CN111740004A - Aluminum nitride-based film structure, semiconductor device and preparation method thereof - Google Patents
Aluminum nitride-based film structure, semiconductor device and preparation method thereof Download PDFInfo
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- CN111740004A CN111740004A CN202010793092.9A CN202010793092A CN111740004A CN 111740004 A CN111740004 A CN 111740004A CN 202010793092 A CN202010793092 A CN 202010793092A CN 111740004 A CN111740004 A CN 111740004A
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- PMHQVHHXPFUNSP-UHFFFAOYSA-M copper(1+);methylsulfanylmethane;bromide Chemical compound Br[Cu].CSC PMHQVHHXPFUNSP-UHFFFAOYSA-M 0.000 title claims abstract description 288
- 239000004065 semiconductor Substances 0.000 title claims abstract description 65
- 238000002360 preparation method Methods 0.000 title claims abstract description 22
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- 239000010410 layer Substances 0.000 claims abstract description 116
- 238000004544 sputter deposition Methods 0.000 claims abstract description 102
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- 238000000034 method Methods 0.000 claims description 123
- 230000008569 process Effects 0.000 claims description 98
- 239000010408 film Substances 0.000 claims description 54
- 239000010409 thin film Substances 0.000 claims description 48
- 239000013078 crystal Substances 0.000 claims description 30
- 239000007789 gas Substances 0.000 claims description 24
- 238000010438 heat treatment Methods 0.000 claims description 22
- 229910052692 Dysprosium Inorganic materials 0.000 claims description 17
- KBQHZAAAGSGFKK-UHFFFAOYSA-N dysprosium atom Chemical compound [Dy] KBQHZAAAGSGFKK-UHFFFAOYSA-N 0.000 claims description 17
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 14
- 229910045601 alloy Inorganic materials 0.000 claims description 11
- 239000000956 alloy Substances 0.000 claims description 11
- 238000004519 manufacturing process Methods 0.000 claims description 10
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims description 7
- 229910052691 Erbium Inorganic materials 0.000 claims description 7
- 229910052779 Neodymium Inorganic materials 0.000 claims description 7
- 229910052772 Samarium Inorganic materials 0.000 claims description 7
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 7
- 229910052804 chromium Inorganic materials 0.000 claims description 7
- 239000011651 chromium Substances 0.000 claims description 7
- UYAHIZSMUZPPFV-UHFFFAOYSA-N erbium Chemical compound [Er] UYAHIZSMUZPPFV-UHFFFAOYSA-N 0.000 claims description 7
- QEFYFXOXNSNQGX-UHFFFAOYSA-N neodymium atom Chemical compound [Nd] QEFYFXOXNSNQGX-UHFFFAOYSA-N 0.000 claims description 7
- KZUNJOHGWZRPMI-UHFFFAOYSA-N samarium atom Chemical compound [Sm] KZUNJOHGWZRPMI-UHFFFAOYSA-N 0.000 claims description 7
- 229910052706 scandium Inorganic materials 0.000 claims description 7
- SIXSYDAISGFNSX-UHFFFAOYSA-N scandium atom Chemical compound [Sc] SIXSYDAISGFNSX-UHFFFAOYSA-N 0.000 claims description 7
- 238000010897 surface acoustic wave method Methods 0.000 claims description 7
- 229910052719 titanium Inorganic materials 0.000 claims description 7
- 239000010936 titanium Substances 0.000 claims description 7
- 229910052689 Holmium Inorganic materials 0.000 claims description 6
- 229910052771 Terbium Inorganic materials 0.000 claims description 6
- 229910052769 Ytterbium Inorganic materials 0.000 claims description 6
- KJZYNXUDTRRSPN-UHFFFAOYSA-N holmium atom Chemical compound [Ho] KJZYNXUDTRRSPN-UHFFFAOYSA-N 0.000 claims description 6
- 238000012545 processing Methods 0.000 claims description 6
- 239000013077 target material Substances 0.000 claims description 6
- GZCRRIHWUXGPOV-UHFFFAOYSA-N terbium atom Chemical compound [Tb] GZCRRIHWUXGPOV-UHFFFAOYSA-N 0.000 claims description 6
- NAWDYIZEMPQZHO-UHFFFAOYSA-N ytterbium Chemical compound [Yb] NAWDYIZEMPQZHO-UHFFFAOYSA-N 0.000 claims description 6
- 229910052727 yttrium Inorganic materials 0.000 claims description 6
- VWQVUPCCIRVNHF-UHFFFAOYSA-N yttrium atom Chemical compound [Y] VWQVUPCCIRVNHF-UHFFFAOYSA-N 0.000 claims description 6
- 239000011261 inert gas Substances 0.000 claims description 4
- 230000007547 defect Effects 0.000 abstract description 28
- 238000000151 deposition Methods 0.000 abstract description 9
- 230000008901 benefit Effects 0.000 abstract description 5
- 230000008021 deposition Effects 0.000 abstract description 5
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- 230000008878 coupling Effects 0.000 description 8
- 238000010168 coupling process Methods 0.000 description 8
- 238000005859 coupling reaction Methods 0.000 description 8
- PIGFYZPCRLYGLF-UHFFFAOYSA-N Aluminum nitride Chemical compound [Al]#N PIGFYZPCRLYGLF-UHFFFAOYSA-N 0.000 description 7
- 229910052782 aluminium Inorganic materials 0.000 description 7
- 230000015572 biosynthetic process Effects 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 2
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 2
- IBIOTXDDKRNYMC-UHFFFAOYSA-N azanylidynedysprosium Chemical compound [Dy]#N IBIOTXDDKRNYMC-UHFFFAOYSA-N 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 238000004140 cleaning Methods 0.000 description 2
- 238000002425 crystallisation Methods 0.000 description 2
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- 239000012535 impurity Substances 0.000 description 2
- 230000006911 nucleation Effects 0.000 description 2
- 238000010899 nucleation Methods 0.000 description 2
- 238000012856 packing Methods 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 239000010703 silicon Substances 0.000 description 2
- 229910000838 Al alloy Inorganic materials 0.000 description 1
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
- AZDRQVAHHNSJOQ-UHFFFAOYSA-N alumane Chemical group [AlH3] AZDRQVAHHNSJOQ-UHFFFAOYSA-N 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 229910052729 chemical element Inorganic materials 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 239000000356 contaminant Substances 0.000 description 1
- 239000011162 core material Substances 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 238000007872 degassing Methods 0.000 description 1
- 238000000280 densification Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
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- 238000005530 etching Methods 0.000 description 1
- 239000012212 insulator Substances 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- HFGPZNIAWCZYJU-UHFFFAOYSA-N lead zirconate titanate Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[Ti+4].[Zr+4].[Pb+2] HFGPZNIAWCZYJU-UHFFFAOYSA-N 0.000 description 1
- 229910052451 lead zirconate titanate Inorganic materials 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 239000011733 molybdenum Substances 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 238000005240 physical vapour deposition Methods 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 239000002356 single layer Substances 0.000 description 1
- 238000000427 thin-film deposition Methods 0.000 description 1
- 239000011787 zinc oxide Substances 0.000 description 1
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N30/00—Piezoelectric or electrostrictive devices
- H10N30/80—Constructional details
- H10N30/85—Piezoelectric or electrostrictive active materials
