JP7526611B2 - Processing system and processing method - Google Patents

Description

This disclosure relates to a processing system and a processing method.

Patent Document 1 discloses a dressing board for dressing the grinding stones of a grinding wheel. The dressing board is composed of a first layer that is adhered to a support plate and a second layer that is ground with the grinding stone. The first and second layers have different hues, and the first layer becomes visible as the second layer wears away, allowing the limit of use to be identified by color.

JP 2014-217935 A

The technology disclosed herein properly processes grinding tools.

One aspect of the present disclosure is a processing system for a processed object, comprising: a holding section for holding the processed object; a grinding section including a grinding tool for grinding the processed object held in the holding section and a moving mechanism for moving the grinding tool relative to the processed object; a measuring section for measuring a thickness of the processed object; and a display section for displaying a grinding status of the processed object, wherein the processed object is a dressing board, and the display section displays the amount of movement of the grinding tool relative to the processed object and the difference between the thickness of the processed object before grinding and the thickness of the processed object after grinding , and judges whether the grinding of the processed object is normal or abnormal based on the difference or the dressing amount of the grinding tool obtained by subtracting the difference from the amount of movement, and the threshold value of the difference used in the judgment is set according to the combination of the processed object and the grinding tool.

According to this disclosure, grinding tools can be processed appropriately.

1 is a plan view showing an outline of a configuration of a processing device according to an embodiment of the present invention; FIG. 2 is a side view showing an outline of the configuration of each grinding unit and a chuck. FIG. 2 is a plan view showing an outline of the configuration of a dress board. FIG. 2 is a side view showing an outline of the configuration of the dress board. FIG. 11 is an explanatory diagram showing a state in which a rough grinding wheel is dressed. FIG. 11 is an explanatory diagram showing a state in which the rough grinding wheel is dressed. FIG. 11 is an explanatory diagram showing how the thickness of the dress board is measured by the measuring unit. FIG. 2 is an explanatory diagram showing a display example of a display panel according to the present embodiment. FIG. 2 is a flow chart showing main steps of a dressing treatment for a rough grinding wheel. 1 is an explanatory diagram showing the relationship between the dressing amount D of a rough grinding wheel and the thickness difference T of a dressing board in dressing of the rough grinding wheel; FIG. FIG. 11 is an explanatory diagram showing a display example of a display panel according to another embodiment.

In recent years, in the manufacturing process of semiconductor devices, a semiconductor substrate (hereinafter referred to as a "wafer") having a number of electronic circuits and other devices formed on its surface is thinned by grinding the back surface of the wafer. Grinding of the back surface of the wafer is performed, for example, by holding the surface of the wafer opposite the surface to be ground with a holding part and rotating the holding part while bringing a grinding wheel of the grinding part into contact with the back surface of the wafer.

When grinding a wafer, the grinding wheel becomes dull and clogged as the grinding progresses. For this reason, in order to maintain grinding accuracy, it is necessary to dress the grinding wheel and adjust the surface condition of the grinding wheel.

Patent Document 1 discloses a dressing board used for dressing grinding wheels. This dressing board is composed of a first layer and a second layer, and the first layer becomes visible as the second layer wears away, thereby identifying the limit of use by color, and thus identifying the limit of use of the dressing board (dressing tool).

Here, in order to properly dress the grinding wheel, it is necessary to properly grasp the state of the grinding wheel after the dressing. However, while measures have been taken to grasp the usage limit of the dressing board, for example as disclosed in Patent Document 1, the state of the grinding wheel has not been grasped. In other words, it is not possible to determine whether or not the dressing has been performed normally. Therefore, there is room for improvement in conventional dressing of grinding wheels.

The technology disclosed herein appropriately processes grinding tools. Below, the processing device as a processing system and the processing method according to this embodiment will be described with reference to the drawings. Note that in this specification and the drawings, elements having substantially the same functional configurations are given the same reference numerals to avoid redundant description.

In the processing apparatus 1 according to this embodiment, the wafer W is thinned. The wafer W is a semiconductor wafer such as a silicon wafer or a compound semiconductor wafer, and a device is formed on the front surface. In the processing apparatus 1, a process such as grinding is performed on the rear surface of the wafer W, thereby thinning the wafer W. In addition, the processing apparatus 1 dresses the grinding wheel.

