Wafer double-side polishing equipment and evaluation method thereof

Abstract

Disclosed is a wafer bilateral polishing apparatus. The wafer double-side polishing apparatus includes an upper plate and a lower plate facing each other, polishing pads disposed at a lower portion of the upper plate and at an upper portion of the lower plate, respectively, a first gear disposed at a central region of an upper surface of the lower plate, a second gear disposed at a peripheral region of the upper surface of the lower plate, and a carrier disposed between the polishing pads while engaging between the first gear and the second gear. The upper plate includes a plurality of paste supply holes extending in a vertical direction. Each of the carriers includes at least one wafer receiving hole. The sum of the cross-sectional areas of the wafer accommodating holes of the carrier is 32% to 34% of the cross-sectional area of the lower plate.

Description

[0001] This application claims the benefit of Korean Patent Application No. 10-2023-0160776, filed on September 27, 2023, which is hereby incorporated by reference as if fully set forth herein. Background Art Technical Field

[0002] The present disclosure relates to a wafer double-side polishing device and an evaluation method thereof, and more particularly to a wafer double-side polishing device and an evaluation method thereof that can ensure high flatness of the wafer after the wafer is polished. Related technical discussions

[0003] The manufacture of a typical silicon wafer includes an ingot growing process of producing an ingot, a slicing process of slicing the ingot to obtain wafers having a thin disk shape, a grinding process of removing damage remaining at the wafer due to slicing caused by mechanical processing, a polishing process of polishing the wafer to have a mirror surface, and a cleaning process of mirror-polishing the polished wafer and removing abrasives or foreign matter attached to the wafer.

[0004] The polishing process can be divided into double-side polishing, that is, polishing the wafer with a small thickness to remove surface defects and make the wafer have better flatness, and final polishing, that is, fine polishing the wafer with a thickness of about 1μm to reduce the roughness so that the wafer has a mirror surface.

[0005] The wafer double-side polishing apparatus includes a lower plate with a pad attached to an upper surface thereof, an upper plate with a pad attached to a lower surface thereof, and a carrier mounted between the upper and lower plates and configured to support a wafer mounted thereon.

[0006] The wafer is loaded in a hole formed in the carrier. The upper plate moves downward, thereby applying pressure to the wafer. In this state, the upper plate and the lower plate rotate at a predetermined rotation ratio under the condition of supplying slurry, so that chemical-mechanical polishing can be performed.

[0007] The flatness of the polished wafer may vary depending on the type and distribution of the supplied slurry, the type of pad, and the like.

[0008] In addition, the supply and distribution of the slurry may affect the shape change of the wafer and the flatness of the wafer. For this reason, when the slurry supply is uneven, the sedimentation of the polishing byproducts may increase in the thin area of ​​the slurry layer, thereby causing uneven polishing of the wafer by the polishing pad. As a result, a wafer with high flatness may not be obtained.

[0009] In order to solve such a problem, a solution of supplying slurry at the lower plate can be considered. In this case, the slurry is pushed upward by a pressurizing method, so the wafer being polished may be pushed upward, thereby causing uneven polishing of the wafer. Summary of the invention

[0010] Accordingly, the present disclosure is directed to a wafer double-side polishing apparatus and an evaluation method thereof that substantially obviates one or more problems due to limitations and disadvantages of the related art.

[0011] The object of the present disclosure is to provide a wafer double-side polishing apparatus and an evaluation method thereof that can ensure high flatness of the wafer after wafer polishing.

[0012] The objects of the present disclosure are not limited to the above objects, and those skilled in the art will more clearly understand other objects of the present disclosure that have not been described from the following detailed description.

[0013] To achieve these objectives and other advantages and in accordance with the purposes of the present disclosure, as embodied and generally described herein, a wafer double-sided polishing apparatus includes an upper plate and a lower plate facing each other, polishing pads arranged at a lower portion of the upper plate and an upper portion of the lower plate, respectively, a first gear arranged in a central area of ​​an upper surface of the lower plate and a second gear arranged in a peripheral area of ​​an upper surface of the lower plate, and a carrier arranged between the polishing pads and simultaneously engaged between the first gear and the second gear, wherein the upper plate includes a plurality of slurry supply holes extending in a vertical direction, wherein each of the carriers includes at least one wafer accommodating hole, and wherein the sum of the cross-sectional areas of the wafer accommodating holes of the carriers is 32% to 34% of the cross-sectional area of ​​the lower plate.

[0014] The carriers may have the same shape, and the at least one wafer receiving hole of each carrier includes three wafer receiving holes. The carriers may include five carriers engaged between the first gear and the second gear.

