CN112736167B - Composite substrate, composite film, preparation method of composite film and radio frequency filter - Google Patents
Composite substrate, composite film, preparation method of composite film and radio frequency filter Download PDFInfo
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- 239000000758 substrate Substances 0.000 title claims abstract description 127
- 239000002131 composite material Substances 0.000 title claims abstract description 92
- 238000002360 preparation method Methods 0.000 title abstract description 10
- 229910021421 monocrystalline silicon Inorganic materials 0.000 claims abstract description 134
- 229910021420 polycrystalline silicon Inorganic materials 0.000 claims abstract description 109
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 85
- 230000004927 fusion Effects 0.000 claims abstract description 58
- 239000013078 crystal Substances 0.000 claims abstract description 44
- 235000012239 silicon dioxide Nutrition 0.000 claims abstract description 43
- 239000000377 silicon dioxide Substances 0.000 claims abstract description 42
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 14
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 13
- 239000010703 silicon Substances 0.000 claims abstract description 13
- 239000010408 film Substances 0.000 claims description 81
- 238000000034 method Methods 0.000 claims description 57
- 239000010409 thin film Substances 0.000 claims description 37
- 229920005591 polysilicon Polymers 0.000 claims description 35
- GQYHUHYESMUTHG-UHFFFAOYSA-N lithium niobate Chemical compound [Li+].[O-][Nb](=O)=O GQYHUHYESMUTHG-UHFFFAOYSA-N 0.000 claims description 31
- 238000005498 polishing Methods 0.000 claims description 28
- WSMQKESQZFQMFW-UHFFFAOYSA-N 5-methyl-pyrazole-3-carboxylic acid Chemical compound CC1=CC(C(O)=O)=NN1 WSMQKESQZFQMFW-UHFFFAOYSA-N 0.000 claims description 21
- 238000005468 ion implantation Methods 0.000 claims description 21
- 238000010438 heat treatment Methods 0.000 claims description 19
- 238000000926 separation method Methods 0.000 claims description 18
- 230000003647 oxidation Effects 0.000 claims description 17
- 238000007254 oxidation reaction Methods 0.000 claims description 17
- JBRZTFJDHDCESZ-UHFFFAOYSA-N AsGa Chemical compound [As]#[Ga] JBRZTFJDHDCESZ-UHFFFAOYSA-N 0.000 claims description 4
- 229910001218 Gallium arsenide Inorganic materials 0.000 claims description 4
- 229910019142 PO4 Inorganic materials 0.000 claims description 3
- 229910052732 germanium Inorganic materials 0.000 claims description 3
- GNPVGFCGXDBREM-UHFFFAOYSA-N germanium atom Chemical compound [Ge] GNPVGFCGXDBREM-UHFFFAOYSA-N 0.000 claims description 3
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 claims description 3
- 239000010452 phosphate Substances 0.000 claims description 3
- WYOHGPUPVHHUGO-UHFFFAOYSA-K potassium;oxygen(2-);titanium(4+);phosphate Chemical compound [O-2].[K+].[Ti+4].[O-]P([O-])([O-])=O WYOHGPUPVHHUGO-UHFFFAOYSA-K 0.000 claims description 3
- 229910052701 rubidium Inorganic materials 0.000 claims description 3
- IGLNJRXAVVLDKE-UHFFFAOYSA-N rubidium atom Chemical compound [Rb] IGLNJRXAVVLDKE-UHFFFAOYSA-N 0.000 claims description 3
- BLRPTPMANUNPDV-UHFFFAOYSA-N Silane Chemical compound [SiH4] BLRPTPMANUNPDV-UHFFFAOYSA-N 0.000 claims 1
- 238000005520 cutting process Methods 0.000 abstract description 8
- 150000001875 compounds Chemical class 0.000 abstract 2
- 229910021419 crystalline silicon Inorganic materials 0.000 abstract 1
- 239000010410 layer Substances 0.000 description 248
- 238000004321 preservation Methods 0.000 description 19
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- 238000002955 isolation Methods 0.000 description 11
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- 239000007789 gas Substances 0.000 description 8
- 239000001307 helium Substances 0.000 description 8
- 229910052734 helium Inorganic materials 0.000 description 8
- -1 hydrogen ions Chemical class 0.000 description 8
- 239000000463 material Substances 0.000 description 8
- 238000010897 surface acoustic wave method Methods 0.000 description 7
- 238000010586 diagram Methods 0.000 description 6
- 238000002513 implantation Methods 0.000 description 6
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- 239000011261 inert gas Substances 0.000 description 5
- 150000002500 ions Chemical class 0.000 description 5
- 229910052757 nitrogen Inorganic materials 0.000 description 5
- 230000001681 protective effect Effects 0.000 description 5
- 238000004518 low pressure chemical vapour deposition Methods 0.000 description 4
- 238000004140 cleaning Methods 0.000 description 3
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 2
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 2
- 239000001257 hydrogen Substances 0.000 description 2
- 229910052739 hydrogen Inorganic materials 0.000 description 2
- 239000002346 layers by function Substances 0.000 description 2
- 230000001590 oxidative effect Effects 0.000 description 2
- 230000002035 prolonged effect Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 230000017525 heat dissipation Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
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- 238000004806 packaging method and process Methods 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L33/02—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
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Abstract
The application provides a composite substrate, a composite film, a preparation method of the composite film and a radio frequency filter, wherein the composite substrate sequentially comprises a crystalline silicon substrate layer and a first polycrystalline silicon layer from bottom to top, and the first polycrystalline silicon layer comprises a monocrystalline silicon fusion layer, a second polycrystalline silicon layer and a silicon dioxide layer; the monocrystalline silicon fusion layer and the monocrystalline silicon substrate layer are integrally formed; a fusion bulge is formed on one side of the monocrystalline silicon fusion layer close to the second polycrystalline silicon layer; the monocrystalline silicon substrate layer, the monocrystalline silicon fusion layer and the fusion protrusion have the same crystal orientation. This application improves the adhesion of second polycrystalline silicon layer deposit on the silicon substrate through forming the monocrystalline silicon fusion layer between second polycrystalline silicon layer and monocrystalline silicon substrate layer, reduces the risk that the bonding is separated to the compound film takes place at the relatively poor interface of cohesion in cutting process, avoids the functional film to drop, improves the utilization ratio of compound film, reduces the risk that the bonding was separated in the radio frequency filter use simultaneously, prolongs radio frequency filter's life.
