Manufacturing method of quartz wafer and quartz wafer

Abstract

The invention provides a quartz wafer manufacturing method and a quartz wafer. Comprising the following steps: selecting quartz blank pieces with similar frequencies; performing double-sided grinding on the quartz blank piece; polishing the front surface and the back surface of the quartz blank piece; arranging the plurality of quartz wafers and forming a lamination with a cylindrical structure; putting the laminated sheet into a drying oven for preheating, and pouring a wax loosening agent melt on the laminated sheet to form a lump crystal; carrying out linear cutting along the upper bottom surface of the lump crystal to obtain a lump crystal with a preset shape; polishing the circumferential direction of the lump crystal; and carrying out hot melting separation on the lump crystal to obtain a plurality of quartz crystal wafers with preset thicknesses and preset shapes. According to the invention, the plurality of quartz wafers are stacked and matched with the wax loosening agent melt to form the lump crystal, so that the overall thickness of the quartz wafer assembly is improved, the overall processing speed can be improved, the vibration of a single quartz wafer in the cutting process is reduced, and the rejection rate of the quartz wafers in the cutting process is further reduced.

Description

Technical Field

[0001] The invention relates to the field of quartz wafer processing, in particular to a manufacturing method of a quartz wafer and the quartz wafer. Background Art

[0002] The dimensions of the quartz crystal directly affect the resistance, frequency jump point and other indicators of the crystal resonator. As the dimensions of the quartz resonator decrease, due to the inherent characteristics of the quartz crystal, the frequency jump point will also deteriorate due to the influence of various coupled vibrations, and the difficulty of achieving the frequency jump point indicator of the resonator will be greatly increased. When the parallelism and flatness of the quartz crystal surface are low, the resistance temperature characteristics will also deteriorate, the activity will decrease or even stop oscillating, especially for high-frequency chips, which are thinner and have a more significant impact.

[0003] However, the manufacturing process of quartz crystal generally involves cutting and grinding to modify the shape of the quartz wafer. When a wire cutting machine is used to cut the original quartz wafer, quartz wafers with uneven thickness and large frequency differences are susceptible to greater impact force, causing the original quartz wafer to be scrapped, wasting production resources and increasing costs. Summary of the invention

[0004] The object of the present invention is to provide a method for manufacturing a quartz wafer and a quartz wafer to solve the technical problems listed in the background technology.

[0005] According to one aspect of the present invention, there is provided a method for manufacturing a quartz wafer, comprising:

[0006] Step 1, select a quartz blank with a similar frequency;

[0007] Step 2, double-sided grinding of the quartz blank sheet is performed, and the upper surface and the lower surface of the quartz blank sheet are ensured to have the same removal rate;

[0008] Step 3, polishing the front and back sides of the quartz blank sheet, and then cleaning the quartz blank sheet using a cleaning device to obtain a quartz blank sheet with a predetermined thickness;

[0009] Step 4, repeating the above steps 1 to 3 to obtain a plurality of quartz blank sheets with a predetermined thickness, and then arranging the plurality of quartz wafers with the predetermined thickness to form a stacked sheet with a columnar structure;

[0010] Step 5: Place the stacked sheets in an oven for preheating, and pour the wax loosening agent melt on the stacked sheets to form a crystal;

[0011] Step 6: cutting along the upper bottom surface of the ingot and / or grinding along the circumference of the ingot to obtain an ingot with a predetermined shape;

[0012] Step 7: Polishing the circumference of the ingot crystal until the circumference of the ingot crystal has the same smoothness as the front and back sides of the quartz wafer;

[0013] Step 8: hot-melt separate the ingot crystal, and obtain a plurality of quartz wafers with a predetermined thickness and a predetermined shape after cleaning and drying.

[0014] Preferably or optionally, step 2 comprises the following steps:

[0015] Step 21, placing the quartz blank into an annealing furnace for annealing, and taking it out after cooling to room temperature;

[0016] Step 22, placing the annealed quartz blank into the planetary wheel for double-sided grinding, so that the upper surface and the lower surface of the quartz blank begin to be thinned at the same time;

[0017] Step 23, collecting a first height difference and a second height difference of the quartz blank at predetermined intervals; the first height difference is a height difference between a current upper surface and a preset upper surface, and the second height difference is a height difference between a current lower surface and a preset lower surface;

[0018] Step 24: when the first height difference and the second height difference are inconsistent, performing a first round of deviation correction on the grinding parameters based on the first control strategy;

[0019] Step 25, continuing grinding based on the first round of deviation correction, when the difference between the first height difference and the second height difference is inconsistent, performing deviation correction of the second control strategy based on the deviation correction improvement of the difference between the first height difference and the second height difference for two adjacent times;

[0020] Step 26, repeating step 25, performing multiple rounds of grinding until the absolute value of the difference between the first height difference and the second height difference is less than a threshold;

[0021] Step 27, until the current upper surface is consistent with the preset upper surface and / or the current lower surface is consistent with the preset lower surface, the double-sided grinding of the quartz blank sheet is completed.

