A composite film structure of a rubidium atomic clock with low frequency drift rate and a preparation method thereof

Abstract

The application provides a composite film structure of a low-frequency drift rate rubidium atomic clock, which is deposited on the inner wall of the rubidium atomic clock and sequentially comprises an oxide layer, a transition layer and a noble metal lattice. The material of the oxide layer is Al2O3, and the thickness is 20-30 nm; the material of the transition layer is Ti, and the thickness is 10-20 nm; and the material of the noble metal lattice is Ir, and the thickness is 5-15 nm. The application is prepared by a thermal atomic layer deposition and a plasma enhanced atomic layer deposition, can form a chemical reaction and a physical diffusion barrier layer, stabilizes the state of a working medium in an absorption bubble, effectively reduces a longitudinal diffusion process and a transverse movement process of rubidium atoms in the rubidium atomic clock, thereby effectively reduces a frequency drift rate of the rubidium atoms, reduces an output frequency change process with time, and reduces the frequency drift rate of the rubidium atomic clock.

Description

Technical Field

[0001] This invention relates to the field of vacuum coating technology, and more specifically, to a composite thin film structure of a low-frequency drift rate rubidium atomic clock and its preparation method. Background Technology

[0002] Rubidium atomic clocks are atomic frequency standards with simple structure and high stability. They have advantages such as light weight, small size, low power consumption and low cost, and are widely used in navigation, communication and other fields.

[0003] Frequency drift is an inherent characteristic of atomic clocks, representing the relative change in the output frequency of an atomic clock in one direction per unit time (e.g., one day). It describes the degree of change in the output frequency system caused by the aging effect of internal components. Although the output frequency of an atomic clock can be calibrated, frequency drift cannot be changed. Rubidium atomic clocks have a relatively large initial drift rate, making it difficult to achieve the required drift rate for products, and the time it takes for the drift to reach its final value is very long.

[0004] With continuous technological advancements, the frequency stability of the rubidium atomic frequency standard has been continuously improved, approaching the level of the active hydrogen atomic frequency standard (3.0 × 10⁻⁶). -13 / S). However, compared to the cesium and hydrogen atomic frequency standards, the rubidium atomic frequency standard has a frequency drift rate of (5.0 × 10⁻⁶). -13 The improvement (per day) was not significant, and it was similar to the hydrogen atom frequency standard (1.0 × 10⁻⁶). -15 The rubidium atomic clock still lags significantly behind the standard rubidium atomic clock (per day), which limits its application and system performance.

[0005] Therefore, the development of low-frequency drift rate rubidium atomic clocks from a physical perspective has become an urgent problem to be solved. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the purpose of this invention is to create a composite thin film structure of oxide / transition layer / noble metal lattice on the inner wall surface of a rubidium atomic clock, thereby forming a chemical reaction and physical diffusion barrier layer, stabilizing the state of the working medium in the absorption bubble, reducing the output frequency change over time, and thus reducing the frequency drift rate of the rubidium atomic clock.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] In a first aspect, the present invention provides a composite thin film structure for a low-frequency drift rate rubidium atomic clock, wherein the composite thin film structure is deposited on the inner wall of the rubidium atomic clock and comprises, in sequence, an oxide layer, a transition layer and a noble metal lattice.

[0009] Furthermore, the oxide layer is made of Al2O3 and is located near the inner wall; the transition layer is made of Ti; and the noble metal lattice is made of Ir and is located away from the inner wall.

[0010] Furthermore, the oxide layer has a thickness of 20–30 nm, the transition layer has a thickness of 10–20 nm, and the noble metal lattice has a thickness of 5–15 nm.

[0011] Furthermore, the inner wall material of the rubidium atomic clock is high borosilicate glass.

[0012] Secondly, the present invention provides a method for preparing the composite thin film structure of the low-frequency drift rate rubidium atomic clock, comprising the following steps:

[0013] Step S1: Prepare the oxide layer using thermal atomic layer deposition (TLD) technology;

[0014] Step S2: The transition layer is prepared using plasma-assisted enhanced atomic layer deposition (PAD).

[0015] Step S3: The noble metal lattice is prepared using plasma-assisted enhanced atomic layer deposition (PAD).

[0016] Furthermore, before preparing the oxide layer using thermal atomic layer deposition technology, the following steps are included:

[0017] Step S0: Place the rubidium atomic clock in the reaction chamber, evacuate to 1×10-2~1×10-3 Pa, and heat to 200~350℃.

