JP2008264944A - Polishing device, semiconductor device manufacturing method using this, and semiconductor device manufactured by this method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polishing device improved in through-put. <P>SOLUTION: This polishing device 1 is configured to set a gain value and a dress time of a polishing pad 13 in a dress position control of a dresser 30 according to a dress rate by a polishing control section 60 in an adjust process before start of a series of polishing processes for polishing a plurality of semiconductor wafers W successively by a polishing tool 10. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a polishing apparatus for polishing the surface of an object to be polished. The present invention also relates to a semiconductor device manufacturing method using this polishing apparatus and a semiconductor device manufactured by this method.

  A polishing apparatus for performing surface polishing of a polishing object (for example, a semiconductor wafer) includes a polishing tool to which a polishing pad is attached and a polishing object holding means such as a turntable for holding the polishing object. The polishing tool and the polishing object holding means are moved relative to each other while the polishing pad is in contact with the polishing object held by the object holding means, and the surface of the polishing object is polished. The surface of the polishing pad in such a polishing apparatus is clogged with scraps of the polishing object generated by polishing as the surface polishing progresses or a residue of slurry supplied to the surface to be polished of the polishing object. Therefore, it is necessary to dress with a dresser provided separately.

  The polishing state of the polishing object varies depending on the shape of the polishing pad provided in the polishing tool. In other words, it is possible to adjust the polishing state of the object to be polished by adjusting the shape of the polishing pad to a predetermined shape. Therefore, it is necessary to dress the polishing pad not only to eliminate clogging of the pad surface but also to make the shape of the polishing pad to the predetermined shape. Changing the relative position of the dresser with respect to the polishing pad changes how the polishing pad is scraped, so the polishing pad is dressed while measuring the change in the surface shape of the polishing pad so that the shape of the polishing pad is gradually determined. The shape can be approached.

Conventionally, an operation of finishing a polishing pad into a predetermined shape has been performed manually, so to speak, by an operator through trial and error. Therefore, in the polishing pad shape creation process (hereinafter referred to as the adjustment process), which is the previous stage of the polishing process (a series of processes for continuously polishing a plurality of objects to be polished with a polishing tool), the shape adjustment of the polishing pad It takes a long time to reduce the throughput of the entire polishing process. Therefore, a polishing apparatus that automatically performs an operation of finishing a polishing pad into a predetermined shape has been proposed (see, for example, Patent Document 1).
WO 06/106790 pamphlet

  However, in such a conventional polishing apparatus, when the polishing pad cutting speed (dress rate) by the dresser increases, the polishing pad scraping amount (break-in amount) in the adjustment process tends to be larger than the setting. . As a result, since the number of times that the polishing pad can be dressed in the polishing process is reduced, the amount of the polishing object that can be polished with one polishing pad is reduced, and the number of replacements of the polishing pad is increased. In some cases, the throughput of the system was reduced.

  The present invention has been made in view of such problems, and a polishing apparatus capable of improving the throughput of the entire polishing process, a semiconductor device manufacturing method using the polishing apparatus, and a semiconductor manufactured by the method The purpose is to provide a device.

  In order to achieve such an object, a polishing apparatus according to the present invention includes a polishing tool to which a polishing pad is attached and a polishing object holding means for holding a polishing object, and is held by the polishing object holding means. In the polishing apparatus for polishing the surface of the polishing object by relatively moving the polishing tool and the polishing object holding means while the polishing pad is in contact with the polishing object, the polishing tool A dresser for dressing the polishing pad by bringing a rotated dress surface into contact with the surface of the polishing pad in an attached state, and a pad shape measurement for measuring the shape of the polishing pad attached to the polishing tool Means.

  Furthermore, in an adjusting process before starting a series of polishing processes for continuously polishing a plurality of objects to be polished by the polishing tool, the dressing of the polishing pad by the dresser and the polishing pad by the pad shape measuring means are performed. By alternately performing shape measurement, data indicating the relationship between the dress position represented by the distance between the rotation axis of the polishing pad and the rotation axis of the dresser and the shape change of the polishing pad is obtained. However, it has a pad processing control means for processing the polishing pad into a predetermined target shape while controlling the dress position, and in the adjustment step, the gain value in the control of the dress position is determined by the pad shape measuring means. Gain setting to be set according to the dress rate calculated when shape measurement is performed Means, in said adjusting step, a dress time setting means for setting in accordance with the polishing pad dress time by the dresser in the dress rate is provided.

