JP2021106193A - Soi wafer single side polishing system and soi wafer single side polishing method using the same - Google Patents

Abstract

To provide an SOI wafer single side polishing system and an SOI wafer single side polishing method using the same that are capable of further making a film thickness distribution of an SOI layer uniform.SOLUTION: A single side polishing system comprises a surface plate, a polishing pad, a polishing head, a polishing head drive mechanism, an optical film thickness measurement unit, a control unit, and a storage unit. The control unit moves an SOI wafer held on the polishing head to a position over a window part of the surface plate by using the polishing head drive mechanism and, via the window part, measures a film thickness distribution in at least a radial direction of an SOI layer of the SOI wafer by the optical film thickness measurement unit and stores the film thickness distribution in the storage unit; on the basis of the film thickness distribution stored in the storage unit, determines an execution pressurization distribution for making the film thickness distribution uniform and sets the execution pressurization distribution as a pressurization distribution for the polishing head; and polishes a surface of the SOI layer of the SOI wafer held on the polishing head.SELECTED DRAWING: Figure 1

Description

The present invention relates to a single-sided polishing system for SOI wafers and a single-sided polishing method for SOI wafers using the same.

In recent years, SOI wafers having an SOI (Silicon on Insulator) structure have attracted attention in various semiconductor device applications such as highly integrated CMOS elements, high withstand voltage elements, and image sensors.

_{In a SOI wafer, generally, a semiconductor layer such as an insulating layer such as silicon oxide (SiO 2} ) and a single crystal silicon layer used as a device active layer are sequentially formed on a support substrate wafer made of a single crystal silicon wafer. Has a structure. In addition, this semiconductor layer is also called an active layer or an SOI layer, and is hereinafter referred to as an "SOI layer" in the present specification. In a bulk single crystal silicon wafer, the parasitic capacitance that can be generated between the element and the substrate portion is relatively large, but since the SOI layer is provided on the insulating layer, the parasitic capacitance can be significantly reduced. Therefore, the SOI wafer is advantageous in terms of speeding up the device, increasing the withstand voltage, reducing the power consumption, and the like.

High integration of semiconductor devices is accelerating, and improvement of surface quality such as flatness of semiconductor wafers is required. In order to meet this demand, a wide range of improvements have been made to the polishing apparatus and polishing method for semiconductor wafers.

For example, in the semiconductor wafer polishing apparatus described in Patent Document 1, a polishing head provided with a plurality of pressure chambers is used in order to prevent deformation of the semiconductor wafer due to polishing pressure.

Further, in Patent Document 2, the film thickness distribution in the circumferential direction of the semiconductor wafer is acquired, the first region is determined based on the film thickness distribution in the circumferential direction, and the platen to which the polishing pad is attached is rotated. While rotating the semiconductor wafer with the polishing head, the surface of the semiconductor wafer is pressed against the polishing pad, and the first region is polished at a removal rate different from the removal rate of the second region in the surface of the semiconductor wafer. The polishing method is disclosed. In the polishing method described in Patent Document 2, the film thickness distribution in the circumferential direction is measured by using a film thickness sensor provided on the surface plate while utilizing the rotation of the surface plate and the polishing head. This is an attempt to eliminate variations in the film thickness distribution by polishing.

Further, particularly in the case of an SOI wafer, excellent film thickness uniformity of the SOI layer is also required, and improvement of a polishing method specialized for the SOI wafer is also attempted (see, for example, Patent Documents 3 and 4).

Japanese Unexamined Patent Publication No. 2009-131920 Japanese Unexamined Patent Publication No. 2017-64801 Japanese Unexamined Patent Publication No. 2014-63894 Japanese Unexamined Patent Publication No. 2014-63878

By the way, the film thickness distribution of the SOI layer of the SOI wafer is easily affected by the uneven shape of the support substrate wafer and the manufacturing process before polishing. As described in Patent Documents 3 and 4, the film thickness distribution may vary in a taper shape in a specific direction, but it may also vary in the radial direction. Further, in the SOI wafer, as described above, the uniform film thickness of the SOI layer is required, and even if the variation in the thickness distribution of the entire SOI wafer is partially sacrificed, it is necessary to give priority to the uniform film thickness of the SOI layer. There is. The polishing method disclosed in Patent Document 2 referred to above is intended to eliminate variations in the circumferential film thickness distribution of the entire semiconductor wafer. Therefore, in order to make the film thickness distribution of the SOI layer of the SOI wafer more uniform, the polishing method cannot be applied as it is.

