KR20170081943A - Wafer polishing apparatus and method - Google Patents

Abstract

The wafer polishing apparatus according to the embodiment includes a lower polishing unit; An estimating unit arranged on the lower half and rotating; A carrier for receiving a wafer and disposed on the lower half; And a sensor unit that rotates together with the assumed wafer, irradiates light to a wafer accommodated in the carrier, detects light reflected by the wafer, and outputs detection data according to the detected result, wherein the sensor unit And a thickness measurement sensor for outputting data, wherein an alignment section for aligning the lower surface of the thickness measurement sensor in a horizontal state is disposed on the upper surface of the supposition section.

Description

[0001] WASHING POLARIZING APPARATUS AND METHOD [0002]

Embodiments relate to a wafer polishing apparatus and method.

Generally, a silicon single crystal ingot is grown by the Czochralski method (CZ method), and the obtained silicon ingot is sliced using a wire saw to produce a sliced wafer. Then, the sliced wafer is subjected to lapping and etching etching, cleaning and polishing processes can be performed to obtain a silicon wafer.

In the polishing step, both surfaces of a sliced wafer are polished by using a wafer polishing apparatus to obtain a planarized silicon wafer.

The polishing rate of the wafer may be changed each time the polishing process is performed by the deterioration of the processing tool or the carrier such as a polishing cloth or a carrier. Therefore, when the polishing is performed by fixing the polishing time, the thickness of the wafer after polishing may be changed as the polishing rate varies depending on the above-described causes. It is necessary to adjust the polishing speed and the like while measuring the thickness of the wafer during polishing.

Embodiments provide a wafer polishing apparatus and a wafer polishing method that can accurately measure the thickness of a wafer to be polished and can improve the polishing quality of the wafer.

The wafer polishing apparatus according to the embodiment includes a lower polishing unit; An estimating unit arranged on the lower half and rotating; A carrier for receiving a wafer and disposed on the lower half; And a sensor unit that rotates together with the assumed wafer, irradiates light to a wafer accommodated in the carrier, detects light reflected by the wafer, and outputs detection data according to the detected result, wherein the sensor unit And a thickness measurement sensor for outputting data, wherein an alignment section for aligning the lower surface of the thickness measurement sensor in a horizontal state is disposed on the upper surface of the supposition section.

For example, the assumption unit may include one through hole through which light emitted from the sensor unit passes.

For example, the thickness measuring sensor may include an optical unit for irradiating light and a photodetector for detecting light reflected from the wafer, and the aligning unit may adjust a distance between a lower edge of the thickness measuring sensor and an upper surface of the supposition half So that the light irradiated from the optical unit can be vertically aimed at the center of the through hole by aligning the lower surface of the thickness measurement sensor in a horizontal state.

For example, the polishing apparatus may further include a control section for calculating the thickness of the polished wafer based on the detection data.

For example, the sensor unit may include a cable for transmitting the detection data to the control unit; And a rotary connector connected to the cable.

For example, the sensor unit may be fixed to the upper surface of the supposition plate.

For example, the sensor may further include a load corrector fixed to a region opposite to a region of the upper surface of the hypothetical unit to which the sensor unit is fixed, wherein the weight of the load corrector may be the same as the weight of the sensor unit.

For example, the slurry supply apparatus may further include a slurry supply unit disposed on the supposition half, supplying the slurry to the supposition unit, and rotating together with the supposition unit.

For example, it may further include a light transmitting film disposed on an inner wall of the through hole and covering the lower end of the through hole.

For example, the control unit may perform the polishing process on the wafer based on the shape information of the polished wafer acquired for each predetermined interval, the difference between the maximum value and the minimum value of the wafer thickness profile, and the integrated value of the wafer thickness profile Whether you can decide,

For example, the control unit may terminate the polishing of the wafer at a point where the difference between the maximum value and the minimum value of the wafer thickness profile becomes minimum and the integral value of the wafer thickness profile is zero.

