JP2020104211A - Double-head grinding method - Google Patents

Abstract

To provide a double-head grinding method allowing for acquisition of a ground article having favorable nanotopography and desired thickness.SOLUTION: The double-head grinding method comprises: a first grinding step of grinding a first wafer until the thickness thereof becomes a prescribed one while feeding the prescribed amount of grinding fluid to the first and second principal surfaces of the first wafer; a nanotopography measurement step of measuring nanotopography of the first wafer; and a second grinding step of adjusting a grinding condition so that the nanotopography of a second wafer approaches zero on the basis of the measurement result of the above measurement step, and performing a grinding operation until the thickness of the second wafer becomes the prescribed one. The second grinding step includes adjusting a ratio of the feeding amount of the grinding fluid to the first principal surface of the second wafer to that of the grinding fluid to the second principal surface while maintaining total feeding amount of the grinding fluid in the first grinding step, and grinding the second wafer.SELECTED DRAWING: Figure 9

Description

The present invention relates to a double head grinding method.

Conventionally, an object to be ground is ground by rotating the object to be ground and supplying a grinding liquid to both main surfaces of the object to be ground, and bringing a grinding wheel of a grinding wheel into contact with both main surfaces of the object to be ground. A double-sided grinding method is known (for example, refer to Patent Document 1).
The method described in Patent Document 1 reduces the hydroplaning effect between the object to be ground and the grindstone by reducing the supply amount of the grinding fluid as the height of the grindstone decreases, and each grinding target The grinding condition of the object is kept constant.

JP, 2009-16842, A

However, in the method as disclosed in Patent Document 1, the temperature of the processing atmosphere changes due to the change in the flow rate of the grinding fluid, which may lead to a change in quality such as thickness.

An object of the present invention is to provide a double-sided grinding method in which a nanotopography is good and an object to be ground having a desired thickness can be obtained.

The double-sided grinding method of the present invention, by rotating the object to be ground and supplying the grinding liquid to both main surfaces of the object to be ground, and bringing the grindstone of the grinding wheel into contact with both main surfaces of the object to be ground, respectively. Using a double-sided grinder equipped with a grinding means for grinding the object to be ground and a thickness measuring means for measuring the thickness of the object to be ground, based on the measurement result of the thickness measuring means, A double-headed grinding method for grinding a material to a predetermined thickness, wherein a predetermined amount of a grinding liquid is supplied to both main surfaces of the first material to be ground, Based on a first grinding step of performing grinding until the thickness reaches the predetermined thickness, a nanotopography measuring step of measuring the nanotopography of the first workpiece, and a measurement result of the nanotopography measuring step. A second grinding step in which the grinding conditions are adjusted so that the nanotopography of the second object to be ground approaches 0, and grinding is performed until the thickness of the second object to be ground reaches the predetermined thickness. In the second grinding step, while maintaining the total amount of the grinding fluid supplied in the first grinding step, the second grinding step supplies the grinding fluid to the one main surface of the second object to be ground and the other. It is characterized in that the second object to be ground is ground by adjusting the ratio with the supply amount of the grinding liquid to the main surface.

In the double-sided grinding method of the present invention, as the thickness measuring means, a pair of contactors respectively contacting both main surfaces of the object to be ground are provided, and a signal corresponding to the position of the pair of contactors is output. It is preferable to use a differential transformer type displacement gauge for measuring the thickness of the object to be ground.

In the double-sided grinding method of the present invention, the second grinding step is based on a measurement result of the nanotopography measuring step of the first object to be ground, and the first object to be ground in the second object to be ground. It is preferable to adjust the ratio so that the amount of the grinding liquid supplied to the main surface on the concave side of the object is larger than the amount of the grinding liquid supplied to the other main surface.

According to the present invention, an object to be ground having good nanotopography and a desired thickness can be obtained.

