CN112152588B - Surface acoustic wave filter and method for processing wafer for surface acoustic wave filter - Google Patents
Surface acoustic wave filter and method for processing wafer for surface acoustic wave filter Download PDFInfo
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- CN112152588B CN112152588B CN202011023248.1A CN202011023248A CN112152588B CN 112152588 B CN112152588 B CN 112152588B CN 202011023248 A CN202011023248 A CN 202011023248A CN 112152588 B CN112152588 B CN 112152588B
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- 238000010897 surface acoustic wave method Methods 0.000 title claims abstract description 32
- 238000000034 method Methods 0.000 title claims description 33
- 238000003672 processing method Methods 0.000 claims abstract description 10
- 238000005498 polishing Methods 0.000 claims description 39
- WSMQKESQZFQMFW-UHFFFAOYSA-N 5-methyl-pyrazole-3-carboxylic acid Chemical compound CC1=CC(C(O)=O)=NN1 WSMQKESQZFQMFW-UHFFFAOYSA-N 0.000 claims description 7
- 239000013078 crystal Substances 0.000 claims description 5
- GQYHUHYESMUTHG-UHFFFAOYSA-N lithium niobate Chemical compound [Li+].[O-][Nb](=O)=O GQYHUHYESMUTHG-UHFFFAOYSA-N 0.000 claims description 3
- 239000004065 semiconductor Substances 0.000 abstract description 2
- 235000012431 wafers Nutrition 0.000 description 127
- 239000000919 ceramic Substances 0.000 description 8
- 238000004519 manufacturing process Methods 0.000 description 6
- 238000007517 polishing process Methods 0.000 description 6
- 238000001179 sorption measurement Methods 0.000 description 3
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
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- 230000004048 modification Effects 0.000 description 2
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- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- 238000006467 substitution reaction Methods 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
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- 238000005516 engineering process Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
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- 150000002739 metals Chemical class 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
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- 229910052719 titanium Inorganic materials 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
Classifications
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/25—Constructional features of resonators using surface acoustic waves
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H3/00—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators
- H03H3/007—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks
- H03H3/02—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks
Abstract
The application discloses a surface acoustic wave filter and a processing method of a wafer for the surface acoustic wave filter, and relates to the technical field of semiconductors, wherein the surface acoustic wave filter is applied to a frequency band of 2 GHz-3 GHz and comprises a wafer and an interdigital transducer; the wafer has a first face and a second face disposed opposite each other; the first face is configured to: roughness (Ra) is between 2 and 10 mu m, and the roughness is according to Ra max ‑Ra min Distributed less than or equal to 0.05; flatness of first side (TTV)<5um; the interdigital transducer is arranged on the second surface of the wafer; the interdigital transducer comprises a first interdigital transducer serving as an input end and a second interdigital transducer serving as an output end; the width of the electrode strips of the first interdigital transducer and the second interdigital transducer is between 0.2 and 0.35 mu m. The surface acoustic wave filter in the present application ensures the flatness (TTV) of the first surface in the case where the first surface of the wafer has a large roughness<5um, and reduces the output noise of the SAW filter.
Description
Technical Field
The present disclosure relates to the field of semiconductor technologies, and in particular, to a surface acoustic wave filter and a method for processing a wafer for the surface acoustic wave filter.
Background
The surface acoustic wave filter comprises a piezoelectric wafer, a first interdigital transducer and a second interdigital transducer, wherein the first interdigital transducer can generate bulk waves in the thickness direction of the piezoelectric wafer in addition to surface waves on the front surface of the piezoelectric wafer; when the bulk wave propagates to the back surface of the piezoelectric chip, the bulk wave is reflected by the back surface of the piezoelectric chip due to the difference of propagation mediums, and the second interdigital transducer receives the reflected wave, thereby outputting noise.
At present, the noise reduction method of the SAW filter is to use a piezoelectric chip with large back roughness. The traditional processing method comprises the following steps: firstly, double-sided grinding is carried out, and then single-sided thinning and single-sided polishing are carried out. However, in the double-sided lapping process, the flatness (TTV) of the back surface of the piezoelectric wafer is poor, and a thinning process with high cost is required to be added to the front surface to ensure that the flatness (TTV) of the front surface meets the requirement. In addition, in the double-sided grinding process, the piezoelectric wafer can generate a larger damaged layer, the breaking rate is higher, and in order to ensure the yield of the piezoelectric wafer, a thicker piezoelectric wafer is generally used.
