WO2008117903A1

WO2008117903A1 - Apparatus for inspecting wafer and method therefor

Info

Publication number: WO2008117903A1
Application number: PCT/KR2007/002068
Authority: WO
Inventors: Gun Hwan Kim; Eun Whan Kim
Original assignee: Gun Hwan Kim; Eun Whan Kim
Priority date: 2007-03-26
Filing date: 2007-04-27
Publication date: 2008-10-02
Also published as: KR100759293B1

Abstract

Provided is a wafer inspection apparatus capable of reducing a time consumed for inspecting a wafer. The wafer inspection apparatus includes a cassette mounting part for fixing a cassette in which a wafer is accommodated, a macro inspection part for visually inspecting front and rear surfaces of the wafer illuminated by an illumination device, a micro inspection part for accurately inspecting defects of the wafer using a microscope, and a six- axis robot for unloading the wafer from the cassette disposed at the cassette mounting part or loading the cassette thereinto, and moving and rotating the wafer in a gripped state depending on inspection conditions required by the macro inspection part or the micro inspection part. The six-axis robot has six degrees of freedom to freely rotate and move. Therefore, it is possible to directly load and unload the wafer using the six-axis robot, remarkably reduce a tack time by performing macro inspection, micro inspection and side inspection of the wafer, and increase cost competitiveness.

Description

APPARATUS FOR INSPECTING WAFER AND METHOD

THEREFOR

Technical Field

[1] The present invention relates to an apparatus for inspecting a wafer and a method for inspecting a wafer using the same, and more particularly, to an apparatus for inspecting a wafer and a method for inspecting a wafer using the same capable of reducing a time consumed for wafer inspection. Background Art

[2] In general, a wafer inspection apparatus is an apparatus for inspecting whether a defect exists in a wafer, after manufacturing the wafer, which performs macro inspection using an inspector's eyes, and micro inspection using equipment such as a microscope. In order to convey the wafer during the macro inspection and the micro inspection, a robot is used.

[3] FIG. 1 is a plan view of a conventional wafer inspection apparatus, FIGS. 2 to 4 are views showing a wafer inspection process performed in the conventional wafer inspection apparatus.

[4] As shown in FIGS. 1 to 4, the conventional wafer inspection apparatus 100 includes a wafer support arm 160 for supporting and sucking a wafer 120 to perform micro inspection and macro inspection, a macro stage 180 (or a micro stage 145) disposed at about a center of the wafer support arm 160 to suck the wafer 120 to perform the micro inspection and the macro inspection, a wafer support frame 190 for inverting the wafer, a microscope 130 for performing the micro inspection, a robot 155 for seating the wafer 120 on a robot arm 170 and moving the wafer 120 to perform the micro inspection and the macro inspection, and a cassette 110 for accommodating the wafer 120.

[5] Hereinafter, the wafer inspection process performed in the wafer inspection apparatus will be described.

[6] First, as shown in FIGS. 1 and 2, the wafer 120 accommodated in the cassette 110 is disposed on the robot arm 170 of the robot and then unloaded onto a conveyance part 135. Next, the unloaded wafer 121 is located on the wafer support arm 160 of the wafer inspection apparatus, and then, vacuum sucked by air suction ports 161 formed at the wafer support arm 160. That is, the wafer 121 is located on the wafer support arm 160 in a sucked state.

[7] Then, as shown in FIGS. 1 and 3, the wafer support arm 160 moves to the macro stage 180 for performing macro inspection to perform the macro inspection of the wafer 122 located on the moved wafer support arm 160. Upon the macro inspection, vacuum suction of the vacuum suction ports 161 of the wafer support arm 160 is released from the wafer 122, and vacuum suction ports 181 of the macro stage 180 vacuum suck a wafer.

[8] In order to inspect a rear surface of the wafer 122, the air suction ports 161 and 181 of the wafer support arm 160 and/or the macro stage 180 release the vacuum state of the vacuum sucked wafer 122, and air suction ports 191 of a wafer rotation frame 190 vacuum suck the wafer 122. Then, the wafer 122 is inverted by the wafer rotation frame 190 to 180°. Therefore, the macro inspection to the rear surface of the 180° inverted wafer 122 is performed.

