WO2008001969A1

WO2008001969A1 - Loading unit of chemical mechanical polishing apparatus and method of detecting proper position of wafer using the same

Info

Publication number: WO2008001969A1
Application number: PCT/KR2006/002894
Authority: WO
Inventors: Young Su Heo
Original assignee: Doosan Mecatec Co., Ltd.
Priority date: 2006-06-29
Filing date: 2006-07-21
Publication date: 2008-01-03
Also published as: KR100744036B1; TW200802682A

Abstract

A loading unit of a chemical mechanical polishing apparatus and a method of detecting a proper position of a wafer using the same are provided. The loading unit, for loading a wafer to be chemically mechanically polished or a chemically mechanically polished wafer onto a loading plate, includes: an ejection part for ejecting a cleaning fluid supplied through a cleaning fluid supply line onto the bottom of the wafer supported on the loading plate at a plurality of locations around the wafer's circumference; a measurement part for measuring whether the cleaning fluid is normally ejected from the ejection part; and a controller for comparing a measurement value measured by the measurement part with a predetermined value to determine whether the wafer is loaded in a proper position. Therefore, it is possible to stably load and unload the wafer onto/from the chemical mechanical polishing apparatus by detecting whether the wafer is loaded in the proper position on the loading plate.

Description

LOADING UNIT OF CHEMICAL MECHANICAL POLISHING

APPARATUS AND METHOD OF DETECTING PROPER

POSITION OF WAFER USING THE SAME

Technical Field

[1] The present invention relates to a loading unit of a chemical mechanical polishing apparatus and a method of detecting a proper position of a wafer using the same, and more particularly, to a loading unit of a chemical mechanical polishing apparatus and a method of detecting a proper position of a wafer using the same, capable of detecting whether a wafer is loaded in a proper position on a loading plate of the chemical mechanical polishing apparatus. Background Art

[2] Generally, semiconductor devices are manufactured through various processes such as a deposition process, a photolithography process, an etching process, an ion implantation process, and so on, which are performed on a silicon wafer.

[3] Specifically, various process layers may be formed on the silicon wafer during the manufacturing processes. The process layers may be partially and selectively removed or patterned, additional layers may be deposited on previously formed layers, and processes may be repeated as necessary.

[4] The process layers may be, for example, an insulating layer, a gate oxide layer, a conductive layer, a metal or glass layer, and so on.

[5] Therefore, in some processes, the top surface of a process layer formed on a wafer may be planarized in preparation for depositing a following process layer.

[6] That is, the silicon wafer is polished to planarize the top process layer in order to stably perform the following process.

[7] In this process, the wafer polishing process is a process of planarizing a wafer surface, for example, a chemical mechanical polishing/planarization (CMP) method of planarizing a wafer surface by applying a chemical slurry on a polishing pad in frictional contact with the wafer surface, and moving the wafer and the polishing pad relative to one another with the wafer surface being pressed into the polishing pad.

[8] Such a chemical mechanical polishing apparatus as described above is disclosed in

Korean Patent Registration No. 536175, filed by the present applicant.

[9] FlG. 1 is a schematic view of a conventional chemical mechanical polishing apparatus.

[10] Referring to FlG. 1, the conventional chemical mechanical polishing apparatus may include a platen 10 for mounting a polishing pad 11 in contact with a wafer surface to polish the wafer surface by friction, a polishing head 20 for fixedly chucking the wafer to press the wafer onto the polishing pad 11 to create friction, a spindle 30 for rotating the polishing head 20 on which the wafer is mounted while it is pressed against the polishing pad 11, and a loading unit 40 for loading a wafer to be polished onto the polishing head 20 and unloading the polished wafer from the polishing head 20.

[11] The loading unit 40 includes a loading cup 41, a loading plate 42 formed on an uppermost part of the loading cup 41 to support a wafer on its upper surface, an arm 44 connected to the loading cup 41 to allow the loading plate 42 and the polishing head 20 to mount/dismount the wafer, and a rotary shaft 43 for pivoting and raising/lowering the loading cup 41 toward the polishing head 20.

[12] As described above, the loading unit 40 repeatedly performs wafer loading and unloading operations, especially, in connection with the polishing head 20 or a robot arm (not shown).

