box resistance evaporation method is adopted, and the evaporation rate of zinc sulfide is 6 Å / s. The Hall ion source neutralization current is 0.3 A, the neutralizing gas flow rate is 8 sccm, the anode voltage is 110 V, the anode current is 1.2 A, and the argon gas flow rate is 100%. When evaporating the ytterbium fluoride layer, the molybdenum box resistance evaporation method is adopted, and the evaporation rate of ytterbium fluoride is 5 Å / s. The Hall ion source neutralization current is 0.3 A, the neutralizing gas flow rate is 8 sccm, the anode voltage is 110 V, the anode current is 1.2 A, and the argon gas flow rate is 100%. When evaporating the yttrium oxide layer, the electron beam evaporation method is adopted, and the evaporation rate of yttrium oxide is 2 Å / s. The Hall ion source neutralization current is 0.3 A, the neutralizing gas flow rate is 8 sccm, the anode voltage is 110 V, the anode current is 1.2 A, and the argon gas flow rate is 100%. When evaporating the silicon dioxide layer, the electron beam evaporation method is adopted, and the evaporation rate of silicon dioxide is 2 Å / s. The Hall ion source neutralization current is 0.8 A, the neutralizing gas flow rate is 8 sccm, the anode voltage is 200 V, the anode current is 4 A, and the argon gas flow rate is 100%. After the film layers are sequentially deposited, take out the silicon window pane, perform simple treatment, and wait for coating on the other side; S4. Repeat steps 1-3 to deposit film layers on the other side of the silicon window pane in sequence.

[0020] Example 2. A mid-wave infrared durable antireflection film for a silicon window pane comprises a base layer, an intermediate layer and a wear-resistant and hardening layer. The intermediate layer and the wear-resistant and hardening layer are disposed on both sides of the base layer. The intermediate layer is located between the base layer and the wear-resistant and hardening layer. The base layer is a silicon window pane. The intermediate layer sequentially comprises a first germanium layer, a first zinc sulfide layer, a second germanium layer, a second zinc sulfide layer and a ytterbium fluoride layer. The wear-resistant and hardening layer sequentially comprises a yttrium oxide layer and a silicon dioxide layer; The silicon dioxide layer is a dehydroxylated silicon dioxide layer.

[0021] The preparation method of the above-mentioned mid-wave infrared durable antireflection film for a silicon window pane comprises the following steps: S1. After cleaning the silicon window pane to be coated, place it in the cavity of a coating machine, start the vacuum pumping system of the coating machine, and set the cavity baking temperature to 130°C; S2. After the background vacuum of the cavity reaches 6.0E-4 Pa, start the argon ion source to clean the silicon window pane for 10 min. The ion source neutralization current is 0.5 A, the neutralizing gas flow rate is 8 sccm, the anode voltage is 150 V, the anode current is 2 A, and the argon gas flow rate is 100%; S3. Evaporate a first germanium layer with a thickness of 31 nm, a first zinc sulfide layer with a thickness of 170 nm, a second germanium layer with a thickness of 31 nm, a second zinc sulfide layer with a thickness of 201 nm, a ytterbium fluoride layer with a thickness of 426 nm, a yttrium oxide layer with a thickness of 40 nm and a silicon dioxide layer with a thickness of 60 nm on the surface of the silicon window pane in sequence. Among them, the silicon dioxide is the dehydroxylated silicon dioxide optical coating material of GRINM Resources & Environment Technology Institute Co., Ltd. (Beijing); When depositing the germanium layer, electron beam evaporation is used, and the evaporation rate of germanium is 3 Å / s. The neutralization current of the Hall ion source is 0.3 A, the neutralization gas flow rate is 8 sccm, the anode voltage is 110 V, the anode current is 1.2 A, and the argon gas flow rate is 100%. When depositing the zinc sulfide layer, molybdenum box resistance evaporation is used, and the evaporation rate of zinc sulfide is 6 Å / s. The neutralization current of the Hall ion source is 0.3 A, the neutralization gas flow rate is 8 sccm, the anode voltage is 110 V, the anode current is 1.2 A, and the argon gas flow rate is 100%. When depositing the ytterbium fluoride layer, molybdenum box resistance evaporation is used, and the evaporation rate of ytterbium fluoride is 5 Å / s. The neutralization current of the Hall ion source is 0.3 A, the neutralization gas flow rate is 8 sccm, the anode voltage is 110 V, the anode current is 1.2 A, and the argon gas flow rate is 100%. When depositing the yttrium oxide layer, electron beam evaporation is used, and the evaporation rate of yttrium oxide is 2 Å / s. The neutralization current of the Hall ion source is 0.3 A, the neutralization gas flow rate is 8 sccm, the anode voltage is 110 V, the anode current is 1.2 A, and the argon gas flow rate is 100%. When depositing the silicon dioxide layer, electron beam evaporation is used, and the evaporation rate of silicon dioxide is 2 Å / s. The neutralization current of the Hall ion source is 0.8 A, the neutralization gas flow rate is 8 sccm, the anode voltage is 200 V, the anode current is 4 A, and the argon gas flow rate is 100%. After the film layers are sequentially deposited, take out the silicon window chip, and after simple treatment, wait for coating on the other side; S4 Repeat steps 1 - 3 to sequentially deposit film layers on the other side of the silicon window chip; Example 3, a mid - wave infrared durable antireflection film for a silicon window chip includes a base layer, an intermediate layer, and a wear - resistant and hardening layer. The intermediate layer and the wear - resistant and hardening layer are both provided on both sides of the base layer. The intermediate layer is located between the base layer and the wear - resistant and hardening layer. The base layer is the silicon window chip. The intermediate layer sequentially includes a first germanium layer, a first zinc sulfide layer, a second germanium layer, a second zinc sulfide layer, and a ytterbium fluoride layer. The wear - resistant and hardening layer sequentially includes a yttrium oxide layer and a silicon dioxide layer; The silicon dioxide layer is a dehydroxylated silicon dioxide layer.

