KR20100040056A - Apparatus for polishing wafer - Google Patents

Abstract

PURPOSE: An apparatus for polishing a wafer is provided to improve the quality of wasted abrasives by recovering the concentration and the size of the wasted abrasives into an initial state of abrasives. CONSTITUTION: A polishing unit(10) polishes a wafer(W) with an abrasive(S1). A supplying unit(20) supplies the abrasive to the polishing unit. A recycling unit(30) recovers the concentration and the size of the wasted abrasive into an initial state. The recovered abrasive is supplied to the supplying unit. The recycling unit includes a collection container, an ultrasonic part, a filter part and a recycling part.

Description

Wafer Polishing Machine {APPARATUS FOR POLISHING WAFER}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer polishing apparatus, and more particularly, to a wafer polishing apparatus capable of collecting and recycling waste abrasives used for polishing a wafer, and a recycling method thereof.

Silicon wafers that are widely used as materials for manufacturing semiconductor devices today refer to crystalline silicon thin films made of polycrystalline silicon as a raw material.

The shaping process for manufacturing a wafer includes a slicing process for cutting grown silicon single crystal ingots into wafer form, a lapping process for uniformizing and planarizing the thickness of the wafer, and mechanical polishing. An etching process for removing or mitigating damage generated, a polishing process for mirror-mirroring the wafer surface, and a cleaning process for cleaning the polished wafer and removing foreign matter adhered to the surface.

Due to the high integration of semiconductor devices, lapping and chemical mechanical polishing processes in semiconductor wafer manufacturing processes are important to have a great effect on device yield and productivity in semiconductor manufacturing processes such as flatness, scratches and defects of semiconductor wafers. It is recognized as one of the arguments.

Chemical mechanical polishing (CMP) provides a wafer comprising a slurry consisting of abrasive particles and various chemical liquids, and the surface of the wafer by chemical reaction between the slurry and the wafer and mechanical action of the abrasive particles and the polishing pad. Remove the irregularities of the flattening. Here, after the polishing process of the wafer, a rinsing process for removing the slurry remaining on the surface of the wafer and the polishing pad is performed.

On the other hand, the polishing process of the wafer polishing apparatus can be divided into a stock polishing process for removing the altered layer on the wafer surface and improving the thickness uniformity of the entire wafer, and a final polishing process for processing the surface roughness to a mirror surface of 1 A or less. In the stock polishing process and the final polishing process, a slurry of 40 to 150 L is usually used by simultaneously polishing a plurality of wafers at a time. In order to solve the cost problem of using such a large amount of slurry, the slurry used for stock polishing is recycled.

In order to recycle the slurry, as shown in FIG. 1, the waste slurry used from the polishing unit 10 is collected into the supply tank 20, the pH is adjusted, and then filtered through the filter 30 and reused. However, when the waste slurry is recycled in this way, impurities in the polishing pad and wafer and agglomerates of the slurry are generated during the polishing process, and weak agglomeration of the abrasive particles by shear force occurs during the circulation of the slurry. As a result, the number of large particles is increased. Such impurities and large particles of the slurry cause scratches on the surface of the wafer to be polished upon reuse, and act as a factor that hinders the circulation of the polishing pad and the residual slurry on the wafer surface. In addition, when the aggregated large particles are filtered by the filter 30, the concentration of the slurry is reduced to lower the polishing rate.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a polishing apparatus for a wafer capable of improving the quality of the waste abrasive used in the polishing process.

Another object of the present invention is to provide an apparatus for polishing a wafer, in which both the waste abrasive and the pure water as a cleaning liquid can be discharged with one discharge pipe, and the waste abrasive can be easily recycled.

A wafer polishing apparatus for achieving the above object includes a polishing unit for polishing a wafer by an abrasive, a supply unit for supplying an abrasive to the polishing unit, and a concentration and size of waste abrasive used in the polishing unit. After compensating for the initial state, and comprises a recycling unit for supplying to the supply unit.

