JP2002237477A - Method of polishing work and polishing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure the favorable polished surface of a work and to raise the yield of the manufacture of the work without leaving particles on the work. SOLUTION: A method of polishing the work (wafer) 5 brings the work 5 held by a work holder 6 into contact with a polishing pad 7 translating for an orbital motion while the work 5 is rotated to polish the work 5. The method is provided with a process for dyeing a slurry from the pad 7, a process for polishing the work 5 under the interposition of the slurry, a process for dyeing pure water from the pad 7 to substitute the pure water for the slurry, and a process for polishing the work 5 under the interposition of the pure water.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method and an apparatus for polishing a work such as a semiconductor wafer.

[0002]

2. Description of the Related Art FIG. 7 shows a conventional semiconductor wafer polishing apparatus. The method of polishing a wafer by this polishing apparatus is roughly as follows. First, the wafer 101 a stored in the wafer cassette 101 is transferred to the transfer unit 103 by the dry robot 102. Next, the dry robot 10
2, the wafer 101a is transferred to the wafer holder 104. While rotating the wafer holder 104 holding the wafer 101a, the pad holder 106 on which the polishing pad 105 is mounted is lowered while rotating, and the wafer 10
1a. In this state, the pad holder 106 is
The wafer is polished by the polishing pad 105 while the slurry is supplied from the slurry supply nozzle 107 while being reciprocated in the axial direction.

After polishing, the pad holder 106 is raised, and the wafer is transferred from the wafer holder 104 to the cleaning section 109 by the wet robot 108. Then, the wafer is cleaned and dried by the cleaning unit 109, and the wafer is stored in the wafer cassette 101 by the dry robot 102.

On the other hand, the pad holder 106 is
In this dress section 110, the dress 111 is rotated, and the pad holder 106 is lowered while rotating so as to contact the dress 111. In this state, the pad holder 106 is reciprocated in the X-axis direction to dress the polishing pad 105 with the dress 111. After the dressing is completed, the pad holder 106 is raised and returned on the wafer holder 106 to prepare for the next polishing.

[0005]

However, in the above-mentioned conventional polishing method, there is a problem that the wafer surface is corroded by a chemical reaction with the polishing liquid after polishing, or particles of the polishing liquid remain on the work after polishing and cleaning. Was.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and provides a polishing method and a polishing apparatus capable of securing a good polished surface, leaving no particles on a work, and improving the yield. The task is to provide.

[0007]

As a means for achieving the above object, a polishing method according to the present invention is a polishing method for polishing a work by rotating a work held by a work holder and bringing the work into contact with a polishing pad which translates and revolves. In the polishing method, the step of extruding the slurry from the polishing pad, the step of polishing the work with the intervention of the slurry, the step of extruding pure water from the polishing pad and replacing the slurry with the slurry, Polishing step.

According to the present invention, after the slurry is polished, the slurry is replaced with pure water and the water is polished, so that the wafer surface does not corrode due to the chemical reaction by the slurry after the polishing, and the particles of the slurry remain. Not even.

In the present invention, a step of supplying pure water to the work while transferring the work to a work cleaning section for cleaning the polished work so that the polished work is not exposed to the atmosphere for a predetermined time or more. More preferably, it has.

In the present invention, the step of removing the polished work from the work holder and then transferring and holding the dress plate on the work holder, and the step of translating and revolving while rotating the dress plate held by the work holder. And dressing the polishing pad by bringing the polishing pad into contact with the polishing pad. Thereby, the dressing of the polishing pad can be performed in the same manner as the polishing of the work. In this case, in order to efficiently clean the dress plate, the method may further include a step of removing the dress plate from the work holder and transferring the dress plate to the dress plate cleaning unit, and a step of cleaning the dress plate by the dress plate cleaning unit. preferable. It is preferable that the method further includes a step of ejecting the high-pressure liquid to the polishing pad after dressing the polishing pad with the dress plate. Thereby, it is possible to prevent the falling off abrasive grains or debris floating or fixed on the polishing pad after the dressing from remaining, thereby preventing a defect such as a scratch from occurring in the work in the next polishing process.

As a means for achieving the above object, a polishing apparatus according to the present invention is a polishing apparatus for polishing a work held in contact with a polishing pad which translates and revolves while rotating a work held by a work holder. A means for discharging the slurry from the polishing pad and a means for discharging the pure water from the polishing pad are provided.After polishing the work with the slurry interposed, the slurry is replaced with pure water, and the work is formed with the pure water interposed. It is intended to be polished.

In the present invention, it is preferable that the apparatus further includes a pure water supply means for cleaning the polished work and supplying pure water to the work while transferring the work to the work cleaning section.

