TWI583495B - Measuring device and measuring method of work thickness and polishing device of work - Google Patents

Description

Measuring device for measuring workpiece thickness, measuring method and grinding device for workpiece

The present invention relates to a measuring device for measuring the thickness of a workpiece, a measuring method, and a polishing device for a workpiece, and more particularly to a measuring device and a measuring method for measuring the thickness of the workpiece in a state in which the workpiece is wet, and using the same A polishing device for a workpiece obtained by the measurement device and the measurement method.

Conventionally, in a typical example of a workpiece for polishing, that is, a manufacturing process of a tantalum wafer, single-side polishing (machining polishing) for processing a wafer to a predetermined thickness is performed in advance, and in particular, high flatness is required. In a wafer having a diameter of 300 mm or more, a double-side polishing step of simultaneously polishing the front and back surfaces of the wafer is usually employed.

Such polishing is greatly affected by the polishing environment such as the replacement period of the polishing auxiliary material and the variation of the device stop timing, and the change in the polishing substitution amount cannot be accurately grasped. Therefore, the polishing time cannot be appropriately set, and there is flatness or light. The density of Light Point Defects (LPD) creates a problem of unevenness.

On the other hand, there has been proposed a method of measuring the thickness of the wafer after polishing, thereby grasping the change in the amount of polishing substitution, and feeding back the change. The polishing formulation is changed to the polishing device or the parameters of the polishing conditions are corrected (for example, refer to Patent Document 1).

[Prior Art Literature]

[Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2003-68689

However, since polishing is performed using polishing slurry, grinding water, or the like in the polishing step, the wafer is wetted after polishing. Therefore, in the method of Patent Document 1, in order to accurately measure the thickness of the wafer, it is necessary to wait for wafer drying. .

Therefore, until a time lag can be generated until the thickness of the wafer can be accurately measured, that is, until the end of the drying step, there is a problem that the wafer to be processed during the period cannot be accurately controlled. The amount of polishing, or the amount of processing of the polishing process is lowered in the case where the polishing of the next wafer is not performed until the drying step is completed in order to accurately control the amount of polishing. In addition, such problems are not only produced in germanium wafers, but are also typically produced in workpieces that are ground by the same method.

The present invention has been made to solve the above problems, and an object of the invention is to provide a measuring device for measuring the thickness of a workpiece and a method for measuring the thickness of the workpiece, which can measure the thickness of the workpiece in a state where the workpiece is wet. Further, an object of the present invention is to provide a polishing apparatus which can ensure a processing amount and can appropriately control a workpiece amount of polishing.

The gist of the present invention is as follows.

The apparatus for measuring the thickness of a workpiece according to the present invention includes: a liquid immersion device that immerses at least a part of the workpiece after polishing in a liquid; and two or more measuring devices that are disposed oppositely and measurable until the workpiece is immersed The distance from the surface of the portion of the liquid.

Further, in the measuring device for the thickness of the workpiece of the present invention, it is preferable to further include a supporting member for fixing the measuring device.

Further, in the measuring device for measuring the thickness of the workpiece of the present invention, it is preferable that the measuring device has a cap at the tip end.

Further, in the apparatus for measuring the thickness of the workpiece of the present invention, it is preferable that the liquid immersion device is a groove in which the workpiece can be accommodated inside.

Further, in the measuring device for measuring the thickness of the workpiece of the present invention, it is preferable that the groove is made of quartz or plate glass.

Further, in the apparatus for measuring the thickness of the workpiece according to the present invention, it is preferable that at least a part of the measuring device is inserted into the groove, and a gap is formed between the groove and the measuring device.

Further, in the apparatus for measuring the thickness of the workpiece according to the present invention, it is preferable that the liquid immersion device is a liquid supply pipe capable of supplying the liquid so that at least a part of the workpiece is immersed in the liquid.

Further, in the apparatus for measuring the thickness of the workpiece according to the present invention, it is preferable that the liquid supply tube includes a liquid supply amount adjusting unit that can adjust the amount of the supplied liquid.

Further, in the apparatus for measuring the thickness of the workpiece according to the present invention, it is preferable to further include a liquid introduction pipe that is disposed adjacent to the measurement portion of the thickness of the workpiece and that is opposed to each other across the workpiece, and the measurement At least a top end of the device is inserted into the liquid introduction tube.

Here, in the apparatus for measuring the thickness of the workpiece of the present invention, it is preferable that the liquid is water.

Further, in the measuring device for measuring the thickness of the workpiece of the present invention, it is preferable that the measuring device is an optical spectroscopic interference type measuring device.

Further, in the apparatus for measuring the thickness of the workpiece according to the present invention, it is preferable that the deformation amount of the groove is 50 nm or less at the time of measuring the thickness of the workpiece.

