Self-stopping thinning method of crystal wafer and application of self-stopping thinning method
By etching cavities on the crystal wafer and growing a metal layer at the bottom of the cavity, and utilizing the sudden change in the grinding wheel current parameter of the thinning machine to achieve automatic stop, the problem of insufficient thickness control accuracy during the thinning process of the crystal wafer is solved, the yield rate is improved and the cost is reduced.
Patent Information
- Application Number
- CN202511049995.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-28
- Publication Date
- 2025-12-19
AI Technical Summary
In existing technologies, the thickness control precision during the thinning process of crystal wafers is insufficient, resulting in large errors and low yield.
A cavity is etched on a crystal wafer and a metal layer is grown at the bottom of the cavity. Automatic stopping is achieved by using a sudden change in the current parameter of the thinning mill wheel. Combined with polishing, a crystal thin film of a predetermined thickness is formed.
It significantly reduces errors in the thin film/thin wafer fabrication process, improves thickness control accuracy and yield, saves on subsequent process steps, and reduces costs.
Smart Images
Figure CN121171925A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application relates to a self-stopping thinning method of a crystal wafer and application thereof, and belongs to the technical field of wafer processing. BACKGROUND
[0002] With the advancement of Moore's law, the density of chip transistors is increasing rapidly, and the packaging volume needs to be reduced synchronously to meet the light and thin requirements of mobile devices such as smart phones and wearable devices. Mechanical thinning directly reduces the height and volume of chip packaging by reducing the thickness of the wafer (such as reducing a 12-inch silicon wafer to below 50 microns). However, the essence of mechanical thinning is mechanical grinding, and the control accuracy of the target thickness is often poor. Errors of tens of microns or even a few microns are fatal to 20-50 micron thin films. Therefore, how to better improve the thickness control accuracy of thinning is a big problem in the current mechanical thinning process. SUMMARY
[0003] In order to solve the problem of low yield rate caused by insufficient thickness control accuracy in the prior art of crystal wafer thinning, the application provides a self-stopping thinning technical solution of a crystal wafer. A metal layer is arranged in the crystal wafer, so that the grinding wheel current of the grinding wheel of the thinning machine suddenly increases when the grinding wheel contacts the metal layer during the thinning process. When the critical threshold is reached, the thinning is automatically stopped, thereby greatly reducing the errors generated in the preparation process of the thin film / thin wafer, and obtaining a crystal thin film or a thin wafer with a pre-set thickness.
[0004] The application adopts the following technical solution:
[0005] According to the first aspect of the application, a self-stopping thinning method of a crystal wafer is provided, comprising:
[0006] providing a crystal wafer, and etching the surface on one side of the crystal wafer to prepare at least one recessed cavity;
[0007] preparing a metal layer at the bottom of the recessed cavity;
[0008] using a thinning machine to thin the processing surface of the crystal wafer until the grinding wheel of the thinning machine contacts the metal layer, and the grinding wheel current of the thinning machine reaches a set threshold, and the thinning machine automatically stops the thinning work, wherein the processing surface is the surface of the crystal wafer on the side facing the recessed cavity or the side away from the recessed cavity.
[0009] Optionally, the self-stopping thinning method of the crystal wafer further comprises: polishing the surface of the crystal wafer after thinning to completely expose the metal layer to form a crystal thin film.
[0010] Optionally, before the self-stopping thinning method of the crystal wafer, the method further comprises:
[0011] a surface compound substrate on the surface of the wafer away from the processing surface.
[0012] Optionally, when the processing surface is the surface of the wafer facing the cavity, and the thickness of the wafer is 100-200 μm, the surface compound substrate on the surface of the wafer away from the processing surface comprises:
[0013] a surface film on the surface of the wafer away from the processing surface.
[0014] Optionally, when the processing surface is the surface of the wafer facing the cavity, and the thickness of the wafer is less than 100 μm, the surface compound substrate on the surface of the wafer away from the processing surface comprises:
[0015] a surface compound substrate on the surface of the wafer away from the processing surface.