Further, in the present invention, a dress plate mounting portion for mounting a dress plate having the same shape as a workpiece, and a dress plate transferring device for transferring a dress plate between the dress plate mounting portion and the work holder. It is preferable that a polishing pad be dressed by rotating the dress plate held by the work holder and bringing the polishing pad into contact with the revolving polishing pad while rotating. In this case, it is preferable that a dress plate cleaning unit for cleaning the dress plate is further provided in a moving range of the dress plate transfer unit. Further, it is preferable to provide a high-pressure nozzle for ejecting a high-pressure liquid to the polishing pad.

[0014]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows a polishing apparatus according to the present invention.
This polishing apparatus generally includes a polishing module 1, a dry transfer module 2, a wet transfer module 3, and a cleaning / drying module 4.

The polishing module 1 is, as shown in FIG.
Work holder 6 for sucking and holding wafer 5 as a work
And a translation revolving plate 8 provided with a polishing pad 7 so as to face the work holder 6. The work holder 6 is attached to the lower end of a spindle 12 rotatably provided at the tip of a lifting block 11 extending horizontally from a column section 10 of a machine base 9. The translation revolving plate 8 has a thrust fluid bearing 1 on a base 9.
3, and both ends are supported via bearings 16 on two crankshafts 15 that are rotatably supported on the base 9 in the vertical direction via bearings 14. A motor 17 is connected to one of the crankshafts 15, so that the translation revolving plate 8 performs a translation revolving motion in a horizontal plane.

A polishing pad 7 is provided on the upper surface of the translation revolution plate 8. Below the polishing pad 7, a slurry supply pipe 18 for exuding slurry from the surface of the polishing pad 7 and a pure water supply pipe 19 for exuding pure water from the surface of the polishing pad 7 are provided. . Polishing pad 7
A flexible corrugated ring 20 is provided between the peripheral edge of the thrust bearing 13 and the thrust bearing 13 so that slurry or pure water oozing from the polishing pad 7 does not enter the inside.

As shown in FIG. 1, around the polishing module 1, a temporary wafer placement section 21, a wafer reversing section 22, and a wafer 5 between the temporary wafer placement section 21 and the work holder 6.
And a wafer transfer arm 23 for performing the transfer. Further, a dress plate 24 having the same shape as that of the wafer 5 is placed and a dress plate placing / cleaning unit 25 for cleaning the dress plate 24 is provided between the dress plate placing / cleaning unit 25 and the work holder 6. Dress plate transfer arm 26 for transferring dress plate 24
And are arranged. Further, a high-pressure jet supply pipe 27 having a high-pressure jet nozzle 27a for supplying a high-pressure jet to the polishing pad 7 and being movable between a supply position above the polishing pad 7 and a retracted position retracted from the polishing pad 7 is arranged. ing.

The dry transfer module 2 comprises a wafer supply unit 28 for supplying the wafers 5 from the cassette, a wafer position regulating unit 29, a dry robot 30, and a wafer receiving unit 31 for receiving the wafers 5 in the cassette.
The dry robot 30 is movable between the wafer supply unit 28 and the wafer position regulating unit 29 and between a cleaning transfer unit 39 of the cleaning / drying module 4 described later and the wafer receiving unit 31. The wafer 5 is transferred from the section 28 to the wafer position regulating section 29, and the wafer 5 is transferred from the cleaning transfer section 39 of the cleaning / drying module 4 to the wafer receiving section 31.

The wet transfer module 3 has a first position close to the wafer position regulating unit 29, a second position close to the temporary wafer placement unit 21, and a positioning unit 34 of the cleaning / drying module 4 described later. And a wet robot 32 that can reciprocate between the third position. The wet robot 32 grasps the wafer 5 of the wet position regulating unit 29 at the first position, transfers the wafer 5 to the wafer temporary storage unit 21 at the second position, and transfers the wafer 5 from the work holder 6 to the wafer temporary storage unit 21. The transferred wafer 5 is gripped, and the wafer 5 is transferred to the transfer mechanism 33 of the cleaning / drying module 4 at the third position.

The cleaning / drying module 4 has a transfer mechanism 33 that grips the wafer 5 and moves in the direction of the arrow, and the positioning unit 34 and the ammonia cleaning unit 35 along the transfer direction of the wafer 5 by the transfer mechanism 33. , A plurality of hydrofluoric acid cleaning units 36, a pure water megasonic cleaning unit 37, a drying unit 38, and a cleaning transfer unit 39.

The range of movement of the wafer transfer arm 23 of the polishing module 1 and the range of movement of the wet robot 32 of the cleaning / drying module 4 include a pure water supply nozzle 40 for applying pure water to the moving wafer 5. Are arranged at appropriate positions.

