Ultrasonic diamond scribing device and ultrasonic breaker device

Abstract

To provide a scribing unit that can deepen vertical cracks that occur during scribing when scribe-processing brittle materials etc. as work material, and an ultrasonic breaker that can instantly break (separate) the material after scribing.SOLUTION: Scribing is performed by amplifying vibrations at the cutting edge of a single crystal diamond tool 4 that is attached to the tip of a cone of a highly rigid ultrasonic holder, which has a Langevin type piezoelectric element 2, horn 3, and the cone fixed with an outer cylinder. The work material is fixed to an ultrasonic vibration table equipped with multiple Langevin type piezoelectric elements and a mechanism for vibrating a suction table in the vertical direction, and scribed with the single crystal diamond.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention is a mechanical processing method for cutting glass and various ceramics. Conventionally, a carbide wheel is pressed against the surface of the workpiece, rolling to create a scribe line, causing a crack, and then the indentation load is increased to propagate the secondary crack. This method involves a large load, which can cause distortion due to residual stress during scribing and cutting, damaging the workpiece and resulting in quality problems. By applying ultrasonic vibrations to the tip of the tool or to the workpiece suction table, the load required to draw the scribe line is minimized, promoting the propagation of vertical cracks using ultrasonic waves. This significantly reduces the cutting load, enabling damage-free separation. [Background technology]

[0002] The substrate (DBC) used for power devices is made by directly bonding a copper plate to a ceramic plate, forming a resist using photolithography, and then etching to create an electrode pattern. If a thick copper pattern can be formed in the desired shape, the degree of freedom in pattern design will increase. If screen printing, which has excellent productivity, can be applied, the desired copper film thickness and opening width can be changed for each pattern by using multiple printing masks. This is expected to lead to unique electrode structure designs and reduced mass production costs. Conventional laser scribing has the risk of molten material (spatter) from the laser irradiated area scattering and adhering to the pattern. In addition, thermal diffusion by the laser generates thermal stress between the ceramic and copper electrode. Ultrasonic diamond scribing is expected to reduce these problems. The cutting method for glass and hard, brittle ceramic substrates for power semiconductors and various compound semiconductors is the so-called mechanical scribing method, in which a carbide wheel is applied with a load to the surface of the workpiece to draw a line, and the stress of the scribed line on the surface causes cracks in the workpiece in both horizontal and vertical directions, dividing it. Alternatively, there is the so-called dicing method, in which a thin, doughnut-shaped sintered diamond grinding wheel called a blade (peripheral cutting blade) is rotated at high speed and cuts while spraying water on it. There is also the laser scribing method, in which a laser such as the aforementioned carbon dioxide laser is aimed at the workpiece to continuously drill tiny holes and cut it. However, both methods pose problems that can impair the quality of the substrate from which the workpiece is cut. Conventional mechanical scribing involves applying a load of several newtons to cut the substrate, leaving residual stress damage in the substrate and causing defects in the circuitry on the substrate. Dicing generates chips called kerf loss, which is equal to the thickness of the peripheral cutting edge. Cutting while spraying water poses environmental issues, such as wastewater treatment. Furthermore, spraying water can affect the electrical circuits on the substrate. Laser scribing suffers from the problem of low yields, as the high-temperature laser causes molten material to adhere to the substrate and nearby electrodes, which cannot be removed even by cleaning, resulting in defects being discovered at the chip packaging stage. Therefore, the ultrasonically assisted diamond scriber proposed here offers a solution to these problems, and there is great hope for its practical application. Summary of the Invention [Problem to be solved by the invention]

[0002] The problem that the present invention aims to solve is to provide a scribing unit and device that utilizes ultrasonic vibrations in the vertical direction with a single crystal diamond tool to scribe brittle materials and other workpieces, thereby making it possible to generate deeper vertical cracks required for dividing the workpiece, and an ultrasonic breaker that utilizes bending vibrations. [Means for solving the problem]

