A high-temperature insulating vacuum cavity and a preparation method thereof

Abstract

The application provides a high-temperature insulating vacuum cavity and a preparation method thereof, comprising a first wafer, a cavity, a second wafer, an insulating layer and a high-temperature metal getter film. The insulating layer with good insulation, high temperature resistance and consistent thermal expansion coefficient with the wafer is used as a bonding intermediate layer, so that the high-temperature insulation performance of the bonded wafer is improved, and the problem of bonding failure caused by thermal expansion mismatch between the insulating layer and the wafer material at high temperature is avoided. The high-temperature metal getter film is attached to the insulating layer in the cavity, does not affect the bonding and insulation performance of the two wafers, and solves the problems of space occupation and easy generation of small particle pollution of the conventional bulk getter. The high-temperature annealing process enhances the wafer bonding strength on the one hand and activates the getter on the other hand, absorbs the residual gas in the cavity and maintains the vacuum degree, so that the vacuum degree of the bonding cavity is further improved. The cavity has good high-temperature insulation and high vacuum degree, and meets the preparation requirements of the capacitive high-temperature pressure sensor with a range lower than 100 kPa.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of micro-mechanical electronic technology, and in particular to a high-temperature insulating vacuum cavity and a preparation method thereof. BACKGROUND

[0002] Capacitive high-temperature pressure sensors are widely used in pressure measurement in harsh environments. Two wafers made of high-temperature materials (one of which is etched with a groove) are bonded to form an insulating capacitive cavity. Since the temperature of the sensor measuring point is high, the vacuum degree of the capacitive cavity is required. The vacuum degree is directly related to the measurement accuracy of the pressure sensor in a high-temperature environment. It is difficult to prepare a high-vacuum insulating cavity by using ordinary semiconductor bonding technology.

[0003] CN 103991840 B invention patent proposes a SiC absolute pressure cavity preparation method for ultra-high temperature environment. HF acid is used to remove the intrinsic oxide layer on the surface of SiC. A SiC absolute pressure cavity for high-temperature environment is prepared by hot-pressing annealing, which improves the vacuum degree (residual gas in the cavity is less than 1 kPa) and temperature resistance (higher than 1200℃) of the SiC absolute pressure cavity. However, this method cannot realize the insulation between SiC and SiC.

[0004] CN 102502482 B invention patent proposes a SiC-SiC vacuum bonding method with a cavity. PSG is deposited on the SiC wafer, and the PSG is polished to reduce the roughness. After activation, pre-bonding and high-temperature annealing are performed to realize the vacuum bonding of the SiC-SiC insulating cavity. However, the Si-O-Si bond is formed during the hydrophilic bonding of PSG, which releases oxygen and causes residual gas in the cavity. The residual gas amount is about 20 kPa to 40 kPa, which cannot meet the requirements of SiC capacitive pressure sensor preparation with a range of less than 100 kPa.

[0005] Therefore, there is an urgent need for a high-vacuum insulating cavity and a preparation method thereof. SUMMARY

[0006] The application aims to solve the problem of preparation of a vacuum cavity, and provides a high-temperature insulating vacuum cavity and a preparation method thereof, which uses an insulating layer with good insulation, high temperature resistance and consistent thermal expansion coefficient with the wafer as a bonding intermediate layer, thereby improving the high-temperature insulating performance of the bonding sheet and avoiding the problem of bonding failure caused by thermal expansion mismatch between the insulating layer and the wafer material at high temperature; the high-temperature metal getter film is attached to the insulating layer in the cavity, without affecting the bonding and insulating performance of the two wafers, thereby solving the problem of space occupation and easy generation of small particle pollution of conventional bulk getter; the high-temperature annealing process enhances the wafer bonding strength on the one hand and activates the getter on the other hand, thereby absorbing the residual gas in the cavity and maintaining the vacuum degree, so that the vacuum degree of the wafer bonding cavity is further improved. The cavity has good high-temperature insulation and high vacuum degree, and meets the preparation requirements of a capacitive high-temperature pressure sensor with a range less than 100 kPa.

[0007] The application provides a high-temperature insulating vacuum cavity, which comprises a first wafer, a cavity etched in the middle of the first wafer, a second wafer arranged on the upper part of the first wafer, an insulating layer bonded between the first wafer and the second wafer, and a high-temperature metal getter film arranged on the bottom surface of the cavity, the insulating layer is used as an intermediate layer for bonding the first wafer and the second wafer, and the high-temperature metal getter film is used to absorb the residual gas in the cavity after being activated during high-temperature annealing.

