Atomic gas chamber and method for manufacturing the same

Abstract

The present invention discloses a method for manufacturing an atomic gas chamber, the method comprising: forming a first bonding layer having a first through hole on a first sapphire substrate, and forming a second bonding layer having a second through hole on a second sapphire substrate, the first through hole and the second through hole corresponding to each other; placing a filling material in the first through hole or the second through hole; bonding the first bonding layer and the second bonding layer. The present invention also discloses an atomic gas chamber manufactured by the above manufacturing method. The present invention solves the problem of consumption reaction between the material of the atomic gas chamber and the alkali metal and high leakage of buffer gas, which leads to a reduction in the service life of the atomic gas chamber.

Description

Technical Field

[0001] The invention relates to the field of semiconductor micro-electromechanical systems, and in particular to an atomic gas chamber and a manufacturing method thereof. Background Art

[0002] The atomic gas chamber is a sensitive instrument for realizing quantum state regulation and monitoring among many quantum sensor devices. It stores atomic vapor in a light-transmitting container to form a closed system. In this system, according to the needs of different fields, the quantum state of atomic vapor is precisely regulated and monitored using optical, electrical, material science and other technical means to achieve high-precision measurement of physical quantities.

[0003] Traditionally, MEMS chips use silicon as the cavity and borosilicate glass as the optical window to seal alkali metal elements and buffer gases in the atomic gas chamber. However, the alkali metal elements are gradually consumed by physical diffusion or chemical reaction with the cavity wall. In particular, this consumption reaction increases rapidly as the use temperature increases. According to our previous experimental results, the sealed alkali metal is basically completely consumed after baking at 300 degrees Celsius for one hour. Therefore, reducing or avoiding the consumption of alkali metal elements in the atomic gas chamber has become the key to the preparation and control of atomic gas chambers for high-performance MEMS chips. The main reasons for the shortening of the life of the atomic gas chamber are: 1. The amount of alkali metal sealed in each gas chamber is limited. If the amount is too small or disappears, the device will fail. 2. The alkali metal elements will diffuse into the silicon body or react with the free oxygen inside the silicon and glass. This consumption reaction accelerates with increasing temperature. 3. A buffer gas (such as N2: Ar or Ne, He) of a certain pressure is sealed in the atomic chamber at the same time. The pressure must be kept constant, but the buffer gas, especially the inert gas Ar, Ne, He, etc., will penetrate silicon and glass, causing the gas pressure to change (either internal or external infiltration is possible), resulting in failure of the chip gas chamber. Summary of the invention

[0004] In order to achieve the above-mentioned purpose, the present invention provides the following technical solutions:

[0005] In one aspect of the present invention, a method for manufacturing an atomic gas chamber is provided, the method comprising:

[0006] Forming a first bonding layer having a first through hole on the first sapphire substrate, and forming a second bonding layer having a second through hole on the second sapphire substrate, wherein the first through hole and the second through hole correspond to each other one by one;

[0007] placing a filling material in the first through hole or the second through hole;

[0008] The first bonding layer and the second bonding layer are bonded.

[0009] Preferably, the first bonding layer and the second bonding layer are made of copper.

[0010] Preferably, the step of forming a first bonding layer having a first through hole on the first sapphire substrate and forming a second bonding layer having a second through hole on the second sapphire substrate comprises:

[0011] forming a first seed metal layer on the first sapphire substrate by a sputtering process, and forming a second seed metal layer on the second sapphire substrate by a sputtering process;

[0012] forming a first sacrificial layer having a hollow pattern on the first seed metal layer, and forming a second sacrificial layer having a hollow pattern on the second seed metal layer; the hollow pattern of the first sacrificial layer is the same as the hollow pattern of the second sacrificial layer;

[0013] forming a first metal layer in the hollow pattern of the first sacrificial layer by using an electroplating process, and forming a second metal layer in the hollow pattern of the second sacrificial layer by using an electroplating process;

[0014] The first sacrificial layer and the second sacrificial layer are stripped and removed to expose a portion of the first seed metal layer and a portion of the second seed metal layer;

[0015] The exposed first seed metal layer and the second seed metal layer are removed.

[0016] Preferably, the thickness of the first metal layer is less than or equal to the thickness of the first sacrificial layer, and the thickness of the second metal layer is less than or equal to the thickness of the second sacrificial layer.

[0017] Preferably, before stripping and removing the first sacrificial layer and the second sacrificial layer, the manufacturing method further includes: performing chemical mechanical polishing and planarizing treatment on the surfaces of the first metal layer and the first sacrificial layer, and performing chemical mechanical polishing and planarizing treatment on the surfaces of the second metal layer and the second sacrificial layer.

