TW202122210A - Wafer single side polishing method, wafer manufacturing method and wafer single side polishing device - Google Patents

Abstract

To provide a wafer single side polishing method, a wafer manufacturing method and a wafer single side polishing device, capable of reducing the circumferential flatness unevenness amount of a wafer outer periphery section. A wafer single side polishing method, characterized by including a polishing step of performing polishing on a surface to be polished of a wafer by rotating a polishing head and a surface plate while pressing the wafer held by the polishing head to a polishing pad fixed to the surface of the surface plate, wherein the wafer is polished at a rotation rate above 25 degrees/minute and below 60 degrees/minute.

Description

Single-side polishing method of wafer, manufacturing method of wafer, and single-side polishing device of wafer

The present invention relates to a single-side polishing method of a wafer, a manufacturing method of a wafer, and a single-side polishing device of a wafer.

In the manufacture of wafers, various steps are carried out, one of which is the polishing step of the wafer. In the wafer polishing step, depending on the purpose, both sides of the wafer are polished, or only one side of the wafer is polished.

In single-sided polishing of wafers, high flatness of the wafer surface is required. For example, Patent Document 1 discloses a polishing pad having excellent flatness on the surface of an object to be polished and a method of manufacturing the same.

In addition, Patent Document 2 discloses a wafer polishing method that effectively prevents the outer periphery of the wafer from sagging, and a polishing pad for wafer polishing suitable for use in the polishing method of the wafer. [Advanced Technical Literature] [Patent Literature]

[Patent Document 1] International Publication No. 2015/178289 [Patent Document 2] Patent Publication No. 2003-142437

[The problem to be solved by the invention]

In recent years, from the viewpoint of the miniaturization of components and the expansion of the device formation area of the wafer, high flatness is also required near the outermost periphery of the wafer. Not only the flatness and the amount of surface displacement near the outermost periphery of the wafer, but also the outer periphery The direction also requires flattening. However, in the polishing pad described in Patent Document 1, a multi-layered polishing pad is used to reduce minute defects. As a flatness index, only changes in ESFQR are measured, and unevenness in the circumferential direction of the wafer is not noticed. In addition, in the polishing pad described in Patent Document 2, it is necessary to improve the sagging of the outer periphery of the wafer based on the relationship between the surface roughness of the polishing pad and the compressibility, but the unevenness in the circumferential direction of the wafer is not noticed.

In addition, "ESFQR (Edge Site flatness Front reference least sQuares Range)" in this specification means the difference between the maximum value and the minimum value of ESFQR specified by SEMIM67. Specifically, for the measurement of ESFQR, a flatness measuring device (manufactured by KLA-Tencor: Wafer sight 2) was used. ESFQR is an index indicating the flatness of the part on the outer periphery (edge) of the wafer. ESFQR means that the outer periphery of the divided wafer is divided into many (for example, 72) fan-shaped regions (parts). The inner plane of the part using the least square method to calculate the data in the part is used as the reference. According to the displacement amount of the inner plane of this part, each part There is 1 data in. In addition, "ESFQR Range" in this specification is the difference between the maximum and minimum ESFQR calculated for each part of the fan shape, and represents the amount of unevenness in the circumferential direction of the wafer. The ESFQR Range site in this specification, for example, on a wafer with a diameter of 300mm, the area 2mm (millimeters) from the outermost circumference in the diameter direction is the exclusion area, and the outer reference end of the inner circumference is toward the center side in the radial direction. The extended sector has 72 roughly rectangular divisions surrounded by two straight lines of 300 mm in length and a circular arc corresponding to 5 degrees (±2.5 degrees) in the peripheral direction of the wafer. Therefore, the ESFQR Range is a value calculated from the maximum value and the minimum value among these 72 ESFQR values.

An object of the present invention is to provide a single-side polishing method for a wafer, a method for manufacturing a wafer, and a single-side polishing apparatus for a wafer that can reduce the unevenness in the circumferential flatness of the outer periphery of the wafer.

The inventors of the present invention have intensively studied a polishing method that can reduce the unevenness in the circumferential flatness of the wafer outer periphery. As a result, by increasing the wafer rotation rate held by the chuck, they have found that the circumference of the wafer outer periphery can be reduced. The amount of unevenness in direction flatness. It is considered that the cause is uneven surface pressure transferred to the back surface of the wafer due to unevenness of the chuck of the polishing apparatus and the like.