Here, the "deformation amount of the groove" refers to the amount of deformation in the point on the line on which the two measuring devices are opposed, and is the maximum displacement in the period of the measurement time.

Further, in the measuring device for measuring the thickness of the workpiece of the present invention, it is preferable that the reinforcing plate is disposed on the groove.

Further, in the apparatus for measuring the thickness of the workpiece according to the present invention, preferably, the tank has a liquid discharge unit, a liquid discharge amount measuring device that measures a liquid discharge amount from the liquid discharge unit, and a control unit that is determined based on the measured The liquid discharge amount adjusts the liquid discharge amount.

Here, the method for measuring the thickness of the workpiece of the present invention is characterized by comprising the steps of: immersing at least a portion of the ground workpiece in the liquid; in a state where at least a portion of the workpiece is immersed in the liquid, by Two or more measuring devices measure the thickness of the workpiece, and the two or more measuring devices are opposed to each other across the workpiece It is configured and the distance up to the surface of the portion of the workpiece immersed in the liquid can be determined.

Further, a polishing apparatus for a workpiece according to an aspect of the present invention includes: a receiving portion that receives thickness information of the workpiece measured by the measuring device for the thickness of the workpiece; and an arithmetic unit that is based on the thickness of the workpiece Information, change the grinding recipe or correct the parameters of the grinding conditions.

Further, a polishing apparatus for a workpiece according to another aspect of the present invention includes: a receiving portion that receives thickness information of the workpiece measured by a method of measuring a thickness of the workpiece; and an arithmetic unit that is based on the workpiece Thickness information, change of grinding recipe or correction of parameters of grinding conditions.

According to the present invention, it is possible to provide a measuring device for measuring the thickness of a workpiece in a state where the workpiece is wet, and a method for measuring the thickness of the workpiece. Further, according to the present invention, it is possible to provide a polishing apparatus which can ensure the amount of processing and can appropriately control the amount of polishing.

1‧‧‧Measurement device for workpiece thickness

2‧‧‧Sink

2a‧‧‧ recess

2b‧‧‧Enhanced board

3‧‧‧Measurer

4‧‧‧Support members

5‧‧‧ water

6‧‧‧ Cover

7‧‧‧ air layer

8‧‧‧ gap

9‧‧‧Liquid supply tube

10‧‧‧Liquid introduction tube

11‧‧‧ water film

W‧‧‧Workpiece (wafer)

Fig. 1 (a) is a schematic perspective view of a measuring device for a workpiece thickness according to a first embodiment of the present invention. Fig. 1 (b) is a view showing a main part of a measuring device for a workpiece thickness according to a first embodiment of the present invention.

Fig. 2 (a) is a schematic perspective view of a measuring device for measuring the thickness of a workpiece according to a second embodiment of the present invention. Fig. 2 (b) is a view showing the thickness of a workpiece according to a second embodiment of the present invention. A diagram of the main part of the measuring device.

Fig. 3 (a) is a schematic perspective view of a measuring device for measuring the thickness of a workpiece according to a third embodiment of the present invention. Fig. 3 (b) is a perspective view showing a main part of a measuring device for a workpiece thickness according to a third embodiment of the present invention.

Fig. 4 (a) is a schematic perspective view of a measuring device for a workpiece thickness according to a fourth embodiment of the present invention. Fig. 4 (b) is a perspective view showing a main part of a measuring device for a workpiece thickness according to a fourth embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Measurement device for workpiece thickness)

<First embodiment>

Fig. 1 (a) is a schematic perspective view of a device for measuring the thickness of a workpiece according to a first embodiment of the present invention, and Fig. 1 (b) is a view showing a main part of a device for measuring a thickness of a workpiece according to a first embodiment of the present invention. As shown in Fig. 1(a), the workpiece thickness measuring device 1 has a water tank 2 filled with water (pure water). The water tank 2 is a liquid immersion device that can accommodate a polished workpiece (in the present embodiment, a silicon wafer) W and can immerse the whole or a part of the wafer W in water.

Further, as shown in Fig. 1(a), the measuring device 1 for the workpiece thickness includes two or more measuring instruments (two in the illustrated example), and the measuring device 3 is disposed in the opposite direction and can be measured up to the crystal. The distance from the surface of the portion of the circle W that is immersed in the liquid. That is, one of the measuring devices 3 can be measured from the side of the measuring device 3 to the wafer W The distance from the surface of the wafer 3 to the surface on the back side of the wafer W can be measured.