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic elements; Electromechanical resonators
- H03H9/46—Filters
- H03H9/54—Filters comprising resonators of piezoelectric or electrostrictive material
- H03H9/56—Monolithic crystal filters
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic elements; Electromechanical resonators
- H03H9/46—Filters
- H03H9/64—Filters using surface acoustic waves
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N30/00—Piezoelectric or electrostrictive devices
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N30/00—Piezoelectric or electrostrictive devices
- H10N30/01—Manufacture or treatment
- H10N30/09—Forming piezoelectric or electrostrictive materials
- H10N30/093—Forming inorganic materials
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- Physics & Mathematics (AREA)
- Acoustics & Sound (AREA)
- Chemical & Material Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Surface Acoustic Wave Elements And Circuit Networks Thereof (AREA)
- Physical Vapour Deposition (AREA)
Abstract
The invention provides an aluminum nitride-based film structure, a semiconductor device and a preparation method thereof, wherein the preparation of the aluminum nitride-based film comprises the following steps: providing a semiconductor substrate with a bottom electrode layer, carrying out surface modification treatment on the bottom electrode layer to form a sputtering auxiliary surface, forming a first aluminum nitride functional layer on the sputtering auxiliary surface, and forming a second aluminum nitride functional layer on the first aluminum nitride functional layer. According to the invention, the doped aluminum nitride film is formed by preparing the first aluminum nitride functional layer and the second aluminum nitride functional layer, and the sputtering auxiliary surface is formed by performing surface modification treatment before deposition, so that the uniform and compact doped aluminum nitride film can be deposited, the defect density inside the doped aluminum nitride film can be effectively reduced, the piezoelectric property of the doped aluminum nitride film can be improved, the yield of the bulk acoustic wave filter product can be further greatly improved, and considerable economic benefits are brought to filter manufacturers.
Description
Technical Field
The invention belongs to the field of piezoelectric film and filter preparation, and particularly relates to an aluminum nitride-based film structure, a semiconductor device and a preparation method thereof.
Background
The quality and performance of the piezoelectric thin film material used as the core material of the surface acoustic wave and bulk acoustic wave filter devices determine the performance of the filter. Among them, the aluminum nitride film is the preferred material for the high frequency bulk acoustic wave filter device required by the current communication industry development because of its better piezoelectric performance, good thermal stability and compatibility with the CMOS process.
However, the piezoelectric performance of aluminum nitride is lower than that of zinc oxide and lead zirconate titanate, and the electromechanical coupling coefficient of aluminum nitride is also lower, so that the bandwidth of a filter based on the aluminum nitride film is limited, and further application of aluminum nitride is limited in some fields. Therefore, how to effectively improve the piezoelectric performance of aluminum nitride becomes a problem to be solved urgently in the industry. To improve the piezoelectric properties of the aluminum nitride film, the aluminum nitride film may be doped with chemical elements (e.g., dysprosium, erbium, neodymium, samarium, scandium, chromium, etc.), such as forming a dysprosium-doped aluminum nitride film. Although element doping of the aluminum nitride film can improve the electromechanical coupling coefficient, with the increase of the doping element content, for example, when the content of dysprosium is greater than 8%, the crystallization quality of the dysprosium-doped aluminum nitride film is deteriorated, a large number of conical dysprosium-doped aluminum nitride large crystal grains appear on the surface of the film, and a rough surface is caused by the large crystal grains, and the surface defects seriously affect the reduction of the electromechanical coupling coefficient and the quality factor of aluminum nitride.
Therefore, how to provide an aluminum nitride-based film structure, a semiconductor device and a method for manufacturing the same are necessary to solve the above problems in the prior art.
Disclosure of Invention
In view of the above-mentioned shortcomings of the prior art, the present invention aims to provide an aluminum nitride-based thin film structure, a semiconductor device and a method for manufacturing the same, which are used to solve the problems in the prior art that the defect density of the aluminum nitride-doped thin film is high, the piezoelectric performance is difficult to be continuously improved, and the performance and quality of devices such as a filter are difficult to be continuously optimized.
In order to achieve the above objects and other related objects, the present invention provides a method for preparing an aluminum nitride-based thin film structure, the method comprising the steps of:
providing a semiconductor substrate, wherein a bottom electrode layer is formed on the semiconductor substrate;
performing surface modification treatment on the bottom electrode layer to form a sputtering auxiliary surface;
forming a first aluminum nitride functional layer on the sputtering auxiliary surface by adopting a first sputtering process, wherein the first sputtering process comprises the steps of adopting a first power and a first air pressure; and
and forming a second aluminum nitride functional layer on the first aluminum nitride functional layer by adopting a second sputtering process, wherein the second aluminum nitride functional layer comprises an aluminum nitride layer doped with a preset element, the second sputtering process comprises adopting a second power and a second air pressure, the first power is smaller than the second power, the first air pressure is smaller than the second air pressure, and the first aluminum nitride functional layer and the second aluminum nitride functional layer form a doped aluminum nitride film.
Optionally, before the surface modification treatment of the bottom electrode layer, the method further comprises the steps of: and carrying out pre-control crystal orientation treatment on the bottom electrode layer so as to enable the first aluminum nitride functional layer and the second aluminum nitride functional layer to grow along a preset crystal orientation.
Optionally, the process of pre-orientation control treatment includes: and carrying out preheating treatment on the bottom electrode layer, wherein the temperature of the preheating treatment is not lower than 400 ℃, and the preset crystal orientation comprises (002) crystal face orientation.
Optionally, the process of performing surface modification treatment on the bottom electrode layer includes: and processing the surface of the bottom electrode layer under a preset bias power and a preset process gas, wherein the preset bias power is between 20 and 120W, and the preset process gas comprises an inert gas.