[0008] The high-temperature insulating vacuum cavity provided by the application is preferably provided with an insulating layer on the bottom surface and the side surface of the cavity, the high-temperature metal getter film is arranged on the upper part of the insulating layer on the bottom surface of the cavity, the thermal expansion coefficient of the insulating layer matches that of the first wafer and the second wafer, and the cavity is an insulating vacuum cavity.

[0009] The first wafer and the second wafer are both made of SiC.

[0010] The insulating layer is made of aluminum nitride, and the thickness of the insulating layer is less than that of the first wafer and the second wafer.

[0011] The high-temperature insulating vacuum cavity provided by the application is preferably provided with an insulating layer on the bottom surface and the side surface of the cavity, the high-temperature metal getter film is arranged on the upper part of the insulating layer on the bottom surface of the cavity, the thermal expansion coefficient of the insulating layer matches that of the first wafer and the second wafer, and the cavity is an insulating vacuum cavity.

[0012] The high-temperature insulating vacuum cavity provided by the application is preferably provided with an insulating layer on the bottom surface and the side surface of the cavity, the high-temperature metal getter film is arranged on the upper part of the insulating layer on the bottom surface of the cavity, the thermal expansion coefficient of the insulating layer matches that of the first wafer and the second wafer, and the cavity is an insulating vacuum cavity.

[0013] The application provides a preparation method of a high-temperature insulating vacuum cavity, which comprises the following steps:

[0014] S1, drying after cleaning the first wafer and the second wafer;

[0015] S2, etching the upper part of the first wafer to obtain a cavity;

[0016] S3, depositing on the upper surface of the first wafer to obtain an insulation layer, and depositing the insulation layer on the bottom and the side of the cavity;

[0017] S4, polishing the insulation layer and the second wafer, then cleaning and bonding to obtain a high-temperature insulation vacuum cavity.

[0018] The preparation method of the high-temperature insulation vacuum cavity, as a preferred mode, further comprises a step SA between the step S3 and the step S4:

[0019] SA, depositing a high-temperature metal on the upper part of the insulation layer to obtain a high-temperature metal getter film, patterning the high-temperature metal getter film, and removing the high-temperature metal getter film except the bottom of the cavity, so that the high-temperature metal getter film is only located on the bottom surface of the cavity;

[0020] The step S4 further comprises a step S5:

[0021] S5, high-temperature annealing the high-temperature insulation vacuum cavity to activate the high-temperature metal getter, and the preparation of the high-temperature insulation vacuum cavity is completed.

[0022] The preparation method of the high-temperature insulation vacuum cavity, as a preferred mode, in the step S1, the materials of the first wafer and the second wafer are SiC;

[0023] In the step S2, the etching method is plasma etching;

[0024] In the step S3, the thermal expansion coefficient of the insulation layer matches the first wafer and the second wafer, the material of the insulation layer is aluminum nitride, and the deposition method of the insulation layer is magnetron sputtering or molecular beam epitaxy or metal organic chemical vapor deposition;

[0025] In the step S4, the surface roughness of the polished insulation layer and the second wafer is less than 0.5 nm, the cleaning method after polishing includes scrubbing in an alkaline solution, ultrasonic cleaning and standard cleaning, the bonding temperature is 400-450 DEG C, the pressure is 1800 N, the holding time is 60-120 min, and the second wafer and the insulation layer are dried after dry activation or wet activation before bonding.

[0026] The preparation method of the high-temperature insulation vacuum cavity, as a preferred mode, in the step SA, the material of the high-temperature metal getter is TiTa alloy, the preparation method of the high-temperature metal getter film is vacuum annealing after depositing Ti film and Ta film by magnetron sputtering in sequence, and the patterning method is obtained by depositing metal after photolithography patterning and then stripping.

[0027] In step S5, the process parameters of high-temperature annealing are compatible with the activation temperature of the high-temperature metal getter.

[0028] As a preferred mode, in step S5, the process parameters of high-temperature annealing are as follows: a temperature rising rate < 10℃ / min, a temperature 800℃-950℃, a holding time 3h-5h, an atmosphere air or Ar gas, and a temperature falling rate < 10℃ / min, and the high-temperature insulation vacuum cavity is taken out after the temperature falls to 100℃.