Further, as shown in FIG. 1(a), the measuring device 1 for the thickness of the workpiece further includes a supporting member 4 for fixing the measuring device 3. In the illustrated example, the support member 4 includes four plate-shaped members having high rigidity between the four pillars and the connecting pillars that surround the water tank 2, and the measuring device 3 is fixed to the two opposing plates. On the member, the distance between the opposing measuring devices 3 is kept constant.

Thereby, the measuring device 3 measures the distance from the predetermined position of the wafer W up to the front surface of the wafer W and the distance up to the surface on the back side of the wafer W, thereby using, for example, a not shown The arithmetic unit can determine the thickness of the wafer W at the predetermined position.

Here, as shown in FIG. 1(b), the water tank 2 is filled with water (pure water) 5, and the wafer W is placed on the opposite measuring device 3 so that the entire surface is immersed in the water 5. between. The wafer W is transferred to water using a transfer unit (not shown) in a state where it is wetted by polishing slurry, grinding liquid, or the like after polishing.

Hereinafter, the operation and effect of the first embodiment will be described.

According to the workpiece thickness measuring apparatus 1 of the present embodiment, first, the wafer W is transferred to water in a wet state, and the thickness of the wafer W can be measured while the wafer W is immersed in water. Therefore, the amount of processing of the polishing process can be ensured as compared with the case where the thickness of the wafer W is measured after the wafer W is dried. Further, by changing the thickness of the wafer W before polishing, the change in the polishing substitution amount is grasped, and the change is fed back to the polishing apparatus to change the polishing recipe or the polishing condition. The number is corrected, whereby the amount of polishing of the polishing apparatus can be appropriately controlled. Further, the amount of polishing substitution can be grasped by, for example, one wafer W, and for example, a plurality of wafers W can be statistically observed and grasped. Therefore, by using the measurement results of the present embodiment, the flatness (particularly the flatness of the outer peripheral portion) or the density of the LPD of the wafer W after polishing can be improved. Further, by managing the amount of polishing substitution, the amount of the disposable polishing slurry can be appropriately used, and the cost of the material can be reduced.

Further, by moving the wafer W in the radial direction of the wafer W by a transfer unit (not shown), the thickness of the wafer W in all the planes within a certain diameter range of the wafer W can be measured. In this case, it is preferable that the water tank 2 is a large volume including the movement range of the wafer W. On the other hand, the thickness can be measured within the radius of the wafer W. Alternatively, the measuring device 3 can be moved to measure the thickness of the wafer W at any position. In this case, the measuring device 3 is moved while keeping the distance between the opposing measuring devices 3 constant.

Further, by providing a mechanism for rotating the wafer W in the transfer portion, thickness measurement can be performed such as thickness measurement at an arbitrary position of the wafer W, radius measurement in an arbitrary direction, thickness measurement in a diameter range, and crystal The thickness of the circle W in the plane in the circumferential direction was measured.

Further, in the present embodiment, the thickness of the wafer W is calculated based on the distance from the surface of the wafer W using the two opposing measuring instruments 3. For example, in a method of measuring the thickness of the wafer W by the interference of the reflected light from the front and back sides by irradiating a laser or the like from one side of the wafer W, when the impurity concentration in the germanium substrate is high, the light is high. Cannot pass to the back, there is a case where the thickness of the wafer cannot be evaluated, but this In the embodiment, the thickness of the wafer W can be measured regardless of the impurity concentration of the wafer W.

Here, in the present invention, it is preferable that the liquid is water as in the above embodiment, and it is particularly preferable to use it as pure water. The reason for this is that light is transmitted and does not chemically react with the wafer W or the measuring device 3.

Further, the measuring device 3 is preferably an optical spectroscopic interference type measuring device. This is because the distance from the measuring device 3 to the surface of the wafer W can be measured even with a liquid such as water.

Here, in the example shown in FIGS. 1(a) and 1(b), since the measuring device 3 is disposed outside the water tank 2, it is preferable to form the water tank 2 by using a material that transmits light.

Further, as shown in FIGS. 1(a) and 1(b), the concave portion 2a is provided in the water tank 2. By shortening the distance between the wafer W and the measuring device 3, the measuring device 3 can be used with high precision.

In addition, as shown in FIG. 1(a) and FIG. 1(b), when the air layer 7 is interposed between the water portion and the measuring device 3, it is considered that water pressure occurs due to movement of the wafer W in water or the like. When the change is made, the water tank 2 is deformed, the ratio of the distance between the air layer 7 and the water portion is changed, and a slight deviation occurs in the optical appearance distance. The inventors have newly found that by controlling the deviation, the thickness of the wafer W can be further measured with high precision.