[0016] Optionally, when the processing surface is the surface of the wafer away from the cavity, the surface compound substrate on the surface of the wafer away from the processing surface comprises:
[0017] a surface compound substrate on the surface of the wafer away from the processing surface.
[0018] Optionally, after the forming of the crystal thin film, the method further comprises:
[0019] removing the metal layer from the crystal thin film.
[0020] Optionally, the providing of the wafer is providing a wafer that has been pre-thinned and / or pre-polished.
[0021] Optionally, the hardness of the metal layer is greater than the hardness of the wafer.
[0022] Optionally, the polishing of the thinned surface of the wafer comprises:
[0023] polishing using a polishing liquid having a particle size of 0.12-1 μm.
[0024] Optionally, the wafer is a semiconductor wafer.
[0025] According to a second aspect of the present application, there is provided an application of the self-stop thinning method of the wafer in the preparation of a crystal thin film and / or a wafer.
[0026] The present application has the following advantages:
[0027] (1) The thickness of the etched wafer is calculated, i.e. the thickness removed, and then a self-stop thinning method is used to obtain a single crystal thin film with accurate thickness.
[0028] (2) The metal layer designed for self-thinning stop can be designed according to the subsequent application of the thin film and used as an electrode structure, thereby saving the subsequent process flow and reducing the cost. BRIEF DESCRIPTION OF DRAWINGS
[0029] Figure 1 A process flow chart of the self-thinning stop technology of the present application;
[0030] Figure 2 A process flow chart of the self-thinning stop technology (cavity side thinning) of the embodiment of the present application;
[0031] Figure 3 A process flow chart of the self-thinning stop technology (backside thinning) of the embodiment of the present application. DETAILED DESCRIPTION
[0032] The present application will be described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.
[0033] Unless otherwise specified, the raw materials in the embodiments of the present application are purchased through commercial channels.
[0034] Unless otherwise specified, the test methods are all conventional methods, and the instrument settings are all recommended settings of the manufacturers.
[0035] The thickness error problems currently faced by the wafer thinning technology in the prior art mainly include the following aspects: (1) original wafer thickness error, the thickness of the wafer out of the factory has an error of ±20 μm, and the thicknesses of the thin wafers obtained by thinning processing in the same batch are inconsistent; (2) thinning machine processing error, in the thinning process of the wafer thinning machine, the grinding wheel often has wear, causing the thickness of the thinned wafer to be larger than the set value; (3) measurement error of the thickness measuring device, the thickness measurement of the wafer to be processed before processing often produces measurement error due to the thickness measuring device itself or external factors. When the above multiple errors occur at the same time, the error value is large and the thickness is unqualified, thereby reducing the thinning yield. To solve at least one of the foregoing technical problems, the present application provides a self-thinning stop technical solution, which comprises: thinning and removing a certain thickness from a sample, and then polishing; etching the surface of the sample, the etching depth being the total thickness of the sample minus the set value of the thickness of the thin film; growing a metal layer at the bottom of the etched cavity. Thinning the sample again, when the metal layer is thinned, the current parameter of the thinning machine is increased and the thinning is stopped; polishing the surface of the sample to expose the metal layer. The present application etches a certain depth structure and "buries" a metal with high hardness, so that the current parameter of the grinding wheel of the thinning machine suddenly becomes large when the grinding wheel contacts the metal, and the thinning is stopped. This technical solution is not only limited to the thinning processing of the wafer but also extends to the thinning processing of the semiconductor wafer, thereby greatly reducing the error generated in the process of preparing the thin film / thin wafer and obtaining the wafer thin film or the thin wafer with the pre-set thickness.
[0036] According to an embodiment of the present application, a self-stop thinning method of a crystal wafer, as shown in the accompanying drawings, comprises: Figure 1
[0037] S1, providing a crystal wafer, and etching a surface of one side of the crystal wafer to prepare at least one cavity;
[0038] S2, preparing a metal layer at the bottom of the cavity;
[0039] S3, using a thinning machine to thin the processing surface of the crystal wafer until the grinding wheel of the thinning machine contacts the metal layer, and the grinding wheel current of the thinning machine reaches a set threshold value, the thinning machine automatically stops the thinning work, wherein the processing surface is the surface of the side of the crystal wafer facing the cavity or the side away from the cavity.