Therefore, an object of the present invention is to provide a single-sided polishing system for SOI wafers capable of making the thickness distribution of the SOI layer more uniform, and a single-sided polishing method for SOI wafers using the same.

The present inventors have diligently studied to solve the above problems. Then, the film thickness distribution of the SOI layer in at least the radial direction is measured prior to polishing through the window portion provided on the surface plate, and the pressurization distribution of the pressurization control chamber in the polishing head is measured based on the measurement result. The present inventors have found that the film thickness distribution of the SOI layer can be made uniform if properly controlled. The abstract structure of the present invention completed based on the above findings is as follows.

(1) Polishing the surface of the SOI layer of an SOI wafer having a support substrate wafer, an insulating layer provided on one surface of the support substrate wafer, and an SOI layer provided on the surface of the insulating layer. A single-sided polishing system for SOI wafers
The single-sided polishing system includes a surface plate, a polishing pad, a polishing head, a polishing head drive mechanism, an optical film thickness measuring unit, a control unit, and a storage unit.
The surface plate has a window portion and has a window portion.
The polishing pad is attached to one side of the surface plate and is attached.
The polishing head has a head main body and a backing plate provided at the center of the lower surface of the head main body and capable of adsorbing the other surface of the support substrate wafer, and the head main body is via the backing plate. It is equipped with a pressurization control chamber that can set the pressurization distribution in each of multiple radial regions.
The polishing head drive mechanism can be connected to the polishing head to translate and rotate the polishing head.
The control unit
(I) Using the polishing head drive mechanism, the SOI wafer held by the polishing head is moved onto the window portion of the surface plate, and the optical film thickness measurement is performed through the window portion. The film thickness distribution in at least the radial direction of the SOI layer was measured by the unit, and the film thickness distribution was recorded in the storage unit.
(Ii) Based on the film thickness distribution recorded in the storage unit, an execution pressure distribution for making the film thickness distribution uniform is determined.
(Iii) The pressure distribution for execution is set to the pressure distribution in the pressure control chamber.
(Iv) A single-sided polishing system for an SOI wafer, characterized in that the surface of the SOI layer of the SOI wafer held by the polishing head is rubbed against the polishing pad to be polished.

(2) The single-sided polishing system for an SOI wafer according to (1), wherein the control unit (i) measures the film thickness distribution on the entire surface of the SOI layer.

(3) The single-sided polishing system for the SOI wafer further includes a slurry supply nozzle capable of supplying a polishing slurry to the surface of the polishing pad.
The control unit (iv) polishes the surface of the SOI layer while supplying the polishing slurry from the slurry supply nozzle to the polishing pad, and single-sided polishing of the SOI wafer according to (1) or (2). system.

(4) The optical film thickness measuring unit includes a light source capable of incident measurement light through the window unit and a light receiving sensor capable of receiving reflected light of the measurement light.
The single-sided polishing system for an SOI wafer according to any one of (1) to (3) above, wherein the control unit (i) incidents the measurement light when the SOI wafer is located on the window portion.

(5) Single-sided polishing of an SOI wafer, which comprises single-sided polishing of the SOI layer of the SOI wafer using the single-sided polishing system for the SOI wafer according to any one of (1) to (4). Method.

According to the present invention, it is possible to provide a single-sided polishing system for an SOI wafer capable of making the thickness distribution of the SOI layer more uniform, and a single-sided polishing method for an SOI wafer using the system.

It is a schematic diagram of the single-sided polishing system of the SOI wafer according to one Embodiment of this invention. It is an enlarged view in the single-sided polishing system of the SOI wafer according to one Embodiment of this invention. It is a schematic plan view of the pressure control chamber in the single-sided polishing system of the SOI wafer according to one Embodiment of this invention. (A) and (B) are schematic views of the pressure distribution in the single-sided polishing system of the SOI wafer according to the embodiment of the present invention, respectively. Each of (A) and (B) is an example of a polishing allowance obtained by polishing using a single-sided polishing system for an SOI wafer according to an embodiment of the present invention. It is a radial film thickness distribution of the SOI layer before and after polishing measured in Example 1. It is a graph which shows the fluctuation width of the film thickness of the SOI layer measured in Example 1 and Comparative Example 1, (A) shows before polishing, (B) shows after polishing.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In principle, the same components are given the same reference number, and duplicate explanations are omitted. Further, each configuration shown in FIGS. 1 to 4 is a schematic view and is different from the actual aspect ratio. Note that FIG. 2 is an enlarged schematic view illustrating a state in which the SOI wafer 10 schematically shown in FIG. 1 is held by the polishing head 40 and the SOI wafer 10 is located on the window portion 21 of the surface plate 20. Is.

