JP2006263876A - Polishing device, polishing method, and manufacturing method for semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide polishing device and polishing method for realizing high flattening, and a manufacturing method for a semiconductor device by using the polishing method. <P>SOLUTION: This polishing device 4 has a polishing surface plate 8, polishing cloth 7 mounted on the polishing surface plate 8 to polish a wafer 17, a dresser 9 for dressing the surface of the polishing cloth 7 and an inclined angle measuring means 10 for measuring an inclined angle of the surface of the polishing cloth 7. The inclined angle measuring means 10 may have a film thickness measuring part 13 for measuring film thickness of the polishing cloth 7 and an inclined angle calculating part 14 for calculating the inclined angle from the film thickness. The film thickness measuring part 13 may have an eddy current sensor 15. It is desirable that a dressing condition control part 11 for controlling the condition of dressing according to the inclined angle is connected to the inclined angle measuring means 10 and the part 11 is a mechanism for transmitting control data to the dresser 9. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a polishing apparatus, a polishing method, and a method for manufacturing a semiconductor device.

  The manufacturing process of a semiconductor device includes a process of forming a conductor film on a semiconductor wafer to form a wiring layer, and a process of forming an interlayer insulating film on the wiring layer. In these steps, unevenness is generated on the surface of the semiconductor wafer, so that a technique for flattening the surface is important.

  Conventionally, there is a chemical mechanical polishing method as a technique for flattening the unevenness of the surface. The chemical mechanical polishing method is a technique in which polishing is performed using an abrasive (slurry) in which abrasive grains are dispersed in a liquid while the surface of a semiconductor wafer is pressed against a polishing surface. Hereinafter, a polishing method using a conventional chemical mechanical polishing apparatus will be described.

  A conventional chemical mechanical polishing apparatus includes a polishing surface plate having a polishing cloth attached to the upper surface, a holding table for holding a semiconductor wafer to be polished, and a dresser for roughening the surface of the polishing cloth. For example, before polishing, first, dressing (also referred to as conditioning. The same applies in this specification) is performed in which the surface of the polishing cloth is fluffed with a dresser. Next, the semiconductor wafer is held by the holding table so that the surface to be polished faces the polishing cloth, and then the holding table is lowered onto the polishing surface plate. Then, polishing is performed by rotating both the polishing surface plate and the holding table in a state where the surface to be polished is pressed against the polishing cloth while dropping the polishing agent on the polishing cloth.

  In the polishing process using such a chemical mechanical polishing method, by making the in-plane polishing rate uniform, surface irregularities can be eliminated and high flatness can be realized.

  Here, the polishing rate has been conventionally controlled by adjusting the pressing pressure of the surface to be polished, the rotational speed of the holding table, the rotational speed of the polishing surface plate, and the flow rate of the abrasive. For example, by controlling the inclination angle of the polishing surface plate by electromagnetic force, there has been proposed a method for eliminating the undulation of the polishing cloth caused by the rotation of the polishing surface plate and making the pressing pressure of the surface to be polished uniform (for example, (See Patent Document 1). However, there is a problem that such a method has a limit and cannot be sufficiently flattened.

JP 2000-317824 A

  The present invention has been made in view of such problems. That is, an object of the present invention is to provide a polishing apparatus that can realize high planarization.

  Moreover, the objective of this invention is providing the grinding | polishing method which can implement | achieve high planarization.

  Furthermore, an object of the present invention is to provide a semiconductor device manufacturing method using a polishing method capable of realizing high planarization.

  Other objects and advantages of the present invention will become apparent from the following description.

  The first invention of the present application provides a polishing surface plate, a polishing cloth attached to the polishing surface plate for polishing a member to be polished, a dresser for dressing the surface of the polishing cloth, and an inclination angle of the surface of the polishing cloth. The present invention relates to a polishing apparatus having an inclination angle measuring means for measuring.

  The second invention of the present application includes a step of polishing the surface of the wafer while rotating the polishing surface plate and the wafer in a state where the wafer is pressed against the polishing cloth attached to the polishing surface plate, A step of obtaining an inclination angle, a step of creating control data regarding dressing conditions from the inclination angle, and a step of dressing the polishing cloth while rotating the polishing platen and the dresser according to the control data. The present invention relates to a polishing method.

  Furthermore, a third invention of the present application has a step of forming a film to be processed on a semiconductor wafer and a step of polishing the film to be processed by the polishing method of the present invention. About.

  According to the present invention, the in-plane film thickness uniformity of the polishing cloth can be improved by measuring the inclination angle of the polishing cloth and optimizing the dressing conditions in accordance with the result. High flatness can be realized by reducing in-plane variation of the polishing rate with respect to the surface.

