JPH11320385A - Polishing method and its device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polishing method and a device therefor to maintain polishing on a sheet-form work in stable quality, improve working ratio, and reduce an arrangement space. SOLUTION: After a work is transferred to a polishing processing part 4a through a back washing part 3 and the surface thereof is polished, washing and drying are effected by a work washing part 5. A polishing head 8 to polish the work by the polishing processing part 4a is moved to a head washing part 4b and after dressing and washing are applied thereon, the polishing head is moved to a polishing processing part 4a again, and polishing on a subsequent work is executed. At the same time when the work is polished in a state that no foreign matter is adhered thereto through washing, the work is finished in a cleaned state, and since the polishing head 8 is maintained in a constantly specified state, polishing quality is stabilized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing apparatus for polishing a thin work such as a semiconductor wafer or a liquid crystal substrate.

[0002]

2. Description of the Related Art FIG. 5 shows the configuration of a polishing apparatus according to the prior art. This polishing apparatus is configured to polish the surface of a semiconductor wafer formed in a thin disk shape, and a plurality of semiconductor wafers 30 are accommodated in a work cassette 32 and supplied to a work supply unit 31. . The first transfer robot 33 takes out the semiconductor wafers 30 one by one from the work cassette 32 and transfers them to the centering unit 34. After the center position of the semiconductor wafer 30 is determined by the centering unit 34, the semiconductor wafer 30 is again taken out by the first transfer robot 33 and transferred to the temporary storage unit 35 so that the two semiconductor wafers 30 are arranged. .
The semiconductor wafer 30 placed in the temporary storage section 35 is sucked and held by the work carrier 36 at a position shifted by 180 degrees due to the rotation of the turntable of the temporary storage section 35.
The work carrier 36 moves linearly on the rail 41 and transfers the semiconductor wafer 30 sucked and held by the temporary holder 35 onto the polishing stage 37. The semiconductor wafer 30, whose surface has been polished by a polishing head (not shown) on the polishing stage 37, is sucked and held by the work carrier 36 again, and is transferred to the temporary holder 35. While the semiconductor wafer 30 is being polished on the polishing stage 37, the semiconductor wafer 30 to be polished next is placed in the temporary placing section 3.
5 is mounted on the turntable 5, so that the polished semiconductor wafer 3 is rotated by rotating the turntable 180 degrees.
The positions of the non-polished semiconductor wafer 30 and the non-polished semiconductor wafer 30 are switched, and the unpolished semiconductor wafer 30 is transferred to the polishing stage 37 as before, and the polished semiconductor wafer 30 is taken out by the first transfer robot 33. Is transferred to the second transfer robot 39 and stored in the storage unit 40.

The polishing stage 37 is dressed and cleaned by a dressing unit 38 together with the polishing head at the end of polishing. The dressing and cleaning are configured so as to wash the polishing stage 37 and the polishing head while applying water from the dressing unit 38 and to dress the polishing head. Further, in this conventional configuration, two sets of the temporary placing part 35, the work carrier 36, and the polishing stage 37 are arranged in parallel, and the first and second transfer robots 33,
The semiconductor device 30 is configured to be able to perform a parallel operation by transferring the semiconductor wafer 30 between the 39.

[0004]

The structure of the polishing apparatus in the above-mentioned prior art has the following problems.

(1) During polishing, the polishing liquid or the like is scattered. In order to avoid contamination of other works and components due to the scatter, it is necessary to dispose other works and components away from the polished portion. In addition, the size of the device is increased and the installation space is increased.

(2) Since the cleaning of the polishing head after polishing only involves removing water and dirt, it is difficult to maintain the surface state of the polishing head in a constant state, and frequent maintenance is required. When the frequency of stopping the operation of the apparatus for the maintenance of the head increases, the operation rate decreases.

(3) If foreign matter adheres to the work carried into the polishing stage, the work may be damaged during polishing or poor polishing may occur.

(4) Since the polished workpiece is discharged as it is, post-processing for removing dirt during polishing is necessary, and it becomes difficult to remove dirt as time elapses until the post-processing is performed. .

(5) Since no measures have been taken against a rise in the temperature of the polishing head, the polishing rate per unit time decreases due to a decrease in the polishing rate due to the temperature rise, and it is difficult to obtain a constant polishing state.

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems of the prior art, and has as its object to provide a polishing method and an apparatus therefor configured to perform polishing with a constant quality. It is.