[0029] The technical solution of the present application is:

[0030] A preparation method of a high-temperature insulation vacuum cavity comprises the following steps:

[0031] (1) two SiC single crystal wafers are prepared, and after standard cleaning, they are dried;

[0032] (2) a cavity is formed on the first SiC wafer by plasma etching;

[0033] (3) an insulation layer is deposited on the first SiC wafer with the cavity etched;

[0034] (4) high-temperature metal is deposited on the insulation layer of the first SiC wafer, a certain pattern of high-temperature metal getter is formed, and the getter film is located in the cavity;

[0035] (5) the insulation layer on the first SiC wafer is polished;

[0036] (6) the second SiC wafer is polished;

[0037] (7) the two polished SiC wafers are cleaned and bonded;

[0038] (8) the bonded wafer is high-temperature annealed and the getter is activated.

[0039] The shape of the cavity in step (2) can be circular or square, and the size is generally 2mm-3mm, which is determined according to the sensor range; the etching cavity depth is determined according to the sensor range, and is generally 1μm-10μm.

[0040] The insulation layer in step (3) is an aluminum nitride film with a thickness of 100nm-500nm, which can be prepared by magnetron sputtering, molecular beam epitaxy, metal organic chemical vapor deposition, etc.

[0041] The pattern of the high-temperature metal getter in step (4) can be circular or square, and is smaller than the size of the cavity; the high-temperature metal getter is a TiTa alloy, which is formed by vacuum annealing after Ti and Ta films are deposited in sequence by a magnetron sputtering method; and the patterned high-temperature metal getter film is formed by using a stripping process.

[0042] In step (5), the insulating layer on the first SiC wafer is polished, and the surface roughness after polishing is required to be less than 0.5 nm.

[0043] In step (6), the second SiC wafer is polished, and the surface roughness after polishing is required to be less than 0.5 nm.

[0044] In step (7), the polishing is followed by cleaning including scrubbing in an alkaline solution, ultrasonic cleaning and standard cleaning; and the wafer surface is activated by using a dry activation method or a wet activation method followed by spin-drying before bonding;

[0045] In step (8), the high-temperature annealing process parameters after bonding need to be compatible with the activation temperature of the getter, so as to ensure the bonding strength and the gettering effect.

[0046] The present application has the following advantages:

[0047] (1) The present application uses an insulating layer with good insulation, high temperature resistance and consistent thermal expansion coefficient with the wafer as the bonding intermediate layer, thereby improving the high-temperature insulation performance of the bonded wafer and avoiding the problem of bonding failure caused by thermal expansion mismatch between the insulating layer and the wafer material at high temperature.

[0048] (2) The high-temperature metal getter film used in the present application is attached to the insulating layer in the cavity, which does not affect the bonding and insulation performance of the two wafers, and solves the problem of space occupation and easy generation of small particle pollution of conventional bulk getter.

[0049] (3) The high-temperature annealing process used in the present application enhances the wafer bonding strength on the one hand, and activates the getter on the other hand, absorbs the residual gas in the cavity and maintains the vacuum degree, so that the vacuum degree of the wafer bonding cavity is further improved.

[0050] (4) The present application realizes the preparation of a high-temperature insulating vacuum cavity, has strong process compatibility and is easy to implement, and can be used for the preparation of a capacitive high-temperature pressure sensor with a range lower than 100 kPa. BRIEF DESCRIPTION OF DRAWINGS

[0051] Figure 1 Fig. 1 is a structural schematic diagram of a high-temperature insulating vacuum cavity;

[0052] Figure 2 Fig. 2 is a flow chart of a preparation method of a high-temperature insulating vacuum cavity;

[0053] Figure 3aA process flow chart of step S2 of the preparation method of the high-temperature insulation vacuum cavity is sputtering a metal mask film;

[0054] Figure 3b A process flow chart of step S2 of the preparation method of the high-temperature insulation vacuum cavity is spin coating a photoresist;

[0055] Figure 3c A process flow chart of step S2 of the preparation method of the high-temperature insulation vacuum cavity is etching the photoresist to form a cavity pattern;

[0056] Figure 3d A process flow chart of step S2 of the preparation method of the high-temperature insulation vacuum cavity is etching the metal mask film to form a cavity pattern;