[0040] In one embodiment, the self-stop thinning method of the crystal wafer further comprises:
[0041] S4, polishing the surface of the crystal wafer after thinning to completely expose the metal layer to form a crystal thin film.
[0042] The specific etching method for etching the surface to prepare at least one cavity is not strictly limited, and the etching method is selected according to the etching depth and the type of etching material, for example, dry etching and wet etching. The prepared cavity refers to a pattern with a certain depth etched on the surface of the crystal wafer, which includes but is not limited to a circle, a rectangle or any irregular pattern, or an electrode pattern required for subsequent thin film application, for example, the cavity is a hole when the pattern is a circle, the cavity is a groove when the pattern is a rectangle, and the cavity is a channel when the pattern is a line. A plurality of cavities can be arranged in a matrix or randomly, for example, a matrix of holes.
[0043] Preparing a metal layer at the bottom of the cavity refers to growing a metal layer at the bottom of the etched pattern. The method of growing the metal layer and the metal material can be selected as needed, for example, atomic layer deposition, electrochemical deposition or PVD sputtering, and the metal layer can be made of chromium, nickel, copper, aluminum, titanium, etc.
[0044] When the processing surface is the surface of the side of the crystal wafer facing the cavity, the process is more suitable for materials that can be etched deeper, such as silicon.
[0045] When the processing surface is the surface of the side of the crystal wafer away from the cavity, the process is more suitable for materials that are difficult to etch, such as lithium niobate or lithium tantalate. Because the etching is difficult, the back surface is thinned after etching.
[0046] In one embodiment, the method further comprises, before the step of thinning the processing surface of the wafer:
[0047] bonding a substrate to the surface of the wafer opposite to the processing surface.
[0048] The selection of the processing surface and the substrate depends on the etching difficulty of the wafer. When the etching difficulty of the wafer is high, the wafer can only be etched to a small thickness (2-20 μm), and thus a substrate is bonded to the surface of the wafer opposite to the processing surface, and the wafer is thinned from the surface opposite to the processing surface. When the etching difficulty of the wafer is low, the wafer can be etched to a large thickness range, and thus a substrate is bonded to the surface of the wafer opposite to the processing surface, and the wafer is thinned from the surface opposite to the processing surface. When the target thickness of the wafer is less than 100 μm, a bonding substrate is preferred. When the target thickness of the wafer is between 100 μm and 200 μm, a film is preferred.
[0049] In one embodiment, when the processing surface is the surface of the wafer opposite to the processing surface, and the thickness of the wafer is between 100 μm and 200 μm, the step of bonding a substrate to the surface of the wafer opposite to the processing surface comprises bonding a film to the surface of the wafer opposite to the processing surface. The film can be a thermal debonding film or an ultraviolet debonding film.
[0050] In one embodiment, when the processing surface is the surface of the wafer opposite to the processing surface, and the thickness of the wafer is less than 100 μm, the step of bonding a substrate to the surface of the wafer opposite to the processing surface comprises bonding a substrate to the surface of the wafer opposite to the processing surface. The bonding method is not limited, and can be temporary bonding or permanent bonding. Direct bonding is an advanced material connection technology, which does not need any intermediate adhesive (such as glue, solder or alloy), and only relies on the interaction force (mainly van der Waals force, hydrogen bond, and possibly covalent bond at high temperature) between the atoms or molecules on the surface of two highly flat, clean and smooth materials to achieve direct and permanent bonding at the atomic level.
[0051] In one embodiment, when the processing surface is the surface of the wafer opposite to the processing surface, the step of bonding a substrate to the surface of the wafer opposite to the processing surface comprises bonding a substrate to the surface of the wafer opposite to the processing surface. The material and thickness of the substrate can be selected as needed, and the substrate can be a silicon wafer.