[0011]

According to a first aspect of the present invention, there is provided a polishing method for polishing a surface of a work formed in a thin plate, wherein the work is placed on a polishing stage. After finishing the polishing step of polishing the surface of the work by a polishing head, the polished work is transferred to a work washing step of washing and drying,
A series of operations for moving the polishing head to a head cleaning step of performing dressing and cleaning are performed for each polishing process on each work.

According to this polishing method, the polished work is washed in the work washing step, so that the work is finished in a state in which the adhesion of the polishing liquid or the like has been removed. Further, the polishing head is dressed and cleaned in the head cleaning step every time polishing of the work is completed, so that a constant polishing quality can be always maintained.

In the above-mentioned polishing method, a pre-cleaning step of cleaning the work is carried out before the transfer to the polishing step, so that the work with foreign matters adhered thereto is transferred to the polishing step. Disappears. Grinding a workpiece with foreign matter may damage the thin plate-shaped work due to the pressure of the polishing head or cause poor polishing due to the foreign matter. No foreign substances are introduced into the process.

Further, the polishing step is performed in a closed space surrounding the polishing stage and the polishing head, thereby preventing other components from being contaminated by scattering of the polishing liquid or the like. . Further, the space provided around the polishing step can be reduced in order to avoid the influence of scattering of the polishing liquid and the like, and the installation space can be reduced by suppressing an increase in the size of the apparatus.

According to a second aspect of the present invention, there is provided a polishing apparatus for polishing a surface of a work formed in a thin plate, comprising: a work supply unit for supplying a work to be polished; A polishing section for polishing the surface of a work disposed on a polishing stage by a polishing head, a dressing stage for dressing the polishing head after polishing the work, and a head cleaning tank for cleaning the polishing head. A head cleaning unit, a work cleaning unit that cleans and dry the entire surface of the polished work, a work storage unit that stores the work that has been cleaned and dried, and a work supply unit that removes the work one by one from the work supply unit. A polishing section, a work cleaning section, a work transfer means for transferring the work to the work accommodating section, and a polishing section and a head cleaning section for the polishing head. Characterized by comprising comprises a head moving means for moving between.

According to this configuration, the work is taken out one by one from the work supply unit by the work transfer means and transferred to the polishing processing unit, the work cleaning unit, and the work storage unit in accordance with the progress of each processing step. . The work, the surface of which has been polished in the polishing section, is cleaned in the work cleaning section and taken out in a finished state to which no polishing liquid or the like adheres, so that the quality of product processing using this work can be improved. Further, the polishing head after polishing is moved to the head cleaning section by the head moving means and is dressed and cleaned, so that a stable polishing state can always be obtained.

In the above configuration, by providing a pre-cleaning section for cleaning the work taken out from the work supply section before transferring the work to the polishing section, foreign matter adhering to the work is brought into the polishing section. Is prevented,
The occurrence of defective polishing when the workpiece is polished in a state where foreign matter adheres to the workpiece is prevented. Since the work is formed in a thin plate shape, even if there is fine foreign matter, the work under pressure from the polishing head will be deformed, and the work will be damaged or polishing failure will occur, By providing the pre-cleaning unit, the occurrence of defects due to the adhesion of foreign matter is prevented.

Further, by providing the polishing section with shielding means for covering the periphery of the polishing stage and the polishing head when polishing is performed, scattering of the polishing liquid and the like is prevented by the shielding means. There is no need to provide a space around the polished portion to prevent the effects of scattering, and it is possible to suppress an increase in the size of the apparatus and reduce the installation space.

The above structure is provided with an air suction means for discharging the air surrounded by the shielding means, so that the scattered particles such as polishing mist are discharged to the outside by the air suction means. Scattering can be more effectively prevented, and contamination in the polished portion covered with the cover can be suppressed.

The head cleaning tank is provided with an ultrasonic cleaning means so that the cleaning effect can be enhanced and finer dirt can be removed.

Further, the polishing head is provided with a fluid circulating means for circulating a fluid in the polishing head and a temperature adjusting means for adjusting the temperature of the fluid, so that the temperature of the polishing head is kept constant. It is possible to prevent a decrease in the polishing rate due to a rise in the temperature of the polishing head,
It can be configured such that a constant polishing state is always obtained.

The work cleaning section is provided with a cleaning brush for cleaning the work and a centrifugal dehydrating means for scattering water adhering to the work, so that foreign substances such as polishing liquid and polishing residue adhering to the polished work are removed. It can be removed and taken out in a dry state, and the quality of the product using this work can be improved.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings to provide an understanding of the present invention.
The embodiment described below is an example embodying the present invention, and does not limit the technical scope of the present invention.

