Immersion type free abrasive particle auxiliary fretsaw cutting machining device and method

Abstract

The invention provides an immersion liquid type free abrasive particle auxiliary fretsaw cutting machining device and method, and belongs to the technical field of monocrystalline silicon cutting. The immersion liquid type free abrasive particle auxiliary fretsaw cutting machining device comprises a machine tool base, a diamond fretsaw unit A, a saw wire feeding unit B, a workpiece rotating unit C, a water tank unit D and a testing unit E. The diamond fretsaw unit A comprises a wire cylinder surrounding a saw wire; the saw wire is matched with the wire cylinder through the tensioning wheel and the guide wheel to form a ring, and the water tank unit D comprises a water tank and cutting fluid which is contained in the water tank and contains diamond free abrasive particles. The wire cylinder is driven by the motor to rotate, and meanwhile, the unit A moves downwards along the z axis under the driving of the rack. The monocrystalline silicon rod enters the water tank after rotating and is cut through reciprocating motion of the saw wire, and the testing unit E keeps working and records data in the cutting process. The immersion type free abrasive particles are used for assisting the fretsaw in cutting for the first time. The surface quality of a workpiece can be improved, the sawing force borne by the sawing wire is reduced, the cutting temperature is lowered, and therefore the service life of the sawing wire is prolonged.

Description

Technical Field

[0001] The invention belongs to the technical field of single crystal silicon cutting, and in particular relates to an immersion-type free abrasive grain-assisted wire saw cutting processing device and method. Background Art

[0002] Integrated circuits are not only the cornerstone of modern scientific and technological development, but also an important force in promoting social progress. The development of integrated circuits has enabled electronic devices to achieve more powerful computing capabilities in a smaller volume, thus promoting the rapid development of scientific and technological products such as computers and smart phones. With the advancement of science and technology, fields such as chips have increasingly higher requirements for the purity, flatness, consistency and stability of semiconductors. Monocrystalline silicon is an important semiconductor material whose crystal structure is a perfect lattice composed of silicon atoms. This highly ordered structure gives monocrystalline silicon excellent electrical properties, making it one of the main materials in the semiconductor industry, and plays an important role in fields such as integrated circuits and solar energy. However, monocrystalline silicon materials have the characteristics of high hardness, high brittleness, and easy collapse, which makes the processing of monocrystalline silicon very difficult.

[0003] Wire sawing of single crystal silicon is widely used in semiconductor processing. This process uses a wire saw to cut single crystal silicon rods into single crystal silicon slices. The processing principle is as follows: Figure 1 As shown. The saw wire is wound and tensioned by a tensioning wheel. During the processing, the wire is retracted and released by the winding wheel to make the saw wire reciprocate, thereby driving the abrasive to cut the workpiece. The workpiece is fed in a direction perpendicular to the saw wire to achieve the cutting of the single crystal silicon rod. Wire saw slicing technology can be divided into free abrasive wire saw cutting technology and consolidated diamond abrasive wire saw cutting technology. With the improvement of processing requirements, the single process of using only consolidated diamond wire saw cutting can no longer meet the requirements of improving the surface quality of the workpiece and processing efficiency. Various composite wire saw cutting processes have emerged.

[0004] In the prior art, scholars have conducted relevant research on the composite processing of fixed free abrasive particles. Figure 2 As shown in the figure, this process also uses free abrasives and fixed abrasives to perform wire saw cutting of single crystal silicon wafers. A nozzle is used to spray cutting fluid containing free abrasives onto the saw wire of the fixed abrasive wire saw. For this purpose, a multi-stage fixed abrasive wire saw is designed as shown in the figure.

[0005] However, the current traditional wire saw cutting and free abrasive assisted wire saw cutting methods still have problems such as poor processing quality, high cutting temperature, and difficulty in chip removal during processing resulting in high sawing force. Summary of the invention

[0006] The object of the present invention is to provide an immersion-type free abrasive grain-assisted wire saw cutting processing device, characterized in that it comprises a diamond wire saw unit, a wire feeding unit for vertically moving the diamond wire saw unit, a workpiece rotating unit for driving the workpiece to rotate and move forward and backward, and a water tank unit;

[0007] The water tank unit comprises a water tank, wherein the water tank is filled with a cutting fluid comprising free diamond abrasive particles;

[0008] The diamond wire saw unit comprises a wire drum driven to rotate by a machine tool motor, and a saw wire for cutting a workpiece is surrounded by the outer circumference of the wire drum;

[0009] The workpiece rotating unit is connected to the workpiece and drives the workpiece to perform a rotating motion.

[0010] Furthermore, the diamond wire saw unit and the wire feeding unit are connected as part of a machine tool and controlled by the machine tool. The wire is rotated by the diamond wire saw unit and moved downward into the water tank through the wire feeding unit to complete the cutting of the workpiece.

[0011] Furthermore, the diamond wire saw unit also includes a tensioning wheel for controlling the tensioning force and a driving wheel for changing the direction of the saw wire. The saw wire is formed into a ring shape by the wire drum, the tensioning wheel and the driving wheel, and reciprocates through the rotation of the wire drum.