Optionally, after the surface modification treatment, etching away a predetermined thickness of the bottom electrode layer extending from the surface to the inside to form the sputtering auxiliary surface, where the predetermined thickness is between 2nm and 20 nm.
Optionally, the surface modification treatment further includes heating the semiconductor substrate at a temperature not lower than 300 ℃.
Optionally, the first sputtering process includes a radio frequency sputtering process or a pulsed direct current sputtering process, and the second sputtering process includes a radio frequency sputtering process or a pulsed direct current sputtering process; the first power is between 3-6kW and the first gas pressure is between 2-5 mTorr; the second power is between 6-10kW and the second gas pressure is between 3.5-10 mTorr; heating the semiconductor substrate in the first sputtering process at a temperature of between 250 and 500 ℃, and heating the semiconductor substrate in the second sputtering process at a temperature of between 250 and 500 ℃.
Optionally, a step of applying a first bias power to the semiconductor substrate during the first sputtering process, wherein the first bias power is between 50 and 300W; and/or applying a second bias power to the semiconductor substrate when the second sputtering process is carried out, wherein the second bias power is between 50 and 300W.
Optionally, the target material for performing the second sputtering process includes an alloy target, where the alloy target includes an aluminum element and the preset element, and the preset element includes at least one of dysprosium, terbium, neodymium, samarium, holmium, erbium, ytterbium, scandium, yttrium, chromium, and titanium.
Optionally, the first aluminum nitride functional layer includes at least one of the preset element doped aluminum nitride layer and an intrinsic aluminum nitride layer, where in the first aluminum nitride functional layer, the preset element doped aluminum nitride layer has a first preset element doping amount, and in the second aluminum nitride functional layer, the preset element doped aluminum nitride layer has a second preset element doping amount, and the first preset element doping amount is lower than the second preset element doping amount.
Optionally, the doping amount of the first preset element is less than 6%, and the doping amount of the second preset element is between 8% and 20%; and/or the thickness of the first aluminum nitride functional layer is between 15 and 150nm, and the thickness of the second aluminum nitride functional layer is between 500 and 1500 nm.
The invention also provides a preparation method of the semiconductor device, which comprises the step of preparing the aluminum nitride-based film structure by adopting the preparation method of the aluminum nitride-based film structure in any scheme, wherein the semiconductor device comprises a surface acoustic wave filter or a bulk acoustic wave filter.
The invention also provides an aluminum nitride-based film structure, wherein the aluminum nitride-based film structure is preferably prepared by the preparation method of the aluminum nitride-based film structure, and can be prepared by other methods, wherein the aluminum nitride-based film structure comprises the following components:
a semiconductor substrate;
a bottom electrode layer formed on the semiconductor substrate, the bottom electrode layer having a sputtering assist surface;
a first aluminum nitride functional layer formed on the sputtering auxiliary surface based on a first sputtering process using a first power and a first gas pressure; and
and the second aluminum nitride functional layer is formed on the first aluminum nitride functional layer and comprises an aluminum nitride layer doped with preset elements, and the first aluminum nitride functional layer and the second aluminum nitride functional layer form a doped aluminum nitride film, wherein the second aluminum nitride functional layer is formed on the basis of a second sputtering process adopting second power and second air pressure, the first power is smaller than the second power, and the first air pressure is smaller than the second air pressure.
Optionally, the first aluminum nitride functional layer and the second aluminum nitride functional layer are grown along a (002) crystal plane orientation.
Optionally, the target material for forming the second aluminum nitride functional layer includes an alloy target, the alloy target includes an aluminum element and a predetermined element, and the predetermined element includes at least one of dysprosium, terbium, neodymium, samarium, holmium, erbium, ytterbium, scandium, yttrium, chromium, and titanium.
Optionally, the first aluminum nitride functional layer includes at least one of the preset element doped aluminum nitride layer and an intrinsic aluminum nitride layer, where in the first aluminum nitride functional layer, the preset element doped aluminum nitride layer has a first preset element doping amount, and in the second aluminum nitride functional layer, the preset element doped aluminum nitride layer has a second preset element doping amount, and the first preset element doping amount is lower than the second preset element doping amount.
Optionally, the doping amount of the first preset element is less than 6%, and the doping amount of the second preset element is between 8% and 20%; and/or the thickness of the first aluminum nitride functional layer is between 15 and 150nm, and the thickness of the second aluminum nitride functional layer is between 500 and 1500 nm.
The invention also provides a semiconductor device comprising the aluminum nitride-based thin film structure according to any one of the above aspects, wherein the semiconductor device comprises a surface acoustic wave filter or a bulk acoustic wave filter.
As described above, according to the aluminum nitride-based thin film structure, the semiconductor device and the manufacturing method thereof of the present invention, the doped aluminum nitride thin film is formed by preparing the first aluminum nitride functional layer and the second aluminum nitride functional layer, and the sputtering auxiliary surface is formed by performing the surface modification treatment before the deposition, so that the uniform and dense doped aluminum nitride thin film can be deposited, the defect density inside the doped aluminum nitride thin film can be effectively reduced, the piezoelectric performance of the doped aluminum nitride thin film can be improved, the yield of the bulk acoustic wave filter product can be further greatly improved, and considerable economic benefits can be brought to the filter manufacturer.
Drawings
Fig. 1 is a flow chart illustrating a process for preparing an aluminum nitride-based thin film structure according to an embodiment of the present invention.
Fig. 2 is a schematic structural diagram of a semiconductor substrate provided with a bottom electrode layer in the preparation of an aluminum nitride-based thin film structure according to an embodiment of the present invention.
Fig. 3 is a schematic diagram illustrating the formation of a sputtering-assisted surface in the preparation of an aluminum nitride-based thin film structure according to an embodiment of the present invention.
Fig. 4 is a schematic diagram illustrating the formation of a first aluminum nitride functional layer in the preparation of an aluminum nitride-based thin film structure according to an embodiment of the present invention.
Fig. 5 is a schematic diagram illustrating the formation of a second aluminum nitride functional layer in the preparation of an aluminum nitride-based thin film structure provided in an embodiment of the present invention.
FIG. 6 shows the number of defects per unit area of a wafer under different process conditions according to the present invention.
FIG. 7 shows the full width at half maximum of AlN (002) orientation under different process conditions according to the present invention.
Description of the element reference numerals
100-a semiconductor substrate, 101-a bottom electrode layer, 101 a-a bottom electrode surface, 102-a sputtering auxiliary surface, 103-a first aluminum nitride functional layer, 104-a second aluminum nitride functional layer, and S1-S4.
Detailed Description
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention.