  In the above polishing apparatus, in the adjusting step, the dress where the change rate of the uneven displacement of the polishing pad is substantially zero based on the data indicating the relationship between the dress position and the shape change of the polishing pad. A temporary position keeping position that is a position, and a dress position setting means for setting a dress position that minimizes a change in the shape of the polishing pad based on the temporary shape keep position. The shape keep position is preferably an average value of the temporary shape keep positions calculated every time the shape measurement is performed by the pad shape measuring means.

  Further, in the above polishing apparatus, in the adjusting step, a condition that the shape of the polishing pad measured by the pad shape measuring means is substantially the same as the target shape is continuously satisfied a predetermined number of times, and When the condition that the number of effective data among the data acquired by the pad machining control means is equal to or greater than a predetermined number and the condition that the amount of polishing of the polishing pad exceeds a predetermined amount is satisfied, the adjustment It is preferable to include an adjusting process ending means for ending the process.

  Moreover, the semiconductor device manufacturing method according to the present invention is characterized in that the object to be polished is a semiconductor wafer and includes a step of planarizing the surface of the semiconductor wafer using the polishing apparatus according to the present invention.

  The semiconductor device according to the present invention is manufactured by the semiconductor device manufacturing method according to the present invention.

  According to the present invention, the throughput of the entire polishing process can be improved.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a polishing apparatus 1 according to an embodiment of the present invention. The polishing apparatus 1 includes a polishing tool 10 for polishing an object to be polished, a dresser 30 for dressing a polishing pad 13 attached to the polishing tool 10, a turntable 40 for holding the object to be polished, and a pad for measuring the shape of the polishing pad 13. In addition to the shape measuring instrument 20 and the process working unit 70 for carrying out process work such as conveyance of the object to be polished and the polishing pad 13, control units (polishing control unit 60, measurement control unit 61 and monitoring control unit 62) for controlling these operations. ).

  Further, the polishing apparatus 1 is provided with three work stations including a pad shape measuring station ST1, a dress station ST2, and a polishing station ST3, and the polishing tool 10 moves between these three stations ST1, ST2, ST3. Can be done. In the following description, it is assumed that the object to be polished is a semiconductor wafer, and the polishing apparatus 1 is a CMP apparatus that performs chemical mechanical polishing on the surface of the semiconductor wafer.

  The polishing tool 10 comprises a rotary shaft 11 extending in the vertical direction and a tool body 12 attached to the lower end portion of the rotary shaft 11, and the polishing pad 13 is attached to a plate 14 with a double-sided tape or the like. 14 and the polishing pad 13 are operated integrally. The plate 14 is vacuum-sucked to the tool body 12, and the polishing pad 13 is attached together with the plate 14 in a replaceable manner. The polishing pad 13 is made of foaming polyurethane or the like, and the shape thereof is not only a simple disk shape but also a thin donut shape having a hole in the center. In this embodiment, it is assumed that the polishing pad 13 is a thin donut shape (see FIG. 2). The rotation control of the rotating shaft 11 of the polishing tool 10 is performed by a motor (not shown), and the drive control of the motor is performed by the polishing control unit 60.

  The pad shape measuring station ST1 is a work station for measuring the shape of the polishing pad 13, and the pad shape measuring instrument 20 can be positioned below the polishing tool 10 moved to the pad shape measuring station ST1. The pad shape measuring instrument 20 includes a sensor holding unit 21 and a sensor 22 held by the sensor holding unit 21, and the sensor 22 is movable with respect to the sensor holding unit 21 in a horizontal plane. The sensor 22 is composed of an optical (that is, non-contact type) displacement sensor composed of a light emitting element and a light receiving element. Thus, the distance between the pad shape measuring instrument 20 and the measurement position on the polishing pad 13 can be measured. Therefore, according to the pad shape measuring instrument 20, it is possible to calculate the relative height between different measurement positions on the polishing pad 13.

  In this embodiment, the sensor 22 is an optical displacement sensor, but this is only an example, and an ultrasonic displacement sensor or the like may be used as long as it is a non-contact type. For example, a probe may be used. Control of relative movement of the sensor 22 with respect to the sensor holding unit 21 is performed by a motor (not shown), and driving control of the motor is performed by a measurement control unit 61 connected to the polishing control unit 60. Further, the shape measurement data of the polishing pad 13 obtained by the sensor 22 is transmitted from the measurement control unit 61 to the polishing control unit 60.