Therefore, how to make the piezoelectric wafer meet the quality requirement of the back flatness (TTV <5 um) under the condition that the piezoelectric wafer is thinner and has large back roughness, so as to reduce the output noise of the surface acoustic wave filter is a problem to be solved in the art.
Disclosure of Invention
An object of the present invention is to provide a surface acoustic wave filter capable of improving output noise of the surface acoustic wave filter in the case where the wafer thickness is thin and there is a large back roughness.
It is still another object of the present application to provide a method of processing a wafer for an acoustic surface filter.
In a first aspect, an embodiment of the present application provides a surface acoustic wave filter applied to a frequency band of 2GHz to 3GHz, including:
a wafer having a first face and a second face disposed opposite each other; the first face is configured to: roughness (Ra) is between 2 and 10 mu m, and the roughness is according to Ra max -Ra min Distributed less than or equal to 0.05; flatness of first side (TTV)<5um；
An interdigital transducer disposed on the second side of the wafer; the interdigital transducer comprises a first interdigital transducer serving as an input end and a second interdigital transducer serving as an output end; the electrode bar widths of the first interdigital transducer and the second interdigital transducer are between 0.2 and 0.35 mu m. In one possible embodiment, the first face is configured as a relief structure having a ratio of maximum height (Rt) to roughness (Ra) of between 3 and 9.
In one possible embodiment, the wafer comprises a piezoelectric wafer comprising a lithium tantalate wafer, a lithium niobate wafer.
In one possible embodiment, the wafer is a 36 ° Y to 46 ° Y lithium tantalate single crystal.
In one possible embodiment, the wafer has a thickness of 150 to 250 μm.
The second surface, the embodiment of the application provides a processing method of a wafer for a surface acoustic wave filter, the wafer includes a first surface and a second surface which are oppositely arranged, and the processing method includes:
contacting the first surface of the wafer with the abrasive surface to fix the second surface;
driving the wafer to move and enabling the grinding surface to grind the first surface; the wafer moves along a sinusoidal track; after the polishing amount of the first surface reaches a predetermined value, the driving of the wafer is stopped.
In the implementation process, the second surface of the wafer is fixed, the first surface is polished by using the polishing surface, the distance between the first surface of the wafer and the polishing surface in the polishing process is ensured to be within a preset range, the roughness of the polished first surface is uniformly distributed, and the flatness (TTV) of the first surface meets the requirement. In addition, the wafer moves along the sinusoidal track, so that the wafer has a larger movement distance, and the grinding surface is sufficiently ground on the first surface.
In one possible embodiment, driving the wafer to move and cause the polishing surface to polish the first side, the wafer moving along a sinusoidal trajectory comprises:
introducing a support mechanism that moves relative to the abrasive surface, the support mechanism moving relative to the abrasive surface according to a predetermined first path;
in the moving process of the supporting mechanism, the supporting mechanism is driven to rotate;
arranging a wafer on a supporting mechanism, wherein the wafer and the supporting mechanism are eccentrically arranged; in the process that the wafer rotates along with the supporting mechanism for one circle, the motion track of the circle center of the wafer forms a sine curve on two sides of the first path.
In the implementation process, the supporting mechanism can rotate in the moving process, and because the wafers and the supporting mechanism are eccentrically arranged, the wafers are distributed in a far-near alternating mode relative to the distance between two sides of the supporting mechanism, the moving track of the circle center of the wafers forms a sine curve relative to the first path, the wafers are ensured to have a larger moving distance, and the first surface can be sufficiently ground when the grinding surface is ground.
In one possible embodiment, the distance between the center of the wafer and the center of the support mechanism is between 1 and 3cm.
In one possible embodiment, after fixing the second face before driving the wafer to move and causing the polishing surface to polish the first face, the method further comprises:
the friction force between the wafer and the polishing surface is adjusted to control the polishing rate of the polishing surface to the first surface.
In one possible embodiment, the movement of the wafer along a sinusoidal trajectory comprises:
the entire sinusoidal track is a closed loop.
In one possible embodiment, the wafer moves in a sinusoidal trajectory:
the entire sinusoidal track is rectilinear.
In one possible embodiment, after the polishing amount of the first face reaches a predetermined value and the driving of the wafer is stopped, the method further comprises:
and polishing the second surface.
In the implementation process, the grinding amount of the first surface reaches a preset value, and the ground first surface meets the quality requirement that TTV is less than 5um; the first surface is fixed on the polishing mechanism through adsorption, and the second surface is polished.