As in the detailed description of the embodiments of the present invention, the cross-sectional views illustrating the device structures are not partially enlarged in general scale for convenience of illustration, and the schematic views are only examples, which should not limit the scope of the present invention. In addition, the three-dimensional dimensions of length, width and depth should be included in the actual fabrication.
For convenience in description, spatial relational terms such as "below," "beneath," "below," "under," "over," "upper," and the like may be used herein to describe one element or feature's relationship to another element or feature as illustrated in the figures. It will be understood that these terms of spatial relationship are intended to encompass other orientations of the device in use or operation in addition to the orientation depicted in the figures. Further, when a layer is referred to as being "between" two layers, it can be the only layer between the two layers, or one or more intervening layers may also be present.
In the context of this application, a structure described as having a first feature "on" a second feature may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features are formed in between the first and second features, such that the first and second features may not be in direct contact.
It should be noted that the drawings provided in the present embodiment are only for illustrating the basic idea of the present invention, and the drawings only show the components related to the present invention rather than being drawn according to the number, shape and size of the components in actual implementation, and the type, number and proportion of the components in actual implementation may be changed arbitrarily, and the layout of the components may be more complicated.
As shown in fig. 1, the present invention provides a method for preparing an aluminum nitride-based thin film structure, comprising the following steps:
s1: providing a semiconductor substrate, wherein a bottom electrode layer is formed on the semiconductor substrate;
s2: performing surface modification treatment on the bottom electrode layer to form a sputtering auxiliary surface;
s3: forming a first aluminum nitride functional layer on the sputtering auxiliary surface by adopting a first sputtering process, wherein the first sputtering process comprises the steps of adopting a first power and a first air pressure; and
s4: and forming a second aluminum nitride functional layer on the first aluminum nitride functional layer by adopting a second sputtering process, wherein the second aluminum nitride functional layer comprises an aluminum nitride layer doped with a preset element, the second sputtering process comprises adopting a second power and a second air pressure, the first power is smaller than the second power, the first air pressure is smaller than the second air pressure, and the first aluminum nitride functional layer and the second aluminum nitride functional layer form a doped aluminum nitride film.
The method for preparing the aluminum nitride-based thin film structure according to the present invention will be described in detail with reference to the accompanying drawings. The preparation method of the aluminum nitride-based thin film structure provided by the present invention is not limited to the above sequence of steps, and may be adjusted according to common knowledge in the art.
First, as shown in S1 of fig. 1 and fig. 2, step S1 is performed to provide a semiconductor substrate 100, and a bottom electrode layer 101 is formed on the semiconductor substrate 100. The structure and the material of the semiconductor substrate 100 may be selected according to actual requirements, and may be a single-layer material layer structure or a structure formed by stacked material layers. May be a silicon substrate, and silicon-on-insulator (SOI) may also be used as the constitution of the semiconductor substrate 100. For example, in one example, the semiconductor substrate 100 may include a silicon substrate, an insulating layer, a cavity, and a cavity cap layer in order from bottom to top to fabricate a bulk acoustic wave resonator.
In addition, a bottom electrode layer 101 is formed on the semiconductor substrate 100, the bottom electrode layer 101 may be one of electrodes of a device, and in an example, the material of the bottom electrode layer 101 may be titanium, molybdenum, platinum, or aluminum, but is not limited thereto. Wherein the bottom electrode layer 101 has a bottom electrode surface 101a for preparing a device functional layer thereon, in this example, an upper surface of the bottom electrode layer 101 away from the semiconductor substrate is selected as the bottom electrode surface 101 a.
Next, as shown in S2 in fig. 1 and fig. 3, step S2 is performed to perform a surface modification treatment on the bottom electrode layer 101 to form a sputtering auxiliary surface 102. The formation of the sputtering auxiliary surface 102 facilitates the subsequent preparation of a first aluminum nitride functional layer and a second aluminum nitride functional layer on the bottom electrode layer 101 based on a sputtering process.
As an example, the process of performing the surface modification treatment on the bottom electrode layer 101 includes: the surface of the bottom electrode layer 101 (the bottom electrode surface 101 a) is processed under a preset bias power and a preset process gas, the preset bias power is between 20 and 120W, the preset process gas includes an inert gas, for example, the preset bias power may be 30W, 50W, 80W, 100W, the inert gas may be argon, after the surface modification treatment, the bottom electrode surface 101a correspondingly forms a sputtering auxiliary surface 102, which is equivalent to performing a pre-cleaning on the surface of the bottom electrode layer 101 before a subsequent deposition material layer, and can remove an oxide layer, contaminants, and impurities on the electrode surface, and also can perform a planarization treatment on the surface of the bottom electrode layer, and simultaneously eliminate surface defects and improve the smoothness of the electrode surface, that is, a smooth and defect-free surface is obtained through the above processing, so that the doping elements are precipitated, nucleated and grown up everywhere, which is beneficial to obtain more uniform and compact polycrystalline film growth in the subsequent sputtering process of the aluminum nitride (the first aluminum nitride functional layer and the second aluminum nitride functional layer), and the atomic groups (namely defects) of the gathered doping elements are difficult to appear. In addition, if a large number of defects, i.e., agglomerated atomic groups of doping elements (the concentration of doping elements is much higher than the doping concentration), occur in some regions of the aluminum nitride thin film on the wafer surface, the defect-free regions and the defective regions will exhibit different electromechanical coupling coefficients, resulting in deterioration of the uniformity of the piezoelectric performance (which is determined by the electromechanical coupling coefficients to a large extent) of the aluminum nitride thin film within the wafer, thereby greatly affecting the yield of the bulk acoustic wave filter. In addition, the surface modification treatment process, i.e., the low-bias precleaning, can obtain a smooth surface, which is very beneficial for obtaining excellent smoothness in the deposition of the aluminum nitride film; the excellent smoothness is very beneficial to the aluminum nitride film to obtain good electromechanical coupling coefficient and single (002) crystal face preferred orientation, so that the bulk acoustic wave filter can obtain higher quality factor.
In an example, after the surface modification treatment, a predetermined thickness d extending from the surface to the inside of the bottom electrode layer 101 is etched away as shown in fig. 3 to form the sputtering auxiliary surface 102, wherein the predetermined thickness is between 2nm and 20nm, and may be, for example, 2nm, 5nm, 10nm, 12nm, or 15 nm.
