TWI653677B - Alignment method - Google Patents

Abstract

An object of the present invention is to provide an alignment method capable of performing alignment with high precision even in a workpiece having a small number of exposed main patterns. The solution is to include a configuration including a positional relationship registration step and an automatic θ matching step. In the positional relationship registration step, the first main object is held by the holding table, and the direction of the first divided line is adjusted to be parallel to the X-axis direction, and then the coordinates (X1, Y1) of the first main pattern and the second main are performed. The coordinates (X2, Y2) of the pattern are registered as the coordinate information in the control means, and the positional relationship between the coordinates of the first main pattern and the coordinates of the second main pattern (X2-X1, Y2-Y1) is obtained and registered in the control means. in. In the automatic θ matching step, the second workpiece is held by the holding table, and the first main pattern and the second main pattern of the second workpiece are detected based on the registered coordinate information, and the holding table is rotated to correspond to the first 1 positional relationship between the coordinates (X1', Y1') of the main pattern and the coordinates (X2', Y2') of the second main pattern (X2'-X1', Y2'-Y1') and the positional registration step The amount of difference in the registered positional relationship (X2-X1, Y2-Y1).

Description

Alignment method Field of invention

The present invention relates to an alignment method for adjusting a direction or the like of a workpiece with respect to a cutting device.

Background of the invention

In recent years, the WL-CSP (Wafer Level Chip Size Package) that has been in the state of wafers to package has been attracting attention. The WL-CSP is provided on the front side of the device formed on the wafer, and is provided with a rewiring layer and an electrode, sealed with a resin or the like, and then the sealed wafer (WL-CSP substrate) is divided by a method such as cutting. Since this WL-CSP forms the size of the package as it is, the size of the divided wafer is useful for miniaturization of the package.

However, when cutting a workpiece such as a wafer, alignment of the direction of the workpiece or the like is generally performed based on the main pattern having characteristics in the element. On the other hand, in the above WL-CSP substrate, most of the elements are covered with a resin or the like, and the main pattern exposed is small. Therefore, the conventional method cannot properly align a workpiece such as a WL-CSP substrate.

In response to this problem, a method of using a solder ball or the like that is exposed on the upper surface of the sealing resin and functions as an electrode has been used as a target pattern (see For example, Patent Document 1) is proposed based on the intersection of the planned dividing line and the outer peripheral edge exposed on the outer peripheral portion of the workpiece (see, for example, Patent Document 2). According to these methods, alignment can be performed even on a workpiece such as a WL-CSP substrate having a small main pattern exposed.

Prior technical literature Patent literature

Patent Document 1: Japanese Patent Laid-Open Publication No. 2013-171990

Patent Document 2: Japanese Patent Laid-Open Publication No. 2013-74021

Summary of invention

However, there are individual differences in the shape, size, and the like of the solder balls used in the above method, and the intersection of the planned dividing line and the outer peripheral edge is not necessarily clear. Therefore, in the above method, there is a problem that alignment with high precision cannot be easily realized.

The present invention has been made in view of the above problems, and an object of the invention is to provide an alignment method capable of performing alignment with high precision even in a workpiece having a small number of exposed main patterns.

According to the alignment method provided by the present invention, in order to form elements in respective regions on the front side side which are divided by a plurality of intersecting predetermined lines by using a cutting device, and to separate the respective divided dividing lines from each other, The first main pattern and the second main pattern are exposed to the workpiece exposed on the front side, and the alignment method is performed by the first main pattern and the second main pattern, wherein the cutting device is provided with the workpiece to be processed a rotatable holding table, a cutting means for cutting a workpiece held by the holding table by a cutting blade, a machining feeding means for machining the holding table in the X-axis direction, and the cutting means in the Y-axis direction The indexing feeding means for the upper index feeding, the conveying means for conveying the workpiece to the holding table within the allowable error range, and the control means for controlling the respective constituent elements. The alignment method includes a positional relationship registration step of holding the first workpiece by the holding table, and the operator adjusts the direction of the division line to the X axis by rotating the holding table by a predetermined amount. After the directions are parallel, the coordinates (X1, Y1) of the first main pattern and the coordinates (X2, Y2) of the second main pattern are registered as coordinate information in the control means, and the first main pattern is obtained. The coordinate relationship between the coordinates and the coordinates of the second main pattern (X2-X1, Y2-Y1) is registered in the control means; and the automatic θ matching step, after the positional relationship registration step, the second means by the transfer means The workpiece is transported to the holding table to be held by the holding table, and the first main pattern and the second main pattern of the second workpiece are detected based on the coordinate information registered in the positional relationship registration step. The holding table is rotated by a positional relationship (X2'-X1', Y2'-Y1 corresponding to the coordinates (X1', Y1') of the first main pattern and the coordinates (X2', Y2') of the second main pattern. ') The difference between the positional relationship (X2-X1, Y2-Y1) registered in the location registration step The direction of the line dividing the adjusted parallel to the X-axis direction.