[9] Next, as shown in FIGS. 1 and 4, the wafer rotation frame 190 is rotated again to

180° to recover the wafer 122 to its original position such that the wafer 122 is moved to the micro stage 145 to perform the micro inspection, and then, the wafer 122 is vacuum sucked by the air suction ports of the micro stage 145, similar to the macro stage 180. Continuously, the moved wafer 123 is located under an object lens (not shown) of the microscope 130 to allow an operator to perform the micro inspection through the microscope 130.

[10] At this time, the operator uses functions of a joystick, a four- way button, a track ball, and so on, installed in the microscope, to rotate the wafer in all directions to perform the micro inspection. In addition, in order to inspect side defects of the wafer, the wafer 124 is moved to a side inspection position (not shown) such that edge (side) parts of the wafer are inspected.

[11] Then, as shown in FIG. 1, the wafer 124, in which the micro inspection or the side inspection is completed, is moved to the micro stage 145 and the conveyance part 135, and finally, loaded into the cassette by the robot arm of the robot to be accommodated therein.

[12] As described above, since the conventional wafer inspection apparatus moves the wafer to numerous stages in order to perform the micro inspection, the macro inspection, and the side inspection, thereby causing ineffective tack time, complicating structure and units of equipment due to the numerous stages, reducing space utilization, and lowering price competitiveness. Disclosure of Invention Technical Problem

[13] In order to solve the foregoing and/or other problems, it is an aspect of the present invention to provide an apparatus for inspecting a wafer capable of effectively performing macro inspection, micro inspection, and side inspection using a six-axis robot to reduce tack time and removing numerous units to improve price compet- itiveness, and a method of inspecting a wafer using the wafer inspection apparatus including the six-axis robot. Technical Solution

[14] The foregoing and/or other aspects of the present invention may be achieved by providing an apparatus for inspecting a wafer including: a cassette mounting part for fixing a cassette in which a wafer is accommodated; a macro inspection part for visually inspecting front and rear surfaces of the wafer illuminated by an illumination device; a micro inspection part for accurately inspecting defects of the wafer using a microscope; and a six-axis robot for unloading the wafer from the cassette disposed at the cassette mounting part or loading the cassette thereinto, and moving and rotating the wafer in a gripped state depending on inspection conditions required by the macro inspection part or the micro inspection part.

[15] Here, the six-axis robot may further include a base part fixed to the wafer inspection apparatus; a rotation drive part rotatably installed on the base part; a first arm, a first end of which is connected to the rotation drive part, pivotable with respect to a shaft perpendicular to its longitudinal shaft within a predetermined angle range; a second arm, a first end of which is connected to a second end of the first arm, pivotable with respect to a shaft perpendicular to the longitudinal shaft of the first arm, and rotatable with respect to its longitudinal shaft; a third arm, a first end of which is connected to a second end of the second arm, pivotable with respect to a shaft perpendicular to the longitudinal shaft of the second arm, and rotatable with respect to its longitudinal shaft; and a wafer holder connected to a second end of the third arm, and seating the wafer.

[16] According to the embodiment, the six-axis robot may be fixed or may be movable in forward, backward, leftward and rightward directions.

[17] In addition, the six-axis robot may further include a wafer rotation unit for rotating the wafer in a gripped state.

[18] Further, the wafer holder may be formed of a transparent material, preferably, formed of any one of transparent engineering plastic, a carbon nano tube material, and glass.

[19] Furthermore, the wafer holder may have a substantially U shape.

[20] Another aspect of the present invention may be achieved by providing a method of inspecting a wafer using a wafer inspection apparatus including a six-axis robot including: unloading a wafer from a cassette; illuminating front and rear surfaces of the wafer disposed at various positions in a state that the wafer is gripped by the six-axis robot and visually inspecting the wafer; accurately inspecting the wafer gripped by the six-axis robot through a microscope; and loading the wafer, in which inspection is completed, into the cassette. [21] According to the embodiment, the method may further include rotating and gripping the wafer in a state that the wafer is vertically stood by the six-axis robot, and then, inspecting side defects of the wafer.

[22] In addition, when the microscope includes a line sensor camera, the method may include inspecting pattern defects of the wafer by passing the wafer under the line sensor camera in a state that the wafer is gripped by the six-axis robot (AOI).

