Method for improving ultrasonic stripping efficiency of crystal and avoiding collision

Abstract

The invention discloses a method for improving crystal ultrasonic stripping efficiency and avoiding bumping, and belongs to the technical field of crystal ultrasonic stripping, and the method comprises the following steps: S1, selecting a ceramic plate according to the crystal size, heating the ceramic plate to 100 DEG C, and then preparing solid wax and ultrasonic stripping liquid, S2, uniformly smearing the solid wax on the upper surface of the ceramic plate, the method comprises the steps that firstly, a ceramic base plate is placed on a substrate, then the crystal is bonded to the upper surface of the ceramic base plate, bonding can be completed after cooling, the ceramic base plate is placed on a laser cutting device to be cut after bonding is completed, and the crystal is bonded to the ceramic base plate, so that collision of the crystal in the carrying process of thinning, laser cutting and ultrasonic stripping can be effectively avoided; edge breakage or notches of the crystal are effectively avoided, safety is improved, in addition, the crystal is bonded to the ceramic base plate, the situation that the crystal shakes along with a liquid medium under the condition that the crystal is too thin is avoided, and therefore the conduction effect of ultrasound in the crystal is weakened, and the crystal cannot be peeled off.

Description

[0001] The present invention relates to the technical field of crystal ultrasonic peeling, and more specifically, to a method for improving the efficiency of crystal ultrasonic peeling and avoiding collision. Background Art

[0002] Crystal ultrasonic peeling is a technique for separating wafers from crystal materials, mainly applied in fields such as semiconductor substrate processing. Compared with traditional peeling methods, crystal ultrasonic peeling can improve the peeling efficiency.

[0003] In the existing crystal ultrasonic peeling technology, after ultrasonic peeling is completed, the crystal is manually placed for grinding. During the process, it is easy to cause collision on the edge of the crystal, resulting in chipping or notching of the wafer after peeling; at the same time, when the silicon carbide crystal is peeled to a certain extent (about <2000μm), due to the crystal being too thin, it will shake in the aqueous liquid medium during the ultrasonic process, resulting in weakened ultrasonic effect and the wafer cannot be peeled normally. In addition, the traditional peeling liquid medium is pure water, and the ultrasonic energy propagation is unstable, and the peeling efficiency is poor. Summary of the Invention

[0004] The present invention mainly provides a method for improving the efficiency of crystal ultrasonic peeling and avoiding collision, which can solve the problems of poor peeling efficiency and collision proposed in the above background art.

[0005] To achieve the above object, the present invention provides the following technical solution: A method for improving the efficiency of crystal ultrasonic peeling and avoiding collision, comprising the following steps:

[0006] S1. Select a ceramic disk according to the crystal size, heat the ceramic disk to 100°C, and then prepare the solid wax and the ultrasonic peeling liquid.

[0007] S2. Uniformly apply the solid wax on the upper surface of the ceramic disk, then bond the crystal on the upper surface of the ceramic disk, and complete the bonding after cooling. After the bonding is completed, place it on a laser cutting device for cutting.

[0008] S3. Place the cut crystal at the bottom of the processing tank of the ultrasonic peeling equipment, then pour the prepared peeling liquid into the processing tank of the ultrasonic peeling equipment, and then perform ultrasonic peeling.

[0009] S4. Process the ultrasonic peeled crystal and the ceramic disk with a thinning device to complete the entire grinding process.

[0010] S5. After processing, place the remaining crystal and the ceramic disk on the upper surface of a heating plate to heat and melt the solid wax to remove the remaining crystal. Then, place the remaining crystal and the ceramic disk in an absolute ethanol solution for ultrasonic cleaning for 10 - 15 minutes, and use a dust-free cloth to wipe off the residual impurities on the surface.

[0011] Further, in S1, the crystals are divided into 6-inch crystals and 8-inch crystals. Among them, 160×10 ceramic trays are used for 6-inch crystals, and 220×10 ceramic trays are used for 8-inch crystals. The heating of the ceramic trays is the heating of the heating trays.

[0012] Further, the solid wax contains 65% paraffin wax, 15% stearic acid, 15% rosin, and 5% microcrystalline wax. The ultrasonic stripping liquid contains 68.5% basic liquid medium, 1% surfactant stock solution, 0.5% B regulator, and 30% organic solvent stock solution.

[0013] Further, in S2, the laser cutting is started by power supply. Under the assistance of the working gas, an original laser beam is generated, and the original laser beam is reflected by a reflecting mirror. It is cooled by the cooling water, changes the laser propagation direction, guides the laser beam to travel in the focusing direction, and finally cuts the crystal through the focusing of the laser focusing mirror.