[0018] Preferably, the manufacturing method further comprises:

[0019] forming a first adhesion layer between the first sapphire substrate and the first bonding layer, and forming a second adhesion layer between the second sapphire substrate and the second bonding layer;

[0020] The first through hole penetrates the first adhesive layer, and the second through hole penetrates the second adhesive layer.

[0021] Preferably, forming a first bonding layer having a first through hole on the first sapphire substrate, and forming a second bonding layer having a second through hole on the second sapphire substrate comprises:

[0022] forming a first adhesion layer on the first sapphire substrate, and forming a second adhesion layer on the second sapphire substrate;

[0023] forming a first seed metal layer on the first adhesion layer, and forming a second seed metal layer on the second adhesion layer;

[0024] forming a first sacrificial layer having a hollow pattern on the first seed metal layer, and forming a second sacrificial layer having a hollow pattern on the second seed metal layer; the hollow pattern of the first sacrificial layer is the same as the hollow pattern of the second sacrificial layer;

[0025] forming a first metal layer in the hollow pattern of the first sacrificial layer by using an electroplating process, and forming a second metal layer in the hollow pattern of the second sacrificial layer by using an electroplating process;

[0026] The first sacrificial layer and the second sacrificial layer are stripped and removed to expose a portion of the first seed metal layer and a portion of the second seed metal layer;

[0027] The exposed portion of the first seed metal layer and the first adhesion layer directly under the portion of the first seed metal layer are removed, and the exposed portion of the second seed metal layer and the second adhesion layer directly under the portion of the second seed metal layer are removed.

[0028] Preferably, the thickness of the first metal layer is smaller than the thickness of the first sacrificial layer, and the thickness of the second metal layer is smaller than the thickness of the second sacrificial layer.

[0029] Preferably, before stripping and removing the first sacrificial layer and the second sacrificial layer, the manufacturing method further includes: performing chemical mechanical polishing and planarizing treatment on the surfaces of the first metal layer and the first sacrificial layer, and performing chemical mechanical polishing and planarizing treatment on the surfaces of the second metal layer and the second sacrificial layer.

[0030] Another aspect of the present invention provides an atomic gas chamber manufactured by the above manufacturing method.

[0031] Compared with the prior art, the method for manufacturing the atomic gas chamber provided by the present invention adopts a method of forming copper bonding layers on two sapphire substrates respectively, and using the copper bonding layers to form a metal sealing ring, thereby forming a sealing structure of the atomic gas chamber, thereby avoiding the chemical reaction between the material constituting the atomic gas chamber and the alkali metal, thereby improving the reliability and stability of the atomic gas chamber and increasing the service life of the atomic gas chamber. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figures 1 to 8 FIG. 4 is a process flow chart of a method for manufacturing an atomic gas chamber according to an embodiment of the present invention. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical scheme and advantages of the present invention clearer, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. Examples of these preferred embodiments are illustrated in the accompanying drawings. The embodiments of the present invention shown in the accompanying drawings and described according to the accompanying drawings are merely exemplary, and the present invention is not limited to these embodiments.

[0034] It should also be noted that, in order to avoid obscuring the present invention due to unnecessary details, only structures and / or processing steps closely related to the solutions according to the present invention are shown in the accompanying drawings, while other details that are not closely related to the present invention are omitted.

[0035] In order to solve the shortcomings of the prior art, the inventors have found through research that aluminum oxide (Al2O3) film can block the diffusion and penetration of alkali metal atomic gas. Based on this fact, the present invention provides a method for forming an atomic gas chamber using a sapphire (mainly composed of Al2O3) substrate. The technical solution of the present invention is further described below in conjunction with specific embodiments.

[0036] Example 1

[0037] The method for manufacturing the atomic gas chamber provided in this embodiment includes:

[0038] Step 1: Form a first bonding layer 1c having a first through hole A on a first sapphire substrate 1a, and form a second bonding layer 1d having a second through hole A' on a second sapphire substrate 1b, wherein the first through hole A and the second through hole A' correspond one to one, wherein at least one pair of the first through hole A and the second through hole A' is formed. It should be noted that the one-to-one correspondence between the first through hole A and the second through hole A' means that the projection area formed by the first through hole A on the second bonding layer 1d overlaps with the second through hole A' (e.g. Figure 7 or the projection area formed by the second through hole A' on the first bonding layer 1c overlaps with the first through hole A. The shape of the first through hole A is the same as the shape of the second through hole A', and they are centrally symmetrical to each other.