According to one embodiment of the invention, the recycling unit, the waste container is collected, the ultrasonic unit is installed in the collection, the ultrasonic unit for generating an ultrasonic wave for releasing the cohesive force of the collected waste abrasive, the container and the It is provided between the supply unit, and the filter unit for filtering the waste abrasive, and the regeneration unit for regenerating the waste abrasive before the filtered waste abrasive is introduced into the supply unit.

Here, the filter unit includes a plurality of filter members for simultaneously filtering the waste abrasive discharged from the sump, and a waste abrasive pump for supplying the waste abrasive to the supply unit is provided at the outlet side of the sump.

The recycling unit of the recycling unit, the large particle measuring unit for measuring the size of the waste abrasive, the concentration meter for measuring the concentration of the waste abrasive, and based on the information measured from the large particle meter and the concentration meter, Compensation unit for compensating the size and concentration. In this case, the compensator supplies an abrasive in which the stock solution and / or pure water of the abrasive is mixed to the supply unit.

By the construction of the recycling unit, the waste abrasive is compensated to its initial state before being used in the polishing process and can be reused in the polishing process of the wafer.

On the other hand, the supply unit includes a supply cylinder in which the abrasive to be supplied is accommodated, a supply filter provided at the outlet side of the supply cylinder to filter the abrasive, and a supply nozzle to supply the filtered abrasive to the polishing unit. . Here, a supply pump for supplying the abrasive to the supply filter side is provided on the outlet side of the supply cylinder.

The polishing unit may further include a surface plate having a polishing pad, a polishing head for pressing the wafer against the polishing pad, and a pure water for supplying pure water for cleaning the polishing pad and the wafer after the polishing process of the wafer. And a supply member, a receiving member for collecting waste abrasive and pure water used during the polishing and cleaning process of the wafer, and a discharge part for discharging the waste abrasive and pure water collected in the receiving member.

Here, the discharge portion, the main discharge pipe connected to the receiving member, the sub discharge pipe for interconnecting the main discharge pipe and the recycling unit, and a control valve for moving only the waste abrasive to the sub discharge pipe side between the main and sub discharge pipes; It includes.

According to another aspect of the present invention, there is provided a polishing apparatus for a wafer, comprising: a polishing unit for polishing a wafer with an abrasive and cleaning with a cleaning agent; a supply unit for supplying the abrasive to the polishing unit; And a recycling unit for recycling the waste abrasive used in the polishing unit by measuring the size and compensating for the state before the polishing process, and then moving to the supply unit, wherein the waste abrasive and the cleaning agent discharged from the polishing unit are one. After discharged through the discharge pipe of the, characterized in that only the waste abrasive is moved to the recycling unit side. With this configuration, it is possible to improve the problem that the waste abrasive is dried in the discharge pipe and contaminates a subsequent polishing process.

According to the present invention having the above-described configuration, first, by collecting the waste abrasive that has already been used for polishing the wafer, grasping the state of the waste abrasive and compensating for it, thereby improving the quality of the waste abrasive used for polishing the wafer. You can do it.

Second, by being able to reuse high-quality waste abrasive, it is possible to reduce the amount of abrasive used in the polishing process. This makes it possible to implement high quality wafer polishing apparatus at low cost.

Third, the waste abrasive polished wafer and the pure water cleaned wafer can be discharged through a single discharge pipe, so that the conventional problems that the waste abrasive is dried and dried in the discharge pipe during the cleaning process by pure water can be improved. do.

Hereinafter, a preferred embodiment of the present invention will be described with reference to the accompanying drawings.

Referring to FIG. 2, a wafer polishing apparatus 1 according to an embodiment of the present invention includes a polishing unit 10, a supply unit 20, and a recycling unit 30.

The polishing unit 10 polishes the surface of the wafer W to mirror its surface. The polishing unit 10 includes a surface plate 11, a polishing head 13, a pure water supply unit 14, a receiving member 15, a discharge unit 16, and the like.

The surface plate 11 is rotated with the polishing pad 12. For this purpose, the surface plate 11 is connected to a driving unit, not shown, which can be understood from a known technique, and thus, the detailed description and illustration are shown. Omit.

