JP2009279731A - Fluid polishing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fluid polishing device capable of improving a polishing rate in fluid polishing. <P>SOLUTION: This fluid polishing device is provided with a nozzle 40 having an injection port 42 by which slurry 3 for polishing a surface 2a of a polishing object 2 is injected, and a reflection head 50 having a reflecting surface 51 arranged oppositely to the injection port 42 and reflecting the slurry 3 injected from the nozzle 40 toward the surface 2a of the polishing object 2 by the reflecting surface 51. The reflecting surface 51 of the reflection head 50 is formed into a curved surface shape having a geometrical focus. In the reflection head 50, the focus of the reflecting surface 51 is located in the surface 2a of the polishing object 2 or in the vicinity of the surface 2a, and the slurry 3 reflected from the reflecting surface 51 is arranged to be substantially converged at the focus. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fluid polishing apparatus that performs polishing by jetting a fluid toward the surface of an object to be polished such as a glass substrate.

  As a polishing apparatus that polishes the surface of an object to be polished such as a glass substrate, for example, the object to be polished held on a rotary table and a polishing pad mounted on a polishing head of the polishing apparatus are pressed while relatively rotating. It is known that a polishing process is performed by bringing a slurry according to a processing target between the polishing target and the polishing pad and supplying a slurry according to the processing target. In such a polishing apparatus, it is difficult to uniformly apply the contact pressure by the polishing pad to the entire surface to be polished, and the dimensional accuracy of the surface to be polished changes due to the difference in the contact pressure. Further, when the polishing pad is worn out, damage such as scratches is given to the surface to be polished.

On the other hand, a fluid polishing apparatus that polishes the surface of an object to be polished by ejecting a fluid such as slurry (polishing fluid) from an ejection unit is known (for example, see Patent Document 1). In such a fluid polishing apparatus, polishing is performed by directly impinging the fluid adjusted to a high pressure on the surface of the object to be polished without using a tool such as a polishing pad, so that a highly polished surface can be obtained. Can do.
Japanese Patent Laid-Open No. 10-50810

  In polishing processing, due to Preston's law, the relative moving speed (relative linear speed) generated between the jetted fluid and the polishing object is one factor that determines the polishing amount (processing amount). It is known that the polishing rate is improved when the relative linear velocity is increased, and the polishing rate is decreased when the relative linear velocity is decreased. In the fluid polishing apparatus as described above, the injection unit is generally installed so as to be perpendicular to the surface of the object to be polished, and the fluid from the injection unit is substantially linear with respect to the surface of the object to be polished. It is jetted vertically. However, since there is almost no relative linear velocity (moving speed) between the fluid and the object to be polished in the central portion of the jet jetted from the jet section of such a fluid polishing apparatus, this jet flow It was a factor that the polishing rate in the central part of the steel was lowered. Thus, when the polishing rate at the central portion of the jet is low, it becomes difficult to control the position and conditions in the polishing, so that there is a problem that productivity is lowered and processing accuracy is also deteriorated.

  On the other hand, there are various techniques in which the jet nozzle is installed obliquely with respect to the surface of the object to be polished and the fluid to be injected is incident obliquely with respect to the surface to be polished to generate a relative linear velocity. However, according to this, the processing pressure applied to the surface to be polished is dispersed, and as a result, the polishing rate is lowered.

  This invention is made | formed in view of such a subject, and it aims at providing the fluid polishing apparatus which can improve a polishing rate in fluid polishing.

  In order to achieve such an object, a fluid polishing apparatus according to the present invention includes an injection unit having an injection port through which a fluid for performing surface polishing of an object to be polished is injected, and a reflection disposed to face the injection port. And a reflection head that reflects the fluid ejected from the ejection unit toward the surface of the object to be polished by the reflection surface, and the reflection surface of the reflection head is formed in a curved surface shape having a geometric focus. The reflecting head is disposed so that the focal point of the reflecting surface is located at or near the surface of the object to be polished and the fluid reflected from the reflecting surface is substantially converged on the focal point.