Advantageous Effects

[23] As can be seen from the foregoing, it is possible to directly load/unload a wafer using a six-axis robot, without any stage, and perform macro inspection, micro inspection, and side inspection of the wafer, thereby remarkably reducing tack time.

[24] In addition, since numerous units related to a micro inspection state, a macro inspection stage, an X-, Y- and Z-axes moving stage, wafer side inspection, and so on, can be removed, cost competitiveness can be increased.

[25] Further, removal of the numerous units can remove various causes of equipment errors, and thus, generation of deformation and rear surface defects of the wafer can be prevented.

[26] Furthermore, it is possible to reduce the size of the equipment to increase space utilization of a clean room (C/R) using the six-axis robot. Brief Description of the Drawings

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

[28] FIG. 1 is a plan view of a conventional wafer inspection apparatus;

[29] FIGS. 2 to 4 are views showing a wafer inspection process performed in the conventional wafer inspection apparatus;

[30] FIG. 5 is a plan view of an apparatus for inspecting a wafer in accordance with an exemplary embodiment of the present invention;

[31] FIGS. 6 and 7 are views showing structure of a six-axis robot used in the wafer inspection apparatus in accordance with an exemplary embodiment of the present invention;

[32] FIGS. 8 and 9 are views showing a macro inspection process of inspecting defects of a wafer using the wafer inspection apparatus in accordance with an exemplary embodiment of the present invention, wherein FIG. 8 is a plan view of the wafer inspection apparatus upon macro inspection, and FIG. 9 is a left side view of the wafer inspection apparatus upon macro inspection;

[33] FIGS. 10 to 12 are views showing a micro inspection process of inspecting defects of a wafer using the wafer inspection apparatus in accordance with an exemplary embodiment of the present invention, wherein FIG. 10 is a front view of the wafer inspection apparatus upon micro inspection, FIG. 11 is a plan view of the wafer inspection apparatus upon micro inspection, and FIG. 12 is a right side view of the wafer inspection apparatus;

[34] FIG. 13 is a front view showing a side inspection process of inspecting side defects of a wafer using the wafer inspection apparatus in accordance with an exemplary embodiment of the present invention; and

[35] FIG. 14 is a front view showing an AOI process of inspecting pattern defects of a wafer using the wafer inspection apparatus and the six-axis robot in accordance with an exemplary embodiment of the present invention. Mode for the Invention

[36] Reference will now be made in detail to the embodiments of the present invention, examples of which are illustrated in the accompanying drawings. In the following description and related drawings, like reference numerals designates like elements.

[37] FIG. 5 is a plan view of an apparatus for inspecting a wafer in accordance with an exemplary embodiment of the present invention.

[38] Referring to FIG. 5, a wafer inspection apparatus 200 in accordance with an exemplary embodiment of the present invention includes a cassette mounting part (not shown), a macro inspection part 250, a micro inspection part 280, a six-axis robot 270, and a microscope 230.

[39] The cassette mounting part (not shown) fixes a cassette 210, in which a wafer 220 is accommodated. The cassette 210 can be moved, and a plurality of wafers 220 to be inspected or inspected wafers 230 can be accommodated in the cassette 210.

[40] The macro inspection part 250 is a unit for inspecting front and rear surfaces of a wafer 221 illuminated by a macro inspection illumination device 251 through an operator's eyes 240 such that defects such as cracks, spots, and so on, existing on the front and rear surfaces of the wafer 221 can be detected by the operator's eyes 240.

[41] The microscope 230 is used in a micro inspection part 280 or a side inspection part

290 to magnify the wafer 222 to perform accurate inspection. The microscope 230 includes an object lens 231, a focus adjustment shaft (not shown), and an eye lens 235.