According to the results of the inventors’ research on creating various polishing pads with different characteristics, the factors to improve the wafer rotation rate include (1) the compression rate of the polishing pad, (2) the contact angle of the polishing pad to pure water, and (3) The composition of the polishing pad, (4) the gap between the outer periphery of the wafer and the inner periphery of the retainer, (5) the number of rotations of the polishing head and the table during polishing, and (6) the polishing pressure. By managing these elements, the rotation rate of the wafer can be managed, and the unevenness of the flatness can be reduced. In addition, the factors that increase the wafer rotation rate may be applied alone, or they may be applied in plural. In other words, it is not necessary for all the elements to satisfy these ranges at the same time as the ranges required for each element to increase the wafer rotation rate, as long as the ranges are satisfied at least individually.

Based on FIGS. 4 to 8, the relationship between the factors that improve the wafer rotation rate discussed by the inventors and the wafer rotation rate will be briefly described. These Figures 4 to 8 are used to create various polishing pads with different characteristics, based on the acquired data. Figure 4 shows the relationship between wafer rotation rate (degrees/min) and ESFQR Range (nm). According to Figure 4, it is clear that the larger the rotation rate, the smaller the ESFQR Range (nm) (improvement). Therefore, it is possible to achieve the objective of the present invention to reduce the unevenness of the circumferential flat portion of the outer peripheral portion of the wafer by taking a countermeasure against the increase in the rotation rate of the wafer.

Figure 5 is a graph showing the relationship between the compression rate (Nap compression rate) (%) of the nap layer of the polishing pad and the wafer rotation rate (a.u.). According to Figure 5, it is understood that the greater the Nap compression rate (%), the greater the wafer rotation rate (a.u.). Therefore, by increasing the Nap compression rate (%) to a certain extent, the wafer rotation rate (a.u.) becomes larger, and the unevenness of the circumferential flat portion of the outer periphery of the wafer can be reduced. Here, as a specific unit of the wafer rotation rate (a.u.) in FIG. 5 to FIG. 8 described later, for example, (degree/min).

FIG. 6 is a diagram showing the relationship between the contact angle (degrees) of the pure water on the surface of the polishing pad (wafer polishing surface) and the wafer rotation rate (a.u.). According to Figure 6, it is understood that the greater the contact angle (degree) of the polishing pad's wafer polishing surface to pure water, the greater the wafer rotation rate (a.u.). Therefore, by increasing the contact angle (degrees) of the wafer polishing surface of the polishing pad to pure water to a certain extent, the wafer rotation rate (au) increases, and the unevenness of the peripheral flat portion of the wafer outer periphery can be reduced. .

Figure 7 shows the relationship between the inner diameter of the retainer ring (mm) and the wafer rotation rate (a.u.). The diameter of the wafer used in Figure 7 is 300mm. According to Figure 7, it is understood that the larger the inner diameter of the retainer, the larger the wafer rotation rate (a.u.). Therefore, by increasing the inner diameter (mm) of the retainer ring to some extent, the wafer rotation rate (a.u.) increases, and the unevenness of the circumferential flat portion of the outer periphery of the wafer can be reduced. The so-called retainer inner diameter (mm) is large, because the gap with the outer periphery of the wafer becomes larger, and the wafer rotation rate (a.u.) becomes larger.

FIG. 8 is a graph showing the relationship between polishing pressure (g/cm ² ) and wafer rotation rate (au) during wafer polishing. According to Fig. 8, it is understood that although the relationship is not linear, the ^{greater the polishing pressure (g/cm 2} ), the greater the wafer rotation rate (au). Therefore, by increasing the polishing pressure (g/cm ² ) to a certain extent, the wafer rotation rate (au) becomes larger, and the unevenness in the circumferential flat portion of the outer periphery of the wafer can be reduced. [Means to solve the problem]

The polishing method of the present invention is a single-sided polishing method for wafers, characterized in that it includes a polishing step, pressing the wafer held by the polishing head to a polishing pad fixed on the surface of the platform, and rotating the polishing head and the platform to perform the polishing on the crystal The round surface to be polished is polished. In the polishing step, the rotation rate of the wafer is 25 degrees/min or more and 60 degrees/min or less, and the wafer is polished.

According to this invention, it is possible to reduce the unevenness in the circumferential flat portion of the outer peripheral portion of the wafer.

In the single-sided polishing method of the wafer, it is preferable to use a polishing pad having a raised layer with a compression ratio of 58.5% or more and 70% or less as the polishing pad.

In the single-sided polishing method of the wafer, as the polishing pad, the contact angle of the pure water on the surface of the wafer to be polished is preferably 58 degrees or more and 70 degrees after the pure water is dropped for 1800 seconds. pad.

In the single-sided polishing method of the wafer described above, it is preferable to use a polishing pad that does not use a single raised layer of a non-woven fabric as the polishing pad.

In the single-sided polishing method of the wafer, the inner diameter of the retainer of the wafer is maintained, and the ratio of the inner diameter of the retainer to the diameter of the wafer is preferably the following formula Retainer inner diameter/wafer diameter=1.0015 or more and 1.0067 or less Represents the guard ring.