1 is a schematic diagram of a double-sided grinding device according to a related technique and an embodiment of the present invention. Partially enlarged view of the double-sided grinding machine The block diagram of the control system of the said double-head grinding apparatus. 7 is a graph showing the result of Experiment 1 for guiding the present invention and showing the relationship between the supply amount of the grinding fluid to each of the first and second main surfaces and the nanotopography at the wafer center. The graph which shows the relationship between the supply amount of the grinding liquid with respect to each of the 1st, 2nd main surface of the wafer obtained in the said experiment 1, and the thickness of a wafer center. 6 is a graph showing the relationship between the measurement environment temperature and the measurement value of the differential transformer type displacement meter, which is the result of Experiment 2 for guiding the present invention. 6 is a graph showing the result of Experiment 3 for guiding the present invention, showing the relationship between the supply ratio of the grinding liquid to each of the first and second main surfaces and the nanotopography at the wafer center. 6 is a graph showing the result of Experiment 3 and showing the relationship between the supply ratio of the grinding liquid to each of the first and second main surfaces and the thickness of the wafer center. The flowchart of the double-sided grinding method which concerns on the said one Embodiment.

[Related Technology of the Present Invention]
First, a related technique of the present invention will be described.
[Configuration of double-headed grinding machine]
As shown in FIGS. 1 to 3, the double-headed grinding device 1 includes a grinding means 2, a differential transformer type displacement meter 3 as a thickness measuring means, a processing chamber 4, and a control means 5.

The grinding means 2 includes a carrier ring 21, a wafer rotating means 22, first and second grinding wheels 23 and 24, first and second wheel rotating means 25 and 26, and first and second wheels. It is provided with advancing/retreating means 27, 28 and a grinding fluid supply means 29.

The carrier ring 21 is formed in an annular shape and holds the wafer W therein.
The wafer rotating means 22 is controlled by the control means 5 and rotates the carrier ring 21 about the center of the wafer W.

The first and second grinding wheels 23, 24 are substantially disc-shaped wheel bases 23A, 24A, and a plurality of grindstones 23B, 24B provided at predetermined intervals along the outer edge of one surface of the wheel bases 23A, 24A. It has and. Grinding fluid supply holes 23C and 24C are provided at the centers of the wheel bases 23A and 24A so as to penetrate both sides of the wheel bases 23A and 24A.
The first and second wheel rotating means 25 and 26 are controlled by the spindles 25A and 26A for holding the first and second grinding wheels 23 and 24 at their tips and the control means 5, respectively. It is provided with rotating motors 25B and 26B for rotating. The first wheel rotating means 25 is provided on the left side of the wafer W in FIG. 1, and the second wheel rotating means 26 is provided on the right side.
The first and second wheel advancing/retreating means 27, 28 are controlled by the control means 5 to advance/retreat the first and second wheel rotating means 25, 26 with respect to the wafer W.

The grinding fluid supply means 29 is controlled by the control means 5 and is fed into the first and second grinding wheels 23, 24 through the grinding fluid supply holes 23C, 24C of the first and second grinding wheels 23, 24. , Supply grinding fluid.

The differential transformer type displacement meter 3 includes a pair of signal output means 31, an arm 32 extending downward from each signal output means 31, and a contactor 33 provided at the tip of each arm 32. The pair of contacts 33 are provided so as to contact the first and second main surfaces W1 and W2 of the wafer W, respectively, and move according to the thickness of the wafer W. The signal output means 31 outputs a signal according to the position of each contact 33 to the control means 5.

The processing chamber 4 is formed in a box shape in which at least the wafer W, the first and second grinding wheels 23 and 24, and the differential transformer type displacement meter 3 can be arranged inside. Are prevented from scattering outside the processing chamber 4.

The control means 5 is connected to a memory (not shown) and grinds the wafer W based on various conditions stored in the memory.