FIG. 1 shows the overall configuration of a polishing apparatus according to the present embodiment, which is configured so that a semiconductor wafer can be used as a workpiece to be polished and its surface can be polished to a mirror finish. The polishing apparatus 1 contains a plurality of semiconductor wafers 11 to be polished in a work cassette 10 and supplies the work wafers. Polishing provided with a pre-cleaning unit 3 for cleaning the semiconductor wafer 11 before being transferred to the wafer 4a, a polishing processing unit 4a for polishing the surface of the semiconductor wafer 11, and a head cleaning unit 4b for dressing and cleaning the polishing head 8 A work cleaning unit 5 for cleaning and drying the polished semiconductor wafer 11; a transfer of the semiconductor wafer 11 from the work supply / storage unit 2 to the pre-cleaning unit 3; A first transfer robot (work transfer means) 6 that stores the semiconductor wafer 11 that has been processed and completed in a predetermined position of the work supply storage unit 2; A second transfer robot (work transfer means) 7 for transferring the semiconductor wafer 11 from the pre-cleaning section 3 to the polishing section 4 and transferring the polished semiconductor wafer 11 from the polishing section 4 to the work cleaning section 5. It is comprised including.

The detailed configuration of each part of the polishing apparatus 1 will be described, and each operation of the step of polishing the semiconductor wafer 11 will be described below.

A plurality of semiconductor wafers 11 are loaded into the cassette 1
0 is supplied to the work supply container 2. The first robot 6 operates the cassette 10 by a suction hand (not shown).
The semiconductor wafers 11 are taken out one by one from the semiconductor wafer 11 and transferred to the pre-cleaning section 3. The pre-cleaning unit 3 is provided with a chuck unit 12 that grips the semiconductor wafer 11 and moves up and down. The chuck unit 12 receives the semiconductor wafer 11 transferred from the first transfer robot 6 at the ascending position. Then, the semiconductor wafer 11 held down and held is immersed in the pre-cleaning tank 13. The pre-cleaning tank 13 removes foreign substances attached mainly to the entire back surface of the semiconductor wafer 11 by a cleaning method such as ultrasonic cleaning.
The semiconductor wafer 11 has a thickness of about 500 μm
The semiconductor wafer 11 is deformed due to pressure and friction during polishing even when fine particles such as sliced debris are attached, and the semiconductor wafer 11 has cracks and irregularities. Deformation is formed, which causes a defect. Therefore, the foreign substance is removed by performing the pre-cleaning step in the pre-cleaning section 3, so that it is possible to prevent the occurrence of a defect due to the foreign substance adhered in the polishing step.

The semiconductor wafer 11 which has been completely cleaned by the pre-cleaning section 3 is pre-cleaned by the chuck unit 12 in the pre-cleaning tank 13.
From the suction robot 7 of the second transfer robot 7
a and is transferred onto the polishing stage 9 of the polishing section 4a.

As shown in FIG. 2, the polishing section 4 has a polishing stage 9, a head cleaning tank 14, and a dressing stage 15 arranged in parallel on a table, and is laid along these parallel directions. Drive mechanism (head moving means) 17 on which the polishing head 8 is mounted on the rail 16
Are configured to be able to move linearly. The head drive mechanism 17 is supported on a support table 20 that linearly moves on the rail 16 so that a polishing arm 18 having the polishing head 8 mounted thereon can move up and down. Therefore, the polishing head 8
Is rotatably driven by a motor mounted on the polishing arm 18, and can move up and down and move horizontally.
Further, the periphery of the polishing stage 9 is surrounded by a shielding cover (shielding means) 19, and a shielding lid (shielding means) 21 attached to the polishing arm 18 can close an upper opening of the shielding cover 19 during polishing. It is configured as follows.

When the semiconductor wafer 11 is transferred onto the polishing stage 9 by the second transfer robot 7,
The support 20 has been moved to a position where the polishing stage 9 is open, and when the semiconductor wafer 11 is transferred onto the polishing stage 9, the support 20 moves the polishing head 8 above the polishing stage 9. , And lowers the polishing arm 18 to move the polishing head 8 to the semiconductor wafer 11.
The upper part is brought into contact with a predetermined pressure. The polishing of the surface of the semiconductor wafer 11 is performed by supplying a polishing liquid between the surface of the semiconductor wafer 11 and the polishing head 8 and the relative rotation between the rotation of the polishing head 8 and the rotation of the polishing stage 9. At this time,
Since the upper opening of the shielding cover 19 is closed by the shielding lid 21 when the polishing arm 18 is lowered, the polishing liquid and the like do not scatter around during polishing.

