JP5235509B2 - Wafer positioning device and table in wafer positioning device - Google Patents

Description

  The present invention relates to a wafer positioning apparatus for positioning a semiconductor wafer and a table used in such a wafer positioning apparatus.

  In the semiconductor manufacturing field, wafers tend to increase in size year by year, and wafers are becoming thinner to increase mounting density. In order to thin the wafer, back grinding (back surface grinding) is performed to grind the back surface of the semiconductor wafer. At the time of back grinding, a surface protective film is attached to the surface of the wafer in order to protect the semiconductor elements formed on the wafer surface.

When the back surface grinding is completed, the wafer is supplied to a peeling unit for peeling the surface protective film. In the peeling unit, the wafer is aligned by an alignment device. As disclosed in Patent Document 1, at the time of alignment, the wafer is placed on a stage having a smaller diameter than the wafer. And a light source and a light receiving sensor are arrange | positioned so that the outer peripheral part of a wafer may be pinched | interposed. Thereafter, the stage is rotated to scan the wafer, whereby the center of the wafer is obtained, and then the wafer is aligned based on a notch or an orientation flat (hereinafter referred to as “notch or the like”) on the outer periphery of the wafer. .
JP 2006-237501 A

  However, since the thickness of the wafer is reduced by backside grinding, the outer peripheral portion of the wafer hangs down from the stage when the stage is smaller than the wafer. For this reason, a notch or the like of the wafer cannot be accurately detected, and as a result, the wafer cannot be accurately aligned.

  Furthermore, since the rigidity of the back-ground wafer is small, there is a risk that if the outer peripheral portion of the wafer hangs down from the stage, the outer peripheral portion of the wafer may be cracked, chipped, cracked or the like (hereinafter referred to as “crack etc.”). There is sex.

  By the way, in order to prevent the outer peripheral portion of the wafer from sagging, it is also conceivable to place the wafer on a stage larger than the wafer. In this case, since the light source and the light receiving sensor cannot be used, the wafer is imaged using the epi-illumination. Next, notches and the like in the captured image of the wafer are identified, and thereby the wafer is aligned by a known method.

  FIG. 4 is a partially enlarged view of a table of a wafer positioning apparatus in the prior art. A holding portion 120 made of a porous material is embedded in the upper surface of the table 100 shown in FIG. The holding unit 120 is connected to the vacuum source 150, and when the vacuum source 150 is driven, the wafer 20 is sucked and held by the holding unit 120. As can be seen from FIG. 4, the surface protective film 3 is attached to the surface 21 of the wafer 20. A chamfer 26 is formed at the edge of the wafer 20.

  However, since the wafer 20 is usually cleaned after back grinding and placed on the positioning device, the cleaning liquid L may remain in the gap between the surface protective film 3 and the chamfered portion 26 and in the vicinity thereof. is there. In particular, the liquid tends to remain near the notch of the wafer 20. For this reason, it becomes difficult to distinguish notches and the like of the wafer from the captured image, and accurate alignment of the wafer cannot be performed.

  The present invention has been made in view of such circumstances, and even a wafer after backside grinding in which a cleaning liquid remains can be positioned accurately without causing cracks or the like. It is an object to provide an apparatus and a table for use in such a wafer positioning apparatus.

In order to achieve the above-mentioned object, according to the first invention, a holding means for sucking and holding a wafer, a table that is larger than the wafer held by the holding means and provided with the holding means, A liquid discharging means for discharging the liquid attached around the wafer held by the holding means, an annular wall provided between the holding means and the liquid discharging means, and a driving means for rotating the table; Imaging means for picking up an image of a detection portion for positioning located on the peripheral portion of the wafer using epi-illumination , wherein the liquid discharge means is formed of a porous material, and the holding means of the table The liquid discharge means has an outer diameter larger than the outer diameter of the wafer held by the holding means, and the liquid discharge means has an inner diameter at the holding means. Was set to less than the outer diameter of the lifting has been the wafer, the wafer positioning device is provided.