Therefore, in the embodiment shown in Figs. 1(a) and 1(b), it is preferable that the water tank 2 is made of quartz or plate glass. The reason is that quartz or plate glass is a highly rigid material, so that the deformation of the water tank can be reduced. Thereby, the above-described problem caused by the interposition of the air layer 7 can be avoided.

Moreover, in order to increase the rigidity of the water tank 2, it is preferable to thicken the thickness of the water tank 2, and it is preferable to set it as 8 mm or more, More preferably, it is 10 mm or more, and it is especially preferable to set it as 12 mm or more.

Further, in the apparatus for measuring the thickness of the workpiece of the present invention, it is preferable that the amount of deformation of the groove is 50 nm or less at the time of measuring the thickness of the workpiece. This is because the thickness of the wafer W can be measured with higher precision. Further, the amount of deformation of the groove can be measured using SI-F10 manufactured by Keyence Corporation, etc., but is not particularly limited.

In order to set the amount of deformation of the groove to 50 nm or less, it is preferably a measurement transmission window on the line of the groove in which the two measuring devices 3 are opposed (shown in FIG. 1(a) and FIG. 1(b). In the example, the reinforcing material is provided around the concave portion 2a) of the water tank 2 (in the example shown in Fig. 1 (a) and Fig. 1 (b), the reinforcing plate 2b). The reason for this is that the groove is reinforced by the reinforcing material, and the amount of deformation of the groove can be reduced.

Here, in order to enhance the reinforcing effect, it is preferable that the reinforcing material covers at least the upper and lower sides of the measurement transmission window, and it is more preferable to enhance the entire side surface of the groove. Further, the material of the reinforcing material is preferably a metal such as stainless steel (SUS).

Alternatively, the groove itself may be formed of a metal such as stainless steel in addition to the portion for measuring the transmission window.

Further, in order to set the amount of deformation of the groove to 50 nm or less, it is preferable to use the liquid level in the groove (in the example shown in Fig. 1 (a) and Fig. 1 (b), the water level in the water tank 2) Make adjustments in a certain way.

Specifically, for example, in the example shown in FIGS. 1( a ) and 1 ( b ), a liquid discharge unit (in this example, a drain portion) is preferably provided in a tank (in this example, the water tank 2 ). , The liquid discharge amount (the displacement amount in this example) is measured by the liquid discharge amount measuring device (the displacement measuring device), and the liquid discharge amount (the amount of displacement in this example) is measured based on the measured liquid discharge amount (discharge amount). The control unit controls the amount of liquid supplied (the amount of water supplied) and/or the moving speed of the transfer unit that moves the wafer W to adjust the amount of liquid discharge (discharge amount).

<Second embodiment>

Fig. 2 (a) is a schematic perspective view of a measuring device for measuring the thickness of a workpiece according to a second embodiment of the present invention. Fig. 2 (b) is a view showing a main part of a measuring device for a workpiece thickness according to a second embodiment of the present invention.

As shown in Fig. 2 (a) and Fig. 2 (b), the apparatus for measuring the thickness of the workpiece of the embodiment differs from the embodiment shown in Figs. 1(a) and 1(b) in that: The top end of the device 3 is inserted into the water tank 2, and a gap 8 is provided between the water tank 2 and the measuring device 3. Further, a lid 6 is provided at the distal end of the measuring device 3, and the metal measuring device 3 is prevented from coming into contact with water by the lid 6, and an air layer 7 is formed between the distal end of the measuring device 3 and the lid 6.

According to the second embodiment, the basic configuration is the same as that of the first embodiment, and therefore the same operational effects as those of the first embodiment can be obtained.

Further, according to the second embodiment, the gap 8 is provided between the water tank 2 and the measuring device 3, and the water 5 in the water tank 2 is leaked from the gap 8. Therefore, the water tank 2 is deformed even by fluctuations in water pressure or the like. In other cases, the distance ratio between the air layer 7 and the water portion may be suppressed from changing without interfering with the measuring device 3, thereby suppressing a change in the distance in the optical appearance. Therefore, according to the embodiment, the avoidance factor can be avoided. The problem caused by the air layer 7. Further, according to the second embodiment, the measuring device 3 can be brought close to the wafer W, so that the measurement accuracy can be improved.

Further, in the present embodiment, since the water 5 leaks from the water tank 2, it is preferable to increase the amount of water supplied into the water tank 2, but it is preferable to supply water to a degree slightly larger than the amount leaked from the gap 8. 5, so that the turbulent flow of the water 5 is not generated and the wafer W is not vibrated so that measurement errors do not occur.

<Third embodiment>

Fig. 3 (a) is a schematic perspective view of a measuring device for measuring the thickness of a workpiece according to a third embodiment of the present invention. Fig. 3 (b) is a perspective view showing a main part of a measuring device for a workpiece thickness according to a third embodiment of the present invention.

