A tuning fork chip micro-nano processing method using laser, and tuning fork chip

Abstract

The present invention provides a tuning fork wafer micro-nano processing method using laser, and a tuning fork wafer, the method comprising: providing a wafer; using a laser to write on the wafer once to form a pattern of the tuning fork wafer distributed at intervals; wet etching the wafer to form the wafer with a hollow pattern; coating the surface of the wafer with a metal layer, etching the metal layer with a second laser to form an electrode pattern of the tuning fork wafer; cutting the wafer with a third laser, and obtaining the tuning fork wafer after separation. The method using laser micro-nano processing of the present invention is a maskless process, with a simple process flow and low production cost. The tuning fork wafer prepared by the method has high size and electrode precision and small frequency error.

Description

Technical Field

[0001] The invention relates to the technical field of quartz crystal processing, and in particular to a tuning fork wafer micro-nano processing method using laser and a tuning fork wafer. Background Art

[0002] There are two ways to manufacture tuning fork wafers. Method 1: a strip wafer is cut into tuning fork wafers by wire cutting, with a cutting size error of 100 to 300 microns. The tuning fork resonance wafer is manufactured by silver plating, with a frequency error of 2KHz, and then mechanical grinding is used to achieve frequency consistency.

[0003] Method 2: Using quartz wafer lithography technology, exposure and development pattern transfer wet etching method to manufacture tuning fork chips and electrodes. The chip size error can reach ±3 microns, with many process flows, which is suitable for the manufacture of miniature tuning fork resonators.

[0004] The above-mentioned method 1 has poor manufacturing precision and many processes, and requires a lot of manpower to manufacture large-size quartz resonant chips; the second method is a semiconductor photolithography process with high precision, which is suitable for miniature tuning fork resonant chips, but the equipment investment cost is high. Summary of the invention

[0005] Based on the problems existing in the above-mentioned prior art, the present invention aims to provide a tuning fork chip micro-nano processing method and tuning fork chip using laser, which utilizes multiple laser micro-nano processing, a maskless process throughout the process, a simple process, and low cost. The tuning fork chip has high size and electrode accuracy and small frequency error.

[0006] The present invention provides a tuning fork wafer micro-nano processing method using laser, the method comprising:

[0007] providing a wafer;

[0008] Using a single laser engraving process to form a pattern of tuning fork wafers distributed at intervals on the wafer;

[0009] Performing wet etching on the wafer to form the wafer having a hollow pattern;

[0010] Plating a metal layer on the surface of the wafer, and etching the metal layer by secondary laser to form an electrode pattern of the tuning fork wafer;

[0011] The wafer is cut by laser three times, and the tuning fork wafer is obtained after separation.

[0012] In one embodiment of the present invention, the power of the primary laser is smaller than the power of the secondary laser, and the power of the secondary laser is smaller than the power of the tertiary laser.

[0013] In one embodiment of the present invention, the step of forming a pattern of the tuning fork wafers distributed at intervals on the wafer by laser writing once comprises:

[0014] The laser engraving of the wafer once forms the outer contour of the tuning fork wafer, and correspondingly forms a closed laser engraving area on the wafer; wherein the laser engraving area is interlocked with the tuning fork wafers that are distributed at intervals.

[0015] In one embodiment of the present invention, the step of wet etching the wafer to form the wafer having a hollow pattern includes:

[0016] The wafer is immersed in an etching solution for wet etching to remove the wafer portion located in the laser writing area, thereby correspondingly forming a hollow pattern of the wafer.

[0017] In one embodiment of the present invention, the spot coverage range of the primary laser is 0.5-5 microns, and the hole center distance between adjacent spots is 1-10 microns.

[0018] In one embodiment of the present invention, after the first laser etching and before the wet etching, the method further comprises: using a hydrofluoric acid solution to repair the surface of the wafer after the first laser etching.

[0019] In one embodiment of the present invention, the laser pulse width of the secondary laser is picoseconds or femtoseconds.

[0020] In one embodiment of the present invention, the wavelengths of the three laser beams are selected from 1064 nm, 532 nm or ultraviolet band.