[0003] The present invention was made to solve the above-mentioned problems, and is an apparatus consisting of a unit and control system comprising a transmitter, a Langevin-type piezoelectric element, a horn, a load cell, a sensor for a contact-type surface profile scanner, a single-crystal diamond with a shaft, a single-crystal diamond wheel, and an ultrasonic vibration adsorption table. The ultrasonic vibration generated by the Langevin-type piezoelectric element is amplified by the horn, and the amplified ultrasonic vibration is applied to a single-crystal diamond tool attached to the tip of the horn to scribe. The ultrasonic diamond scriber unit and apparatus apply ultrasonic vibration to the workpiece (material to be cut) using the ultrasonic vibration table. [Effects of the Invention]

[0004] The scribe head of the present invention can extend vertical cracks that affect separation after scribing by approximately 70% more than scribing using a diamond tool without the aid of ultrasonic vibration. [Brief explanation of the drawings]

[0005] [Figure 1] Transmitter and vibration unit diagram (scribe head) [Figure 2] Ultrasonic vibration table and suction table DETAILED DESCRIPTION OF THE INVENTION

[0006] As shown in the figure, the scribing head of this embodiment is composed of a transmitter 1, a Langevin-type piezoelectric element 2, a horn 3, a single-crystal diamond tool 4, and a load cell 6. The transmitter 1 applies a voltage to the Langevin-type piezoelectric element 2, generating ultrasonic vibrations. The generated ultrasonic vibrations are amplified by the horn 3, which is joined to the Langevin-type piezoelectric element 2, and transmitted to the diamond tool 4 attached to the tip of the horn. The tip of the single-crystal diamond tool 4, to which ultrasonic vibrations have been applied, is brought into contact with the top surface of the workpiece 5, and the load cell detects the load applied to press the tool into the uneven surface of the workpiece while applying ultrasonic vibrations in the vertical direction. The single-crystal diamond tool 4 is then moved horizontally while feedback-controlled in the Z-axis to scribe. [Example]

[0007] As shown in this diagram, after the workpiece is fixed on the ultrasonic vibration suction table, the tool tip is lowered to the position of the top surface of the workpiece. The Z coordinate of the uneven surface at the separation position is scanned by a non-contact sensor, and the cutting depth is set from that position, and the cutting depth and XY movement of the scriber head are automatically controlled by a program. [Explanation of symbols]

[0008] 1 transmitter 2. Langevin type piezoelectric element 3 Horns 4 Single crystal diamond tools 5 Work material 6 load cells 7. Vacuum table 8 Ultrasonic Breaker 9 ultrasonic vibration table

Claims

1. An ultrasonic diamond scriber tool unit that applies ultrasonic longitudinal vibrations to a single crystal diamond with an attached shaft and a tool tip formed into a conical or pyramidal shape, or to a single crystal diamond wheel, to scribe straight lines and quadratic curves on the surface of workpieces such as glass, ceramics, and compound semiconductor materials (various wafers, various substrates, electrode-formed products), and promote the extension of microcracks in the vertical direction.

2. An ultrasonic vibration table equipped with a Langevin type piezoelectric element generates vertical vibrations on a vibration plate (suction table), which transmits mechanical vibrations to the workpiece fixed to the suction table, causing resonance, reducing tool machining with vertical vibrations and promoting vertical extension of cracks with ultrasonic vibrations.

3. An ultrasonic vibration breaker that generates bending vibrations on a vibration plate (suction table) using a suction table equipped with a Langevin type piezoelectric element, which transmits mechanical vibrations to the workpiece fixed to the suction table, causing it to resonate and break and separate due to the bending moment.

4. In order to scribe uneven surfaces of workpieces that are not flat, this ultrasonic diamond scrubber device is equipped with a laser displacement meter that uses a non-contact sensor to scan the unevenness of the workpiece surface, a CCD camera that detects the alignment of the workpiece (reference hole and outer periphery), a load cell to detect the position of the unevenness on the workpiece surface, the tool tip comes into contact with the workpiece, detects the position where the load is applied, and tracks the load at a constant indentation load, providing Z-axis position control.

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