RU2494852C1 - Method of solid surface machining - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to surface processing, particularly, for preparation of plate surface and can be used in microelectronics, for example, in machining superhard material substrates for epitaxy processes. Motions of tool and solid are regular cyclic and periodical. Here, arbitrary points at the surfaces of tool and solid circumscribe transcendental curves. Relationship between the frequencies of tool and solid cyclic motions is larger than unity not equal thereto.

EFFECT: higher surface finish.

5 cl, 6 dwg

Description

The invention relates to the field of processing solids, mainly for preparing their surface. A method of treating a solid surface can be used, for example, for treating substrates of superhard materials for carrying out epitaxy processes.

A known method of one-sided polishing of flat surfaces [1], including the processing of flat surfaces of silicon wafers of large diameter. The latter are mounted with the possibility of rotation around their axes and the axis of the spindle, while being eccentric relative to the axis of rotation of the tool.

The disadvantage of this method is that the tool maintains the constancy of the trajectories of the grains of the abrasive, which affects the quality of the polished surface.

There is also a method of processing flat surfaces [2], which consists in the relative movement of the tool and the object along the epicycloid, while the object and the tool are informed of additional relative movement along the lemniscate. This method is selected as a prototype of the proposed solution.

The first disadvantage of this method is that the movement along the lemniscate is a linear movement over a given surface area. In this case, the probability of repeating the trajectories of the grains of the abrasive tool remains, which leads to a deterioration in the quality of the treated surface of the object.

The second disadvantage is associated with the inability to process surface areas more than a given area of the lemniscate. In this way, it is impossible to qualitatively process round plates of semiconductor materials in the form of an object, intended, for example, for epitaxy, which reduces the functionality of the method.

The technical result of the proposed invention consists in the non-repeatability of the trajectories of the movement of the grains of the abrasive tool on the treated surface of the object, which improves the quality of polishing the surface. In this case, surface polishing is carried out over the entire area of the processed object, which increases the functionality of the method.

The specified technical result is achieved by the fact that in the method of processing the surface of a solid body, including the mutual movement of the tool and the object, arbitrary points on the surface of the tool and the object describe transcendental curves. The irregularity of the trajectories of the movement of the grains of the abrasive tool on the surface of the object is achieved by the fact that the ratio of the frequencies of movement of the tool and the object is greater than unity and not equal to an integer.

There is an option in which the movement of arbitrary points on the surface of the tool and the object is set by different trajectories of cycloidal curves, while the types of trajectories of cycloidal curves are periodically changed.

There is also an option in which a solution of a surface-active substance with an ultrafine abrasive is added to the contact area of the tool with the object, while the pressure of the tool on the object is regularly changed periodically.

There is an option in which ultrasonic vibrations are additionally applied to the instrument and the object, while the ratio of the frequencies of these vibrations is not equal to an integer.

There is a variant in which the joint change of the cycloidal curves of the tool and the object is additionally set algorithmically, while the ratio of the frequencies of movement of the tool and the object is greater than one and is not equal to an integer.

Figure 1 shows a General view of a device for implementing the proposed method.

Figure 2 shows the image of the processed surface of the diamond plate, as a result of using the proposed processing method.

Figure 3 shows an image of a diamond plate. A dark circle marks a selected, arbitrary surface area.

Figure 4 shows the image of the trajectory of an elongated epitrochoid.

Figure 5 shows the image of the trajectory of the epicycloid.

Figure 6 shows an image of a hypocycloid.

The device contains a base 1, with the actuating elements of the object and the actuating elements of the tool fixed to it (Fig. 1).

The executive elements of the object include: the holder of the object 2, the object 3, the first device for generating ultrasonic vibrations 4, the first rotation drive system 5 of the object 3, the first cyclic movement mechanism 6 of the object 3, the first drive system of the cyclic movement mechanism 7 of the object 3.

The executive elements of the object are fixed on the platform 8, coupled with a system of reciprocating movement 9 parallel to the plane of the tool 11 along the guides 10.

Actuator elements of the tool include: tool 11, a second device for generating ultrasonic vibrations 12, a second rotation drive system 14 of the tool 11, a second cyclic movement mechanism 13 of the tool 11, a second drive system of the cyclic movement mechanism 15 of the tool 11, a pressure unit 16 of the tool 11 on the object 3.

The Executive elements of the tool are fixed on the platform 17, which provides the supply of the tool 11 to the object 3.

A device for supplying a solution of 19 surfactant to the contact area between the tool 11 and object 3 is coupled to the base 1 by means of an arm 18. A detailed embodiment of the device for supplying a solution for processing is described in [3].

The first device for generating ultrasonic vibrations 4 of the object 3 and the second device for generating ultrasonic vibrations 12 of the tool 11 are provided with the following modes of generating ultrasonic vibrations. The detailed implementation of the device is reflected, for example, in [4, 5].