[0012] Furthermore, it also includes a testing unit for recording the sawing force, the testing unit includes a dynamometer, a charge amplifier, a data collector and a computer connected in sequence, and the dynamometer is connected to the workpiece to realize the detection.

[0013] A liquid-immersion free abrasive assisted wire saw cutting processing method, using a liquid-immersion free abrasive assisted wire saw cutting processing device, specifically comprising the following steps:

[0014] Step 1: The wire is subjected to a constant tension F applied by the tension wheel T , so that the saw wire is always in a taut state;

[0015] Step 2: The wire drum is driven by the motor to rotate, and the saw wire moves at a linear speed v s Make reciprocating motion along the x-axis in the processing area;

[0016] Step 3: The wire feeding unit drives the wire saw, wire drum, tension wheel and main wheel at a linear speed v w Feeding motion is performed vertically downward along the z-axis;

[0017] Step 4: The single crystal silicon rod rotates around the origin driven by the main shaft at a speed of n w ;

[0018] Step 5: Place the single crystal silicon rod into the water tank through the preset hole at the rear side of the water tank, and add cutting fluid mixed with free diamond abrasive particles into the water tank;

[0019] Step 6: Cutting is performed. During the cutting process, the dynamometer keeps working, and transmits the signal to the computer through the charge amplifier and the data collector to record the data;

[0020] Step 7: After completing the cutting of a single crystal silicon wafer, the single crystal silicon rod is moved toward the water tank through the machine tool adjustment to cut the next single crystal silicon wafer.

[0021] Compared with the prior art, the beneficial effects of the present invention are mainly reflected in: providing an immersion-type free abrasive auxiliary wire saw cutting device and method, through which the surface quality of the workpiece can be improved, the sawing force on the saw wire can be reduced, and the cutting temperature can be reduced, thereby increasing the service life of the saw wire. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of wire saw machine cutting single crystal silicon.

[0023] Figure 2 This is the cutting principle diagram of the bonded-free abrasive composite wire saw.

[0024] Figure 3 This is the principle diagram of the immersion free abrasive assisted wire saw cutting process.

[0025] Figure 4 This is a schematic diagram of the principle of the immersion-type free abrasive-assisted wire saw cutting process of the present invention.

[0026] Figure 5 This is a schematic diagram of the processing area of ​​single crystal silicon cutting using an immersion-type free abrasive-assisted wire saw according to the present invention. DETAILED DESCRIPTION

[0027] The following will be described in more detail with reference to schematic diagrams of an immersion-type free abrasive-assisted wire saw cutting processing device and method of the present invention, wherein a preferred embodiment of the present invention is shown. It should be understood that those skilled in the art can modify the present invention described herein while still achieving the beneficial effects of the present invention. Therefore, the following description should be understood as being widely known to those skilled in the art and not as a limitation to the present invention.

[0028] like Figure 3 and 4 As shown, an immersion-type free abrasive-assisted wire saw cutting processing device is used to cut single crystal silicon. The device consists of a machine tool base (not shown in the figure), a diamond wire saw unit A, a wire feeding unit B (frame), a rotary unit C (rotary table), a water tank unit D and a testing unit E.

[0029] like Figure 1 As shown, the diamond wire saw unit A and the wire feeding unit B are part of the machine tool. In the diamond wire saw unit A, the wire 1 forms a ring around the wire tube 2, the first tensioning wheel 3 and the second tensioning wheel 4, the first main wheel 5 and the second main wheel 6, which all move up and down with the wire feeding unit B. The tension of the wire can be adjusted by a specific device and / or tensioning wheel of the machine tool. The function of the first main wheel 5 and the second main wheel 6 is to change the direction of the wire. The rotary table is fixed on the lead screw, and the single crystal silicon rod can be moved by controlling the lead screw.

[0030] The workpiece is a cylindrical single crystal silicon rod 7. During processing, the saw wire 1 is subjected to a constant tensioning force F applied by the tensioning wheel. T This keeps the saw wire 1 in a taut state. The wire drum 2 is driven by the motor to rotate, so that the saw wire 1 moves at a linear speed v s The processing area makes reciprocating motion along the x-axis direction. At the same time, driven by the frame, the saw wire 1, the wire drum 2, the tension wheel and the main wheel move at a linear speed v w The single crystal silicon rod 7 is driven by the rotary table to rotate around the origin at a speed of n. w The single crystal silicon rod 7 and the wire saw near the single crystal silicon rod 7 are immersed in a water tank 8 containing a cutting fluid with free diamond abrasive particles.

[0031] The sawing force test unit E is composed of a Kistler dynamometer 9, a charge amplifier and a data acquisition device 10 and a computer 11. They are connected in sequence using a data line.