For example, the control unit may calculate a distance between the center of the carrier, the coordinates of the central movement locus of the wafer received in the carrier, and the distance from the center of the wafer to the thickness measurement positions of the wafer by the sensor unit The shape information of the polished wafer can be obtained.

A wafer polishing method according to another embodiment is a method for polishing a wafer loaded on at least one carrier disposed on the lower half using a wafer polishing apparatus including a lower polishing chamber, an upper polishing chamber and a sensor portion rotating together with the upper polishing chamber, Measuring the thickness of the wafer to be polished using the sensor portion while starting polishing; Determining whether the thickness of the wafer to be polished has reached a predetermined reference thickness; Acquiring shape information of the wafer for a predetermined interval when the thickness of the wafer to be polished reaches the reference thickness; Calculating a maximum value, a minimum value, and an integral value of the wafer thickness profile using the obtained shape information of the wafer; And determining whether the polishing of the wafer is completed based on the maximum value and the minimum value of the calculated thickness profile of the wafer and the integral value.

For example, the step of acquiring the shape information of the wafer may include measuring the thicknesses of the wafer to be polished at random thickness measurement positions for the predetermined interval; And obtaining a maximum value and a minimum value of the wafer thickness in a radial direction of the wafer and a thickness profile of the wafer based on the measured thicknesses of the wafer to be polished.

For example, the step of acquiring shape information of the wafer may include deriving a moving average value of a difference between a maximum value and a minimum value of the wafer thickness and a profile integral value of the wafer thickness while the wafer is being polished .

For example, in the step of determining whether or not the polishing of the wafer is finished, polishing of the wafer may be terminated at a point where the moving average value of the difference between the maximum value and the minimum value becomes minimum and becomes 0 out of the moving average value of the profile integrated value .

The embodiment can accurately measure the thickness of the wafer to be polished, thereby improving the polishing quality of the wafer.

1 shows a cross-sectional view of a wafer polishing apparatus according to an embodiment.
2 shows the amount of data acquired by the fixed thickness measuring sensor and the rotating thickness measuring sensor.
Fig. 3 is an enlarged view of a part of the supposition quadrant formed with the through hole according to the embodiment.
Figure 4 shows the difference in wafer shape due to gaps and gaps due to the difference in thickness between the carrier and the wafer.
5 is a flowchart showing a wafer polishing method according to an embodiment.
Fig. 6 shows a change in wafer shape with polishing time.
Fig. 7A shows the movement locus of the center of the carrier during wafer polishing.
Fig. 7B shows the movement locus of the center of the wafer mounted on the carrier shown in Fig. 7A.
8 shows the thickness measurement positions of the wafer measured using the thickness measurement sensor of the embodiment.
9A and 9B are graphs showing the maximum and minimum values of the wafer thickness profile according to the polishing time, and the wafer thickness profile integrated values.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other features and advantages of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: FIG. In the description of the embodiments, it is to be understood that each layer (film), region, pattern or structure may be referred to as being "on" or "under" a substrate, each layer It is to be understood that the terms " on "and " under" include both " directly "or" indirectly " do. In addition, the criteria for the top / bottom or bottom / bottom of each layer will be described with reference to the drawings.

In the drawings, dimensions are exaggerated, omitted, or schematically illustrated for convenience and clarity of illustration. Also, the size of each component does not entirely reflect the actual size. The same reference numerals denote the same elements throughout the description of the drawings.

1 shows a cross-sectional view of a wafer polishing apparatus 100 according to an embodiment.

1, the wafer polishing apparatus 100 includes a lower polishing pad 110, a first polishing pad 112, a lower polishing half polishing pad 115, an upper polishing pad 120, a second polishing pad 122, a sun gear a sun gear 132, an internal gear 134, at least one carrier 140, a slurry supply unit 150, an anticlockwise rotation unit 160, a sensor unit 170, a control unit 180, And an alignment unit 190.