In the present invention, it is preferable that the workpiece is in the foregoing A feature region formed in the main pattern is provided in the element, and a region other than the outer peripheral portion of the front surface is sealed by a resin, and the main pattern exposed outside the region sealed by the resin is used for alignment.

In the alignment method of the present invention, since the alignment is performed using the first main pattern and the second main pattern which are respectively separated from each other by the different division planned lines, at least the two main patterns are exposed to the workpiece. On the front side, alignment can be performed with high precision. That is, according to the alignment method provided by the present invention, alignment can be performed with high precision even on an object to be processed having less exposed main patterns.

2‧‧‧Cutting device

4‧‧‧Abutment

4a‧‧‧ Opening

6‧‧‧X-axis mobile station

8‧‧‧Dust-proof drip shield

10‧‧‧ Keeping the table

10a‧‧‧ Keep face

11, 31‧‧‧ processed objects

11a‧‧‧Processed material (first processed object)

11b‧‧‧Processed objects (second workpiece)

12‧‧‧Cutting unit (cutting means)

13‧‧‧ wafer

13a‧‧‧ positive

13b‧‧‧Back

14‧‧‧Support structure

15, 35‧‧‧ dividing line (cutting lane)

15a, 15a-1, 15a-2, 35a‧‧‧1st dividing line

15b, 35b‧‧‧2nd dividing line

16‧‧‧Cutting unit moving mechanism (index feeding method)

17, 37‧‧‧ components

18‧‧‧Y-axis guide

19‧‧‧ main pattern

19a, 19c, 39a, 39c‧‧‧1st main pattern

19b, 19d, 39b, 39d‧‧‧ 2nd main To pattern

20‧‧‧Y-axis moving board

21‧‧‧Resin

22‧‧‧Y-axis screw

23‧‧‧Protection components

24‧‧‧Z-axis guide

26‧‧‧Z-axis moving board

28‧‧‧Z-axis screw

30‧‧‧Z-axis pulse motor

32‧‧‧ camera

34‧‧‧Cutter

36‧‧‧Control devices (control means)

D1, d2‧‧‧ interval

D3‧‧‧ distance

X, Y‧‧ direction

X1, Y1, X2, Y2, X1', Y1', X2', Y2'‧‧‧ coordinates

△X, △Y, △X', △Y'‧‧‧ positional relationship

θ‧‧‧Rotation angle

Fig. 1 is a perspective view schematically showing a configuration example of a cutting device which performs the alignment method of the embodiment.

2(A) is a plan view schematically showing a workpiece in a state of being sucked and held by the holding table, and FIG. 2(B) is a partial cross-sectional side view showing the workpiece in a state in which the holding table is sucked and held. .

Fig. 3(A) is a plan view schematically showing a positional relationship registration step, and Figs. 3(B) and 3(C) are plan views schematically showing an automatic θ matching step.

Fig. 4 is a plan view schematically showing another configuration example of the workpiece to which the alignment method of the embodiment is applied.

Form for implementing the invention

Embodiments of the present invention will be described with reference to the drawings. The alignment method of the present embodiment includes a positional relationship registration step (see FIG. 3(A)) and an automatic θ matching step (see FIGS. 3(B) and 3(C)).

In the positional relationship registration step, the workpieces (first workpieces) to be registered by the holding table are adjusted to an appropriate direction, and then the coordinates of the two main patterns exposed on the front side of the workpiece are respectively Log in as coordinate information. Further, the coordinate positional relationship of the two main patterns is obtained, and registration is performed as the positional relationship information.