Description
Technical Field
The present disclosure relates to the field of semiconductor technologies, and in particular, to a composite substrate, a composite film, a method for manufacturing the composite film, and a radio frequency filter.
Background
Radio frequency filters are widely used in the transceiving links of wireless communication terminals to allow signals of a specific frequency or frequency band to pass through while filtering out unwanted interference or spurious signals. The rf filters mainly include surface acoustic wave filters (SAW filters) and bulk acoustic wave filters (BAW filters), which range in frequency from 800 to 2500 MHz. The energy of surface acoustic waves in the surface acoustic wave filter is focused on the surface of the substrate, so that the waves are transmitted on the substrate without loss, the linear expansion coefficient of the substrate and the speed of sound are controlled simultaneously to reduce the frequency temperature coefficient, and the heat generated by the electrodes is transmitted to the substrate, so that the surface acoustic wave filter has good heat dissipation performance, and the frequency response stability of the surface acoustic wave filter at high temperature is ensured.
Surface acoustic wave filters generally use a lithium tantalate thin film on silicon as a device substrate. Wherein, the silicon is used as a supporting substrate, the silicon dioxide is used as an isolating layer, and the lithium tantalate piezoelectric film layer is used as a functional layer to form the lithium tantalate film wafer. In order to reduce the rf loss of the saw filter and improve the performance of the saw filter, a polysilicon layer is usually added between a silicon substrate and a silicon dioxide isolation layer to reduce the number of carriers between the silicon substrate and the silicon dioxide isolation layer. Processing electrodes on the lithium tantalate thin film wafer, then cutting the whole wafer with the processed electrodes into fixed sizes according to requirements, and finally packaging.
However, the size of the surface acoustic wave filter is smaller, and the cutting size of the lithium tantalate film wafer is smaller, so the bonding force between layers of the lithium tantalate film wafer becomes a key factor of the utilization rate of the lithium tantalate film and the yield of devices. If the adhesion of the polycrystalline silicon deposited on the silicon substrate is poor, the bonding force of the lithium tantalate film is poor, the lithium tantalate film is easy to be debonded on an interface with poor bonding force in the cutting process, so that the lithium tantalate film falls off, and the use of the area is influenced; in addition, the weak bonding force can also increase the risk of debonding in the use process of the radio frequency filter, and reduce the service life of the radio frequency filter.
Disclosure of Invention
The application provides a composite substrate, a composite film, a preparation method of the composite film and a radio frequency filter, which aim to solve the problem that in the prior art, the composite film is easy to be debonded at an interface with poor bonding force in the cutting process, so that a functional film falls off and the use of the area is influenced; in addition, the weak bonding force can also increase the risk of debonding in the use process of the radio frequency filter, and reduce the service life of the radio frequency filter.
In a first aspect of the present application, the present application provides a composite substrate, which sequentially includes, from bottom to top, a monocrystalline silicon substrate layer and a first polycrystalline silicon layer, where the first polycrystalline silicon layer includes a monocrystalline silicon fusion layer, a second polycrystalline silicon layer, and a silicon dioxide layer;
wherein the monocrystalline silicon fusion layer and the monocrystalline silicon substrate layer are integrally formed; a fusion bulge is formed on one side of the monocrystalline silicon fusion layer close to the second polycrystalline silicon layer; the monocrystalline silicon substrate layer, the monocrystalline silicon fusion layer and the fusion protrusion are the same in crystal orientation.
Optionally, the monocrystalline silicon fusion layer is formed by oxidation of the first polycrystalline silicon layer.
Optionally, the thickness of the monocrystalline silicon fusion layer is greater than or equal to 1nm and less than or equal to 20 nm.
Optionally, the thickness of the second polysilicon layer is greater than or equal to 100nm and less than or equal to 3 μm.