[0022] Preferably or optionally, the method for determining the first control strategy includes:

[0023] Step 241: When the difference Δh between the first height difference and the second height difference i When it is greater than the positive threshold, the normal force P between the grinding disc and the quartz blank sheet and / or the rotational linear velocity v of the grinding disc acting on the upper surface of the quartz blank sheet is increased, and / or the normal force P between the grinding disc and the quartz blank sheet and / or the rotational linear velocity v of the grinding disc acting on the lower surface of the quartz blank sheet is reduced;

[0024] Step 242: When the difference Δh between the first height difference and the second height difference iWhen it is less than a negative threshold, the normal force P between the grinding disc and the quartz blank sheet acting on the upper surface of the quartz blank sheet and / or the rotational linear velocity v of the grinding disc are reduced, and / or the normal force P between the grinding disc and the quartz blank sheet acting on the lower surface of the quartz blank sheet and / or the rotational linear velocity v of the grinding disc are reduced.

[0025] Preferably or optionally, the first control strategy is determined by a preset control analysis model, and the preset control analysis model is based on a semi-empirical model dh=K p Pvdt design; where Kp is a coefficient related to the material and distribution of the grinding point, the polishing fluid and the temperature; P is the normal force between the grinding point and the quartz blank; and v is the relative linear velocity between the grinding point and the quartz blank.

[0026] Preferably or optionally, the calculation formula for the deviation correction improvement degree of the difference between two adjacent first height differences and the second height difference is: ec = (Δh i -Δh i+1 ) / Δh i ; where ec represents the degree of correction improvement, Δh i It represents the difference between the first height difference and the second height difference before the deviation correction of a wheel, Δh i+1 It indicates the difference between the first height difference and the second height difference after the deviation of the wheel is corrected.

[0027] Preferably or optionally, the method for determining the second control strategy includes:

[0028] Step 251, calculating the compensation control amount according to the deviation correction improvement degree, and correcting the first control strategy multiple times to obtain the second control strategy.

[0029] Preferably or optionally, the grinding disc is a copper-added cast iron grinding disc or a ductile iron grinding disc, and the grinding disc is used in combination with silicon carbide or aluminum oxide grinding powder for grinding.

[0030] Preferably or optionally, the height of the laminations is not greater than the bottom diameter of the laminations.

[0031] Preferably or optionally, the rosin melt is a mixture of ceresin and rosin heated and melted in an oven at 120-180° C.; the mass fraction ratio of ceresin to rosin in the mixture of ceresin and rosin is 1:1 to 2:1.

[0032] According to another aspect of the present invention, there is provided a quartz wafer obtained by using the above-mentioned method for manufacturing a quartz wafer.

[0033] The manufacturing method of the quartz wafer and the quartz wafer provided by the present invention have the following beneficial effects compared with the prior art: on the one hand, the present invention processes the quartz crystal by double-sided grinding, thereby improving the parallelism and flatness of the quartz wafer and reducing the scrap rate of the quartz wafer during the cutting process; on the other hand, by stacking multiple quartz wafers and adding loosening agent melt to form a crystal ingot, the overall thickness of the quartz wafer assembly is increased, which can not only improve the overall processing speed, but also reduce the vibration of a single quartz wafer during the cutting process, thereby reducing the scrap rate of the quartz wafer during the cutting process. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments:

[0035] Figure 1 It is a schematic flow chart of the method for manufacturing a quartz wafer in the present invention. DETAILED DESCRIPTION

[0036] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in 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 present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0037] See attached Figure 1 This embodiment provides a method for manufacturing a quartz wafer, comprising the following steps:

[0038] Step 1: Select quartz blanks with similar frequencies.

[0039] Specifically, the user grinds the silicon crystal rod and cuts it into quartz blanks with a predetermined thickness, which is at least twice the thickness of the target quartz wafer, preferably 0.55 mm in this embodiment, and then performs an initial frequency measurement on the quartz blanks, and selects quartz blanks with similar frequencies as quartz wafer originals for the next step of processing.

