JP4440808B2 - Perimeter grinding apparatus and bonded substrate grinding method - Google Patents

Description

  The present invention relates to a peripheral grinding apparatus and a grinding method for grinding a peripheral part of a bonded substrate.

It is known that there is an unbonded portion in the outer peripheral portion 1 to 3 mm of the bonded substrate to which the substrates are bonded, and various techniques have been developed to remove this portion.
For example, the masking tape is adhered except for the outer peripheral portion of the bond wafer of the bonded substrate on the device manufacturing side, and then the unbonded portion at the peripheral portion of the wafer is removed by etching (see Patent Document 1), bond Some wafers are ground to an arbitrary terrace width and the processed part is removed by etching (see Patent Document 2).

  However, with these technologies, the accuracy of the masking tape that guarantees that the tolerance of the terrace processing width is ± 0.5 mm is extremely low, and the maximum processing width after grinding the outer periphery of the bond wafer There is a problem that the difference between the minimum values is large, and thus the tolerance is increased.

JP-A-3-250616 JP 7-45485 A

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an outer peripheral grinding apparatus and a grinding method that improve the tolerance of the terrace processing width in grinding the outer peripheral portion of a bonded substrate.

The present invention is an apparatus for grinding an outer peripheral portion of a bonded substrate obtained by bonding a bond wafer on which a device is manufactured and a base wafer serving as a support substrate, and at least an alignment unit that aligns the bonded substrate; Grinding means for grinding an outer peripheral portion of the bond wafer of the bonded substrate aligned by the alignment device, and the alignment device aligns the bonded substrate with reference to a base wafer. that provides an outer circumference grinding apparatus.

  Thus, an apparatus for grinding an outer peripheral portion of a bonded substrate obtained by bonding a bond wafer on which a device is manufactured and a base wafer serving as a support substrate, and at least means for aligning the bonded substrate, If the alignment means aligns the bonded substrate with reference to a base wafer, the bonding substrate is bonded. Even if the position is shifted in the rotation direction or parallel direction, and the bond wafer and base wafer are offset and bonded, the base wafer is used as the reference, so the bonded substrate is always aligned uniformly without being affected by the shift. As a result, the entire surface can be bonded with a terrace width It can be ground to cause the wafer.

At this time, the alignment means includes a holding base for holding the bonded substrate, and a plurality of pins disposed around the bonded substrate, wherein the holding table and the pin are held. The relative position in the thickness direction of the bonded substrate is adjusted such that the relative position in the thickness direction of the substrate is variable, and the pins are in contact with only the base wafer. those aligned by abutting and even have to desirable.

  As described above, the alignment means includes a holding base for holding the bonded substrate and a plurality of pins arranged around the bonded substrate, and the bonded base substrate and the pins held by the holding table. As long as the relative position in the thickness direction is variable and the pins are aligned by abutting against the base wafer from the periphery, the relative position of the holding table and the pins can be applied to the base wafer of any thickness or diameter. Since the positions of the pins and the base wafer are adjusted, and the pins abut from the outer periphery, the bonded substrate can be aligned with the base wafer as a reference.

Further, the present invention is a method of grinding an outer peripheral portion of a bonded substrate obtained by bonding a bond wafer on which a device is manufactured and a base wafer to be a support substrate, and the bonded substrate is determined based on the base wafer. aligned, that provide bonding method of grinding a substrate is characterized by grinding the outer peripheral portion of the bond wafer of the aligned bonded substrate.

  In this way, the bonded wafer and the base wafer can be used as long as the bonded substrate is ground by aligning the bonded substrate with respect to the base wafer and grinding the outer peripheral portion of the bonded wafer of the aligned bonded substrate. Even if there is a misalignment, the base wafer is the only reference, so alignment can be performed without being affected by the misalignment. It is possible to reduce the width tolerance.

Then, in the alignment, the bonded substrate is held on a holding table, arranged around the bonded substrate, and in a thickness direction of the held bonded substrate so as to be in contact with only the base wafer. position a plurality of pins which are adjusted is not to be of the desired alignment of the bonded substrate by abutting the base wafer from the ambient.