The lower substrate 110 may be in the form of an annular disc having a hollow shape and supporting the wafer W loaded or received in at least one of the carriers 140. A first polishing pad 112 for polishing a wafer may be mounted on or attached to the upper surface of the lower polishing plate 110.

The lower half rotating part 115 is disposed below the lower half 110 and rotates the lower half 110.

The lower half rotating part 115 may include a first rotating shaft for rotating the lower half 110 and a first rotating shaft may rotate the lower half 110 clockwise or counterclockwise.

For example, the first rotation shaft can be rotated by the rotation of the driving motor (not shown), and the lower rotation unit 110 can be rotated counterclockwise or clockwise together with the first rotation shaft.

The hypothesis unit 120 may be disposed on the lower stage 110 such that the lower surface of the hypothesis unit 110 faces the upper surface of the lower unit 110 and may be an annular disc having a hollow shape. A second polishing pad 122 for polishing the wafer may be mounted or attached to the lower surface of the supposition plate 120.

The assumption unit 120 may have one through hole 125 through which the light emitted from the sensor unit 170, which will be described later, passes. For example, the through hole 125 may penetrate the supporter 120 and the second polishing pad 122.

The sensor unit 170 includes a thickness measuring sensor 172 for outputting detection data. The thickness measuring sensor 172 is disposed on the upper surface of the thickness measuring sensor 172, (190).

Fig. 3 is an enlarged view of a part of the supposition quadrant formed with the through hole according to the embodiment.

Referring to FIG. 3, a light transmitting film 310 for transmitting light may be disposed in the through hole 125 of the anticipatory unit 120. The light transmitting film 310 may be disposed on the inner wall of the through hole 125 and may cover the lower end of the through hole 125. [

For example, one end of the light transmitting film 310 may be fixed to the upper surface of the light guide plate 120 adjacent to the through hole 125 by the fasteners 312 and 314. For example, fasteners 312 and 314 may be screws, but are not limited thereto.

The light transmitting film 310 may be attached to the inner wall of the through hole 125 using a double-sided tape or an adhesive or the like and the other end of the light transmitting film 310 may block the bottom of the through hole 125. The light transmitting film 310 may be a transparent plastic, for example, transparent PVC, but is not limited thereto.

Referring to FIG. 1, the slurry supply unit 150 is disposed on the supposition plate 120 and supplies the slurry to the supposition plate 120. The slurry supply unit 150 may be connected to the upper surface of the supposition plate 120 and rotate together with the supposition plate 120. The slurry may be supplied to at least one carrier (140) through a slurry supply pipe (not shown) through which the slurry supplied from the slurry supply unit (150) As shown in FIG.

The inferred rotary part 160 can rotate the assumed part 120 and move the assumed part 120 up and down.

The assumed semi-rotary part 160 may be connected to the slurry supply part 150 and may include a second rotary shaft for rotating the rotary table 120.

For example, the second rotating shaft may be connected to the upper surface of the slurry supplying unit 150, and the slurry supplying unit 150 and the receiving unit 120 may be rotated clockwise or counterclockwise together. For example, the second rotary shaft may be connected to a driving motor (not shown), and the second rotary shaft may be rotated by the rotation of the driving motor. In addition, the second rotary shaft may be rotated clockwise or counterclockwise It can rotate.

The assumed semi-rotary part 160 can adjust the load of the imaginary part 110 applied to the wafer W loaded on at least one carrier 140 by moving the imaginary part 120 up and down.

For example, the second rotary shaft may be connected to a pneumatic or hydraulic cylinder (not shown), and may be connected to a wafer W loaded on at least one carrier 140 by a pneumatic or hydraulic cylinder The load can be adjusted.

The sun gear 132 may be disposed in the hollow of the bottom plate 110 and may be in the form of a pin gear having a plurality of first pins.

The internal gear 134 may be positioned around the edge of the lower half 110. For example, the internal gear 134 may have the shape of an annular disc surrounding the outer peripheral surface of the lower edge of the lower half 110. The internal gear 134 may be in the form of a pin gear including a plurality of second pins.