[0039] Step 2: Place a filling material 5 (such as Figure 7 As shown), the filling material 5 is alkali metal atomic gas, and the filling method can adopt existing technical means, so it will not be described in detail.

[0040] Step 3: Place the first bonding layer 1c and the second bonding layer 1d under a vacuum degree lower than 1×10 -6 mTorr, bonding temperature 200℃~450℃, bonding pressure 3000N~25000N (such as Figure 8 As shown), in order to prevent the bonding layer from reacting and being consumed by the atomic gas of the alkali metal, the first bonding layer 1c and the second bonding layer 1d are made of copper.

[0041] Specifically, combined Figures 1 to 6 As shown, in the above step 1, the steps of forming the first bonding layer 1c and the second bonding layer 1d include:

[0042] Step 1a: Figure 1 As shown, the surfaces of the first sapphire substrate 1a and the second sapphire substrate 1b are treated with oxygen plasma for 2 to 5 minutes, a first seed metal layer 2a is formed on the first sapphire substrate 1a by a sputtering process, and a second seed metal layer 2b is formed on the second sapphire substrate 1b by a sputtering process.

[0043] Step 1b: Figure 2 As shown, a first sacrificial layer 3a having a hollow pattern is formed on the first seed metal layer 2a, and a second sacrificial layer 3b having a hollow pattern is formed on the second seed metal layer 2b; the hollow pattern of the first sacrificial layer 3a is the same as the hollow pattern of the second sacrificial layer 3b, wherein the first sacrificial layer 3a and the second sacrificial layer 3b are photoresists with a thickness of 10um to 300um.

[0044] Step 1c, such as Figure 3 and 4 As shown, a first metal layer 4a is formed in the hollow pattern of the first sacrificial layer 3a by using an electroplating process, and a second metal layer 4b is formed in the hollow pattern of the second sacrificial layer 3b by using an electroplating process, wherein, when the first bonding layer 1c or the second bonding layer 1d has a plurality of the first through holes A or the second through holes A', in order to prevent the over-grown two adjacent first metal layers 4a or two adjacent second metal layers 4b from being connected to each other, resulting in the first through hole A and the second through hole A' being unable to connect after bonding, the thickness of the first metal layer 4a should be less than the thickness of the first sacrificial layer 3a, and the thickness of the second metal layer 4b should be less than the thickness of the second sacrificial layer 3b.

[0045] Step 1d: Figure 5 As shown, the first sacrificial layer 3a and the second sacrificial layer 3b are stripped and removed to expose a portion of the first seed metal layer 2a and a portion of the second seed metal layer 2b.

[0046] Step 1e: Figure 6As shown, the exposed portion of the first seed metal layer 2a is removed to partially expose the first sapphire substrate 1a, wherein the hollowed-out portions of the first seed metal layer 2a and the first metal layer 4a together form the first through hole A, and the remaining first seed metal layer 2a and the first metal layer 4a together form the first bonding layer 1c; at the same time, the exposed portion of the second seed metal layer 2b is removed to partially expose the second sapphire substrate 1b, wherein the hollowed-out portions of the second seed metal layer 2b and the second metal layer 4b together form the second through hole A', and the remaining second seed metal layer 2b and the second metal layer 4b together form the second bonding layer 1d.

[0047] Specifically, before the first sacrificial layer 3a and the second sacrificial layer 3b are peeled off and removed, in order to make the bonding process more convenient, the surfaces of the first metal layer 4a and the first sacrificial layer 3a are flattened. Due to the insufficient thickness uniformity and large surface roughness of the electroplated copper, it is not conducive to the implementation of airtight bonding. The flattening treatment can greatly improve the thickness uniformity and reduce the surface roughness to the order of several nanometers, thereby improving the thickness uniformity and surface roughness of the micro-electroforming copper, improving the alignment accuracy and bonding airtightness, and the surfaces of the second metal layer 4b and the second sacrificial layer 3b are also flattened. The flattening treatment can be carried out by chemical mechanical polishing (CMP: Chemical Mechanical Polishing) process.

[0048] The method for manufacturing the atomic gas chamber provided in this embodiment adopts a method of forming copper bonding layers on two sapphire substrates respectively, and using the copper bonding layers to form a metal sealing ring, thereby forming a sealing structure of the atomic gas chamber, thereby avoiding chemical reactions between the materials constituting the atomic gas chamber and the alkali metal, thereby improving the reliability and stability of the atomic gas chamber and increasing the service life of the atomic gas chamber.