In another alternative example, the step of heating the semiconductor substrate 100 is further included in the process of performing the surface modification treatment, and the heating temperature is not lower than 300 ℃, for example, 400 ℃, 500 ℃ or the like. In one example, the semiconductor substrate 100 may be placed on a heating tray to heat the semiconductor substrate 100, so as to heat the bottom electrode layer 101. Based on the heating process, the wafer (the semiconductor substrate) is prevented from being cooled in the surface modification treatment process, and the wafer (the semiconductor substrate) is not beneficial to preferred orientation growth along a (002) crystal plane. The heating of the wafer to increase the temperature of the wafer not only ensures that the surface adsorbed atoms have good flow and the nucleation density of the crystal face is high, thereby being beneficial to the growth of the (002) crystal face of the thin film, but also increasing the influence of thermodynamic factors on the preferred orientation of the AlN thin film and being beneficial to the preferred orientation growth of the (002) crystal face with the close packing characteristic.
As an example, before performing the surface modification treatment on the bottom electrode layer 101 to form the sputtering auxiliary surface 102, the method further includes the steps of: and performing pre-control crystal orientation treatment on the bottom electrode layer 101 to enable the first aluminum nitride functional layer 103 and the second aluminum nitride functional layer 104 to grow along a preset crystal orientation. Based on the above processing, the growth orientations of the first aluminum nitride functional layer 103 and the second aluminum nitride functional layer 104 which follow the above processing can be controlled in advance through the processing of the bottom electrode layer 101, which is beneficial to obtaining the surface of the first aluminum nitride functional layer 103 with lower defect density and the surface of the second aluminum nitride functional layer 104 with lower defect density, thereby being beneficial to presetting the electromechanical coupling coefficient and quality factor of the element-doped aluminum nitride thin film, improving the piezoelectric performance thereof, and further improving the quality and performance of the device.
In one example, the pre-orientation control process includes performing a pre-heating process on the bottom electrode layer 101, wherein the pre-heating process is performed at a temperature not lower than 400 ℃, for example, 400 ℃, 450 ℃, 500 ℃ or the like, and the pre-heating process is performed for a heating time not less than 1 minute, for example, 2 minutes, 5 minutes, or 8 minutes. The preset crystal orientation comprises a (002) crystal face preferred orientation. The semiconductor substrate 100 may be degassed through the preheating process, and as is well known, wafer degassing is generally performed by preheating a wafer with a lamp or a heating tray before a thin film deposition process, so that the wafer reaches a predetermined temperature, and impurities and moisture on the surface of the wafer are changed into volatile gas at a high temperature and are pumped out of a chamber through a molecular pump or a cold pump provided in a preheating chamber. The temperature of the substrate is increased, that is, the semiconductor substrate 100 is subjected to the preheating treatment, which means that the energy in a sputtering system is increased, so that not only is the flow of surface adsorbed atoms good and the nucleation density of crystal planes large, which is beneficial to the growth of (002) crystal planes of the thin film, but also the influence of thermodynamic factors on the preferred orientation of the thin film is increased, which is beneficial to the growth of (002) crystal planes with close packing characteristics. In an alternative example, the preheating process may be performed by placing the semiconductor substrate 100 in a chamber, which may be a dedicated preheating chamber or a thin film sputtering process chamber, wherein a wafer tray with a heater or a lamp heating device may be provided in the chamber, or an additional heating device may be provided in the chamber.
In a further alternative example, the chamber for performing the preheating treatment may be the same chamber as the chamber for heating the semiconductor substrate 100 during the surface modification treatment described in the above example, that is, after the preheating treatment, the surface modification treatment modification is performed in the same chamber and the heating treatment during the surface modification is performed simultaneously, so as to continuously heat the semiconductor substrate. The continuous heating can keep the wafer at a higher temperature all the time, which is beneficial to the subsequent seed layer and the piezoelectric layer to avoid the preferred orientation growth along the (002) crystal face.
Next, as shown in S3 of fig. 1 and fig. 4, step S3 is performed to form a first aluminum nitride functional layer 103 on the sputtering auxiliary surface 102 by using a first sputtering process, where the first sputtering process includes using a first power and a first gas pressure, where the first aluminum nitride functional layer 103 is an undoped aluminum nitride layer or an aluminum nitride layer doped with a doping element, and may be a stacked structure composed of the above material layers. In an example, the first sputtering process comprises a radio frequency sputtering process or a pulsed direct current sputtering process, the first power is between 3-6kW, may be 3.5kW, 4kW, 5kW, and the first gas pressure is between 2-5mTorr, may be 2.5mTorr, 3mTorr, 4 mTorr. In a further example, the temperature of the wafer tray of the sputtering chamber of the aluminum nitride-based thin film (the first aluminum nitride functional layer 103) is between 250 ℃ and 500 ℃, which may be 300 ℃, 350 ℃ and 400 ℃. Is beneficial to the crystal orientation control of the film.
In a further example, the first sputtering process is performed by applying a first bias power to the semiconductor substrate 100 to facilitate controlling the stress and densification of the film. The first bias power is between 50-300W, and may be 100W, 150W, 200W, 250W. After the surface modification treatment is performed on the bottom electrode layer 101 to form the sputtering auxiliary surface 102, the first aluminum nitride functional layer 103 is formed thereon by the first sputtering process.
In an alternative example, the first aluminum nitride functional layer 103 includes at least one of the predetermined element doped aluminum nitride layer and the intrinsic aluminum nitride layer. Preferably, the first functional layer 103 of aluminum nitride is an undoped intrinsic aluminum nitride layer, which has the best smoothness and is defect-free. In addition, when the first aluminum nitride functional layer 103 is selected as the aluminum nitride layer doped with the predetermined element, the doping amount of the predetermined element is defined as a first predetermined element doping amount.
Finally, as shown in S4 in fig. 1 and fig. 4, step S4 is performed to form a second aluminum nitride functional layer 104 on the first aluminum nitride functional layer 103 by using a second sputtering process, where the second aluminum nitride functional layer 104 includes an aluminum nitride layer doped with a predetermined element, the second sputtering process includes using a second power and a second gas pressure, the first power is smaller than the second power, the first gas pressure is smaller than the second gas pressure, and the first aluminum nitride functional layer 103 and the second aluminum nitride functional layer 104 form a doped aluminum nitride film doped with a predetermined element. In an example, the second sputtering process includes a radio frequency sputtering process or a pulsed direct current sputtering process, the second power is between 6-10kW, may be 8.5kW, 9kW, 9.5kW, and the second gas pressure is between 3.5-10mTorr, may be 7.5mTorr, 8mTorr, 9 mTorr. In a further example, the wafer tray temperature of the sputtering chamber for the aluminum nitride-based thin film (the second aluminum nitride functional layer 104) is between 250 ℃ and 500 ℃, which may be 300 ℃, 350 ℃, 400 ℃. Is beneficial to the crystal orientation control of the film. The second sputtering process uses high air pressure, which is beneficial to improving the uniformity of stress in the chip, and the piezoelectric layer (the second aluminum nitride functional layer 104) with a thicker dominant film layer uses high power while using high air pressure, which is beneficial to improving the productivity of the dominant material layer.