[42] The object lens 231 can adjust its magnification to accurately inspect whether defects exist in wafers 222 and 223. While a focus adjustment shaft (not shown) functions to adjust a height of the microscope 230 and thus a focus of the object lens to inspect defects of the wafers 222 and 223, in the present invention, the focus of the object lens can be adjusted by the six-axis robot 270. That is, in the present invention, the six-axis robot 270 can perform function of the object lens. The eye lens 235 is a tool for allowing the operator 240 to observe the wafers 222 and 223. [43] The micro inspection part 280 disposes the wafer 222 under the object lens 231 of the microscope 230, and then, magnifies and observes defects of the wafer 222, which are not seen by a human's eye, using the object lens 231 of the microscope 230, such that defects such as foreign substances, cracks, bad patterns, and so on, on a pattern designed on the wafer 222 can be observed and accurately inspected through the eye lens 235.

[44] The six-axis robot 270 is a robot capable of moving forward, backward, leftward and rightward depending on the size of the wafer accommodated in the cassette mounting part. The six-axis robot 270 unloads the wafer 220 accommodated in the cassette 210, and then, moves the wafer 220 to the macro inspection part 250 or the micro inspection part 280, or loads the wafer 221 or 222 located at the macro inspection part 250 or the micro inspection part 280 into the cassette 210.

[45] In addition, the six-axis robot 270 moves and rotates the arm, which grips the wafer

220, 221, or 222, depending on inspection conditions required for the macro inspection part 250 or the micro inspection part 280. The arm will be described below with reference to FIG. 6.

[46] For example, the six-axis robot 270 can move the wafer 221 inspected by the macro inspection part 250 to the micro inspection part 280, or move the wafer 222 inspected by the micro inspection part 280 to the macro inspection part 250. In addition, the six- axis robot 270 can invert or rotate the wafer 221 upward, downward, forward, backward, leftward and rightward upon macro inspection of the wafer 221 located at the macro inspection part 250. Further, the six-axis robot 270 can accurately rotate the wafer 222 upward, downward, forward, backward, leftward and rightward upon micro inspection of the surface of the wafer 222 located at the micro inspection part 280.

[47] Meanwhile, the gripped state as described above means that the wafer 221 or 222 can be moved and rotated without damage, and also means that the wafer is vacuum sucked by a wafer holder of the six-axis robot, which will be described.

[48] The wafer inspection apparatus 200 in accordance with the present invention may further include a side inspection part 290.

[49] When the wafer 223 is disposed by the side of the object lens 231, the side inspection part 290 magnifies and observes side defects of the wafer 223, which cannot be seen by the operator's eyes, using the microscope 230 to inspect side defects of the wafer 223.

[50] Here, the wafer 223 locates at the side inspection part 290 is the wafer moved after the wafer 220 accommodated in the cassette 210 is unloaded by the six-axis robot 270. In addition, the wafer 224 located at the side inspection part 290 may be loaded into the cassette 210 by the six-axis robot 270 after wafer side inspection. Further, the wafer 224 located at the side inspection part 290 may be the wafer 221 or 222 conveyed from the macro inspection part 250 or the micro inspection part 280 by the six-axis robot 260.

[51] Meanwhile, specific structure of the six-axis robot 270 will be described with reference to FIGS. 6 and 7.

[52] FIGS. 6 and 7 are views showing structure of a six-axis robot used in the wafer inspection apparatus in accordance with an exemplary embodiment of the present invention.

[53] Referring to FIG. 6, the six-axis robot 270 in accordance with an exemplary embodiment of the present invention may employ an articulate robot having six degrees of freedom, which includes a base part 271, a rotation drive part 272, a first arm 273, a second arm 274, a third arm 275, and a wafer holder 276.

[54] The base part 271 is fixedly installed at the wafer inspection apparatus 200. The rotation drive part 272 is installed on the base part 271 to be rotated with respect to a substantially vertical rotary shaft. The first arm 273 is connected to the rotation drive part 272 to be pivoted with respect to a shaft perpendicular to a longitudinal direction thereof. The second arm 274 is connected to an end of the first arm 273, which is not connected to the rotation drive part 272, to be pivoted with respect to a shaft perpendicular to a longitudinal direction thereof. The other end of the second arm 274 is rotatable with respect to a longitudinal direction thereof. The third arm 275 is connected to the other end of the second arm 274 to be pivoted with respect to a shaft perpendicular to a longitudinal direction thereof.