[0052] In one embodiment, after the forming of the crystal thin film, the method further comprises: removing the metal layer from the crystal thin film. The metal layer can also be not removed but reserved as an electrode.
[0053] In one embodiment, the providing of the crystal wafer is providing a crystal wafer that has been pre-thinned and / or pre-polished. The purpose of the pre-thinning and / or pre-polishing is to remove a certain thickness to reduce the difficulty and cost of subsequent etching.
[0054] In one embodiment, the hardness of the metal layer is greater than the hardness of the crystal wafer. The relationship between the hardness is limited because the core technology improvement of the present application is to use the fact that the grinding wheel current parameter suddenly increases when the grinding wheel contacts the metal, specifically to provide a thinning machine and set a threshold value for the grinding wheel current of the thinning machine, use the thinning machine to thin one side of the crystal wafer, when the grinding wheel contacts the metal layer, because the hardness of the metal layer is greater than the hardness of the crystal wafer, the hardness of the material in the grinding process of the thinning machine increases, and the parameter current suddenly increases, that is, the grinding wheel current suddenly increases, so a program can be set for the thinning machine: when the grinding wheel current exceeds a certain threshold value during the grinding process, the thinning machine automatically ends the grinding.
[0055] In one embodiment, the polishing of the thinned surface of the crystal wafer comprises: using a polishing liquid with a particle size of 0.12-1 μm for polishing. The particle size range of the polishing liquid aims to achieve the polishing removal of the crystal wafer and the retention of the metal layer due to its high hardness. The particle size is too large and the roughness is relatively large, and the metal layer will also be polished to a certain extent. The composition and particle size of the polishing liquid can be selected as needed, for example, when the crystal wafer is lithium niobate or lithium tantalate wafer, silica polishing liquid can be used, and when the crystal wafer is quartz or sapphire wafer, alumina polishing liquid can be used.
[0056] In one embodiment, the thickness of the metal layer is less than the thickness of the recess.
[0057] In one embodiment, the crystal wafer is a semiconductor crystal wafer. The material of the crystal wafer is selected from at least one of silicon, lithium niobate, lithium tantalate, silicon nitride, gallium oxide, quartz, and sapphire.
[0058] According to one embodiment of the present application, a self-stopping thinning method for the above-mentioned crystal wafer is further provided for application in the preparation of a crystal thin film and / or a wafer.
[0059] In order to more clearly illustrate the technical solutions of the present application, the following will combine the accompanying drawings to Figures 2-3 The specific embodiment cases are described as follows:
[0060] Example 1
[0061] A process for preparing 100-micron-thick 8-inch single-crystal silicon thin films from a self-stopping thinning process is shown in FIG. 1. Figure 2
[0062] Step 1: Thinning and polishing pretreatment
[0063] The 8-inch silicon wafer was adsorbed on the vacuum chuck of a thinning machine, and the upper surface was thinned using a 320-mesh and 8000-mesh grinding wheel to 203 microns. The wafer was then transferred to a polishing machine for polishing to remove the damaged layer on the surface, and the final thickness of the silicon was about 200 microns.
[0064] Step 2: Preparation of cavities
[0065] A mask with a plurality of cavities uniformly distributed was designed, the cavities were hole-shaped with a diameter of 1 mm. The silicon surface was etched to a depth of 100 microns by dry etching to form a hole with a diameter of 1 mm. The specific operation is as follows: Cr hard mask was used, and the pattern of the cavities was transferred to the mask layer by deep ultraviolet lithography technology. An inductively coupled plasma (ICP) etching device was used, and an SF6 / CHF3 mixed gas atmosphere was adopted. The radio frequency power was set to 13 MHz high frequency source power, and the chamber pressure was maintained at 25 mTorr. A laser interferometer was used to measure the etching depth in real time, and the etching was stopped until the depth reached 100 microns. Wet etching was used to remove the mask, and dilute hydrofluoric acid was used for simple etching on the sidewall to reduce the roughness.