In one example, the first sputtering process and the second sputtering process are performed in two different chambers, and a PVD tool generally used for depositing an aluminum nitride film is equipped with two or more aluminum nitride sputtering chambers, wherein the sputtering chamber 1 may be configured with a pure aluminum nitride target (or a low-doped aluminum nitride target) for depositing an aluminum nitride seed layer (a first aluminum nitride functional layer); the sputtering chamber 2 can be equipped with a highly doped aluminum nitride target for depositing a subsequent aluminum nitride piezoelectric layer (second aluminum nitride functional layer).
In addition, in the second aluminum nitride functional layer 104, the doping amount of the predetermined element is defined as a second predetermined element doping amount, wherein, when the first aluminum nitride functional layer 103 includes the aluminum nitride layer doped with the predetermined element, the first predetermined element doping amount is lower than the second predetermined element doping amount, and the doping amount refers to an atomic percentage. By way of example, the first predetermined element doping amount is less than 6%, and may be 1%, 2%, or 3%, and the second predetermined element doping amount is between 8% and 20%, and may be 10%, 12%, or 15%, and the content of the corresponding aluminum element is between 80% and 92%.
As an example, a step of applying a second bias power to the semiconductor substrate during the second sputtering process is performed, so as to facilitate controlling the stress and the density of the film layer. The second bias power is between 50-300W, and may be 60W, 80W, 100W, 150W.
After the surface modification treatment is performed on the bottom electrode layer 101 to form the sputtering auxiliary surface 102, the first aluminum nitride functional layer 103 is formed thereon by the first sputtering process, and then the second aluminum nitride functional layer is formed on the first aluminum nitride functional layer 103 by the second sputtering process, wherein the first aluminum nitride functional layer 103 with low defect density and uniform density can be obtained by using a low-power, low-pressure, bias voltage added at the same time, and a non-doped or low-predetermined element doped target. On the basis of the first aluminum nitride functional layer 103 with lower defects, a second aluminum nitride functional layer 104 with uniform density and low defect density can be grown, and the structure of the first aluminum nitride functional layer 103 can be copied to form a doped aluminum nitride thin film piezoelectric layer with uniform density and low defect density, wherein the structures of the two layers are similar.
As an example, the target material subjected to the second sputtering process includes an alloy target including an aluminum element and a predetermined element, and the predetermined element includes at least one of dysprosium, terbium, neodymium, samarium, holmium, erbium, ytterbium, scandium, yttrium, chromium, and titanium. The doping of the elements can be beneficial to improving the piezoelectric property of the aluminum nitride film, and the doping of the elements (such as the 11 elements) with the electronegativity smaller than that of aluminum and the atomic radius larger than that of aluminum in the invention can greatly improve the piezoelectric property of the aluminum nitride film. For example, dysprosium doped aluminum alloy targets or damascene targets can be made by doping or embedding dysprosium into pure aluminum for the preparation of dysprosium doped aluminum nitride films. The dysprosium is doped into the aluminum nitride to form an alloy, because the ion radius of the dysprosium is larger than that of the aluminum, the dysprosium is doped to replace partial aluminum atoms to generate lattice distortion, and the dysprosium nitride undergoes phase change, so that the elastic constant of the dysprosium nitride is softened. On the other hand, because the electronegativity of dysprosium is smaller than that of aluminum, part of dysprosium is combined with nitrogen in the form of ionic bonds after forming the alloy, so that original pure covalent bonds in aluminum nitride are changed into a mixed state in which covalent bonds and ionic bonds coexist, and the piezoelectric coefficient is enhanced. Along with the increase of the content of the doping element, if the content of dysprosium is more than 8 percent, the crystallization quality of the dysprosium-doped aluminum nitride film is deteriorated, a large number of conical dysprosium-doped aluminum nitride large crystal grains appear on the surface of the film, and a rough surface is caused by the conical dysprosium-doped aluminum nitride large crystal grains. The invention provides a method for depositing a uniform and compact doped aluminum nitride film, which can effectively reduce the defect density inside the doped aluminum nitride film and improve the piezoelectric performance of the doped aluminum nitride film, can greatly improve the yield of bulk acoustic wave filter products, and brings considerable economic benefit to filter manufacturers.
By way of example, the thickness of the first aluminum nitride functional layer 103 is between 15-150nm, such as 20nm, 30nm, 80nm, and the thickness of the second aluminum nitride functional layer 104 is between 500-1500nm, such as 600nm, 800nm, 1200 nm.
In addition, in order to further illustrate the beneficial effects of the present invention, as shown in fig. 6, the number of defects per unit area of the wafer (second aluminum nitride functional layer) under different process conditions according to the present invention is shown. In the figure, (a) shows a process of directly forming a second aluminum nitride functional layer on the bottom electrode layer (with wafer preheating at 400 ℃ or higher, which is referred to as a normal process), (b) shows a process of directly forming a second aluminum nitride functional layer after surface modification treatment of the surface of the bottom electrode layer (without forming the first aluminum nitride functional layer), (c) shows a process of forming a first aluminum nitride functional layer before forming the second aluminum nitride functional layer (without surface modification treatment) using lower power and lower gas pressure than those of the process, and (d) shows a process of surface modification treatment of the bottom electrode layer and forming the first aluminum nitride functional layer, it can be seen that the number of defects is significantly reduced in (d) the scheme of simultaneously using the surface modification treatment process and forming the first aluminum nitride functional layer. Wherein (a) results in a high defect density of about 80/cm on the surface of the doped aluminum nitride film grown on the wafer2(ii) a (b) The low bias precleaning (surface modification treatment) is added on the basis of the common aluminum nitride sputtering process, so that the defect density can be greatly reduced to 35/cm2Left and right; (c) the aluminum nitride seed layer (the first aluminum nitride functional layer) with low power and low pressure is added on the basis of the common aluminum nitride sputtering process, and the defect density can be greatly reduced to 25/cm2And (d) the effect of adding the low-bias precleaning and the low-power low-pressure aluminum nitride seed layer on the basis of (1) is best, and the defects on the unit area can be reduced to about 2-3.