[55] Here, a pivot shaft of the second arm 274 may be parallel to a pivot shaft of the third arm 275. An end of the third arm 275, far from the second arm 274, is rotatable with respect to a longitudinal shaft thereof. In addition, the wafer holder 276 is connected to the end of the third arm 275, far from the second arm 274. The wafer holder 276 will be described below with reference to FIG. 7.

[56] Referring to FIG. 7, the wafer holder 276 in accordance with an exemplary embodiment of the present invention includes a first air injection port 276a, an alignment 276b, and a reference pin 276c. In addition, the wafer holder 276 may further include a wafer rotation unit 277 installed at one end thereof.

[57] The wafer holder 276 can safely seat the wafer 224, and the respective arms 273, 2

74 and 275 of the six-axis robot 270 can move the wafer 224 upward, downward, leftward, rightward, forward and backward. When the wafer 224 is seated on the wafer holder 276, air injected through the first air injection port 276a of the wafer holder 276 prevents the wafer 224 from being in contact with the wafer holder 276. At this time, the first air injection port 276a may be installed at a surface of the wafer holder 276, adjacent to the wafer, in plural.

[58] In addition, the wafer holder 276 may have a U-shape or a V-shape, but not limited thereto, may have any shape under the condition of safely seating the wafer 224. The wafer holder 276 may be formed of a transparent material, preferably, formed of any one of transparent engineering plastic, a carbon nano rube material, and glass. The reason for forming the wafer holder 276 using the transparent material is that the wafer 224 is rotated in a gripped state to enable visual inspection of the wafer 224.

[59] Further, the wafer holder 276 can center the wafer 224 using the alignment 276b, and determine a reference of the wafer 224 using the reference pin 276c.

[60] The wafer rotation unit 277 should be rotated clockwise or counterclockwise, independently from the wafer holder 276, and should be adjusted upward and downward such that the wafer 224 is not in contact with the wafer holder 276 upon rotation thereof.

[61] The wafer rotation unit 277 includes a first air suction port 277a formed at a substantially center part thereof to rotate the wafer 224 in a gripped state. Therefore, when the wafer 224 is seated on an upper end of the wafer rotation unit 277, the wafer 224 is vacuum sucked by a suction pressure introduced through the first air suction port 277a of the wafer rotation unit 277, and air is injected through the first air injection port 276a of the wafer holder 276 to float the wafer 224 over the wafer holder 276 such that the wafer 224 is not in contact with the wafer holder 276 even though the wafer rotation unit 277 is finely rotated upward, downward, leftward and rightward. At this time, since the wafer 224 is vacuum sucked by the first air suction port 277a of the wafer rotation unit 277, the wafer 224 cannot be separated from the wafer rotation unit 277 and the wafer holder 276 even though the wafer 224 is rotated.

[62] Therefore, when the wafer is rotated, the wafer holder 276 and the wafer rotation unit 277 can perform an auto-focusing operation to adjust a position of the wafer 224 with respect to the microscope 230.

[63] As described above, the six-axis robot of the present invention can vertically and laterally move and rotate the wafer through six degrees of freedom thereof, and can freely convey the wafer gripped by an air pressure without droppage.

[64] Hereinafter, a method of inspecting a wafer using a wafer inspection apparatus including a six-axis robot will be described. The method of inspecting a wafer using a wafer inspection apparatus including a six-axis robot in accordance with the present invention includes (a) unloading a wafer from a cassette; (b) illuminating front and rear surfaces of the wafer disposed at various positions in a state that the wafer is gripped by the six-axis robot and visually inspecting the wafer; (c) accurately inspecting the wafer gripped by the six-axis robot through a microscope; and (d) loading the wafer, in which inspection is completed, into the cassette. In addition, the method further includes (e) inspecting a side surface of the wafer, and (f) performing automated optical inspection (AOI) for inspecting a pattern defect of the wafer. [65] The method will be described with reference to FIGS. 8 to 14. Specifically, the macro inspection of the wafer by the (b) step will be described with reference to FIGS. 8 and 9, and the micro inspection of the wafer by the (c) step will be described with reference to FIGS. 10 to 12. In addition, the side inspection of the wafer by the (e) step will be descried with reference to FIG. 13, and the AOI of the wafer by the (f) step will be described with reference to FIG. 14. The (a) and (d) steps correspond to steps commonly applied to the inspections described above.