The third embodiment is an example in which the water tank 2 itself is not used in order to eliminate the deformation of the water tank 2, and the deformation causes a change in the ratio of the distance between the air layer 7 and the underwater portion in the optical appearance.

Here, the liquid supply pipe 9 includes a liquid supply amount adjusting unit that can adjust the amount of the supplied water 5, and by slightly adjusting the supply amount of the water 5, it can be formed at a position where the thickness of the wafer W is measured. The water film 11 is in a state where the measurement site is always immersed in the water 5.

Further, for example, as shown in FIG. 3(a), the water 5 is introduced into the liquid introduction pipe 10 from one end portion of the cylindrical liquid introduction pipe 10, and flows through the liquid introduction pipe 10.

According to the third embodiment, at least the portion of the wafer W whose thickness is measured is immersed in water. Therefore, the wafer W can be immersed in water in the same manner as in the first embodiment and the second embodiment. Wafer W The thickness can be compared with the case where the thickness of the wafer W is measured after drying the wafer W, and the amount of processing of the polishing process can be ensured. Further, by comparing the thickness of the wafer W before polishing, the change in the amount of polishing substitution is grasped, and the change is fed back to the polishing apparatus to change the polishing recipe or to correct the parameters of the polishing conditions. The amount of grinding of the polishing apparatus is appropriately controlled. By using the measurement results of the present embodiment, the flatness (particularly the flatness of the outer peripheral portion) or the density of the LPD of the wafer W after polishing can be improved. Further, by managing the amount of polishing substitution, the amount of the disposable polishing slurry can be appropriately used, and the cost of the material can be reduced.

Further, in the third embodiment, the wafer W is moved in the radial direction of the wafer W by a transfer unit (not shown), whereby the wafer W in all the planes within a certain diameter range of the wafer W can be measured. thickness. Further, according to the present embodiment, the thickness of the wafer W can be measured irrespective of the impurity concentration of the wafer W in the same manner as in the first embodiment and the second embodiment.

Further, according to the third embodiment, since the water tank 2 is not used, an error occurs in the measurement of the thickness of the wafer W due to the deformation of the water tank 2 as described above, so that the air layer 7 can be avoided. The bad situation. Further, the measuring device 3 can be used with high precision by bringing the measuring device 3 closer to the wafer W.

<Fourth embodiment>

Fig. 4 (a) is a schematic perspective view of a measuring device for a workpiece thickness according to a fourth embodiment of the present invention. Fig. 4 (b) is a perspective view showing a main part of a measuring device for a workpiece thickness according to a fourth embodiment of the present invention.

As shown in Fig. 4 (a), the fourth embodiment is in the following aspects and the third embodiment. The wafer W is disposed so that the diameter direction becomes the horizontal direction (the direction perpendicular to the gravity), and the two measuring instruments 3 are disposed so as to face each other across the wafer W.

In the fourth embodiment, the same operational effects as those in the third embodiment can be obtained.

In particular, according to the fourth embodiment, the water film 11 can be easily held on the upper surface of the wafer W. Further, the water film 11 can be held by supplying water at a relatively high pressure to the lower surface of the wafer W.

(Method for measuring the thickness of the workpiece)

The method for measuring the thickness of the workpiece according to the embodiment of the present invention includes at least a part of the wafer W after polishing as described in FIG. 1(a), FIG. 1(b) to FIG. 4(a), and FIG. 4(b). A step of immersing in a liquid such as pure water. As a method of immersing the wafer W in a liquid, for example, as shown in FIG. 1(a), FIG. 1(b), FIG. 2(a), and FIG. 2(b), the wafer W can be used using the water tank 2. It is disposed in the water tank 2, or may be in the form of a liquid supply pipe 9 by, for example, increasing the water pressure as shown in Figs. 3(a), 3(b), 4(a), and 4(b). A water film 11 is formed on a part of the circle W. In addition, other methods can also be used.

Further, in a state in which at least a part of the wafer W is immersed in a liquid, the thickness of a portion of the wafer W immersed in the liquid is measured by two or more measuring devices 3, and the measuring device 3 is partitioned. The wafer W is disposed opposite to each other, and the distance up to the surface of the wafer W can be measured.