Optionally, the length of the fusion projection is greater than or equal to 5nm and less than or equal to 20 nm; the width of the fusion projection is more than or equal to 1nm and less than or equal to 20 nm.
In a second aspect of the present application, a composite film is provided, which comprises, from bottom to top, a composite substrate and a functional thin film layer as in any one of the first aspect, wherein the upper surface of the composite substrate is planarized, and the composite substrate can be bonded to the functional thin film layer.
Optionally, the functional thin film layer is a lithium niobate crystal, a lithium tantalate crystal, a rubidium titanyl phosphate crystal, a potassium titanyl phosphate crystal, a silicon crystal, a germanium crystal or a gallium arsenide crystal.
In a third aspect of the present application, there is provided a radio frequency filter comprising the composite film according to any one of the second aspect.
In a fourth aspect of the present application, there is provided a method for preparing a composite film, including:
growing polycrystalline silicon on the monocrystalline silicon substrate layer, and flattening the polycrystalline silicon to a first target thickness to form a first polycrystalline silicon layer;
placing the monocrystalline silicon substrate layer and the first polycrystalline silicon layer in an oxidation furnace and heating to obtain a composite substrate; the composite substrate sequentially comprises a monocrystalline silicon substrate layer, a monocrystalline silicon fusion layer, a second polycrystalline silicon layer and a silicon dioxide layer from bottom to top;
planarizing the silicon dioxide layer to a second target thickness;
and preparing a functional film layer on the flattened silicon dioxide layer to obtain the composite film.
Optionally, the growing polycrystalline silicon on the monocrystalline silicon substrate layer and planarizing the polycrystalline silicon to a first target thickness to obtain a first polycrystalline silicon layer includes:
introducing SiH gas into the monocrystalline silicon substrate layer at a temperature of 580 deg.C or higher and 650 deg.C or lower and under a pressure of 0.1Torr or higher and 0.4Torr or lower4Growing polysilicon with the thickness of 1.8 mu m;
and mechanically polishing the polysilicon to 1.4 mu m to obtain a first polysilicon layer.
Optionally, the step of placing the monocrystalline silicon substrate layer and the first polycrystalline silicon layer in an oxidation furnace and heating to obtain a composite substrate includes:
and placing the monocrystalline silicon substrate layer and the first polycrystalline silicon layer in an oxidation furnace with the temperature of more than or equal to 800 ℃ and less than or equal to 1000 ℃ for heating for at least 10h and at most 30h to obtain the composite substrate.
Optionally, the functional thin film layer is prepared on the isolation layer by combining an ion implantation method with a bonding separation method, or by combining a bonding method with a grinding polishing method.
The application provides a composite substrate, a composite film, a preparation method of the composite film and a radio frequency filter, wherein the composite substrate sequentially comprises a monocrystalline silicon substrate layer and a first polycrystalline silicon layer from bottom to top, and the first polycrystalline silicon layer comprises a monocrystalline silicon fusion layer, a second polycrystalline silicon layer and a silicon dioxide layer; wherein the monocrystalline silicon fusion layer and the monocrystalline silicon substrate layer are integrally formed; a fusion bulge is formed on one side of the monocrystalline silicon fusion layer close to the second polycrystalline silicon layer; the monocrystalline silicon substrate layer, the monocrystalline silicon fusion layer and the fusion protrusion are the same in crystal orientation. Adopt the scheme that this application provided, form monocrystalline silicon fusion layer between second polycrystalline silicon layer and monocrystalline silicon substrate layer, the polycrystalline silicon that the second polycrystalline silicon layer is close to monocrystalline silicon substrate layer one side is nucleated gradually, grow to monocrystalline silicon, monocrystalline silicon and monocrystalline silicon substrate layer integrated into one piece after the growth, improve the adhesion of second polycrystalline silicon layer deposit on the silicon substrate, reduce the risk that the bonding is separated to take place at the relatively poor interface of cohesion of composite film in cutting process, avoid the functional film to drop, improve composite film's utilization ratio, reduce the risk that the bonding was separated in the radio frequency filter use simultaneously, prolong radio frequency filter's life.
Drawings
In order to more clearly explain the technical solution of the present application, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious to those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a schematic structural diagram of a composite substrate provided in the present application;
FIG. 2 is a schematic structural diagram of a composite film provided herein;
FIG. 3 is a schematic flow chart of a method for preparing a composite film according to the present disclosure;
fig. 4 is a schematic structural diagram of a method for preparing a composite film provided by the present application.
The structure comprises a monocrystalline silicon substrate layer 110, a monocrystalline silicon fusion layer 120, a second polycrystalline silicon layer 130, a silicon dioxide layer 140, a fusion protrusion 150, a functional thin film layer 160 and a first polycrystalline silicon layer 170.
