JP5177647B2 - Fluid polishing equipment - Google Patents

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 at the central portion in (2) decreased. 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, the fluid polishing apparatus according to the present invention is a fluid polishing apparatus that performs surface polishing of an object to be polished by injecting fluid toward the surface of the object to be polished from an injection port of an injection unit. The injection unit is integrally connected to the nozzle in which the nozzle side pressure feed path through which the fluid is pumped is formed, and the head side pressure feed path and the head side pressure feed path that receive and further pump the fluid sent from the nozzle side pressure feed path. An ejection port that is opposed to the surface of the object to be polished, and ejects the fluid that has flowed through the head-side pressure feed path from the ejection port; and the fluid that is ejected from the ejection port through the ejection head in a predetermined direction The nozzle and the ejection head are configured to be separated from each other and arranged at a predetermined interval.

  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 with a rectangular plate-like body, 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 31 to which the slurry 3 is supplied from the slurry pumping unit 20, an injection head 40 that is installed below the nozzle 31 and injects the slurry 3 from the injection port 43, and a side surface of the injection head 40. The ultrasonic generator 50 is provided to apply vibration to the jet head 40. The nozzle 31 and the ultrasonic generator 50 are fixed and held by holding frames 39 and 59 that are respectively supported by the base 61 of the substrate holding unit 60.

  As shown in FIG. 2, the nozzle 31 is formed in a substantially cylindrical shape extending in the up-down direction. In the central portion of the nozzle 31, the high-pressure slurry 3 fed from the slurry pumping unit 20 is made to flow. A nozzle side pressure feed path 32 extends in the vertical direction and penetrates, and a jet outlet 33 is formed at the center of the tip (lower end) to feed the high-pressure slurry 3 to the head side. In addition, a ring-shaped groove 34 that opens downward is formed at the tip (lower end) of the nozzle 31, and the nozzle 31 is arranged so that the upper end of the ejection head 40 enters the ring-shaped groove 34. Therefore, the ring-shaped groove 34 plays a role as a labyrinth seal, thereby preventing the slurry 3 ejected from the ejection port 33 of the nozzle 31 toward the ejection head 40 from being scattered.

  The ejection head 40 is separated from the nozzle 31 at a predetermined interval on the lower side of the nozzle 31, and is attached to the vibration generating device 50 so as to be coaxial with the central axis of the nozzle 31. The jet head 40 is formed in a substantially cylindrical shape extending in the vertical direction from a wear-resistant resin or a wear-resistant material having a surface coated with diamond coating or the like. Supply hole 41 surrounded and formed by a tapered inner surface, a head side pressure feed path 42 integrally connected below the supply hole 41 and extending in the vertical direction (injection direction), the supply hole 41 and the head side There is an injection port 43 for injecting (downward) the high-pressure slurry 3 that has flowed through the pressure feed path 42 toward the glass substrate 2 that is the object to be polished. Thereby, the ejection head 40 receives the high-pressure slurry 3 delivered from the ejection port 33 of the nozzle 31 through the supply hole 41 and causes the head-side pressure feed path 42 to flow, and the high-pressure slurry 3 is transferred from the ejection port 43 to the glass substrate 2. Can be injected in a substantially straight line. At this time, since the supply hole 41 is formed in a substantially conical shape, it is possible to smoothly flow the slurry 3 ejected from the nozzle 31 to the head side pressure feed path 42.

  Further, the inner diameter of the ejection port 43 (and the head-side pressure feeding path 42) of the ejection head 40 is set slightly larger (for example, about 10% larger) than the inner diameter of the ejection port 33 (nozzle-side pressure feeding path) of the nozzle 31, It is preferably about 0.5 mm to 10 mm. If the inner diameter of the ejection port 43 (and the head-side pressure feed path 42) of the ejection head 40 is set too large, the flow velocity of the slurry 3 to be ejected decreases, the kinetic energy decreases, and the polishing power decreases. Accordingly, it is set appropriately so that a good polishing power can be obtained.