The polishing pad 12 provided on the surface plate 11 is a mechanical polishing element that is in direct contact with the wafer W to selectively planarize by selectively removing protrusions among the irregularities on the wafer W. In more detail, the polishing pad 12 has fine protrusions or grooves having various shapes in order to increase planarization efficiency, thereby polishing the surface of the wafer W by friction with the wafer W. .

On the other hand, the abrasive S1, which is a chemical polishing element, is supplied onto the wafer W that is mechanically polished by the contact with the polishing pad 12. Here, the abrasive (S1) is to polish the wafer (W) through a chemical reaction on the surface of the wafer (W), in a sol (Sol) state containing abrasive particles such as colloidal silica (Colloidal Silica) Slurry, which is a suspension. The abrasive S1 is provided between the grooves provided in the polishing pad 12. Therefore, as the abrasive S1 is supplied while the wafer W and the polishing pad 12 are rotated while being pressed, the wafer W is mechanically and chemically polished.

For reference, the polished wafer W is exemplified as a silicon wafer that is a raw material of a silicon semiconductor substrate, but is not limited thereto.

The polishing head 13 is pressed toward the surface plate 11 to press the wafer W toward the polishing pad 12. In addition, the polishing head 13 is connected and rotated by a rotating means not shown. At this time, the polishing head 13 is rotated while pressing the polishing pad 12 toward the wafer (W) side, the wafer (W) is rotated.

The pure water supply unit 14 supplies pure water DI for removing the wafer W polished by the abrasive S1 and the waste abrasive S2 remaining on the polishing pad 12 onto the wafer W. do. That is, the pure water supply unit 14 supplies pure water DI, which is a cleaning agent used in a cleaning process for cleaning the components used in the polishing operation, such as the wafer W and the polishing pad 12 after the polishing process. will be.

The receiving member 15 collects the waste abrasive S2 and the pure water, which have been used for polishing and cleaning the wafer W. The receiving member 15 has a donut shape facing the outer peripheral portion of the surface plate 11 at the lower portion of the surface plate 11 for easy collection of the waste abrasive S2 flowing out from the outer surface portion of the surface plate 11 and pure water. It is good to install with.

The discharge unit 16 discharges the waste abrasive (S2) and the pure water collected in the receiving member 15 to the outside of the receiving member 15, thereby the main discharge pipe 17, the sub discharge pipe 18 and the adjustment Valve 19.

The main discharge pipe 17 is connected to the receiving member 15 to discharge both the waste abrasive S2 and pure water. The sub discharge pipe 18 interconnects the main discharge pipe 17 and the recycling unit 30 to be described later, and transfers only the waste abrasive S2 to the recycling unit 30. The control valve 19 selectively opens and closes the sub discharge pipe 18 to move only the waste abrasive S2 to the sub discharge pipe 18 side between the main and sub discharge pipes 17 and 18.

According to this configuration, after the waste abrasive used during the polishing process of the wafer W by the polishing unit 10 is discharged through the main discharge pipe 17, the recycling unit 30 is opened by opening the control valve 19. It can flow into the side. In addition, after the polishing process by the polishing unit 10, the pure water supplied from the pure water supply unit 14 is discharged through the main discharge pipe 17 after cleaning the wafer (W) and the polishing pad 12, The waste abrasive S2 remaining in the main discharge pipe 17 can also be discharged together. Therefore, it is possible to improve the conventional problems caused by the residual abrasive S2 remaining in the main discharge pipe 17 and drying.

The supply unit 20 supplies the abrasive S1 to be used in the polishing process to the polishing unit 10. To this end, the supply unit 20 includes a supply cylinder 21, a supply filter 25 and a supply nozzle 26.

The supply cylinder 21 accommodates the abrasive S1 to be supplied, and has an inlet pipe 22 and an outlet pipe 23. Here, the inlet pipe 22 is a waste abrasive (S2) is recycled through the recycling unit 30 to be described later is introduced, the discharge pipe 23 is discharged to the abrasive (S1) to be supplied to the polishing unit 10 side. do. In addition, a supply pump 24 for discharging the abrasive S1 contained in the supply cylinder 21 is provided at the discharge port, that is, the discharge pipe 23 side of the supply cylinder 21.