In the automatic θ matching step, the two main patterns of the other workpiece (the second workpiece) held by the holding table are detected based on the coordinate information registered in the positional relationship registration step, and the holding table is rotated. The amount of difference between the positional relationship of the coordinates of the two main patterns detected and the positional relationship information registered in the positional relationship registration step. Hereinafter, the alignment method according to the present embodiment will be described in detail.

First, a cutting device that performs the alignment method of the present embodiment will be described. Fig. 1 is a perspective view schematically showing a configuration example of a cutting device which performs the alignment method of the embodiment. As shown in Fig. 1, the cutting device 2 is provided with a base 4 that supports each structure.

On the upper surface side of the base 4, a long rectangular opening 4a is formed in the X-axis direction (front-rear direction, machining feed direction). In the opening 4a, an X-axis moving table 6, an X-axis moving mechanism (machining means) (not shown) for moving the X-axis moving table 6 in the X-axis direction, and an X-axis moving mechanism are provided. Dust and drip-proof cover 8.

The X-axis moving mechanism includes a pair of X-axis guide rails (not shown) that are parallel in the X-axis direction, and the X-axis moving table 6 is slidable on the X-axis guide rails. a nut portion (not shown) is provided on the lower surface side of the X-axis moving table 6, where An X-axis screw (not shown) parallel to the X-axis guide rail is screwed into the nut portion.

An X-axis pulse motor (not shown) is coupled to one end of the X-axis screw. By rotating the X-axis screw with the X-axis pulse motor, the X-axis moving table 6 can be moved in the X-axis direction along the X-axis guide.

On the X-axis moving table 6, a holding table 10 that sucks and holds the workpiece is provided. The holding table 10 is coupled to a rotary drive source (not shown) such as a motor, and is rotated in a form of a rotation axis parallel to the Z-axis direction (vertical direction). Further, the holding table 10 is machined and fed in the X-axis direction by the above-described X-axis moving mechanism.

The front surface (upper surface) of the holding table 10 is a holding surface 10a that sucks and holds the workpiece. The holding surface 10a can be connected to a suction source (not shown) through a flow path (not shown) formed inside the holding table 10.

2(A) is a plan view schematically showing the workpiece in a state in which the holding table 10 is sucked and held, and FIG. 2(B) is a partial cross-sectional view showing the workpiece in a state in which the holding table 10 is sucked and held. Side view.

As shown in FIG. 2(A) and FIG. 2(B), the workpiece 11 is, for example, a WL-CSP (Wafer Level Chip Size Package) substrate, and includes a disk-shaped wafer 13 formed of a material such as tantalum. The front surface 13a of the wafer 13 is divided into a plurality of regions by a predetermined dividing line (cutting track) 15 arranged in a lattice shape, and an element 17 such as an IC is formed in each region.

The division planned line 15 includes a plurality of first division planned lines 15a extending in the first direction, and a plurality of second division planned lines 15b extending in the second direction intersecting the first direction. The interval d1 between the adjacent two first divided planned lines 15a and the interval d2 between the adjacent two second divided planned lines 15b are respectively It is roughly fixed.

A main pattern 19 having a characteristic shape is contained on the element 17. The region 13 (center portion) other than the outer peripheral portion of the front surface 13a of the wafer 13 is sealed by the resin 21, so that the element 17 and the main pattern 19 are not exposed. On the other hand, the outer peripheral portion of the front surface 13a is not covered by the resin 21, and a part of the element 17 and the main pattern 19 is exposed.

As shown in FIG. 2(B), a protective member 23 is attached to the back surface 13b side of the wafer 13. As the protective member 23, for example, a disk-shaped adhesive tape formed of substantially the same outer diameter as the wafer 13, a resin substrate, or the like can be used.

In the cutting device 2, a transfer mechanism (transport means) (not shown) for transporting the workpiece 11 to the holding table 10 is provided at a position close to the opening 4a. The workpiece 11 conveyed by the conveyance mechanism is placed on the holding table 10 so that the front surface 13a side sealed by the resin 21 is exposed upward. The conveying mechanism can place the workpiece 11 on the holding table 10 at a position and direction within a predetermined tolerance range.