According to the method for measuring the thickness of the workpiece according to the present embodiment, the thickness of the wafer W can be measured while the wafer W is wet, and the polishing can be ensured as compared with the case where the thickness of the wafer W is measured after the wafer W is dried. The amount of processing for batch processing. In addition, By changing the thickness of the wafer W before polishing, the change in the amount of polishing substitution is grasped, and the change is fed back to the polishing apparatus to change the polishing recipe or to correct the parameters of the polishing conditions. The amount of grinding of the polishing device is controlled. By using the measurement results of the method of the present embodiment, the flatness (particularly the flatness of the outer peripheral portion) or the density of the LPD of the wafer W after polishing can be improved. Further, by managing the amount of polishing substitution, the amount of the disposable polishing slurry can be appropriately used, and the cost of the material can be reduced.

(grinding device for workpiece)

A polishing apparatus for a workpiece according to an embodiment of the present invention includes a receiving unit (not shown) that receives thickness information of the wafer W measured by the measuring device and the measuring method of the workpiece thickness, and a computing unit (not shown) The polishing recipe is changed or the parameters of the polishing conditions are corrected based on the thickness information of the wafer W received by the receiving unit. Specifically, the calculation unit can correct the polishing time and the like, for example. Further, the polishing device may be a double-side polishing device or a single-sided polishing device.

According to the polishing apparatus for a workpiece of the present embodiment, the amount of processing can be ensured and the amount of polishing can be appropriately controlled. Therefore, the flatness of the workpiece after polishing (especially the flatness of the outer peripheral portion) can be improved, and the density of defects such as LPD can be reduced.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments. Further, the embodiments of the present invention are described below, but the present invention is not limited to the examples.

[Examples]

(Example 1)

A test for measuring the thickness of the polished tantalum wafer was performed using two different types of measuring instruments that measure the distance up to the wafer. Grinding uses a conventional single-sided grinding device. As shown in Table 1 below, two types of substrates, p ^- and p ⁺⁺ having a diameter of 300 mm, were used for the tantalum wafer. Further, as a type of measuring device that evaluates the interference of reflected light on the back surface of the wafer in water, an optical micrometer (Optical MicroGauge) manufactured by Hamamatsu Photonics Co., Ltd. (Conventional Example 1) is used. A SI-F10 (Inventive Example 1) manufactured by Keyence Corporation was used as a measuring device that can be used to measure the distance up to the surface of the wafer in water. In addition, as a comparison object, the thickness of the wafer (Comparative Example) was measured after drying using Nano Metro manufactured by Kuroda Corporation. In the first embodiment and the comparative example, the measurement was carried out using a device of the type in which the wafer was sandwiched between two measuring devices as shown in Figs. 1(a) and 1(b). On the other hand, in the conventional example, the measuring instrument is placed only on one side of the wafer.

Hereinafter, the evaluation results are shown in Table 1.

As shown in Table 1, the thickness of the p ^- substrate can be measured with high precision in both the conventional example 1 and the invention example 1. However, the thickness of the p ⁺⁺ substrate cannot be measured in the conventional example 1, and On the other hand, in the first invention, the thickness of the wafer can be accurately measured.

(Example 2)

Then, the thickness of the wafer after single-side polishing is measured, and this is fed back to the single-sided polishing apparatus, and the Site Front Least Square Range (SFQR) at the time of polishing time correction is measured to obtain a single-sided surface. The difference (ΔSFQR) of SFQR before and after grinding. Here, the single-sided polishing apparatus includes a receiving unit that receives the measured thickness information of the wafer and a calculation unit that performs polishing time correction based on the thickness information of the received wafer, and the other configuration is the same as that of the normal single-sided polishing apparatus. . Further, the tantalum wafer for polishing was set to a p ^- type tantalum wafer having a diameter of 300 mm. In addition, the SFQR is an in-plane plane obtained by using the least squares calculation data in a set portion as a reference plane, and is placed horizontally from the + side of the plane (that is, the main surface of the wafer is placed upwards). In the case of the upper side) and the - side (the lower side in the case where the main surface of the wafer faces upward and horizontally), the sum of the absolute values of the respective maximum displacement amounts is expressed and is evaluated at each position. In Example 2, a flatness measuring instrument (manufactured by KLA-Tencor Co., Ltd.: Wafer Sight) was used to measure in a part size of 26 × 8 mm ² .

Here, since the polishing rate fluctuates depending on the operation state of the polishing apparatus, the SFQR is evaluated in two cases, which are temporarily stopped, restarted, and continuously operated. The evaluation results are shown in Table 2 below. In Table 2, the invention example 2 is a case where the feedback is performed, and the conventional example 2 is a case where the feedback is not performed. In addition, the case where the sign of ΔSFQR in Table 2 is positive indicates that the SFQR deteriorates after one-side polishing. Further, in the same manner as in Inventive Example 1, the thickness of the wafer after single-side polishing was measured.