  According to the present invention, the polishing rate in fluid polishing can be improved.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. A schematic configuration of a fluid polishing apparatus according to the present embodiment is shown in FIG. The fluid polishing apparatus 1 is an apparatus that polishes the surface of an object to be polished by the flow of a polishing fluid (slurry), and includes a slurry supply unit 10, a slurry pumping unit 20, a slurry injection unit 30, a substrate holding unit 60, and a slurry collection unit 70. , And a conduit 80 connecting them. The polishing object of the fluid polishing apparatus 1 is a glass substrate 2 such as quartz glass, for example. The glass substrate 2 is usually polished in a rectangular plate state, but the shape is not limited to this.

  The slurry supply unit 10 is an agitation tank that generates slurry (polishing fluid) 3 by stirring and mixing abrasives (abrasive particles) and pure water, and supplies the slurry 3 to the slurry pumping unit 20. For example, silica particles (such as colloidal silica) are used as the abrasive, and the average primary particle diameter of the abrasive used is preferably several nm to several tens of nm. Further, in order to improve the dispersibility and stability of the slurry (abrasive particles) 3, it is preferable that a dispersant such as ammonium polymethacrylate is added to the slurry 3.

  The slurry pumping unit 20 is a high-pressure pump that pressurizes and feeds the slurry 3 sent from the slurry supply unit 10, and the slurry 3 pumped at this high pressure is supplied to the slurry jetting unit 30 and then is a glass as a polishing object. Sprayed onto the substrate 2. In addition, a pressure adjusting valve 21 is connected between the slurry pumping unit 20 and the slurry injection unit 30 (via a pipe line 80 that conveys the slurry 3), and is connected to an object to be polished (such as its processing accuracy). It can be adjusted to a suitable supply amount and pressure of the slurry 3.

  The slurry injection unit 30 includes a nozzle 40 that injects the slurry 3 supplied from the slurry pumping unit 20 from the injection port 42, and a reflection head 50 that reflects the slurry injected from the injection port 42 toward the glass substrate 2. Configured. The nozzle 40 and the reflection head 50 are integrally connected and fixedly held by a holding frame 39 supported by the base 61 of the substrate holding unit 60.

  As shown in FIG. 2, the nozzle 40 is formed in a hollow cylindrical shape extending in the horizontal direction (X direction), and the high-pressure slurry 3 fed from the slurry pumping unit 20 is placed at the center of the nozzle 40. A pressure feed path 41 for pressure feeding is formed to extend in the central axis direction (X direction) of the nozzle 40, and the pressured high pressure slurry 3 is directed toward the reflection head 50 at the center of the tip (left end). An injection port 42 for injecting in the horizontal direction (X direction) is formed.

  The inner diameter of the injection port 42 (and the pressure feed path 41) of the nozzle 40 is changed according to the abrasive particle diameter of the abrasive used and the object to be polished, and is, for example, about 0.5 mm to 10 mm. Is preferred. If the inner diameter of the injection port 42 (and the pressure feed path 41) of the nozzle 40 is set too large, the flow rate of the injected slurry 3 is reduced, the kinetic energy is reduced, and the polishing force is reduced. It is preferable to set appropriately so that a sufficient polishing force can be obtained.

  The reflection head 50 is made of a wear-resistant resin or a wear-resistant material having a surface coated with a diamond coating or the like, and is recessed into a paraboloid (rotary paraboloid) shape on the side surface as shown in FIG. The reflecting surface 51 is a block-shaped member formed so as to face the ejection port 42 of the nozzle 40. Here, the paraboloid (rotational paraboloid) is a parabola when the reference parabola h is rotated around the central axis (target axis) x of the parabola h as shown in FIG. h is a surface composed of a set of points through which the reflecting surface 50 of the reflecting head 50 has a parabolic surface in an upper part when the reflecting surface 51 is cut by a horizontal plane located above the central axis x with respect to the parabolic surface. (Semi-parabolic surface).

The central axis (rotation axis) x of the parabola h serving as a reference for forming such a parabolic surface is provided so as to be parallel to the central axis (injection direction) of the nozzle 40 in a vertical plane. The parabola h is formed based on a mathematical formula indicating a parabola of z ² = 4bx (b> 0) in the relationship with the axis z orthogonal to the axis x in the vertical plane. The parabola h has an intersection point at which the axis x and the axis z intersect at the vertex O, and further has a focal point F on the axis x that is the central axis.