In the single-sided polishing method of the wafer, the number of rotations of the table during polishing is preferably set at 15 rpm or more and 80 rpm or less.

In the single-sided polishing method of the wafer, the polishing pressure is preferably set to 100 g/cm ² or more and 300 g/cm ² or less.

In the single-sided polishing method of the wafer, the relationship between the polishing conditions and the rotation rate of the wafer is determined in advance, and it is preferable to determine the polishing conditions based on the relationship.

In the single-sided polishing method of the wafer, the polishing conditions are preferably any of the compressibility of the polishing pad, the contact angle, the ratio of the inner diameter of the guard ring to the diameter of the wafer, the number of rotations of the polishing table, and the amount of polishing pressure. Items or combinations thereof.

In addition, the manufacturing method of the present invention is a method of manufacturing a wafer, which is characterized by including a single-sided finishing step for processing at least one side of the wafer. In the single-sided finishing step, the single-sided polishing method of the wafer is used, Polishing is performed on the polished surface of the above-mentioned wafer.

In addition, the polishing device of the present invention is a single-side polishing device for wafers, which is characterized by comprising: a head rotating shaft member provided with a polishing head for holding the wafer; a platform for fixing the polishing pad to the surface; and head driving means, Driving the head rotating shaft member; a stage driving means to drive the stage; a wafer pressure adjusting means to adjust the pressure of pressing the wafer to the polishing pad; and a polishing condition determination unit to determine polishing conditions; the polishing condition determination unit , Determine the polishing conditions so that the rotation rate of the wafer is 25 degrees/min or more and 60 degrees/min or less. [Effects of the invention]

According to the present invention, there are provided a single-side polishing method for a wafer, a method for manufacturing a wafer, and a single-side polishing apparatus for a wafer that can reduce the unevenness in the circumferential flatness of the outer periphery of the wafer.

Hereinafter, an embodiment of the present invention will be described in detail. [Configuration of Grinding Device] First, referring to the attached drawings, a single-side polishing apparatus 1 according to an embodiment of the present invention will be described. As shown in Figures 1 and 2, the single-sided polishing device 1 includes a plurality of head rotating shaft members 11, polishing heads 12 provided on each head rotating shaft member 11, back pads 13 provided on each polishing head 12, and The retainer 14 of each back pad 13, the platform 15, the polishing pad 16 provided on the platform 15, the head driving means 20 that drives each head rotating shaft member 11, the platform driving means 30, the polishing liquid supply means 40, the adjustment press The wafer pressure adjusting means 50, the polishing control means 60, and the polishing condition determination unit 70 are used to adjust the pressure between the wafer W held by each polishing head 12 and the polishing pad 16.

The head rotation shaft member 11 is constituted by a shaft-shaped member. The head rotating shaft member 11 is rotatable around an axis, and is connected to the rotating shaft of the head driving means 20 provided with a rotating drive source such as a motor to rotate the polishing head 12.

The grinding head 12 is connected to the lower end of the head rotating shaft member 11. The polishing head 12 is composed of a circular thick plate with the center of rotation of the head rotating shaft member 11 as the center. The polishing head 12 uses the surface tension of water or the like to hold the surface (back surface) opposite to the surface (surface) of the wafer W to be polished.

The back pad 13 is a circular plate-shaped body with the same diameter as the polishing head 12 and is arranged under the polishing head 12. The back pad 13 is made of, for example, a porous resin material, and may contain liquid such as water.

The retainer 14 is provided on the outer peripheral portion of the lower surface of the back pad 13 and is formed of a ring-shaped member. The guard ring 14 contacts the outer peripheral end of the wafer W and keeps the wafer W from deviating from the gap between the back pad 13 and the polishing pad 16 described later. When polishing the wafer W, the guard ring 14 may or may not contact the polishing pad 16 during polishing. In the case of contact, the thickness unevenness of the guard ring 14 affects the unevenness of the circumferential flatness of the outer peripheral portion of the wafer W, but according to the method of the present invention, the cost is not increased, and the unevenness in the circumferential direction can be reduced.

The platform 15 is arranged opposite to the plurality of polishing heads 12 to form a circular shape. The platform 15 is supported to rotate freely, and rotates in the same direction as the rotation direction of the polishing head 12 or in the opposite direction. On the platform 15, a polishing pad 16 for polishing the polished surface of the wafer W is stuck.

The polishing pad 16 is composed of a non-woven fabric as a base material and a nap layer laminated on one surface of the non-woven fabric. The polishing of the wafer W is performed by pressing the surface of the wafer W (the surface facing the polishing pad 16) to the nap layer of the polishing pad 16 with a predetermined force. Here, the so-called nap layer refers to a layer having many pores formed by foaming.

The head driving means 20 rotates the head rotating shaft member 11 of the polishing head 12.