The pressure block 16 of the tool 11 on the object 3 provides the following pressure of the tool 11 on the object 3 with a certain periodicity in time, depending on the type of interaction paths of the cycloidal curves of the tool 11 and the object 3.

The method of surface treatment of object 3 is implemented by the device as follows on the example of processing diamond plates for the needs of microelectronics.

A diamond plate (object 3), for example, with a size of 3.3 × 3 × 0.3 mm, is fixed symmetrically with respect to the 0-0 axis on the surface of the holder of object 2, for example, using the Boniceram CC6 specialized ceramic adhesive, manufactured by Nicolectronix, Israel.

On the device, the holder of the object 2, together with the first rotation drive system 5, having an axis of rotation 0-0, is located on the first mechanism of cyclic movement 6 eccentrically relative to its axis 0 ₁ -0 ₁ . The distance between the axis of rotation of the holder of the object 2 (0-0) and the axis of rotation of the first mechanism of cyclic movement 6 (0 ₁ -0 ₁ ) is, for example, in this case r ₁ ~ 3.5 mm.

On the device, the tool 11, for example, in this case ⌀ 40 mm together with the second rotation drive system 14 having an axis of rotation 0 ₂ -0 _2, is located on the second cyclic movement mechanism 13 eccentrically relative to its axis 0 ₂ -0 ₂ . The distance between the axis of rotation of the tool 11 (0 ₂ -0 ₂ ) and the axis of rotation of the second mechanism of cyclic movement 13 (0 ₃ -0 ₃ ) is, for example, in this case R ~ 7 mm.

As an example of the movement of an object along the trajectory of a cycloidal curve, we cite the movement of a marked arbitrary region (region ⌀ ~ 0.4 ÷ 0.6 mm) on the surface of a diamond plate (marked by a dark circle in Fig. 3) placed on the holder of object 2.

The object simultaneously rotates with respect to the movable axis (0-0) of rotation of the holder of the object 2 and translates in a circle with respect to the fixed axis (0 ₁ -0 ₁ ) of rotation of the first mechanism of cyclic movement 6.

In this case, the movement of the object can be defined as the movement of one moving circle with a radius r ₂ ~ 1.5 mm, where r ₂ is the distance from the center of symmetry (rotation axis 0-0) of the diamond plate glued on the holder of object 2 (object 3) to the marked dark area of figure 3. This moving circle rolls along another fixed circle with a radius r ₁ = 3.5 mm and an axis of rotation (0 ₁ -0 ₁ ).

As a result, the marked area on the surface of the object 3 makes a movement described by the cycloidal curve, as the trajectory of an elongated epitrochoid (figure 4).

The tool 11 simultaneously performs a rotational movement relative to the movable axis (0 ₂ -0 ₂ ) of rotation of the tool 11 and a translational motion relative to the fixed axis of rotation (0 ₃ -0 ₃ ) of the second cyclic movement mechanism 13.

In this case, the movement of the object can be considered as movement in a circle with a radius r ₁ around the axis (0 ₁ -0 ₁ ), and the movement of the tool as the movement of grains of abrasive in a circle with a radius R around the axis (0 ₃ -0 ₃ ).

The position of the object on the surface of the tool is set by the movement parameters of the platform 8.

As an example, platform 8 is in a position where the joint movement of object 3 and tool 11 should be considered as the movement of one circle with radius r ₁ rolling along another circle with radius R. As a result of this interaction, the type of trajectory of the cycloidal curve that an arbitrary point on circles with a radius r ₁ relative to the movement of abrasive grains located on a circle with a radius R, will be determined as an epicycloid (figure 5).

With the position of the platform 8, when the joint movement of object 3 and tool 11 should be considered as the movement of one circle with a radius r ₁ rolling inside another circle with a radius R, then the type of trajectory of the cycloidal curve, which describes an arbitrary point on a circle with a radius r ₁ relative to the movement of grains abrasive, located on a circle with a radius R, will be defined as a hypocycloid (Fig.6).

The frequency of cyclic movement of the object 3 is usually set in the range of 1 ÷ 20 Hz. The magnitude and direction of rotation of the object 3 is set within 5 ÷ 50 sec ^-1 .

Tool 11 performs cyclic movements using the second mechanism 13. The frequency of these movements is set, for example, in the range of 15 ÷ 30 Hz. The magnitude and direction of rotation of the tool 11 is set, for example, in the range of 100 ÷ 500 sec ^-1 .

During processing, changing the position of the object on the plane of the tool using the platform 8; the magnitude and direction of the speed of rotation and / or movement of the object 3 and / or tool 11 is the main technological algorithm that allows you to change the types of trajectories and the nature of the interaction of the cycloidal curves of the tool 11 and object 3 [6]. In this case, the ratio of the frequencies of the cyclic movement of the tool 11 and the object 3 should be greater than one and not equal to an integer.

To ensure effective processing of the entire surface of the object 3, the holder of the object 2 and the tool 11 make cyclic movements relative to each other in an area that does not extend beyond the surface of the working tool.