[0021] In one embodiment of the present invention, the wet etching uses an acid solution, an alkaline solution or a buffered oxide etching solution.

[0022] The present invention also provides a tuning fork wafer, which is prepared by using the tuning fork wafer micro-nano processing method using laser as described in any of the above embodiments.

[0023] Beneficial effects:

[0024] The present invention provides a tuning fork wafer micro-nano processing method using laser, and a tuning fork wafer, the method comprising: providing a wafer; using a laser to write on the wafer once to form a pattern of the tuning fork wafer distributed at intervals; wet etching the wafer to form the wafer with a hollow pattern; coating the surface of the wafer with a metal layer, etching the metal layer with a second laser to form an electrode pattern of the tuning fork wafer; cutting the wafer with a third laser, and obtaining the tuning fork wafer after separation. The method using laser micro-nano processing of the present invention is a maskless process, with a simple process flow and low production cost. The tuning fork wafer prepared by the method has high size and electrode precision and small frequency error. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 1. It is a schematic flow chart of the laser micro-nano processing method according to an embodiment of the present invention;

[0027] Figure 2 This is a schematic diagram of a laser writing and wet etching process according to an embodiment of the present invention;

[0028] Figure 3 is a comparison diagram of a vacuum-plated electrode and a secondary laser-etched electrode according to an embodiment of the present invention;

[0029] Figure 4 is a schematic diagram of various dimensions of a tuning fork wafer according to an embodiment of the present invention;

[0030] Figure 5 1. is a comparison diagram of the dimensions of conventional wire cutting processing and laser micro-nano processing of an embodiment of the present invention;

[0031] Figure 6 It is a comparison diagram of the frequency distribution of traditional wire cutting processing and laser micro-nano processing in an embodiment of the present invention. DETAILED DESCRIPTION

[0032] The following descriptions of the embodiments are made with reference to the attached drawings to illustrate specific embodiments of the present invention. The directional terms mentioned in the present invention, such as [upper], [lower], [front], [back], [left], [right], [inner], [outer], [side], etc., are only with reference to the directions of the attached drawings. Therefore, the directional terms used are used to illustrate and understand the present invention, but are not used to limit the present invention.

[0033] In the prior art, the main process flow of the traditional wire cutting tuning fork wafer processing method includes: starting from the processing of the raw material of the crystal rod, sequentially carrying out the steps of crystal rod directional pasting, primary cutting, secondary cutting, rough grinding, fine grinding, sticking, grinding, wire cutting, size classification, size trimming, sticking glue dissolving, appearance selection, silver molding, vacuum coating electrode, appearance inspection, etc. It can be seen that the traditional wire cutting process is complicated, and the size of the tuning fork wafer is cut / grinded and trimmed many times, resulting in poor processing accuracy and low product yield.

[0034] The present invention provides a tuning fork wafer micro-nano processing method using laser, the method comprising:

[0035] providing a wafer;

[0036] Using a single laser engraving process to form a pattern of tuning fork wafers distributed at intervals on the wafer;

[0037] Performing wet etching on the wafer to form the wafer having a hollow pattern;

[0038] Plating a metal layer on the surface of the wafer, and etching the metal layer by secondary laser to form an electrode pattern of the tuning fork wafer;

[0039] The wafer is cut by laser three times, and the tuning fork wafer is obtained after separation.

[0040] Specifically, Figure 1 The preparation process flow chart of the tuning fork wafer shown in the figure first provides a wafer of suitable size, places the wafer in the laser processing equipment station, and uses a primary laser to write the pattern of tuning fork wafers distributed at intervals on the surface of the wafer. The tuning fork wafers are distributed in a matrix, and the spacing distance between adjacent tuning fork wafers can be adaptively adjusted according to the needs. The surface laser writing of the wafer can be single-sided writing, or it can be written on the opposite front and back sides of the wafer, which is conducive to the efficiency of subsequent wet etching. The wafer after writing is placed in an etching solution for wet etching treatment, and the unnecessary wafer parts are removed to form a hollow pattern. At this time, the wafer presents the outer contour morphology of the tuning fork wafer distributed at intervals. The tuning fork wafer includes a vibration part and a base structure. Next, a metal layer is plated on the surface of the wafer, and then the wafer is placed in the laser processing equipment station, and the electrode pattern of the tuning fork wafer is etched on the surface of the wafer using a secondary laser, such as the excitation electrode on the vibration part of the tuning fork wafer, the connection electrode on the base, and other electrode traces. Finally, the wafer is cut by laser three times to separate a plurality of independent tuning fork wafers from the wafer for subsequent processing.