  The dressing station ST2 is a work station for dressing the polishing pad 13, and the dresser 30 can be positioned below the polishing tool 10 moved to the dressing station ST2. The dresser 30 includes a rotary shaft 31 extending in the vertical direction (that is, parallel to the rotary shaft 11 of the polishing tool 10), and a disk-shaped dress plate 33 attached to the upper portion of the rotary shaft 31 via a gimbal mechanism 32. Thus, the upper surface of the dress plate 33 is a dress surface. The rotation control of the rotary shaft 31 of the dresser 30 is performed by a motor (not shown), and the drive control of this motor is performed by the polishing control unit 60. The dresser 30 dresses the surface of the polishing pad 13 by polishing the surface of the polishing pad 13 attached to the polishing tool 10, and polishes a plurality of semiconductor wafers W at the following polishing station ST3. Each time the polishing tool 10 is moved to the dressing station ST2, the upper surface (dressing surface) of the rotated dress plate 33 is brought into contact with (pressed against) the polishing pad 13 of the rotated polishing tool 10. And dressing the polishing pad 13.

  In addition, the dress of the polishing pad 13 is intended not only for the purpose of sharpening the polishing pad 13 as described above, but also for processing the shape of the polishing pad 13 into a predetermined shape. In addition to the previous stage of starting a series of polishing processes for continuously polishing W, this process is also performed a plurality of times in the intermediate process of this polishing process. Here, the distance between the rotating shaft 11 of the polishing tool 10 and the rotating shaft 31 of the dresser 30 can be accurately controlled by the polishing controller 60, and, as will be described later, according to the distance. The polishing pad 13 can be finished in a desired shape. Hereinafter, the distance between the rotating shaft 11 of the polishing tool 10 and the rotating shaft 31 of the dresser 30 will be referred to as a dress position P (see FIG. 2).

  The polishing station ST3 is a work station for polishing the surface of the semiconductor wafer W by using the polishing tool 10, and the rotary table 40 can be positioned below the polishing tool 10 moved to the polishing station ST3. The rotary table 40 includes a rotary shaft 41 extending in the vertical direction (that is, parallel to the rotary shaft 11 of the polishing tool 10) and a rotary plate 42 fixed to the upper portion of the rotary shaft 41, and rotates the rotary shaft 41. Thus, the rotating plate 42 can be rotated in the horizontal plane. A vacuum suction chuck mechanism (not shown) is provided on the upper surface of the rotating plate 42, and the semiconductor wafer W can be sucked and held on the rotating plate 42 by this vacuum chuck mechanism. Both the rotation control of the rotating shaft 41 and the horizontal swing control of the rotating shaft are performed by a motor (not shown), and drive control of these motors is performed by the polishing control unit 60. Then, both the rotary table 40 and the polishing tool 10 are rotated while the polishing pad 13 is in contact with the surface of the semiconductor wafer W from above, and the polishing tool 10 is swung horizontally with respect to the rotary table 40. By polishing, the entire surface of the semiconductor wafer W is polished.

  The process work unit 70 includes a robot arm that transports the semiconductor wafer W and the polishing pad 13 that are objects to be polished, a slurry supply device (not shown) that supplies slurry to the surface to be polished of the semiconductor wafer W, and the like. Composed. Further, the monitoring control unit 62 monitors the progress of a polishing process (described later) of the semiconductor wafer W performed by the polishing control unit 60, for example, and controls the operation of the process work unit 70 according to the progress of the polishing process. .

  The polishing process of the semiconductor wafer W in the polishing apparatus 1 includes (1) attachment of the polishing pad 13 to the polishing tool 10 by the process working unit 70 → (2) processing (dressing) of the polishing pad 13 by the dresser 30 → (3) Loading of the semiconductor wafer W by the process working unit 70 and attachment to the turntable 40 → (4) Dressing of the polishing pad 13 by the dresser 30 → (5) Polishing of the semiconductor wafer W by the polishing pad 13 → (6) Process working unit 70 The removal and unloading of the semiconductor wafer W from the turntable 40 by (3) → (4) → (5) → (6) → (3) →... In the polishing apparatus 1, as described above, an adjustment for processing the polishing pad 13 provided in the polishing tool 10 before starting a series of polishing steps for continuously polishing a plurality of semiconductor wafers W with the polishing tool 10. Although there is a step (step corresponding to the above (2)), in the polishing apparatus 1, the processing step of the polishing pad 13 is automatically performed, and the details of the adjustment step will be described below.