  The nozzle 31 and the ejection head 40 have a central axis coaxial, and the upper end portion of the ejection head 40 has a predetermined distance between the ring-shaped groove 34 of the nozzle 31 and the wall portion forming the ring-shaped groove 34. Arranged at intervals.

  The ultrasonic generator 50 generates vibration by converting electrical vibration output from a high-frequency transmitter (not shown) into mechanical vibration via a vibrator (not shown). Then, the generated vibration is expanded several times by the amplitude-enlarging horn 51 and transmitted to the ejecting head 40, whereby the entire ejecting head 40 is vibrated in the horizontal direction as indicated by an arrow A in FIG. Is generated. For this reason, the slurry 3 flowing in the head-side pressure feed path 42 is also activated by imparting (transmitting) horizontal vibrations by ultrasonic waves, so that the polishing rate can be further increased in fluid polishing using the slurry 3. Can be improved.

  Further, as described above, because the nozzle 31 is separated from the lower surface side of the nozzle 31 and the upper surface side of the ejection head 40 by a predetermined interval, the vibration applied by the ultrasonic generator 50 is ejected from the ejection head. It is only necessary to transmit to 40, and it is not necessary to apply vibration to the entire slurry injection unit 30. For this reason, since it is sufficient to control the vibration applied to the ejection head 40, the control of the ultrasonic generator 50 can be simplified, and a powerful ultrasonic vibration can be efficiently applied to the slurry 3, thereby reducing the size. Can be realized. The amplitude of the vibration applied from the ultrasonic generator 50 to the ejection head 40 side is preferably adjusted to about several tens of μm. At this time, the upper end portion of the ejection head 40 that vibrates in the ring-shaped groove 34 due to the amplitude is prevented from colliding with and colliding with the lower end portion (wall portion in the ring-shaped groove 34) of the separated nozzle 31. For this reason, the predetermined interval is preferably at least twice as large as the amplitude of vibration to be applied, for example, about 0.1 mm.

  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 collection tank 63 is provided, and a holding table 64 that is fixed in the collection layer 63 and can removably hold the glass substrate 2 as an object to be polished on the surface side (upper surface side). For this reason, by moving the moving stage 62 by the drive mechanism, the glass substrate 2 held on the front surface side (upper surface side) of the holding table 64 is moved to an arbitrary position below the slurry jetting unit 30 (jet head 40). It is possible to perform polishing. Further, the slurry 3 sprayed and reflected from the slurry injection unit 30 onto the surface (upper surface) of the glass substrate 2 and the slurry 3 flowing down from the surface of the glass substrate 2 and the like 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 reused efficiently.

  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, an abrasive that has become smaller than a predetermined abrasive grain size by being used for polishing (processing), an abrasive that has become larger than a predetermined abrasive grain size range by agglomeration, etc., and an object to be polished ( By discharging unnecessary things such as chips of the glass substrate 2), only the reusable slurry 3 (abrasive) is returned to the slurry supply unit 10 and circulated.

  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 upper surface side of the holding table 64. Then, the moving 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 slurry jetting unit 30 (jet head 40), and the glass substrate 2 (desired portion to be polished). ) Is disposed at a position facing the ejection port 43 of the ejection head 40. At this time, the distance between the ejection port 43 of the ejection head 40 and the surface (upper surface) of the glass substrate 2 is such that the slurry 3 ejected from the ejection head 40 is efficiently ejected on the surface of the glass substrate 2 in a substantially linear shape. Keep the distance so that you can.