The supply filter 25 is connected to the discharge pipe 23 of the supply cylinder 21, to filter the abrasive (S1) that is pumped and moved through the supply pump 24. That is, the supply filter 25 is to improve the quality of the abrasive (S1) by filtering the size of impurities and particles of the abrasive (S1) before the abrasive (S1) is supplied to the polishing unit 10 side. .

The supply nozzle 26 supplies the abrasive S1 filtered through the supply filter 25 to the polishing unit 10. In this case, the supply nozzle 26 is provided to face the polishing pad 12, and supplies the abrasive S1 to the polishing pad 12. For reference, a supply path 27 through which the filtered abrasive S1 is moved is provided between the supply filter 25 and the supply nozzle 26.

The recycling unit 30 adjusts the concentration and size of the waste abrasive (S2) used in the polishing unit 10 to compensate and supplies it to the supply unit 20 to recycle the waste abrasive (S2). . The recycling unit 30 includes a container 31, an ultrasonic part 36, a filter part 37, a regeneration part 40, and the like.

The collecting container 31 collects the waste abrasive S2 discharged from the polishing unit 10. Here, the collecting container 31 has an inlet 32 connected to the sub discharge pipe 18 and an outlet 33 to be connected to the inlet pipe 22 of the supply container 21. That is, the collecting container 31 collects only the waste abrasive S2 through the sub discharge pipe 18 and then supplies it to the supply unit 20. To this end, a waste abrasive pump 34 for pumping and supplying the waste abrasive S2 to the supply unit 20 is provided at the discharge port 33 side of the container 31.

The ultrasonic unit 36 is installed inside the container 31 to generate ultrasonic waves for releasing the cohesive force of the collected waste abrasive S2. Specifically, the ultrasonic unit 36 is 10 ~ 100KMz, Middle-sonic range of Ultrasonic (Ultrasonic) in accordance with the abrasive grain size and the degree of aggregation of the waste abrasive (S2) collected in the container 31 Ultrasonic waves are generated by varying the frequency range in the range of 100 to 700 KMz and in the mega-sonic range of 700 to 1000 KMz.

The filter unit 37 is provided between the container 31 and the supply unit 20 to filter the waste abrasive S2. The filter unit 37 includes first and second filter members 38 and 39 arranged in parallel to simultaneously filter the waste abrasive S2 pumped through the waste abrasive pump 34. . Here, the number of filter members 38 and 39 constituting the filter unit 37 is not limited thereto.

For reference, a valve 35 is provided between the waste abrasive pump 34 and the filter portion 37 to control the supply and flow rate of the waste abrasive S2 to be supplied to the filter portion 37. The valve 35 selectively blocks the movement of the waste abrasive S2, thereby facilitating replacement of the filter portion 37 that should be replaced periodically during the operation of the polishing apparatus 1.

The regeneration unit 40 regenerates the waste abrasive S2 before the filtered waste abrasive S2 flows into the supply unit 20 for recycling the waste abrasive S2. The regeneration unit 40 includes a large particle measuring unit 41, a concentration measuring unit 42, and a compensating unit 43.

The large particle measuring unit 41 measures the size of the waste abrasive S2, and the concentration measuring unit 42 measures the concentration of the waste abrasive S2. The large particle measuring device 41 and the concentration measuring device 42 are installed near the inlet pipe 22 of the supply container 21.

The compensator 43 compensates for the size and concentration of the waste abrasive based on the information measured by the large particle meter 41 and the concentration meter 42. To this end, the size and concentration information of the waste abrasive S2 measured from the large particle measuring unit 41 and the concentration measuring unit 42 is transmitted to a control unit (not shown), and the compensation unit 43 should compensate for the waste. The size and concentration of the abrasive S2 is determined. That is, the control means (not shown) to determine whether the state of the waste abrasive (S2) flowing into the supply cylinder 21 based on the information of the large particle measuring device 41 and the concentration measuring device 42 is less than the reference value. By doing so, the supply unit 20 to compensate for the failure to meet the reference of the abrasive (S2).

In this case, the compensator 43 supplies an abrasive in which the stock solution and / or pure water of the abrasive S1 is mixed when the state of the waste abrasive S2 is different from the reference value compared to the initial abrasive S1. Supply to the cylinder 21 side. Therefore, the compensator 43 compensates the state of the waste polishing agent S2 to the state of the initial abrasive S1 so that it is re-supplied to the polishing unit 10.