[0040] Step 2: Double-sided grinding is performed on the quartz blank sheet, and the upper surface and the lower surface of the quartz blank sheet are ensured to have the same removal rate.

[0041] Specifically, the step 2 includes the following steps: Step 21, placing the quartz blank sheet into an annealing furnace for annealing, and taking it out after cooling to room temperature; removing the internal stress of the quartz blank sheet material to avoid deformation of the quartz blank sheet due to changes in internal stress in subsequent processing. Step 22, placing the annealed quartz blank sheet into a planetary wheel for double-sided grinding, so that the upper surface and the lower surface of the quartz blank sheet begin to be thinned at the same time; in order to ensure that the upper surface and the lower surface of the quartz blank sheet have the same removal rate, this embodiment processes the quartz crystal by double-sided grinding, improves the parallelism and flatness of the quartz wafer, and reduces the scrap rate of the quartz wafer during the cutting process.

[0042] In addition, the present embodiment is also equipped with a corresponding control program for real-time deviation correction during double-sided grinding, so as to ensure that the upper and lower surfaces of the quartz blank have the same removal rate, thereby ensuring the parallelism of the wafer. Specifically, the step 2 also includes the following steps: step 23, collecting the first height difference and the second height difference of the quartz blank at predetermined intervals; the first height difference is the height difference of the current upper surface relative to the preset upper surface, and the second height difference is the height difference of the current lower surface relative to the preset lower surface; wherein the first height difference and the second height difference can be measured and detected using multiple sample points, that is, multiple detection points are set on the quartz blank to obtain a detection value closer to the true value. Step 24, when the first height difference and the second height difference are inconsistent, perform a first round of deviation correction on the grinding parameters based on the first control strategy;

[0043] The method for determining the first control strategy includes: step 241, when the difference Δh between the first height difference and the second height difference i When the height difference between the first and second height differences is greater than the positive threshold, the normal force P between the grinding disc and the quartz blank and / or the rotational linear velocity v of the grinding disc acting on the upper surface of the quartz blank are increased, and / or the normal force P between the grinding disc and the quartz blank and / or the rotational linear velocity v of the grinding disc acting on the lower surface of the quartz blank are decreased; Step 242, when the difference Δh between the first height difference and the second height difference is i When it is less than a negative threshold, the normal force P between the grinding disc and the quartz blank sheet acting on the upper surface of the quartz blank sheet and / or the rotational linear velocity v of the grinding disc are reduced, and / or the normal force P between the grinding disc and the quartz blank sheet acting on the lower surface of the quartz blank sheet and / or the rotational linear velocity v of the grinding disc are reduced.

[0044] The first control strategy is determined by a preset control analysis model, and the preset control analysis model is based on a semi-empirical model dh=K pPvdt design; where Kp is a coefficient related to the material and distribution of the grinding point, the polishing fluid and the temperature, P is the normal force between the grinding point and the quartz blank, and v is the relative linear speed between the grinding point and the quartz blank. Therefore, the user can directly design the corresponding control table or control change curve according to the preset control analysis model to achieve parameter adjustment of the normal force P between the grinding disc and the quartz blank, and the rotation linear speed v of the grinding disc.

[0045] Among them, the size of Kp is related to the material and distribution of the grinding points, the polishing liquid and the temperature, so the selection of the grinding disc is particularly important. If the hardness of the grinding disc is too large, the damage depth of the quartz wafer will be too large, the yield rate will be low, and it will be difficult to control. On the contrary, if the hardness of the grinding disc is too small, the grinding rate will be too slow, which will extend the manufacturing cycle of the quartz wafer. In this embodiment, the grinding disc is a copper-added cast iron grinding disc or a ductile iron grinding disc, and the grinding disc is matched with silicon carbide or aluminum oxide grinding powder for grinding, which can ensure the length of the grinding time, provide corresponding control time for the correction program, improve the accuracy of double-sided grinding, and ensure the parallelism of the quartz wafer.

[0046] Step 25, continue grinding based on the first round of deviation correction. When the difference between the first height difference and the second height difference is inconsistent, perform deviation correction of the second control strategy based on the correction improvement of the difference between the first height difference and the second height difference for two adjacent times; Step 26, repeat step 25, and perform multiple rounds of grinding until the absolute value of the difference between the first height difference and the second height difference is less than a threshold; Step 27, until the current upper surface is consistent with the preset upper surface and / or the current lower surface is consistent with the preset lower surface, and end the double-sided grinding of the quartz blank.