(Single-sided polishing system for SOI wafers)
See FIGS. 1 and 2. The objects to be polished by the single-sided polishing system 100 of the SOI wafer according to the embodiment of the present invention are provided on the surface of the support substrate wafer 11, the insulating layer 12 provided on one surface of the support substrate wafer 11, and the surface of the insulating layer 12. This is the surface of the SOI layer 13 of the SOI wafer 10 having the SOI layer 13. The single-sided polishing system 100 (hereinafter, "single-sided polishing system 100") of this SOI wafer includes a surface plate 20, a polishing pad 30, a polishing head 40, a polishing head drive mechanism 50, and an optical film thickness measuring unit. 60, a control unit 70, and a storage unit 80 are provided at least. Then, the film thickness distribution of the SOI layer 13 in at least the radial direction is measured by the optical film thickness measuring unit 60 via the control unit 70, and the pressure distribution on the SOI wafer 10 by the polishing head 40 is controlled based on this. The surface of the SOI layer 13 is polished. By doing so, the film thickness distribution of the SOI layer can be made uniform. Hereinafter, details of each configuration will be described in sequence.

<Surface plate>
The single-sided polishing system 100 includes a surface plate 20. The surface plate 20 has a window portion 21. A surface plate used in a general single-sided polishing apparatus for a semiconductor wafer can be applied to the surface plate 20 of the single-sided polishing system 100. The position of the window portion 21 on the surface plate 20 is not particularly limited as long as it can scan at least the entire diameter of the SOI wafer 10 by moving the polishing head 40 by the polishing head drive mechanism 50. Through the window portion 21, the optical film thickness measuring unit 60 measures the film thickness of the SOI layer 13 of the SOI wafer 10. The size and shape of the window portion 21 are not particularly limited as long as they can be measured by the optical film thickness measuring unit 60. The window portion 21 may be a through hole, or may be made of a transparent member capable of transmitting 60 L of measurement light such as visible light or infrared light. Further, as shown in FIG. 1, the surface plate 20 is generally provided with a rotating shaft 25 on the lower surface of the surface plate 20, and the surface plate 20 can be rotated by the rotation of the rotating shaft 25.

<Polishing pad>
The single-sided polishing system 100 includes a polishing pad 30. The polishing pad 30 is attached to one side of the surface plate 20. The polishing pad 30 is processed with a hole that matches the window portion 21, and the hole may be aligned with the position of the window portion 21 for attachment. Further, for example, a polishing pad used in a general single-sided polishing apparatus for a semiconductor wafer, such as a pad made of a non-woven fabric made of polyester or a pad made of polyurethane, can be applied to the polishing pad 30.

<Polishing head>
Particular reference is made to FIG. The single-sided polishing system 100 includes a polishing head 40, and the SOI wafer 10 can be held by the polishing head 40. The polishing head 40 is provided at the center of the lower surface of the head main body 41 and the head main body 41, and is backing capable of adsorbing the other surface of the support substrate wafer 11 (that is, the surface opposite to the insulating layer 12). It has a plate 43. The backing plate 43 is generally provided with an elastic body such as a permeable porous foamed resin pad or membrane rubber. The chucking method of the backing plate 43 is arbitrary, such as an adsorption method using surface tension using a liquid such as water and a vacuum chucking method.

Further, the polishing head 40 may be provided with a retainer ring 47 for preventing the SOI wafer 10 from popping out during polishing. In FIGS. 1 and 2, the retainer ring 47 is provided on the lower peripheral edge of the head main body 41, but this is only an example. The retainer ring (also referred to as a guide ring or template) used for the polishing head of a general semiconductor wafer single-sided polishing apparatus can be applied to the retainer ring 47.