[0041] Compared with the prior art, the tuning fork chip micro-nano processing method using laser provided by the present invention does not require the use of a mask process in the entire process from wafer to tuning fork chip product, thereby saving the cost of using the mask and simplifying the process; at the same time, it ensures the advantages of high dimensional accuracy and small frequency error of the tuning fork chip.

[0042] In one embodiment of the present invention, the power of the primary laser is smaller than the power of the secondary laser, and the power of the secondary laser is smaller than the power of the tertiary laser.

[0043] Specifically, in the laser micro-nano processing method, the present invention utilizes multiple laser processing technology to completely replace the wire cutting technology, photolithography process, and mask process in the prior art. Multiple lasers are distributed in the front and back sections of the processing method, and are used in conjunction with each other and in association. The power of the primary laser, the secondary laser, and the tertiary laser are set to be different to meet the processing requirements of different process sections. The primary laser is used for laser engraving of the wafer, and the properties of the wafer material are changed by laser induction to form a patterned mark. The secondary laser is used for electrode etching of the wafer after coating, and the metal layer on the surface of the wafer is ablated by laser to form an electrode pattern designed by the tuning fork wafer. The tertiary laser is used for cutting the wafer after electrode patterning, and the connection between the tuning fork wafer and the other parts of the wafer is cut by laser to separate the tuning fork wafer. It can be seen from this that the power of the primary laser is less than the power of the secondary laser, and the power of the secondary laser is less than the power of the tertiary laser. The above-mentioned multiple laser processing can use the same laser processing equipment or multiple laser processing equipment to achieve the output requirements of different laser powers.

[0044] In one embodiment of the present invention, the spot coverage of the primary laser is 0.5-5 microns, and the hole center distance between adjacent spots is 1-10 microns. The laser pulse width of the secondary laser is picosecond or femtosecond; the wavelength of the tertiary laser is selected from 1064nm, 532nm or ultraviolet band.

[0045] Specifically, Figure 2 As shown, the scoring line written by the primary laser is formed by splicing multiple laser spots. The spot shape of the primary laser can be circular, quasi-circular or polygonal. The coverage range of the spot is selected to be 0.5-5 microns. The center distance between the holes of adjacent spots is 1-10 microns. The above parameters can be adaptively adjusted according to the size processing accuracy of the tuning fork wafer. The laser pulse width of the primary laser, the secondary laser and / or the tertiary laser is 10 -12 Seconds or 10 -15 The laser wavelength is selected from 1064nm, 532nm or ultraviolet band. The laser processing time is short and the precision is high. At the same time, the output power of the laser is stable and reliable, which is conducive to the consistency of the size and frequency of the tuning fork chip.

[0046] like Figure 3As shown, the left picture is a tuning fork wafer electrode pattern prepared by vacuum plating process, and the right picture is a tuning fork wafer electrode pattern prepared by secondary laser etching of the present invention. First, in the vacuum coating process, a mask is used to block and prepare the corresponding electrode pattern, but due to the mask accuracy problem and the positioning error problem between the tuning fork wafer and the mask, the electrode coating on the surface of the tuning fork wafer will diffuse, resulting in irregular electrode size and large dispersion (the discrete degree of the measurement sample) and other undesirable phenomena. In contrast, the present invention utilizes secondary laser etching of the metal layer on the wafer to eliminate excess metal coating outside the electrode pattern; the outer contour and size of the tuning fork wafer electrode pattern after secondary laser etching are more regular, and there is no need to use a mask process, so the process flow is simpler and more efficient, and it requires less equipment investment, has high efficiency, and has the advantages of high yield.