[0057] Figure 3e A process flow chart of step S2 of the preparation method of the high-temperature insulation vacuum cavity is removing the photoresist and etching to form a cavity;

[0058] Figure 3f A process flow chart of step S2 of the preparation method of the high-temperature insulation vacuum cavity is removing the metal mask film;

[0059] Figure 4 A process flow chart of step S3 of the preparation method of the high-temperature insulation vacuum cavity is depositing an insulation layer;

[0060] Figure 5a A process flow chart of step S4 of the preparation method of the high-temperature insulation vacuum cavity is spraying a glue on the insulation layer;

[0061] Figure 5b A process flow chart of step S4 of the preparation method of the high-temperature insulation vacuum cavity is photoetching to form a high-temperature metal getter film pattern;

[0062] Figure 5c A process flow chart of step S4 of the preparation method of the high-temperature insulation vacuum cavity is sputtering a high-temperature metal getter;

[0063] Figure 5d A process flow chart of step S4 of the preparation method of the high-temperature insulation vacuum cavity is peeling.

[0064] Reference signs:

[0065] 1. first wafer; 2. cavity; 3. second wafer; 4. insulation layer; 5. high-temperature metal getter film. DETAILED DESCRIPTION

[0066] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments.

[0067] Example 1

[0068] like Figure 1 As shown, a high-temperature insulating vacuum cavity includes a first wafer 1, a cavity 2 etched in the middle of the first wafer 1, a second wafer 3 disposed on the upper part of the first wafer 1, an insulating layer 4 bonded between the first wafer 1 and the second wafer 3, and a high-temperature metal getter film 5 disposed on the bottom surface of the cavity 2. The insulating layer 4 is used as an intermediate layer for bonding the first wafer 1 and the second wafer 3.

[0069] Insulating layers 4 are also provided on the bottom and sides of cavity 2. The thermal expansion coefficient of insulating layer 4 is matched with that of the first wafer 1 and the second wafer 3. Cavity 2 is an insulating vacuum cavity.

[0070] The first wafer 1 and the second wafer 3 are both made of SiC.

[0071] The insulating layer 4 is made of aluminum nitride, and the thickness of the insulating layer 4 is less than the thickness of the first wafer 1 and the second wafer 3.

[0072] The high-temperature metal getter film 5 is used to absorb residual gas inside the cavity 2 after being activated during high-temperature annealing;

[0073] A high-temperature metal getter film 5 is disposed on the upper part of the insulating layer 4 located on the bottom surface of the cavity 2;

[0074] The cross-sectional shape of cavity 2 is circular or square, and the shape of high-temperature metal getter film 5 is circular or square, with a size smaller than the bottom surface size of cavity 2;

[0075] The high-temperature metal getter film 5 is made of TiTa alloy. The preparation method of the high-temperature metal getter film 5 is to deposit Ti film and Ta film sequentially by magnetron sputtering and then perform vacuum annealing.

[0076] Example 2

[0077] like Figure 1 As shown, a high-temperature insulating vacuum cavity includes a first wafer 1, a cavity 2 etched in the middle of the first wafer 1, a second wafer 3 disposed on the upper part of the first wafer 1, an insulating layer 4 bonded between the first wafer 1 and the second wafer 3, and a high-temperature metal getter film 5 disposed on the bottom surface of the cavity 2. The insulating layer 4 is used as an intermediate layer for bonding the first wafer 1 and the second wafer 3.

[0078] The first wafer 1 and the second wafer 3 are both made of SiC.

[0079] Insulating layers 4 are also provided on the bottom and sides of cavity 2. The thermal expansion coefficient of insulating layer 4 is matched with that of the first wafer 1 and the second wafer 3. Cavity 2 is an insulating vacuum cavity.

[0080] The shape of the cavity 2 can be circular or square, and the size is generally 2mm-3mm, which is determined according to the sensor range; the etching depth of the cavity 2 is determined according to the sensor range, and is generally 1-10μm;

[0081] The insulating layer is an aluminum nitride film with a thickness of 100-500nm, which can be prepared by magnetron sputtering, molecular beam epitaxy or metal organic chemical vapor deposition.

[0082] The pattern of the high-temperature metal getter 5 can be circular or square, and the high-temperature metal getter 5 is a TiTa alloy, which is formed by sequentially depositing Ti and Ta films by magnetron sputtering and then vacuum annealing; the patterning method of the high-temperature metal getter film is a peeling process.