The platform driving means 30 is composed of a motor or the like, and is rotatably connected to the platform rotation shaft member 31 under the platform 15.

The polishing liquid supply means 40 is provided above the platform 15 and is configured to supply a slurry-like polishing liquid to the contact surface of the polishing pad 16 and the wafer W using a nozzle 41.

The wafer pressure adjusting means 50 adopts a fixed pressure method to adjust the pressure of the wafer W against the polishing pad 16. In the fixed pressure method, the entire polishing head 12 is pressed by cylindrical pressure, and the polishing head 12 is pressed to the upper surface of the wafer W via the back pad 13, and the polished surface of the wafer W is pressed to the polishing pad 16 on the platform 15.

The polishing control means 60 controls at least one of the head driving means 20, the stage driving means 30, the polishing liquid supply means 40, and the wafer pressure adjusting means 50 based on the predetermined polishing conditions determined by the polishing condition determination unit 70 to control one side Operation of the polishing device 1.

The polishing condition determination unit 70 memorizes the relationship between the polishing condition and the wafer rotation rate determined in advance, and determines the polishing condition based on the memory relationship. At that time, the polishing conditions may be determined automatically using a computer or the like.

[Grinding method] Next, an example of a single-side polishing method for a wafer using the single-side polishing device 1 will be described. The polishing condition determination unit 70 of the single-side polishing apparatus 1 obtains and memorizes the relationship between the polishing condition and the wafer rotation rate before the polishing of the wafer W. When the single-sided polishing apparatus 1 sets a command to start polishing the wafer W, the polishing condition determination unit 70 determines the polishing conditions based on the relationship between the memorized polishing conditions and the wafer rotation rate. Then, under the determined polishing conditions, the polishing control means 60 controls the head driving means 20, the stage driving means 30, the polishing liquid supply means 40, and the wafer pressure adjusting means 50 to perform the polishing step of the wafer W. Specifically, first, a polishing pad 16 suitable for the determined polishing conditions is selected, and the platform 15 is arranged. Next, on the polishing pad 16 of the stage 15, a predetermined amount of polishing liquid is supplied by the polishing liquid supply means 40. Then, the polishing head 12 holding the wafer W is driven by the head driving means 20 to descend while rotating, and the wafer W is brought into contact with the polishing pad 16 of the table 15 rotated by the driving of the table driving means 30. After that, the wafer pressure adjusting means 50 adjusts the pressure for pressing the wafer W to the polishing pad 16 to perform a polishing step of polishing the polished surface of the wafer W.

In this embodiment, in the polishing step, the rotation rate of the wafer W is controlled to be 25 degrees/min or more and 60 degrees/min, and the polished surface of the wafer W is polished. By controlling the rotation rate of the wafer W to be 25 degrees/min or more, the unevenness in the circumferential flatness of the outer periphery of the wafer can be reduced. In addition, by setting the rotation rate of the wafer W to 60 degrees/min or less, it is possible to prevent the wafer W from scratching and wafer jumping out. On the other hand, when the rotation rate of the wafer W exceeds 60 degrees/min, the back pad may become unable to hold the wafer. The rotation rate of the wafer W is more preferably 25 degrees/min or more and 40 degrees/min or less, and more preferably 26 degrees/min or more and 30 degrees/min or less. In addition, regarding the rotation rate of the wafer W, within the range of 25 degrees/min or more and 60 degrees/min or less, it is preferable that the closer to the range of 26 degrees/min or more and 30 degrees/min or less, the more the effects of the present invention can be exerted. . Therefore, any numerical value in the range of 25 degrees/min or more and 60 degrees/min or less can exhibit its corresponding effect even if the range is divided.

The rotation rate of the wafer W can be confirmed when the polishing conditions are selected. Alternatively, the rotation rate may be obtained by simulation. In addition, it is also possible to observe the grooves of the wafer W before and after polishing, or to directly observe the rotation rate of the wafer during actual polishing by using a sensor or other real-time detection. When observing the position of the groove to obtain the rotation rate of the wafer W, specifically, observing the position of the groove of the wafer W before and after polishing, and calculating the rotation per minute by dividing the angle of the groove position movement by the polishing time (minutes) Rate (degrees/min).

In this embodiment, it is better to control the ESFQR Range to 6.5 nm or less by controlling the rotation rate.