When the polishing is completed, the polishing arm 18 is raised, and the support table 20 is moved, so that the polishing head 8 and the shielding lid 21 are retreated from above the polishing stage 9. The semiconductor wafer 11 is held and transferred to the work cleaning section 5. Work cleaning section 5
Is configured to include a work support (centrifugal dehydrating means) 22 that is driven up and down and rotated and a brush cleaning unit 23, and the semiconductor wafer 11 is placed on the work support 22.
When the semiconductor wafer 11 is transferred, the semiconductor wafer 11 is held and lowered, and the semiconductor wafer 11 is moved to the position where the brush cleaning unit 23 is disposed. The semiconductor wafer 11 is cleaned by the rotation of the work support base 22 and the rotation of the brush while the cleaning water is supplied,
The remaining polishing liquid and polishing residue are removed. When the cleaning is completed, the work support 22 rotates at a high speed to dry the semiconductor wafer 11 by centrifugal dehydration. The work supporting table 22 holding the dried semiconductor wafer 11 rises, and the first transfer robot 6 moves the semiconductor wafer 1 by the suction hand.
The semiconductor wafer 11 is accommodated in a predetermined position of the work supply accommodating section 2 while holding the back surface of the semiconductor wafer 11 by suction.

On the other hand, the polishing head 8 which has finished polishing the semiconductor wafer 11 in the polishing section 4a,
Moves above the dressing stage 15 of the head cleaning section 4b. The polishing head 8 that has been lowered onto the dressing stage 15 by the lowering of the polishing arm 18 is subjected to a dressing process for shaping the turbulence of the polishing surface by the dressing stage 15,
The polishing head 8 is moved to the head cleaning tank 1 by the movement of the support table 20.
Move up 4. The head cleaning tank 14 is provided with an ultrasonic oscillator on its bottom surface and is configured to vibrate the cleaning liquid filled in the tank with ultrasonic waves. When immersed in the cleaning solution,
Foreign substances such as polishing liquid and polishing residue adhering to the polishing head 8 are removed by ultrasonic cleaning. Since the semiconductor wafer 11 to be polished next is transferred onto the polishing stage 9 during the dressing and cleaning of the polishing head 8, the polishing head 8 is moved on the polishing stage 9 by the movement of the polishing arm 18 and the support table 20. To perform the polishing operation. As described above, the polishing head 8 is subjected to dressing and cleaning by the head cleaning unit 4b every time polishing is completed, so that the polishing head 8 is always maintained in a constant state and can perform stable polishing. Can be maintained.

In the above configuration, when the temperature of the polishing head 8 rises due to friction caused by polishing, the polishing rate changes due to this temperature change, making it difficult to maintain a constant polishing state.

In order to prevent the temperature of the polishing head 8 from rising and to keep the temperature constant, the polishing head 8 may be provided with a temperature control structure as shown in FIG.

As shown in FIG. 3, the polishing head 8 is formed in a hollow shape, and an air supply cylinder 25 and an exhaust cylinder 26 as fluid circulating means are arranged concentrically about a rotation drive shaft 8a of the polishing head 8. And an intake pipe 25 and a temperature control device (temperature control means) 24 are connected by an air supply pipe 28 so that the exhaust pipe 2
6 and the temperature control device 24 are connected by an exhaust pipe 29. While the polishing operation is being performed by the polishing head 8, the temperature controller 24 circulates air through the air supply cylinder 25 and the exhaust cylinder 26 and detects the air temperature. The air supply is controlled so that the air temperature at the time when the air supply is in the range. With this configuration, the temperature of the polishing head 8 is maintained in a constant state, and the polishing rate does not change. Therefore, the polishing state controlled by the polishing time is maintained in a constant state.

The shielding cover 1 surrounding the polishing stage 9
9 can be configured by connecting a suction pump 27 as shown in FIG. When the upper opening of the shielding cover 19 is closed by the shielding lid 21 at the time of polishing, the air in the space closed by the shielding cover 19 and the shielding lid 21 is sucked by the suction pump 27 so that polishing is performed. The scattering of the liquid and the like is more effectively suppressed, and the mist of the polishing liquid and the air in which the abrasive particles float in the enclosed space are sucked out by the suction pump 27, and the scattering to the outside is suppressed, and at the same time, the air in the enclosed space is suppressed. Dirt is suppressed. As described above, the configuration in which the periphery of the polishing stage 9 is shielded so as to prevent scattering of the polishing liquid or the like and suction of a type such as a scattering mistake can be performed, so that the polishing process can be arranged in a small installation space. Can be reduced in size.