[0049] Example 2

[0050] This embodiment is based on the embodiment 1, and is different from the embodiment 1 in that, in order to improve the firmness between the sapphire substrate and the bonding layer, in this embodiment, a first adhesive layer (not shown in the figure) is further formed between the first sapphire substrate 1a and the first bonding layer 1c; a second adhesive layer (not shown in the figure) is further formed between the second sapphire substrate 1b and the second bonding layer 1d. The first through hole A penetrates the first adhesive layer to expose a portion of the first sapphire substrate 1a, and the second through hole A' penetrates the second adhesive layer to expose a portion of the second sapphire substrate 1b.

[0051] Specifically, in step 1 of this embodiment, the steps of forming a first bonding layer 1c having a first through hole A on the first sapphire substrate 1a, and forming a second bonding layer 1d having a second through hole A' on the second sapphire substrate 1b include:

[0052] Step 1a′: forming a first adhesion layer on the first sapphire substrate 1a by using a magnetron sputtering process, and forming a second adhesion layer on the second sapphire substrate 1b.

[0053] Step 1b′: forming a first seed metal layer 2a on the first adhesion layer and forming a second seed metal layer 2b on the second adhesion layer by using a sputtering process.

[0054] Step 1c', forming a first sacrificial layer 3a having a hollow pattern on the first seed metal layer 2a, and forming a second sacrificial layer 3b having a hollow pattern on the second seed metal layer 2b; the hollow pattern of the first sacrificial layer 3a is the same as the hollow pattern of the second sacrificial layer 3b, wherein the first sacrificial layer 3a and the second sacrificial layer 3b are photoresists with a thickness of 10um to 300um.

[0055] Step 1d', using an electroplating process to form a first metal layer 4a in the hollow pattern of the first sacrificial layer 3a, and using an electroplating process to form a second metal layer 4b in the hollow pattern of the second sacrificial layer 3b, wherein, when the first bonding layer 1c or the second bonding layer 1d has multiple first through holes A or second through holes A', in order to prevent the excessive growth of two adjacent first metal layers 4a or two adjacent second metal layers 4b from being connected to each other, resulting in the first through hole A and the second through hole A' being unable to connect after bonding, the thickness of the first metal layer 4a should be less than the thickness of the first sacrificial layer 3a, and the thickness of the second metal layer 4b should be less than the thickness of the second sacrificial layer 3b.

[0056] Step 1e′: stripping and removing the first sacrificial layer 3a and the second sacrificial layer 3b to expose a portion of the first seed metal layer 2a and a portion of the second seed metal layer 2b.

[0057] Step 1f', remove the exposed portion of the first seed metal layer 2a and the first adhesion layer directly below the portion of the first seed metal layer 2a, so that the first sapphire substrate 1a is partially exposed, wherein the first seed metal layer 2a, the first metal layer 4a and the hollow portion of the first adhesion layer together form the first through hole A, and the remaining first seed metal layer 2a and the first metal layer 4a together form the first bonding layer 1c; at the same time, remove the exposed portion of the second seed metal layer 2b and the second adhesion layer directly below the portion of the second seed metal layer 2b, so that the second sapphire substrate 1b is partially exposed, wherein the second seed metal layer 2b, the second metal layer 4b and the hollow portion of the second adhesion layer together form the second through hole A', and the remaining second seed metal layer 2b and the second metal layer 4b together form the second bonding layer 1d.

[0058] Example 3

[0059] This embodiment provides an atomic gas chamber, which is prepared by the atomic gas chamber manufacturing method provided in the above-mentioned embodiment 1 or embodiment 2.

[0060] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0061] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for manufacturing an atomic gas chamber, characterized in that: The production method comprises: A first bonding layer (1c) having a first through hole (A) is formed on a first sapphire substrate (1a), and a second bonding layer (1d) having a second through hole (A') is formed on a second sapphire substrate (1b), wherein the first through hole (A) and the second through hole (A') correspond to each other one by one, the first bonding layer (1c) is in direct contact with the first sapphire substrate (1a), and the second bonding layer (1d) is in direct contact with the second sapphire substrate (1b); Placing a filling material (5) in the first through hole (A) or the second through hole (A'); Bonding the first bonding layer (1c) and the second bonding layer (1d); the first bonding layer (1c) and the second bonding layer (1d) are made of copper; The step of bonding the first bonding layer (1c) and the second bonding layer (1d) specifically comprises: bonding the first bonding layer (1c) and the second bonding layer (1d) at a vacuum degree of less than 1×10 -6 The bonding is performed at a bonding pressure of 3000N~25000N under an environment of 1000mTorr and a bonding temperature of 200℃~450℃.