[0066] Step 3: Preparation of metal layer
[0067] A 100-nm-thick copper layer was grown at the bottom of the cavity. The specific operation is as follows: The copper foil and the silicon substrate were cleaned by ultrasonic cleaning with acetone and ethanol for 10 minutes each, and then dried with nitrogen. The silicon substrate was subjected to plasma activation (Ar plasma, power 50 W, time 5 minutes) to enhance the surface reactivity. The precursor was selected as β-diketone (such as Cu(acac)2). The precursor pulse time was set to 0.5-1.0 seconds, the inert gas purge time was 15 seconds (Ar or N2), the plasma power was 200 W (reducing agent H2), the deposition temperature was 160°C (plasma assisted), the reaction chamber pressure was 0.5 Torr, the single cycle growth thickness was 0.1 nm / cycle, and the total cycle number was 1000.
[0068] Step 3: Composite substrate (masking film)
[0069] A 120-micron-thick uv debonding film was attached to the back of the silicon wafer.
[0070] Step 4: Thinning
[0071] The thinning machine setting program, the parameter current is greater than 10A, the thinning is automatically stopped. A 120-micron-thick uv debonding film is pasted on the back of the silicon wafer, which is placed on the sample table of the thinning machine and vacuum-sucked, 80 microns are removed by coarse thinning using a 320-mesh grinding wheel, and then the silicon wafer is continuously thinned by an 8000-mesh grinding wheel until the grinding wheel of the thinning machine contacts the metal layer, the thinning machine prompts that the parameter current is greater than 10A, and the thinning is stopped.
[0072] Step 5: Polishing
[0073] Then the thinned film-coated silicon wafer is transferred to the polishing disc clamp, 120nm of silica polishing liquid is used, the pressure is 20kg, and the polishing is performed for 30min, so as to remove the residual damage layer and completely expose the electrode layer, and then the wafer is cleaned by ultrasonic deionized water, to obtain a thin film silicon wafer with an electrode.
[0074] Example 2
[0075] The process of preparing a 10-micron-thick 8-inch single-crystal lithium niobate thin film by self-stopping thinning is as shown in Figure 3
[0076] Step 1: Preparing a cavity
[0077] A clean 8-inch lithium niobate wafer (Y-128, thickness 500um) is prepared, a cavity with a depth of 10 microns and a line width of 1 millimeter is processed on the surface by dry etching, and the cavity is a grid channel structure that divides the lithium niobate surface into a 1cm×1cm rectangular array. The specific operation is as follows: a Cr hard mask is used, and the pattern of the cavity is transferred to the mask layer by deep ultraviolet lithography technology. An inductively coupled plasma (ICP) etching device is used, an SF6 / CHF3 mixed gas atmosphere is adopted, the radio frequency power is set to 13MHz high frequency source power, the chamber pressure is maintained at 25mTorr low pressure. A laser interferometer is used to measure the etching depth in real time until the depth reaches 10 microns. The mask is removed by wet etching, and a simple etching of dilute hydrofluoric acid is performed on the sidewall to reduce the roughness.
[0078] Step 2: Preparing a metal layer
[0079] A 100 nm thick copper layer is grown on the bottom of the cavity, and the specific operation is as follows: the copper foil, silicon substrate is cleaned, and ultrasonic cleaning is performed for 10 minutes with acetone and ethanol, and then dried with nitrogen. The silicon substrate is subjected to plasma activation (Ar plasma, power 50 W, time 5 minutes) to enhance the surface reactivity. The precursor is selected from β-diketones (such as Cu(acac)2). The precursor pulse time is set to 0.5-1.0 seconds, the inert gas purging time is 15 seconds (Ar or N2), the plasma power is 200 W (reducing agent H2), the deposition temperature is 160°C (plasma assisted), the reaction cavity pressure is 0.5 Torr, the single cycle growth thickness is 0.1 nm / cycle, and the total cycle number is 1000 times.