As shown in Table 2, in the conventional example 2, since the polishing time is made constant, when the single-side polishing apparatus is stopped and restarted, ΔSFQR is large and the flatness is lowered. On the other hand, in the second invention, the thickness information of the polished wafer measured is fed back to the single-side polishing apparatus to adjust the polishing time (520 sec). Therefore, even after the restart and restart, the ΔSFQR is small. And the decrease in flatness is suppressed.

(Example 3)

Then, the thickness of the wafer after single-side polishing was measured, and this was fed back to the single-sided polishing apparatus, and the LPD density at the time of correction of the polishing time was evaluated. The evaluation of the LPD density was carried out using a Particle Counter (manufactured by KLA-Tencor Co., Ltd., SP2). Here, the single-sided polishing apparatus includes a receiving unit that receives the measured thickness information of the wafer and a calculation unit that performs polishing time correction based on the thickness information of the received wafer, and the other configuration is the same as that of the normal single-sided polishing apparatus. . Further, the tantalum wafer for polishing was set to a p ^- type tantalum wafer having a diameter of 300 mm. Since the polishing rate fluctuates depending on the operation state of the polishing apparatus, the LPD density is evaluated in two cases, which are temporarily stopped, restarted, and continuously operated. The evaluation results are shown in Table 3 below. In Table 3, the invention example 3 is a case where the feedback is performed, and the conventional example 3 is a case where the feedback is not performed. Further, in the same manner as in Inventive Example 1, the thickness of the wafer after single-side polishing was measured.

As shown in Table 3, in the conventional example 3, since the polishing time is made constant, when the single-side polishing apparatus is stopped and restarted, the LPD density is large and a large number of defects are generated, but in the third embodiment, The measured thickness information of the polished wafer is fed back to the single-side polishing apparatus to adjust the polishing time (520 sec), so that the generation of LPD can be suppressed even after the restart and restart. Further, by managing the amount of polishing substitution, the amount of the disposable polishing slurry can be appropriately used, and the cost of the material can be reduced.

(Example 4)

Then, when the material or thickness of the water tank is changed, the measurement error of the thickness of the wafer and the amount of deformation of the water tank are monitored and evaluated. The crucible wafer for polishing was a p ⁺⁺ type substrate having a diameter of 300 mm. Grinding uses a conventional single-sided grinding device. Here, the measurement error is measured by using the SI-F10 manufactured by Keyence Corporation in the apparatus shown in FIG. 1 and using Nanometro manufactured by Kuroda Corporation. When the thickness of the wafer is measured after drying, the measurement is performed 10 times, and the maximum value of the difference between the measurement results is referred to as a measurement error. Further, the SI-F10 manufactured by Keyence Corporation was used, and the amount of deformation of the water tank was monitored during the measurement time, and the maximum displacement in the period was set as the deformation amount of the water tank.

The evaluation results are shown in Table 4 below. In addition, in Table 4, the "measurement error" is represented by the relative index when the acrylic resin (thickness: 8 mm) is 100, and the small value indicates that the "measurement error" is small. Further, as shown in FIG. 1(a) and FIG. 1(b), the metal reinforcement is performed by attaching a stainless steel reinforcing plate to the water tank, and the control of the displacement is to adjust the water supply amount by monitoring the displacement. The moving speed of the wafer is performed.

As shown in Table 4, when quartz is used, the amount of deformation of the water tank is greatly reduced, whereby the measurement error can be greatly improved. In addition, the more you know When the thickness of the water tank is increased, the deformation amount of the water tank becomes smaller, and the measurement error becomes smaller.

Further, it is understood that the amount of deformation of the water tank is further reduced by the metal reinforcement, and the measurement error is further reduced. Further, it is understood that the amount of deformation of the water tank is further reduced by controlling the amount of water to be drained, and the measurement error is further reduced.

(Example 5)

Then, the error in the measurement of the wafer thickness when using the water tank shown in FIGS. 2(a) and 2(b), and the use of the water tank shown in FIG. 1(a) and FIG. 1(b) (wherein The error in the measurement of the wafer thickness at the time of having the reinforcing plate was compared and evaluated. The evaluation method is the same as that of the fourth embodiment. In addition, the material and thickness of the water tank are set to be the same. In addition, in Table 5, the "measurement error" is represented by the relative value when the case of FIG. 1 (a) and FIG. 1 (b) is 100, and the small value shows that the error is small. Further, in the present embodiment, the displacement control is not performed.

It can be seen that when the apparatus shown in FIGS. 2( a ) and 2 ( b ) is used, since the water tank has a gap and the deformation of the water tank does not interfere with the measuring device, as shown in Table 5, the measurement can be greatly reduced. Error.