  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 pressurized and adjusted by the slurry pressure feeding unit 20, and the nozzles of the nozzles 31 are connected via the pipe line 80. Supply to the side pressure feed path 32. The supplied slurry 3 flows downward through the nozzle-side pressure feed path 32, is then ejected from the ejection port 33, and is delivered to the supply hole 41 of the ejection head 40. At this time, as described above, the slurry 3 ejected to the supply hole 41 is smoothly sent to the head-side pressure feed path 42 along the tapered inner surface of the supply hole 41, and partially on the tapered inner surface of the supply hole 41. Even if there is the slurry 3 reflected and bounced, it is received in the ring-shaped groove 34 of the nozzle 31, so that it is prevented from scattering outside. The slurry 3 flowing in the head-side pressure feed path 42 of the ejection head 40 is activated by applying strong horizontal vibration from the ultrasonic generator 50 via the ejection head 40, thereby activating the slurry 3. The The ejection head 40 ejects the slurry 3 from the ejection port 43 as a high-pressure and high-speed jet and collides with the surface (upper surface) of the glass substrate 2 disposed at a position directly opposite to the ejection port 43, whereby the glass substrate The surface (upper surface) of 2 is polished.

  Next, the state in which the surface (upper surface) of the glass substrate 2 that is the object to be polished is polished by the fluid polishing apparatus 1 will be described in detail with reference to FIGS.

  Conventionally, for the slurry 3 ejected from the ejection port 43 in the fluid polishing, the horizontal linear velocity (flow velocity) at the center of the jet is almost zero, and this horizontal line gradually increases toward the outside. Since the speed is generated, details will be described later using the Preston equation shown below. However, there is no processing capability at the center of the jet, and the processing capability increases toward the outside. The shape of the polishing spot was substantially ring-shaped (see FIG. 4).

At this time, as a formula for determining the processing amount (polishing amount) U, the following Preston formula is generally used.
U = k, P, v, t
Here, k is a constant, P is a contact pressure applied to the object to be polished by the slurry (abrasive), v is a relative linear velocity (in the horizontal direction) between the object to be polished and the slurry (abrasive), and t is an object to be polished. It is the contact time between the slurry and the abrasive (abrasive). According to the Preston equation, in the polishing process, the relative linear velocity v between the object to be polished and the slurry (abrasive) is one factor that determines the processing amount U, and this relative linear velocity. The polishing rate (polishing efficiency) increases as the value increases, and the polishing rate decreases as the relative linear velocity decreases. In other words, no matter how much the contact pressure P applied to the object to be polished is increased, if a relative linear velocity does not occur between the object to be polished and the slurry (abrasive), the processing capability is reduced and the desired processing accuracy is reduced. It can be said that it is difficult to perform the polishing for obtaining the above.

  In other words, no matter how much the injection pressure P of the slurry 3 (abrasive material) is adjusted and sprayed from the injection port 43 to collide with the glass substrate 2 that is the object to be polished, the slurry 3 (abrasive material) is relative to the glass substrate 2. If the typical linear velocity (linear velocity in the horizontal direction) is low, it is difficult to improve the polishing rate.

  Therefore, in the present fluid polishing apparatus 1, the entire jet flow of the slurry 3 is disturbed by applying the ultrasonic vibration in the horizontal direction to the slurry 3 ejected by the ultrasonic generator 50 via the ejection head 40 and activating the slurry 3. It becomes a flow state, and a larger linear velocity can be generated as a relative moving velocity between the glass substrate 2 and the slurry 3 (abrasive), thereby further improving the polishing rate.

  At this time, the horizontal linear velocity was not originally generated in the central portion of the jet of the slurry 3, but when ultrasonic vibration is applied to the slurry 3, the central portion of the jet of the slurry 3 A large horizontal linear velocity based on the vibration is generated. On the other hand, at the periphery of the jet, the horizontal linear velocity originally generated from the central portion toward the outer periphery in the jet and the horizontal linear velocity due to the ultrasonic vibration were canceled out. This linear velocity decreases. As a result, as shown in FIG. 3, since the horizontal linear velocity is increased in the central portion of the jet, it is possible to form a polishing spot shape having a Gaussian distribution with a strong polishing capability in the central portion of the jet. The polishing rate at the central portion of the glass substrate can be improved to efficiently polish a desired portion on the glass substrate, and the processing accuracy in polishing the glass substrate can be improved. Further, in fluid polishing, since the position control of the processing can be performed with the central portion (center portion) of the jet as a base point, the controllability of fluid polishing is improved.