  With respect to the reflection head 50 having such a reflection surface 51, the jet of the slurry 3 from the nozzle 40 is ejected in parallel to the central axis x of the reflection surface (parabolic surface) 51 to the reflection surface 51. When incident, the jet of the slurry 3 can be converged toward the focal point F after being reflected by the reflecting surface 51 as shown in FIG. The angle formed by the tangent m at the collision position Q when the jet of the slurry 3 in the direction parallel to the central axis x of the reflecting surface (parabolic surface) 51 collides with the reflecting surface 51 is reflected by α. It is based on the geometric characteristics of a parabola (paraboloid) where α = β is always established, where β is the angle formed by the reflection direction of the jet of the slurry 3 (bounced) and the tangent m. is there.

  That is, the focal point F (and the axis x) of the reflecting surface (parabolic surface) 51 is positioned on the surface 2a of the glass substrate 2 that is the object to be polished, and a desired portion to be polished on the surface of the focal point F and the object to be polished. , The jet of the slurry 3 can be converged on the portion to be polished, and a high convergence pressure can be applied to the portion to be polished. Further, the jet of the slurry 3 is reflected by the reflecting surface 51, whereby a horizontal reflected flow (indicated by an arrow A in FIG. 2) is generated in the jet of the slurry 3 with respect to the surface 2 a of the glass substrate 2. The relative linear velocity (moving speed) in the polishing process can be obtained with respect to (the portion to be polished).

By the way, in general, as a formula for determining the processing amount (polishing amount) U in the polishing process, the following Preston formula is used.
U = k, P, v, t
Here, k is a constant, P is a contact pressure applied by the slurry (abrasive) to the object to be polished, v is a relative linear velocity between the slurry (abrasive) and the object to be polished, t is an object to be polished and the slurry (abrasive) ) Contact time. According to the Preston equation, in the polishing process, the contact pressure P and the relative linear velocity v between the object to be polished and the slurry (abrasive material) are factors that determine the processing amount (polishing amount) U. As P and relative linear velocity v increase, the polishing rate (polishing efficiency) improves, and as contact pressure P and relative linear velocity v decrease, the polishing rate decreases.

  For this reason, as described above, the jet of the slurry 3 ejected from the nozzle 40 is reflected by the reflecting surface 51 of the reflecting head 50, and the portion to be polished coincides with the focal point F of the reflecting surface (parabolic surface) 51. By converging the jet of the slurry 3, a high convergence pressure P is applied to the center of the portion to be polished, and a relative linear velocity v due to the reflected flow is generated with respect to the portion to be polished. Can be improved.

  The lower end surface 52 of the reflection head 50 is preferably formed so as to be positioned, for example, about 0.1 mm above the surface 2a of the glass substrate 2 that is an object to be polished during polishing. Thus, the focal point F of the reflecting surface (parabolic surface) 51 can be positioned on the surface (surface to be polished) 2a of the glass substrate 2 while preventing interference between the reflecting head 50 and the glass substrate 2.

  As shown in FIG. 1, the substrate holding unit 60 includes a horizontal base 61, a moving stage 62 that can be moved in a three-dimensional direction (X, Y, and Z directions) by a driving mechanism (not shown), and a moving stage 62. A recovery tank 63 is provided, and a holding table 64 that is fixed in the recovery tank 63 and can removably hold the glass substrate 2 as an object to be polished on the front surface side (upper surface side). For this reason, by moving the moving stage 62 by the driving mechanism, the focal point F of the reflecting surface (parabolic surface) 51 of the reflecting head 50 is placed at an arbitrary position on the surface 2a of the glass substrate 2 held by the holding table 64. The portion where the focal point F is located can be polished as the portion to be polished of the glass substrate 2. Further, the slurry 3 sprayed and bounced from the slurry injection unit 30 onto the surface 2a of the glass substrate 2 and the slurry 3 flowing down from the surface 2a of the glass substrate 2 are prevented from being scattered outside by the recovery tank 63. At the same time, it is recovered by the slurry recovery unit 70 and efficiently reused.