[13] In addition, the wafer loaded on the loading plate 42 of the loading unit 40 should be positioned in a proper position on the loading plate 42 so that the wafer is stably transferred to the polishing head 20 and the robot arm.

[14] Meanwhile, the conventional chemical mechanical polishing apparatus further includes a photo-sensor (not shown) having a light emitting part and a light receiving part installed at the loading unit 40 to detect whether the wafer is loaded onto the loading plate 42.

[15] However, the loading unit 40 of the conventional chemical mechanical polishing apparatus can only detect whether the wafer is loaded onto the loading plate 42, not whether it is loaded in a proper position.

[16] As a result, when the wafer is not loaded in the proper position on the loading plate

42, since the wafer cannot be properly gripped by the polishing head 20 or the robot arm, the wafer may be incorrectly transferred to a following apparatus or damaged during the process. Disclosure of Invention Technical Problem

[17] In order to solve the foregoing and/or other problems, it is an aspect of the present invention to provide a loading unit of a chemical mechanical polishing apparatus and a method of detecting a proper position of a wafer using the same capable of detecting whether a wafer is loaded in a proper position on a loading plate. Technical Solution

[ 18] One aspect of the present invention provides a loading unit of a chemical mechanical polishing apparatus for loading a wafer to be chemically mechanically polished, or a chemically mechanically polished wafer, onto a loading plate, the loading unit including: an ejection part for ejecting a cleaning fluid supplied through a cleaning fluid supply line onto the bottom of the wafer supported on the loading plate at a plurality of locations around the wafer's circumference; a measurement part for measuring whether the cleaning fluid is normally ejected from the ejection part; and a controller for comparing the measurement value measured by the measurement part with a predetermined value to determine whether the wafer is loaded in a proper position.

[19] The measurement part may measure a pressure or a flow rate of the cleaning fluid ejected from the ejection part.

[20] The ejection part may eject the cleaning fluid onto three equally spaced-apart positions around the circumference of the wafer loaded in the proper position on the loading plate.

[21] The controller may further include an alarm generating part for stopping operation of the apparatus or generating an alarm to alert a user when it is determined that the wafer is improperly loaded on the loading plate.

[22] Another aspect of the present invention provides a method of detecting a proper position of a wafer using a loading unit of a chemical mechanical polishing apparatus including: (a) loading a wafer to be chemically mechanically polished, or a chemically mechanically polished wafer, onto a loading plate; (b) ejecting a cleaning fluid onto the bottom of the wafer loaded on the loading plate at a plurality of locations around the wafer's circumference; (c) measuring whether the cleaning fluid is normally ejected onto the bottom of the wafer in step (b); and (d) comparing a value measured in step (c) with a predetermined value to determine whether the wafer is loaded in the proper position.

[23] Step (c) may involve measuring a pressure or a flow rate of the cleaning fluid.

[24] The method may further include stopping operation of the apparatus or generating an alarm to alert a user when it is determined that the wafer is improperly loaded on the loading plate. Advantageous Effects

[25] It is possible to stably load and unload a wafer onto/from a chemical mechanical polishing apparatus by detecting whether the wafer is loaded in a proper position on a loading plate of a loading cup.

[26] In addition, since the proper position of the wafer on the loading plate is detected using an ejection part for cleaning the wafer with fluid, the apparatus can have a simple structure and still readily detect whether the wafer is loaded in a proper position. Brief Description of the Drawings

[27] These and/or other aspects and advantages of the present invention will become apparent and more readily appreciated from the following description of exemplary embodiments of the invention, taken in conjunction with the accompanying drawings of which:

[28] FlG. 1 is a schematic view of a conventional chemical mechanical polishing apparatus;

[29] FlG. 2 is a plan view of a loading unit of a chemical mechanical polishing apparatus in accordance with an exemplary embodiment of the present invention;

[30] FlG. 3 is a block diagram of a loading unit of a chemical mechanical polishing apparatus in accordance with an exemplary embodiment of the present invention; and

[31] FlG. 4 is a flowchart showing a method of detecting a proper position of a wafer using a loading unit of a chemical mechanical polishing apparatus in accordance with an exemplary embodiment of the present invention. Best Mode for Carrying Out the Invention

[32] Exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings, throughout which like reference numerals refer to like elements.