  As described above, dressing is performed on the polishing cloth before the polishing process by the chemical mechanical polishing method. This is intended to prevent the polishing rate from being lowered by the surface of the polishing cloth being smoothed by polishing.

  As shown in FIG. 1, dressing is performed by pressing a dresser 3 to which diamond particles are adhered against a polishing cloth 2 attached to a polishing surface plate 1, and rotating the polishing surface plate 1 and the dresser 3 together in this state. By performing dressing, the polishing cloth can hold the abrasive well, so that the polishing rate can be recovered and the polishing efficiency can be improved.

  As a result of intensive studies, the present inventor has found that there is a correlation between the inclination angle θ of the polishing pad after dressing and the in-plane variation of the polishing rate. An example is shown in FIG.

  In FIG. 2, the in-plane variation of the polishing rate is minimized when the inclination angle is about −0.0025 degrees, but the variation gradually increases as the inclination angle becomes larger or smaller than this.

  Specifically, when the inclination angle increases to the plus side, the film thickness of the polishing pad 2 increases toward the outer peripheral portion (FIG. 3A). On the other hand, when the inclination angle increases toward the minus side, the film thickness of the polishing pad 2 decreases toward the outer periphery (FIG. 3B). For this reason, when polishing with the polishing cloth in the state of FIG. 3A, the pressure applied to the surface to be polished of the wafer increases toward the outer peripheral portion, so that the polishing rate increases at the outer peripheral portion. On the other hand, when polishing is performed with the polishing cloth in the state of FIG. 3B, the pressure applied to the surface to be polished of the semiconductor wafer becomes smaller toward the outer peripheral portion, so that the polishing rate becomes slower at the outer peripheral portion.

  FIG. 4 is a diagram showing variations in the polishing rate within the wafer surface. In FIG. 4, “a” corresponds to the case of polishing with a polishing cloth having an inclination angle of −0.0103 degrees (measurement point a) in FIG. 2. In addition, “b” corresponds to the case of polishing with a polishing cloth having an inclination angle of +0.0014 degrees (measurement point B) in FIG.

  From the above, the inventor can improve the in-plane film thickness uniformity of the polishing cloth by measuring the inclination angle of the polishing cloth and optimizing the dressing conditions according to the result. The inventors have considered that it is possible to reduce in-plane variation in the polishing rate with respect to the surface to be polished, and have reached the present invention.

Here, the in-plane film thickness uniformity of the polishing cloth is obtained as follows. That is, the film thickness of the polishing cloth is measured at a plurality of predetermined locations. Then, assuming that the maximum value of the film thickness is t _max , the minimum value is t _min , and the average value is t _ave , the in-plane film thickness uniformity (%) = {(t _max −t _min ) / 2t _ave } × 100 A relationship is established.

  On the other hand, the polishing rate is obtained as follows. That is, the film thickness at a predetermined portion of the polishing cloth is measured before and after polishing, and the average value of the amount of decrease in film thickness at each portion is calculated. A value obtained by dividing the average value by the polishing time is the polishing rate.

  FIG. 5 is a plan view of the polishing apparatus in the present embodiment. As a wafer applicable to this polishing apparatus, for example, in a wiring formation process by a damascene method, a semiconductor wafer before embedding a conductor film in a wiring groove or a wiring hole, or a step such as a lower wiring layer is reflected, Examples thereof include a semiconductor wafer having irregularities on the surface of an interlayer insulating film. In these, the conductor film and the interlayer insulating film are the members to be polished.

  In FIG. 5, the polishing apparatus 4 includes a polishing chamber 5 and a wafer storage chamber 6. The polishing chamber 5 includes a polishing surface plate 8 to which a polishing cloth 7 is attached, a dresser 9, an inclination angle measuring means 10, and a dressing condition control unit 11. On the other hand, the wafer storage chamber 6 includes a wafer transfer means 12 and a wafer mounting table 21. However, the wafer transfer means 12 is assumed to be a means capable of transferring the wafer 17 between the polishing chamber 5 and the wafer storage chamber 6 as will be described later. In the present embodiment, instead of the wafer mounting table 21, for example, a cassette or the like that can store a wafer may be installed.