Compared with the prior art, the beneficial effect of this application:
1. in the surface acoustic wave filter, the first surface of the wafer is configured to have a large roughness (2-10 μm) and the roughness is uniformly distributed, the maximum roughness value Ra max And a minimum roughness value Ra min Less than 0.05. In the case where the first side of the wafer has a large roughness, the flatness (TTV) of the first side is ensured<5um, thereby reducing the output noise of the SAW filter.
2. In the processing method of the wafer, the first surface is polished on one side by utilizing the polishing surface, so that the roughness distribution of the polished first surface is uniform, and the flatness (TTV) of the first surface meets the requirement. After the flatness of the first surface meets the quality requirement, the first surface can be directly fixed on the polishing mechanism through adsorption, and the second surface can be directly polished without additional thinning treatment, so that the production cost is reduced, and the polishing machine is more suitable for mass production popularization.
3. The roughness of the first surface and the second surface can be achieved under the condition of low removal amount of the wafer, so that the number of wafers produced by a single crystal can be increased, and the productivity of the wafers can be improved.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered limiting the scope, and that other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic structural view of a surface acoustic wave filter according to an embodiment of the present application;
fig. 2 is a schematic diagram of a structure of a wafer in a surface acoustic wave filter according to an embodiment of the present application.
Fig. 3 is a flowchart of a processing method of a wafer for a surface acoustic wave filter according to an embodiment of the present application;
FIG. 4 is a schematic view of a structure of a stationary wafer according to an embodiment of the present application;
FIG. 5 is a schematic view of a structure of a stationary wafer according to an embodiment of the present application;
FIG. 6 is a schematic diagram of a motion profile of a wafer according to an embodiment of the present application;
fig. 7 is a flowchart showing a processing method of a wafer for a surface acoustic wave filter according to an embodiment of the present application.
Illustration of:
100 wafers; 110 a first side; a 120 second side; 200 ceramic discs; 210 weight increasing disc; 300 a support mechanism; 400 lower disc surface of the grinder; 500 interdigital transducers; 510 a first interdigital transducer; 520 second interdigital transducer.
Detailed Description
The following detailed description of specific embodiments of the present application is provided merely to illustrate the application and not to limit the application in any way.
In the description of the present application, it should be noted that, unless explicitly specified and limited otherwise, the term "connected" should be construed broadly, and for example, it may be a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the terms in this application will be understood by those of ordinary skill in the art as the case may be.
In the description of the present application, it should be noted that the terms "first" and "second," etc. are used merely to distinguish between descriptions and should not be construed as indicating or implying relative importance.
According to one aspect of the present application, a surface acoustic wave filter is provided. The surface acoustic wave filter is applied to the frequency range of 2 GHz-3 GHz. Referring to fig. 1 and 2, the saw filter includes a wafer 100 and an interdigital transducer 500. The wafer 100 has a first side 110 and a second side 120 disposed opposite each other; the first face 110 is configured to: roughness (Ra) is between 2 and 10 mu m, and the roughness is according to Ra max -Ra min Distributed less than or equal to 0.05; first, theFlatness of one side 110 (TTV)<5um. The interdigital transducer 500 is disposed on the second face 120 of the wafer 100; the interdigital transducer 500 includes a first interdigital transducer 510 as an input and a second interdigital transducer 520 as an output; the width of the electrode strips of the first interdigital transducer 510 and the second interdigital transducer 520 is 0.2 to 0.35 μm.
Preferably, the first surface 110 of the wafer 100 is configured as a concave-convex structure, and the ratio of the maximum height (Rt) of the concave-convex structure to the roughness (Ra) is between 3 and 9. If the ratio of the maximum height (Rt) to roughness (Ra) of the relief structure is greater than 9, the polished first surface 110 has a deeper loss layer, and the strength of the wafer 100 is reduced, which may have a greater risk of breakage during subsequent processing. If the ratio of the maximum height (Rt) to the roughness (Ra) of the concave-convex structure is less than 3, the first surface 110 needs to be polished by using an abrasive having a very uniform particle size distribution, but the abrasive is expensive and is not suitable for mass production.
Preferably, the wafer 100 comprises a piezoelectric wafer having piezoelectric properties such as lithium tantalate, lithium niobate, and the like. Specifically, the wafer 100 is a 36 ° Y to 46 ° Y lithium tantalate single crystal.