<< Pressurization control room >>
The head main body 41 is provided with a pressure control chamber 45 (45A, 45B, 45C, 45D) capable of setting a pressure distribution in each of a plurality of radial regions via the backing plate 43 (see FIG. 2). ). A schematic plan view of the pressurization control chamber 45 is shown in FIG. Note that, in FIGS. 2 and 3, the case where the pressure control chambers 45A, 45B, 45C, and 45D arranged symmetrically in the radial direction constitute the pressurization control chamber 45 is illustrated, but this is only an example. It is possible to set the pressure distribution if there are two or more pressure control chambers. The pressure control chambers 45A, 45B, 45C, and 45D can be classified by a partition membrane or the like, and the pressure applied to each pressure control chamber can be controlled by a fluid such as pressurized air. 4 (A) and 4 (B) show an example of the pressure distribution by the pressure control chamber 45. In FIG. 4A, in order to increase the polishing allowance of the peripheral portion (edge portion) of the SOI wafer 10, the pressure applied to the central portion of the SOI wafer 10 is reduced and the pressure applied to the peripheral portion of the SOI wafer 10 is increased. The pressure distribution when the pressure is increased is schematically shown. The arrow in the figure means the pressing force. Further, in FIG. 4B, contrary to the case of FIG. 4A, in order to increase the polishing allowance in the central portion of the SOI wafer 10, the pressure in the central portion of the SOI wafer 10 is increased and the pressure in the central portion of the SOI wafer 10 is increased. The pressure distribution when the pressure on the peripheral edge of the SOI wafer 10 is reduced is schematically shown.

<Polishing head drive mechanism>
Return to FIG. The single-sided polishing system 100 includes a polishing head drive mechanism 50, and the polishing head drive mechanism 50 is connected to the polishing head 40 to translate and rotate the polishing head 40. It is used for various purposes such as holding the SOI wafer 10, measuring the film thickness distribution of the SOI layer 13 on the SOI wafer 10, polishing the SOI layer 13, and the like, and is used for one side of a general semiconductor wafer. The polishing head drive mechanism of the polishing apparatus can be used.

<Optical film thickness measuring unit>
The single-sided polishing system 100 includes an optical film thickness measuring unit 60. The thickness of the SOI layer 13 is not particularly limited as long as it can be measured, but the optical film thickness measuring unit 60 is, for example, a light source 61 capable of incident measurement light 60L and a light receiving light capable of receiving reflected light of the measurement light 60L. It can have a sensor 62 (see FIG. 2). An example of a measurement mode when measuring the film thickness of the SOI layer 13 of the portion located on the window portion 21 will be described. The incident light of the measurement light 60L from the light source 61 is collected by the lens 65 via the optical fiber 63, and the measurement light 60L is collected through the window portion 21 of the platen 20 on the exposed surface of the SOI layer 13 of the SOI wafer 10. Incident in. The measurement light 60L is reflected by the insulating layer 12, and after passing through the lens 65 and the optical fiber 63, the light receiving sensor 62 receives the reflected light of the measurement light 60L. In this way, the film thickness of the SOI layer 13 can be obtained. After moving the SOI wafer 10 by the polishing head drive mechanism 50, the film thickness distribution of the SOI layer 13 can be obtained by performing the same measurement by the optical film thickness measuring unit 60. The wavelength of the light source 61 is, for example, a visible light region and may be an infrared light region.

<Control unit>
The single-sided polishing system 100 includes a control unit 70. The control unit 70 may include one or more processors, and can be realized by a microprocessor or the like. The control unit 70 controls the operation of the entire single-side polishing system 100, and the specific control process will be described later.

<Memory>
The single-sided polishing system 100 includes a storage unit 80, and the storage unit 80 may include one or more memories. A main storage device, an auxiliary storage device, a cache memory, or the like can be used for each memory that can be included in the storage unit 80.

<Control process>
The control process by the control unit 70 using each configuration of the single-sided polishing system 100 described above will be described. Roughly speaking, the control unit 70 (i) measures and records the film thickness distribution of the SOI layer 13, (ii) determines the pressure distribution for execution based on the measured film thickness distribution, and (iii) determines. The pressure distribution for execution is set to the pressure distribution of the pressure control chamber 45, and (iv) the SOI layer 13 is polished using this pressure distribution.