[0080] Step 3: Composite substrate (bonding)
[0081] An 8-inch silicon wafer is directly bonded with the concave surface of an 8-inch lithium niobate, and the specific operation is as follows: the silicon wafer is cleaned for 10-20 minutes, the lithium niobate is activated with hydrochloric acid (10% vol) for 30 seconds to remove the surface oxide layer, and then subjected to plasma activation (Ar / O2 mixed gas, power 200 W, time 90 seconds) to improve the surface hydrophilicity. A high-precision alignment machine is used to tightly bond the silicon and lithium niobate structure surfaces, and an initial pressure of 0.1 MPa (N2 atmosphere) is applied.
[0082] Step 4: Thinning
[0083] The thinning machine is set to a program with a current greater than 10 A and automatic stopping. The directly bonded wafer is cleaned and placed on the sample table of the thinning machine for vacuum adsorption. The 1000# and 3000# grinding wheels of the thinning machine are used for processing until the 3000# grinding wheel of the thinning machine contacts the metal layer. The thinning machine prompts that the current is greater than 10 A, and the thinning stops.
[0084] Step 5: Polishing
[0085] Then the thinned directly bonded wafer is transferred to a polishing disc, and a 120 nm silicon oxide polishing liquid is used with a pressure of 20 kg for 30 minutes to remove the residual damage layer and completely expose the electrode layer. Then the wafer is ultrasonically cleaned with deionized water to obtain a thin film silicon wafer with electrodes.
[0086] Step 6: Removing the metal layer by peeling
[0087] The metal layer on the thin film silicon wafer with electrodes is peeled off to obtain a thin film silicon wafer.
[0088] Example 3
[0089] The process for preparing a 10 micron thick 6-inch single crystal lithium tantalate thin film by self-stopping thinning is as shown in Figure 3
[0090] Step 1: Preparation of cavities
[0091] A clean 6-inch lithium tantalate wafer (Z-cut, thickness 500 um) was prepared, and a cavity with a depth of 10 microns and a line width of 1 millimeter was processed on the surface using dry etching. The cavity was a grid channel structure that divided the lithium niobate surface into a 1 cm x 1 cm rectangular array. The following steps were taken: A Cr hard mask was used, and the pattern of the cavity was transferred to the mask layer using deep ultraviolet lithography technology. An inductively coupled plasma (ICP) etching device was used, and an SF6 / CHF3 mixed gas atmosphere was adopted. The radio frequency power was set to 13 MHz, the high frequency source power was set to 13 MHz, and the chamber pressure was maintained at 25 mTorr. A laser interferometer was used to measure the etching depth in real time, and the process was stopped when the depth reached 10 microns. The mask was removed using wet etching, and a simple etching process was performed on the sidewall using dilute hydrofluoric acid to reduce the roughness.
[0092] Step 2: Preparation of metal layer
[0093] A 100 nm thick copper layer was grown on the bottom of the cavity. The following steps were taken: The copper foil and silicon substrate were cleaned by ultrasonic cleaning with acetone and ethanol for 10 minutes each, and then dried with nitrogen. The silicon substrate was plasma activated (Ar plasma, power 50 W, time 5 minutes) to enhance the surface reactivity. The precursor was selected as β-diketone (such as Cu(acac)2). The precursor pulse time was set to 0.5-1.0 seconds, the inert gas purge time was 15 seconds (Ar or N2), the plasma power was 200 W (reducing agent H2), the deposition temperature was 160°C (plasma assisted), the reaction chamber pressure was 0.5 Torr, the single cycle growth thickness was 0.1 nm / cycle, and the total cycle number was 1000.
[0094] Step 3: Composite substrate (bonding)
[0095] The 8-inch silicon wafer was directly bonded to the 6-inch lithium tantalate cavity surface. The following steps were taken: The silicon wafer was cleaned for 10-20 minutes, the lithium niobate was activated with hydrochloric acid (10% vol) for 30 seconds to remove the surface oxide layer, and then plasma activated (Ar / O2 mixed gas, power 200 W, time 90 seconds) to improve the surface hydrophilicity. A high-precision alignment machine was used to tightly bond the silicon and lithium niobate structure surfaces, and an initial pressure of 0.1 MPa (N2 atmosphere) was applied.