  The slurry recovery unit 70 recovers the slurry 3 discharged through a discharge hole (not shown) formed in the lower surface corner of the recovery tank 63 via a pipe line 80, and filters the recovered slurry 3 into a filter. After purifying with a classifier 71 equipped with the above, etc., it is returned to the slurry supply unit 10. In this classifier 71, the abrasive particle size (slurry 3) becomes smaller than the predetermined abrasive particle size by being used for polishing (processing), and becomes larger than the predetermined abrasive particle size range due to aggregation or the like (slurry). 3) By discharging unnecessary materials such as abrasives and chips of the glass substrate 2, only the reusable slurry 3 (abrasive) is returned to the slurry supply unit 10 and circulated. ing.

  Next, a case where a polishing object is polished using the fluid polishing apparatus 1 having such a configuration will be described. In order to polish the glass substrate 2 by the fluid polishing apparatus 1, first, the glass substrate 2 to be polished is attached and held on the front surface side (upper surface side) of the holding table 64. Then, the movable stage 62 is moved by a driving mechanism (not shown) so that the glass substrate 2 on the holding table 64 is positioned below the nozzle 40 and the reflection head 50, and a desired portion to be polished on the surface 2 a of the glass substrate 2. Is placed at a position that matches the focal point F of the reflecting surface (parabolic surface) 51. At this time, for example, it is preferable to set the moving coordinate system of the moving stage 62 by the driving mechanism with the focus F as the center (processing origin).

  Next, in order to inject the slurry 3 by the slurry injection unit 30, first, the slurry 3 sent from the slurry supply unit 10 is pressure-adjusted to a high pressure by the slurry pressure supply unit 20, and the nozzle 40 is connected via the conduit 80. To the pressure feed path 41. The slurry 3 supplied to the pressure feed path 41 flows through the pressure feed path 41 toward the ejection port 42, and is then ejected from the ejection port 42 toward the reflection surface 51 of the reflection head 50 as a high-pressure and high-speed jet flow. Then, the jet of the slurry 3 is reflected (rebounded) by the reflecting surface 51 and converges on the portion to be polished on the surface 2a of the glass substrate 2 where the focal point F of the reflecting surface (parabolic surface) 51 is located. As described above, this is because a jet parallel to the central axis of the paraboloid (parabola) is reflected on the parabola (parabola) and converges to the focal point of the parabola (parabola). It utilizes the geometric features of the object surface (parabola).

  Thereby, the jet of the slurry 3 is converged on the portion to be polished on the surface 2a of the glass substrate 2 where the focal point F of the reflecting surface (parabolic surface) 51 is located, and a high convergence pressure (P) is applied to this portion to be polished. In addition, the relative linear velocity (v) due to the reflected flow is generated with respect to the portion to be polished, whereby the polishing rate in polishing the glass substrate 2 can be improved.

  At this time, since the jet of the slurry 3 converges to the focal point F, a polishing spot shape having a Gaussian distribution with a strong polishing force at the central portion (focal point F) of the jet can be formed in the portion to be polished. The polishing rate at the center of the glass substrate 2 can be further improved so that a desired portion on the glass substrate 2 can be efficiently polished and the processing accuracy in polishing the glass substrate 2 can be improved. Further, since the position control of the polishing process can be performed with the central portion (center portion) of the jet flow in the fluid polishing as a base point, the controllability of the fluid polishing is improved.

  As described above, according to the fluid polishing apparatus 1 of the present embodiment, the slurry 3 that is the polishing fluid is reflected by the reflecting surface (parabolic surface) 51 and converged to the focal point F located on the surface to be polished, thereby fluid polishing. It is possible to improve the polishing rate and to achieve an efficient and highly accurate polishing process close to the shape of a polishing spot having a Gaussian distribution.

  In the above-described embodiment, the example in which the reflection surface 51 of the reflection head 50 is formed in a parabolic shape has been described. However, the technical scope of the present invention is not limited to this, and for example, an example thereof. As shown in FIG. 4, the reflection surface 51 'of the reflection head 50' may be formed in an elliptical shape.