[0015] The carriers may have the same shape, and the at least one wafer receiving hole of each carrier includes four wafer receiving holes. The carrier may include four carriers engaged between the first gear and the second gear.

[0016] The slurry supplied to the slurry supply hole may include silicon dioxide particles having a size of 40 to 100 nanometers.

[0017] The pH of the slurry may be 11 or greater.

[0018] The particle concentration of the slurry may be 1% to 1.5%.

[0019] Each of the polishing pads may have a hardness of 83 to 93 HRC.

[0020] Each of the polishing pads may have a compression degree of 0.7% to 3.1%.

[0021] The wafers can be respectively accommodated in the wafer accommodation holes of the carrier, and the lower plate and the upper plate can pass 100 to 160 g / cm 2 The force is used to apply pressure.

[0022] In another aspect of the present disclosure, a wafer double-side polishing equipment evaluation method includes: preparing a wafer double-side polishing equipment, the wafer double-side polishing equipment including an upper plate and a lower plate facing each other, polishing pads arranged at a lower portion of the upper plate and an upper portion of the lower plate, respectively, a first gear arranged in a central area of ​​an upper surface of the lower plate, a second gear arranged in a peripheral area of ​​an upper surface of the lower plate, and a carrier arranged between the polishing pads and engaged between the first gear and the second gear, the upper plate including a plurality of slurry supply holes extending in a vertical direction, each of the carriers including at least one wafer accommodating hole; accommodating wafers in the wafer accommodating holes of the carriers, respectively, supplying slurry through the slurry supply holes, and polishing the wafers by friction between the wafers and the polishing pads arranged thereon and therebelow; and comparing the B / A value with a global backside ideal plane range (GBIR), wherein "A" is a cross-sectional area of ​​the lower plate, "B" is a sum of cross-sectional areas of wafer accommodating holes formed at the carriers, and "GBIR" represents a height difference between a highest portion and a lowest portion of a surface of each wafer.

[0023] Carriers each formed with a wafer receiving hole and a lower plate configured to support a corresponding one of the carriers may be prepared, and the lower plate together with the corresponding carriers respectively satisfy different B / A values ​​of 25%, 31%, 33% and 35%. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings, which are included here to provide a further understanding of the present disclosure and are incorporated in and constitute a part of this application, illustrate (one or more) embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure. In the drawings: Figure 1 is a side view of a wafer double-side polishing apparatus according to an embodiment of the present invention; Figure 2 is with Figure 1 The corresponding stereogram; Figure 3 and Figure 4 is a diagram showing the carrier and wafer in Figure 1 A plan view of an embodiment of the placement of the lower plate; Figure 5 A method of evaluating a wafer double-side polishing apparatus according to an embodiment of the present invention is shown; and Figure 6 It shows the flatness of a wafer having a diameter of 300 mm when the ratio of the sum of the cross-sectional areas of the wafer receiving holes in the horizontal direction to the cross-sectional area of ​​the lower plate is changed. DETAILED DESCRIPTION

[0025] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings for better understanding.

[0026] However, it is obvious that the embodiments can be modified in various ways, and the aspects of the embodiments should not be interpreted as being limited to the following description. Therefore, the embodiments are provided to ensure that ordinary technicians in the field can better understand the embodiments.

[0027] In addition, it will be understood that relational terms such as "first", "second", "upper / above", and "lower / below", etc. may be interpreted as merely distinguishing one element from another, without necessarily requiring or involving a specific physical or logical relationship or order between the elements.

[0028] A wafer double-sided polishing device according to the present disclosure is intended to provide a wafer with high flatness by performing a double-sided polishing process by adjusting the ratio between the horizontal cross-section of the wafer accommodating hole and the cross-section of the lower plate, thereby adjusting the ratio between the slurry supply area and the entire area of ​​the wafer (the area where the slurry supply is blocked).

[0029] Figure 1 is a side view of a wafer double-side polishing apparatus according to an embodiment of the present invention. Figure 2 is with Figure 1 The corresponding stereogram.

[0030] Reference Figure 1 and Figure 2 The wafer double-side polishing apparatus 1000 includes a lower plate 100 and an upper plate 200, which are arranged to face each other. Polishing pads 120 and 220 may be arranged at an upper portion of the lower plate 100 and at a lower portion of the upper plate 200, respectively.

[0031] A first gear 400 , which is a sun gear, may be provided in a central region of the upper surface of the lower plate 100 , and a second gear 500 , which is an internal gear, may be provided in a peripheral region of the upper surface of the lower plate 100 .