Detailed Description
The technical solutions in the embodiments of the present application will be described clearly and completely with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
As described in the background of the present application, in the prior art, the volume of the rf filter is small, and the size of the lithium tantalate thin film wafer to be cut is smaller, so the bonding force between layers of the lithium tantalate thin film wafer becomes a key factor of the utilization rate of the lithium tantalate thin film and the yield of the device. If the adhesion of the polycrystalline silicon deposited on the silicon substrate is poor, the bonding force of the lithium tantalate film is poor, and the lithium tantalate film wafer is easy to be debonded on the interface with poor bonding force in the cutting process, so that the lithium tantalate film falls off and the use of the area is influenced; in addition, the weak bonding force can also increase the risk of debonding in the use process of the radio frequency filter, and reduce the service life of the radio frequency filter.
Therefore, in order to solve the above problem, an embodiment of the present application provides a composite substrate, and referring to fig. 1, fig. 1 is a schematic structural diagram of a composite substrate provided in the present application, the composite substrate includes, from bottom to top, a monocrystalline silicon substrate layer 110 and a first polycrystalline silicon layer 170, the first polycrystalline silicon layer 170 includes a monocrystalline silicon fusion layer 120, a second polycrystalline silicon layer 130, and a silicon dioxide layer 140. The composite substrate provided by the application is not only suitable for composite films with lithium tantalate as a functional layer, but also suitable for composite films in other fields such as photoelectric modulation sensors.
The monocrystalline silicon fused layer 120 is formed integrally with the monocrystalline silicon substrate layer 110, and the monocrystalline silicon fused layer 120 is formed by oxidizing the first polycrystalline silicon layer 170 and then gradually nucleating the oxidized monocrystalline silicon, and the grown monocrystalline silicon is fused with the monocrystalline silicon substrate layer 110.
The single crystal silicon fused layer 120 is formed with a fused protrusion 150 on a side close to the second polysilicon layer 130, the single crystal silicon fused layer 120 is a mutual fused region where polysilicon is transformed into single crystal silicon, and the flatness of the single crystal silicon fused layer 120 cannot be controlled in the process of oxidizing the polysilicon at a high temperature, so that the surface of the single crystal silicon fused layer 120 is protruded.
The monocrystalline silicon substrate layer 110, the monocrystalline silicon fused layer 120, and the fused bumps 150 have the same crystalline orientation of the monocrystalline silicon.
The polycrystalline silicon on the side of the first polycrystalline silicon layer 170, which is far away from the monocrystalline silicon substrate layer 110, is oxidized to form the silicon dioxide layer 140, the oxidation temperature and the oxidation time are controlled, the polycrystalline silicon on the side close to the monocrystalline silicon substrate layer 110 is simultaneously oxidized to form the monocrystalline silicon fusion layer 120 with the same crystal orientation as the monocrystalline silicon substrate layer 110, the monocrystalline silicon fusion layer 120 and the monocrystalline silicon substrate layer 110 are integrated into a whole due to the same crystal orientation, the adhesion of the second polycrystalline silicon layer 130 and the monocrystalline silicon substrate layer 110 is further enhanced, the falling of a functional film is avoided, the utilization rate of a composite film is improved, the risk of bonding in the use process of the radio frequency filter is reduced, and the service life of the radio frequency filter is prolonged.
The embodiment of the application provides a composite substrate, which sequentially comprises a monocrystalline silicon substrate layer 110, a monocrystalline silicon fusion layer 120, a second polycrystalline silicon layer 130 and a silicon dioxide layer 140 from bottom to top; wherein, the monocrystalline silicon fusion layer 120 and the monocrystalline silicon substrate layer 110 are integrally formed; a fusion protrusion 150 is formed on one side of the monocrystalline silicon fusion layer 120 close to the second polycrystalline silicon layer 130; the monocrystalline silicon substrate layer 110, the monocrystalline silicon fused layer 120, and the fused bumps 150 have the same crystalline orientation of the monocrystalline silicon. By adopting the scheme provided by the embodiment of the application, the monocrystalline silicon fusion layer 120 is formed between the second polycrystalline silicon layer 130 and the monocrystalline silicon substrate layer 110, the polycrystalline silicon on one side of the second polycrystalline silicon layer 130 close to the monocrystalline silicon substrate layer 110 gradually nucleates to grow into monocrystalline silicon, the grown monocrystalline silicon forms the monocrystalline silicon fusion layer 120 and is integrally formed with the monocrystalline silicon substrate layer 110, the adhesion of the second polycrystalline silicon layer 130 deposited on the silicon substrate is improved, the risk of debonding of the composite film on the interface with poor bonding force in the cutting process is reduced, the falling of the functional film is avoided, the utilization rate of the composite film is improved, the debonding risk in the use process of the radio frequency filter is reduced, and the service life of the radio frequency filter is prolonged.
In one embodiment, the thickness of the monocrystalline silicon merged layer 120 is greater than or equal to 1nm and less than or equal to 20 nm.
The longer the time of the high-temperature oxidation of the polycrystalline silicon is, the larger the thickness of the monocrystalline silicon fusion layer 120 is, the thickness of the monocrystalline silicon fusion layer 120 is controlled to be greater than or equal to 1nm and less than or equal to 20nm, the resistivity between the monocrystalline silicon substrate layer 110 and the second polycrystalline silicon layer 130 is not affected by the monocrystalline silicon fusion layer 120 within the thickness range, the performance of capturing carriers by the second polycrystalline silicon layer 130 can be ensured, and in addition, the thickness uniformity of the composite film is not affected by the fusion protrusion 150 on the monocrystalline silicon fusion layer 120.