As shown in FIG. 1, the processing device 1 has a configuration in which a loading/unloading station 2 and a processing station 3 are integrally connected. In the loading/unloading station 2, for example, a cassette C capable of housing multiple wafers W is loaded and unloaded between the loading/unloading station 2 and the outside. The processing station 3 is equipped with various processing devices that perform the desired processing on the wafers W.

The loading/unloading station 2 is provided with a cassette mounting table 10. In addition, a wafer transport area 20 is provided adjacent to the cassette mounting table 10 on the positive Y-axis side of the cassette mounting table 10. The wafer transport area 20 is provided with a wafer transport device 22 that is movable on a transport path 21 that extends in the X-axis direction.

The wafer transport device 22 has a transport fork 23 that holds and transports the wafer W. The transport fork 23 is configured to be movable horizontally, vertically, around a horizontal axis, and around a vertical axis. The wafer transport device 22 is configured to be able to transport the wafer W to the cassette C on the cassette mounting table 10, the alignment section 50, and the first cleaning section 60.

In the processing station 3, processing such as grinding and cleaning is performed on the wafer W. The processing station 3 has a transfer section 30 that transfers the wafer W, a grinding section 40 that performs a grinding process on the wafer W, an alignment section 50 that adjusts the horizontal orientation of the wafer W before the grinding process, a first cleaning section 60 that cleans the wafer W after the grinding process, and a second cleaning section 70 that cleans the wafer W after the grinding process.

The transfer unit 30 is an articulated robot equipped with multiple, for example, three, arms 31. Each of the three arms 31 is configured to be freely rotatable. A transfer pad 32 that suctions and holds the wafer W is attached to the arm 31 at the tip. The arm 31 at the base end is attached to a lifting mechanism 33 that raises and lowers the arm 31 in the vertical direction. The transfer unit 30 is configured to be able to transport the wafer W to the transfer position A0 of the grinding unit 40, the alignment unit 50, the first cleaning unit 60, and the second cleaning unit 70.

The grinding section 40 is provided with a rotating table 41. Four chucks 42 are provided on the rotating table 41 as holding sections for suction-holding the wafer W. For example, a porous chuck is used as the chuck 42, and it suction-holds the surface of the wafer W. The surface of the chuck 42, i.e., the holding surface of the wafer W, has a convex shape in which the center protrudes compared to the ends when viewed from the side. Note that because this protrusion in the center is very small, the convex shape of the chuck 42 is omitted in the illustrations in the following description.

2, the chuck 42 is held by the chuck base 43. The chuck base 43 is provided with an inclination adjustment unit 44 that adjusts the relative inclination between each grinding unit (rough grinding unit 80, medium grinding unit 90, and finish grinding unit 100) and the chuck 42. The inclination adjustment unit 44 has a fixed shaft 45 provided on the underside of the chuck base 43 and multiple, for example, two, lifting shafts 46. Each lifting shaft 46 is configured to be freely expandable and contractible, and raises and lowers the chuck base 43. This inclination adjustment unit 44 can tilt the chuck 42 and the chuck base 43 by raising and lowering the other end in the vertical direction by the lifting shaft 46, with one end of the outer periphery of the chuck base 43 (the position corresponding to the fixed shaft 45) as the base point. This allows the relative inclination between each grinding unit 80, 90, 100 at the processing positions A1 to A3 and the surface of the chuck 42 to be adjusted.

The configuration of the tilt adjustment unit 44 is not limited to this, and can be selected arbitrarily as long as it is possible to adjust the relative angle (parallelism) of the surface (holding surface) of the chuck 42 with respect to each grinding portion (grinding surface).

The four chucks 42 can be moved to the transfer position A0 and the processing positions A1 to A3 by the rotation of the rotary table 41. In addition, each of the four chucks 42 is configured to be rotatable around a vertical axis by a rotation mechanism (not shown).