At least one carrier 140 is disposed on the top surface of the bottom plate 110 and can receive or load the wafer W to be polished. For example, at least one carrier 140 may be disposed between the first polishing pad 112 on the bottom half 110 and the second polishing pad 122 on the bottom half 120.

The at least one carrier 140 includes a carrier body having a wafer mounting hole (not shown) for receiving the wafer W and at least one slurry hole spaced apart from the wafer mounting hole through which the slurry passes, And a gear provided. The at least one carrier 140 may be epoxy glass, SUS, urethane, ceramic, or a polymer material.

The carrier body may be of a disc shape, but is not limited thereto. The gear formed on the outer peripheral surface of the edge of the carrier 140 may be engaged with the first pins of the sun gear 132 and the second pins of the internal gear 134. At least one carrier 140 may be a sun gear 132 and the internal gear 134 so as to perform rotational motion during the polishing process.

The sensor unit 170 is fixed to the slurry supply unit 150 and rotates together with the slurry supply unit 150 and the slurry supply unit 120. The sensor unit 170 is connected to the at least one carrier 140 , And detects the light reflected by the wafer W, and outputs the detection data WD according to the detected result.

For example, the light emitted from the sensor unit 170 may be laser, but is not limited thereto.

The sensor portion 170 includes a thickness measuring sensor 172, a cable 174, and a rotary connector 176. [

The thickness measuring sensor 172 rotates together with the slurry supply unit 150 and the supporter 120 to irradiate the wafer W with light through the through hole 125 and to reflect the light reflected by the wafer W It is possible to output the detection data DW according to the detected result.

For example, the thickness measurement sensor 172 may include an optical unit for irradiating light (e.g., laser) and a photodetector for detecting the laser reflected from the wafer W. [

1 and 3, the aligning unit 190 may be disposed around the through hole 125 formed in the upper surface of the supporter 120, and may be disposed to face the lower surface of the thickness measurement sensor 172 .

The center of the thickness measuring sensor 172 may be aligned with the center of the through hole 125. The aligning unit 190 may measure the distance between the lower edge of the thickness measuring sensor 172 and the upper surface of the upper half 120 And the lower surface of the thickness measurement sensor 172 is aligned in a horizontal state so that light irradiated from the optical unit can be vertically aimed at the center of the through hole.

The light (e.g., laser) irradiated from the optical unit for accurate thickness measurement can be aimed to be aligned in the center of the through hole 125.

Since the light irradiated from the optical unit is vertically collimated through the through hole 125 to aim the surface of the wafer placed on the carrier 140, The lower surface of the thickness measuring sensor 172 can be maintained in a horizontal state.

The alignment unit 190 includes a plurality of distance measurement sensors around the through hole 125 of the detection unit 120 to measure the distance between the upper surface of the detection unit 120 and the lower edge of the thickness measurement sensor 172 .

The distance measured by each distance measuring sensor may be transmitted to a first controller (not shown), and the distance measured by each distance measuring sensor may be compared to align the thickness measuring sensor 172.

For example, the aligning unit 190 changes the position of the load correcting unit 155 to move a center of the thickness measuring sensor 172 so that the lower surface of the thickness measuring sensor 172 is horizontal, 172).

The thickness measuring sensor 172 can detect the light reflected by the surface of the wafer W and the light reflected by the wafer W and detects the detection data WD relating to the thickness of the wafer according to the detected result Can be output.

The cable 174 connects the thickness measurement sensor 172 and the control unit 180 via the rotary connector 176 and connects the detection data WD related to the thickness of the wafer detected by the photodetector of the thickness measurement sensor 172, Is transmitted to the control unit 180 through the cable 174. [

The rotary connector 176 is connected to the cable 174 and can serve to prevent the cable 174 from twisting when the thickness measuring sensor 172 rotates. The rotary connector 176 may be embodied in a bearing structure and may be configured to cause the cable 174 to rotate with the counterweight 120 to prevent interference between the cable 174 and the thickness measurement sensor 172 .