Preferably, the thickness of the wafer 100 is between 150 and 300 μm. Preferably, the wafer 100 has a thickness of 150 to 250 μm. The roughness (Ra) of the first surface 110 is preferably 3 μm, 5 μm, 8 μm, or 9 μm; the roughness of the second surface 120 is between 0.2 and 0.5nm.
Preferably, the thickness of the electrode bars of the first interdigital transducer 510 and the second interdigital transducer 520 is 200 to 300nm. The electrode strip is made of metals such as aluminum, copper, nickel, titanium, platinum, silver and the like.
As can be seen from the above, in the surface acoustic wave filter, the first surface 110 of the wafer 100 is configured to have a large roughness, and the roughness is uniformly distributed. In the case where the first face 110 of the wafer 100 has a large roughness, the flatness (TTV) of the first face 110 is ensured to be <5um, and the quality of the surface acoustic wave filter is improved. The first interdigital transducer 510 generates a surface wave on the second surface 120 of the wafer 100, and generates a bulk wave in the thickness direction of the wafer 100, and when the bulk wave propagates from the second surface 120 to the first surface 110, since the first surface 110 has a large roughness, scattering of the bulk wave can be improved, and output noise of the surface acoustic wave filter can be reduced.
According to another aspect of the present application, a method of processing a wafer for a surface acoustic wave filter is provided. Referring to fig. 3, a wafer 100 includes oppositely disposed first and second sides 110, 120, and the processing method includes the steps of:
s1, making the first surface 110 of the wafer 100 contact with the grinding surface, and fixing the second surface 120;
s2, driving the wafer 100 to move and enabling the grinding surface to grind the first surface 110; the wafer 100 moves along a sinusoidal trajectory; after the polishing amount of the first surface 110 reaches a predetermined value, the driving of the wafer 100 is stopped.
Specifically, the wafer 100 is a piezoelectric wafer, including a lithium tantalate wafer. The thickness of the wafer 100 is less than 250 μm. The roughness of the first surface 110 is 2-10 μm; the removal amount of the first face 110 during the polishing of the first face 110 is 5 to 10 μm.
In the above implementation process, the second surface 120 of the wafer 100 is fixed, and the first surface 110 is polished on one side by using the polishing surface, so that the distance between the first surface 110 and the polishing surface of the wafer is ensured to be within a predetermined range during the polishing process, and the polishing surface is uniformly polished on the first surface 110; roughness of the polished first face 110 is in accordance with Ra max -Ra min And is uniformly distributed less than or equal to 0.05, and the flatness (TTV) of the first face 110 is less than 5 μm. In addition, the wafer 100 moves along a sinusoidal track, so that the wafer 100 has a larger movement distance, and the grinding surface is sufficiently ground on the first surface 110.
In one embodiment, in step S2, the ratio of the maximum height (Rt) of the first face 110 to the roughness (Ra) is between 3 and 9. If the ratio of maximum height (Rt) to roughness (Ra) is greater than 9, the polished first side 110 has a deeper sacrificial layer, and the strength of the wafer 100 is reduced, which may be at a greater risk of breakage during subsequent processing. If the ratio of the maximum height (Rt) to the roughness (Ra) is less than 3, the first surface 110 is polished by using an abrasive having a very uniform particle size distribution, but the abrasive is expensive and is not suitable for mass production.
In one embodiment, referring to fig. 4, in step S1, contacting the first side 110 of the wafer 100 with the abrasive surface, securing the second side 120 includes:
introducing a ceramic disc 200 for fixing the wafer 100;
the second face 120 is secured to the ceramic disk 200 and the first face 110 is in contact with the abrasive surface. The second face 120 is fixed to the ceramic disc 200, so that the second face 120 is prevented from being polished and a damaged layer is prevented from being generated during the subsequent polishing process of the first face 110.
It should be noted that the ceramic disc 200 is only exemplary, and the present application does not specifically limit the ceramic disc 200, and any structure capable of fixing the wafer 100 falls within the scope of protection of the present application.
In one embodiment, in step S2, driving the wafer 100 to move and cause the polishing surface to polish the first surface 110, the wafer 100 moving along a sinusoidal track includes:
a support mechanism 300 that introduces motion relative to the abrasive surface; the support mechanism 300 moves relative to the abrasive surface according to a predetermined first path; the first path is the motion track of the circle center of the supporting mechanism 300;
during the movement of the supporting mechanism 300, the supporting mechanism 300 is driven to rotate;
disposing the wafer 100 on the support mechanism 300 such that the wafer 100 is disposed eccentrically to the support mechanism 300; during the rotation of the wafer 100 along with the supporting mechanism 300, the motion track of the center of the wafer 100 forms a sine curve on two sides of the first path.