[0032] A plurality of carriers 300 having the same shape are disposed between the polishing pads 120 and 220. The carriers 300 may be engaged between the first gear 400 and the second gear 500.

[0033] A plurality of slurry supply holes 210 may be provided at the upper plate 200. At least one wafer receiving hole, preferably a plurality of wafer receiving holes may be arranged at each carrier 300.

[0034] The paste supplied through the paste supply hole 210 of the upper plate 200 may be a liquid in which fine particles are suspended. For example, the particles may include silicon dioxide particles, and the size of the silicon dioxide particles may be between 40 and 100 nanometers. Here, when the particles are assumed to have a circular shape, the above size refers to the diameter, and when the particles are assumed to have a hexahedral shape, the above size refers to the length of each side.

[0035] In addition, the overall pH of the slurry may be 11 or greater, so that the slurry may exhibit alkaline characteristics. The concentration of the particles in the slurry may be 1% to 1.5%.

[0036] In the wafer double-side polishing apparatus according to the present disclosure, the sum of the cross-sectional areas of the wafer receiving holes in the horizontal direction may be 32% to 34% of the cross-sectional area of ​​the lower plate. Figure 1 A plan view of an embodiment of the arrangement of the lower plate Figure 3 and Figure 4 It can be seen that when the cross-sectional area of ​​the lower plate is A and the sum of the cross-sectional areas of the wafer accommodating holes formed at multiple carriers to accommodate wafers is B, the ratio of B to A can be 0.32 to 0.34 (B / A=0.32-0.34).

[0037] Figure 2 Each carrier 300 included in the wafer double-side polishing apparatus 1000 shown includes a wafer receiving hole and five paste holes having different sizes. Figure 3 and Figure 4 In the illustrated embodiment, a plurality of wafer receiving holes are provided at each of the plurality of carriers. Figure 3 In the embodiment of the present invention, five carriers are arranged on the lower plate, and three wafer receiving holes are provided at each carrier. Figure 4 In the embodiment of the present invention, four carriers are arranged on the lower plate, and four wafer receiving holes are provided at each carrier.

[0038] Even when the number of carriers provided on the lower plate and the number of wafer receiving holes formed at each carrier are different, the sum of the cross-sectional areas of the wafer receiving holes in the horizontal direction can be fixed to 32% to 34% of the cross-sectional area of ​​the lower plate.

[0039] Figure 5 A method for evaluating a wafer double-side polishing apparatus according to an embodiment of the present invention is shown. This method is a method for evaluating a wafer double-side polishing apparatus according to the above-mentioned embodiment.

[0040] In the wafer double-side polishing equipment evaluation method according to this embodiment, the Figure 1 and Figure 2 The wafer double-side polishing equipment is shown.

[0041] First, a wafer double-side polishing apparatus is prepared. Specifically, an upper plate and a lower plate facing each other, polishing pads arranged at a lower portion of the upper plate and at an upper portion of the lower plate, respectively, a first gear arranged in a central region of an upper surface of the lower plate, a second gear arranged in a peripheral region of an upper surface of the lower plate, and a carrier arranged between the polishing pads and engaged with the first gear and the second gear are prepared (S110).

[0042] In this case, a plurality of carriers may be provided, and the plurality of carriers may have the same shape.

[0043] In addition, each carrier may include at least one wafer receiving hole configured to receive a wafer therein. In addition, a plurality of slurry supply holes extending in a vertical direction may be provided at the upper plate.

[0044] In this case, a plurality of the above-mentioned wafer double-side polishing apparatuses may be provided, so that a plurality of wafer double-side polishing apparatuses respectively having different B / A values ​​may be prepared.

[0045] Subsequently, the wafer is double-sided polished using the above-mentioned wafer double-sided polishing apparatus (S120). Specifically, the wafers respectively accommodated in the wafer insertion holes of the carrier are polished by friction between the wafer and the polishing pads arranged above and below it. In this case, according to the action of supplying slurry through the slurry supply hole, the relative surface of each wafer can be chemically and mechanically polished. That is, irregularities, bends, or the like formed at a portion of the wafer surface after a thin film deposition process or an etching process can be removed by mechanical friction between the wafer surface and the polishing pad, and the slurry supplied during the mechanical friction can chemically polish the wafer surface.

[0046] For the polishing pad, a product with a hardness of 83 to 93 Rockwell C scale (HRC) can be used. In addition, the polishing pad can have a compression degree of 0.7% to 3.1%. That is, when it is assumed that each polishing pad has a thickness of 100 before the pressurization of the upper plate and the lower plate, the polishing pad can be compressed to a thickness of 96.9 to 99.3 after pressurization. In this case, the upper plate and the lower plate can be compressed at 100 to 160 g / cm 2 The force of pressure.