That is, in the first invention, since the table is larger than the wafer, the outer peripheral portion of the wafer does not hang down from the table even if the wafer is thin. Therefore, the wafer can be stably held on the table without causing cracks or the like. Further, the liquid, for example, the cleaning liquid is discharged by the liquid discharge unit. Therefore, the detection part of the wafer, for example, a notch or the like in the captured image does not become difficult to identify with the liquid. Thus, the wafer can be accurately positioned based on the detection site in the image. Further, since the liquid is absorbed by the liquid discharge portion made of the porous material, the liquid can be prevented from remaining on the table.

According to a second aspect, in the first aspect , the liquid discharging means is black or black.
That is, in the second invention, since the wafer is recognized as silver in the captured image, the detection part of the wafer can be easily detected with respect to the black liquid discharge portion. The imaging means is, for example, a CCD camera.

According to a third aspect, in the first or second aspect , the apparatus further comprises a vacuum means for liquid discharge means connected to the liquid discharge means.
That is, in the third invention, the liquid adhering to the liquid discharge portion can be forcibly discharged.

According to a fourth invention, in the third invention, further comprising a holding means vacuum means connected to the holding means, wherein the liquid discharging means vacuum means and the holding means vacuum means are individually provided. Made to work.
In the case where the wafer is held and the liquid is discharged only by the holding unit vacuum means, a vacuum leak may occur. However, in the fourth invention, the vacuum leak occurs and the wafer is not held by the holding unit. Can be prevented.

According to a fifth aspect of the invention, the table in the wafer positioning apparatus, and holding means for holding by suction the wafer, and the liquid discharge means for discharging the liquid adhering to the wafer around held by the holding means, wherein An annular wall provided between the holding means and the liquid discharging means, and a driving means for rotating the table , wherein the liquid discharging means is formed of a porous material and the holding means of the table The liquid discharge means has an outer diameter larger than an outer diameter of the wafer held by the holding means, and an inner diameter of the liquid discharge means is held by the holding means. A table is provided that is smaller than the outer diameter of the wafer . In the fifth aspect, the same effect as in the first aspect can be obtained.

According to a sixth aspect, in the fifth aspect , the liquid discharging means is black or black. In the sixth invention, the same effect as in the second invention can be obtained.

According to a seventh invention, in the fifth or sixth invention, the liquid ejecting means vacuum means connected to the liquid ejecting means is further provided. In the seventh invention, the same effect as in the third invention can be obtained.

According to an eighth invention, in the seventh invention, further comprising a holding means vacuum means connected to the holding means, wherein the liquid discharging means vacuum means and the holding means vacuum means are individually provided. Made to work. In the eighth invention, the same effect as in the fourth invention can be obtained.

Embodiments of the present invention will be described below with reference to the accompanying drawings. In the following drawings, the same members are denoted by the same reference numerals. In order to facilitate understanding, the scales of these drawings are appropriately changed.
FIG. 1 is a side sectional view of a wafer positioning apparatus according to the present invention, and FIG. 2 is a top view of the table shown in FIG. FIG. 3 is a partially enlarged view of the table of the wafer positioning apparatus according to the present invention.

  The table 10 of the wafer positioning apparatus 1 shown in these drawings is configured to be rotatable around a rotary shaft portion 18 extended by a motor 33. Further, an imaging camera 32, for example, a CCD camera is installed above the table 10. The imaging camera 32 captures the reflected image of the wafer 20 held by the holding unit 12 (described later) of the table 10 using epi-illumination. As shown in FIG. 1, the motor 33 and the imaging camera 32 are connected to a control device 31, for example, a digital computer.