  The tilt angle measuring means 10 is a means capable of measuring the tilt angle of the surface of the polishing pad 7. For example, as shown in FIG. 5, a film thickness measuring unit 13 that measures the film thickness of the polishing pad 7 and an inclination angle calculating unit 14 that calculates an inclination angle from data obtained by the film thickness measuring unit 13 can do. Here, the film thickness measuring unit 13 can have a structure in which the eddy current sensor 15 is attached from the center of the polishing pad 7 toward the outer peripheral direction. Further, by connecting the rotating unit 16 to the film thickness measuring unit 13 and rotating the rotating unit 16 in the direction of the arrow, the film thickness measuring unit 13 may move on the polishing cloth 7 only at the time of measurement. it can. For example, a laser displacement meter may be attached to the film thickness measurement unit 13 instead of the eddy current sensor 15. A plurality of inclination angle measuring means 10 may be provided in the polishing chamber 5.

  The tilt angle measuring means 10 is connected to the dressing condition control unit 11. The dressing condition control unit 11 is a part that controls the dressing condition according to the obtained inclination angle, and more specifically, a part that creates control data related to the dressing condition from the measurement data obtained by the inclination angle measuring means 10. It is. The dressing condition control unit 11 is connected to the dresser 9 and dressing is performed according to the created control data.

  The wafer transfer means 11 is a means for transferring the wafer 17 between the polishing chamber 5 and the wafer storage chamber 6. For example, as illustrated in FIG. 5, the polishing chamber 5 includes a wafer holding unit 18 that holds the wafer 17 and a rotating unit 19 that is connected to the wafer holding unit 18, and the rotating unit 19 rotates in the direction of the arrow. It is possible to provide a mechanism in which the wafer holder 18 can move between the wafer storage chamber 6 and the wafer storage chamber 6. The wafer holding unit 18 is also rotatable, and both the polishing surface plate 8 and the wafer holding unit 18 are rotated during polishing.

  In FIG. 5, the rotating unit 20 is also connected to the dresser 9, and the dresser 9 is moved onto the polishing pad 7 by rotating the rotating unit 20 in the direction of the arrow during dressing. Further, the dresser 9 is also rotatable, and both the polishing surface plate 8 and the dresser 9 are rotated during dressing.

  In FIG. 5, a plurality of polishing chambers 5 can be provided. In that case, only one wafer storage chamber 6 may be provided, or a plurality of wafer storage chambers 6 may be provided according to the number of polishing chambers.

  FIG. 6 is a flowchart for explaining the polishing method in the present embodiment. Hereinafter, an example in which the polishing method of FIG. 6 is performed using the polishing apparatus of FIG. 5 will be described.

  First, the surface of the wafer 17 is polished while rotating the polishing cloth 7 and the wafer 17 in a state where the wafer 17 is pressed against the polishing cloth 7 attached to the polishing surface plate 8 (processing 101).

  Next, when polishing of a predetermined number of wafers is completed, the inclination angle of the surface of the polishing pad 7 is obtained by the inclination angle measuring means 10 (process 102). Here, the predetermined number of sheets can be set as appropriate according to circumstances. For example, the inclination angle may be measured every time one wafer is polished, or the inclination angle may be measured every time polishing of all the wafers stored in one cassette is completed.

  Specifically, the process 102 is performed as follows. First, the wafer 17 is transferred from the polishing chamber 5 to the wafer storage chamber 6 by the wafer transfer means 12. Next, the film thickness measuring unit 13 is moved to the upper surface of the polishing pad 7 to measure the film thickness at a predetermined location on the polishing pad 7. Thereafter, the tilt angle calculation unit 14 calculates the tilt angle from the film thickness data.

  The calculated inclination angle is transmitted to the dressing condition control unit 11 as measurement data. The dressing condition control unit 11 creates control data related to the dressing condition from the measurement data (process 103).

  Next, dressing of the polishing pad 7 is performed using the dresser 9 in accordance with the generated control data (processing 104).

  Specifically, the rotating unit 16 is rotated to retract the film thickness measuring unit 13 to a predetermined position in the polishing chamber 5, and then the rotating unit 20 is rotated so that the dresser 9 is placed on the upper surface of the polishing pad 7. Move and dress.

  After the dressing is completed, the rotating unit 20 is rotated again to retract the dresser 9 to a predetermined position in the polishing chamber 5, and then the wafer 17 is transferred from the wafer storage chamber 6 to the polishing chamber 5 by the wafer transfer means 12. Transport. Next, the wafer 17 is lowered onto the polishing cloth 7 to perform polishing (processing 105).

  The polishing process is terminated after the above processes 102 to 105 are repeated a predetermined number of times.

  Next, the process 103 in FIG. 6 will be described in more detail with reference to FIG.

  First, it is determined from the measurement data transmitted from the tilt angle measuring means 10 whether or not the tilt angle is within an allowable range (processing 103a). Here, the allowable range of the tilt angle can be set as appropriate. For example, the range of the tilt angle where the in-plane variation of the polishing rate is 15% or less can be set as the allowable range in the relationship of FIG.