As shown in fig. 7, the full width at half maximum of AlN (002) orientation under different process conditions according to the present invention is shown, in which the smaller the full width at half maximum, the better the AlN grain orientation, and the more excellent the piezoelectric properties of the AlN thin film (the lower the defect density). (a) The process of (d) is the same as that of fig. 6, and it can be seen that (d) the aspect of simultaneously using the surface modification treatment process and forming the first aluminum nitride functional layer has the minimum full width at half maximum. Wherein, (a) the (002) full width at half maximum of the doped aluminum nitride film grown by adopting a common aluminum nitride sputtering process (provided with a wafer preheating temperature of more than 400 ℃) is about 1.776 degrees (corresponding to very high defect density); (b) adding low bias voltage for pre-cleaning on the basis of a common aluminum nitride sputtering process, wherein the full width at half maximum of AlN (002) can be reduced to 1.605 degrees (corresponding to the great reduction of defect density); (c) adding a low-power low-pressure aluminum nitride seed layer on the basis of a common aluminum nitride sputtering process, wherein the full width at half maximum of AlN (002) can be reduced to 1.58 degrees (the corresponding defect density is reduced to a greater extent); (d) the effect of adding a low bias preclean and a low power low pressure aluminum nitride seed layer on the basis of (a) is best, with AlN (002) full width at half maximum being reduced to around 1.475 ° (corresponding to a very low defect density). The technical specification requirement of the industry on the half-height width of AlN (002) is less than 1.55 degrees, and if the half-height width of AlN (002) is more than 1.55 degrees, the electromechanical coupling coefficient of AlN is greatly reduced.
In addition, the invention also provides a preparation method of the semiconductor device, which comprises the step of preparing the preset element-doped aluminum nitride thin film structure by adopting the preparation method of the preset element-doped aluminum nitride thin film structure according to any one scheme, wherein the semiconductor device comprises a surface acoustic wave filter or a bulk acoustic wave filter. Of course, the bottom electrode layer serves as one of the device electrodes, and the method further comprises the step of preparing a top electrode layer on the second aluminum nitride functional layer.
In addition, as shown in fig. 5, referring to fig. 1 to 4 and fig. 6 to 7, the present invention further provides an aluminum nitride-based film structure, where the aluminum nitride-based film structure is preferably prepared by using the preparation method of the aluminum nitride-based film structure of the present invention, and of course, other methods may also be used for preparation, where the description of the material layer of the aluminum nitride-based film structure in this embodiment may refer to the description in the preparation method of the aluminum nitride-based film structure of this embodiment, and is not described herein again, and the aluminum nitride-based film structure includes:
a semiconductor substrate 100;
a bottom electrode layer 101 formed on the semiconductor substrate, the bottom electrode layer having a sputtering assist surface 102;
a first aluminum nitride functional layer 103 formed on the sputtering auxiliary surface 102 based on a first sputtering process using a first power and a first gas pressure; and
and a second aluminum nitride functional layer 104 formed on the first aluminum nitride functional layer 103, wherein the second aluminum nitride functional layer 104 includes an aluminum nitride layer doped with a predetermined element, and the first aluminum nitride functional layer 103 and the second aluminum nitride functional layer 104 form a doped aluminum nitride film, wherein the second aluminum nitride functional layer is formed based on a second sputtering process using a second power and a second gas pressure, the first power is lower than the second power, and the first gas pressure is lower than the second gas pressure.
As an example, the first aluminum nitride functional layer and the second aluminum nitride functional layer are grown along (002) crystal plane orientation.
As an example, the target material forming the second aluminum nitride functional layer 104 includes an alloy target including an aluminum element and a predetermined element, wherein the predetermined element includes at least one of dysprosium, terbium, neodymium, samarium, holmium, erbium, ytterbium, scandium, yttrium, chromium, and titanium.
Illustratively, the first aluminum nitride functional layer 103 includes at least one of the predetermined element-doped aluminum nitride layer and an intrinsic aluminum nitride layer, wherein the predetermined element-doped aluminum nitride layer in the first aluminum nitride functional layer 103 has a first predetermined element doping amount, and the predetermined element-doped aluminum nitride layer in the second aluminum nitride functional layer 104 has a second predetermined element doping amount, and the first predetermined element doping amount is lower than the second predetermined element doping amount.
By way of example, the first predetermined element doping amount is less than 6%, and the second predetermined element doping amount is between 8% and 20%.
By way of example, the thickness of the first aluminum nitride functional layer 103 is between 15-150nm, and the thickness of the second aluminum nitride functional layer 104 is between 500-1500 nm.
In addition, the invention also provides a semiconductor device, which comprises the aluminum nitride-based thin film structure according to any one of the above aspects, wherein the semiconductor device comprises a surface acoustic wave filter or a bulk acoustic wave filter. Of course, the bottom electrode layer serves as one of the device electrodes, and further includes a top electrode layer formed on the second aluminum nitride functional layer.
In summary, according to the aluminum nitride-based thin film structure, the semiconductor device and the manufacturing method thereof of the present invention, the doped aluminum nitride thin film is formed by preparing the first aluminum nitride functional layer and the second aluminum nitride functional layer, and the sputtering auxiliary surface is formed by performing the surface modification treatment before the deposition, so that the uniform and dense doped aluminum nitride thin film can be deposited, the defect density inside the doped aluminum nitride thin film can be effectively reduced, the piezoelectric performance of the doped aluminum nitride thin film can be improved, the yield of the bulk acoustic wave filter product can be further greatly improved, and considerable economic benefits can be brought to the filter manufacturer. Therefore, the invention effectively overcomes various defects in the prior art and has high industrial utilization value.
The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.
Claims (18)
1. The preparation method of the aluminum nitride-based film structure is characterized by comprising the following steps:
providing a semiconductor substrate, wherein a bottom electrode layer is formed on the semiconductor substrate;
performing surface modification treatment on the bottom electrode layer to form a sputtering auxiliary surface;
forming a first aluminum nitride functional layer on the sputtering auxiliary surface by adopting a first sputtering process, wherein the first sputtering process comprises the steps of adopting a first power and a first air pressure; and
and forming a second aluminum nitride functional layer on the first aluminum nitride functional layer by adopting a second sputtering process, wherein the second aluminum nitride functional layer comprises an aluminum nitride layer doped with a preset element, the second sputtering process comprises adopting a second power and a second air pressure, the first power is smaller than the second power, the first air pressure is smaller than the second air pressure, and the first aluminum nitride functional layer and the second aluminum nitride functional layer form a doped aluminum nitride film.