[0022] The preparation method of the above - mentioned mid - wave infrared durable antireflection film for a silicon window chip includes the following steps: S1, After cleaning the silicon window chip to be coated, place it in the coating machine cavity, start the coating machine vacuum pumping system, and set the cavity baking temperature to 125 °C; S2, After the background vacuum of the cavity reaches 6.0E - 4 Pa, start the argon ion source to clean the silicon window chip for 10 min. The ion source neutralization current is 0.5 A, the neutralization gas flow rate is 8 sccm, the anode voltage is 150 V, the anode current is 2 A, and the argon gas flow rate is 100%; S3. On the surface of the window pane, deposit a first germanium layer with a thickness of 32 nm, a first zinc sulfide layer with a thickness of 171 nm, a second germanium layer with a thickness of 30 nm, a second zinc sulfide layer with a thickness of 202 nm, a ytterbium fluoride layer with a thickness of 457 nm, a yttrium oxide layer with a thickness of 30 nm, and a silica layer with a thickness of 70 nm in sequence. Among them, the silica is the dehydroxylated silica optical coating material of GRINM Resources & Environment Technology Institute (Beijing) Co., Ltd., and this dehydroxylated silica optical coating material has good performance; When depositing the germanium layer, the electron beam evaporation method is adopted, and the evaporation rate of germanium is 3 Å / s. The neutralization current of the Hall ion source is 0.3 A, the neutralization gas flow rate is 8 sccm, the anode voltage is 100 V, the anode current is 1.2 A, and the argon gas flow rate is 100%. When depositing the zinc sulfide layer, the molybdenum box resistance evaporation method is adopted, and the evaporation rate of zinc sulfide is 6 Å / s. The neutralization current of the Hall ion source is 0.3 A, the neutralization gas flow rate is 8 sccm, the anode voltage is 100 V, the anode current is 1.2 A, and the argon gas flow rate is 100%. When depositing the ytterbium fluoride layer, the molybdenum box resistance evaporation method is adopted, and the evaporation rate of ytterbium fluoride is 5 Å / s. The neutralization current of the Hall ion source is 0.3 A, the neutralization gas flow rate is 8 sccm, the anode voltage is 100 V, the anode current is 1.2 A, and the argon gas flow rate is 100%. When depositing the yttrium oxide layer, the electron beam evaporation method is adopted, and the evaporation rate of yttrium oxide is 2 Å / s. The neutralization current of the Hall ion source is 0.3 A, the neutralization gas flow rate is 8 sccm, the anode voltage is 100 V, the anode current is 1.2 A, and the argon gas flow rate is 100%. When depositing the silica layer, the electron beam evaporation method is adopted, and the evaporation rate of silica is 2 Å / s. The neutralization current of the Hall ion source is 0.7 A, the neutralization gas flow rate is 8 sccm, the anode voltage is 200 V, the anode current is 3.5 A, and the argon gas flow rate is 100%. After the film layers are deposited in sequence, take out the silicon window pane, and after simple treatment, wait for coating on the other side; S4. Repeat steps 1 - 3 to deposit film layers on the other side of the silicon window pane in sequence.

[0023] Use an Agilent Cary 630 FTIR infrared spectrometer to test the transmittance of the samples prepared in Examples 1 and 3 at a wavelength of 3 - 5 μm, as Figure 1-2 shown. Its double-sided comprehensive average transmittance reaches more than 97%, meeting the transmittance requirements. On this basis, test its abrasion resistance and durability to meet the overall requirements.

[0024] Comparative Example 1: In Example 1, cancel the deposition of the silica layer in preparation method step S3, and the others are the same as in Example 1, which will not be elaborated here.

[0025] Comparative Example 2: In Example 1, replace the 50 nm yttrium oxide layer in preparation method step S3 with a 50 nm zinc sulfide layer, and the others are the same as in Example 1, which will not be elaborated here.

[0026] The following performance tests were conducted on the samples obtained from the above Examples 1-3 and Comparative Examples 1-2.

[0027] (1)Adhesion test The sample film layer surface was firmly adhered to with a MICBOND NO.405 test tape. After quickly pulling the tape vertically and peeling it off, the surface quality of the sample film layer was good, and there was no film peeling phenomenon, indicating that the connectivity of each sample after coating could meet the requirements.