  As described above, in the alignment, the bonded substrate is held on a holding table, and is arranged around the bonded substrate, and a plurality of pins whose positions are adjusted so as to contact only the base wafer, If the bonded substrate is aligned by abutting against the base wafer from the periphery, the bonded wafer can be aligned with respect to the bonded substrate of any thickness and diameter based on the base wafer. It becomes possible to process, and the tolerance of the terrace processing width is reduced.

  An apparatus for grinding an outer peripheral portion of a bonded substrate obtained by bonding a bond wafer on which a device is manufactured and a base wafer serving as a support substrate as in the present invention, and at least alignment means for aligning the bonded substrate And a grinding means for grinding the outer peripheral portion of the bonded wafer of the bonded substrate that has been aligned, and the alignment means is a peripheral grinding device that aligns the bonded substrate with respect to the base wafer. There is a problem with the bonding state of the substrates, and even if the bonded wafer and base wafer are misaligned, the base wafer is used as the reference, so the bonded substrates are always aligned uniformly without being affected by the misalignment. Can tolerate terrace width tolerance on base wafer It can be a small and grinding to.

  In addition, if the bonded substrate is aligned with the base wafer as a reference, and the outer peripheral portion of the bonded wafer of the bonded substrate is ground, the alignment can be performed regardless of the deviation, and therefore the bonded wafer is ground with high accuracy. It is possible to reduce the tolerance of the terrace processing width.

Hereinafter, embodiments of the present invention will be described, but the present invention is not limited thereto.
It is known that there is an unbonded portion in the outer peripheral portion 1 to 3 mm of the bonded substrate, and various techniques have been developed to remove this portion. For example, there is a method in which a bond wafer is subjected to peripheral step grinding to an arbitrary terrace width, and a processed portion is removed by etching.
When the bonded substrate is manufactured in this way, for example, grinding is performed on the bond wafer in order to remove the unbonded portion on the outer peripheral portion.
However, in the terrace processing width of the bonded substrate after grinding, there is a large difference depending on the position, and there is a problem that it is difficult to reduce the tolerance.

The present inventors have a problem in the bonding state of the substrates to be processed as a cause of the large tolerance of the terrace width, and when the bond wafer and the base wafer are bonded to each other in a rotational direction or a parallel direction, In the outer peripheral grinding apparatus, since the substrate is aligned with respect to the entire substrate, it has been found that the bonding deviation affects the tolerance of the terrace processing width.
Accordingly, the present inventors have completed a grinding apparatus and a grinding method for aligning a bonded substrate on the basis of only the base wafer, not the entire bonded substrate.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, an example of the peripheral grinding apparatus of the present invention will be described with reference to FIG.
This outer peripheral grinding apparatus 1 includes a wafer loading / unloading robot 2, and a wafer carrier 3 is disposed around the periphery grinding apparatus 1. A temporary table 4 is installed on the wafer carrier 3 side, and a transfer robot 5, an alignment unit 6, a chuck table 7, and a grinding unit 8 are disposed at the back of the outer peripheral grinding apparatus 1.

The bonded substrate W set in the wafer carrier 3 of the peripheral grinding device 1 is taken out from the wafer carrier 3 by the loading / unloading robot 2 and placed on the temporary placement table 4. Next, the bonded substrate W is carried by the transfer robot 5 and heads toward the alignment means 6.
The bonded substrate W carried to the alignment means 6 is held on the holding table 12, and is first pre-aligned (coarse alignment) by optical detection of notches and orientation flats. Thereafter, the alignment means 6 performs alignment with the base wafer of the bonded substrate W as a reference.
After being aligned, the bonded substrate W is transported and fixed to the chuck table 7 by the transport robot 5, and the outer peripheral portion thereof is ground by the grinding wheel 9 of the grinding means 8.

  As described above, in the peripheral grinding apparatus 1 of the present invention, alignment is performed by the alignment means 6 with reference to the base wafer of the bonded substrate W. Therefore, in the bonded substrate W, the bonded state of the base wafer and the bond wafer is rotated. Even if it is shifted in the direction or parallel direction, the bonded substrate W can be always aligned uniformly without being affected by the shift.