[Double-head grinding method of related technology]
Next, a related-art double-sided grinding method using the above-described double-sided grinding apparatus 1 will be described.
First, the first and second grinding wheels 23 and 24 are located at the positions shown by the solid lines in FIG. 1, and the respective contactors 33 of the differential transformer type displacement meter 3 are connected to the first and second main surfaces W1 of the wafer W. , W2, the control means 5 controls the wafer rotating means 22, the first and second wheel rotating means 25 and 26, the first and second wheel advancing and retracting means 27 and 28, and the grinding liquid supplying means. 29, the first and second grinding wheels 23 and 24 are pressed against the first and second main surfaces W1 and W2 of the wafer W, respectively, as shown by the alternate long and two short dashes line in FIG. The wafer W is ground by supplying a grinding liquid into the first and second grinding wheels 23 and 24 and rotating the carrier ring 21 and the first and second grinding wheels 23 and 24.

At this time, as shown in FIG. 2, the control means 5 causes the wafer W and the second grinding wheel 24 to rotate in the clockwise direction (clockwise direction) as viewed from the left side of FIG. 23 is rotated counterclockwise (counterclockwise). Further, the control means 5 supplies the same amount of grinding liquid to the first main surface W1 and the second main surface W2. The rotation directions of the first and second grinding wheels 23 and 24 are not limited to the above directions.
Then, the control means 5 manages the thickness of the wafer W based on the signal output from the differential transformer type displacement meter 3, and when it judges that the wafer W is ground to a predetermined thickness set in advance, the first, The second grinding wheels 23, 24 are separated from the wafer W to finish the grinding.

[History that led to the present invention]
As a result of earnest studies, the present inventor has obtained the following findings.
[Experiment 1]
When the nanotopography of the wafer W obtained by the double-sided grinding method of the above-mentioned related art was measured, it was confirmed that the center of the wafer W had a waviness in the concave direction when viewed from the first main surface W1 side. Note that the nanotopography is a waviness in the nanometer range that exists in a millimeter cycle when the wafer W is placed without adsorption or weak adsorption, and is broadly included in flatness.
The present inventor considered the cause of such a phenomenon, and determined the first and second grinding wheels 23, depending on the flow rate of the grinding fluid, a slight difference in the quality of the grindstones 23B, 24B, the state of the surface of the wafer W, and the like. A difference occurs in the wear of 24 and the state of the cutting edge, and in the central portion of the wafer W where the first and second grinding wheels 23, 24 are constantly in contact during grinding, the difference in the front and back beveling allowance appears particularly significantly, and the central portion It was speculated that a dent or a convex habit would occur on the.
Therefore, as a result of consideration, the present inventor considered that there is a possibility that the nanotopography of the wafer W could be improved by adjusting the supply amount of the grinding liquid, and conducted the following experiment.

First, a double-sided grinding machine 1 (Model: DXSG320 manufactured by Koyo Machine Industry Co., Ltd.) was prepared. Then, the double-sided grinding method of the related art is carried out while supplying the grinding liquid at 1.2 L/min to each of the first main surface W1 and the second main surface W2, and the wafer W having a diameter of 300 mm is predetermined. It grind|pulverized until it became thickness (Experimental example 1-1).
In addition, the supply amount of the grinding fluid to the first main surface W1 and the second main surface W2 is 1.5 L/min each (Experimental example 1-2) and 1.8 L/min each (Experimental example 1-3). 10 wafers W were ground under the same conditions as in Experimental Example 1 except that

Ten wafers W were each ground by the grinding methods of Experimental Examples 1-1 to 1-3, and the first main surface W1 was measured by a nanotopography measuring machine (Model: FT-300U manufactured by Mizojiri Optical Co., Ltd.). The nanotopography of was measured. The nanotopography at this time measures the profile of the unevenness of the surface shape of the first main surface W1 when the position of the outermost peripheral portion of the first main surface W1 is 0 nm. The nanotopography of the center of the surface W1 was measured, profile data of a cross section passing through the center of the wafer W was acquired, and the numerical value of the central portion of the wafer W in the profile was used as an evaluation index. In addition, the value of the outermost peripheral portion is used as a reference (0 nm). The result is shown in FIG.
In FIG. 4, a nanotopography value of less than 0 indicates that the center of the first principal surface W1 is concave, and a value of more than 0 indicates that the center is protruding. Further, the larger the absolute value of the nanotopography, the larger the depression amount and the protrusion amount.