Next, a method of polishing the wafer 5 using the polishing apparatus having the above-described configuration will be described with reference to the flowcharts of FIGS.

The wafer 5 stored in the cassette of the wafer supply unit 28 is taken out by the dry robot 30 (step 101) and transferred to the wafer position regulating unit 29 (step 102). The wafer 5 of the wafer position regulating unit 29 is
It is gripped by the wet robot 32 at the first position, and is transferred to the temporary wafer placement unit 21 at the second position (step 10).
3) Here, after being inverted by the wafer inverting unit 22 (Step 104), the wafer is transferred to the work holder 6 by the wafer transfer arm 23 (Step 105) and sucked.

Then, the lifting block 11 is lowered (Step 106), and the wafer 5 is brought into contact with the polishing pad 7 to start polishing (Step 107). In the polishing step, the slurry is exuded from the polishing pad 7 by the slurry supply pipe 18 (Step 201). When the slurry has sufficiently spread between the wafer 5 and the polishing pad 7, the spindle 12 is driven to move the work holder 6 to the work holder 6. The translation orbiting plate 8 is caused to translate and revolve while rotating (step 20).
2). Thus, the wafer 5 is polished by the polishing pad 7 with the slurry interposed. During polishing, the polishing temperature is kept constant by adjusting the slurry flow rate, the pressing force of the wafer 5 against the polishing pad 7, the number of rotations of the wafer 5, and the translation revolution period of the translation revolution plate 8. The particles of the slurry that bind to the surface of the wafer 5 due to the chemical reaction are mechanically removed by the polishing pad 7.

When the polishing of the slurry is completed, the supply of the slurry is stopped, and pure water is exuded from the polishing pad 7 by the pure water supplier 19 to replace the slurry (step 20).
3) The slurry concentration is reduced to a predetermined concentration in about 6 seconds. Then, while rotating the work holder 6 again, the translation revolving plate 8 is caused to translate and revolve, and the wafer 5
Is polished by the polishing pad 7 with pure water interposed (step 204). By this water polishing, particles of the slurry remaining on the wafer surface are mechanically removed.

When the water polishing is completed, the lifting block 11 is raised (Step 108), and the wafer 5 is transferred to the temporary wafer placement section 21 by the wafer transfer arm 23 (Step 1).
09) Here, the wafer 5 is inverted by the wafer inverting unit 22 (Step 110). Then, the wafer 5 is gripped by the wet robot 30, moved from the second position to the third position, transferred to the transport mechanism 33 of the cleaning / drying module 4 (Step 111), and cleaning is started (Step 112). ). After the polishing, until the wafer 5 is transferred to the transport mechanism 33, the pure water supply nozzle 40 is used to prevent the remaining slurry from being exposed to the atmosphere for 3 seconds or more and sticking to the wafer surface. More pure water is supplied to the moving wafer 5.

In the cleaning step, first, the wafer 5 gripped by the arm of the transport mechanism 33 is positioned by the positioning section 34, and then transported to the cleaning sections 35, 36, 37 sequentially. In the ammonia cleaning section 35, ammonia cleaning is performed using alkaline ammonia water (step 301), the zeta potential on the wafer surface is lowered, particles floating on the wafer surface are easily floated, and the ammonia water flow and brush are used. Particles are removed from the surface of the wafer 5. Subsequently, in the hydrofluoric acid cleaning section 36, hydrofluoric acid cleaning is performed using hydrofluoric acid water (step 302), and the slurry and metal ions fixed on the surface of the wafer 5 are released by etching the wafer surface. The particles are removed from the surface of the wafer 5 by a flow of hydrofluoric acid and a brush. Furthermore, pure water megasonic cleaning section 3
At 7, pure water megasonic cleaning is performed using pure water and megasonic (step 303), and the surface of the wafer 5 is vibrated and cleaned to remove particles attached to the surface of the wafer 5. And finally, in the drying unit 38,
By blowing nitrogen gas onto the wafer 5 and rotating the wafer 5 at high speed, pure water is removed from the surface of the wafer 5 and dried (step 304). The dried wafer 5 is transferred from the drying unit 38 to the cleaning transfer unit 39 by the transfer mechanism 33,
The wafer is stored in the wafer receiving unit 31 by the dry robot 30 (step 113).

