Wafer splitting machine
The wafer splitting apparatus addresses large apparatus size and stress-related wafer damage by using an ultrasonic horn for uniform stress application, ensuring stable and low-stress splitting with controlled cleavage planes.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- NAKAMURATOME SEIMITSU IND
- Filing Date
- 2024-12-10
- Publication Date
- 2026-06-22
AI Technical Summary
Existing wafer dicing methods face challenges with large apparatus size, stress concentration leading to wafer damage, and instability in the cleavage plane due to wet peeling methods and non-controlled stress generation.
A compact wafer splitting apparatus utilizing an ultrasonic horn to apply ultrasonic vibrations from the upper surface of a wafer material with a preliminary fracture layer, leveraging crystallographic properties for cleavage and employing temporary adhesion to ensure uniform stress application.
The apparatus achieves stable and low-stress wafer splitting with uniform cleavage planes, avoiding wet peeling and promoting fracture completion even at unirradiated edges, while being compact and compatible with other dicing methods.
Smart Images
Figure 2026100925000001_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a wafer dicing apparatus used in the manufacturing process of wafers for semiconductor products.
Background Art
[0002] As semiconductor materials, single-crystal silicon or single-crystal materials such as silicon carbide, gallium nitride, and sapphire are used. As one of the methods for manufacturing wafers made of these semiconductor materials, a laser scribing method is known. In the laser scribing method, a laser beam with its focus narrowed to a predetermined depth is dot-irradiated in the XY direction from the surface side of an ingot or a thick wafer block (hereinafter referred to as a wafer material) that serves as a raw material for manufacturing a wafer, thereby forming a preliminary dicing layer with numerous cleavages generally in the XY direction. After that, the wafer is diced by applying a mechanical peeling stress in the dicing direction. [[ID=1-eighteen]]Thus, in order to apply a large peeling stress between the wafer and the wafer material, the upper surface of the wafer and the wafer material are each mechanically fixed, and a large mutual pulling force or an impact force is applied. In this case, fixing means for the wafer and the wafer material are required respectively, and the dicing apparatus becomes large-sized. In addition, there is also a technical problem that when the tensile load applied to the wafer is concentrated in part, the wafer is likely to be damaged.
[0003] <For example, Patent Documents 1 to 3 disclose a peeling apparatus that oscillates ultrasonic waves in water and peels an ingot while sucking and holding a wafer. <However, the technique disclosed in the publication cannot control the direction of stress generation due to ultrasonic vibration because it either applies stimulation to the preliminary dicing layer of the wafer with ultrasonic waves or oscillates ultrasonic waves in water. Also, since it is a wet peeling method, post-treatment such as drying is required thereafter.
Prior Art Documents
Patent Documents
[0004] [Patent Document 1] Japanese Patent Publication No. 2019-096751 [Patent Document 2] Japanese Patent Publication No. 2019-102513 [Patent Document 3] Japanese Patent Publication No. 2019-102676 [Overview of the Initiative] [Problems that the invention aims to solve]
[0005] The present invention aims to provide a wafer splitting apparatus that is compact, can split wafers with low stress, and has stable quality for the split surface. [Means for solving the problem]
[0006] The wafer splitting apparatus according to the present invention is a wafer splitting apparatus for splitting a wafer from a wafer material on which a preliminary split layer has been formed by a laser slicing method, and is characterized by having a stage on which the wafer material is placed and an ultrasonic horn for applying ultrasonic vibrations from the upper surface side of the wafer material placed on the stage.
[0007] Here, forming a preliminary fracture layer by laser slicing means that semiconductor materials made of single crystals have the property of cleaving along specific crystallographic lattice planes. By utilizing this property, a large number of cleavage points can be formed by irradiating and scanning the surface of a wafer material, such as an ingot or wafer block, with laser light focused to a predetermined depth. In this specification, wafer material in this state is referred to as wafer material with a preliminary fracture layer formed on it.
[0008] Furthermore, an ultrasonic horn is a device used to apply ultrasonic vibrations to a wafer material by placing its front surface on the top surface of the wafer material.
[0009] In this invention, a wafer material is placed on a stage, and ultrasonic vibrations are applied from the upper surface of the wafer material. Therefore, to prevent the stage from resonating with the ultrasonic horn, it is preferable that the natural frequency of the stage differs from the frequency of the ultrasonic horn. This makes it easier for the amplitude stress of ultrasonic vibrations to be applied to the wafer. Here, the natural frequency of the stage may be shifted to either the higher or lower frequency side compared to the frequency of the ultrasonic horn.
[0010] In the present invention, it is preferable that the ultrasonic vibration is a longitudinal wave that applies uniform vibration stress to the entire surface of the preliminary fracture layer of the wafer material. Here, if there is a longitudinal wave vibration mode that vibrates perpendicular to the plane of the fault, it may be a superimposed mode that includes other vibration modes.