  Here, details of the alignment means 6 of the present invention will be described with reference to FIGS. 2A and 2B are a plan view and a cross-sectional view, respectively, seen from above during alignment of the bonded substrate W. On the other hand, FIGS. 2C and 2D are respectively a cross-sectional view during alignment of the bonded substrate W by a conventional peripheral grinding apparatus and a plan view seen from above. As shown in (B) and (C), the bonded wafers are bonded with a slight shift in the parallel direction, or bonded in the rotational direction as shown in (D).

  As shown in FIGS. 2A and 2B, the bonded substrate W formed by bonding the bond wafer 10 on the device manufacturing side and the base wafer 11 that is the support substrate is held on the holding table 12 during alignment. In addition, a plurality of pins 13 (four in the figure) are arranged around the periphery. Instead of the pins 13, for example, a clamp that holds a wafer with a mechanical fork used for handling the wafer may be used, or alignment may be performed in a non-contact manner using an optical sensor or the like.

The relative positions of the holder 12 and the pin 13 is the thickness direction T ₂ of the bonded substrate W is variable, by adjusting the relative position of the holder 12 and the pin 13 therefor, a bonded substrate W on the holding table 12 The base wafer 11 and the pins 13 can be aligned with each other. In this way, when the pin 13 is adjusted to a position where only the base wafer 11 is brought into contact, the pin 13 is brought into contact with only the base wafer 11 from the periphery of the bonded substrate W to align the bonded substrate W. .

Here, as a means for adjusting the relative position of the holding table 12 and the pin 13, for example, a method of changing the height of the holding table 12 and / or the pin 13 can be mentioned. When the thickness of the bonded substrate W is changed, the holding table 12 and / or the pin 13 having a height corresponding to the thickness is prepared, and the holding table 12 and the pin 13 are moved to a desired relative position by re-setting to the outer peripheral grinding apparatus 1. Can be adjusted to the position. Simply, the length of the pin 13 and the thickness of the holding table 12 may be changed. Also, attached to the moving mechanism to the holding base 12 and / or pin 13, supporting table 12 in the thickness direction T ₂ of the substrate W bonded, either pin 13 or by translating both, mutual relative position May be adjusted.
As described above, the means for adjusting the relative position between the holding table 12 and the pin 13 is not particularly limited as long as it can adjust the position so that the pin 13 can be brought into contact with the base wafer 11 and aligned.

Further, after adjusting the relative positions of the holding table 12 and the pins 13 in the thickness direction T ₂ of the bonded substrate W on the holding table 12, the pins 13 are brought into contact with each other from the periphery of the base wafer 11 to align the bonded substrate W. . Thus, by arranging the pin 13 in the periphery of the substrate W, when aligned so as to sandwich the bonded substrate W from the periphery in the surface direction T ₁ parallel to the substrate W, they change the diameter of the bonded substrate W Since it can respond without a problem, it is possible to handle the bonded substrates W having various sizes of diameters.

  If such an alignment means 6 is used, the relative positions of the holding table 12 and the pins 13 can be changed even if the thickness or diameter of the bonded substrate W changes, so that the positions of the pins 13 and the base wafer 11 are adjusted. The bonded substrate W can be aligned with the base wafer 11 as a reference by bringing the pins 13 into contact with only the base wafer 11. Further, since the pins 13 are in contact with only the base wafer 11, even if the bonded substrate W is shifted and bonded in the parallel direction as shown in FIG. Aligned.

  On the other hand, FIG. 2C shows the alignment of the substrate W in the conventional apparatus for comparison. In the conventional apparatus, alignment is performed using the entire bonded substrate W as a reference, and the pin 13 ′ is in contact with not only the base wafer 11 but also the bond wafer 10. Therefore, when the bonding of the bond wafer 10 and the base wafer 11 on the bonded substrate W is shifted in the parallel direction, the shift affects the alignment and does not match the alignment based on the base wafer 11. . If the outer peripheral portion of the bonded substrate W is ground while being affected by the deviation, the difference due to the position of the terrace processing width increases, and the tolerance increases.