In this embodiment, for example, as the polishing pad 16, by using a polishing pad having a fluffing layer with a compression rate of 58.5% or more, the rotation rate of the wafer W in the polishing step can be controlled to be 25 degrees/min or more. The compression rate of the raised layer can be measured by the following method using a shopper-type thickness measuring device, for example. (1) Press a predetermined initial load for a certain period of time, and measure its thickness (t ₀ ). (2) Load the predetermined additional load on it, and measure the thickness (t ₁ ) after a certain period of time. (3) Calculate the compression ratio by the following formula. Compression rate (%)={(t ₀ －t ₁ )/ t ₀ }×100 Because the abrasion of the raised layer is very small, it can be dealt with. The compression rate of the raised layer is ideally below 70%. The compression rate of the raised layer is more preferably 58.5% or more and 63% or less. In addition, with regard to the compression ratio of the raised layer, in the range of 58.5% to 70%, and more preferably, the closer to the range of 58.5% to 63%, the more the effect of the present invention can be exhibited. Therefore, any value within the range of 58.5% to 70% can exhibit its corresponding effect even if the range is divided.

Also, for example, in the present embodiment, as the polishing pad 16, by using a polishing pad with a contact angle of 58 degrees or more and 70 degrees or less to pure water on the surface of the polishing wafer W, it is possible to control the crystal in the polishing step. The rotation rate of circle W is above 25 degrees/min and below 60 degrees/min. The polishing pad 16 is a polishing pad that has a contact angle of more than 70 degrees to pure water on the surface of the polished wafer W, and it is difficult to manufacture it in production. In addition, the contact angle in this specification refers to the contact angle between the water droplet and the polishing pad surface measured by analyzing the image of the side surface after 1 μm of pure water is dropped on the surface of the polishing pad 16, and after 1800 seconds from the pure water droplet.

The compressibility of the raised layer and the contact angle of the polishing pad can be adjusted to desired values, for example, according to the selection of the resin and additives constituting the polishing pad 16, the film formation process conditions and the buffing allowance control. For example, the compression rate is adjusted according to the type of resin, the contact angle is adjusted according to the type of additive, etc., and the compression rate and the contact angle can be individually adjusted. Examples of the resin constituting the polishing pad include polyurethane resin and polyimide resin. Examples of additives include pigments, film-forming stabilizers, and foam-forming agents. Moreover, as a pigment, carbon black etc. are mentioned, for example. Examples of the film-forming stabilizer include nonionic surfactants and the like. Examples of foaming agents include anionic surfactants and the like.

In this embodiment, from the viewpoint of further increasing the rotation rate, it is preferable to adopt a retainer whose inner diameter to the diameter of the wafer W (the inner diameter of the retainer 14/the diameter of the wafer W) is 1.0015 or more and 1.0067 or less. For example, when the diameter of the wafer W is 300 mm, the inner diameter of the guard ring 14 is preferably 300.5 mm or more and 302 mm or less.

In this embodiment, from the viewpoint of further increasing the rotation rate, it is preferable to use the number of rotations of the table 15 during polishing, and it is more preferable to be 15 rpm or more. On the other hand, from the viewpoint of preventing the outer circumference from sagging, the number of rotations of the table 15 during polishing is preferably 80 rpm or less. The number of rotations of the table 15 during polishing is more preferably 20 rpm or more and 40 rpm or less. If the above-mentioned number of rotations is less than 40 rpm, there is no danger that the absolute value of the flatness will deteriorate. In addition, the number of rotations described above is within the range of 15 rpm or more and 80 rpm or less, and it is more desirable that the closer to the range of 20 rpm or more and 40 rpm or less, the more the effects of the present invention can be exerted. Therefore, any numerical value in the range of 15 rpm or more and 80 rpm can exhibit the corresponding effect even if the range is divided.

In this embodiment, from the viewpoint of further increasing the rotation rate of the wafer W, the polishing pressure (pressure for pressing the wafer W to the polishing pad 16 during polishing) is preferably set to 100 g/cm ² or more. On the other hand, from the viewpoint of preventing wafer cracking, the polishing pressure is preferably 300 g/cm ² or less. The grinding pressure is more preferably 125 g/cm ² or more and 200 g/cm ² or less. If the polishing pressure is 200 g/cm ² or less, the flow of polishing agent between the polishing pad 16 and the wafer W is not hindered, and there is no risk of causing defects in the wafer W. In addition, the polishing pressure ^{is within the range of 100 g/cm 2} or more and 300 g/cm ² or less, and more preferably, the closer to the range of 125 g/cm ² or more and 200 g/cm ² or less, the more the effect of the present invention can be exerted. Therefore, any numerical value within the range of 100 g/cm ² or more and 300 g/cm ² or less can exhibit the corresponding effect even if the range is divided.

In this embodiment, the wafer W to be polished is not particularly limited. As the wafer W, for example, a silicon wafer, a SiC wafer, and the like are mentioned. In this embodiment, the diameter of the wafer W to be polished is not particularly limited. For example, a wafer with a diameter of 150 mm, a wafer with a diameter of 200 mm, and a wafer with a diameter of 300 mm are mentioned. When polishing these wafers of different diameters, the same is true as described above. To maintain the ratio of the inner diameter of the wafer retainer to the wafer diameter, it is best to use the retainer represented by the formula. Retainer inner diameter/wafer diameter=1.0015 or more and 1.0067 or less

The polishing liquid used in the polishing method of this embodiment is not particularly limited. The general polishing liquid used for polishing wafers can also be used in this embodiment.