On the other hand, in the polishing module 1, pure water is supplied to the work holder 6 through the pure water supply pipe 19 so that the slurry attached to the work holder 6 during polishing is not dried and fixed (step 114). Next, the dress plate 24 of the dress plate mounting / washing unit 25 is transferred to the work holder 6 by the dress plate transfer arm 26 (step 115), and is held here by suction. Then, the elevating block 11 is lowered (step 116), and the dress plate 2
The polishing pad 7 is dressed by a dress plate by bringing the translation contact plate 4 into contact with the polishing pad 7 and rotating the translation revolving plate 8 while rotating the work holder 6 in the same manner as during polishing (step 117). Thereby, while removing the surface layer of the polishing pad 7 whose physical properties have changed due to the temperature, pressure, and chemical reaction during polishing, the porous surface of the polishing pad 7 is exposed to the surface of the polishing pad 7 and activated. The surface of the polishing pad 7 is smoothed, and the polishing pad 7 is restored to the initial state.

After the dressing, the dress plate 24 of the work holder 6 is transferred to the dress plate mounting / washing section 25 by the dress plate transfer arm 26 (step 11).
8) Wash the dress plate 24 to prepare for the next dress. Further, the high-pressure jet supply pipe 27 is moved onto the dressed polishing pad 7, and a high-pressure jet is jetted from the high-pressure jet nozzle 27a (step 11).
9) Removed abrasive grains and debris floating or fixed on the polishing pad 7 after dressing to prevent scratches from occurring on the surface of the wafer 5 in the next polishing. After the high-pressure jet cleaning, the high-pressure jet supply pipe 27 is retracted from the polishing pad 7, and the next polishing is started.

[0031]

As is clear from the above description, according to the present invention, after polishing the slurry, the slurry is replaced with pure water and water polishing is performed. There is no corrosion and no slurry particles remain. As a result, the product yield is improved.

[Brief description of the drawings]

FIG. 1 is a plan view of a polishing apparatus according to the present invention.

FIG. 2 is a perspective view of the polishing apparatus of FIG.

FIG. 3 is a partially broken front view of the polishing module.

FIG. 4 is a flowchart showing all polishing steps.

FIG. 5 is a flowchart of a polishing subroutine.

FIG. 6 is a flowchart of a cleaning subroutine.

FIG. 7 is a plan view of a conventional polishing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Polishing module 2 Dry transfer module 3 Wet transfer module 4 Washing and drying module 5 Wafer 6 Work holder 7 Polishing pad 18 Slurry supply pipe 19 Pure water supply pipe 25 Dress plate transfer arm 27 High pressure jet supply pipe 40 Pure water supply nozzle

Claims (10)

[Claims] 1. A polishing method for polishing a work by rotating a work held by a work holder and bringing the work into contact with a polishing pad revolving and revolving, wherein a step of discharging a slurry from the polishing pad; A polishing method comprising: a step of polishing with a polishing pad; a step of exuding pure water from a polishing pad to replace the slurry; and a step of polishing a workpiece with pure water. 2. The polishing method according to claim 1, further comprising a step of supplying pure water to the workpiece while transferring the workpiece to a workpiece cleaning section for cleaning the polished workpiece. 3. A step of removing a polished work from a work holder, transferring a dress plate to the work holder and holding the dress plate, and a step of rotating the dress plate held by the work holder and revolving the polishing pad. 3. The polishing method according to claim 1, further comprising a step of dressing the polishing pad by contacting the polishing pad. 4. The method according to claim 3, further comprising: removing the dress plate from the work holder and transferring the dress plate to the dress plate cleaning unit; and cleaning the dress plate by the dress plate cleaning unit. Polishing method. 5. The polishing method according to claim 3, further comprising a step of ejecting a high-pressure liquid to the polishing pad after dressing the polishing pad with the dress plate. 6. A polishing apparatus for polishing a work by rotating a work held by a work holder and bringing the work into contact with a polishing pad which is revolved and revolved, comprising: means for discharging slurry from the polishing pad; and pure water from the polishing pad. A polishing apparatus comprising: a means for exuding water; polishing the work with the intervention of slurry; replacing the slurry with pure water; and polishing the work with the intervention of pure water. 7. The polishing apparatus according to claim 6, further comprising pure water supply means for supplying pure water to the workpiece while transferring the workpiece to a workpiece cleaning section for cleaning the polished workpiece. . 8. A dress plate mounting portion for mounting a dress plate having the same shape as a workpiece, and a dress plate transferring means for transferring a dress plate between the dress plate mounting portion and the work holder. The polishing apparatus according to claim 6, wherein the polishing pad is dressed by rotating the dress plate held by the work holder and bringing the polishing pad into contact with a translationally revolving polishing pad. 9. The polishing apparatus according to claim 8, further comprising a dress plate cleaning unit for cleaning a dress plate, in a moving range of the dress plate transfer unit. 10. The polishing apparatus according to claim 8, further comprising a high-pressure nozzle for jetting a high-pressure liquid to the polishing pad.