2. The method according to claim 1, characterized in that: The steps of forming a first bonding layer (1c) having a first through hole (A) on a first sapphire substrate (1a), and forming a second bonding layer (1d) having a second through hole (A') on a second sapphire substrate (1b) include: forming a first seed metal layer (2a) on the first sapphire substrate (1a) by using a sputtering process, and forming a second seed metal layer (2b) on the second sapphire substrate (1b) by using a sputtering process; forming a first sacrificial layer (3a) having a hollow pattern on the first seed metal layer (2a), and forming a second sacrificial layer (3b) having a hollow pattern on the second seed metal layer (2b); the hollow pattern of the first sacrificial layer (3a) and the hollow pattern of the second sacrificial layer (3b) are the same; forming a first metal layer (4a) in the hollow pattern of the first sacrificial layer (3a) by using an electroplating process, and forming a second metal layer (4b) in the hollow pattern of the second sacrificial layer (3b) by using an electroplating process; The first sacrificial layer (3a) and the second sacrificial layer (3b) are peeled off and removed to expose a portion of the first seed metal layer (2a) and a portion of the second seed metal layer (2b); The exposed first seed metal layer (2a) and the second seed metal layer (2b) are removed.

3. The method according to claim 2, characterized in that: The thickness of the first metal layer (4a) is less than or equal to the thickness of the first sacrificial layer (3a), and the thickness of the second metal layer (4b) is less than or equal to the thickness of the second sacrificial layer (3b).

4. The method according to claim 3, characterized in that: Before the first sacrificial layer (3a) and the second sacrificial layer (3b) are peeled off and removed, the manufacturing method further comprises: performing a planarization treatment on the surfaces of the first metal layer (4a) and the first sacrificial layer (3a), and performing a planarization treatment on the surfaces of the second metal layer (4b) and the second sacrificial layer (3b).

5. The method according to claim 1, characterized in that: The production method further comprises: forming a first adhesion layer between the first sapphire substrate (1a) and the first bonding layer (1c), and forming a second adhesion layer between the second sapphire substrate (1b) and the second bonding layer (1d); The first through hole (A) penetrates the first adhesive layer, and the second through hole (A') penetrates the second adhesive layer.

6. The method according to claim 5, characterized in that: Forming a first bonding layer (1c) having a first through hole (A) on a first sapphire substrate (1a), and forming a second bonding layer (1d) having a second through hole (A') on a second sapphire substrate (1b) comprises: forming a first adhesion layer on the first sapphire substrate (1a), and forming a second adhesion layer on the second sapphire substrate (1b); forming a first seed metal layer (2a) on the first adhesion layer, and forming a second seed metal layer (2b) on the second adhesion layer; forming a first sacrificial layer (3a) having a hollow pattern on the first seed metal layer (2a), and forming a second sacrificial layer (3b) having a hollow pattern on the second seed metal layer (2b); the hollow pattern of the first sacrificial layer (3a) and the hollow pattern of the second sacrificial layer (3b) are the same; forming a first metal layer (4a) in the hollow pattern of the first sacrificial layer (3a) by using an electroplating process, and forming a second metal layer (4b) in the hollow pattern of the second sacrificial layer (3b) by using an electroplating process; The first sacrificial layer (3a) and the second sacrificial layer (3b) are peeled off and removed to expose a portion of the first seed metal layer (2a) and a portion of the second seed metal layer (2b); The exposed portion of the first seed metal layer (2a) and the first adhesion layer directly below the portion of the first seed metal layer (2a) are removed, and the exposed portion of the second seed metal layer (2b) and the second adhesion layer directly below the portion of the second seed metal layer (2b) are removed.

7. The manufacturing method according to claim 6, characterized in that: The thickness of the first metal layer (4a) is smaller than the thickness of the first sacrificial layer (3a), and the thickness of the second metal layer (4b) is smaller than the thickness of the second sacrificial layer (3b).

8. The method according to claim 7, characterized in that: Before the first sacrificial layer (3a) and the second sacrificial layer (3b) are peeled off and removed, the manufacturing method further comprises: performing chemical mechanical polishing and flattening treatment on the surfaces of the first metal layer (4a) and the first sacrificial layer (3a), and performing chemical mechanical polishing and flattening treatment on the surfaces of the second metal layer (4b) and the second sacrificial layer (3b).

9. An atomic gas chamber manufactured by the manufacturing method according to any one of claims 1 to 8.

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