  As shown in FIGS. 1 and 2, a circular holding unit 12 that holds the wafer 20 is provided at the center of the table 10. The outer diameter of the holding unit 12 is smaller than the outer diameter of the wafer 20. The holding part 12 is made of a porous material, for example, porous alumina. As shown in the drawing, the holding portion 12 is fitted into the recess 12 a of the table 10 so that the top surface thereof is flush with the upper surface of the table 10. Further, as shown in FIG. 3, the first vacuum source 15 is connected to the recess 12 a through the conduit 35. Therefore, when the first vacuum source 15 is activated, a suction action is generated on the top surface of the holding unit 12 to suck and hold the wafer 20.

  As shown in FIGS. 1 and 2, an annular step portion 13a is formed along the outer peripheral portion of the table 10, and an annular liquid discharge portion 13 is fitted into the step portion 13a. The liquid discharge part 13 is formed from a porous material, for example, porous alumina. The pores of the liquid discharge part 13 are preferably coarser than the holding part 12.

In addition, as shown in FIG. 3, the top surface of the liquid discharge unit 13 is flush with the top surface of the table 10. The outer diameter of the liquid discharge unit 13 is larger than the outer diameter of the wafer 20, and the inner diameter of the liquid discharge unit 13 is smaller than the outer diameter of the wafer 20 .

  Furthermore, in the embodiment shown in FIG. 3, the outer peripheral surface of the liquid discharge part 13 is exposed. For this reason, the liquid adhering to the upper surface of the liquid discharge part 13, for example, washing water, is absorbed by the liquid discharge part 13 by gravity and discharged from the outer peripheral surface through the liquid discharge part 13.

  As shown in the figure, an annular wall portion 19 is provided between the holding portion 12 and the liquid discharge portion 13. Therefore, when the first vacuum source 15 is activated, air is not sucked into the first vacuum source 15 through the outer peripheral surface of the liquid discharge unit 13.

  When the wafer positioning apparatus 1 is used, the wafer 20 is placed on the table 10 of the wafer positioning apparatus 1. A semiconductor chip (not shown) is formed on the surface 21 of the wafer 20. In order to protect these semiconductor chips, it is assumed that the surface protective film 3 is pasted on the surface 21 of the wafer 20 in advance.

  The back surface of the wafer 20 is ground from the initial back surface 22 'to the back surface 22 after grinding by a back surface grinding device (not shown). Further, as described above, the back-ground ground wafer 20 is previously cleaned with cleaning water. Therefore, the cleaning water adheres to the wafer 20 supplied to the wafer positioning apparatus 1.

  When such a wafer 20 is placed on the table 10, the first vacuum source 15 is activated and the wafer 20 is held by the holding unit 12. Since the table 10 is larger than the wafer 20, the outer peripheral portion of the wafer 20 does not hang down from the table 10 even when the wafer 20 is ground back and has a small thickness. Therefore, in the present invention, the wafer 20 is not cracked and the wafer 20 is stably held.

  As can be seen from FIG. 3, when the wafer 20 is held by the holding unit 12, the outer peripheral portion of the wafer 20 is positioned in the region of the liquid discharge unit 13. When the wafer 20 is held by the holding unit 12, the liquid adhering to the vicinity of the outer peripheral portion of the wafer 20 descends due to gravity, is sucked into the liquid discharge unit 13, and is discharged from the outer peripheral surface of the liquid discharge unit 13. Accordingly, the liquid adhering to the vicinity of the outer peripheral portion of the wafer 20, particularly the vicinity of the notch 29 of the wafer 20 is excluded from the wafer 20.

  For this purpose, a second vacuum source 16 may be connected to the liquid outlet 13 (see FIG. 3). In this case, the liquid near the outer periphery of the wafer 20 is forcibly excluded. Further, a trap 37 may be disposed in the pipe line 36 to prevent the liquid from being directly sucked into the second vacuum source 16.