[0028] (2)Salt spray test The coated silicon window samples were placed in a salt spray test chamber. After 48 hours of salt spray testing, no film peeling or surface blurring occurred in the samples, indicating that the corrosion resistance of each sample after coating could meet the requirements.

[0029] (3)High and low temperature test The coated silicon window samples were placed in a high and low temperature test chamber. After being kept at a high temperature of 85 °C and a low temperature of -65 °C for 5 hours respectively, the surface quality of the sample film layer was good, and there were no blisters, cracks, film peeling and other phenomena.

[0030] (4)Humidity and heat test The coated silicon window samples were placed in a humidity and heat test chamber (temperature 55 °C, humidity 95%). After being taken out after standing for 24 hours, the surface quality of the sample film layer was good, and there were no blisters, cracks, film peeling and other phenomena.

[0031] (5)Friction test Two layers of dry degreased gauze were wrapped outside the rubber friction head. Under a pressure of 10 N, the sample surface was rubbed along the same trajectory. After 20 round trips, the surface quality of the sample film layer prepared in Examples 1-3 was good, without scratches. However, scratches appeared on the surface of the sample film layer prepared in Comparative Example 1, and the silicon dioxide layer peeled off on the surface of the sample film layer prepared in Comparative Example 2.

[0032] (6)Abrasion resistance test Two layers of dry degreased gauze were wrapped outside the rubber friction head. Under a pressure of 2 N, the sample surface was rubbed along the same trajectory. After 3000 round trips, the surface quality of the sample film layer prepared in Examples 1-2 was good, without scratches. However, the surface of the sample film layer prepared in Comparative Examples 1-3 was blurred and serious scratches appeared.

[0033] In summary, in the present invention, a mid-wave infrared antireflection film is deposited on the surface of a silicon window. By setting yttrium oxide and silicon dioxide as a hardening film layer on the outer layer of the film system, the deposited mid-wave infrared antireflection film can achieve a double-sided comprehensive average transmittance Tave > 97%, and at the same time, the durability of the mid-wave infrared silicon window is achieved at one time.

Claims

1. A mid-wave infrared durable anti-reflection film for a silicon window, characterized in that: It includes a base layer, an intermediate layer and a wear-resistant hardened layer, wherein the intermediate layer and the wear-resistant hardened layer are arranged on both sides of the base layer, the intermediate layer is located between the base layer and the wear-resistant hardened layer, the base layer is a silicon window sheet, the intermediate layer includes a first germanium layer, a first zinc sulfide layer, a second germanium layer, a second zinc sulfide layer and an ytterbium fluoride layer in sequence, and the wear-resistant hardened layer includes an yttrium oxide layer and a silicon dioxide layer in sequence.

2. The mid-wave infrared durable anti-reflection film for silicon window according to claim 1, characterized in that: The silicon dioxide layer is a dehydroxylated silicon dioxide layer.

3. The mid-wave infrared durable anti-reflection film for silicon window according to claim 1, characterized in that: The thickness of the first germanium layer is 30-35nm, the thickness of the first zinc sulfide layer is 165-175nm, the thickness of the second germanium layer is 30-35nm, the thickness of the second zinc sulfide layer is 190-210nm, the thickness of the ytterbium fluoride layer is 420-480nm, the thickness of the yttrium oxide layer is 30-50nm, and the thickness of the silicon dioxide layer is 50-70nm.

4. A method for preparing a mid-wave infrared durable anti-reflection film for a silicon window according to any one of claims 1 to 3, comprising the following steps: S1 cleans the silicon window to be coated, places it in the coating machine chamber, starts the coating machine vacuum system, and sets the chamber baking temperature to 125-135°C; S2 After the chamber background vacuum reaches 6.0E-4Pa, start the argon ion source to clean the silicon window for 10 minutes. The ion source neutralization current is 0.5A, the neutralization gas flow rate is 8sccm, the anode voltage is 150V, the anode current is 2A, and the argon gas flow rate is 100%; S3 sequentially depositing a first germanium layer, a first zinc sulfide layer, a second germanium layer, a second zinc sulfide layer, an ytterbium fluoride layer, an yttrium oxide layer and a silicon dioxide layer on the surface of the silicon window; S4 repeats steps 1-3 to deposit film layers on the other side of the silicon window in sequence.

5. The method for preparing a mid-wave infrared durable anti-reflection film for a silicon window according to claim 4, characterized in that: The germanium layer, yttrium oxide layer and silicon dioxide layer are prepared by electron beam evaporation process.

6. The method for preparing a mid-wave infrared durable anti-reflection film for a silicon window according to claim 4, characterized in that: The zinc sulfide layer and the ytterbium fluoride layer are prepared by using a resistance heating evaporation process.

7. The method for preparing a mid-wave infrared durable anti-reflection film for a silicon window according to claim 4, characterized in that: The germanium layer, zinc sulfide layer, yttrium oxide layer and silicon dioxide layer are all formed by ion-assisted plating.

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