2. The method for preparing an aluminum nitride-based thin film structure according to claim 1, wherein the step of performing the surface modification treatment on the bottom electrode layer further comprises: and carrying out pre-control crystal orientation treatment on the bottom electrode layer so as to enable the first aluminum nitride functional layer and the second aluminum nitride functional layer to grow along a preset crystal orientation.
3. The method for preparing an aluminum nitride-based thin film structure according to claim 2, wherein the pre-orientation control process comprises: and carrying out preheating treatment on the bottom electrode layer, wherein the temperature of the preheating treatment is not lower than 400 ℃, and the preset crystal orientation comprises (002) crystal face orientation.
4. The method of claim 1, wherein the surface modification treatment of the bottom electrode layer comprises: and processing the surface of the bottom electrode layer under a preset bias power and a preset process gas, wherein the preset bias power is between 20 and 120W, and the preset process gas comprises an inert gas.
5. The method according to claim 4, wherein a predetermined thickness of the bottom electrode layer extending from the surface to the interior is etched after the surface modification treatment to form the sputtering auxiliary surface, wherein the predetermined thickness is between 2nm and 20 nm.
6. The method for preparing an aluminum nitride-based film structure according to claim 4, wherein the step of heating the semiconductor substrate is further included in the step of performing the surface modification treatment, and the heating temperature is not lower than 300 ℃.
7. The method according to claim 1, wherein the first sputtering process comprises a radio frequency sputtering process or a pulsed direct current sputtering process, and the second sputtering process comprises a radio frequency sputtering process or a pulsed direct current sputtering process; the first power is between 3-6kW and the first gas pressure is between 2-5 mTorr; the second power is between 6-10kW and the second gas pressure is between 3.5-10 mTorr; heating the semiconductor substrate in the first sputtering process at a temperature of between 250 and 500 ℃, and heating the semiconductor substrate in the second sputtering process at a temperature of between 250 and 500 ℃.
8. The method for preparing an aluminum nitride-based film structure according to claim 7, wherein a first bias power is further applied to the semiconductor substrate during the first sputtering process, wherein the first bias power is between 50W and 300W; and/or applying a second bias power to the semiconductor substrate when the second sputtering process is carried out, wherein the second bias power is between 50 and 300W.
9. The method according to claim 1, wherein the target material for performing the second sputtering process comprises an alloy target, the alloy target comprises an aluminum element and the predetermined element, and the predetermined element comprises at least one of dysprosium, terbium, neodymium, samarium, holmium, erbium, ytterbium, scandium, yttrium, chromium, and titanium.
10. The method for preparing an aluminum nitride-based thin film structure according to any one of claims 1 to 9, wherein the first aluminum nitride functional layer comprises at least one of the predetermined element-doped aluminum nitride layer and an intrinsic aluminum nitride layer, wherein the predetermined element-doped aluminum nitride layer has a first predetermined element doping amount in the first aluminum nitride functional layer, and the predetermined element-doped aluminum nitride layer has a second predetermined element doping amount in the second aluminum nitride functional layer, and the first predetermined element doping amount is lower than the second predetermined element doping amount.
11. The method of claim 10, wherein the first predetermined element doping amount is less than 6%, and the second predetermined element doping amount is between 8-20%; and/or the thickness of the first aluminum nitride functional layer is between 15 and 150nm, and the thickness of the second aluminum nitride functional layer is between 500 and 1500 nm.
12. A method for manufacturing a semiconductor device, characterized in that the method for manufacturing a semiconductor device comprises a step of manufacturing an aluminum nitride-based thin film structure by using the method for manufacturing an aluminum nitride-based thin film structure according to any one of claims 1 to 11, wherein the semiconductor device comprises a surface acoustic wave filter or a bulk acoustic wave filter.
13. An aluminum nitride-based film structure, comprising:
a semiconductor substrate;
a bottom electrode layer formed on the semiconductor substrate, the bottom electrode layer having a sputtering assist surface;
a first aluminum nitride functional layer formed on the sputtering auxiliary surface based on a first sputtering process using a first power and a first gas pressure; and
and the second aluminum nitride functional layer is formed on the first aluminum nitride functional layer and comprises an aluminum nitride layer doped with preset elements, and the first aluminum nitride functional layer and the second aluminum nitride functional layer form a doped aluminum nitride film, wherein the second aluminum nitride functional layer is formed on the basis of a second sputtering process adopting second power and second air pressure, the first power is smaller than the second power, and the first air pressure is smaller than the second air pressure.
14. The aluminum nitride-based thin film structure of claim 13, wherein the first and second functional layers of aluminum nitride are grown with (002) crystal plane orientation.
15. The aluminum nitride-based thin film structure of claim 13, wherein the target material forming the second aluminum nitride functional layer comprises an alloy target comprising aluminum element and a predetermined element, wherein the predetermined element comprises at least one of dysprosium, terbium, neodymium, samarium, holmium, erbium, ytterbium, scandium, yttrium, chromium, and titanium.
16. The aluminum nitride-based thin film structure of any one of claims 13 to 15, wherein the first aluminum nitride functional layer comprises at least one of the predetermined element-doped aluminum nitride layer and an intrinsic aluminum nitride layer, wherein the predetermined element-doped aluminum nitride layer in the first aluminum nitride functional layer has a first predetermined element doping amount, and the predetermined element-doped aluminum nitride layer in the second aluminum nitride functional layer has a second predetermined element doping amount, and wherein the first predetermined element doping amount is lower than the second predetermined element doping amount.
17. The aluminum nitride-based thin film structure of claim 16, wherein the first predetermined amount of doping is less than 6% and the second predetermined amount of doping is between 8-20%; and/or the thickness of the first aluminum nitride functional layer is between 15 and 150nm, and the thickness of the second aluminum nitride functional layer is between 500 and 1500 nm.
18. A semiconductor device comprising the aluminum nitride-based thin film structure according to any one of claims 13 to 17, wherein the semiconductor device comprises a surface acoustic wave filter or a bulk acoustic wave filter.
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| CN114094976B (en) * | 2022-01-24 | 2022-04-15 | 湖南大学 | A kind of aluminum nitride film and its preparation method and film bulk acoustic wave filter |
| WO2023154631A1 (en) * | 2022-02-08 | 2023-08-17 | Lam Research Corporation | Method for depositing highly doped aluminum nitride piezoelectric material |
| CN118890952A (en) * | 2024-09-29 | 2024-11-01 | 成都纤声科技有限公司 | Piezoelectric stack structure, micro-electromechanical system and method for preparing piezoelectric stack structure |
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