  FIG. 2D shows a case where the base wafer 11 of the bonded substrate W and the bond wafer 10 are bonded to each other while being displaced in the rotational direction. In this case as well, if the alignment is performed using the entire bonded substrate as a reference, the orientation flat position cannot be accurately captured, and an error occurs when the outer peripheral portion is ground.

  Next, for example, when the bonding substrate W in which the bonding of the bond wafer 10 and the base wafer 11 is shifted in the parallel direction is an object, and the holding table 12 and the pins 13 are used as an alignment method based on the base wafer 11 As an example, the effectiveness of the method for grinding a bonded substrate W according to the present invention will be described using the schematic explanatory diagram of the grinding method according to the present invention in FIG.

In the grinding method of the present invention, the bonded substrate W is aligned with reference to the base wafer 11 (see FIG. 3A). For this reason, even if the bonding of the bond wafer 10 and the base wafer 11 is deviated in the parallel direction, since the grinding is performed only on the base wafer 11, there is no influence due to the misalignment of the bonding, and the terrace after the grinding There is no difference between the processing widths L ₁ and L ₂ (see FIG. 3B). Therefore, the processing accuracy is improved and the tolerance of the terrace processing width is reduced.

By such a grinding method, even if there is a deviation in bonding of the bond wafer 10 and the base wafer 11, the bond wafer 10 can be ground without being affected by the deviation. Therefore, it is possible to suppress the difference between the maximum and minimum terrace processing widths, obtain a processed wafer with high accuracy, and reduce the tolerance.
In addition, by adjusting the relative position of the holding base 12 and the pin 13 in the thickness direction of the bonded substrate W using, for example, the holding table 12 and the pin 13 at the time of alignment, and from the periphery of the bonded substrate W By bringing the pins 13 into contact with the base wafer 11, it is possible to align the bonded wafer W of any thickness and diameter with the base wafer 11 as a reference. Can be ground.

On the other hand, FIG. 4 shows a schematic explanatory diagram of grinding by the conventional method.
In the conventional method, the bonded substrate W is aligned based on the entire bonded substrate W, and then the outer peripheral portion of the bond wafer 10 is ground. For this reason, the center axes of the bond wafer 10 and the base wafer 11 after grinding are not aligned due to the influence of the shift in the parallel direction when the bond wafer 10 and the base wafer 11 are bonded, and the terrace processing widths L ₃ and L ₄ There is a difference. As described above, in the conventional method, the alignment is affected by the misalignment of the bonding, so that the grinding accuracy is affected, and the tolerance of the terrace processing width becomes large.

Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited thereto.
Example 1
Fifty bonded substrates made of a silicon single crystal wafer having a diameter of 6 inches (150 mm) and a base wafer and a bond wafer each having a thickness of 625 μm were prepared.
Using the peripheral grinding apparatus of the present invention, alignment was performed with the base wafer as a reference, and the peripheral portions of these bonded substrates were ground with an aim of a width of 3 mm. As grinding conditions, a # 800 diamond grindstone was used, and they were rotated in reverse directions at a peripheral speed of 1600 m / min of the grindstone and a peripheral speed of 300 mm / min of the bonded substrate. The grinding speed was 0.6 mm / min, and grinding was performed until the thickness of the bond wafer reached 100 μm. After grinding, alkali etching using NaOH was performed, and then the terrace processing width was measured at four points.

FIG. 5 shows the measurement results of Example 1.
From FIG. 5, it can be confirmed that the frequency of the processed substrate is concentrated in the vicinity of the processed width of 3.0 mm and is as intended. Further, it can be seen that not only the number of processed substrates protrudes in the vicinity of 3.0 mm, but also the difference between the maximum and minimum processing widths is small and variation is suppressed (average 2.9839 mm, σ = 0.030, R = max−min = 0.163).
From this, it turns out that the outer peripheral part of the bonded substrate was able to be accurately ground by the present invention with respect to the target processing width. For this reason, the tolerance can be reduced, and in Example 1, it was ± 0.5 mm in the past, but it was improved to ± 0.2 mm.