2 shows the amount of data acquired by the fixed thickness measuring sensor and the rotating thickness measuring sensor.

The fixed thickness measuring sensor is fixedly arranged irrespective of rotation of the anticipation half, and a plurality of through holes are formed in the anticipation half. When the wafer is rotated at the time of polishing, the fixed thickness sensor can detect the light irradiated and reflected by the laser through the plurality of through holes formed in the rotating wafer.

Referring to FIG. 2, in the case of the fixed thickness measurement sensor, the positions P1 to P5 at which the detection data can be obtained may correspond to the through holes formed at a distance from the assumed half.

On the other hand, as in the embodiment, the rotatable thickness measurement sensor 172 rotating together with the supposition unit 120 may be capable of obtaining substantially continuous detection data through one through hole 125. [

The control unit 180 calculates the thickness of the wafer based on the detection data WD relating to the thickness of the wafer transferred through the cable 174. [

For example, the controller 180 can measure the thickness of the wafer W by using the phase difference between the light reflected from the surface of the wafer W and the light reflected through the wafer W. [

Since the thickness measurement sensor 172 rotates simultaneously with the imaginary plane 120, continuous detection data regarding the thickness of the wafer can be obtained through one through hole 125, which makes it possible to obtain accurate wafer thickness Measurement is possible.

The load correcting unit 155 may be fixed to a region opposite to one region of the slurry supplying unit 150 to which the thickness measuring sensor 172 is fixed. The weight of the load correcting unit 155 may be equal to the weight of the thickness measuring sensor 172. [

The load correcting unit 155 can prevent the load of the imaginary casting unit 120 from being biased by the thickness measuring sensor 172 on either side.

The wafer polishing apparatus 100 according to the embodiment has a rotatable thickness measuring sensor 172 that rotates together with the supposition plate 120 and a single through hole 125 is formed by the rotatable thickness measurement sensor 172 Since the continuous detection data can be obtained through the polishing process, the thickness of the wafer to be polished can be accurately measured during the polishing process.

The control unit 180 can measure the thickness accurately during the double-side polishing process using the detection data relating to the thickness of the wafer provided from the sensor unit 170 of the wafer polishing apparatus 100 according to the embodiment, Lt; RTI ID = 0.0 > GBIR < / RTI >

First, the factors affecting the shape of the wafer in the polishing process will be described.

The shape of the wafer being polished in the double-side polishing process can be influenced by the gap due to the difference in thickness between the carrier and the wafer.

4 shows a difference in wafer shape according to a gap and a gap due to the difference in thickness between the carrier and the wafer.

Referring to FIG. 4, the larger the gap due to the difference in thickness between the carrier and the wafer, the more the wafer may have a convex shape. On the other hand, as the gap due to the difference in thickness between the carrier and the wafer is smaller, the shape of the wafer may change to a concave shape.

For example, when the gap is 6 mm or more, the shape of the polished wafer may be convex, and when the gap is less than 6 mm, the shape of the polished wafer may have a concave shape at least partially.

In addition, various factors such as wear of the carrier, change of the surface of the polishing pad, change of the physical properties of the slurry and the like may also affect the shape of the wafer to be polished as the polishing progresses. The scattering of GBIR can be significant by the above factors.

Even if the shape of the wafer to be polished is affected by the above factors, the GBIR according to the thickness of the wafer to be polished can be measured and the thickness of the polished wafer having the optimum GBIR can be obtained based on the measured result.

In order to reduce the scattering of GBIR due to factors influencing the shape of the wafer being polished as the polishing progresses, the optimum polishing thickness of the wafer must be changed to suit the situation.

The double-side polishing method according to the embodiment uses the wafer polishing apparatus 100 shown in FIG. 1 capable of precisely controlling the polishing thickness to monitor the shape change of the wafer in the polishing process, and has the lowest GBIR quality Lt; / RTI > finishes the double-side polishing in the thickness of the polished wafer.