Referring to fig. 5 and 6, the ceramic disc 200 to which the wafer 100 is fixed is placed on the supporting mechanism 300, and the first face 110 of the wafer 100 is in contact with the abrasive face; the wafer 100 and the supporting mechanism 300 are eccentrically arranged, and the center of the wafer 100 and the center of the supporting mechanism 300 are at a preset distance, that is, the edge of the wafer 100 at the same side and the edge of the supporting mechanism 300 comprise two distances, namely a long distance L1 and a short distance L2.
Preferably, the supporting mechanism 300 performs a circular motion, and the supporting mechanism 300 rotates during the circular motion; the entire sinusoidal path of the center of the wafer 100 is in the shape of a closed loop.
Referring to fig. 6, the support mechanism 300 is capable of rotating during movement, and since the wafer 100 is eccentrically disposed with respect to the support mechanism 300, the edge of the wafer 100 and the edge of the support mechanism 300 include a long distance L1 and a short distance L2. During the movement of the supporting mechanism 300 on the lower disc surface 400 of the grinder and the rotation thereof, the circle centers of the wafers 100 are alternately arranged on both sides of the first path, that is, the distance between the wafers 100 and the outer circumference of the lower disc surface 400 of the grinder is alternately arranged at a distance and a near distance, that is, the distance L1 and the near distance L2 are alternately arranged, the whole movement track of the circle center of the wafers 100 forms a sine curve, the wafers 100 are ensured to have a larger movement distance, and the grinding surface can sufficiently grind the first surface 110.
Preferably, the supporting mechanism 300 moves linearly, and the supporting mechanism 300 rotates during the linear movement, and the entire sinusoidal track of the center of the wafer 100 is linear.
Preferably, the distance between the center of the wafer 100 and the center of the supporting mechanism 300 is 1-3 cm.
Specifically, the support mechanism 300 includes a star wheel provided with a clamping groove for fixing the wafer 100, and the clamping groove is eccentrically disposed with respect to the star wheel.
It should be noted that the support mechanism 300 including the star wheel is only exemplary, and the structure of the support mechanism 300 is not specifically limited in this application, and any structure that can be eccentrically disposed with respect to the wafer 100 and move with respect to the abrasive surface falls within the scope of protection of this application.
In one embodiment, after fixing the second face 120 before driving the wafer 100 to move and polishing the first face 110, the method further includes:
the friction between the wafer 100 and the polishing surface is adjusted to control the polishing rate of the polishing surface to the first surface 110.
Specifically, referring to fig. 4, the grinding rate of the grinding surface facing the first face 110 is adjusted by providing a weighting disc 210 on the ceramic disc 200 to adjust the frictional force between the grinding surface and the wafer 100. The weight plate 210 is used to provide friction force for the wafer 100, so that the first surface of the wafer 100 is uniformly subjected to friction force, the breaking rate of the wafer 100 is reduced, and the yield is improved.
When the polishing speed of the first surface 110 increases, the removal amount of the polishing surface to the first surface 110 can be increased in unit time, so that the influence of the external structure on the polishing process of the first surface is reduced, and the uniform roughness distribution of the first surface 110 is further ensured.
In one embodiment, referring to fig. 7, after the polishing amount of the first surface 110 reaches a predetermined value and the driving of the wafer 100 is stopped, the method further includes:
and S3, polishing the second surface 120.
Specifically, first, the second surface 120 is brought into contact with the polishing surface, and the first surface 110 is fixed. The grinding amount of the first surface 110 reaches a preset value, and the ground first surface 110 meets the quality requirement that TTV is less than 5um; the first surface 110 can be directly fixed on the polishing mechanism through adsorption, and the flatness of the second surface 120 meets the requirements, so that the second surface 120 is not required to be subjected to additional thinning treatment, the production cost is reduced, and the polishing device is more suitable for mass production popularization.
Then, the second surface 120 is polished by the polishing surface to make the roughness of the second surface 120 reach a preset value. Preferably, the roughness of the second surface 120 is between 0.2 nm and 0.5nm; in the polishing process, the removal amount of the second face 120 is 5 to 15um.