At the transfer position A0, the transfer unit 30 transfers the wafer W. At the processing position A1, the rough grinding unit 80 is located and performs rough grinding of the wafer W. At the processing position A2, the medium grinding unit 90 is located and performs medium grinding of the wafer W. At the processing position A3, the finish grinding unit 100 is located and performs finish grinding of the wafer W.

As shown in FIG. 2, the rough grinding unit 80 has a rough grinding wheel 81 with a rough grinding stone on the underside as an annular grinding tool, a mount 82 that supports the rough grinding wheel 81, a spindle 83 that rotates the rough grinding wheel 81 via the mount 82, and a drive unit 84 that incorporates, for example, a motor (not shown). The rough grinding unit 80 is also configured to be movable in the vertical direction along the support 85 shown in FIG. 1. In this embodiment, the drive unit 84 and the support 85 constitute the movement mechanism of the present disclosure.

The medium grinding unit 90 has a similar configuration to the rough grinding unit 80. That is, the medium grinding unit 90 has a medium grinding wheel 91 equipped with a medium grinding stone as an annular grinding tool, a mount 92, a spindle 93, a drive unit 94, and a support 95. The grain size of the abrasive grains of the medium grinding stone is smaller than the grain size of the abrasive grains of the rough grinding stone.

The finish grinding section 100 has a similar configuration to the rough grinding section 80 and the medium grinding section 90. That is, the finish grinding section 100 has a finish grinding wheel 101 equipped with a finish grinding stone as an annular grinding tool, a mount 102, a spindle 103, a drive section 104, and a support 105. The grain size of the abrasive grains of the finish grinding stone is smaller than the grain size of the abrasive grains of the medium grinding stone.

In addition, at the transfer position A0 and processing positions A1 to A3 of the grinding unit 40, a measuring unit 110 is provided for measuring the thickness of the wafer W or the thickness of the dressing grindstone 141 of the dress board 140, which will be described later. For example, a contact-type thickness measuring mechanism is used for the measuring unit 110. The configuration of the measuring unit 110 will be described later.

The above processing device 1 is provided with a display panel 120 as a display unit. The display panel 120 is, for example, a monitor or a touch panel, and may be attached directly to the processing device 1 or may be capable of being viewed remotely. The display panel 120 displays the status of wafer processing, the status of dressing of the grinding wheel, etc. The configuration of the display panel 120 will be described later.

The processing apparatus 1 is also provided with a control unit 130. The control unit 130 is, for example, a computer equipped with a CPU, memory, etc., and has a program storage unit (not shown). The program storage unit stores a program for controlling the processing of the wafer W in the processing apparatus 1. The program storage unit also stores a program for controlling the dressing, which will be described later. The above program may be recorded in a computer-readable storage medium H and installed in the control unit 130 from the storage medium H.

When grinding is performed on multiple wafers W, the grinding wheels (rough grinding wheel, medium grinding wheel, and finish grinding wheel) become dull or clogged as the grinding process progresses. For this reason, in order to maintain grinding accuracy, it is necessary to dress the grinding wheels and adjust the surface condition of the grinding wheels. The dressing of the grinding wheels performed by the processing device 1 is described below.

Dressing of the grinding wheel is performed using a dressing board 140 as the object to be processed. As shown in Figures 3 and 4, the dressing board 140 has a disk-shaped dressing wheel 141 and a disk-shaped base 142 that is provided on the underside of the dressing wheel 141 and supports the dressing wheel 141.

The dressing wheel 141 is used according to the combination with each grinding wheel (rough grinding wheel, medium grinding wheel, and finish grinding wheel). In other words, the grain size of the dressing wheel 141 is set according to the grain size of each grinding wheel. Therefore, multiple dressing wheels 141 (dressing boards 140) may be prepared for each of the rough grinding wheel, medium grinding wheel, and finish grinding wheel.

When the rough grinding wheel is dressed using the dressing board 140, the dressing board 140 is held by the chuck 42 as shown in FIG. 5. Next, the rough grinding wheel 81 (rough grinding wheel) is moved vertically downward relative to the dressing board 140, and the rough grinding wheel is brought into contact with the dressing board 140. Then, the rough grinding wheel and the dressing board 140 are rotated, and the rough grinding wheel is further moved vertically downward. Then, as shown in FIG. 6, the surface of the rough grinding wheel of the rough grinding wheel 81 is ground and dressed. That is, while the surface of the rough grinding wheel is rough before dressing as shown in FIG. 6(a), the surface condition of the rough grinding wheel after dressing is adjusted to a state in which the next rough grinding of the wafer W is appropriately performed as shown in FIG. 6(b).