In one embodiment, the thickness of the second polysilicon layer 130 is greater than or equal to 100nm and less than or equal to 3 μm.
The defects in the second polysilicon layer 130 can capture carriers between the silicon dioxide layer 140 and the monocrystalline silicon substrate layer 110, reduce the number of carriers between the silicon dioxide layer 140 and the monocrystalline silicon substrate layer 110, and reduce the radio frequency loss of the radio frequency filter.
In one embodiment, the length of the fusion protrusion 150 is greater than or equal to 5nm and less than or equal to 20 nm; the width of the fusion protrusion 150 is greater than or equal to 1nm and less than or equal to 20nm, which is beneficial to improving the adhesion between the second polysilicon layer 130 and the monocrystalline silicon substrate layer 110.
Referring to fig. 2, fig. 2 is a schematic structural diagram of a composite film provided herein, based on the composite substrate provided in the foregoing embodiment of the present disclosure, an embodiment of the present disclosure further provides a composite film, where the composite film includes the composite substrate described in any one of the foregoing embodiments and a functional thin film layer 160, and an upper surface of the composite substrate is planarized and can be bonded to the functional thin film layer 160.
The material of the functional thin film layer 160 may be selected according to the function to be actually realized, and the functional thin film layer 160 may be a crystal having a piezoelectric function and a photoelectric function, such as a lithium niobate crystal, a lithium tantalate crystal, a rubidium titanyl phosphate crystal, a potassium titanyl phosphate crystal, a silicon crystal, a germanium crystal, or a gallium arsenide crystal.
The composite substrate provided by the embodiment of the application is applied to a composite film, and the composite film can reduce the number of current carriers between the monocrystalline silicon substrate layer 110 and the silicon dioxide layer 140 so as to reduce the radio frequency loss of the radio frequency filter, improve the performance of the radio frequency filter, and can be widely applied.
Based on the composite film provided by the foregoing embodiments of the present application, an embodiment of the present application also provides a radio frequency filter, where the radio frequency filter includes the composite film as described above.
The embodiment of the present application also provides a method for preparing the composite film, as shown in fig. 4, fig. 4 is a schematic structural diagram of the method for preparing the composite film.
Specifically, as shown in fig. 3, the preparation method comprises the following steps:
step S11, growing polysilicon on the monocrystalline silicon substrate layer 110, and planarizing the polysilicon to a first target thickness to form a first polysilicon layer 170;
optionally, in this step, LPVCD is used to introduce SiH gas into the monocrystalline silicon substrate layer 110 under the conditions of a temperature greater than or equal to 580 ℃, a temperature less than or equal to 650 ℃, a pressure greater than or equal to 0.1Torr, and a pressure less than or equal to 0.4Torr4Growing polysilicon with the thickness of 1.8 mu m; the polysilicon is mechanically polished to 1.4 μm, resulting in a first polysilicon layer 170.
Step S12, placing the monocrystalline silicon substrate layer 110 and the first polycrystalline silicon layer 170 in an oxidation furnace and heating to obtain a composite substrate; the composite substrate sequentially comprises a monocrystalline silicon substrate layer 110, a monocrystalline silicon fusion layer 120, a second polycrystalline silicon layer 130 and a silicon dioxide layer 140 from bottom to top;
optionally, in this step, the monocrystalline silicon substrate layer 110 and the first polycrystalline silicon layer 170 are placed in an oxidation furnace at a temperature of 800 ℃ or higher and 1000 ℃ or lower and heated for at least 10 hours and at most 30 hours, and the top and the bottom of the first polycrystalline silicon layer 170 are oxidized to form the silicon dioxide layer 140 and the monocrystalline silicon fusion layer 120, respectively, so as to obtain the composite substrate.
Step S13, planarizing the silicon dioxide layer 140 to a second target thickness;
optionally, in this step, the silicon dioxide layer 140 is polished by chemical mechanical polishing.
Step S14, a functional thin film layer 160 is prepared on the planarized silicon dioxide layer 140, and a composite thin film is obtained.
Optionally, in this step, the preparation method of the functional thin film layer 160 may select to combine an ion implantation method with a bonding separation method, or combine a bonding method with a grinding and polishing method, which is not specifically limited in this application.
When the ion implantation method is combined with the bonding separation method, the scheme comprises the following steps: performing ion implantation on the functional film to form a functional film wafer with a three-layer structure of a film layer, a separation layer and a residual material layer; preparing and forming a bonding body by adopting a plasma bonding mode; keeping the temperature of the bonding body at high temperature; wherein the heat preservation temperature is 100-600 ℃, and the heat preservation time is 1 min-48 h until the residual material layer is separated from the bonding body to form a single crystal film; polishing the single crystal film to 50nm-3000nm to obtain the single crystal film with nano-scale thickness.