(Example 6)

Then, the wafer thickness when using the device shown in FIGS. 3(a) and 3(b) The measurement error was compared with the measurement error when using the water tank shown in Fig. 1 (a) and Fig. 1 (b) (in which the reinforcing plate was not provided). The evaluation methods were the same as in Example 4 and Example 5. Further, in Table 6, the "measurement error" is expressed as a relative value when the case of Fig. 1 (a) and Fig. 1 (b) is set to 100, and the small value indicates that the error is small. Further, in the present embodiment, the displacement control is not performed.

As shown in Table 6, when the apparatus shown in Figs. 3(a) and 3(b) is used, since the water tank itself which is the cause of the measurement error is not used, the measurement can be greatly reduced. error.

(Example 7)

Then, in the same manner as in the second embodiment, the thickness of the wafer after the single-side polishing was measured, and the thickness was fed back to the single-side polishing apparatus to measure the surface area of the least squared value at the time of the polishing time correction (Site Front Least Square Range). , SFQR), the difference (ΔSFQR) of SFQR before and after single-side polishing was obtained. The test was carried out in the following three cases, that is, when metal reinforcement and displacement control were not performed, metal reinforcement was only performed, and metal reinforcement and displacement control were performed. Further, in the same manner as in Inventive Example 1, the thickness of the wafer after single-side polishing was measured.

In Table 7, the evaluation result is expressed by the relative value of the standard deviation of ΔSFQR, and the case where the metal reinforcement and the displacement control are not performed is set to 100, and the smaller the value is not The smaller the average, the better.

Further, metal reinforcement and displacement control were carried out by the same method as in Example 4.

As shown in Table 7, it is understood that the relative value of the standard deviation of ΔSFQR can be further reduced by performing metal reinforcement, and the relative value of the standard deviation of ΔSFQR can be further reduced by controlling the metal reinforcement and the displacement.

1‧‧‧Measurement device for workpiece thickness

2‧‧‧Sink

2a‧‧‧ recess

2b‧‧‧Enhanced board

3‧‧‧Measurer

4‧‧‧Support members

Claims (12)

A device for measuring the thickness of a workpiece, comprising: a liquid immersion device for immersing at least a part of the polished workpiece in a liquid; and two or more measuring devices disposed oppositely and in a state of interposing the workpiece And measuring a distance up to a surface of the portion of the workpiece immersed in the liquid, the liquid immersion device being a groove capable of accommodating the workpiece inside, and the measuring device for the thickness of the workpiece having A control unit that adjusts the liquid level in the tank so as to be constant. The apparatus for measuring the thickness of a workpiece according to claim 1, further comprising a support member for fixing the measuring device. The apparatus for measuring the thickness of a workpiece according to the first or second aspect of the invention, wherein the measuring device is provided with a lid at a tip end. The apparatus for measuring the thickness of a workpiece according to the first or second aspect of the invention, wherein the groove is made of quartz or plate glass. The apparatus for measuring the thickness of a workpiece according to the first or second aspect of the invention, wherein the liquid is water. The apparatus for measuring the thickness of a workpiece according to the first or second aspect of the invention, wherein the measuring device is an optical spectroscopic interference type measuring device. The apparatus for measuring the thickness of a workpiece according to the first or second aspect of the invention, wherein the deformation amount of the groove is 50 nm when the thickness of the workpiece is measured. under. The apparatus for measuring the thickness of a workpiece according to claim 7, wherein the reinforcing plate is disposed on the groove. The apparatus for measuring a thickness of a workpiece according to claim 7, wherein the tank has a liquid discharge unit, a liquid discharge amount measuring device that measures a liquid discharge amount from the liquid discharge unit, and a control unit based on the measurement The liquid discharge amount adjusts the liquid discharge amount. A method for measuring a thickness of a workpiece, comprising: immersing at least a portion of the polished workpiece in a liquid in a tank capable of housing the workpiece; and immersing at least a portion of the workpiece In the state of the liquid, the thickness of the workpiece is measured by two or more measuring instruments, and the two or more measuring instruments are disposed to face each other across the workpiece, and the immersion of the workpiece can be measured. The distance from the surface of the portion in the liquid; and adjusted so that the liquid level in the groove is constant. A grinding apparatus for a workpiece, comprising: a receiving portion that receives thickness information of the workpiece measured by a measuring device for a workpiece thickness according to any one of claims 1 to 9; The calculation unit changes the polishing recipe or corrects the parameters of the polishing conditions based on the thickness information of the workpiece. A grinding apparatus for a workpiece, comprising: a receiving portion for receiving a thickness of a workpiece as described in claim 10 The thickness information of the workpiece measured by the measuring method; and the calculation unit corrects the polishing recipe or corrects the parameters of the polishing condition based on the thickness information of the workpiece.