<< (i) Film thickness distribution measurement >>
First, the control unit 70 uses the polishing head drive mechanism 50 to move the SOI wafer 10 held by the polishing head 40 onto the window portion 21 of the surface plate 20. Then, the film thickness of the SOI layer 13 located on the window portion 21 is measured by the optical film thickness measuring unit 60 via the window portion 21. When the SOI wafer 10 is located on the window portion 21, the control unit 70 may make the measurement light 60L incident on the SOI layer 13 from the optical film thickness measuring unit 60. Then, the SOI wafer 10 is moved together with the polishing head 40 by using the polishing head drive mechanism 50, and the film thickness measurement is repeated to measure the film thickness distribution of the SOI layer 13 in at least the radial direction. Then, the control unit 70 records the measured film thickness distribution in the storage unit 80. It is also preferable to measure the film thickness distribution on the entire surface of the SOI layer 13. In this case, it is preferable to average the film thickness of the SOI layer 13 in the circumferential direction and reflect it in the pressure distribution in the radial direction.

<< (ii) Determination of pressure distribution for execution >>
Next, the control unit 70 determines the execution pressure distribution used for polishing to make the film thickness distribution uniform, based on the film thickness distribution recorded in the storage unit 80. The control unit 70 may select the execution pressure distribution from the pressure distribution candidate group stored in advance in the storage unit 80. Further, the control unit 70 may calculate the execution pressure distribution from the film thickness distribution recorded in the storage unit 80 so that the film thickness variation in the radial direction is eliminated. In either case, the pressure applied to the portion where the film thickness is larger than the average film thickness of the film thickness distribution based on the measurement result is increased, and the pressure applied to the portion whose film thickness is smaller than the average film thickness is decreased. The distribution may be adopted.

<< (iii) Pressurization distribution setting >>
After that, the control unit 70 sets the pressure distribution for execution to the pressure distribution of the pressure control chamber 45. For example, the pressure in each pressure control chamber of the pressurization control chamber 45 may correspond to the pressure distribution for execution.

<< (iv) polishing >>
Then, the control unit 70 rubs the surface of the SOI layer 13 of the SOI wafer 10 held by the polishing head 40 against the polishing pad 30 to polish it. Generally, as in FIG. 1, the rotation direction of the polishing head 40 and the rotation direction of the surface plate are the same. It is also preferable to swing the polishing head 40 during polishing.

In the single-sided polishing system 100 described so far, the film thickness distribution of the SOI layer 13 in at least the radial direction is measured by the optical film thickness measuring unit 60 via the control unit 70. Then, based on this measurement result, the pressure distribution on the SOI wafer 10 by the polishing head 40 is controlled to polish the surface of the SOI layer 13. Therefore, in single-sided polishing using the single-sided polishing system 100, the film thickness of the SOI layer 13 is set in order to set the pressure distribution to eliminate the variation in the film thickness distribution in the radial direction of the SOI layer 13. The distribution can be made more uniform. Further, using this single-sided polishing system 100 is also advantageous in that the film thickness distribution of the SOI layer 13 before polishing can be measured without excessively increasing the number of steps. The average film thickness of the SOI layer 13 before polishing is thinned to approximately 10 μm to 100 μm, and when the film thickness of the SOI layer 13 is measured using a separate film thickness measuring device, it is affected by the stage of the film thickness measuring device. Cheap. However, if the single-sided polishing system 100 is used, the film thickness can be measured and polished while the SOI wafer 10 is mounted on the polishing head 40, so that a measurement error due to the influence of the stage can be eliminated.

<Slurry supply nozzle>
As shown in FIG. 1, it is also preferable that the single-sided polishing system 100 further includes a slurry supply nozzle 90 capable of supplying the polishing slurry 91 to the surface of the polishing pad 30. An alkaline aqueous solution or the like containing free abrasive grains can be used for the polishing slurry 91. This is because chemical mechanical polishing (CMP) can be performed by supplying the polishing slurry 91 during the polishing of the SOI layer 13. In this case, the control unit 70 may polish the surface of the SOI layer 13 while supplying the polishing slurry 91 from the (iv) slurry supply nozzle 90 to the polishing pad 30. However, in order to accurately measure the film thickness distribution of the SOI layer 13, in the case of (i) film thickness distribution measurement, the control unit 70 does not supply the polishing slurry 91 and closes the slurry supply nozzle 90. Is preferable.