[0032] An immersion-type free abrasive assisted wire saw cutting process, using the above processing device, the specific use method and principle are as follows:

[0033] The single crystal silicon rod 7 is fixed on the rotary table to make it rotate. The saw wire 1 is subjected to a constant tensioning force F applied by the tensioning wheel. T This keeps the saw wire 1 in a taut state. The wire drum 2 is driven by the motor to rotate, so that the saw wire 1 moves at a linear speed v s The processing area makes reciprocating motion along the x-axis direction. At the same time, driven by the frame, the saw wire 1, the wire drum 2, the tension wheel and the main wheel move at a linear speed v w The single crystal silicon rod 7 is driven by the main shaft to rotate around the origin at a speed of n. w The single crystal silicon rod 7 is passed through the back side of the water tank 8 and enters the water tank 8, and a cutting fluid mixed with free diamond abrasive particles is added to the water tank 8. During the cutting process, the Kistler dynamometer 9 keeps working, and transmits the signal to the computer 11 through the charge amplifier and the data acquisition device 10 and records the data. After completing the cutting of a single crystal silicon wafer, the machine tool is adjusted to move the single crystal silicon rod 7 to cut the next single crystal silicon wafer.

[0034] The principle of fluid dynamic pressure effect

[0035] refer to Figure 2 and Figure 5 There are four conditions for the fluid dynamic pressure effect: the friction surface has a convergent wedge; the journal has sufficient speed; the lubricating oil has an appropriate viscosity; and the external load is less than the limit that the minimum oil film can withstand. Figure 5 As shown, in the process of immersion-type free abrasive assisted wire saw cutting, the workpiece being cut is a cylindrical single crystal silicon rod 7, and the saw wire 1 is tightly attached to the workpiece due to the preload. Since the entire cutting area is immersed in the cutting fluid containing fine diamond abrasive particles, the grinding fluid at the entrance of the cutting area will be pushed into the cutting gap. The impact force of the cutting fluid will cause a radial gap to form between the saw wire 1 and the workpiece material, thus forming a convergent wedge. At this time, the conditions for the fluid dynamic pressure effect to occur are met in the fluid dynamic pressure zone shown in the figure. When the fluid dynamic pressure is less than the radial load on the saw wire 1, the radial gap between the saw wire 1 and the workpiece will decrease, and the thickness of the oil film will decrease accordingly. At this time, the fluid dynamic pressure will increase until the saw wire 1 reaches radial load balance.

[0036] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any technician in the relevant technical field, without departing from the scope of the technical solution of the present invention, makes any form of equivalent replacement or modification to the technical solution and technical content disclosed in the present invention, which does not depart from the content of the technical solution of the present invention and still falls within the protection scope of the present invention.

Claims

1. An immersion-type free abrasive assisted wire saw cutting processing device, characterized in that: It includes a diamond wire saw unit, a wire feeding unit for vertically moving the diamond wire saw unit, a workpiece rotating unit for driving the workpiece to rotate and move forward and backward, and a water tank unit; The water tank unit comprises a water tank, wherein the water tank is filled with a cutting fluid comprising free diamond abrasive particles; The diamond wire saw unit comprises a wire drum driven to rotate by a machine tool motor, and a saw wire for cutting a workpiece is surrounded by the outer circumference of the wire drum; The workpiece rotating unit is connected to the workpiece and drives the workpiece seat to rotate.

2. The immersion type free abrasive assisted wire saw cutting processing device according to claim 1, characterized in that: The diamond wire saw unit and the wire feeding unit are connected as part of the machine tool and are controlled by the machine tool. The wire is rotated by the diamond wire saw unit and moved downward into the water tank through the wire feeding unit to complete the cutting of the workpiece.

3. The immersion type free abrasive assisted wire saw cutting processing device according to claim 1, characterized in that: The diamond wire saw unit further comprises a tensioning wheel for controlling the tensioning force and a driving wheel for changing the direction of the saw wire. The saw wire is formed into a ring through the wire drum, the tensioning wheel and the driving wheel, and reciprocates through the rotation of the wire drum.

4. The immersion type free abrasive assisted wire saw cutting processing device according to claim 1, characterized in that: It also includes a testing unit for recording the sawing force, the testing unit includes a dynamometer, a charge amplifier, a data collector and a computer connected in sequence, and the dynamometer is connected to the workpiece to realize detection.

5. A method for cutting with a liquid-immersion free abrasive assisted wire saw, using the liquid-immersion free abrasive assisted wire saw cutting device according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1: The wire is subjected to a constant tension F exerted by the tension wheel T , so that the saw wire is always in a taut state; S2: The wire drum is driven by the motor to rotate, and the wire is sawed at a linear speed v s Make reciprocating motion along the x-axis in the processing area; S3: The wire feeding unit drives the wire saw, wire drum, tension wheel and main wheel at a linear speed v w Feeding motion is performed vertically downward along the z-axis; S4: The single crystal silicon rod rotates around the origin driven by the main shaft at a speed of n w ; S5: placing the single crystal silicon rod into the water tank through a preset hole at the rear side of the water tank, and adding cutting fluid mixed with free diamond abrasive particles into the water tank; S6: Cutting is performed. During the cutting process, the dynamometer keeps working, and the signal is transmitted to the computer through the charge amplifier and the data collector to record the data; S7: After completing the cutting of a single crystal silicon wafer, the single crystal silicon rod is moved toward the water tank through the machine tool adjustment to cut the next single crystal silicon wafer.

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