[0018] Furthermore, the preparation of the oxide layer using thermal atomic layer deposition technology includes:

[0019] Step S11: The reaction precursor trimethylaluminum (Al(CH3)3) is transported through the reaction chamber in the form of a gas pulse by nitrogen gas, and a monoadsorbed layer of precursor molecules is formed by chemical adsorption. The precursor flow rate is 70-200 sccm, the introduction time is 0.1s-0.6s, and the nitrogen flow rate is 150-250 sccm.

[0020] Step S12: Introduce nitrogen into the reaction chamber to remove unadsorbed reaction precursors. The nitrogen flow rate is 150-250 sccm and the introduce time is 5-20 s.

[0021] Step S13: Introduce a reaction gas into the reaction chamber to react with the adsorbed reaction precursor on the surface to generate the oxide layer. The reaction gas flow rate is 50-250 sccm and the introduction time is 5-15 s. The reaction gas is preferably deionized water molecules or O3.

[0022] Step S14: Introduce nitrogen gas into the reaction chamber at a rate of 150–250 sccm for 5–20 seconds to remove excess reaction gases and byproducts.

[0023] Furthermore, performing the thermal atomic layer deposition steps S11 to S14 once constitutes one deposition cycle, and the obtained oxide layer is the thickness of a single oxide molecule. Repeating steps S11 to S14 N times yields an oxide layer with a thickness of N single oxide molecules.

[0024] Furthermore, the preparation of the transition layer using plasma-assisted enhanced atomic layer deposition technology includes:

[0025] Step S21: The precursor tetra(dimethylamine)titanium (TDMAT) is passed through the reaction chamber in the form of a gas pulse by nitrogen transport, and a monoadsorbed layer of precursor molecules is formed by chemical adsorption. The precursor flow rate is 70-200 sccm, the passage time is 0.1s-0.6s, and the nitrogen flow rate is 150-250 sccm.

[0026] Step S22: Introduce nitrogen into the reaction chamber to remove unadsorbed reaction precursors. The nitrogen flow rate is 150-250 sccm and the introduce time is 5-20 s.

[0027] Step S23: Introduce a reaction gas into the reaction chamber to conduct a surface chemical reaction on the oxide layer and generate the transition layer. The reaction gas flow rate is 50-250 sccm and the introduction time is 5-15s. The reaction gas is preferably O2 or a N2 / H2 / Ar mixture.

[0028] Step S24: Introduce nitrogen gas into the reaction chamber at a rate of 150–250 sccm for 5–20 seconds to remove excess reaction gases and byproducts.

[0029] Furthermore, performing the plasma-assisted enhanced atomic layer deposition steps S21 to S24 once constitutes one deposition cycle, and the obtained metal transition layer is a single metal atom layer thickness. Steps S21 to S24 are repeated M times to obtain a metal transition layer with M single metal atom layer thicknesses.

[0030] Furthermore, the fabrication of the noble metal lattice using plasma-assisted enhanced atomic layer deposition (PAD) technology includes:

[0031] Step S31: The reaction precursor iridium triacetylacetone (Ir(acac)3) is passed through the reaction chamber in the form of a gas pulse by nitrogen transport, and a monoadsorption layer of precursor molecules is formed by chemical adsorption. The precursor flow rate is 70-200 sccm, the passage time is 0.1s-0.6s, and the nitrogen flow rate is 150-250 sccm.

[0032] Step S32: Introduce nitrogen into the reaction chamber to remove unadsorbed reaction precursors. The nitrogen flow rate is 150-250 sccm and the introduce time is 5-20 s.

[0033] Step S33: Introduce a reaction gas into the reaction chamber to conduct a surface chemical reaction on the transition layer and generate the noble metal lattice. The reaction gas flow rate is 50-250 sccm and the introduction time is 5-15 s. O2 is the preferred reaction gas.

[0034] Step S34: Nitrogen gas is introduced into the reaction chamber at a flow rate of 150–250 sccm for 5–20 seconds to remove excess reaction gases and byproducts, thereby obtaining the composite thin film structure.

[0035] Further, performing the plasma-assisted enhanced atomic layer deposition steps S31 to S34 once constitutes one deposition cycle, and the obtained noble metal lattice has a single noble metal atomic layer thickness; repeating steps S31 to S34 K times yields the noble metal lattice with K single metal atomic layer thicknesses.