<SOI wafer>
As described above, the SOI wafer 10 to be polished by the single-sided polishing system 100 is provided on the surface of the support substrate wafer 11, the insulating layer 12 provided on one surface of the support substrate wafer 11, and the surface of the insulating layer 12. It has an SOI layer 13. It is preferable to apply the single-sided polishing system 100 to the polishing of the SOI wafer in which the radial variation is larger than the circumferential variation. However, even if the circumferential variation is larger than the radial variation, there is virtually no SOI wafer with no radial variation in the state before polishing, and the effect of the single-sided polishing system 100 is not lost. The total thickness of the SOI wafer before polishing is about 700 to 1200 μm. Hereinafter, specific embodiments of the SOI wafer 10 will be described. However, it is naturally understood that the present invention is not limited to the following specific examples.

<< Support substrate wafer >>
A single crystal silicon wafer made of a silicon single crystal can be used for the support substrate wafer 11. As the single crystal silicon wafer, one obtained by slicing a single crystal silicon ingot grown by a Czochralski method (CZ method), a floating zone melting method (FZ method) or the like with a wire saw or the like can be used. Further, carbon and / or nitrogen may be added to the single crystal silicon wafer. Further, any impurities may be added to obtain n-type or p-type.

<< Insulation layer >>
The insulating layer 12 can be formed on the surface of the support substrate wafer 11 by performing heat treatment in an oxidizing atmosphere or the like. Further, the insulating layer 12 is not limited to silicon oxide formed by heat treatment, and various electric insulators can be used. For example, silicon nitride may be used, or diamond-like carbon (DLC) may be used. Etc. can also be used. The film thickness of the insulating layer 12 is not limited, but is generally 0.1 μm to 5 μm.

<< SOI layer >>
The SOI layer 13 is a thin film obtained by bonding a single crystal silicon wafer made of a silicon single crystal to a support substrate wafer 11 via an insulating layer 12 and then grinding the wafer. The support substrate wafer and the conductive type (p type and n type) may be aligned or different.

(Single-sided polishing method for SOI wafers)
Further, in the single-sided polishing method of the SOI wafer according to the embodiment of the present invention, the SOI layer 13 of the SOI wafer 10 is single-sided polished by using the single-sided polishing system 100 of the SOI wafer described above. In this single-sided polishing method, a step of measuring the film thickness distribution of the SOI layer 13, a step of determining the execution pressure distribution based on the measured film thickness distribution, and a step of determining the execution pressure distribution are determined in the pressurization control room. A step of setting the pressure distribution of 45 and a step of polishing the SOI layer 13 using this pressure distribution can be included. By this single-sided polishing method, the film thickness distribution of the SOI layer 13 can be made more uniform.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples.

(Example 1)
Single-sided polishing of one SOI wafer was performed using the single-sided polishing system 100 of the SOI wafer described above. First, the film thickness distribution on the entire surface of the SOI layer 13 is measured, and the execution pressure distribution is selected from the pressure distribution candidate group stored in advance in the storage unit 80 based on the measurement result, and the SOI layer 13 is selected. One side was CMP polished. An example of the polishing allowance distribution obtained when the pressure distribution candidate group stored in the storage unit 80 is selected is shown in FIGS. 5 (A) and 5 (B). FIG. 5A shows a radial polishing allowance distribution obtained from a pressure distribution candidate group selected when the film thickness of the central portion is about 0.1 μm thinner than that of the peripheral portion in the film thickness distribution of the SOI layer 13. Is. Further, FIG. 5B shows a radial polishing allowance obtained from the pressure distribution candidate group selected when the film thickness of the central portion is 0.2 μm thicker than that of the peripheral portion in the film thickness distribution of the SOI layer 13. It is a distribution. The number of pressure control chambers in the pressurization control chamber 45 is four as in FIG. 2 and the like illustrated as an example, and the pressure distribution can be set in the radial direction.

FIG. 6 shows the radial film thickness distribution before and after performing single-sided polishing according to Example 1. In the film thickness distribution before polishing, the film thickness at the central portion was about 0.2 μm larger than that at the peripheral portion, so a pressure distribution was adopted to obtain the polishing allowance distribution shown in the graph of FIG. 5 (B). did. From FIG. 6, it is confirmed that the film thickness distribution of the SOI layer after polishing can be made uniform.

(Comparative Example 1)
One side of the SOI layer 13 was CMP-polished so that the overall thickness distribution of the SOI wafer 10 was uniform without measuring the film thickness distribution of the SOI layer 13. The apparatus configuration is the same as that of the first embodiment except for the control method including the film thickness distribution measurement and the pressure distribution control.