[66] First, a process of performing the macro inspection of the wafer conveyed to inspect wafer defects will be described with reference to FIGS. 8 and 9.

[67] FIGS. 8 and 9 are views showing a macro inspection process of inspecting defects of a wafer using the wafer inspection apparatus in accordance with an exemplary embodiment of the present invention, wherein FIG. 8 is a plan view of the wafer inspection apparatus upon macro inspection, and FIG. 9 is a left side view of the wafer inspection apparatus upon macro inspection.

[68] First, a wafer 220 disposed in a cassette 210 is gripped by a six-axis robot 270 to be unloaded from the cassette 210 and conveyed to a macro inspection part 250. At this time, the wafer 220 is vacuum sucked by a first air suction port 277a of a wafer rotation unit 277 to be securely gripped at an upper end of a wafer holder 276 and the wafer rotation unit 277.

[69] Illumination light is irradiated to a surface of a wafer 221 from an illumination device 251, and an operator 240 visually inspects defects of the wafer 221 such as foreign substances, cracks, inferior patterns, and so on.

[70] Then, in order to inspect a rear surface of the wafer 221, arms 273, 274 and 275 of the six-axis arm 270 are rotated to invert the wafer sucked by the first air suction port 277a of the wafer rotation unit 277 such that a lower surface of the wafer 221 is directed upward. Next, the vacuum sucked wafer 221 is rotated by the wafer holder 277 upward, downward, forward, backward, leftward and rightward such that another part of the wafer 221 can be seen by the operator 240 or light from the illumination device 251 is irradiated at another angle to perform inspection of the wafer 221.

[71] After that, the wafer 221, macro inspection of which is completed, is loaded into the cassette 210 or conveyed to a micro inspection part 280 or a side inspection part 290.

[72] Meanwhile, since the six-axis robot 270 has six degrees of freedom, and includes a first arm 273, a second arm 274, and a third arm 275, the six-axis robot 270 has a wide range of moving line as shown by 262 of FIG. 8. In addition, a base part 271 and a rotation drive part 272 corresponding to a body of the six-axis robot 270 have a moving line with a radius of rotation as shown by 260 of FIG. 8. Further, the first arm 273, the second arm 274, and the third arm 275 of the six-axis robot 270 have a moving line as shown by 261 of FIG. 8. Therefore, the wide range of moving line 262 can improve space utilization of the wafer inspection apparatus 200 as well as reduce a tact time thereof by rapidly loading, unloading and moving the wafer 221.

[73] FIGS. 10 to 12 are views showing a micro inspection process of inspecting defects of a wafer using the wafer inspection apparatus and the six-axis robot in accordance with an exemplary embodiment of the present invention, wherein FIG. 10 is a front view of the wafer inspection apparatus upon micro inspection, FIG. 11 is a plan view of the wafer inspection apparatus upon micro inspection, and FIG. 12 is a right side view of the wafer inspection apparatus.

[74] FIGS. 10 to 12 illustrate that the wafer 220 accommodated in the cassette 210 is conveyed under an object lens 231 of the microscope 230 by the six-axis robot 270. After completion of the macro inspection, the wafer 220 can be gripped by the wafer holder 276 of the six-axis robot 270 to be moved from the macro inspection part 250.

[75] A space 233 under the microscope 230 is a space in which the wafer can freely move. While the conventional inspection apparatus should have a stage movable in X-, Y- and Z-axis directions to support a wafer in this space 233 and vary disposition of the wafer depending on inspection conditions, the six-axis robot of the wafer inspection apparatus in accordance with the present invention can perform such functions to remove necessity of the conventional stage.

[76] First, the wafer 220 disposed in the cassette 210 or the wafer 221 disposed on the macro inspection part 250 is gripped by the six-axis robot 270 to be unloaded or moved to the micro inspection part 280. At this time, the wafer 220 to be unloaded or moved is vacuum sucked by the first air suction port 277a of the wafer rotation unit 277 to be gripped by the wafer holder 276.

[77] Then, the wafer 222 loaded onto the micro inspection part 280 is rotated by the wafer holder 276 to be auto-focused to a focus of the object lens 231. The auto- focusing may be performed by vertically moving the microscope 230. Therefore, the operator 240 can accurately inspect defects of the wafer 222 such as foreign substances, cracks, inferior patterns, and so on, which cannot be seen by the operator, through an eye lens 235.