[0047] The calculation formula of the deviation correction improvement degree of the difference between two adjacent first height differences and the second height difference is: ec = (Δh i -Δh i+1 ) / Δh i ; Among them, ec represents the correction improvement, Δh i It represents the difference between the first height difference and the second height difference before the deviation correction of a wheel, Δh i+1 It represents the difference between the first height difference and the second height difference after the deviation of the wheel is corrected. Then, the compensation control amount is calculated according to the correction improvement degree, and the first control strategy is corrected multiple times to obtain the second control strategy, so that feedback control can be performed through the compensation control amount, which can quickly improve the convergence speed of the correction control system, that is, to ensure that the upper and lower sides have the same removal amount and removal speed.

[0048] Exemplarily, the formula for the compensation control amount is as follows: vc=f(ec), where vc represents the desired compensation control amount for the deviation correction, and f(ec) represents the PID algorithm that can make the deviation correction control system converge. It should be noted that when the deviation correction improvement ec is a negative value, the relevant parameters need to be adjusted in the opposite direction. As the number of deviation correction rounds increases, the deviation correction improvement ec gradually decreases to zero, that is, the removal rates on both sides are basically maintained at the same level.

[0049] Step 3: polish the front and back sides of the quartz blank sheet, and then use a cleaning device to clean the quartz blank sheet to obtain a quartz blank sheet with a predetermined thickness.

[0050] Step 4, repeat the above steps 1 to 3 to obtain a plurality of quartz blanks with a predetermined thickness, and then arrange a plurality of quartz wafers with a predetermined thickness to form a stack with a columnar structure. The height of the stack is not greater than the bottom diameter of the stack, and more preferably, the height of the stack is 0.5-0.8 times the bottom diameter of the stack. This can ensure the processing accuracy of subsequent wire cutting, ensure the stability of the stack as a whole, avoid the deviation of a single quartz wafer, and ensure the uniformity of the quartz wafer shape modification.

[0051] Step 5: preheat the stacked sheets in an oven, and pour the wax melt on the stacked sheets to form a crystal. The wax melt is a mixture of ceresin and rosin heated and melted in an oven at 120-180°C; the mass fraction ratio of ceresin to rosin in the mixture is 1:1 to 2:1.

[0052] Step 6: Cut along the upper bottom surface of the ingot and / or grind along the circumference of the ingot to obtain an ingot with a predetermined shape; by stacking multiple quartz wafers and adding a loosening agent melt to form an ingot, the overall thickness of the quartz wafer assembly is increased, which not only improves the overall processing speed, but also reduces the vibration of a single quartz wafer during the cutting process, thereby reducing the scrap rate of the quartz wafer during the cutting process.

[0053] Step 7: Polish the circumference of the ingot crystal until the circumference of the ingot crystal has the same smoothness as the front and back sides of the quartz wafer.

[0054] Step 8: hot-melt separate the ingot crystal, and obtain a plurality of quartz wafers with a predetermined thickness and a predetermined shape after cleaning and drying.

[0055] By processing the quartz wafer according to the process flow in the embodiment, a quartz wafer with a diameter of 14 mm, a thickness of 0.25 mm, a top and bottom surface roughness Sa less than 0.8 nm, and a resonance frequency of 40-45 MHz can be obtained.

[0056] It will be apparent to those skilled in the art that various modifications and variations may be made to the above exemplary embodiments of the present invention without departing from the spirit and scope of the present invention. Therefore, it is intended that the present invention covers modifications and variations of the present invention that fall within the scope of the appended claims and their equivalent technical solutions.

Claims

1. A method for manufacturing a quartz wafer, characterized in that: include: Step 1, select a quartz blank with a similar frequency; Step 2, double-sided grinding of the quartz blank sheet is performed, and the upper surface and the lower surface of the quartz blank sheet are ensured to have the same removal rate; Step 3, polishing the front and back sides of the quartz blank sheet, and then cleaning the quartz blank sheet using a cleaning device to obtain a quartz blank sheet with a predetermined thickness; Step 4, repeating the above steps 1 to 3 to obtain a plurality of quartz blank sheets with a predetermined thickness, and then arranging the plurality of quartz wafers with the predetermined thickness to form a stacked sheet with a columnar structure; Step 5: Place the stacked sheets in an oven for preheating, and pour the wax loosening agent melt on the stacked sheets to form a crystal; Step 6: cutting along the upper bottom surface of the ingot and / or grinding along the circumference of the ingot to obtain an ingot with a predetermined shape; Step 7: Polishing the circumference of the ingot crystal until the circumference of the ingot crystal has the same smoothness as the front and back sides of the quartz wafer; Step 8: hot-melt separate the ingot crystal, and obtain a plurality of quartz wafers with a predetermined thickness and a predetermined shape after cleaning and drying.