As shown in FIG. 4, it was confirmed that the nanotopography was changed by adjusting the supply amount of the grinding fluid.
From this, it was found that there is a possibility that the nanotopography of the wafer W can be improved by adjusting the supply amount of the grinding liquid to the first main surface W1 and the second main surface W2.

[Experiment 2]
The present inventor has found from the results of Experiment 1 described above that the nanotopography of the wafer W may be improved by adjusting the supply amount of the grinding liquid, but in Experimental Examples 1-1 and 1-3, When the thickness of the center of the wafer W was measured, as shown in FIG. 5, it was confirmed that Experimental Example 1-1 was thicker by approximately 1 μm than Experimental Example 1-3.
Even if the nanotopography of the wafer W can be improved, it is not preferable that the thickness be different from the target value.
Therefore, as a result of consideration by the present inventor, the temperature of the processing chamber 4 changes due to the adjustment of the supply amount of the grinding fluid, and a measurement error of the differential transformer type displacement meter 3 occurs due to this temperature change. The following experiment was conducted on the assumption that the thickness of the wafer W may be different from the target value.

First, the relationship between the measured environmental temperature and the measured value of the differential transformer type displacement meter 3 was examined.
A differential transformer type displacement meter 3 (manufactured by Tokyo Seimitsu Co., Ltd. model: PULCOM series) is prepared, and a temperature sensor (T&D company model: TR-52i is provided in the housing of the signal output means 31 of the differential transformer type displacement meter 3. ) Was attached. The contact 33 was brought into contact with the wafer W having a predetermined thickness, and the thickness was measured while changing the measurement environment temperature. The measurement result is shown in FIG.
As shown in FIG. 6, it was confirmed that the measured value of the differential transformer type displacement meter 3 becomes smaller as the environmental temperature rises.
Therefore, when the differential transformer type displacement meter 3 is used to perform grinding aiming at the same thickness, the higher the temperature in the processing chamber 4, the more the wafer W reaches the target value when the grinding is not progressing. Since the measurement result that the wafer W has arrived is obtained, it can be estimated that the wafer W becomes thicker.

Next, the relationship between the amount of grinding fluid supplied and the temperature in the processing chamber 4 was investigated.
The double-sided grinding machine 1 in which the temperature sensor is attached to the signal output means 31 is prepared, the wafer W is ground under the condition that the supply amount of the grinding fluid is the same as in the experimental example 1-1, and the processing chamber 4 being ground is being processed. The temperature change was measured every second (Experimental example 2-1).
Further, the wafer W was ground under the same conditions as in Experimental Example 2-1 except that the supply amount of the grinding liquid was the same as in Experimental Example 1-3, and the temperature change during grinding was measured (Experimental Example 2- 2).
Table 1 shows the average values of the measurement results.
As shown in Table 1, the temperature of Experimental Example 2-2 was about 0.7° C. lower than that of Experimental Example 2-1. It is considered that the larger the amount of grinding liquid, the higher the cooling effect of the wafer W during grinding, and as a result, the temperature of the processing chamber 4 in Experimental Example 2-2 in which the supply amount was large became lower.

From the results of FIG. 5 and Table 1, it is considered that the higher the temperature of the processing chamber 4, the thicker the wafer W after grinding, which is consistent with the estimation based on the results of FIG. 6 described above.
From this, it was confirmed that if the supply amount of the grinding liquid was adjusted, a measurement error of the differential transformer type displacement meter 3 occurred, and the thickness of the wafer W after grinding was different from the target value.