[0036] Furthermore, the thickness of a single oxide molecule is approximately 0.100 nm, and the Nth iteration is 200 to 300 times; the thickness of a single metal atom layer is 0.145 nm, and the Mth iteration is 69 to 138 times; the thickness of a single noble metal atom layer is 0.135 nm, and the Kth iteration is 37 to 112 times.

[0037] The technical solution of this invention has the following beneficial effects:

[0038] This invention involves preparing an oxide / transition layer / noble metal lattice composite film on the inner surface of a rubidium atomic clock. The oxide film acts as a barrier layer against chemical reactions and physical diffusion, stabilizing the state of the working medium within the clock. The noble metal lattice adsorbs rubidium atoms, restricting their movement. The transition layer enhances the adhesion between the noble metal and the substrate material, preventing the noble metal lattice from detaching during the use of the rubidium atomic clock. This oxide / transition layer / noble metal lattice composite film effectively reduces the longitudinal diffusion and lateral movement of rubidium atoms in the rubidium atomic clock, decreasing the frequency change over time and thus effectively reducing the frequency drift rate of rubidium atoms. Attached Figure Description

[0039] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0040] Figure 1 This is a schematic diagram of the composite thin film structure of the low-frequency drift rate rubidium atomic clock provided in an embodiment of the present invention;

[0041] In the picture:

[0042] 1- High borosilicate glass substrate (inner wall of rubidium atomic clock);

[0043] 2-Oxide layer;

[0044] 3-Transition layer;

[0045] 4-Precious metal dot matrix. Detailed Implementation

[0046] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0047] Where specific experimental steps or conditions are not specified in the embodiments, they can be performed according to the conventional experimental steps or conditions described in the literature in this field. All raw materials or instruments used are commercially available conventional products, including but not limited to the raw materials or instruments used in the embodiments of this invention.

[0048] It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments of the present invention can be combined with each other. The following will be discussed in conjunction with the appendix. Figure 1 This paper provides a detailed description of a composite thin film structure for a low-frequency drift rate rubidium atomic clock and its preparation method, as provided in the embodiments of the present invention.

[0049] The technical problem this invention aims to solve is to overcome the fact that existing methods do not significantly improve the frequency drift rate of rubidium atomic clocks, failing to meet the requirements of practical applications. To address this, a composite thin film structure for a low-frequency drift rate rubidium atomic clock and its preparation method are proposed. The basic principle is to prepare an oxide / transition layer / noble metal lattice composite thin film on the inner wall surface of the rubidium atomic clock. The oxide film acts as a barrier layer for chemical reactions and physical diffusion, stabilizing the state of the working medium within the clock. The noble metal lattice adsorbs rubidium atoms, restricting their movement. The transition layer enhances the bonding force between the noble metal and the substrate material, preventing the noble metal lattice from detaching during the use of the rubidium atomic clock. The oxide / transition layer / noble metal lattice composite thin film of this invention can effectively reduce the longitudinal diffusion and lateral movement of rubidium atoms in the rubidium atomic clock, reducing the change in output frequency over time, thereby effectively reducing the frequency drift rate of rubidium atoms.

[0050] Example

[0051] Please see Figure 1 This is a schematic diagram of a composite thin-film structure for a low-frequency drift rate rubidium atomic clock, provided by an embodiment of the present invention. Figure 1 As shown in the embodiment of the present invention, the composite thin film structure of the low frequency drift rate rubidium atomic clock is deposited on the inner wall of the rubidium atomic clock (the inner wall material is a high borosilicate glass substrate 1), and from bottom to top includes an oxide layer 2, a transition layer 3 and a noble metal lattice 4.

[0052] Specifically, in this embodiment of the invention, the oxide layer 2 is made of Al2O3 and has a thickness of 20-30 nm, close to the borosilicate glass substrate 1; the transition layer 3 is made of Ti and has a thickness of 10-20 nm; the noble metal lattice 4 is made of Ir and has a thickness of 5-15 nm, and is located near the borosilicate glass substrate 1.

[0053] Specifically, in this embodiment of the invention, the method for preparing the composite thin film structure includes the following steps:

[0054] Step S1: The oxide layer 2 is prepared on the surface of the borosilicate glass substrate 1 using thermal atomic layer deposition technology;

[0055] Step S2: The transition layer 3 is prepared on the surface of the oxide layer 2 using plasma-assisted enhanced atomic layer deposition (PAD).