(Comparative Example 1)
210 bonded substrates produced in the same manner as those used in Example 1 were prepared.
Using a conventional peripheral grinding apparatus, alignment was performed with the entire bonded substrate as a reference, and the peripheral portions of these bonded substrates were ground with a processing width of 3.0 mm as in Example 1.
Other grinding conditions are the same as in the first embodiment. After grinding, alkali etching using NaOH was performed, and then the terrace processing width was measured at four points.

FIG. 6 shows the result of Comparative Example 1.
From FIG. 6, it can be confirmed that the difference between the maximum value and the minimum value of the processing width is larger than that of Example 1 and the variation is large (average 3.0932 mm, σ = 0.107, R = 0.552). As in Example 1, it was not within the range of ± 0.2 mm. In such a case, even if the number of processed substrates tends to concentrate in the vicinity of the target processing width, the tolerance increases due to the wide distribution range. In addition, even if the distribution range is within tolerances, if the distribution range is wide and close to the limits of the standard, it is necessary to inspect all of them, causing problems in terms of cost, time, etc. End up.

  As described above, the outer periphery grinding apparatus and the grinding method of the present invention enables alignment with the base wafer of the bonded substrate as a reference, thereby enabling the outer periphery of the bond wafer to be ground with high accuracy, and the tolerance of the terrace processing width. Can be reduced and improved.

  In addition, this invention is not limited to the said form. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

It is the schematic of the outer periphery grinding apparatus of this invention. (A) It is explanatory drawing (plan view) which shows the mode of alignment of the bonding board | substrate by the outer periphery grinding apparatus of this invention. (B) It is explanatory drawing (cross-sectional view) which shows the mode of alignment of the bonding board | substrate by the outer periphery grinding apparatus of this invention. (C) It is explanatory drawing which shows the mode of alignment of the bonded substrate board by the conventional outer periphery grinding apparatus. (D) It is the figure which showed the mode of the alignment in case the wafer was bonded by shifting | deviating to the rotation direction. It is a schematic explanatory drawing of the grinding method of the bonded substrate board of this invention. It is a schematic explanatory drawing of the grinding method of the bonding substrate of the conventional method. It is a measurement result of Example 1. It is a measurement result of comparative example 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Perimeter grinding apparatus of this invention, 2 ... Wafer entrance / exit robot,
3 ... Wafer carrier, 4 ... Temporary table, 5 ... Transfer robot,
6 ... Alignment means, 7 ... Chuck table, 8 ... Grinding means,
9 ... Grinding wheel, 10 ... Bond wafer,
11 ... Base wafer, 12 ... Holding stand, 13, 13 '... Pin,
T ₁ ... direction parallel to the surface of the bonded substrate,
T ₂ ... Thickness direction of bonded substrate L ₁ , L ₂ , L ₃ , L ₄ ... Terrace processing width, W ... Bonded substrate.

Claims (2)

An apparatus for grinding an outer peripheral portion of a bonded substrate obtained by bonding a bond wafer on which a device is manufactured and a base wafer to be a supporting substrate,
At least alignment means for aligning the bonded substrate; and grinding means for grinding an outer peripheral portion of a bond wafer of the bonded substrate aligned by the alignment device, wherein the alignment device is based on the base wafer. all SANYO to align the bonded substrate,
The alignment means includes a holding table for holding the bonded substrate, and a plurality of pins disposed around the bonded substrate, wherein the holding table and the pin are held by a thickness of the bonded substrate. The relative position in the direction is variable, and the relative position in the thickness direction of the bonded substrate is adjusted so that the pin contacts only the base wafer, and the pin contacts the base wafer from the periphery. An outer peripheral grinding device characterized by being aligned by the above . A method of grinding an outer peripheral portion of a bonded substrate obtained by bonding a bond wafer on which a device is manufactured and a base wafer to be a supporting substrate,
When aligning the bonded substrate with the base wafer as a reference , the bonded substrate is held on a holding table, arranged around the bonded substrate, and held so as to contact only the base wafer. A plurality of pins adjusted in position with respect to the thickness direction of the bonded substrate are aligned with the bonded substrate by contacting the base wafer from the periphery,
A method for grinding a bonded substrate, comprising grinding an outer peripheral portion of the bond wafer of the aligned bonded substrate.

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