  Furthermore, since the linear velocity generated by the ultrasonic vibration is proportional to the product of the frequency and amplitude of this vibration, adjusting the frequency and amplitude to optimize the linear velocity can further improve the polishing rate. it can.

  As described above, according to the fluid polishing apparatus 1 of the present embodiment, the slurry generator 30 activates the slurry 3 by applying strong ultrasonic vibrations to the slurry 3 via the single-structured jet head 40. Therefore, it is possible to improve the polishing rate in fluid polishing, and it is possible to realize an efficient and highly accurate polishing process close to a Gaussian distribution polishing spot shape.

  In the slurry injection unit 30, the nozzle 31 and the injection head 40 need only be provided separated by a predetermined interval, and are separately fixed and held by the holding frames 39 and 59 as illustrated in this embodiment. Alternatively, they may be connected and fixedly held by a single holding frame or the like. Further, when the nozzle 31 and the ejection head 40 are held by a single holding frame or the like, it is preferable to provide a vibration absorber for absorbing vibration transmitted to the nozzle 31.

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 the schematic which shows the state of the grinding process by the fluid grinding | polishing apparatus of this embodiment. It is the schematic which shows the state of the grinding process by the conventional fluid grinding | polishing apparatus.

Explanation of symbols

1 Fluid polishing device 2 Glass substrate (polishing object) 3 Slurry (fluid)
30 Slurry injection part (injection part) 31 Nozzle 32 Nozzle side pressure feed path
34 Ring-shaped groove (groove) 40 Ejection head 41 Supply hole (opening)
42 Head side pressure feed path 43 Injection port
50 Ultrasonic generator (vibration generator, ultrasonic generator)

Claims (7)

A fluid polishing apparatus that performs surface polishing of the polishing object by spraying a fluid toward the surface of the polishing object from an injection port of an injection unit,
The injection unit is
A nozzle formed with a nozzle side pressure feed path through which fluid is pumped;
The head side pressure feed path is formed integrally with the head side pressure feed path for receiving and flowing the fluid fed from the nozzle side pressure feed path and facing the surface of the object to be polished. An ejection head that ejects the fluid that has flowed through the ejection port;
A vibration generating unit that applies vibration in a predetermined direction to the fluid ejected from the ejection port via the ejection head;
The fluid polishing apparatus, wherein the nozzle and the ejection head are separated from each other and arranged at a predetermined interval.   The fluid polishing apparatus according to claim 1, wherein the predetermined direction is a direction parallel to a portion to be polished on the surface of the object to be polished.   2. The fluid polishing apparatus according to claim 1, wherein the predetermined direction is a direction perpendicularly intersecting an ejection direction of a fluid ejected from the ejection port.   The fluid polishing according to any one of claims 1 to 3, wherein the vibration generation unit includes an ultrasonic generation unit that applies ultrasonic vibration to the fluid ejected from the ejection port. apparatus.   5. The jet head according to claim 1, wherein the jet head is configured to open at an end portion on the nozzle side and to have a substantially conical opening portion communicating with the head-side pressure feed path. The fluid polishing apparatus according to 1.   6. The nozzle according to claim 1, wherein the nozzle has a groove portion in which an end portion on the side opposite to the ejection port of the ejection head can be loosely inserted at an end portion on the ejection head side. The fluid polishing apparatus according to any one of the above.   The ejection head is disposed in the groove portion of the nozzle apart from an inner wall portion that forms the groove portion with an interval of at least twice as large as the amplitude of vibration applied by the vibration generating portion. The fluid polishing apparatus according to claim 6.

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