[0056] Step S3: The precious metal lattice 4 is prepared on the surface of the transition layer 3 using plasma-assisted enhanced atomic layer deposition (PAD).

[0057] Specifically, in this embodiment of the invention, before preparing the oxide layer using thermal atomic layer deposition technology, the following steps are included:

[0058] Step S0: Place the rubidium atomic clock in the reaction chamber and evacuate to a vacuum of 1×10⁻⁶. -2 ~1×10 -3 Pa, heated to 200-350℃.

[0059] Specifically, in this embodiment of the invention, the preparation of the oxide layer using thermal atomic layer deposition technology includes:

[0060] Step S11: The reaction precursor trimethylaluminum (Al(CH3)3) is transported through the reaction chamber in the form of a gas pulse by nitrogen gas, and a monoadsorbed layer of precursor molecules is formed by chemical adsorption. The precursor flow rate is 70-200 sccm, the introduction time is 0.1s-0.6s, and the nitrogen flow rate is 150-250 sccm.

[0061] Step S12: Introduce nitrogen into the reaction chamber to remove unadsorbed reaction precursors. The nitrogen flow rate is 150-250 sccm and the introduce time is 5-20 s.

[0062] Step S13: Introduce a reaction gas into the reaction chamber to react with the adsorbed reaction precursor on the surface to generate the oxide layer. The reaction gas flow rate is 50-250 sccm and the introduction time is 5-15 s. The reaction gas is preferably deionized water molecules or O3.

[0063] Step S14: Introduce nitrogen gas into the reaction chamber at a rate of 150–250 sccm for 5–20 seconds to remove excess reaction gases and byproducts.

[0064] Specifically, in this embodiment of the invention, performing the thermal atomic layer deposition steps S11 to S14 once constitutes one deposition cycle, and the obtained oxide layer is the thickness of a single oxide molecule. Repeating steps S11 to S14 N times yields an oxide layer with the thickness of N single oxide molecules.

[0065] Specifically, in this embodiment of the invention, the preparation of the transition layer using plasma-assisted enhanced atomic layer deposition technology includes:

[0066] Step S21: The precursor tetra(dimethylamine)titanium (TDMAT) is passed through the reaction chamber in the form of a gas pulse by nitrogen transport, and a monoadsorbed layer of precursor molecules is formed by chemical adsorption. The precursor flow rate is 70-200 sccm, the passage time is 0.1s-0.6s, and the nitrogen flow rate is 150-250 sccm.

[0067] Step S22: Introduce nitrogen into the reaction chamber to remove unadsorbed reaction precursors. The nitrogen flow rate is 150-250 sccm and the introduce time is 5-20 s.

[0068] Step S23: Introduce a reaction gas into the reaction chamber to conduct a surface chemical reaction on the oxide layer and generate the transition layer. The reaction gas flow rate is 50-250 sccm and the introduction time is 5-15s. The reaction gas is preferably O2 or a N2 / H2 / Ar mixture.

[0069] Step S24: Introduce nitrogen gas into the reaction chamber at a rate of 150–250 sccm for 5–20 seconds to remove excess reaction gases and byproducts.

[0070] Specifically, in this embodiment of the invention, performing the plasma-assisted enhanced atomic layer deposition steps S21 to S24 once constitutes one deposition cycle, and the obtained metal transition layer is a single metal atom layer thickness. Steps S21 to S24 are repeated M times to obtain a metal transition layer with a thickness of M single metal atoms.

[0071] Specifically, in this embodiment of the invention, the fabrication of the noble metal lattice using plasma-assisted enhanced atomic layer deposition (PAD) technology includes:

[0072] Step S31: The reaction precursor iridium triacetylacetone (Ir(acac)3) is passed through the reaction chamber in the form of a gas pulse by nitrogen transport, and a monoadsorption layer of precursor molecules is formed by chemical adsorption. The precursor flow rate is 70-200 sccm, the passage time is 0.1s-0.6s, and the nitrogen flow rate is 150-250 sccm.

[0073] Step S32: Introduce nitrogen into the reaction chamber to remove unadsorbed reaction precursors. The nitrogen flow rate is 150-250 sccm and the introduce time is 5-20 s.

[0074] Step S33: Introduce a reaction gas into the reaction chamber to conduct a surface chemical reaction on the transition layer and generate the noble metal lattice. The reaction gas flow rate is 50-250 sccm and the introduction time is 5-15 s. O2 is the preferred reaction gas.