  When the liquid is removed from the outer peripheral portion of the wafer 20, the imaging camera 32 captures an image of the entire wafer 20. The control device 31 processes the captured image and identifies the position of the notch 29 and the like of the wafer 20 with respect to the liquid discharge unit 13. As described above, since the liquid in the vicinity of the outer peripheral portion of the wafer 20 has already been removed, the position of the notch 29 and the like can be easily detected with respect to the liquid discharge portion 13 of the table 10 in the present invention.

  In order to easily recognize the position of the notch 29 and the like of the wafer 20 with respect to the liquid discharge unit 13, the liquid discharge unit 13 is preferably black or black. The reason is that, in the image captured by the imaging camera 32, the back surface 22 after grinding of the wafer 20 is recognized by silver or a silver system, so that the silver wafer 20 can be easily removed from the black liquid discharge unit 13. This is because they can be identified. Thereafter, the control device 31 rotates the table 10 through the motor 33 based on the identified position of the notch 29 and the like, and positions the notch 29 and the like of the wafer 20 at a desired position.

  As described above, in the present invention, since the image of the wafer 20 is taken after the liquid is discharged by the liquid discharge unit 13, the notch 29 and the like of the wafer 20 are easily detected. Then, the table 10 is rotated based on the detected notch 29 and the like, thereby enabling the wafer 20 to be accurately positioned at a desired position.

1 is a sectional side view of a wafer positioning device according to the present invention. FIG. 2 is a top view of the table shown in FIG. 1. It is the elements on larger scale of the table of the wafer positioning device based on this invention. It is the elements on larger scale of the table of the wafer positioning device in a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Wafer positioning device 3 Surface protective film 10 Table 12 Holding part 12a Recessed part 13 Liquid discharge part 13a Step part 15 First vacuum source 16 Second vacuum source 18 Rotating shaft part 19 Annular wall part 20 Wafer 21 Surface 22 Back surface 26 after grinding Take part 29 Notch 31 Control device 32 Imaging camera (imaging means)
33 Motor (drive means)
35 pipeline 36 pipeline 37 trap

Claims (8)

Holding means for sucking and holding the wafer;
A table larger than the wafer held by the holding means and provided with the holding means;
Liquid discharging means for discharging the liquid adhering around the wafer held by the holding means;
An annular wall provided between the holding means and the liquid discharge means;
Driving means for rotating the table;
An image pickup means for picking up an image of a detection portion for positioning in the peripheral portion of the wafer using epi-illumination,
The liquid discharge means is made of a porous material and is provided around the holding means of the table, and the outer diameter of the liquid discharge means is larger than the outer diameter of the wafer held by the holding means. A wafer positioning apparatus that is large and has an inner diameter that is smaller than an outer diameter of the wafer held by the holding means.   The wafer positioning apparatus according to claim 1, wherein the liquid discharging means is black or black.   The wafer positioning apparatus according to claim 1, further comprising a vacuum means for liquid discharge means connected to the liquid discharge means. 4. The wafer positioning apparatus according to claim 3, further comprising a holding means vacuum means connected to the holding means, wherein the liquid discharging means vacuum means and the holding means vacuum means are individually operated. . In a table in a wafer positioning device,
Holding means for sucking and holding the wafer;
Liquid discharging means for discharging the liquid attached around the wafer held by the holding means;
An annular wall provided between the holding means and the liquid discharge means;
Driving means for rotating the table,
The liquid discharge means is made of a porous material and is provided around the holding means of the table, and the outer diameter of the liquid discharge means is larger than the outer diameter of the wafer held by the holding means. A table that is large and has an inner diameter that is smaller than an outer diameter of the wafer held by the holding means.   The table according to claim 5, wherein the liquid discharging means is black or black.   Furthermore, the table of Claim 5 or 6 provided with the vacuum means for liquid discharge means connected to the said liquid discharge means. 8. The table according to claim 7, further comprising holding means vacuum means connected to the holding means, wherein the liquid discharging means vacuum means and the holding means vacuum means are individually operated.

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