On the upper surface of the base 4, a gate-shaped support structure 14 for supporting a cutting unit (cutting means) 12 for cutting the workpiece 11 is disposed to span the opening 4a. A cutting unit moving mechanism (index feeding means) 16 for moving the cutting unit 12 in the Y-axis direction (index feeding direction) and the Z-axis direction (vertical direction) is provided on the upper surface portion before the support structure 14.

The cutting unit moving mechanism 16 includes a pair of Y-axis guide rails 18 that are disposed in front of the support structure 14 and that are parallel to the Y-axis direction. On the Y-axis guide rail 18, the Y-axis moving plate 20 constituting the cutting unit moving mechanism 16 is slidably provided.

A nut portion (not shown) is provided on the back side (rear side) of the Y-axis moving plate 20, and a Y-axis screw 22 parallel to the Y-axis guide rail 18 is screwed into the nut portion. A Y-axis pulse motor (not shown) is coupled to one end portion of the Y-axis screw 22. As long as the Y-axis screw 22 is rotated by the Y-axis pulse motor, the Y-axis moving plate 20 can be moved in the Y-axis direction along the Y-axis guide rail 18.

A pair of Z-axis guide rails 24 parallel to the Z-axis direction are provided on the front surface (front surface) of the Y-axis moving plate 20. The Z-axis moving plate 26 is disposed to be slidable on the Z-axis guide 24.

A nut portion (not shown) is provided on the back side (rear side) of the Z-axis moving plate 26, and a Z-axis screw 28 parallel to the Z-axis guide 24 is screwed into the nut portion. A Z-axis pulse motor 30 is coupled to one end of the Z-axis screw 28. When the Z-axis screw 28 is rotated by the Z-axis pulse motor 30, the Z-axis moving plate 26 can be moved in the Z-axis direction along the Z-axis guide 24.

A cutting unit 12 that cuts the workpiece 11 is provided at a lower portion of the Z-axis moving plate 26. Further, a camera 32 for photographing the upper surface side (the front surface 13a side) of the workpiece 11 is provided at a position adjacent to the cutting unit 12. As long as the cutting unit moving mechanism 16 moves the Y-axis moving plate 20 in the Y-axis direction, the cutting unit 12 and the camera 32 can be indexed and the Z-axis moving plate 26 can be moved in the Z-axis direction. Unit 12 and camera 32 will move up and down.

The cutting unit 12 is provided with an annular cutting blade 34 attached to one end side of a main shaft (not shown) constituting a rotating shaft parallel to the Y-axis direction. A rotary drive source (not shown) such as a motor is coupled to the other end side of the main shaft, and the cutter 34 attached to the main shaft can be rotated.

X-axis moving mechanism, holding table 10, conveying mechanism, cutting unit 12. The components of the cutting unit moving mechanism 16 and the like are connected to a control device (control means) 36, respectively. The control device 36 can control the above-described respective components in a series of steps required for cutting the workpiece 11.

Next, an alignment method of this embodiment performed by the cutting device 2 will be described. In the alignment method of the present embodiment, first, a positional relationship registration step of registering coordinate information and positional relationship information required for alignment on the cutting device 2 is performed. This positional relationship registration step corresponds to the preparation step before the workpiece 11 is processed. Fig. 3(A) is a plan view schematically showing a positional relationship registration step.

In the positional relationship registration step, first, the workpiece (first workpiece) 11a for registration is transported by the transport mechanism, and placed on the holding table 10 such that the resin 21 side (the front surface 13a side) is exposed upward. Next, the negative pressure of the suction source is applied to attract and hold the workpiece 11a on the holding table 10.

After the workpiece 11a is sucked and held on the holding table 10, the upper surface side (the front surface 13a side) of the workpiece 11a is imaged by the camera 32. Then, the holding table 10 is rotated in accordance with the formed captured image, and the direction of the workpiece 11a is adjusted so that, for example, the first dividing line 15a extending in the first direction is parallel to the X-axis direction. Here, the rotation angle (rotation amount) of the holding table 10 is adjusted by the operator.

After the direction of the workpiece 11a has been adjusted, two main patterns 19 corresponding to the two different planned dividing lines are selected on the outer peripheral portion of the workpiece 11a. As shown in Fig. 3(A), in the present embodiment, the first main pattern 19a corresponding to the first dividing line 15a-1 and the second main pattern corresponding to the first dividing line 15a-2 are selected. 19b.