[0075] Step S34: Nitrogen gas is introduced into the reaction chamber at a flow rate of 150-250 sccm for 5-20 seconds to remove excess reaction gases and reaction byproducts, thereby obtaining the composite thin film structure.

[0076] Specifically, in this embodiment of the invention, performing the plasma-assisted enhanced atomic layer deposition steps S31 to S34 once constitutes one deposition cycle, and the obtained noble metal lattice has a single noble metal atomic layer thickness; repeating steps S31 to S34 K times yields the noble metal lattice with K single metal atomic layer thicknesses.

[0077] Specifically, in this embodiment of the invention, the thickness of a single oxide molecule is approximately 0.100 nm, and the Nth iteration is 200 to 300 times; the thickness of a single metal atom layer is 0.145 nm, and the Mth iteration is 69 to 138 times; the thickness of a single noble metal atom layer is 0.135 nm, and the Kth iteration is 37 to 112 times.

[0078] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A composite thin-film structure for a low-frequency drift-rate rubidium atomic clock, characterized in that, The composite thin film structure is deposited on the inner wall of the rubidium atomic clock and sequentially includes an oxide layer, a transition layer, and a noble metal lattice. The oxide layer is made of Al2O3 and is located near the inner wall; The material of the transition layer is Ti; The material of the precious metal lattice is Ir, and it is located away from the inner wall.

2. The composite thin-film structure of the low-frequency drift-rate rubidium atomic clock according to claim 1, characterized in that, The oxide layer has a thickness of 20-30 nm; the transition layer has a thickness of 10-20 nm; and the noble metal lattice has a thickness of 5-15 nm.

3. The composite thin-film structure of the low-frequency drift-rate rubidium atomic clock according to claim 1, characterized in that, The inner wall material of the rubidium atomic clock is high borosilicate glass.

4. A method for preparing a composite thin film structure of a low-frequency drift rate rubidium atomic clock according to any one of claims 1 to 3, characterized in that, Includes the following steps: Step S1: Prepare the oxide layer using thermal atomic layer deposition (TLD) technology; Step S2: The transition layer is prepared using plasma-assisted enhanced atomic layer deposition (PAD). Step S3: The noble metal lattice is prepared using plasma-assisted enhanced atomic layer deposition (PAD).

5. The method for preparing the composite thin film structure of the low-frequency drift rate rubidium atomic clock according to any one of claims 1 to 3 as described in claim 4, characterized in that, Before preparing the oxide layer using thermal atomic layer deposition technology, the following steps are included: Step S0: Place the rubidium atomic clock in the reaction chamber and evacuate to a vacuum of 1×10⁻⁶. -2 ~1×10 -3 Pa, heated to 200~350 ℃.

6. The method for preparing the composite thin film structure of the low-frequency drift rate rubidium atomic clock according to any one of claims 1 to 3 as described in claim 4, characterized in that, The preparation of the oxide layer using thermal atomic layer deposition technology includes: Step S11: The reaction precursor trimethylaluminum (Al(CH3)3) is passed through the reaction chamber in the form of a gas pulse via nitrogen transport, forming a monoadsorbed layer of precursor molecules by chemical adsorption. The precursor flow rate is 70~200 sccm, the passage time is 0.1 s~0.6 s, and the nitrogen flow rate is 150~250 sccm. Step S12: Introduce nitrogen into the reaction chamber to remove unadsorbed reaction precursors. The nitrogen flow rate is 150~250 sccm and the introduce time is 5~20 s. Step S13: Introduce a reaction gas into the reaction chamber to react with the adsorbed reaction precursor on the surface to generate the oxide layer. The reaction gas flow rate is 50~250 sccm and the introduction time is 5~15 s. The reaction gas is deionized water. Step S14: Introduce nitrogen gas into the reaction chamber at a rate of 150-250 sccm for 5-20 s to remove excess reaction gases and byproducts.

7. The method for preparing the composite thin film structure of the low-frequency drift rate rubidium atomic clock according to any one of claims 1 to 3 as described in claim 6, characterized in that, One thermal atomic layer deposition step S11 to S14 is one deposition cycle, and the obtained oxide layer is the thickness of a single oxide molecule. Steps S11 to S14 are repeated N times to obtain an oxide layer with a thickness of N single oxide molecules.

8. The method for preparing the composite thin film structure of the low-frequency drift rate rubidium atomic clock according to any one of claims 1 to 3 as described in claim 7, characterized in that, The term N is 200 to 300 times.

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