[33] FlG. 2 is a plan view of a loading unit of a chemical mechanical polishing apparatus in accordance with an exemplary embodiment of the present invention, and FlG. 3 is a block diagram of a loading unit of a chemical mechanical polishing apparatus in accordance with an exemplary embodiment of the present invention.

[34] Referring to FIGS. 2 and 3, a loading unit of a chemical mechanical polishing apparatus in accordance with an exemplary embodiment of the present invention includes a loading cup 100 for loading a wafer to be chemically mechanically polished, or a chemically mechanically polished wafer, onto a loading plate 110, an ejection part 200 for ejecting a cleaning fluid supplied through a cleaning fluid supply line 900 onto the bottom of the wafer supported on the loading plate at a plurality of locations around the wafer's circumference 110, a measurement part 300 for measuring an ejection pressure or a flow rate of the cleaning fluid to detect whether the cleaning fluid is normally ejected from the ejection part 200, and a controller 400 for comparing the measurement value measured by the measurement part with a predetermined value to determine whether the wafer is loaded in a proper position.

[35] The loading plate 110 is installed at an uppermost part of the loading cup 100 so that the wafer to be polished or the polished wafer is loaded on its upper surface.

[36] In addition, the loading plate 110 has a groove 111 conforming to the circumference of the wafer to stably support the wafer, and a plurality of projections 112 formed outside the groove 111 to mount/dismount the wafer to/from a polishing head (not shown) or a robot arm (not shown). [37] The wafer loaded by the loading plate 110 is mounted on the polishing head to be polished or transferred to a following process by the robot arm and so on.

[38] Further, the cleaning fluid, such as deionized water, is supplied onto the loading plate of the loading unit in accordance with an exemplary embodiment of the present invention.

[39] That is, since the loading unit of the chemical mechanical polishing apparatus in accordance with an exemplary embodiment of the present invention may be contaminated by the matter removed during polishing or chemical slurry remaining on the polishing head or the wafer transferred from the polishing head, the cleaning fluid is supplied to clean the loading cup 100, the loading plate 110, the polishing head, and the wafer transferred from the polishing head. In addition, the cleaning fluid may be supplied to wet the wafer loaded on the loading plate 110 before polishing.

[40] Specifically, the ejection part 200 having a plurality of ejection ports for ejecting the cleaning fluid supplied through the cleaning fluid supply line 900 onto a plurality of locations around the perimeter of the bottom of the wafer is installed at the loading plate 110.

[41] While the ejection part 200 is shown to pass through the loading plate 110 to be in communication with the cleaning fluid supply line 900, the ejection part 200 may be an ejection nozzle (not shown) installed in the loading cup 100 for ejecting the cleaning fluid toward the loading plate 110.

[42] That is, the ejection part 200 is formed to pass through the loading plate 110 to eject the cleaning fluid onto the plurality of parts along the lower periphery of the wafer supported on the loading plate 110, to enable determination of whether the wafer is loaded in a proper position on the loading plate 110.

[43] Therefore, in this exemplary embodiment, when the wafer is unstably loaded in an improper position on the loading plate 110, measurement of physical parameters generated from the ejection part 200 yields different results than when the wafer is loaded in the proper position on the loading plate 110, thereby enabling determination of whether the wafer is loaded in the proper position.

[44] For this purpose, the ejection part 200 may have three ejection ports formed on the loading plate 110 equally spaced apart around the circumference of the wafer loaded in the proper position on the loading plate 110, such that it is accurately determined whether the wafer is loaded in the proper position using a minimum number of ejection ports.

[45] That is, as shown in FIG. 2, the ejection ports are formed at the loading plate 110 spaced apart by angles of 120 with respect to the center of the loading plate 110.

[46] Meanwhile, the cleaning fluid supply line 900 includes a valve 910 for controlling the cleaning fluid supplied from a cleaning fluid supply source (not shown), a regulator 920 for regulating a pressure of the cleaning fluid, and a flow meter 930 for adjusting a flow rate of the cleaning fluid passing through the regulator 920.

[47] Therefore, the cleaning fluid to be supplied to the ejection part 200 through the cleaning fluid supply line 900 is regulated by the regulator 920 to have a predetermined pressure, and adjusted by the flow meter 930 to have a predetermined flow rate.