[0014] Further, in S3, the ultrasonic stripping power is 300w, the time is 10 mins, and when the crystal thickness is <2000μm, the stripping efficiency is also shortened from the original 5 mins to 2 mins.

[0015] Further, in S5, the ultrasonic cleaning temperature of the absolute ethanol solution is 50°C.

[0016] Further, the basic liquid medium is pure water, and ultrasonic-assisted degassing for 30 minutes is required for the first processing. The surfactant stock solution is 50-60% octylphenol and 40-50% polyoxyethylene chain. The B regulator is an acid salt. The organic solvent stock solution is 40-50% pure water, 40-50% isopropanol, and 5-10% glycerol.

[0017] The beneficial effects of the method for improving the ultrasonic stripping efficiency of crystals and avoiding bumps in the present invention are as follows:

[0018] By bonding the crystal to the ceramic chassis, it can effectively avoid bumps during the handling of crystal thinning, laser cutting, and ultrasonic stripping, effectively avoid chipping or notching of the crystal, and improve safety. In addition, by bonding the crystal to the ceramic chassis, when the crystal is too thin, the crystal will not shake with the liquid medium, thereby weakening the conduction effect of ultrasound in the crystal and causing the crystal to be unable to be stripped. Finally, by re-preparing the ultrasonic liquid medium, it effectively ensures the good transmission of ultrasonic energy and protects the surface of silicon carbide from damage. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention will be further described in detail below with reference to the drawings and specific implementation methods.

[0020] Figure 1This is a schematic flow chart of a method for improving the ultrasonic peeling efficiency of crystals and avoiding collisions in the present invention. Detailed implementation manners

[0021] To make the technical solution of the present invention clearer, the following further describes the present invention in detail with reference to the accompanying drawings and specific embodiments.

[0022] Example 1

[0023] As Figure 1 shown, according to one aspect of the present invention, a technical solution is provided: a method for improving the ultrasonic peeling efficiency of crystals and avoiding collisions, including the following steps:

[0024] Step 1: Select a ceramic disk according to the crystal size, and heat the ceramic disk to 100 °C. Heating makes the solid wax in a good molten state, which can be more evenly applied on the ceramic disk, better bond with the crystal, and form a firm connection after cooling, facilitating subsequent operations such as cutting. At the same time, it can avoid uneven wax layer or weak bonding caused by too low temperature, affecting the fixing effect of the crystal. Then, the solid wax and the ultrasonic peeling liquid are configured;

[0025] Among them, the crystals are divided into 6-inch crystals and 8-inch crystals. Among them, 160×10 ceramic disks are used for 6-inch crystals, and 220×10 ceramic disks are used for 8-inch crystals, which can provide a suitable bearing platform for crystals of different sizes, ensure the stable placement of crystals in subsequent operations, is conducive to improving processing accuracy, and avoid crystal damage or processing deviation caused by inappropriate bearing. The heating of the ceramic disk is heating by a heating disk. In addition, the solid wax contains 65% paraffin wax (providing basic viscosity and formability), 15% stearic acid (improving the hardness and stability of the wax), 15% rosin (increasing viscosity and flexibility), 5% microcrystalline wax (improving the toughness and crack resistance of the wax), and the ultrasonic peeling liquid contains 68.5% basic liquid medium, 1% surfactant stock solution, 0.5% B regulator, and 30% organic solvent stock solution;

[0026] Among them, the basic liquid medium in the ultrasonic peeling liquid is pure water, as a peeling medium (reducing impurity interference and stable cavitation effect). For the first processing, ultrasonic-assisted degassing is required for 30 minutes to release the dissolved gas in the form of bubbles (reducing the shock wave effect of bubble collapse and noise). The surfactant stock solution is 50-60% octylphenol (as a hydrophobic group, providing lipophilicity for surface activity) and 40-50% polyoxyethylene chain (as a hydrophilic group, providing hydrophilicity, solving solubility and surface activity). The B regulator is an acid salt, and the organic solvent stock solution is 40-50% pure water, 40-50% isopropyl alcohol (reducing the liquid viscosity and increasing the cavitation effect) and 5-10% glycerol (preventing the rapid volatilization of the organic solvent and prolonging the liquid life).

[0027] Step 2: Use solid wax to evenly apply on the upper surface of the ceramic plate, and then bond the crystal to the upper surface of the ceramic plate. After cooling, the bonding is completed. After the bonding is completed, place it on the laser cutting device for cutting;

[0028] The laser cutting is started by power supply, and the original laser beam is generated with the assistance of working gas. The working gas can protect the internal components of the laser and maintain a suitable gas environment for laser generation. Cooling water is used to take away the heat generated by the laser when it is working to prevent its performance from degradation or damage due to overheating. The original laser beam is reflected by a reflector, changing the direction of laser propagation and guiding the laser beam to move in the focusing direction. Finally, the crystal is focused through a laser focusing mirror (to concentrate the energy and improve the cutting ability of the crystal).