2. The method for manufacturing a quartz wafer according to claim 1, wherein: The step 2 comprises the following steps: Step 21, placing the quartz blank into an annealing furnace for annealing, and taking it out after cooling to room temperature; Step 22, placing the annealed quartz blank into the planetary wheel for double-sided grinding, so that the upper surface and the lower surface of the quartz blank begin to be thinned at the same time; Step 23, collecting a first height difference and a second height difference of the quartz blank at predetermined intervals; the first height difference is a height difference between a current upper surface and a preset upper surface, and the second height difference is a height difference between a current lower surface and a preset lower surface; Step 24: when the first height difference and the second height difference are inconsistent, performing a first round of deviation correction on the grinding parameters based on the first control strategy; Step 25, continuing grinding based on the first round of deviation correction, when the difference between the first height difference and the second height difference is inconsistent, performing deviation correction of the second control strategy based on the deviation correction improvement of the difference between the first height difference and the second height difference for two adjacent times; Step 26, repeating step 25, performing multiple rounds of grinding until the absolute value of the difference between the first height difference and the second height difference is less than a threshold; Step 27, until the current upper surface is consistent with the preset upper surface and / or the current lower surface is consistent with the preset lower surface, the double-sided grinding of the quartz blank sheet is completed.

3. The method for manufacturing a quartz wafer according to claim 2, wherein: The method for determining the first control strategy includes: Step 241: When the difference Δh between the first height difference and the second height difference i When it is greater than the positive threshold, the normal force P between the grinding disc and the quartz blank sheet and / or the rotational linear velocity v of the grinding disc acting on the upper surface of the quartz blank sheet is increased, and / or the normal force P between the grinding disc and the quartz blank sheet and / or the rotational linear velocity v of the grinding disc acting on the lower surface of the quartz blank sheet is reduced; Step 242: When the difference Δh between the first height difference and the second height difference i When it is less than a negative threshold, the normal force P between the grinding disc and the quartz blank sheet acting on the upper surface of the quartz blank sheet and / or the rotational linear velocity v of the grinding disc are reduced, and / or the normal force P between the grinding disc and the quartz blank sheet acting on the lower surface of the quartz blank sheet and / or the rotational linear velocity v of the grinding disc are reduced.

4. The method for manufacturing a quartz wafer according to claim 3, wherein: The first control strategy is determined by a preset control analysis model, which is based on a semi-empirical model dh=K p Pvdt design; where Kp is a coefficient related to the material and distribution of the grinding point, the polishing fluid and the temperature; P is the normal force between the grinding point and the quartz blank; and v is the relative linear velocity between the grinding point and the quartz blank.

5. The method for manufacturing a quartz wafer according to claim 4, wherein: The calculation formula of the deviation correction improvement degree of the difference between two adjacent first height differences and the second height difference is: ec = (Δh i -Δh i+1 ) / Δh i ; Where ec represents the degree of improvement in correction, Δh i It represents the difference between the first height difference and the second height difference before the deviation correction of a wheel, Δh i+1 It indicates the difference between the first height difference and the second height difference after the deviation of the wheel is corrected.

6. The method for manufacturing a quartz wafer according to claim 5, wherein: The method for determining the second control strategy includes: Step 251, calculating the compensation control amount according to the deviation correction improvement degree, and correcting the first control strategy multiple times to obtain the second control strategy.

7. The method for manufacturing a quartz wafer according to claim 1, wherein: The grinding disc is a copper-added cast iron grinding disc or a ductile iron grinding disc, and the grinding disc is used in combination with silicon carbide or aluminum oxide grinding powder for grinding.

8. The method for manufacturing a quartz wafer according to claim 1, wherein: The height of the laminations is not greater than the bottom diameter of the laminations.

9. The method for manufacturing a quartz wafer according to claim 1, wherein: The rosin melt is a state in which a mixture of ceresin and rosin is heated and melted in an oven at 120-180° C.; the mass fraction ratio of ceresin to rosin in the mixture of ceresin and rosin is 1:1 to 2:

1.

10. A quartz wafer obtained by the method for manufacturing a quartz wafer according to any one of claims 1 to 9.

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