In the following explanation, the vertical downward movement of the rough grinding wheel from when it contacts the dressing board 140 until dressing is completed is referred to as the feed amount. The amount by which the rough grinding wheel is ground is referred to as the dressing amount D. Note that the dressing of the medium grinding wheel and the finish grinding wheel are each performed in the same manner as the dressing of the rough grinding wheel.

As described above, each grinding wheel is dressed using the dressing board 140. Furthermore, in this embodiment, when dressing each grinding wheel, it is determined whether the dressing was normal or abnormal based on the dressing board 140 before and after dressing. In the following description, each grinding wheel may be collectively referred to simply as a grinding wheel.

The thickness of the dressing grindstone 141 on the dressing board 140 is measured using the measuring unit 110 described above. As shown in FIG. 7, the measuring unit 110 has a height gauge 111 on the base side, a height gauge 112 on the dressing grindstone side, and a calculation unit 113. The height gauge 111 has a probe 114, and the tip of the probe 114 contacts the upper surface of the base 142 to measure the height position of the upper surface. The height gauge 112 has a probe 115, and the tip of the probe 115 contacts the upper surface of the dressing grindstone 141 to measure the height position of the upper surface. The calculation unit 113 calculates the thickness of the dressing grindstone 141 by subtracting the measurement value of the height gauge 111 from the measurement value of the height gauge 112. In the following description, the thickness of the dressing grindstone 141 may be referred to as the thickness of the dressing board 140. In addition, the tip of the probe 114 may contact the upper surface (frame) of the chuck 42, and the measuring unit 110 may measure the thickness of the dress board 140.

As shown in FIG. 8, the display panel 120 displays the status of the dressing of the grinding wheel. Specifically, the display panel 120 displays the feed amount of the grinding wheel for each grinding wheel 81, 91, and 101, and the thickness of the dress board 140.

As described above, the feed amount of the grinding wheel is the amount of movement of the grinding wheel from when the grinding wheel contacts the dressing board 140 until dressing is completed. The feed amount is input by the operator, for example, as one of the dressing processing recipes. Note that the input screen for this processing recipe is displayed on the display panel 120 as a separate screen from the screen shown in FIG. 8.

The thickness of the dressing board 140 displayed is the thickness of the dressing board 140 before dressing, the thickness of the dressing board 140 after dressing, and the difference between these. The thicknesses of the dressing board 140 before and after dressing are each measured by the measuring unit 110. The measurement results of the thickness of the dressing board 140 by the measuring unit 110 are output to the control unit 130, which calculates the difference in thickness of the dressing board 140 before and after dressing. In other words, this difference is the amount of wear of the dressing board 140, and in the following explanation, it is referred to as the thickness difference of the dressing board 140.

A confirmation button is also displayed on the display panel 120. Once the operator has confirmed the status of the dressing of the grinding wheel, they can press the confirmation button to move to the next screen.

Next, a series of dressing processes using the dressing board 140 performed by the processing device 1 will be described. In the following explanation, the case of dressing a rough grinding wheel will be described, but the same applies to dressing a medium grinding wheel and a finish grinding wheel.

First, at the processing position A1, the dress board 140 is held by the chuck 42 (step S1 in FIG. 9). The dress board 140 may be automatically transported to the chuck 42 or may be manually placed thereon. When the dress board 140 is automatically transported to the chuck 42, for example, the dress board 140 may be transported from outside the processing device 1 to the loading/unloading station 2 and then transferred to the chuck 42 via the wafer transport device 22 and the transport section 30. Alternatively, the dress board 140 may be stored inside the processing device 1 and then transferred to the chuck 42.

Next, as shown in FIG. 7, the thickness of the dress board 140 before dressing is measured by the measuring unit 110 (step S2 in FIG. 9). The measurement result of the thickness of the dress board 140 is displayed on the display panel 120 as shown in FIG. 8. In this embodiment, the thickness of the dress board 140 before dressing is 3000 μm.