[0029] Step 3, placing the cut crystal at the bottom of the ultrasonic peeling equipment processing tank, and then pouring the prepared peeling liquid into the ultrasonic peeling equipment processing tank, and then ultrasonic peeling, the crystal adhered to the ceramic plate is prevented from colliding with the edge and the bottom through the ceramic plate during the placement process, and it can also prevent the crystal from having poor rigidity and being difficult to effectively transmit ultrasonic vibration when the thickness is less than 2000μm, resulting in reduced peeling efficiency;

[0030] The ultrasonic stripping power is 300w, the time is 10mins, and the stripping efficiency when the crystal thickness is less than 2000μm is shortened from the original 5mins to 2mins.

[0031] Step 4: Use thinning equipment to process the crystal and ceramic disk after ultrasonic peeling to complete the entire grinding process.

[0032] Step 5. After processing, place the remaining crystals and the ceramic plate on the upper surface of the heating plate and heat them to melt the solid wax and remove the remaining crystals. Then put the remaining crystals and the ceramic plate into a 50°C anhydrous ethanol solution and ultrasonically clean them for 10-15 minutes. After cleaning, use a dust-free cloth to wipe off any residual impurities on the surface.

[0033] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for improving the ultrasonic stripping efficiency of crystals and avoiding collisions, characterized in that It includes the following steps: S1. Select a ceramic disc according to the crystal size, heat the ceramic disc to 100 °C, and then prepare the solid wax and the ultrasonic stripping liquid; S2. Uniformly apply the solid wax on the upper surface of the ceramic disc, then bond the crystal on the upper surface of the ceramic disc, complete the bonding after cooling, and place it on a laser cutting device for cutting after bonding; S3. Place the cut crystal at the bottom of the processing tank of the ultrasonic stripping equipment, then pour the prepared stripping liquid into the processing tank of the ultrasonic stripping equipment, and then perform ultrasonic stripping; S4. Process the ultrasonically stripped crystal and the ceramic disc with a thinning device to complete the entire grinding process; S5. After processing, place the remaining crystal and the ceramic disc on the upper surface of a heating plate to melt the solid wax and remove the remaining crystal, then put the remaining crystal and the ceramic disc into an absolute ethanol solution for ultrasonic cleaning for 10 - 15 minutes, and use a dust-free cloth to wipe off the residual impurities on the surface.

2. A method for improving the ultrasonic peeling efficiency of crystals and avoiding collisions, characterized in that: In S1, the crystals are divided into 6-inch crystals and 8-inch crystals. Among them, for 6-inch crystals, a ceramic disc of 160×10 is used, and for 8-inch crystals, a ceramic disc of 220×10 is used. The heating of the ceramic disc is by a heating plate.

3. A method for improving the ultrasonic peeling efficiency of crystals and avoiding collisions according to claim 2, characterized in that: The solid wax contains 65% paraffin wax, 15% stearic acid, 15% rosin, and 5% microcrystalline wax. The ultrasonic stripping liquid contains 68.5% basic liquid medium, 1% surfactant stock solution, 0.5% B regulator, and 30% organic solvent stock solution.

4. A method for improving the ultrasonic peeling efficiency of crystals and avoiding collisions, characterized in that: In S2, the laser cutting is started by power supply. Under the assistance of the working gas, an original laser beam is generated, cooled by the action of cooling water, and the original laser beam is reflected by a reflector to change the laser propagation direction, guide the laser beam to travel in the focusing direction, and finally focus the laser beam through a laser focusing lens to cut the crystal.

5. A method for improving the ultrasonic peeling efficiency of crystals and avoiding collisions, characterized in that: In S3, the ultrasonic stripping power is 300 w, the time is 10 mins, and when the crystal thickness < 2000 μm, the stripping efficiency is also shortened from the original 5 mins to 2 mins.

6. A method for improving the ultrasonic peeling efficiency of a crystal and avoiding collision, characterized in that: In S5, the ultrasonic cleaning temperature of the absolute ethanol solution is 50 °C.

7. A method for improving the ultrasonic peeling efficiency of crystals and avoiding collisions, as described in claim 3, characterized in that: The basic liquid medium is pure water, and ultrasonic-assisted degassing for 30 minutes is required for the first processing. The surfactant stock solution is 50 - 60% octylphenol and 40 - 50% polyoxyethylene chain. The B regulator is an acid salt. The organic solvent stock solution is 40 - 50% pure water, 40 - 50% isopropanol, and 5 - 10% glycerol.

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