The control unit 180 determines whether to perform the polishing process on the wafer based on the shape information of the polished wafer acquired for each predetermined interval, the difference between the maximum value and the minimum value of the wafer thickness profile, and the integrated value of the wafer thickness profile .

Then, the control unit 180 can finish polishing the wafer at a point where the difference between the maximum value and the minimum value of the wafer thickness profile is the smallest and the integral value of the wafer thickness profile is zero.

Based on the coordinates of the center movement locus of the carrier, the coordinates of the center movement locus of the wafer received in the carrier, and the distances from the center of the wafer to the wafer thickness measurement positions by the sensor unit, The shape information of the wafer can be obtained.

Fig. 5 is a flow chart showing a double-side polishing method according to an embodiment, and Fig. 6 shows a change in wafer shape according to polishing time.

5 and 6, on the basis of the detection data provided through the thickness measurement sensor 170 of the wafer polishing apparatus 100, the control unit 180 controls at least one carrier (not shown) The wafer W loaded on the wafer 140 is started to be double-sided and the thickness of the wafer to be polished is measured (S110). For example, the thickness of the wafer measured in step S110 may be an average thickness of the wafer.

According to Fig. 6, the thickness of the wafer decreases with the polishing time. In the case of a wafer having a diameter of 300 mm, the center of the wafer is convex upward at the beginning of polishing of the wafer and the average thickness of the wafer is 773 m When the wafer has the most flat shape and the average thickness of the wafer is 773 mu m or less, the center of the wafer is concave.

The thickness measurement sensor 172 of the wafer polishing apparatus 100 according to the embodiment can be used to measure the thicknesses of wafers for a predetermined interval and obtain the thickness profile of the wafers in the radial direction according to the measured results .

For example, the control unit 180 controls the thickness measuring sensor 172 to measure the coordinates of the center movement locus of the carrier 140, the coordinates of the center locus of the wafer W received in the carrier 140, and the center of the wafer W The shape information of the polished wafer can be obtained based on the distances (e.g., R1 and R2) up to the wafer thickness measurement positions by the wafer.

The center locus of the carrier 140 can be controlled by the sun gear 132 and the internal gear 134 and the locus of movement of the center of the wafer to be polished can be controlled by controlling the center locus of movement of the carrier 140 And the movement locus of the center of the wafer to be polished can be estimated or calculated.

The movement locus of the center of the wafer W mounted on the carrier 140 can be estimated through the control of the center locus of movement of the carrier 140 by the sun gear 132 and the internal gear 134. [

7A shows the movement locus of the center 902 of the carrier during double-side polishing.

The coordinates of the movement trajectory of the carrier and wafer may be an XY coordinate system and the origin 901 of the XY coordinate system of the movement trajectory of the carrier and wafer may be the coordinate (X0, Y0) corresponding to the center of the carrier drive, .

Referring to FIG. 7A, the movement locus Xc, Yc of the center 902 of the carrier can be calculated by the following equations (1) to (3).

Vc may be the rotational speed of the carrier (e.g., RPM), t may be time (e.g., second), and Rc may be the distance from the origin 901 to the center 902 of the carrier.

Fig. 7B shows the movement locus of the center 903 of the wafer mounted on the carrier shown in Fig. 7A.

Referring to FIG. 7B, the movement locus Xw, Yw of the center 903 of the wafer can be calculated by Equations (4) to (6).

Rw may be the distance from the center 902 of the carrier to the center 903 of the wafer. Vc and t may be the same as those described in Fig. 7A.

8 shows the wafer thickness measurement positions 904-1 and 904-2 measured using the thickness measurement sensor 172 of the embodiment. Although only two thickness measurement positions 904-1 and 904-2 are shown in FIG. 8, substantially the thickness measurement sensor 172 measures the thicknesses of the wafers at a plurality of random thickness measurement positions for a predetermined interval .