[0083] Embodiment 3

[0084] As shown in Fig. 5, a method for preparing a high-temperature insulating vacuum cavity comprises the following steps: Figure 2

[0085] S1, cleaning and drying the first SiC wafer 1 and the second wafer 3;

[0086] The materials of the first wafer 1 and the second wafer 3 are both SiC;

[0087] S2, etching the upper part of the first SiC wafer 1 to obtain the cavity 2; the etching method is plasma etching;

[0088] S3, depositing on the upper surface of the first SiC wafer 1 to obtain the insulating layer 4, and also depositing the insulating layer 4 on the bottom and the side of the cavity 2;

[0089] The thermal expansion coefficient of the insulating layer 4 matches that of the first wafer 1 and the second wafer 3, the material of the insulating layer 4 is aluminum nitride, and the deposition method of the insulating layer 4 is magnetron sputtering, molecular beam epitaxy or metal organic chemical vapor deposition;

[0090] SA, depositing high-temperature metal on the upper part of the insulating layer 4 to obtain a high-temperature metal getter film 5, patterning the high-temperature metal getter film 5, removing the high-temperature metal getter film 5 except the bottom of the cavity 2, so that the high-temperature metal getter film 5 is only located on the bottom surface of the cavity 2;

[0091] The material of the high-temperature metal getter is a TiTa alloy, the preparation method of the high-temperature metal getter film 5 is vacuum annealing after sequentially depositing Ti and Ta films by magnetron sputtering, and the patterning method is photolithography, metal deposition and peeling;

[0092] S4, polishing the insulating layer 4 and the second wafer 3, and then cleaning and bonding to obtain a SiC high-temperature insulating vacuum cavity;

[0093] ​The surface roughness of the insulating layer 4 and the second wafer 3 after polishing is less than 0.5 nm, the polishing and cleaning method after polishing comprises scrubbing in an alkaline solution, ultrasonic cleaning and standard cleaning, the bonding temperature is 400-450 DEG C, the pressure is 1800 N, and the holding time is 60-120 min, the second wafer 3 and the insulating layer 4 are dry-activated or wet-activated and then dried before bonding;

[0094] S5, the SiC high-temperature insulating vacuum cavity is high-temperature annealed to activate the high-temperature metal getter film 5, and a high-temperature insulating vacuum cavity is prepared;

[0095] The process parameters of high-temperature annealing are compatible with the activation temperature of the high-temperature metal getter;

[0096] The process parameters of high-temperature annealing are as follows: the heating rate is less than 10 DEG C / min, the temperature is 800-950 DEG C, the holding time is 3-5 h, the atmosphere is air or Ar, and the cooling rate is less than 10 DEG C / min, and the SiC high-temperature insulating vacuum cavity is taken out when the temperature drops to 100 DEG C.

[0097] Embodiment 4

[0098] As shown in Figure 2 , a preparation method of a high-temperature insulating vacuum cavity comprises the following process steps:

[0099] (1) two 4-inch 4H-SiC wafers are prepared, cleaned by a standard cleaning process and dried.

[0100] (2) a cavity 2 is etched on the first SiC wafer 1. As shown in Figures 3a to 3f , the specific process steps are as follows: a metal mask film of a certain thickness of Ti and Ni is used on the SiC wafer 1 by magnetron sputtering, a positive photoresist is spin-coated, a pattern of the cavity 2 is formed by photoetching, the photoresist is used as a mask film, the metal mask film is etched to form the pattern of the cavity 2 by using dilute HNO3 and dilute HF in sequence, the photoresist is removed by using acetone, the cavity 2 is formed by plasma etching, and the metal mask film is removed by using dilute HNO3 and dilute HF after etching.

[0101] The thickness of the Ti is 20 nm, and the thickness of the Ni is not less than 500 nm; the cavity 2 is circular, and the diameter is 2-3 mm; SF6 and O2 are used for ICP etching of the SiC, and the etching rate is 500 nm / min; and the etching depth of the cavity 2 is 1-10 μm.

[0102] (3) the insulating layer 4 is deposited on the first SiC wafer 1 with the cavity 2. As shown in Figure 4 , the insulating layer 4 is an aluminum nitride film.