Next, the rough grinding wheel 81 (rough grinding stone) is moved vertically downward relative to the dress board 140, and the rough grinding stone is brought into contact with the dress board 140. Next, as shown in FIG. 5, the rough grinding stone and the dress board 140 are rotated, and the rough grinding stone is further moved vertically downward. Then, as shown in FIG. 6, the surface of the rough grinding stone of the rough grinding wheel 81 is ground and dressed (step S3 in FIG. 9).

In step S3, the feed rate of the rough grinding wheel is input by the operator as one of the dressing process recipes as described above. In this embodiment, the feed rate of the rough grinding wheel is 100 μm, as shown in FIG. 8.

In step S3, the start position of dressing, i.e., the position where the rough grinding wheel contacts the dress board 140, is set based on the thickness of the dress board 140 measured in step S2. Then, in step S3, the rough grinding wheel moves vertically downward by an additional 100 μm, and the rough grinding wheel is dressed.

Next, as shown in FIG. 7, the thickness of the dress board 140 after dressing is measured by the measuring unit 110 (step S4 in FIG. 9). The measurement result of the thickness of the dress board 140 is displayed on the display panel 120 as shown in FIG. 8. In this embodiment, the thickness of the dress board 140 after dressing is 2950 μm.

Next, the control unit 130 calculates the difference between the thickness of the dress board 140 before dressing measured in step S2 and the thickness of the dress board 140 before dressing measured in step S4 (step S5 in FIG. 9). That is, in step S5, the thickness difference, which is the amount of wear of the dress board 140, is calculated as described above. The thickness difference of the dress board 140 is displayed on the display panel 120 as shown in FIG. 8. In this embodiment, the thickness difference of the dress board 140 is 50 μm.

Next, the normality or abnormality of the dressing is determined based on the feed amount of the rough grinding wheel (100 μm) and the thickness difference of the dress board 140 (50 μm) (step S6 in FIG. 9).

For example, when dressing is performed normally, the set value of the thickness difference of the dress board 140 is 50 μm, and the set value of the dressing amount of the rough grinding wheel is 50 μm. In this embodiment, the ratio between the set value of the thickness difference of the dress board 140 and the set value of the dressing amount of the rough grinding wheel is 50:50, but is not limited to this. The ratio is set according to the combination of the dress board 140 and the rough grinding wheel.

The threshold value of the thickness difference of the dress board 140 when determining whether the dressing is normal or abnormal is within a predetermined tolerance range from the above-mentioned set value of 50 μm. For example, if the tolerance range is ±10 μm, the threshold value of the thickness difference T of the dress board 140 shown in FIG. 10 is 40 μm to 60 μm.

For example, if the thickness difference T of the dress board 140 is between 40 μm and 60 μm, it is determined that the dressing was performed normally. In other words, the dressing amount D of the rough grinding wheel is between 60 μm and 40 μm, and it is determined that the surface of the rough grinding wheel has been properly ground. In this embodiment, as shown in FIG. 8, the thickness difference of the dress board 140 is 50 μm, so it is determined that the dressing was normal.

On the other hand, if the thickness difference T of the dress board 140 is less than 40 μm or more than 60 μm, it is determined that the dressing was abnormal. In other words, it is determined that the dressing amount D of the rough grinding wheel is more than 60 μm or less than 40 μm, and the surface of the rough grinding wheel is not ground properly.

This completes the dressing process for the rough grinding wheel.

According to the above embodiment, it is possible to determine whether the dressing is normal or abnormal based on the feed amount of the grinding wheel and the thickness difference of the dress board 140. Therefore, if the dressing is determined to be normal, the surface condition of the grinding wheel is appropriately adjusted, so that the next grinding of the wafer W can be performed appropriately.

In addition, in this embodiment, the thickness difference of the dressing board 140 is automatically calculated, and the normality or abnormality of the dressing is also automatically determined. Therefore, the normality or abnormality of the dressing can be accurately confirmed. It is also possible to reduce the effort required of the operator to determine whether the dressing is normal or abnormal.