  At this time, the first focal point (one focal point) G1 of the elliptical surface is positioned on the central axis of the nozzle 40, and the second focal point (other focal point) G2 of the elliptical surface is located on the portion to be polished of the surface 2a of the object to be polished. Is configured such that the jet of the slurry 3 ejected from the nozzle 40 is reflected by the reflecting surface 51 'and converged on the portion to be polished where the second focal point G2 is located. According to this, as in the above-described embodiment, a high convergence pressure (P) and a relative linear velocity (v) can be generated in the portion to be polished to improve the polishing rate, and a spot with a Gaussian distribution can be obtained. A shape can be formed. This uses the geometric feature of the ellipsoid (ellipse) that the jet from one focal point is reflected on the ellipsoid (ellipse) and concentrated on the other focal point. Is.

  In the above-described embodiment, the nozzle 40 and the reflection head 50 are integrally connected and held by the holding frame 39. However, the present invention is not limited to this, and only the nozzle 40 is swung in the vertical direction. A drive mechanism for moving the nozzles 40 and the reflection head 50 may be provided by providing a driving mechanism. Even if the entire nozzle 40 is swung in the vertical direction, as long as the jet of the slurry 3 ejected from the nozzle 40 is incident on the reflecting head 50 parallel to the central axis x of the paraboloid (parabola h), Since all the jets reflected by the reflecting surface 51 converge on the focal point F of the paraboloid (parabola h), the jets reflected from multiple directions collide with the portion to be polished (focal point F) by swinging in the vertical direction. In addition, more efficient polishing can be performed.

  In the above-described embodiment, the central axis x of the reflective surface (parabolic surface) 51 of the reflective head 50 and the central axis (injection direction) of the nozzle 40 are both set to extend in the horizontal direction (X direction). However, the present invention is not limited to this, and the central axis x of the reflective surface (parabolic surface) 51 of the reflective head 50 and the central axis (ejection direction) of the nozzle 40 may be disposed in parallel. Therefore, for example, both may be set obliquely with respect to the surface to be polished.

It is a front view which shows roughly the structure of the fluid polishing apparatus of this embodiment. It is front sectional drawing which shows the slurry injection part of the fluid polishing apparatus of this embodiment. It is a figure for demonstrating the shape of the reflective surface of the fluid polishing apparatus of this embodiment. It is a figure for demonstrating the shape of the reflective surface of the fluid polishing apparatus of different embodiment.

Explanation of symbols

1 Fluid polishing device 2 Glass substrate (polishing object) 3 Slurry (fluid)
30 Slurry injection unit 40 Nozzle (injection unit) 42 Ejection port 50, 50 'Reflection head 51, 51' Reflection surface F Focus G1 First focus (one focus) G2 Second focus (focus, other focus)

Claims (4)

An injection unit having an injection port through which a fluid for polishing the surface of the object to be polished is injected;
A reflection head that is disposed to face the ejection port and includes a reflection head that reflects the fluid ejected from the ejection unit toward the surface of the object to be polished by the reflection surface;
The reflective surface of the reflective head is formed in a curved shape having a geometric focal point,
The reflective head is disposed so that the focal point of the reflective surface is positioned at or near the surface of the object to be polished and the fluid reflected from the reflective surface substantially converges to the focal point. A fluid polishing apparatus characterized by the above. The reflecting surface is formed into a concave curved surface shape having at least a part of a paraboloid having a focal point on the central axis;
The ejection unit is arranged so that the ejection direction of the fluid from the ejection port is parallel to the central axis of the paraboloid of revolution,
2. The fluid polishing apparatus according to claim 1, wherein the focal point of the paraboloid of revolution is configured to be positioned on the surface of the object to be polished or in the vicinity of the surface. The central axis of the paraboloid is disposed on the surface of the object to be polished;
Of the surface consisting of a set of points through which the parabola passes when the rotary parabola rotates a predetermined parabola around the central axis as a rotation center, the surface of the object to be polished is on the injection unit side. The fluid polishing apparatus according to claim 2, wherein the fluid polishing apparatus is formed in a semi-paraboloid shape located at a position. The reflective surface is formed into a concave curved surface having a part of a spheroid having at least two focal points;
One focal point of the rotary paraboloid is positioned on the central axis of the injection unit, and the other focal point of the rotary paraboloid is positioned near the surface of the polishing object or the surface. 2. The fluid polishing apparatus according to claim 1, wherein the fluid ejected from the ejection unit located on a focal point is configured to be reflected by the reflecting surface and substantially converge to the other focal point. 3. .

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