The implanted ions are ions that can generate gas by heat treatment, and examples of the ions include: hydrogen ions or helium ions, and the implantation dose may be 3 × 1016ions/cm2-8×1016ions/cm2The implantation energy may be 120KeV-400 KeV; when implanting helium ions, the implantation dose can be 1 × 1016ions/cm2-1×1017ions/cm2The implantation energy may be 50KeV-1000 KeV. The thickness of the thin film layer is adjusted by adjusting the ion implantation depth, and specifically, the larger the ion implantation depth is, the larger the thickness of the prepared thin film layer is; conversely, the smaller the depth of ion implantation, the smaller the thickness of the thin film layer produced.
The purpose of the heat preservation of the bonding body is to improve the bonding force of the bonding body to be larger than 10MPa, and the damage of ion implantation to the thin film layer can be recovered, so that the obtained thin film layer is close to the property of a wafer. During the heat treatment, bubbles are formed in the separation layer, for example, hydrogen ions form hydrogen gas, helium ions form helium gas, and the like, and as the heat treatment progresses, the bubbles in the separation layer are connected into one piece, and finally the separation layer is cracked to separate the remaining layer from the thin film layer, so that the remaining layer is peeled off from the bonded body.
When the bonding method is combined with the grinding and polishing method, the scheme comprises the following steps: cleaning the process surface of the wafer, and bonding the process surface of the cleaned wafer and the silicon dioxide layer by adopting a plasma bonding method to form a bonded body; placing the bonding body into heating equipment, preserving heat at high temperature, and performing under a vacuum environment or under a protective atmosphere formed by at least one of nitrogen and inert gas; wherein the heat preservation temperature is 100-600 ℃, the heat preservation time is 1 min-48 h, and the bonding force of the bonding body can be improved by the link and is more than 10 MPa; thinning the film to 1-102 μm by mechanical grinding, and polishing to 400nm-100 μm to obtain a single crystal film with micron-sized thickness.
After ion implantation and before bonding, it is usually necessary to clean the two contacting bonding surfaces to enhance the bonding effect.
According to the preparation method disclosed by the embodiment of the application, the preparation method of the composite film is simple in process, easy to operate and suitable for large-scale popularization and application.
In the embodiments of the present application, the embodiments of the structural portion and the embodiments of the preparation method portion may be referred to each other, and are not described herein again.
In order to make the scheme of the application clearer, specific examples are further disclosed in the embodiment of the application.
Example 1 (ion implantation coupled bonding separation method)
1) Preparing a monocrystalline silicon substrate layer, introducing SiH gas into the monocrystalline silicon substrate layer by LPCVD under the conditions of 580 ℃ and 0.1Torr4And growing polysilicon with the thickness of 1.8 mu m.
2) Mechanically polishing the polysilicon in the step 1) to 1.4 mu m to obtain a first polysilicon layer.
3) And placing the monocrystalline silicon substrate layer and the first polycrystalline silicon layer in an oxidation furnace at the temperature of 1000 ℃ for heating for 15h to form a silicon dioxide layer with the thickness of 1200nm, a monocrystalline silicon fusion layer with the thickness of 10nm and a second polycrystalline silicon layer with the thickness of 500 nm.
4) Grinding and polishing the silicon dioxide layer in the step 3) to 1000 nm.
5) Preparing a lithium niobate wafer with the same size as the monocrystalline silicon substrate layer, and implanting helium ions (He +) into the lithium niobate wafer by using an ion implantation method, wherein the implantation energy of the helium ions is 200KeV, and the dosage is 4 multiplied by 1016ions/cm2And forming the lithium niobate wafer with a three-layer structure of a thin film layer, a separation layer and a residual material layer.
6) Bonding the thin film layer of the lithium niobate wafer after ion implantation with the silicon dioxide layer of the monocrystalline silicon substrate by adopting a plasma bonding method to form a bonded body; and then putting the bonding body into heating equipment, and preserving heat at high temperature until the residual material layer is separated from the bonding body to form the lithium niobate single crystal film. The heat preservation process is carried out in a vacuum environment or in a protective atmosphere formed by at least one of nitrogen and inert gas, the heat preservation temperature is 400 ℃, and the heat preservation time is 3 hours.
7) And polishing and thinning the lithium niobate single crystal film to 400nm to obtain the lithium niobate single crystal composite film with the nanoscale thickness.
It can be seen that, in example 1, a method of combining ion implantation with bonding separation is adopted, the isolation layer is silicon dioxide, the functional thin film layer is lithium niobate, and the functional thin film layer is obtained by bonding separation with the isolation layer after ion implantation.
Example 2 (bonding method in combination with lapping and polishing method)
1) Preparing a monocrystalline silicon substrate layer, introducing SiH gas into the monocrystalline silicon substrate layer by LPCVD under the conditions of 650 ℃ and 0.4Torr4And growing polysilicon with the thickness of 1.8 mu m.
2) Mechanically polishing the polysilicon in the step 1) to 1.4 mu m to obtain a first polysilicon layer.
3) And placing the monocrystalline silicon substrate layer and the first polycrystalline silicon layer in an oxidation furnace at the temperature of 900 ℃ for heating for 10h to form a silicon dioxide layer with the thickness of 1200nm, a monocrystalline silicon fusion layer with the thickness of 15nm and a second polycrystalline silicon layer with the thickness of 400 nm.