The operation of the polishing apparatus 1 of the wafer W according to the present invention having the above configuration will be described in detail with reference to FIG. 2.

First, the abrasive S1 contained in the supply unit 20 is pumped by the supply pump 24 and filtered through the supply filter 25, and then the polishing unit 10 through the supply nozzle 26. Sprayed into. Then, the polishing unit 10 polishes the surface of the wafer W by a mechanical friction between the wafer W and the polishing pad 12 and a chemical reaction by the polishing agent S1. After the polishing process of the wafer W, the waste abrasive S2 remaining on the wafer W and the polishing pad 12 is cleaned through pure water supplied from the pure water supply unit 14.

Meanwhile, during the polishing process of the wafer W, the waste abrasive S2 discharged from the surface plate 11 flows into the main discharge pipe 17 through the receiving member 15. The waste abrasive (S2) thus introduced is introduced into the sub discharge pipe (18) by the opening of the control valve (19), and then flows back into the container (31) of the recycling unit (30).

The waste abrasive S2 collected in the collecting container 31 is released by the ultrasonic waves generated from the ultrasonic unit 36, and then the cohesive force is released, and is pumped by the waste abrasive pump 34 to move to the filter unit 37. At this time, the valve 35 is in a state in which the movement of the waste abrasive S2 to the filter portion 37 is opened.

The waste abrasive S2 filtered through the filter unit 37 is introduced into the supply container 21 after the presence and the concentration of the large particles are measured through the large particle measuring unit 41 and the concentration measuring unit 42. . When the state information of the waste abrasive S2 measured in this way is different from the reference value compared with the state of the initial abrasive S1, the compensator 43 is supplied to the supply cylinder 21 with the stock solution of the new abrasive S1. The mixed liquid in which the abrasive S1 and pure water are mixed is supplied to the supply cylinder 21 to compensate for the state of the abrasive S1 as a reference value. Therefore, the waste abrasive S2 is supplied to the polishing unit 10 in the same state as the initial abrasive S1, and can be used again for polishing the wafer W.

On the other hand, the pure water supplied from the pure water supply unit 14 is discharged to the outside through the main discharge pipe 17 through the receiving member 15 after cleaning the wafer (W) and the polishing pad 12. At this time, the supply of pure water to the sub discharge pipe 18 is blocked by the control valve 19 between the main discharge pipe 17 and the sub discharge pipe 18. Therefore, the pure water can be discharged together with the waste abrasive S2 remaining in the main discharge pipe 17 via the main discharge pipe 17.

As described above, although described with reference to the preferred embodiment of the present invention, those skilled in the art various modifications and variations of the present invention without departing from the spirit and scope of the invention described in the claims below I can understand that you can.

1 is a schematic configuration diagram for explaining a recycling process of waste abrasive in a conventional wafer polishing apparatus, and

2 is a view schematically showing a wafer polishing apparatus according to the present invention.

<Description of the symbols for the main parts of the drawings>

1: wafer polishing apparatus 10: polishing unit

11: surface plate 12: polishing pad

13: polishing head 16: discharge section

20: supply unit 21: supply container

25: supply filter 26: supply nozzle

30: recycling unit 31: container

36: ultrasonic portion 37: filter portion

40: playback unit 41: large particle measuring instrument

42: concentration meter 43: compensation unit

Claims (18)