[0047] After that, each B / A value is compared with the global backside ideal plane range (GBIR) (S130).

[0048] Here, "A" is the cross-sectional area of ​​the lower plate, and "B" is the sum of the cross-sectional areas of the wafer receiving holes formed at the plurality of carriers. In addition, "GBIR" is an index representing the flatness of the wafer after double-side polishing, and specifically, it represents the height difference between the highest part and the lowest part of the surface (upper surface or lower surface) of the wafer.

[0049] Figure 6 The flatness of a wafer with a diameter of 300 mm, i.e., the comparison result of the B / A value and the global backside ideal plane range (GBIR) in step S130 is shown when the ratio of the sum of the cross-sectional areas of the wafer receiving holes in the horizontal direction to the cross-sectional area of ​​the lower plate is changed.

[0050] Figure 6 The global backside ideal plane range (GBIR) and the thickness profile of the wafer are shown when the ratio of the sum of the cross-sectional areas B of the wafer receiving holes in the horizontal direction to the cross-sectional area A of the lower plate is changed to 25%, 31%, 33% and 35%, respectively.

[0051] When the B / A value changes to 25%, 31%, 33%, and 35%, the GBIR can change to 182 nm, 110 nm, 78 nm, and 89 nm, respectively.

[0052] In addition, if Figure 6 As shown, when the B / A value is 25% and 31%, the thickness profile of the wafer can be convex upward, and when the B / A value is 35%, the thickness profile of the wafer can be concave downward, and when the B / A value is 33%, the thickness profile of the wafer can be close to a flat shape. Therefore, when the B / A value is 33%, the flatness of the wafer can be enhanced without changing the polishing time or the slurry supply amount.

[0053] Therefore, in the wafer double-sided polishing equipment evaluation method according to the present disclosure, it can be evaluated that when the B / A value is 32%-34%, a wafer processed to have a flat surface can be obtained (S140), and the double-sided polishing equipment associated with such a wafer can be determined as the best example.

[0054] That is, the slurry may flow downward from the slurry supply hole of the upper plate in an area other than the wafer receiving hole in which the wafer is arranged. That is, the slurry performing the above-mentioned chemical polishing action may flow downward from the surface of the wafer to be polished to the space behind the wafer. In this case, the ratio of the space to which the slurry behind the wafer flows downward to the cross-sectional area A of the lower plate may be expressed as (100-B) / A. Therefore, when (100-B) / A is small, that is, when the ratio of B / A is large, the supply of the slurry may be blocked by the surface of the wafer, thereby possibly reducing. In this case, the wafer may be polished in the absence of the slurry, so that its central portion may be over-polished. In the opposite case, the slurry may be over-supplied, so that the central portion of the wafer may not be fully polished.

[0055] That is, when the B / A value is 25%, the wafer, especially the central portion of the wafer, may not be sufficiently polished, such as Figure 6 Although not shown, when the B / A value is greater than 41%, the supply of the slurry may be reduced, so that the wafer, especially the central portion of the wafer, may be over-polished.

[0056] When the B / A value is 32% to 34%, the number of carriers in the wafer double-side polishing apparatus and the number of wafer receiving holes in each carrier can be changed, such as Figure 3 and Figure 4 As shown, without changing the dimensions of the upper and lower plates.

[0057] It is obvious from the above description that in the wafer double-sided polishing equipment and the evaluation method thereof according to the present disclosure, the flatness of the wafer undergoing double-sided polishing can be improved without changing the polishing time or the slurry supply by setting the ratio of the sum of the cross-sectional areas B of the wafer accommodating holes in the horizontal direction to the cross-sectional area A of the lower plate to 32% to 34%.

[0058] Although described above mainly in conjunction with embodiments, these embodiments are merely exemplary and not limiting of the present disclosure. It will be appreciated by those skilled in the art that the various modifications and applications shown in the foregoing description are possible without changing the basic features of the embodiments. Therefore, the above embodiments should be understood in all respects as exemplary rather than restrictive. In addition, the scope of the present disclosure should also be interpreted by the appended claims rather than the above detailed description. All modifications or changes derived from equivalent concepts intended to be included within the scope of the present disclosure should also be interpreted as falling within the scope of the present disclosure.