Processing the wafer 100 by the method, wherein only the first surface 110 is required to be polished in the process of polishing the first surface 110, and the second surface 100 has no damaged layer; in the polishing process of the second face 120, since the first face 110 satisfies the requirements, only the second face 120 needs to be polished. The method can effectively reduce the removal amount of the wafer 100, can reach the roughness of the first surface 110 and the second surface 120 under the condition of low removal amount, can increase the number of wafers 100 produced by a single crystal, and can improve the productivity of the wafers 100.
When a wafer with the roughness of the first surface 110 of 3 μm is processed by the above method, the first surface 110 is divided into three areas of upper, middle and lower, and the roughness of the three areas is tested respectively; the difference in roughness of the upper, middle and lower three areas measured was only 0.01 μm; the flatness of the first side 110 is 1.46um, which meets the expected value, i.e., the first side of the wafer 100 obtained by the above method meets the requirements.
The foregoing is merely a preferred embodiment of the present application, and it should be noted that modifications and substitutions can be made by those skilled in the art without departing from the technical principles of the present application, and these modifications and substitutions should also be considered as being within the scope of the present application.
Claims (11)
1. A surface acoustic wave filter applied to a frequency band of 2GHz to 3GHz, comprising:
a wafer with a thickness of 150-250 μm and a first surface and a second surface which are oppositely arranged; the first face is configured to: roughness (Ra) of 3-10 mu m, and the roughness is according to Ra max -Ra min Distributed less than or equal to 0.05; flatness of the first side (TTV)<5um；
An interdigital transducer disposed on a second side of the wafer; the interdigital transducer comprises a first interdigital transducer serving as an input end and a second interdigital transducer serving as an output end; the widths of electrode strips of the first interdigital transducer and the second interdigital transducer are between 0.2 and 0.35 mu m.
2. The surface acoustic wave filter according to claim 1, wherein the first face is configured as a concave-convex structure, and a ratio of a maximum height (Rt) to roughness (Ra) of the concave-convex structure is 3 to 9.
3. The saw filter of claim 1, wherein the wafer comprises a piezoelectric wafer comprising a lithium tantalate wafer, a lithium niobate wafer.
4. A surface acoustic wave filter according to claim 3, wherein the wafer is a 36 ° Y-46 ° Y lithium tantalate single crystal.
5. A processing method of a wafer for a surface acoustic wave filter, the surface acoustic wave filter having a surface acoustic waveThe wave filter is applied to a frequency band of 2 GHz-3 GHz, the thickness of the wafer is 150-250 mu m, and the wafer is provided with a first surface and a second surface which are oppositely arranged; the first face is configured to: roughness (Ra) of 3-10 mu m, and the roughness is according to Ra max -Ra min Distributed less than or equal to 0.05; flatness of the first side (TTV)<5um, characterized in that the processing method comprises:
contacting the first side of the wafer with an abrasive side to secure the second side;
driving the wafer to move and enabling the grinding surface to grind the first surface; the wafer moves along a sinusoidal track; and stopping driving the wafer after the grinding amount of the first surface reaches a preset value.
6. The method of claim 5, wherein the driving the wafer to move and the polishing surface to polish the first surface, the wafer moving along a sinusoidal trajectory comprises:
introducing a support mechanism that moves relative to the abrasive surface, the support mechanism moving relative to the abrasive surface according to a predetermined first path;
in the moving process of the supporting mechanism, the supporting mechanism is driven to rotate;
arranging the wafer on the supporting mechanism, wherein the wafer and the supporting mechanism are eccentrically arranged; and in the process that the wafer rotates along with the supporting mechanism for one circle, the motion track of the circle center of the wafer forms a sine curve at two sides of the first path.
7. The method of claim 6, wherein the distance between the center of the wafer and the center of the support mechanism is between 1 cm and 3cm.
8. The method of processing a wafer according to any one of claims 5 to 7, wherein after the fixing of the second face before the driving of the wafer to move and the polishing of the polishing face to the first face, further comprises:
and adjusting the friction force between the wafer and the grinding surface to control the grinding speed of the grinding surface to the first surface.
9. The method of processing a wafer of claim 8, wherein the wafer moving along a sinusoidal trajectory comprises:
the whole sinusoidal track is closed annular.
10. The method of processing a wafer of claim 8, wherein the wafer moving along a sinusoidal trajectory comprises:
the entire sinusoidal track is rectilinear.
11. The method for processing a wafer according to claim 8, further comprising, after the polishing amount of the first surface reaches a predetermined value and driving of the wafer is stopped:
and polishing the second surface.
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Citations (16)
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