  If the inclination angle exceeds the allowable range, the dressing conditions are changed and new control data is created (process 103b). Here, as the dressing conditions, for example, the rotational speed D (rpm) of the dresser or the rotational speed P (rpm) of the polishing surface plate can be cited.

  For example, when the inclination angle is too large on the plus side, the rotational speed P of the polishing surface plate is increased without changing the rotational speed D of the dresser. In this case, the rotational speed D of the dresser may be reduced without changing the rotational speed P of the polishing surface plate. On the other hand, when the inclination angle is too large on the minus side, the rotational speed P of the polishing surface plate is decreased without changing the rotational speed D of the dresser. In this case, the rotational speed D of the dresser may be increased without changing the rotational speed P of the polishing surface plate.

  On the other hand, when the inclination angle is within the allowable range, it is not necessary to change the dressing conditions. That is, control data is created with the predetermined number of rotations of the dresser and the number of rotations of the polishing surface plate (process 103c).

  In the above embodiment, the case where the polishing process and the dressing process are performed separately has been described, but the present invention is not limited to this. In the present invention, the polishing step and the dressing step may be performed simultaneously. For example, in the polishing apparatus shown in FIG. 5, dressing may be performed at an empty portion of the polishing pad 7 while the wafer 17 is being polished. In this case, dressing conditions can be optimized in real time for each wafer by performing dressing and polishing in a state where the film thickness measuring unit 13 is installed on the upper surface of the polishing pad 7.

  As described above, according to the polishing apparatus and the polishing method of the present invention, since the dressing conditions can be optimized by obtaining the inclination angle on the surface of the polishing pad, the in-plane film thickness uniformity of the polishing pad can be improved. This makes it possible to reduce the in-plane variation of the polishing rate with respect to the surface to be polished. Therefore, by manufacturing the semiconductor device using the polishing method according to the present invention, the surface of the semiconductor wafer can be flattened with high accuracy, so that a semiconductor device having excellent electrical characteristics and reliability can be manufactured. it can. In addition, the yield in the manufacturing process of the semiconductor device can be improved.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

It is explanatory drawing of dressing. It is a figure which shows the relationship between the inclination | tilt angle of polishing cloth, and the in-plane dispersion | variation in polishing rate. It is sectional drawing of the polishing cloth from which an inclination angle differs, (a) is a case where an inclination angle is large on the plus side, (b) is a case where an inclination angle is large on the minus side. It is a figure which shows the dispersion | variation in the grinding | polishing speed in the surface of a semiconductor wafer. It is a top view of the polish device in this embodiment. It is a flowchart explaining the grinding | polishing method in this Embodiment. It is a flowchart explaining the process 103 of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,8 Polishing surface plate 2,7 Polishing cloth 3,9 Dresser 4 Polishing apparatus 5 Polishing chamber 6 Wafer storage chamber 10 Inclination angle measurement means 11 Dressing condition control part 12 Wafer conveyance means 13 Film thickness measurement part 14 Inclination angle calculation part 15 Eddy current sensor 16, 19, 20 Rotating unit 17 Wafer 18 Wafer holding unit 21 Wafer mounting table

Claims (8)

A polishing surface plate;
A polishing cloth attached to the polishing surface plate to polish the member to be polished;
A dresser for dressing the surface of the polishing cloth;
A polishing apparatus comprising: an inclination angle measuring means for measuring an inclination angle of the surface of the polishing cloth. The tilt angle measuring means includes a film thickness measuring unit that measures the film thickness of the polishing cloth,
The polishing apparatus according to claim 1, further comprising an inclination angle calculation unit that calculates an inclination angle from the film thickness.   The polishing apparatus according to claim 1, wherein the film thickness measurement unit includes an eddy current sensor.   The polishing apparatus according to claim 1, wherein the film thickness measuring unit includes a laser displacement meter.   The polishing apparatus according to claim 1, further comprising a dressing condition control unit that controls the dressing condition according to the inclination angle. Polishing the surface of the wafer while rotating the polishing surface plate and the wafer while pressing the wafer against a polishing cloth attached to the polishing surface plate;
Obtaining a tilt angle of the surface of the polishing cloth;
Creating control data relating to dressing conditions from the tilt angle;
A polishing method comprising: dressing the polishing cloth while rotating the polishing platen and a dresser according to the control data.   The polishing method according to claim 6, wherein the dressing condition is a rotation speed of the polishing surface plate or a rotation speed of the dresser. Forming a film to be processed on a semiconductor wafer;
A method for manufacturing a semiconductor device, comprising: polishing the film to be processed by the polishing method according to claim 6.

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