Here, the thickness measuring position may be the position of one region of the wafer through which the thickness is measured through the through hole 125. [

8, the coordinates (Xc, Yc) of the center movement locus of the carrier and the coordinates (Xw, Yw) of the movement locus of the center 903 of the wafer are used to determine the wafer thickness The distances R1 and R2 to the measurement positions 904-1 and 904-2 can be calculated.

For example, the coordinates (Xw, Yw) of the central movement locus of the wafer can be obtained using the coordinates (Xc, Yc) of the central locus of movement of the carrier and the coordinates (Xw, Yw) 904-2 from the center 903 of the wafer by using the coordinates (X1, Y1), (X2, Y2) of the positions 904-1, 904-2, Can be calculated.

The wafer thickness is measured randomly by the thickness measurement sensor 172 but the distances from the center 903 of the wafer to the wafer thickness measurement positions 904-1 and 904-2 ), It is possible to obtain the thickness profile of the wafer in the radial direction of the wafer, thereby obtaining the shape information of the wafer. For example, the radial direction of the wafer may be the direction from the center of the wafer to the edge of the wafer.

The predetermined reference thickness in the step S120 of determining whether the thickness of the wafer to be polished has reached a preset reference thickness may be the maximum thickness of the polishing process control reference, and may be, for example, 780 탆 to 800 탆.

The shape information of the wafer can be obtained for a predetermined period from the time when the thickness of the polished wafer reaches the reference thickness, wherein the predetermined period may be 15 to 60 seconds.

When the thickness of the wafer to be polished reaches the reference thickness, the step (S130) of obtaining the shape information of the wafer for a preset interval measures the thicknesses of the wafer to be polished at a plurality of random thickness measuring positions for a predetermined interval (S140) obtaining a maximum value and a minimum value of the wafer thickness in the radial direction of the wafer, and a thickness profile of the wafer, based on the measured thicknesses of the wafer being polished .

9A and 9B are graphs showing the maximum and minimum values of the wafer thickness profile according to the polishing time, and the wafer thickness profile integrated values.

9A shows the difference between the maximum value and the minimum value of the wafer thickness profile according to the polishing time, and the curve located downward shows the integrated value of the wafer thickness profile according to the polishing time. Noise data due to errors occur on each curve as shown in A on the graph.

Step S130 of obtaining the shape information of the wafer to remove the noise includes calculating a difference between the maximum value and the minimum value of the wafer thickness and a moving average value of the profile integrated value of the wafer thickness while the wafer is being polished (S150).

From the step (S150) of deriving a moving average value of the difference between the maximum value and the minimum value of the wafer thickness and the profile integrated value of the wafer thickness, the maximum value and the minimum value of the noise-removed wafer thickness profile and the wafer thickness profile integration Value can be derived.

In step S160 of determining whether wafer polishing is to be terminated, wafer polishing can be terminated (S170) at a point where the moving average value of the difference between the maximum value and the minimum value becomes the minimum and the moving average value of the profile integrated value becomes zero .

GBIR (Global Backside Reference Indicated Reading) shows the overall flatness of a wafer. In the double-side polishing method according to the embodiment, the shape information of the wafer is acquired every predetermined interval using a thickness measuring sensor capable of accurately measuring the thickness, It is possible to obtain the polishing thickness of the wafer having the lowest GBIR based on the obtained shape information, thereby improving the polishing quality of the wafer.

The features, structures, effects and the like described in the embodiments are included in at least one embodiment of the present invention and are not necessarily limited to one embodiment. Further, the features, structures, effects, and the like illustrated in the embodiments can be combined and modified by other persons having ordinary skill in the art to which the embodiments belong. Therefore, it should be understood that the present invention is not limited to these combinations and modifications.