In addition, in this embodiment, the feed amount of the grinding wheel and the thickness difference of the dressing board 140 are displayed on the display panel 120, allowing the operator to visually check whether the dressing is normal or abnormal.

In the above embodiment, the display panel 120 displays the feed amount of the grinding wheel and the thickness of the dressing board 140, but the display items are not limited to this. For example, as shown in FIG. 11, the dressing amount of the grinding wheel, which is calculated by subtracting the thickness difference of the dressing board 140 from the feed amount of the grinding wheel, may be displayed. In such a case, the operator can directly check whether the dressing is normal or abnormal.

In the above embodiment, a contact-type thickness measurement mechanism is used for the measurement unit 110 that measures the thickness of the dressing grindstone 141 of the dressing board 140, but a non-contact type thickness measurement mechanism may also be used. For example, a light transmission type sensor or a reflection type sensor is used for the non-contact type thickness measurement mechanism.

In addition, in the above embodiment, the measuring unit 110 measured the thickness of the dress board 140, but it may also measure the thickness of each grinding wheel.

In addition, in the above embodiment, the grinding unit 40 has been described as having a three-axis configuration (rough grinding unit 80, medium grinding unit 90, and finish grinding unit 100), but the configuration of the grinding unit 40 is not limited to this. For example, the grinding unit may have a two-axis configuration in which only the rough grinding unit 80 and the finish grinding unit 100 are provided, or a one-axis configuration in which only the finish grinding unit 100 is provided.

The embodiments disclosed herein should be considered in all respects as illustrative and not restrictive. The above-described embodiments may be omitted, substituted, or modified in various ways without departing from the scope and spirit of the appended claims.

REFERENCE SIGNS LIST 1 Processing device 42 Chuck 80 Rough grinding section 81 Rough grinding wheel 84 Drive section 85 Support 90 Medium grinding section 91 Medium grinding wheel 94 Drive section 95 Support 100 Finish grinding section 101 Finish grinding wheel 104 Drive section 105 Support 110 Measuring section 120 Display panel 140 Dress board W Wafer

Claims (8)

A processing system for an object to be processed, comprising:
A holding unit that holds the object to be processed;
a grinding unit including a grinding tool for grinding the object held by the holding unit and a moving mechanism for moving the grinding tool relative to the object;
A measurement unit for measuring a thickness of the object to be processed;
A display unit that displays a grinding status of the object to be processed,
The object to be treated is a dress board,
The display unit is
A movement amount of the grinding tool relative to the object to be processed; and
A difference between a thickness of the object before grinding and a thickness of the object after grinding;
Display
determining whether grinding of the object to be processed is normal or abnormal based on the difference or a dressing amount of the grinding tool obtained by subtracting the difference from the movement amount;
A processing system , wherein the threshold value of the difference used in the judgment is set according to a combination of the object to be processed and the grinding tool . The processing system according to claim 1, wherein the display unit displays a value obtained by subtracting the difference from the movement amount. A plurality of the grinding portions are provided,
The processing system according to claim 1 , wherein a plurality of the processing objects are prepared according to the grinding tools of each of the grinding units. A method for processing an object to be processed, comprising the steps of:
The object to be treated is a dress board,
Measuring a thickness of the object before grinding;
moving a grinding tool relative to the processing object held by a holding unit and grinding the processing object using the grinding tool;
Measuring the thickness of the object after grinding;
Calculating a difference between a thickness of the object before grinding and a thickness of the object after grinding;
and determining whether grinding of the object to be processed is normal or abnormal based on the difference or a dressing amount of the grinding tool obtained by subtracting the difference from the movement amount of the grinding tool when grinding the object to be processed. The processing method according to claim 4 , further comprising displaying the movement amount and the difference on a display unit. The processing method according to claim 5 , wherein the display unit displays a value obtained by subtracting the difference from the amount of movement. The processing method according to claim 4 , wherein a threshold value of the difference used in the determination is set according to a combination of the object to be processed and the grinding tool. A plurality of grinding units each equipped with the grinding tool are provided,
The processing method according to claim 4 , wherein a plurality of the processing objects are prepared in accordance with the grinding tools of each of the grinding units.

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