[78] Next, the wafer 222, the micro inspection of which is completed, is loaded into the cassette 210, or provided for another inspection.

[79] FIG. 13 is a front view showing a side inspection process of inspecting side defects of a wafer using the wafer inspection apparatus and the six-axis robot in accordance with an exemplary embodiment of the present invention.

[80] Referring to FIG. 13, the wafer 220 disposed in the cassette 210 or the wafer 221 or

222 disposed on the macro inspection part 250 is gripped by the six-axis robot 270 to be moved to the side inspection part 290. At this time, the wafer 220 or 221 is vacuum sucked by the first air suction port 277a of the wafer rotation unit 277 to be gripped on the wafer holder 276. Here, since the space 233 under the microscope 230 is empty, the six-axis robot 270 can grip the wafer 233 to locate the wafer 233 under the object lens 231.

[81] Then, the wafer 223 loaded or moved to the side inspection part 290 is rotated by the wafer holder 276 to 90° such that a side surface of the wafer 223 is auto-focused to a focus of the object lens 231. The auto-focusing may be performed by moving the arms 273, 274 and 275 of the six-axis robot 270 or moving the object lens 231 of the microscope 230.

[82] In order to inspect the side surface of the wafer 223, the wafer rotation unit 277 rotates the wafer 221 sucked by the first air suction port 277a to 90° to inspect the entire side surface.

[83] Therefore, the operator 240 can observe side defects of the wafer enlarged by the object lens 231, which cannot be seen by the operator 240, to inspect the side defects of the wafer. At this time, the object lens 231 can enlarge the side surface of the wafer 223 with low magnification.

[84] Then, the wafer 223, the side inspection of which is completed, is moved to the macro inspection part 250 or loaded into the cassette 210.

[85] In the wafer inspection method in accordance with an exemplary embodiment of the present invention, while the macro inspection, the micro inspection, and the side inspection can be readily performed using the six-axis robot, but not limited thereto, another inspection may be performed. For example, automated optical inspection (AOI) may be further performed.

[86] FIG. 14 is a front view showing an AOI process of inspecting pattern defects of a wafer using the wafer inspection apparatus and the six-axis robot in accordance with an exemplary embodiment of the present invention.

[87] FIG. 14 shows a portion of FIG. 10, the microscope 230 of FIG. 10 further including a camera 236. While the conventional method inspects a wafer using a separate AOI apparatus to output inspected pattern defects of the wafer as data of X and Y coordinates and a micro inspection apparatus receives the output pattern defects data to perform micro inspection, the embodiment of the present invention can perform the AOI using the six-axis robot 270.

[88] That is, when a line sensor camera 236 is attached to the microscope 230, the six- axis robot 270 locates the wafer 224, which is gripped by the wafer holder 276, under the object lens 231 via a space under the line sensor camera 236 in order to perform the AOI. At this time, the wafer 224 passing under the camera 236 is finely moved by the six-axis robot 270 in vertical and lateral directions to accurately photographs pattern defects of the wafer 224. Then, the operator 240 accurately inspects the pattern defects of the wafer 224 photographed through the eye lens 235 during micro inspection. [89] Therefore, it will be apparent to those skilled in the art that another modification may be performed without departing from the technical sprit or essential features of the present invention.

[90] The forgoing description concerns an exemplary embodiment of the invention, is intended to be illustrative, and should not be construed as limiting the invention. Many alternatives, modifications, and variations within the scope and spirit of the present invention will be apparent to those skilled in the art.

Claims

[1] An apparatus for inspecting a wafer comprising: a cassette mounting part for fixing a cassette in which a wafer is accommodated; a macro inspection part for visually inspecting front and rear surfaces of the wafer illuminated by an illumination device; a micro inspection part for accurately inspecting defects of the wafer using a microscope; and a six-axis robot for unloading the wafer from the cassette disposed at the cassette mounting part or loading the cassette thereinto, and moving and rotating the wafer in a gripped state depending on inspection conditions required by the macro inspection part or the micro inspection part.