[Experiment 3]
From the results of Experiment 1, it was found that the nanotopography of the wafer W may be improved by adjusting the supply amount of the grinding liquid to the first main surface W1 and the second main surface W2. Further, from the result of Experiment 2, it was confirmed that the thickness of the wafer W after grinding was different from the target value when the supply amount of the grinding liquid was adjusted.
The present inventor has conducted extensive studies based on the results of Experiments 1 and 2, and as a result, maintains the total amount of the grinding fluid supplied to the first and second main surfaces W1 and W2 while maintaining the first main surface W1. There is a possibility that the nanotopography of the wafer W can be improved and the wafer W having a desired thickness can be obtained by adjusting the ratio of the amount of the grinding liquid supplied to the second main surface W2 to the amount of the grinding liquid supplied to the second main surface W2. Considering that there is, the following experiment was conducted.

The same double-sided grinding machine 1 as in Experiment 2 and a wafer W having a thickness of about 870 μm and a diameter of 300 mm were prepared. Then, based on the conditions shown in Table 2 below, a double-sided grinding method with the same processing contents as the above-mentioned related technology is carried out to grind 10 wafers W each, and a temperature change in the processing chamber 4 during grinding is performed. It measured every 1 second (Experimental example 3-1 to 3-3).
That is, in Experimental Examples 3-1 to 3-3, the total supply amount of the grinding fluid to the first and second main surfaces W1 and W2 was fixed at 2.8 L/min, and the respective main surfaces W1 and W2 were fixed. The ratio of supply amount was adjusted.

Table 3 shows the average value of the measurement results of the temperature in the processing chamber 4.
As shown in Table 3, the maximum temperature difference between Experimental Examples 3-1 to 3-3 is 0.1° C., and if the total supply amount of the grinding fluid is the same, the first and second main surfaces W1 and It was confirmed that the temperature inside the processing chamber 4 hardly changed even if the ratio of the supply amount to W2 was changed.

FIG. 7 shows the calculation result of the nanotopography of the center of the first main surface W1 when the position of the outermost peripheral portion of the first main surface W1 is 0 nm.
As shown in FIG. 7, the ratio of the supply amount to the first and second main surfaces W1 and W2 is changed even while maintaining the total supply amount of the grinding fluid to the first and second main surfaces W1 and W2. Therefore, it was confirmed that the nanotopography can be adjusted. Particularly, by adjusting the ratio so that the amount of the grinding liquid supplied to the first main surface W1 on the concave side is larger than the amount of the grinding liquid supplied to the second main surface W2 on the other side, It was confirmed that the topography can be brought close to 0 nm.

FIG. 8 shows the thickness of the center of the wafer W and its average value.
As shown in FIG. 8, even if the ratio of the supply amount to the first and second main surfaces W1 and W2 is changed, the total supply amount of the grinding fluid to the first and second main surfaces W1 and W2 is the same. If so, it was confirmed that the thickness of the wafer W hardly changed.

From the results shown in FIG. 7 and FIG. 8, while maintaining the total supply amount of the grinding liquid to the first and second main surfaces W1 and W2, the supply amount of the grinding liquid to the first main surface W1 and the second main surface W1 It was confirmed that the wafer W having a desired thickness can be obtained while improving the nanotopography of the wafer W by adjusting the ratio of the supply amount of the grinding liquid to the surface W2.

[Embodiment]
Next, a double-sided grinding method according to an embodiment of the present invention will be described.
First, a related-art double-sided grinding machine 1, a first wafer W _t as a first object to be ground, and a second wafer W _p as a second object to be ground are prepared. The first wafer W _t and the second wafer W _p are substantially the same in material and shape, and are, for example, one silicon single crystal ingot or different silicon single crystal ingots manufactured under the same manufacturing conditions. It was cut out from each.