[0011] In the present invention, the vibration stress applied to the preliminary fracture layer is the repeated application of an impact load by ultrasonic vibration at an extremely short period, but it is more preferable that tensile stress in the delamination direction is generated. Therefore, the front surface of the ultrasonic horn and the top surface of the wafer material may be simply bonded together. Here, "simple adhesion" refers to temporary bonding using adhesives such as adhesive tape or adhesive sheets, or even adhesive waxes, that can be easily removed after vibration with ultrasound. [Effects of the Invention]
[0012] The wafer cleaving apparatus according to the present invention is compact because it does not use the wet method described in Patent Documents 1 to 3, and the cleavage plane is stabilized because vibration stress is repeatedly applied perpendicular to the plane of the preliminary cleavage layer with a short period due to ultrasonic vibration. Furthermore, when forming a preliminary fracture layer on a wafer material by laser irradiation, it is often difficult to irradiate the outer edge of the wafer material with the laser, and connections remain at crystal planes where fracture initiation points have not yet been formed. However, even in such cases, cleavage can be advanced by the vibrational stress caused by ultrasound, allowing the wafer to fracture. The wafer dicing apparatus according to the present invention aims to promote the cleavage of the dicing layer by vibration stress caused by ultrasonic waves, and can also be combined with other types of dicing apparatuses.
Brief Description of the Drawings
[0013] [Figure 1] Shows a configuration example of the wafer dicing apparatus according to the present invention. [Figure 2] Shows a photographic example of a wafer cut surface. [Figure 3] (a) shows an example of the shape of an ultrasonic horn, and (b) shows an example of a simulation analysis of the vibration mode. [Figure 4] (a) shows an example of the shape of another ultrasonic horn, and (b) shows an example of a simulation analysis of its vibration mode.
Modes for Carrying Out the Invention
[0014] A configuration example of the wafer dicing apparatus according to the present invention will be described below based on the drawings. FIG. 1 schematically shows the components. It consists of placing a wafer material W on a stage 12 and an ultrasonic horn 11 arranged on its upper surface. As the wafer dicing apparatus, it has a means for loading the wafer material W (not shown), a means for controlling the raising and lowering of the ultrasonic horn, and a means for applying ultrasonic vibration to the wafer material W and taking out the wafer P after forming the dicing layer 13. The oscillation frequency of the ultrasonic wave is preferably in the range of 16 to 24 kH Z and the total amplitude in the vertical direction of the front surface of the ultrasonic horn is preferably 7 μm or more. FIG. 2 shows a photographic example of a cut surface obtained by dicing and manufacturing a wafer P from a wafer material using the wafer apparatus according to the present invention. It can be seen that it is a stable cut surface.
[0015] The ultrasonic horn used in the present invention preferably has vibration stress uniformly applied to the front surface of the preliminary dicing layer. Therefore, it was verified by simulation analysis whether the front surface of the ultrasonic horn vibrates uniformly. The simulation analysis software used was "CATIA V5". Figure 3(a) shows the connection point 11a between the ultrasonic horn 11 and the ultrasonic oscillation source. The connector 11a is configured as a stepped horn to amplify the amplitude and smooth the wavefront. By forming a predetermined slit 11b on the side of the ultrasonic horn 11, a uniform amplitude appeared on the front surface of the ultrasonic horn 11 in the simulation analysis, as shown in Figure 3(b). Furthermore, by making the shape of the ultrasonic horn 11 a drum shape, as shown in Figure 4(a), a uniform amplitude is obtained on the front surface, as shown in the simulation analysis in Figure 4(b). In this invention, the present invention is not limited to this embodiment, as long as a uniform amplitude can be produced on the front surface of the ultrasonic horn 11. [Explanation of Symbols]
[0016] 11. Ultrasonic horn 12 stages 13 Fault W wafer material P wafer
Claims
1. A wafer splitting apparatus for splitting a wafer from a wafer material on which a preliminary split layer has been formed by a laser slicing method, A wafer splitting apparatus characterized by having a stage on which wafer material is placed, and an ultrasonic horn for applying ultrasonic vibrations from the upper surface of the wafer material placed on the stage.
2. The wafer splitting apparatus according to claim 1, characterized in that the natural frequency of the stage is different from the frequency of the ultrasonic horn.
3. The wafer splitting apparatus according to claim 2, characterized in that the ultrasonic vibration is a longitudinal wave that applies uniform vibration stress to the entire surface of the preliminary split layer of the wafer material.
4. The wafer splitting apparatus according to any one of claims 1 to 3, characterized in that the front surface of the ultrasonic horn and the upper surface of the wafer material are simply bonded together.