[Wafer manufacturing method] Next, a description will be given of a method of manufacturing a silicon wafer including the single-side polishing method of this embodiment. The outline of the manufacturing method of the silicon wafer is a method in which the silicon wafer is manufactured by the Czochralski method (single crystal growth method), and the wafer W is polished by the above-mentioned single-sided polishing method.

As shown in Figure 3, the manufacturing method of a silicon wafer has a pulling step S1, a block processing step S2, a cutting step S3, a pre-processing step S4, a two-side simultaneous polishing step S5, a single-side polishing device setting step S6, and polishing conditions The decision step S7, the polishing step S8, and the wafer take-out step S9 are determined.

Here, the single-side polishing device setting step S6, the polishing condition determination step S7, the polishing step S8, and the wafer take-out step S9 constitute a single-side finishing step S20.

The pulling step S1 is a step of pulling a single crystal from the silicon melt by the Czochralski method (single crystal growth method). In this way, a columnar single crystal ingot is obtained. The block processing step S2 is a step of processing a single crystal ingot into a block. In the block processing step S2, the outer periphery of the single crystal ingot is ground, and after the groove processing is performed according to the crystal orientation, the single crystal ingot is cut into plural blocks using, for example, a band saw.

In the dicing step S3, using an inner peripheral knife cutter or a steel wire saw, the dicing block is, for example, a plurality of silicon wafers with a thickness of about 1 mm. In the pre-processing step S4, in order to make the two sides of the wafer parallel, rough lapping is carried out with an alumina abrasive, etc., and etching is carried out as necessary, and then the unevenness of the wafer surface is flattened. Processing.

In the simultaneous double-sided polishing step S5, a highly flat mirror finish is performed on the wafer subjected to the pre-processing. For example, the use of colloidal silica (colloidal silica) liquid etc. to carry out double-sided polishing (polishing), and more efforts to flatness, to form a predetermined flatness of the wafer.

The wafer with a predetermined flatness is set by the single-side polishing device in the single-side polishing device setting step S6. In the polishing condition determination step S7, the polishing condition of the polishing condition determining part of the polishing control means is determined, the polishing pad suitable for the determined polishing condition is arranged in the platform, and each part of the single-side polishing device, specifically, instructs the head driving means, The polishing conditions are determined by the platform driving means, the polishing liquid supply means, and the wafer pressure adjustment means. In the polishing step S8, polishing is performed according to the determined polishing conditions, and the wafer is taken out in the wafer taking-out step S9. According to the single-sided polishing device setting step S6, the polishing condition determination step S7, the polishing step S8, and the wafer take-out step S9 in the single-sided finishing step S20, the silicon wafer after the flatness processing is removed by performing the polishing process At the same time as surface defects and damages, the surface roughness of silicon wafers can be adjusted.

Each silicon wafer taken out in the wafer take-out step S9 is cleaned, for example, with an alkaline solution in the cleaning step S10.

The wafer final inspection step S11 is a step of inspecting particles or defects on the surface of the silicon wafer using a wafer surface inspection device or the like. After checking the quality of the wafers, the qualified products are packaged and shipped.

[Effects of the implementation form] As mentioned above, according to the findings of the present inventors, because single-sided polishing is a mechanism that clamps the backside of the wafer and polishes the surface side, the uneven shape of the chuck on the holding side, the uneven thickness of the holding material of the backing pad, and the thickness of the guard ring The surface pressure transferred to the back surface of the wafer has unevenness due to the influence of the auxiliary materials, and it is understood that the processing allowance of the outer periphery of the silicon wafer is uneven in the circumferential direction. According to the above-mentioned embodiment, by increasing the rotation rate of the wafer, it is possible to average out the uneven surface pressure caused by the sub-materials transferred to the back surface. Therefore, the unevenness of wafer flatness in the circumferential direction can be reduced.

In the above embodiment, as the factors to increase the wafer rotation rate, focus on the compression ratio of the polishing pad, the contact angle, the ratio of the inner diameter of the guard ring to the diameter of the wafer, the number of rotations of the polishing table, and the amount of polishing pressure, alone or in combination For any of the elements, after obtaining the desired rotation rate of the wafer, the degree of freedom in selecting the polishing conditions is high, and there is an effect that polishing according to the condition of the wafer can be performed.

[Modifications] In addition, the present invention is not limited to the above-mentioned embodiment. Various improvements and design changes can be made without departing from the scope of the present invention.