Then, the coordinates (X1, Y1) of the first main pattern 19a and the coordinates (X2, Y2) of the second main pattern 19b are registered as the coordinate information in the control device 36. Further, the positional relationship (ΔX (=X2-X1), ΔY (=Y2-Y1)) of the coordinates (X1, Y2) of the first main pattern 19a and the coordinates (X2, Y2) of the second main pattern 19b is calculated. And is registered as the positional relationship information in the control device 36.

The distance from the first division planned line 15a-1 to the first main pattern 19a and the distance from the first division planned line 15a-2 to the second main pattern 19b are both d3. With the above, the coordinate information and the positional relationship information required for the alignment can be registered on the cutting device 2.

Preferably, in the positional relationship registration step, the two main patterns 19 that are sufficiently separated in the X-axis direction in which the first division planned line 15a extends are selected as the first main pattern 19a and the second main pattern 19b. As described above, by selecting the two main patterns 19 that have been separated, the offset of the workpiece 11 in the rotation direction of the holding table 10 can be made clear, and thus the accuracy of alignment can be easily improved.

After the location relationship registration step is implemented, an automatic θ matching step is implemented. This automatic θ matching step corresponds to a part of the alignment step performed when the workpiece 11 is processed. 3(B) and 3(C) are plan views schematically showing the automatic θ matching step.

In the automatic θ matching step, first, the workpiece (second workpiece) 11b to be processed is conveyed by the transport mechanism, and placed on the holding table 10 such that the resin 21 side (the front surface 13a side) is exposed upward. Next, the negative pressure of the suction source is applied to attract and hold the workpiece 11b on the holding table 10.

After the workpiece 11b is attracted and held on the holding table 10, The camera 32 captures the upper surface side (the front surface 13a side) of the workpiece 11b. Then, based on the formed captured image and the coordinate information of the control device 36, as shown in FIG. 3(B), the first main pattern 19c and the second main pattern 19d exposed on the outer peripheral portion of the workpiece 11b are detected.

Further, since the workpiece 11b is placed on the holding table 10 at a position and direction within a predetermined tolerance range by the transport mechanism, the processed information can be detected based on the coordinate information previously registered in the control device 36. The first main pattern 19c and the second main pattern 19d of the object 11b.

Next, the positional relationship (ΔX'(=X2'-X1') of the coordinates (X1', Y1') of the detected first main pattern 19c and the coordinates (X2', Y2') of the second main pattern 19d is calculated. ), ΔY' (= Y2'-Y1')), and compared with the registered positional relationship information. Thereafter, the control device 36 sets a rotation angle θ corresponding to the difference between the positional relationship (ΔX', ΔY') and the positional relationship (ΔX, ΔY), and holds the holding table 10 as shown in FIG. 3(C). Rotate.

Thereby, the first main pattern 19c moves from the coordinates (X1', Y1') toward the coordinates (X1, Y1), and the second main pattern 19d moves from the coordinates (X2', Y2') toward the coordinates (X2, Y2). . In other words, the direction of the workpiece 11b can be adjusted such that the first division planned line 15a extending in the first direction is parallel to the X-axis direction. Moreover, this automatic θ matching step is automatically implemented in accordance with the control of the control device 36.

As described above, in the alignment method of the present embodiment, the first main patterns 19a and 19c and the second main patterns 19b and 19d which are separated from each other by the two different first predetermined lines 15a are used. Alignment is performed, so that at least two main patterns are exposed on the upper surface of the workpiece 11 The side (front side) allows alignment to be performed with high precision.

Furthermore, the present invention is not limited to the description of the above embodiments, and various modifications can be made. For example, in the above-described embodiment, the first dividing line 15a extending in the first direction is adjusted to be parallel to the X-axis direction. However, the first method may be used to extend the first direction in the first direction. The division planned line 15a is adjusted to be parallel to the Y-axis direction. Needless to say, the second dividing line 15b extending in the second direction may be adjusted to be parallel to the X-axis direction, or the second dividing line 15b extending in the second direction may be adjusted to be parallel to the Y-axis direction.