  First, the shapes that the polishing pad 13 can take will be described. The shape of the polishing pad 13 has a great influence on the polishing state of the semiconductor wafer W, which is an object to be polished. The specific shape of the polishing pad 13 is a convex cone shape in which the central portion projects downward from the peripheral portion (FIG. 2). (See (A)), 3 in which the entire surface is flat (flat) (see FIG. 2 (B)), and a concave cone shape (see FIG. 2 (C)) whose central portion is recessed above the peripheral portion. It becomes a kind.

  The shape of the polishing pad 13 is not uniquely determined by the distance between the rotating shaft 11 of the polishing tool 10 and the rotating shaft 31 of the dresser 30, that is, the dress position P. Only when the polishing pad 13 is dressed (polished) with the dress position P being a predetermined value Pv as shown in FIG. 2B, the shape of the polishing pad 13 does not change. . Here, if the dress position P that minimizes the shape change of the polishing pad 13 is referred to as “shape keep position Pv”, in the state where the dress position P is larger than the shape keep position Pv (P> Pv), FIG. In the state where the convex shape increases as shown in (A) and the dress position P is smaller than the shape keep position Pv (P <Pv), the concave shape increases as shown in FIG. That is, the change rate of the uneven shape of the polishing pad 13 is 0 at the shape keep position Pv, the convex shape (+) is advanced when P> Pv, and the concave shape (−) is advanced when P <Pv. The shape keep position Pv can take different values depending on the hardness and shape of the polishing pad 13, the shape of the dresser 30 (dress plate 33), the roughness of the eyes (count), and the like.

  Further, the dress position P can be expressed by the following equation (A1) using the deviation ε from the shape keep position Pv. Therefore, the shape of the polishing pad 13 is maintained as it is when ε = 0, can be expressed as a conical shape progressing in a convex shape when ε> 0, and a conical shape progressing in a concave shape when ε <0. (See FIG. 2).

  P = Pv + ε (A1)

  Here, the shape of the polishing pad 13 desired by the operator is referred to as a “target shape”. The target shape indicates a predetermined surface irregularity state, a predetermined break-in amount, or a predetermined range of groove depth. In order to realize this target shape, it is necessary to specify the value of the uneven displacement δ, the pad thickness th, and the groove depth de as shown in FIG. The uneven displacement δ is a value obtained by multiplying the complementary angle θ of the apex angle of the cone obtained by approximating the surface of the polishing pad 13 in a conical shape by the difference length L between the outer radius and the inner radius of the polishing pad 13. Since the complementary angle θ is very small, the above calculation can be performed simply by multiplication without using a trigonometric function. Therefore, the target shape is the same as that for determining the target value of the concave / convex displacement δ, and the value of the concave / convex displacement δ determined corresponding to the target shape is hereinafter referred to as “target concave / convex displacement δT”.

  Since the difference in the unevenness of the target shape can be determined by the polarity of the target unevenness displacement δT, the desired target shape can be defined only by the target unevenness displacement δT including the sign. Specifically, the convex cone shape is defined as the target shape when δT> 0, the flat shape is defined as the target shape when δT = 0, and the concave cone shape is defined as the target shape when δT <0. The pad thickness th is the distance from the average surface position of the polishing pad 13 to the attachment surface of the polishing pad 13 of the plate 14. The groove depth de is an average depth of each groove.

  In order to obtain a certain target uneven displacement δT, it is necessary to determine the uneven amount of the difference from the current uneven displacement δ. Since the relationship between the displacement amount ε and the variation amount of the uneven displacement δ per unit time with respect to the previous shape keep position Pv has a substantially linear relationship, the product of the displacement amount ε and the dressing time is processed by the unevenness. It corresponds to the amount. The polishing pad 13 can be set to the target shape by controlling the deviation amount ε and the dressing time well. However, the shape keep position Pv needs to be known in order to determine the shift amount ε.

  As a means for realizing this, the dress shape keep position Pv is obtained by alternately repeating the dressing of the polishing pad 13 by the dresser 30 and the measurement of the shape of the polishing pad 13 by the pad shape measuring device 20 to change the shape of the dress position P and the polishing pad 13. It is possible to process the target uneven displacement δT while estimating and controlling the dress shape keep position Pv while collecting data indicating the relationship with the (uneven displacement change amount). At the same time, the dress position at the time of polishing the next semiconductor wafer W is set to the previous shape keep position Pv, and the target uneven displacement δT can be always maintained.