110: Lower polishing pad 112: First polishing pad
115: Lower half counter-rotating part 120:
122: second polishing pad 132: sun gear
134: Internal gear 140: Carrier
150: Slurry supply unit 160:
170: sensor unit 180: control unit

Claims (16)

Ha Jung - van;
An estimating unit arranged on the lower half and rotating;
A carrier for receiving a wafer and disposed on the lower half; And
And a sensor unit that rotates together with the assumed wafer, irradiates light to a wafer accommodated in the carrier, detects light reflected by the wafer, and outputs detection data according to the detected result,
Wherein the sensor unit includes a thickness measurement sensor for outputting the detection data, and an alignment unit for horizontally aligning the lower surface of the thickness measurement sensor is disposed on the upper surface of the supposition unit. The method according to claim 1,
Wherein said supposition half has one through hole through which light irradiated from said sensor unit passes. 3. The method of claim 2,
Wherein the thickness measurement sensor includes an optical unit for irradiating light and a photodetector for detecting light reflected from the wafer,
Wherein the alignment unit measures the distance between the lower edge of the thickness measurement sensor and the upper surface of the supposition half and aligns the lower surface of the thickness measurement sensor in a horizontal state so that the light irradiated from the optical unit is perpendicular to the center of the through hole A wafer polishing apparatus for aiming. The method according to claim 1,
And a control unit for calculating a thickness of the polished wafer based on the detected data. 5. The apparatus according to claim 4,
A cable for transmitting the detection data to the control unit; And
Further comprising a rotary connector connected to the cable. The method according to claim 1,
And the sensor unit is fixed to the upper surface of the supposition unit. The method according to claim 6,
Further comprising: a load correcting unit fixed to an area opposite to one area of the upper surface of the supposition unit on which the sensor unit is fixed, wherein the weight of the load correcting unit is equal to the weight of the sensor unit. The method according to claim 1,
And a slurry supply unit arranged on the supposition half and supplying the slurry to the supposition unit and rotating together with the supposition unit. 3. The method of claim 2,
And a light transmitting film disposed on an inner wall of the through hole and covering the lower end of the through hole. 5. The apparatus of claim 4,
And determines whether to perform the polishing process on the wafer based on the shape information of the polished wafer acquired for each predetermined section, the difference between the maximum value and the minimum value of the wafer thickness profile, and the integrated value of the wafer thickness profile. 11. The apparatus according to claim 10,
Wherein the difference between the maximum value and the minimum value of the wafer thickness profile is minimized and the polishing for the wafer is terminated at a point where the integral value of the wafer thickness profile is zero. 11. The apparatus according to claim 10,
Based on the coordinates of the center movement locus of the carrier, the coordinates of the center movement locus of the wafer received in the carrier, and the distances from the center of the wafer to the thickness measurement positions of the wafer by the sensor unit, The shape information of the wafer is obtained. Side polishing of a wafer loaded on at least one carrier arranged on the lower half is started by using a wafer polishing apparatus including a lower polishing chamber, an upper polishing chamber and a sensor portion rotating together with the above-mentioned chamber, Measuring the thickness of the wafer to be polished;
Determining whether the thickness of the wafer to be polished has reached a predetermined reference thickness;
Acquiring shape information of the wafer for a predetermined interval when the thickness of the wafer to be polished reaches the reference thickness;
Calculating a maximum value, a minimum value, and an integral value of the wafer thickness profile using the obtained shape information of the wafer; And
Determining whether or not the polishing of the wafer is completed based on the calculated maximum value and minimum value of the thickness profile of the wafer and the integral value. 14. The method of claim 13, wherein obtaining the shape information of the wafer comprises:
Measuring the thicknesses of the wafer to be polished at random thickness measurement positions for the predetermined interval; And
And obtaining a maximum value and a minimum value of the wafer thickness in the radial direction of the wafer and a thickness profile of the wafer based on the measured thicknesses of the wafer being polished. 14. The method of claim 13, wherein obtaining the shape information of the wafer comprises:
Further comprising deriving a difference between a maximum value and a minimum value of the wafer thickness and a moving average value of the profile integral of the wafer thickness while the wafer is being polished. 14. The method of claim 13, wherein determining whether to terminate wafer polishing comprises:
And polishing the wafer at a point where the moving average value of the difference between the maximum value and the minimum value becomes minimum and the moving average value of the profile integrated value becomes zero.

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