For example, in the above embodiment, as the back pad 13 and the retainer 14 in the single-sided polishing device 1, an example of a template in which the retainer 14 is provided on the outer periphery of the back pad 13 is used as an integrated template, but the polishing device body has a retainer ring. can.

Also, for example, in the above-mentioned embodiment, as the polishing pad 16 in the single-sided polishing device 1, an example in which a polishing pad having a non-woven fabric and a raised layer as a base material is used is described, but the polishing pad uses a single-sided raised layer that does not use a non-woven fabric. Body polishing pads are also available. The use of a polishing pad that does not use a non-woven raised layer alone is not affected by the thickness fluctuation and density of other base layers such as non-woven fabrics, and the deterioration of the ESFQR Range can be suppressed. Alternatively, a polishing pad using a resin film or the like as a base material may also be used. [Example]

The selection of polyurethane resin, by adjusting CB (carbon black), film forming stabilizer and solvent (DMF) and other additives, film forming process conditions and polishing (buffing) processing allowance, the production compression rate and contact angle are different Of polishing pads (pads A~C). In addition, in the pads A to C, physical properties other than the control compression rate and contact angle did not change. Table 1 shows the physical properties of pads A to C.

[Table 1] Trial pad Physical properties thickness density Nap compression rate Contact angle unit mm g/cm ³ % degree Pad A 0.75 0.53 44.3 38 Pad B 0.76 0.53 58.5 58 Pad C 0.77 0.52 61.6 65

In polishing, the pads A to C described above were used as polishing pads. In addition, as a back pad and a guard ring, a template type in which these are integrated is used. In addition, as the above-mentioned template, a Fujibou-made template (POLYPAS_Template) of 10 μm in the circumferential thickness range (36-point measurement) at the position of the retainer inner diameter of 301 mm and the back pad diameter of 290 mm was used.

The wafers to be polished are single crystal silicon wafers with a diameter of 300mm. The average ESFQD before single-sided polishing (SMP) is 60 wafers each with an average value of 0nm to 5nm. The grinding pressure is 150 g/cm ² , and the rotation number of the grinding pad and the platform is 30 rpm. In the polishing liquid, 0.3wt% of colloidal silica with a particle size of 35nm was used to polish the wafer for 4 minutes so that the machining allowance was above 500nm and below 1000nm.

[Measurement of Rotation Rate] By observing the position of the groove before and after polishing, the rotation rate of the wafer W is measured. The results are shown in Table 2.

[Calculation of ESFQR Range] Regarding the polished wafer, the ESFQR Range is calculated according to the following method, and the amount of unevenness in flatness of the outer periphery in the circumferential direction is evaluated. The results are shown in Table 2. Taking the area 2mm in the diameter direction from the outermost circumference of the wafer as the exclusion area, the fan-shaped length of the outer reference end on the inner side extending toward the center side in the radial direction is 300mm and 2 straight lines equivalent to 5 degrees in the outer circumference of the wafer (±2.5 The 72 roughly rectangular divisions surrounded by the arc of (degrees) are regarded as the ESFQR Range. Then, a flatness measuring device (made by KLA-Tencor: Wafer sight 2) was used to measure ESFQR in these 72 locations. ESFQR Range is calculated based on the difference between the maximum value and the minimum value among the 72 measured ESFQR values.

[Table 2] Rotation rate (degree/min) ESFQR Range(nm) Pad A 6.5 9.98 Pad B 25.0 5.8 Pad C 26.4 5.3

As shown in Table 2, by controlling the rotation rate of the wafer to be 25 degrees/min or more and 60 degrees/min or less to polish the wafer, the unevenness in the circumferential flatness of the outer periphery of the wafer can be reduced.

1: Single-sided grinding device 11: Head rotating shaft component 12: Grinding head 13: back pad 14: Guard ring 15: platform 16: polishing pad 20: Head drive means 30: Platform-driven means 31: Platform rotation axis component 40: Grinding liquid supply means 41: Nozzle 50: Wafer pressure adjustment method 60: Grinding control means 70: Grinding condition determination department W: Wafer S20: Single-sided completion steps

[Fig. 1] is a schematic diagram showing the schematic configuration of a polishing apparatus according to an embodiment of the present invention used in the single-side polishing method of the present invention; [FIG. 2] A block diagram showing the schematic configuration of a polishing apparatus according to an embodiment of the present invention used in the single-side polishing method of the present invention; [FIG. 3] is a flowchart illustrating a method of manufacturing a silicon wafer according to an embodiment of the present invention using a single-side polishing method according to an embodiment of the present invention; [Figure 4] A diagram showing the relationship between wafer rotation rate and ESFQR Range; [Figure 5] A diagram showing the relationship between the compression rate (Nap compression rate) of the fluffing layer of the polishing pad and the wafer rotation rate; [Figure 6] A diagram showing the relationship between the contact angle of the polishing pad's polishing wafer surface to pure water and the wafer rotation rate; [Figure 7] A diagram showing the relationship between the inner diameter of the retainer ring and the wafer rotation rate; and [Fig. 8] A graph showing the relationship between polishing pressure and wafer rotation rate during wafer polishing.