  Various methods for estimating the shape keep position Pv are conceivable. In this embodiment, the shape keep position Pv is estimated from the difference between the shape measurement value of the polishing pad 13 by the current pad shape measuring instrument 20 and the previous shape measurement value. The method used was used. Details are given below.

  As described above, the target shape of the polishing pad 13 is one of the convex cone shape shown in FIG. 2A, the flat shape shown in FIG. 2B, and the concave cone shape shown in FIG. When dressing of the polishing pad 13 is performed by setting the dress position P of the dresser 30 to a position (Pv + εc) obtained by adding a certain shift amount εc to the shape keeping position Pv, the shape of the polishing pad 13 after dressing is εc = 0. Is the same as the shape before processing, when εc> 0, it becomes a convex conical shape than the shape before processing, and when εc <0, it becomes a concave conical shape than the shape before processing.

  From the above, if the shape keep position Pv of the dresser 30 is clear, the dresser 30 is shifted by the amount εc based on the shape keep position Pv, and the dressing is performed for a predetermined dressing time. However, since the value of the shape keep position Pv is actually unknown, it is necessary to first know the approximate position of the shape keep position Pv. For this, first, the dresser 30 is set at a dress position P (actually P = Pv + ε) estimated as the shape keep position Pv, and then dressed for a predetermined dressing time Td. The change rate dδ / dt (= Vδ) of the displacement δ is calculated by the following equation (A2).

  Vδ = dδ / dt = Eδ / Td (A2)

  However, Eδ is a difference in uneven displacement before and after the dress. Here, the dressing of the polishing pad 13 by the dresser 30 and the measurement of the uneven displacement δ of the polishing pad 13 before and after the dress are performed by the polishing control unit 60 and the measurement control unit 61 for controlling the movement and rotation of the polishing tool 10, This is done automatically by controlling the rotation of the sensor and controlling the operation of the pad shape measuring instrument 20.

  Here, it is known that the change speed Vδ of the uneven displacement δ calculated by the equation (A2) is proportional to the deviation ε from the shape keep position Pv, and therefore the proportional constant is 1 / Kv. Then, Vδ can be expressed by the following equation (A2) using Kv and ε.

  Vδ = (1 / Kv) × ε (A3)

  Here, the coefficient Kv is a value set (assumed) empirically, and the change speed Vδ of the unevenness displacement of the polishing pad 13 is a value obtained (measured) based on the shape measurement of the polishing pad 13. Therefore, the value of the deviation ε from the shape keep position Pv can be calculated from these two values and the following equation (A3) ′ obtained by modifying the equation (A3).

  ε = Kv × Vδ (A3) ′

As described above, since the displacement amount ε can be calculated from the equation (A3) ′, the shape keep position Pv can be obtained from the following equation (A1) ′ obtained by modifying the equation (A1).
Pv = P−Kv × Vδ (A1) ′

  Here, the coefficient Kv is referred to as a speed gain. If the set (assumed) speed gain Kv has no variation (in other words, an accurate value), the coefficient Kv is obtained from the above equation (A1) ′. Although the shape keep position Pv is accurate, in practice, the speed gain Kv generally varies, and thus the shape keep position Pv obtained here is not necessarily accurate. Accordingly, the shape keep position Pv obtained by calculation here is assumed to be only temporary, and will be referred to as “temporary shape keep position Pf” hereinafter. In the present embodiment, the speed gain Kv is set according to the dress rate.

  When the provisional shape keep position Pf is obtained as described above, a shift amount εc (described above) for obtaining the target uneven displacement δT by dressing with the dressing time Td is obtained based on the shape measurement of the polishing pad 13, The dress position Pc for shape control (hereinafter referred to as “control dress position”) is calculated by the equation (A4) obtained by setting P = Pc, Pv = Pf, and ε = εc in the above equation (A1). .

  Pc = Pf + εc (A4)

  Here, at the control dress position Pc (= Pf + εc) obtained by adding the shift amount εc to the temporary shape keep position Pf, the uneven displacement δ of the polishing pad 13 can be set to the target uneven displacement δT by dressing for the dressing time Td. Assuming that the change speed Vδ of the uneven displacement δ due to the dress is (δT−δ) / Td, the following equation (A5) can be obtained from the above equation (A3) ′.