A polishing unit for polishing the wafer with an abrasive; A supply unit for supplying the abrasive to the polishing unit; And A recycling unit for supplying the supply unit to the supply unit after compensating the concentration and size of the waste abrasive used in the polishing unit to an initial state; Polishing apparatus for a wafer comprising a. The method of claim 1, The recycling unit, A bin in which the waste abrasive is collected; An ultrasonic unit installed in the container to generate ultrasonic waves for releasing the cohesive force of the collected waste abrasive; A filter unit provided between the container and the supply unit to filter the waste abrasive; And A regeneration unit for regenerating the waste abrasive before the filtered waste abrasive flows into the supply unit; Wafer polishing apparatus comprising a. The method of claim 2, The filter unit, Wafer polishing apparatus comprising a plurality of filter members for filtering the waste abrasive discharged from the container at the same time. The method of claim 2, Wafer polishing apparatus, characterized in that the waste abrasive pump for supplying the waste abrasive to the supply unit at the discharge port side of the container. The method of claim 2, The regeneration unit, A large particle measuring instrument for measuring the size of the waste abrasive; A concentration meter for measuring the concentration of the waste abrasive; And A compensator for compensating for the size and concentration of the waste abrasive based on the information measured from the large particle and concentration meter; Wafer polishing apparatus comprising a. The method of claim 5, And the compensating unit supplies an abrasive in which the stock solution and / or pure water of the abrasive is mixed to the supply unit. The method of claim 5, The supply unit, A supply container in which the abrasive to be supplied is accommodated; A feed filter provided at an outlet side of the feed container to filter the abrasive; And A supply nozzle for supplying the filtered abrasive to the polishing unit; Wafer polishing apparatus comprising a. The method of claim 7, wherein Wafer polishing apparatus, characterized in that the supply pump for supplying the abrasive to the supply filter side at the outlet side of the supply cylinder. 8. The method according to any one of claims 1 to 7, The polishing unit, A surface plate with a polishing pad; A polishing head for pressing the wafer against the polishing pad; A pure water supply unit supplying pure water for cleaning the polishing pad and the wafer after the polishing process of the wafer; A receiving member for collecting waste abrasive and pure water used during the polishing and cleaning process of the wafer; And A discharge part for discharging the waste abrasive and the pure water collected in the receiving member; Wafer polishing apparatus comprising a. The method of claim 9, The discharge portion, A main discharge pipe connected to the receiving member; A sub discharge pipe connecting the main discharge pipe and the recycling unit to each other; And A control valve for moving only the waste abrasive to the sub discharge pipe side between the main and sub discharge pipes; Wafer polishing apparatus comprising a. A polishing unit for polishing the wafer with an abrasive to clean the wafer with a cleaner; A supply unit for supplying the abrasive to the polishing unit; And A recycling unit for recycling the waste abrasive used in the polishing unit by releasing the cohesive force of the waste abrasive and measuring the concentration and size to compensate for the state before the polishing process and then moving to the supply unit; Including; After the waste abrasive and the cleaning agent discharged from the polishing unit is discharged through one discharge pipe, only the waste abrasive is moved to the recycling unit side. The method of claim 11, And a control valve provided at the inlet side of the recycling unit to move only the waste abrasive to the recycling unit among the waste abrasive and the cleaning agent discharged from the polishing unit. The method of claim 12, The recycling unit, A waste container in which waste abrasive flowing through the sub discharge pipe is collected; An ultrasonic unit installed in the container to generate ultrasonic waves for releasing the cohesive force of the collected waste abrasive; At least one filter provided between the container and the supply unit to filter the waste abrasive; And A regeneration unit for regenerating the waste abrasive before the filtered waste abrasive flows into the supply unit; Wafer polishing apparatus comprising a. The method of claim 13, Wafer polishing apparatus, characterized in that the waste abrasive pump for supplying the waste abrasive to the supply unit at the discharge port side of the container. The method of claim 13, The regeneration unit, A large particle measuring instrument for measuring the size of the waste abrasive; A concentration meter for measuring the concentration of the waste abrasive; And A compensator for compensating for the size and concentration of the waste abrasive based on the information measured from the large particle and concentration meter; Wafer polishing apparatus comprising a. The method of claim 15, And the compensating unit supplies an abrasive in which the stock solution and / or pure water of the abrasive is mixed to the supply unit. The method of claim 15, The supply unit, A supply container in which the abrasive to be supplied is accommodated; A feed filter provided at an outlet side of the feed container to filter the abrasive; And A supply nozzle for supplying the filtered abrasive to the polishing unit; Wafer polishing apparatus comprising a. The method of claim 17, Wafer polishing apparatus, characterized in that the supply pump for supplying the abrasive to the supply filter side at the outlet side of the supply cylinder.

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