Further, in the above-described embodiment, the WL-CSP substrate on the front surface 13a side of the wafer 13 is covered with the resin 21 as the workpiece 11, but the alignment method of the present invention is also applied to a more general workpiece. applicable.

Fig. 4 is a plan view schematically showing another configuration example of the workpiece to which the alignment method of the embodiment is applied. As shown in FIG. 4, the workpiece 31 is, for example, a rectangular substrate, and is divided into a plurality of regions by a predetermined dividing line (cutting path) 35 arranged in a lattice shape. In each of the regions, an element 37 such as an IC is formed.

The first main pattern 39a and the second main pattern 39b corresponding to the first division planned line 35a extending in the first direction are formed on the outer peripheral portion of the workpiece 31. Further, a first main pattern 39c and a second main pattern 39d corresponding to the second division planned line 35b extending in the second direction are formed.

When the workpiece 31 is processed, the first main pattern 39a and the second main pattern 39b corresponding to the first division planned line 35a may be used, or the corresponding The first main pattern 39c and the second main pattern 39d of the predetermined line 35b are divided into two, and the alignment is performed in the same manner.

Further, in the alignment method of the present invention, the coordinates of the main pattern 19 may be indicated for each workpiece 11 using a coordinate axis having a different reference point. In other words, it is not necessary to display the reference points of the coordinate axes of the main pattern 19 on the workpiece (the first workpiece) for registration and the workpiece (the second workpiece) to be processed.

In this way, the coordinate axes having different reference points can be used because the positional relationship (ΔX, ΔY) of the two main patterns in each workpiece 11 (ΔX', ΔY') is not based on the reference point of the coordinate axis. However, it is determined only by the relative positions of the two main patterns.

In this case, for example, the coordinates (A, B) of the workpiece (the first workpiece) for registration and the workpiece (the second workpiece) of the workpiece (A, B) are used to hold the table. The rotation axis of 10 is the coordinate axis of the reference point (0.0), which may indicate different positions. In any case, the coordinates of the main pattern 19 of each workpiece 11 may be used as long as the positional relationship (ΔX, ΔY), (ΔX', ΔY') is to be calculated.

In addition, the configuration, the method, and the like of the above-described embodiments can be appropriately modified and implemented without departing from the scope of the invention.

Claims (2)

An alignment method is a first main pattern in which elements are formed in respective regions on the front side which are divided by a plurality of intersecting predetermined lines by using a cutting device, and each of the elements is separated from each other by a different dividing line. An alignment method in which the second main pattern is exposed on the front side, and the first main pattern and the second main pattern are aligned, wherein the cutting device includes a rotatable holding table for holding the workpiece, a cutting means for cutting a workpiece held by the holding table by a cutter, a machining feeding means for machining the holding table in the X-axis direction, and indexing the cutting means in the Y-axis direction The indexing feeding means, the conveying means for conveying the workpiece to the holding table within the allowable error range, and the control means for controlling each component, the alignment method comprising: a positional relationship registration step for maintaining the The first main workpiece is held by the table while the operator holds the holding table by a predetermined amount and adjusts the direction of the dividing line to be parallel to the X-axis direction. The coordinates (X1, Y1) and the coordinates (X2, Y2) of the second main pattern are registered as the coordinate information in the control means, and the coordinates of the first main pattern and the coordinates of the second main pattern are obtained. The positional relationship (X2-X1, Y2-Y1) is registered in the control means; and the automatic θ matching step, after the positional relationship registration step, the second workpiece is transported to the holding table by the transport means to maintain And detecting, on the holding table, the first main pattern and the second main pattern of the second workpiece according to the coordinate information registered in the position registration step, and rotating the holding table corresponding to the first The positional relationship (X2'-X1', Y2'-Y1') of the coordinates (X1', Y1') of the main pattern and the coordinates (X2', Y2') of the second main pattern and the registration step in the positional relationship The amount of difference in the registered positional relationship (X2-X1, Y2-Y1) is adjusted so as to be parallel to the X-axis direction. The alignment method of claim 1, wherein the workpiece has a feature region formed as the main pattern in the element, and a region other than the outer peripheral portion of the front surface is sealed by a resin and used in the resin The main pattern is exposed outside the sealed area for alignment.