Claims

1. A wafer double-side polishing device, comprising: an upper plate and a lower plate facing each other; polishing pads disposed at a lower portion of the upper plate and at an upper portion of the lower plate, respectively; a first gear and a second gear, the first gear being arranged in a central area of ​​an upper surface of the lower plate, and the second gear being arranged in a peripheral area of ​​the upper surface of the lower plate; as well as a carrier, the carrier being arranged between the polishing pads and being engaged between the first gear and the second gear, The upper plate includes a plurality of paste supply holes extending in the vertical direction. Each of the carriers comprises at least one wafer receiving hole, and The sum of the cross-sectional areas of the wafer receiving holes of the carrier is 32% to 34% of the cross-sectional area of ​​the lower plate.

2. The wafer double-side polishing device according to claim 1, characterized in that: The carriers have the same shape, and the at least one wafer receiving hole of each carrier includes three wafer receiving holes; and The carrier includes five carriers engaged between the first gear and the second gear.

3. The wafer double-side polishing device according to claim 1, characterized in that: The carriers have the same shape, and the at least one wafer receiving hole of each carrier includes four wafer receiving holes; and The carrier includes four carriers engaged between the first gear and the second gear.

4. The wafer double-side polishing device according to claim 1, characterized in that: The slurry supplied to the slurry supply hole includes silicon dioxide particles having a size of 40 to 100 nanometers.

5. The wafer double-side polishing device according to claim 4, characterized in that: The pH of the slurry is 11 or greater.

6. The wafer double-side polishing device according to claim 4, characterized in that: The particle concentration of the slurry is 1% to 1.5%.

7. The wafer double-side polishing device according to claim 4, characterized in that: Each of the polishing pads has a hardness of 83 to 93 HRC.

8. The wafer double-side polishing device according to claim 4, characterized in that: Each of the polishing pads has a compression degree of 0.7% to 3.1%.

9. The wafer double-side polishing device according to any one of claims 1 to 3, characterized in that: The wafers are respectively accommodated in the wafer accommodation holes of the carrier, and the lower plate and the upper plate are 100 to 160 g / cm 2 The force is used to apply pressure.

10. A method for evaluating a wafer double-side polishing device, comprising: preparing a wafer double-side polishing apparatus, the wafer double-side polishing apparatus comprising an upper plate and a lower plate facing each other, polishing pads arranged at a lower portion of the upper plate and at an upper portion of the lower plate, respectively, a first gear arranged in a central area of ​​an upper surface of the lower plate, a second gear arranged in a peripheral area of ​​the upper surface of the lower plate, and a carrier arranged between the polishing pads while being engaged between the first gear and the second gear, the upper plate comprising a plurality of slurry supply holes extending in a vertical direction, each of the carriers comprising at least one wafer receiving hole; Respectively accommodating wafers in the wafer accommodating holes of the carrier, supplying slurry through the slurry supply holes, and polishing the wafers by friction between the wafers and polishing pads arranged above and below the wafers; Compare the B / A value with the global back ideal plane range GBIR, Wherein, "A" is the cross-sectional area of ​​the lower plate, "B" is the sum of the cross-sectional areas of the wafer receiving holes formed at the carrier, and "GBIR" represents the height difference between the highest part and the lowest part of the surface of each wafer.

11. The wafer double-side polishing equipment evaluation method according to claim 10, characterized in that: Carriers each formed with a wafer receiving hole and a lower plate configured to support a corresponding one of the carriers are prepared, and the lower plate together with the corresponding carriers respectively satisfies different B / A values ​​of 25%, 31%, 33% and 35%.

12. The wafer double-side polishing equipment evaluation method according to claim 10, characterized in that: preparing carriers having the same shape, each of the carriers having three wafer receiving holes; and The carrier includes five carriers engaged between the first gear and the second gear.

13. The wafer double-side polishing equipment evaluation method according to claim 10, characterized in that: preparing carriers having the same shape, each of the carriers having four wafer receiving holes; and The carrier includes four carriers engaged between the first gear and the second gear.

14. The wafer double-side polishing equipment evaluation method according to claim 10, characterized in that: During polishing, the lower plate and the upper plate are polished at 100 to 160 g / cm 2 The force is used to apply pressure.

15. The wafer double-side polishing equipment evaluation method according to claim 10, characterized in that: The slurry supplied to the slurry supply hole includes silicon dioxide particles having a size of 40 to 100 nanometers, a pH of the slurry is 11 or more, and a particle concentration of the slurry is 1% to 1.5%.

16. The wafer double-side polishing equipment evaluation method according to claim 10, characterized in that: Polishing pads each having a hardness of 83 to 93 HRC and a compression degree of 0.7% to 3.1% were prepared.

Images