[2] The apparatus for inspecting a wafer according to claim 1, wherein the six-axis robot comprises: a base part fixed to the wafer inspection apparatus; a rotation drive part rotatably installed on the base part; a first arm, a first end of which is connected to the rotation drive part, pivotable with respect to a shaft perpendicular to its longitudinal shaft within a predetermined angle range; a second arm, a first end of which is connected to a second end of the first arm, pivotable with respect to a shaft perpendicular to the longitudinal shaft of the first arm, and rotatable with respect to its longitudinal shaft; a third arm, a first end of which is connected to a second end of the second arm, pivotable with respect to a shaft perpendicular to the longitudinal shaft of the second arm, and rotatable with respect to its longitudinal shaft; and a wafer holder connected to a second end of the third arm, and seating the wafer.

[3] The apparatus for inspecting a wafer according to claim 2, wherein the six-axis robot is fixed or movable in forward, backward, leftward and rightward directions.

[4] The apparatus for inspecting a wafer according to claim 2, wherein the six-axis robot further comprises a wafer rotation unit for rotating the wafer in a gripped state.

[5] The apparatus for inspecting a wafer according to claim 2, wherein the wafer holder is formed of a transparent material.

[6] The apparatus for inspecting a wafer according to claim 5, wherein the wafer holder is formed of any one of transparent engineering plastic, a carbon nano tube material, and glass.

[7] The apparatus for inspecting a wafer according to any one of claims 2 to 6, wherein the wafer holder has a substantially U shape.

[8] A method of inspecting a wafer using a wafer inspection apparatus including a six-axis robot comprising:

(a) unloading a wafer from a cassette;

(b) illuminating front and rear surfaces of the wafer disposed at various positions in a state that the wafer is gripped by the six-axis robot and visually inspecting the wafer;

(c) accurately inspecting the wafer gripped by the six-axis robot through a microscope; and

(d) loading the wafer, in which inspection is completed, into the cassette.

[9] The method of inspecting a wafer using a wafer inspection apparatus including a six-axis robot according to claim 8, further comprising (e) rotating and gripping the wafer in a state that the wafer is vertically stood by the six-axis robot, and then, inspecting side defects of the wafer.

[10] The method of inspecting a wafer using a wafer inspection apparatus including a six-axis robot according to claim 8, wherein the microscope comprises a line sensor camera, the method further comprises (f) inspecting (AOI) pattern defects of the wafer by passing the wafer under the line sensor camera in a state that the wafer is gripped by the six-axis robot.

[11] The method of inspecting a wafer using a wafer inspection apparatus including a six-axis robot according to claim 8, wherein the six-axis robot comprises: a base part fixed to the wafer inspection apparatus; a rotation drive part rotatably installed on the base part; a first arm, a first end of which is connected to the rotation drive part, pivotable with respect to a shaft perpendicular to its longitudinal shaft within a predetermined angle range; a second arm, a first end of which is connected to a second end of the first arm, pivotable with respect to a shaft perpendicular to the longitudinal shaft of the first arm, and rotatable with respect to its longitudinal shaft; a third arm, a first end of which is connected to a second end of the second arm, pivotable with respect to a shaft perpendicular to the longitudinal shaft of the second arm, and rotatable with respect to its longitudinal shaft; and a wafer holder connected to a second end of the third arm, and seating the wafer.

[12] The method of inspecting a wafer using a wafer inspection apparatus including a six-axis robot according to claim 11, wherein the six-axis robot is fixed or movable in forward, backward, leftward and rightward directions.

[13] The method of inspecting a wafer using a wafer inspection apparatus including a six-axis robot according to claim 11, wherein the six-axis robot further comprises a wafer rotation unit for rotating the wafer in a gripped state. [14] The method of inspecting a wafer using a wafer inspection apparatus including a six-axis robot according to claim 11, wherein the wafer holder is formed of a transparent material. [15] The method of inspecting a wafer using a wafer inspection apparatus including a six-axis robot according to claim 14, wherein the wafer holder is formed of any one of transparent engineering plastic, a carbon nano tube material, and glass. [16] The method of inspecting a wafer using a wafer inspection apparatus including a six-axis robot according to any one of claims 9 to 15, wherein the wafer holder has a substantially U shape.