For example, in this variant of processing the object, the diameter of the tool is ~ 40 mm, the magnitude of the eccentricity of the tool is 11 ~ 7 mm, the magnitude of the eccentricity of the object is 3 ~ 3.5 mm. The diameter of the working surface of the tool 11 is: 40-14 = 26 (mm). The movement of the object 3 along the working surface of the tool 11 is not more than: 26-7 = 19 (mm).

At the moment of touching the tool 11 and object 3, a solution of a surface-active substance (SAS) based on fluorine-containing oligomers (for example, an oligomer of hexofluoropropanol and a haloalkyl ether of carboxylic acid) with the addition of ultrafine diamond abrasive (UDD) can be supplied from the device 19 to the contact area. The grain size of UDD in this case is ~ 5 nm.

The pressure block 16 of the tool 11 on the object 3 allows you to change the pressure during processing within a certain frequency interval within 2.5 · 10 ⁵ Pa ÷ 6.0 · 10 ⁵ Pa, which makes effective interaction on the treated surface of the object 3 surfactant and UDD.

During processing, ultrasonic vibrations from object 1 and ultrasonic vibrations generation device 4 and second ultrasonic vibrations generation device 12 can be supplied to object 3 and tool 11, vibrations in the range 55–65 kHz are supplied to tool 11, and vibrations in the range 30–30 are supplied to object 3 45 kHz.

Using this processing method provides a surface roughness of the diamond plate (object 3) at a level of from 0.16 to 1.9 nm. When processing the surface of a diamond plate, the parameters of its morphology (roughness R _a , root-mean-square roughness R _q , height range R _max ) were controlled using an atomic force microscope (ACM) of the P-47 Solver brand NT MDT (Russia) and calculated according to the standard laid down in microscope software.

Light areas (figure 2) are protrusions on the surface, dark areas are depressions on the surface of the diamond plate. Surface scan area: 1.4 × 1.4 μm.

The roughness of the surface of the diamond plate after processing was: R _a = 0.54 nm, the root mean square roughness R _q = 0.70 nm, the height swing R _max = 6.48 nm.

Using this method of processing the surface of a solid body made it possible to carry out the molecular beam epitaxy process and allowed to grow a single-crystal silicon film on diamond plates [7], which also extends the functionality of the method.

LITERATURE

1. Shulga V.G .; Denisenko V.P .; Kozlov Yu.F .; Khokhlov A.I. The method of one-sided polishing of flat surfaces of parts. RF patent number 2159173, publication date 11/20/2000.

2. V.Yu. Karasev. A method of processing flat surfaces and a device for its implementation. USSR copyright certificate, SU 1541034 A1, publication date 02/07/1990.

3. Khudobin L.V., Berdichevsky E.G. Technique for the use of cutting lubricants in metalworking. - M.: Mechanical Engineering, 1977 .-- 189 p.

4. Khmelev V.N., Barsukov R.V., Tsyganok S.N. Ultrasonic dimensional processing of materials: Scientific monograph / Alt. state Tech. Un-t. them. I.I. Polzunova. - Barnaul: ed. Altai State Technical University, 1997 .-- 120 p.

5. M.P. Kozochkin, N.V. Solis Pinargote. Study of the features of vibration turning. // Machine park. - MAY 2012.P. 73-77.

6. Mathematical Encyclopedic Dictionary. M. "Soviet Encyclopedia", 1988

7. V.Yu. Karasev, V.D. Kryukov, M.G. Kuznetsov, S.M. Pintus, M.A. Lamin, O.P. Pchelyakov, L.V. Sokolov. Features of the growth of silicon films on diamond substrates. // Microelectronics. - 2005. - T.34. - No. 1. - S. 37-42.

Claims (5)

1. A method of processing the surface of a solid body, including the mutual movement of the tool and the solid body, characterized in that the tool and the solid body are set to regular cyclic and periodic movements to ensure that the frequency ratio of the cyclic movements of the tool and the solid object is greater than one and not equal to an integer, while the movements of arbitrary points on the surfaces of the tool and the solid are described by transcendental curves. 2. The method according to claim 1, characterized in that the movements of arbitrary points on the surface of the tool and the solid are defined by different trajectories of cycloidal curves, while the types of trajectories of cycloidal curves are periodically changed. 3. The method according to claim 1, characterized in that a solution of a surfactant with an ultrafine abrasive is added to the contact area of the tool with the solid, while the pressure of the tool on the object is periodically changed. 4. The method according to claim 1, characterized in that the instrument and the solid additionally supply ultrasonic vibrations, while the ratio of the frequencies of these vibrations is not equal to an integer. 5. The method according to claim 1, characterized in that it additionally algorithmically sets the joint change of the trajectories of the cycloidal curves of the tool and the solid, ensuring the ratio of the frequencies of the tool and the solid is greater than one and not equal to an integer.

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