Although the above-described polishing apparatus has been described as being configured to polish the surface of the semiconductor wafer 11, the polishing apparatus can be similarly applied to polishing a thin plate-like work such as a liquid crystal substrate.

[0037]

As described above, according to the present invention, dressing and cleaning of the polishing head are performed during the replacement of the work on the polishing stage, and the polishing is performed by the polishing head which is always maintained. Since the temperature of the polishing head can be kept constant, the polishing state is stable, and high quality polishing is always performed. Also,
Since the shielding cover and the shielding lid for preventing the scattering of the polishing mist in the polishing process are provided, the polishing mist does not adversely affect other components even if the polishing part is configured in the minimum space, and the size of the apparatus can be reduced. Can be planned. In addition, by cleaning the work to be polished in advance, it is possible to prevent occurrence of poor polishing due to foreign matter attached to the work. In addition, since the work after polishing is washed and dried, it can be finished in a state in which the polishing liquid and the polishing residue have been removed.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration of a polishing apparatus according to an embodiment.

FIG. 2 is a perspective view showing a configuration of a polishing section according to the embodiment.

FIG. 3 is a schematic view showing an example of a temperature control structure of the polishing head.

FIG. 4 is a schematic diagram showing a configuration example in which a polishing error is sucked from a shielding space in a polishing stage portion.

FIG. 5 is a plan view showing a configuration of a polishing apparatus according to a conventional configuration.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Polishing apparatus 2 Work supply accommodating part 3 Pre-cleaning part 4 Polishing part 4a Polishing part 4b Head cleaning part 5 Work cleaning part 6 First transfer robot (Work transfer means) 7 Second transfer robot (Work transfer) Mounting means) 8 polishing head 9 polishing stage 11 semiconductor wafer (work) 14 head cleaning tank 15 dressing stage 17 head driving mechanism (head moving means) 19 shielding cover (shielding means) 21 shielding lid (shielding means) 22 work support base ( Centrifugal dewatering means) 23 brush cleaning unit 24 temperature control device (temperature control means) 25 air supply cylinder (fluid circulation means) 26 exhaust pipe (fluid circulation means) 27 suction pump (mist suction means)

Claims (10)

[Claims] In a polishing method for polishing a surface of a work formed in a thin plate shape, the work is transferred onto a polishing stage, and after finishing a polishing step of polishing the surface of the work by a polishing head, The work is transferred to a work cleaning step for cleaning and drying, and the polishing head performs a series of operations for moving to a head cleaning step for dressing and cleaning for each polishing process on each work. Characteristic polishing method. 2. The polishing method according to claim 1, wherein a pre-cleaning step of cleaning the work is performed before transferring to the polishing step. 3. The polishing method according to claim 1, wherein the polishing step is performed in a closed space surrounding the polishing stage and the polishing head. 4. A polishing apparatus for polishing a surface of a work formed in a thin plate shape, a work supply unit for supplying a work to be polished, and a polishing head for polishing the surface of the work disposed on a polishing stage. A polishing section, a head cleaning section including a dressing stage for dressing the polishing head after polishing the work, and a head cleaning tank for cleaning the polishing head, and washing and drying of the polished work A work cleaning unit to be cleaned, a work storage unit for storing the cleaned and dried work, and a work transfer for transferring the work one by one from the work supply unit to the polishing processing unit, the work cleaning unit, and the work storage unit. Means, and a head moving means for moving the polishing head between a polishing section and a head cleaning section. Polishing apparatus. 5. The polishing apparatus according to claim 4, further comprising a pre-cleaning section for cleaning the work taken out from the work supply section before transferring the work to the polishing section. 6. The polishing apparatus according to claim 4, wherein the polishing section is provided with shielding means for covering the periphery of the polishing stage and the polishing head when polishing is performed. 7. The polishing apparatus according to claim 6, further comprising an air suction means for discharging the air surrounded by the shielding means. 8. The polishing apparatus according to claim 4, wherein the head cleaning tank is provided with an ultrasonic cleaning means. 9. The polishing apparatus according to claim 4, wherein the polishing head is provided with a fluid circulating means for circulating a fluid in the polishing head and a temperature adjusting means for adjusting the temperature of the fluid. 10. The polishing apparatus according to claim 4, wherein the work cleaning unit is provided with a cleaning brush for cleaning the work and a centrifugal dewatering means for scattering water adhering to the work.