[48] Then, the cleaning fluid having the pressure and the flow rate regulated by the regulator 920 and the flow meter 930 is ejected onto the bottom of the wafer around its circumference through the ejection part 200 formed at the loading plate 110.

[49] In addition, the cleaning fluid supply line 900 includes a measurement part 300 for measuring a pressure of the cleaning fluid before it is supplied to the ejection ports, to determine whether the cleaning fluid is normally ejected through the ejection part 200.

[50] The measurement part 300 may measure a pressure of the cleaning fluid ejected from the ejection part 200 using a pressure switch (not shown) to determine whether the cleaning fluid is normally ejected, or measure a flow rate of the cleaning fluid ejected from the ejection part 200 using a flow meter (not shown) to determine whether the cleaning fluid is normally ejected.

[51] In the present exemplary embodiment, measuring the pressure of the cleaning fluid ejected from the ejection part 200 to determine whether the cleaning fluid is normally ejected will be described.

[52] In addition, the measurement part 300 may be configured to measure the pressure of the cleaning fluid on the cleaning fluid supply line 900 in the front of the ejection part 200, or measure the pressure of the cleaning fluid in the front of each of the ejection ports.

[53] When the wafer is improperly loaded on the loading plate 110, since the ejection part 200 is closely adhered to the bottom of the wafer not to allow the cleaning fluid to be ejected, the measurement part 300 measures the pressure drop at the ejection part 200.

[54] Then, the controller 400 compares the measurement value of the measurement part

300 and a predetermined value. As a result of the comparison, when the difference between the values is larger than an error tolerance, it is determined that the wafer is improperly loaded.

[55] The controller 400 may further include an alarm generator 500 for stopping operation of the apparatus or generating an alarm to alert a user of improper loading of the wafer on the loading plate 110.

[56] The alarm generator 500 may be connected to a main controller (not shown) of the apparatus to transmit a signal for stopping operation of the entire apparatus when the controller 400 determines that the water is improperly loaded, or may be configured to output an audible or visible alarm.

[57] Hereinafter, a method of detecting a proper position of a wafer using a loading unit of a chemical mechanical polishing apparatus in accordance with an exemplary embodiment of the present invention will be described.

[58] FlG. 4 is a flowchart showing a method of detecting a proper position of a wafer using a loading unit of a chemical mechanical polishing apparatus in accordance with an exemplary embodiment of the present invention.

[59] Referring to FlG. 4 together with FIGS. 2 and 3, a method of detecting a proper position of a wafer using a loading unit of a chemical mechanical polishing apparatus in accordance with an exemplary embodiment of the present invention includes (a) loading a wafer to be chemically mechanically polished, or a chemically mechanically polished wafer, onto the loading plate 110 (SlOl), (b) ejecting the cleaning fluid onto the bottom of the wafer loaded on the loading plate 110 at a plurality of locations around its perimeter (S 102), (c) measuring whether the cleaning fluid is ejected onto the wafer normally (S 103), and (d) comparing a value measured in step S 103 with a predetermined value to determine whether the wafer is loaded in the proper position (S 104).

[60] First, as described in step SlOl, the wafer to be chemically mechanically polished or the chemically mechanically polished wafer is loaded onto the loading plate 110 of the loading cup 100.

[61] The loading plate 110 of the loading cup 100 may receive the wafer from a polishing head or a robot arm.

[62] Next, in step S 102, the cleaning fluid is ejected in order to clean the loading plate

110, the loading cup 100, the polishing head, the wafer, and so on, as well as to determine whether the wafer is improperly loaded on the loading plate 110.

[63] Then, in step S 103, the measurement part 300 measures the pressure or the flow rate of the cleaning fluid ejected from the ejection part 200.

[64] For example, when the wafer is improperly loaded on the loading plate 110, since the cleaning fluid is ejected without any load, like being ejected out into the open air, the pressure of the cleaning fluid may drop, and the flow rate of the cleaning fluid may increase.

[65] According to experiments performed by the applicant, when the cleaning fluid is ejected from the ejection part 200 when the wafer is loaded in a proper position on the loading plate 110, a measured flow rate is about 0.371/min. On the other hand, when the cleaning fluid is ejected from the ejection part 200 when the wafer is improperly loaded, a measured flow rate is about 0.611/min, which is significantly higher.