11: Head rotating shaft component

12: Grinding head

13: back pad

14: Guard ring

15: platform

16: polishing pad

20: Head drive means

30: Platform-driven means

31: Platform rotation axis component

40: Grinding liquid supply means

41: Nozzle

50: Wafer pressure adjustment method

60: Grinding control means

70: Grinding condition determination department

W: Wafer

Claims (15)

A single-side polishing method for wafers, characterized in that: include: In the polishing step, pressing the wafer held by the polishing head to a polishing pad fixed on the surface of the platform, and performing polishing processing on the polished surface of the wafer by rotating the polishing head and the platform; In the polishing step, the rotation rate of the wafer is 25 degrees/min or more and 60 degrees/min or less, and the wafer is polished. For example, the single-side polishing method for wafers in claim 1, characterized in that: Among them, as the above-mentioned polishing pad, a polishing pad having a raised layer with a compressibility of 58.5% or more and 70% or less is used. For example, the single-side polishing method for wafers in claim 1, characterized in that: Among them, as the above-mentioned polishing pad, the contact angle of the pure water on the surface of the surface of the polishing wafer with respect to pure water is a polishing pad that is 58 degrees or more and 70 degrees or less after 1800 seconds after the pure water is dropped. For example, the single-side polishing method for wafers in claim 2, which is characterized in that: Among them, as the above-mentioned polishing pad, the contact angle of the pure water on the surface of the surface of the polishing wafer with respect to pure water is a polishing pad that is 58 degrees or more and 70 degrees or less after 1800 seconds after the pure water is dropped. For example, the single-side polishing method for wafers in claim 1, characterized in that: Among them, as the above-mentioned polishing pad, a polishing pad that does not use a single raised layer of a non-woven fabric is used. For example, the single-side polishing method for wafers in claim 2, which is characterized in that: Among them, as the above-mentioned polishing pad, a polishing pad that does not use a single raised layer of a non-woven fabric is used. For example, the single-side polishing method for wafers in claim 3, which is characterized in that: Among them, as the above-mentioned polishing pad, a polishing pad that does not use a single raised layer of a non-woven fabric is used. For example, the single-side polishing method for wafers in claim 4 is characterized in that: Among them, as the above-mentioned polishing pad, a polishing pad that does not use a single raised layer of a non-woven fabric is used. For example, the single-side polishing method for a wafer according to any one of claims 1 to 8, characterized in that: Among them, to maintain the inner diameter of the retainer of the wafer, the ratio of the inner diameter of the retainer to the diameter of the wafer is as follows: Retainer inner diameter/wafer diameter=1.0015 or more and 1.0067 or less Represents the guard ring. For example, the single-side polishing method for a wafer according to any one of claims 1 to 8, characterized in that: Among them, the number of rotations of the above-mentioned table during grinding is set at 15 rpm or more and 80 rpm or less. The single-side polishing method for a wafer according to any one of claims 1 to 8, wherein the polishing pressure is set at 100 g/cm ² or more and 300 g/cm ² or less. For example, the single-side polishing method for a wafer according to any one of claims 1 to 8, characterized in that: The relationship between the polishing conditions and the wafer rotation rate is determined in advance, and the polishing conditions are determined based on the above relationship. For example, the single-side polishing method for wafers in claim 12 is characterized in that: Wherein, the above-mentioned polishing conditions are any one or a combination of the compressibility of the polishing pad, the contact angle, the ratio of the inner diameter of the guard ring to the above-mentioned wafer diameter, the number of rotations of the polishing table, and the amount of polishing pressure. A method for manufacturing a wafer, characterized in that: include: Complete the single-sided finishing step of at least one side of the above-mentioned wafer; In the above-mentioned single-side finishing step, a polishing process is performed on the polished surface of the wafer by the single-side polishing method of any one of claims 1-13. A single-side polishing device for wafers, characterized in that: include: The head rotating shaft member is provided with a polishing head for holding the above-mentioned wafer; Platform, fix the polishing pad to the surface; Head driving means, driving the above-mentioned head rotating shaft member; Platform driving means to drive the above-mentioned platforms; Wafer pressure adjustment means to adjust the pressure for pressing the wafer to the polishing pad; and The grinding condition determination department determines the grinding conditions; Among them, the above-mentioned polishing condition determination unit determines the polishing conditions such that the rotation rate of the wafer is 25 degrees/min or more and 60 degrees/min or less.

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