[0047] In one embodiment of the present invention, the step of forming a pattern of the tuning fork wafers distributed at intervals on the wafer by laser writing once comprises:

[0048] The laser engraving of the wafer once forms the outer contour of the tuning fork wafer, and correspondingly forms a closed laser engraving area on the wafer; wherein the laser engraving area is interlocked with the tuning fork wafers that are distributed at intervals.

[0049] like Figure 2 As shown, the laser engraving of the wafer once forms the outer contour line of the tuning fork wafer. It can be seen from the figure that there are multiple tuning fork wafers arranged in an array with a repeating pattern. Specifically, a longitudinal notch is engraved on the outer side of the first tuning fork wafer in any row, a longitudinal notch is engraved on the outer side of the last tuning fork wafer in a row, a transverse notch is engraved on the upper end of the tuning fork wafer in this row, and the longitudinal notches on both sides are connected to the transverse notch on the upper end, and the outer contour of the same tuning fork wafer is repeatedly engraved in sequence to finally form a closed laser engraving area, that is, the laser engraving area and the tuning fork wafers distributed at intervals are interlocked with each other.

[0050] The longitudinal direction is consistent with the long end direction of the tuning fork wafer, and the transverse direction is consistent with the short end direction of the tuning fork wafer. The length of the longitudinal notch is greater than the total length of a single tuning fork wafer, and the length of the transverse notch is greater than the sum of the total widths of the tuning fork wafers in this row. The distances between the longitudinal notch and the transverse notch and the tuning fork wafer are adaptively set.

[0051] Next, the step of wet etching the wafer to form the wafer with a hollow pattern includes:

[0052] The wafer is immersed in an etching solution for wet etching to remove the wafer portion located in the laser writing area, thereby correspondingly forming a hollow pattern of the wafer. The material at the notch is removed or dissolved from the wafer by one or more solutions; the wet etching uses an acid solution, an alkaline solution or a buffered oxide etching solution (BOE solution). By using a laser-induced writing to modify the wafer material once, and then using a wet etching solution to remove or release the wafer material in the laser writing area, the required tuning fork wafer overall structure can be accurately prepared, eliminating the complex process of multiple photolithography / mask processes, and quickly and efficiently realizing the patterning of the tuning fork wafer.

[0053] Table 1 Comparison between laser micro-nano processing and wire cutting processing

[0054]

[0055] As shown in Table 1, the laser micro-nano processing method provided by the present invention is compared with the traditional wire cutting processing method. The size structure of the tuning fork wafer prepared by different processing methods has different processing accuracy. Here, multiple size parameter values ​​of the tuning fork wafer product are selected for horizontal comparison. The size parameters include thickness T, arm width W2, arm width W1, total width W, ruler depth I, total length L, etc. The specific position marks of the above size parameters are as follows: Figure 4 As shown. The standard range of the thickness T of the tuning fork wafer product is between 0.330-0.340mm. The maximum value of the thickness T of the tuning fork wafer product prepared by the laser micro-nano processing method provided by the present invention is 0.334mm, the minimum value is 0.331mm, and the range (the difference between the maximum value and the minimum value) is 0.003mm. However, the maximum value of the thickness T of the tuning fork wafer product prepared by the traditional wire cutting processing method is 0.339mm, the minimum value is 0.330mm, and the range is 0.009mm.

[0056] The comparison results of the remaining size parameters are shown in Table 1, which will not be described one by one. From the extreme value of the size of the actually processed product, it can be seen that the size deviation range of the tuning fork wafer product prepared by the laser micro-nano processing method provided by the present invention is smaller, the difference between products is lower, and the consistency and stability are better.

[0057] like Figure 6 As shown in the figure, the laser micro-nano processing method provided by the present invention is compared with the traditional wire cutting processing method. The frequency distribution of tuning fork wafer products prepared in batches by different processing methods is different. 100 tuning fork wafer products are selected to measure the frequency point values. From the data in the figure, it can be seen that the frequency distribution of tuning fork wafers prepared by laser micro-nano processing is concentrated in the same set, while the frequency distribution of tuning fork wafers prepared by traditional wire cutting processing is more dispersed and the frequency error is large, resulting in the need to adjust the frequency of the tuning fork wafer in the later stage to meet the product frequency range standard requirements.