[0103] The growth of aluminum nitride film can use magnetron sputtering, molecular beam epitaxy, metal organic chemical vapor deposition, etc. The commonly used is magnetron sputtering method, 99.999% aluminum target and nitrogen reaction, sputtering power 150W, substrate temperature 550℃, deposition rate about 10-20nm / min, deposition thickness 100nm-500nm, film surface roughness about 1nm.

[0104] (4) Prepare high-temperature metal getter 5 on the insulating layer 4 of the cavity 2 of the first SiC wafer 1. As shown in Figures 5a to 5d , the specific process is: spray glue photoresist on the insulating layer 4 of the SiC wafer 1, photoetch a certain pattern of high-temperature metal getter 5, then magnetron sputtering deposition of high-temperature metal getter 5 on the whole wafer of SiC wafer 1, finally use peeling method in acetone solution to make high-temperature metal getter 5 only on the insulating layer 4 of the cavity 2.

[0105] Among them, a certain pattern of high-temperature metal getter 5 is a circle with a diameter of 1.5mm-2.5mm, smaller than the diameter of the cavity 2; high-temperature metal getter 5 is TiTa alloy, with a thickness of 500nm Ti and 300nm Ta, which forms after annealing at 750℃ in a high-temperature vacuum furnace for 1h.

[0106] (5) Polish the insulating layer 4 on the first SiC wafer 1 to reduce its roughness to less than 0.5nm. The equipment is CP-4 of Bruker, the polishing liquid is high-purity colloidal SiO2 suspension with a particle size of 50-80nm and a basic polishing liquid with PH=10-11; the polishing pad is IC1000, the polishing disc rotates at 80rpm, the polishing head rotates at 30rpm, the polishing pressure is 10-12 pounds, and the polishing time is 30-60min.

[0107] (6) Polish the second SiC wafer 3 to reduce its roughness to less than 0.5nm. The equipment is CP-4 of Bruker, the polishing liquid is an acidic polishing liquid with PH=2-3, the polishing pad is IC1000, the polishing disc rotates at 80rpm, the polishing head rotates at 30rpm, the polishing pressure is 10-12 pounds, and the polishing time is 30-60min.

[0108] (7) Clean and bond the two polished SiC wafers. The post-polishing cleaning includes scrubbing in alkaline solution, ultrasonic cleaning and standard cleaning; activate the surface of the insulating layer 4 on the first SiC wafer 1 and the second SiC wafer 3, which can be done by dry activation or wet activation followed by spin-drying; after activation, bond the two SiC wafers in a vacuum bonding machine, with bonding parameters of temperature 400-450℃, pressure 1800N, and holding time 60-120min.

[0109] (8) high temperature annealing is performed on the bonded wafer and getter activation is completed, so as to realize preparation of the SiC high temperature insulation vacuum cavity, as shown in FIG. 8. The specific process parameters are as follows: the temperature rising rate is <10℃ / min, the temperature is 800℃-950℃, the holding time is 3h-5h, the atmosphere is air or Ar gas, the temperature falling rate is <10℃ / min, and the bonded wafer is taken out after the temperature falls to 100℃. Figure 1

[0110] The helium mass spectrometer leak detector test shows that the leak rate of the bonded wafer is 3.5e-9atm.cm / s, the sealing performance of the bonded wafer meets the requirements, the high temperature insulation performance meets the requirements after 1200℃ temperature test, the vacuum degree in the cavity is lower than 1kPa, and the vacuum degree meets the requirements of the capacitive high temperature pressure sensor preparation with a range lower than 100kPa. 3

[0111] The insulating layer with good insulation, high temperature resistance and consistent thermal expansion coefficient with the wafer is used as the bonding intermediate layer, and the high temperature metal getter film is placed in the bonding cavity, so that the high temperature insulation performance and vacuum degree of the bonded wafer are greatly improved.

[0112] The above is only the preferred specific embodiment of the present application, but the protection scope of the present application is not limited to this, any skilled person in the art can make equivalent replacement or change according to the technical scheme and the inventive concept of the present application within the technical range disclosed by the present application, which should be covered in the protection scope of the present application.​​