4) Grinding and polishing the silicon dioxide layer in the step 3) to 1000 nm.
5) Preparing a lithium niobate wafer with the same size as the monocrystalline silicon substrate, cleaning the process surface, and bonding the process surface of the cleaned lithium niobate wafer with the silicon dioxide layer prepared in the step 4) by adopting a plasma bonding method to form a bonding body; and then placing the bonding body into heating equipment to carry out heat preservation at high temperature, wherein the heat preservation process is carried out in a vacuum environment or in a protective atmosphere formed by at least one of nitrogen and inert gas, the heat preservation temperature is 400 ℃, the heat preservation time is 3 hours, and the bonding force can be improved to be more than 10 MPa.
6) And then thinning the lithium niobate single crystal film to 22 mu m by adopting a mechanical grinding mode, and then polishing to 20 mu m to obtain the lithium niobate single crystal composite film with micron-sized thickness.
It can be seen that, in example 2, a method of combining direct bonding with grinding and polishing is adopted, the isolation layer is silicon dioxide, the functional thin film layer is lithium niobate, and the functional thin film layer is directly bonded with the isolation layer and then is obtained by grinding and polishing.
Example 3 (ion implantation combined bonding separation method)
1) Preparing a monocrystalline silicon substrate layer, introducing SiH gas into the monocrystalline silicon substrate layer by LPCVD under the conditions of 650 ℃ and 0.4Torr4And growing polysilicon with the thickness of 1.8 mu m.
2) Mechanically polishing the polysilicon in the step 1) to 1.4 mu m to obtain a first polysilicon layer.
3) And placing the monocrystalline silicon substrate layer and the first polycrystalline silicon layer in an oxidation furnace at the temperature of 900 ℃ for heating for 10h to form a silicon dioxide layer with the thickness of 1200nm, a monocrystalline silicon fusion layer with the thickness of 15nm and a second polycrystalline silicon layer with the thickness of 400 nm.
4) Grinding and polishing the silicon dioxide layer in the step 3) to 1000 nm.
5) Preparing a lithium niobate wafer with the same size as the monocrystalline silicon substrate layer, and implanting helium ions (He +) into the lithium niobate wafer by using an ion implantation method, wherein the implantation energy of the helium ions is 200KeV, and the dosage is 4 multiplied by 1016ions/cm2And forming the lithium niobate wafer with a three-layer structure of a thin film layer, a separation layer and a residual material layer.
6) Bonding the thin film layer of the lithium niobate wafer after ion implantation with the silicon dioxide layer of the monocrystalline silicon substrate by adopting a plasma bonding method to form a bonded body; and then putting the bonding body into heating equipment, and preserving heat at high temperature until the residual material layer is separated from the bonding body to form the lithium niobate single crystal film. The heat preservation process is carried out in a vacuum environment or in a protective atmosphere formed by at least one of nitrogen and inert gas, the heat preservation temperature is 400 ℃, and the heat preservation time is 3 hours.
7) And polishing and thinning the lithium niobate single crystal film to 400nm to obtain the lithium niobate single crystal composite film with the nanoscale thickness.
It can be seen that, in example 3, a method of combining ion implantation with bonding separation is adopted, the isolation layer is silicon dioxide, the functional thin film layer is lithium niobate, and the functional thin film layer is obtained by bonding separation with the isolation layer after ion implantation.
Example 4 (bonding method in combination with lapping and polishing method)
1) Preparing a monocrystalline silicon substrate layer, introducing SiH gas into the monocrystalline silicon substrate layer by LPCVD under the conditions of 580 ℃ and 0.1Torr4And growing polysilicon with the thickness of 1.8 mu m.
2) Mechanically polishing the polysilicon in the step 1) to 1.4 mu m to obtain a first polysilicon layer.
3) And placing the monocrystalline silicon substrate layer and the first polycrystalline silicon layer in an oxidation furnace at the temperature of 1000 ℃ for heating for 15h to form a silicon dioxide layer with the thickness of 1200nm, a monocrystalline silicon fusion layer with the thickness of 10nm and a second polycrystalline silicon layer with the thickness of 500 nm.
4) Grinding and polishing the silicon dioxide layer in the step 3) to 1000 nm.
5) Preparing a lithium niobate wafer with the same size as the monocrystalline silicon substrate, cleaning the process surface, and bonding the process surface of the cleaned lithium niobate wafer with the silicon dioxide layer prepared in the step 4) by adopting a plasma bonding method to form a bonding body; and then placing the bonding body into heating equipment to carry out heat preservation at high temperature, wherein the heat preservation process is carried out in a vacuum environment or in a protective atmosphere formed by at least one of nitrogen and inert gas, the heat preservation temperature is 400 ℃, the heat preservation time is 3 hours, and the bonding force can be improved to be more than 10 MPa.
6) And then thinning the lithium niobate single crystal film to 22 mu m by adopting a mechanical grinding mode, and then polishing to 20 mu m to obtain the lithium niobate single crystal composite film with micron-sized thickness.