The graphs of FIGS. 7 (A) and 7 (B) show the fluctuation range of the film thickness of the SOI layer measured in Example 1 and Comparative Example 1. It should be noted that these graphs are plots of the measured values of the film thickness on the entire surface of each of the SOI wafers of Example 1 and Comparative Example 1 for each point, and are the measured values obtained from one SOI wafer. .. FIG. 7A shows the fluctuation range of the film thickness distribution before polishing, and FIG. 7B shows the fluctuation range of the film thickness after polishing. Due to the difference in lots, the fluctuation range of the film thickness of the SOI layer before polishing is smaller in Comparative Example 1. Despite these circumstances, when the fluctuation range of the film thickness distribution of the SOI layer after polishing is compared between Example 1 and Comparative Example 1, the variation range of the film thickness is smaller in Example 1. It was confirmed that the film thickness accuracy was significantly improved. The standard deviation in the fluctuation range of the film thickness of the SOI layer was 0.014 μm in Example 1 and 0.032 μm in Comparative Example 1.

According to the present invention, it is possible to provide a single-sided polishing system for an SOI wafer capable of making the thickness distribution of the SOI layer more uniform, and a single-sided polishing method for an SOI wafer using the system.

10 SOI wafer 20 Surface plate 21 Window part 30 Polishing pad 40 Polishing head 41 Head body part 43 Backing plate 45 Pressurization control room 50 Polishing head drive mechanism 60 Optical film thickness measuring unit 70 Control unit 80 Storage unit 90 Slurry supply nozzle 91 Polishing Slurry 100 Single-sided polishing system for SOI wafers

Claims (5)

An SOI wafer for polishing the surface of an SOI layer of an SOI wafer having a support substrate wafer, an insulating layer provided on one surface of the support substrate wafer, and an SOI layer provided on the surface of the insulating layer. It is a single-sided polishing system
The single-sided polishing system includes a surface plate, a polishing pad, a polishing head, a polishing head drive mechanism, an optical film thickness measuring unit, a control unit, and a storage unit.
The surface plate has a window portion and has a window portion.
The polishing pad is attached to one side of the surface plate and is attached.
The polishing head has a head main body and a backing plate provided at the center of the lower surface of the head main body and capable of adsorbing the other surface of the support substrate wafer, and the head main body is via the backing plate. It is equipped with a pressurization control chamber that can set the pressurization distribution in each of multiple radial regions.
The polishing head drive mechanism can be connected to the polishing head to translate and rotate the polishing head.
The control unit
(I) Using the polishing head drive mechanism, the SOI wafer held by the polishing head is moved onto the window portion of the surface plate, and the optical film thickness measurement is performed through the window portion. The film thickness distribution in at least the radial direction of the SOI layer was measured by the unit, and the film thickness distribution was recorded in the storage unit.
(Ii) Based on the film thickness distribution recorded in the storage unit, an execution pressure distribution for making the film thickness distribution uniform is determined.
(Iii) The pressure distribution for execution is set to the pressure distribution in the pressure control chamber.
(Iv) A single-sided polishing system for an SOI wafer, characterized in that the surface of the SOI layer of the SOI wafer held by the polishing head is rubbed against the polishing pad to be polished. The single-sided polishing system for an SOI wafer according to claim 1, wherein the control unit (i) measures the film thickness distribution on the entire surface of the SOI layer. The single-sided polishing system for an SOI wafer further includes a slurry supply nozzle capable of supplying a polishing slurry to the surface of the polishing pad.
The single-sided polishing system for an SOI wafer according to claim 1 or 2, wherein the control unit (iv) polishes the surface of the SOI layer while supplying the polishing slurry from the slurry supply nozzle to the polishing pad. The optical film thickness measuring unit includes a light source capable of incident measurement light through the window unit and a light receiving sensor capable of receiving reflected light of the measurement light.
The single-sided polishing system for an SOI wafer according to any one of claims 1 to 3, wherein the control unit (i) incidents the measurement light when the SOI wafer is located on the window portion. A method for single-sided polishing of an SOI wafer, which comprises single-sided polishing of the SOI layer of the SOI wafer using the single-sided polishing system for the SOI wafer according to any one of claims 1 to 4.

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