Claims

1. A high temperature insulating vacuum cavity, characterized by: The high-temperature insulating vacuum cavity comprises a first wafer (1), a cavity (2) etched in the middle of the first wafer (1), a second wafer (3) arranged on the upper part of the first wafer (1), an insulating layer (4) deposited on the first wafer (1) and bonded with the second wafer (3), and a high-temperature metal getter film (5) arranged on the bottom surface of the cavity (2), wherein the insulating layer (4) is used as an intermediate layer for bonding the first wafer (1) and the second wafer (3), and the high-temperature metal getter film (5) is used to absorb residual gas in the cavity (2) after being activated during high-temperature annealing. The bottom surface and the side surface of the cavity (2) are also provided with the insulating layer (4), and the high-temperature metal getter film (5) is arranged on the upper part of the insulating layer (4) arranged on the bottom surface of the cavity (2), the thermal expansion coefficient of the insulating layer (4) matches the first wafer (1) and the second wafer (3), and the cavity (2) is an insulating vacuum cavity. The materials of the first wafer (1) and the second wafer (3) are SiC. The material of the insulating layer (4) is aluminum nitride, the thickness of the insulating layer (4) is less than the thickness of the first wafer (1) and the second wafer (3), and the thickness of the insulating layer (4) is 100-500 nm. The preparation method of the high-temperature metal getter film (5) is vacuum annealing after sequentially depositing Ti film and Ta film by magnetron sputtering. The bonding temperature is 400-450℃, the pressure is 1800N, the holding time is 60-120min, high-temperature annealing is performed after bonding, and the high-temperature metal getter film (5) is activated at the same time, the process parameters of high-temperature annealing are compatible with the activation temperature of the high-temperature metal getter, the process parameters of high-temperature annealing are as follows: the heating rate is less than 10℃ / min, the temperature is 800-950℃, the holding time is 3-5h, the atmosphere is air or Ar gas, and the cooling rate is less than 10℃ / min, and the high-temperature insulating vacuum cavity is taken out after the temperature drops to 100℃.

2. The high-temperature insulating vacuum cavity according to claim 1, wherein the cross-sectional shape of the cavity (2) is circular or square, and the shape of the high-temperature metal getter film (5) is circular or square, and the size of the high-temperature metal getter film (5) is smaller than the size of the bottom surface of the cavity (2). The preparation method comprises the following steps:

3. A high temperature insulated vacuum cavity according to claim 1, characterized in that: S1, cleaning and drying the first wafer (1) and the second wafer (3); S2, etching the cavity (2) on the upper part of the first wafer (1), specifically, using a magnetron sputtering metal mask film on the first wafer (1), the metal mask film is Ti or Ni with a specified thickness, spin-coating positive photoresist, and performing photoetching to form a pattern of the cavity (2); using HNO3 and HF to etch the metal mask film to form the pattern of the cavity (2), and removing the photoresist by using acetone; and performing plasma etching to form the cavity (2); and removing the metal mask film by using HNO3 and HF after the etching is completed; ​ S3, depositing an insulating layer (4) on the upper surface of the first wafer (1), the bottom and the side of the cavity (2) are also deposited with the insulating layer (4); SA, depositing a high-temperature metal on the upper part of the insulating layer (4) to obtain a high-temperature metal getter film (5), patterning the high-temperature metal getter film (5), removing the high-temperature metal getter film (5) except the bottom of the cavity (2), so that the high-temperature metal getter film (5) is only located on the bottom surface of the cavity (2); S4, polishing the insulating layer (4) and the second wafer (3), then cleaning and bonding to obtain a high-temperature insulating vacuum cavity; S5, high-temperature annealing the high-temperature insulating vacuum cavity, and simultaneously activating the high-temperature metal getter film (5), thereby completing the preparation of a high-temperature insulating vacuum cavity.

4. The high-temperature insulating vacuum cavity according to claim 3, wherein: In step S2, the etching method is plasma etching; In step S3, the deposition method of the insulating layer (4) is magnetron sputtering, molecular beam epitaxy or metal organic chemical vapor deposition; In step S4, the surface roughness of the polished insulating layer (4) and the second wafer (3) is less than 0.5 nm, the insulating layer (4) is polished using a colloidal SiO2 suspension with a pH of 10-11 as a polishing liquid, and the second wafer (3) is polished using an acidic polishing liquid with a pH of 2-3; The cleaning method after polishing includes scrubbing in an alkaline solution, ultrasonic cleaning and standard cleaning, and the second wafer (3) and the insulating layer (4) are subjected to dry activation or wet activation before bonding.

5. A high temperature insulated vacuum cavity according to claim 3, wherein: In step SA, the patterning method is photolithographic patterning, followed by metal deposition and stripping.

Images