It can be seen that, in example 4, a method of combining direct bonding with grinding and polishing is adopted, the isolation layer is silicon dioxide, the functional thin film layer is lithium niobate, and the functional thin film layer is directly bonded with the isolation layer and then is obtained by grinding and polishing.
In addition, on the basis of the above embodiments, other embodiments may also be derived, such as: on the basis of each embodiment, the functional thin film layer in the embodiment is replaced by lithium tantalate, gallium arsenide, quartz or silicon, and other process parameters can be changed without changing or according to needs; that is, one skilled in the art can combine alternative materials and process parameters according to the above embodiments, and the application is not limited specifically.
The above-mentioned embodiments 1 and 3 are prepared by adopting the method of combining ion implantation with bonding separation, and the lithium niobate single crystal composite film with nano-scale thickness can be obtained; examples 2 and 4 were prepared by direct bonding in combination with lapping and polishing to obtain lithium niobate single crystal composite films with micron-sized thickness.
The present application has been described in detail with reference to specific embodiments and illustrative examples, but the description is not intended to limit the application. Those skilled in the art will appreciate that various equivalent substitutions, modifications or improvements may be made to the presently disclosed embodiments and implementations thereof without departing from the spirit and scope of the present disclosure, and these fall within the scope of the present disclosure. The protection scope of this application is subject to the appended claims.
Claims (12)
1. The composite substrate is characterized by comprising a monocrystalline silicon substrate layer (110) and a first polycrystalline silicon layer (170) from bottom to top in sequence, wherein the first polycrystalline silicon layer (170) comprises a monocrystalline silicon fusion layer (120), a second polycrystalline silicon layer (130) and a silicon dioxide layer (140);
wherein the monocrystalline silicon fused layer (120) is integrally formed with the monocrystalline silicon substrate layer (110); a fusion bulge (150) is formed on one side of the monocrystalline silicon fusion layer (120) close to the second polycrystalline silicon layer (130); the monocrystalline silicon substrate layer (110), the monocrystalline silicon fusion layer (120) and the fusion bump (150) have the same crystal orientation.
2. The composite substrate of claim 1, wherein the single crystal silicon fusion layer (120) is formed by oxidation of the first polysilicon layer (170).
3. The composite substrate according to claim 1, wherein the thickness of the monocrystalline silicon fusion layer (120) is greater than or equal to 1nm and less than or equal to 20 nm.
4. The composite substrate of claim 1, wherein the second polysilicon layer (130) has a thickness of 100nm or more and 3 μm or less.
5. The composite substrate of claim 1, wherein the fused protrusion (150) has a length of 5nm or more and 20nm or less; the width of the fusion projection (150) is more than or equal to 1nm and less than or equal to 20 nm.
6. A composite film, comprising, from bottom to top, the composite substrate according to any one of claims 1to 5 and a functional film layer (160), wherein the upper surface of the composite substrate is planarized and bonded to the functional film layer (160).
7. The composite film according to claim 6, wherein the functional film layer (160) is a lithium niobate crystal, a lithium tantalate crystal, a rubidium titanyl phosphate crystal, a potassium titanyl phosphate crystal, a silicon crystal, a germanium crystal, or a gallium arsenide crystal.
8. A radio frequency filter comprising the composite film according to any one of claims 6 to 7.
9. A method for preparing a composite film, comprising:
growing polycrystalline silicon on the monocrystalline silicon substrate layer, and flattening the polycrystalline silicon to a first target thickness to form a first polycrystalline silicon layer;
placing the monocrystalline silicon substrate layer and the first polycrystalline silicon layer in an oxidation furnace and heating to obtain a composite substrate; the composite substrate sequentially comprises a monocrystalline silicon substrate layer, a monocrystalline silicon fusion layer, a second polycrystalline silicon layer and a silicon dioxide layer from bottom to top;
planarizing the silicon dioxide layer to a second target thickness;
and preparing a functional film layer on the flattened silicon dioxide layer to obtain the composite film.
10. The method of claim 9, wherein growing polysilicon on a single-crystal silicon substrate layer and planarizing the same to a first target thickness to obtain a first polysilicon layer comprises:
introducing SiH4 gas into the monocrystalline silicon substrate layer under the conditions that the temperature is higher than or equal to 580 ℃, the temperature is lower than or equal to 650 ℃, the pressure is higher than or equal to 0.1Torr and the pressure is lower than or equal to 0.4Torr, and growing polycrystalline silicon with the thickness of 1.8 mu m;
and mechanically polishing the polysilicon to 1.4 mu m to obtain a first polysilicon layer.
11. The method for preparing a composite film according to claim 9, wherein the step of placing the single-crystal silicon substrate layer and the first polycrystalline silicon layer in an oxidation furnace and heating to obtain the composite substrate comprises:
and placing the monocrystalline silicon substrate layer and the first polycrystalline silicon layer in an oxidation furnace with the temperature of more than or equal to 800 ℃ and less than or equal to 1000 ℃ for heating for at least 10h and at most 30h to obtain the composite substrate.
12. The method of producing a composite film according to claim 9, wherein the functional thin film layer is produced on the separation layer by an ion implantation method in combination with a bonding separation method, or by a bonding method in combination with a lapping polishing method.
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