[0096] Step 4: Thinning
[0097] The thinning machine was set to a current greater than 10 A, and the thinning was automatically stopped. The directly bonded silicon surface was cleaned and placed on the sample stage of the thinning machine for vacuum adsorption. The 1000# and 3000# grinding wheels of the thinning machine were used for processing until the 3000# grinding wheel of the thinning machine contacted the metal layer. The thinning machine prompted that the current was greater than 10 A, and the thinning was stopped.
[0098] Step 5: Polishing
[0099] Then the thinned direct bonding wafer is transferred to a polishing disk, and polished for 30 min with 120 nm silicon oxide polishing liquid under a pressure of 20 kg to remove the residual damage layer and completely expose the electrode layer. The wafer is then cleaned with deionized water under ultrasonic vibration to obtain a thin film silicon wafer with an electrode.
[0100] Step 6: Stripping the metal layer
[0101] The metal layer on the thin film silicon wafer with an electrode is stripped to obtain a thin film silicon wafer.
[0102] The above is only a few embodiments of the present application, and does not limit the present application in any form. Although the preferred embodiments are disclosed above, the present application is not limited thereto. Any skilled person in the art can make some changes or modifications to the above disclosed technical content without departing from the scope of the technical solution of the present application, and such changes or modifications are equivalent to equivalent embodiments, and all of them are within the scope of the technical solution.
Claims
1. A self-stopping thinning method for crystal wafers, characterized in that, include: A crystal wafer is provided, and at least one cavity is formed by etching a surface on one side of the crystal wafer; A metal layer is prepared at the bottom of the cavity; The thinning machine is used to thin the processing surface of the crystal wafer until the grinding wheel of the thinning machine contacts the metal layer, and the grinding wheel current of the thinning machine reaches a set threshold. At this point, the thinning machine automatically stops the thinning operation. The processing surface is the surface of the crystal wafer facing the cavity or away from the cavity.
2. The self-stopping thinning method for crystal wafers according to claim 1, characterized in that, Also includes: The thinned surface of the crystal wafer is polished until the metal layer is fully exposed to form a crystal thin film.
3. The self-stopping thinning method for crystal wafers according to claim 1, characterized in that, Before using a thinning machine to thin the processing surface of the crystal wafer, the process further includes: A surface composite substrate on the side of the crystal wafer facing away from the processing surface.
4. The self-stopping thinning method for crystal wafers according to claim 3, characterized in that, When the processed surface is the surface of the crystal wafer facing the cavity, and the thickness of the crystal wafer is 100–200 μm, the composite substrate on the surface of the crystal wafer facing away from the processed surface includes: A film is applied to the surface of the crystal wafer facing away from the processing surface.
5. The self-stopping thinning method for crystal wafers according to claim 3, characterized in that, When the processed surface is the surface of the crystal wafer facing the cavity, and the thickness of the crystal wafer is less than 100 μm, the composite substrate on the surface of the crystal wafer facing away from the processed surface includes: A surface-bonded substrate on the side of the crystal wafer opposite to the processing surface.
6. The self-stopping thinning method for crystal wafers according to claim 3, characterized in that, When the processed surface is the surface of the crystal wafer facing away from the cavity, the composite substrate on the surface of the crystal wafer facing away from the processed surface includes: A surface-bonded substrate on the side of the crystal wafer opposite to the processing surface.
7. The self-stopping thinning method for crystal wafers according to claim 2, characterized in that, After forming the crystalline thin film, the method further includes: The metal layer is removed from the crystalline thin film.
8. The self-stopping thinning method for crystal wafers according to claim 1, characterized in that, The crystal wafer provided is a crystal wafer that has undergone pre-thinning and / or pre-polishing treatment.
9. The self-stopping thinning method for crystal wafers according to claim 1, characterized in that, The hardness of the metal layer is greater than the hardness of the crystal sheet.
10. The application of the self-stopping thinning method of the crystal wafer according to any one of claims 1 to 9 in the preparation of crystal thin films and / or wafers.