[66] According to experiments performed by the applicant, when the cleaning fluid is ejected from the ejection part 200 when the wafer is loaded in a proper position on the loading plate 110, a measured pressure is about 6.7psi. On the other hand, when the cleaning fluid is ejected from the ejection part 200 when the wafer is improperly loaded, a measured pressure is about 2.2psi, which is significantly lower.

[67] Next, in step S 104, a controller 400 compares the pressure or the flow rate of the cleaning fluid at the ejection part 200 measured by the measurement part 300 with a predetermined pressure or a predetermined flow rate to determine whether the wafer is loaded in a proper position.

[68] In step S 104, as described in the experiments, when the difference between the pressure or the flow rate and the predetermined pressure or the predetermined flow rate is larger than an error tolerance, the controller 400 determines that the wafer is improperly loaded.

[69] In step S 104, the controller 400 may further perform a step S 105 of stopping operation of the apparatus or generating an alarm to alert a user of improper loading of the wafer when the wafer is improperly loaded on the loading plate 110.

[70] While exemplary embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes may be made to these exemplary embodiments without departing from the spirit and scope of the invention as defined by the appended claims and their equivalents. Industrial Applicability

[71] As can be seen from the foregoing, in accordance with the present invention, it is possible to stably load and unload a wafer onto/from a chemical mechanical polishing apparatus by detecting whether the wafer is loaded in a proper position on a loading plate of a loading cup.

[72] In addition, since the proper position of the wafer on the loading plate is detected using an ejection part for cleaning the wafer with fluid, the apparatus can have a simple structure and still readily detect whether the wafer is loaded in a proper position.

Claims

[1] A loading unit of a chemical mechanical polishing apparatus for loading a wafer to be chemically mechanically polished, or a chemically mechanically polished wafer, onto a loading plate, the loading unit comprising: an ejection part for ejecting a cleaning fluid supplied through a cleaning fluid supply line onto the bottom of the wafer supported on the loading plate at a plurality of locations around the wafer's circumference; a measurement part for measuring whether the cleaning fluid is normally ejected from the ejection part; and a controller for comparing a measurement value measured by the measurement part with a predetermined value to determine whether the wafer is loaded in a proper position.

[2] The loading unit of a chemical mechanical polishing apparatus according to claim 1, wherein the measurement part measures a pressure or a flow rate of the cleaning fluid ejected from the ejection part.

[3] The loading unit of a chemical mechanical polishing apparatus according to claim 2, wherein the ejection part ejects the cleaning fluid onto three equally spaced-apart positions around the circumference of the wafer loaded in the proper position on the loading plate.

[4] The loading unit of a chemical mechanical polishing apparatus according to claim 2, wherein the controller further comprises an alarm generating part for stopping operation of the apparatus or generating an alarm to alert a user when it is determined that the wafer is improperly loaded on the loading plate.

[5] The loading unit of a chemical mechanical polishing apparatus according to claim 1, wherein the ejection part ejects the cleaning fluid onto three equally spaced-apart positions around the circumference of the wafer loaded in the proper position on the loading plate.

[6] The loading unit of a chemical mechanical polishing apparatus according to claim 1, wherein the controller further comprises an alarm generating part for stopping operation of the apparatus or generating an alarm to alert a user when it is determined that the wafer is improperly loaded on the loading plate.

[7] A method of detecting a proper position of a wafer using a loading unit of a chemical mechanical polishing apparatus according to claim 1, the method comprising:

(a) loading a wafer to be chemically mechanically polished, or a chemically mechanically polished wafer, onto a loading plate;

(b) ejecting a cleaning fluid onto the bottom of the wafer loaded on the loading plate at a plurality of locations around the wafer's circumference;

(c) measuring whether the cleaning fluid is normally ejected onto the bottom of the wafer in step (b); and

(d) comparing a value measured in step (c) with a predetermined value to determine whether the wafer is loaded in the proper position.

[8] The method according to 7, wherein step (c) measures a pressure or a flow rate of the cleaning fluid.

[9] The method according to 8, wherein step (d) further comprises stopping operation of the apparatus or generating an alarm to alert a user when it is determined that the wafer is improperly loaded on the loading plate.

[10] The method according to claim 7, wherein step (d) further comprises stopping operation of the apparatus or generating an alarm to alert a user when it is determined that the wafer is improperly loaded on the loading plate.