Then, after the first wafer W _t is set on the carrier ring 21, the control means 5 grinds the first wafer W _t as shown in FIG. 9 (step S1: first grinding step). ). The first wafer W _t used in the first grinding step may be a dummy wafer for preliminary grinding or a product wafer of a previous lot.
In this first grinding step, the differential transformer type displacement meter 3 measures the thickness of the first wafer W _t and outputs a signal according to this measurement result to the control means 5. Control unit 5, first the first wafer W _t, while supplying a predetermined amount of the grinding fluid to the second major surface W1, W2, first the wafer on the basis of a signal from the differential transformer type displacement meter 3 When it is determined that the thickness of W _t has been ground to the predetermined thickness, the grinding is finished. The supply amount of the grinding liquid to the first and second main surfaces W1 and W2 in the first grinding process may be the same or different, but the total supply amount in the first grinding process. Is set to be the same as the total supply amount in the second grinding step described later.

Next, the operator measures the nanotopography of the first wafer W _t using a nanotopography measuring device (not shown) (step S2: nanotopography measuring step).
After that, the control means 5 grinds the second wafer W _p set on the carrier ring 21 (step S3: second grinding step).
In the second grinding step, first, the operator sets the grinding condition such that the nanotopography of the second wafer W _p approaches 0 based on the measurement result of the nanotopography measurement step. Specifically, the worker performs measurement on the first and second main surfaces W1 and W2 based on the nanotopography of the center of the wafer W so that the center nanotopography of the second wafer W _p approaches 0. While maintaining the total supply amount of the grinding liquid, the ratio of the supply amount of the grinding liquid to the first main surface W1 and the supply amount of the grinding liquid to the second main surface W2 is set.
For example, it is known that the higher the ratio of the supply amount to the first main surface W1 is, the smaller the depression amount of the first main surface W1 is, and the first main surface W1 of the first wafer W _t . When the center of the first main surface W1 is depressed, the worker increases the ratio of the supply amount to the first main surface W1, and when the center of the first main surface W1 is protruded, the supply amount to the first main surface W1 is increased. Lower the ratio of. Conversely, when the center of the second main surface W2 of the first wafer W _t is recessed, the operator increases the ratio with respect to the second main surface W2 to set the center of the second main surface W2. When is protruded, the ratio to the second main surface W2 is lowered. That is, the ratio of the supply amount with respect to the main surface having the depressed center may be increased. At this time, the supply ratio of the grinding fluid is preferably 200% or less as a value obtained by dividing the supply amount of the higher ratio by the supply amount of the lower ratio, for example, the supply amount of the higher ratio is 2 L/min. The lower supply amount is preferably 1 L/min.

Then, the control means 5 sets the second wafer W _{p under} the same grinding conditions as in the preliminary grinding step except for the supply ratio of the grinding liquid to the first and second main surfaces W1 and W2 based on the setting of the operator. Grinding.

[Operation and effect of the embodiment]
According to the above embodiment, in the second grinding step, while maintaining the total supply amount of the grinding liquid to the first and second main surfaces W1 and W2 based on the nanotopography of the first wafer W _t , The supply ratio of the grinding fluid to the first and second main surfaces W1 and W2 is adjusted. As described above, by adjusting the supply ratio of the grinding liquid, the nanotopography is improved and the total supply amount of the grinding liquid is maintained, so that the thickness of the second wafer W _p can be adjusted to the first wafer W _t. Can be almost the same as. Therefore, it is possible to obtain the second wafer W _p having a desired thickness and excellent nanotopography.
In particular, since the supply ratio is changed while maintaining the total supply amount of the grinding liquid, the temperatures in the processing chamber 4 in the first grinding process and the second grinding process can be made substantially the same. Therefore, even if the differential transformer type displacement meter 3 in which a measurement error occurs due to the environmental temperature is used, the thickness of the wafer W is made substantially the same as the target value in both the first grinding process and the second grinding process. can do. Since the measurement accuracy of the differential transformer type displacement meter 3 is high, it is possible to obtain the second wafer W _p whose thickness is adjusted with higher accuracy.