[0058] In one embodiment of the present invention, after the first laser etching and before the wet etching, the method further comprises: using a hydrofluoric acid solution to repair the surface of the wafer after the first laser writing. After the laser micro-nano processing and before the wet etching, a hydrofluoric acid thinning treatment is performed to remove defects from the material used for the first laser writing wafer.

[0059] The present invention also provides a tuning fork chip, which is prepared by the tuning fork chip micro-nano processing method using laser as described in any of the above embodiments. Specifically, the tuning fork chip (tuning fork crystal oscillator) refers to a quartz chip with a tuning fork-like appearance. The tuning fork chip can generate current pulses when resonating, so it can be widely used in various devices that require precise timing, such as clocks, mobile phones, tablet computers, microcomputers, calculators, etc.

[0060] At the same time, the tuning fork chip can also be used as a frequency control element to stabilize the operating frequency of the equipment. The tuning fork chip is also used in the fields of home appliance automatic control and industrial automatic control. In industrial control applications, the tuning fork chip can provide a stable frequency and time reference to help the equipment achieve precise control and scheduling.

[0061] In summary, the embodiments of the present invention provide a tuning fork wafer micro-nano processing method using laser, and a tuning fork wafer, the method comprising: providing a wafer; using a laser to write on the wafer once to form a pattern of the tuning fork wafer distributed at intervals; wet etching the wafer to form the wafer with a hollow pattern; coating the surface of the wafer with a metal layer, and using a second laser to etch the metal layer to form an electrode pattern of the tuning fork wafer; using a third laser to cut the wafer, and separating to obtain the tuning fork wafer. The method of laser micro-nano processing of the present invention is a maskless process, with a simple process flow and low production cost. The tuning fork wafer prepared by the method has high size and electrode precision and small frequency error.

[0062] It should be noted that although the present invention is disclosed as above by specific embodiments, the above embodiments are not intended to limit the present invention. Ordinary technicians in this field can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be based on the scope defined in the claims.

Claims

1. A tuning fork wafer micro-nano processing method using laser, characterized in that: The method comprises: providing a wafer; Using a single laser engraving process to form a pattern of tuning fork wafers distributed at intervals on the wafer; Performing wet etching on the wafer to form the wafer having a hollow pattern; Plating a metal layer on the surface of the wafer, and etching the metal layer by secondary laser to form an electrode pattern of the tuning fork wafer; Cutting the wafer by laser three times to obtain the tuning fork wafer after separation; The step of forming a pattern of the tuning fork wafers distributed at intervals on the wafer by laser writing once comprises: The laser writing the wafer once forms the outer contour of the tuning fork wafer, and accordingly forms a closed laser writing area on the wafer; wherein the laser writing area is interlocked with the tuning fork wafers distributed at intervals; The step of wet etching the wafer to form the wafer with a hollow pattern comprises: The wafer is immersed in an etching solution for wet etching to remove the wafer portion located in the laser writing area, thereby correspondingly forming a hollow pattern of the wafer.

2. The tuning fork wafer micro-nano processing method using laser according to claim 1, characterized in that: The power of the primary laser is smaller than the power of the secondary laser, and the power of the secondary laser is smaller than the power of the tertiary laser.

3. The tuning fork wafer micro-nano processing method using laser according to claim 1, characterized in that: The spot coverage range of the primary laser is 0.5-5 microns, and the hole center distance between adjacent spots is 1-10 microns.

4. The tuning fork wafer micro-nano processing method using laser according to claim 1, characterized in that: After the first laser etching and before the wet etching, the method further includes: using a hydrofluoric acid solution to repair the surface of the wafer after the first laser etching.

5. The tuning fork wafer micro-nano processing method using laser according to claim 1, characterized in that: The laser pulse width of the secondary laser is picoseconds or femtoseconds.

6. The tuning fork wafer micro-nano processing method using laser according to claim 1, characterized in that: The wavelengths of the three lasers are selected from 1064nm, 532nm or ultraviolet band.

7. The tuning fork wafer micro-nano processing method using laser according to claim 1, characterized in that: The wet etching adopts an acid solution, an alkaline solution or a buffered oxide etching solution.

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