[Modification]
The present invention is not limited to the above-described embodiment, and various improvements and design changes can be made without departing from the spirit of the present invention.

For example, the object to be ground may be a wafer other than silicon, or a disk-shaped object other than the wafer W such as ceramics or stone.

Although the second grinding process is performed based on the setting of the operator, it may be performed as follows.
First, in the memory, in a state where the total supply amount of the grinding liquid to the first and second main surfaces W1 and W2 is maintained at a predetermined amount, the supply amount of the grinding liquid to the first main surface W1 and the second main surface Supply ratio adjustment information indicating how the nanotopography changes when the ratio of the grinding liquid supply amount to W2 is adjusted is stored. For example, as in the result obtained in Experiment 3, the supply ratio adjustment information that the recess amount of the first main surface W1 becomes smaller as the ratio of the supply amount to the first main surface W1 becomes higher is stored. deep. At this time, the material and size of the wafer W, the target thickness after grinding, or the total amount of the grinding liquid supplied, and further, the relationship between the rotation direction of the wafer W and the first and second grinding wheels 23, 24. It is preferable to store the supply ratio adjustment information having different contents. The supply ratio adjustment information may be created based on an experimental result using the double-sided grinding machine 1 or may be created by simulation.
Then, the control means 5 may adjust the ratio of the supply amount such that the nanotopography of the second wafer W _p approaches 0 based on the nanotopography of the first wafer W _t and the supply ratio adjustment information. ..

DESCRIPTION OF SYMBOLS 1... Double-head grinding device, 2... Grinding means, 3... Differential transformer type displacement gauge (thickness measuring means), 23, 24... 1st and 2nd grinding wheels, 23B, 24B... Grinding stone, 33... Contact, W ... wafer (object to be ground), W _t ... first wafer (first object to be ground), W _p ... first wafer (second object to be ground), W1 ... first main surface (on the other hand Main surface), W2... second main surface (other main surface).

Claims (3)

The object to be ground is ground by rotating the object to be ground and supplying a grinding liquid to both main surfaces of the object to be ground, and bringing a grindstone of a grinding wheel into contact with both main surfaces of the object to be ground. Using a double-sided grinder including a grinding means and a thickness measuring means for measuring the thickness of the object to be ground, the thickness of the object to be ground is a predetermined thickness based on the measurement result of the thickness measuring means. It is a double-sided grinding method that grinds until
A first grinding step of performing grinding until the thickness of the first object to be ground reaches the predetermined thickness while supplying a predetermined amount of grinding liquid to both main surfaces of the first object to be ground;
A nanotopography measuring step of measuring the nanotopography of the first object to be ground;
Based on the measurement result of the nanotopography measurement step, the grinding conditions are adjusted so that the nanotopography of the second object to be ground approaches 0, and the thickness of the second object to be ground becomes the predetermined thickness. And a second grinding step of grinding until
In the second grinding step, while maintaining the total amount of the grinding fluid supplied in the first grinding step, the amount of the grinding fluid supplied to one main surface of the second object to be ground and the other main surface thereof. A double-sided grinding method, characterized in that the second object to be ground is ground by adjusting the ratio with the supply amount of the grinding liquid. The double-sided grinding method according to claim 1,
As the thickness measuring means, a pair of contacts that respectively come into contact with both main surfaces of the object to be ground, and the thickness of the object to be ground by outputting a signal corresponding to the position of the pair of contacts. A double-headed grinding method characterized by using a differential transformer type displacement meter for measuring the. The double-sided grinding method according to claim 1 or 2,
The second grinding step is based on the measurement result of the nanotopography measuring step of the first object to be ground, and is used to determine the main side of the second object to be ground on the concave side of the first object to be ground. A double-sided grinding method, wherein the ratio is adjusted so that the amount of the grinding liquid supplied to the surface is larger than the amount of the grinding liquid supplied to the other main surface.

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