  εc = Kv × {(δT−δ) / Td} (A5)

  Here, assuming that Kv / Td = Kp, the following equation (A6) can be obtained from the equations (A4) and (A5).

  Pc = Pf−Kp × (δ−δT) (A6)

  The coefficient Kp is referred to as a position gain, and the control dress position Pc is controlled by feedback control corresponding to the uneven displacement δ measured by the pad shape measuring instrument 20. In the present embodiment, the position gain Kp is set in accordance with the dress rate, similarly to the speed gain Kv.

  Next, details of the adjustment process will be described with reference to the flowchart shown in FIG. Here, the distance between the rotating shaft 11 of the polishing pad 13 and the rotating shaft 31 of the dresser 30, that is, the dress position P is represented by P (n-1), and the dressing time at that time is represented by t (n-1). To express. Note that the subscript n of P (n-1) and t (n-1) means the number of data obtained in the first process (shape measurement of the polishing pad 13) described later.

  In the adjustment process, first, in step S1, an initial dress position P (0) and an initial dress time t (0) are set. At this time, the number of data described above is set to n = 0, and the good profile number g at which the measured uneven displacement δ is substantially the same as the target uneven displacement δT is set to g = 0. Note that the initial dress position P (0) is an average shape keep position obtained empirically or a shape keep position that has already been obtained and stored. The initial dressing time t (0) is, for example, an empirically obtained dressing time.

  Next, in step S <b> 2, a first process is performed in which the polishing controller 60 performs dressing and shape measurement of the polishing pad 13. In the first process, as shown in FIG. 4, first, in step S21, the dress position P (n-1) and the dress time t (n-1) set in step S1 or step S6 are input.

  Next, in step S <b> 22, it is determined whether or not the dress position P (n−1) is within the movable range of the polishing tool 10. When the determination is Yes, the process proceeds to step S23, the polishing tool 10 is moved to the dressing station ST2, and the polishing pad 13 according to the dress position P (n-1) and the dressing time t (n-1) input in step S21. Do the dress. On the other hand, when the determination is No, it is determined that a position error has occurred, and the adjustment process is terminated.

  When step S23 ends, the process proceeds to step S24, where it is determined whether or not the dressing of the polishing pad 13 has ended normally. If the determination is Yes, the polishing tool 10 is moved to the pad shape measuring station ST1, and the pad shape measuring instrument 20 measures the uneven displacement δ, the thickness th, and the groove depth de of the polishing pad 13 (step S25). ). In addition, the watering process which pours water on the lower surface of the polishing pad 13 is performed after the measurement. On the other hand, if the determination is No, it is determined that the dress has failed and the adjustment process is terminated.

  Here, as shown in FIG. 2, the uneven displacement δ is the difference length between the outer radius and the inner radius of the polishing pad 13 with respect to the complementary angle θ of the apex angle of the cone obtained by approximating the surface of the polishing pad 13 in a conical shape. It is a value multiplied by L. As shown in FIG. 2, the pad thickness th is the distance from the average surface position of the polishing pad 13 to the attachment surface of the polishing pad 13 of the polishing tool 10. Further, the groove depth de of the polishing pad 13 is defined here as an average value of all the depths d of the grooves of the polishing pad 13 (see FIG. 2). When the number of data is n, the irregularity displacement of the polishing pad 13 measured after completion of dressing is δ (n−1), the thickness of the polishing pad 13 is th (n−1), and the groove of the polishing pad 13 is Depth is de (n-1).

  When step S25 ends, the process proceeds to step S26, and it is determined whether or not the effective number of measurements in the measurement of step S25 is greater than or equal to a threshold value. If the determination is Yes, the process proceeds to step S27, and if the determination is No, the adjustment process is terminated as a measurement failure.

  In step S27, it is determined whether or not there is an abnormality in the groove depth de of the polishing pad 13 measured in step S25. If there is no abnormality in the groove depth de and the determination is Yes, the process proceeds to step S28, the profile of the uneven displacement δ (n-1) measured in step S25, the thickness th (n-1) of the polishing pad 13, and The dressing time t (n-1) at that time is recorded in a data table (not shown). On the other hand, when there is an abnormality in the groove depth de and the determination is No, the adjustment process is terminated as a groove error.

  When step S28 ends, the process proceeds to step S29, where the uneven displacement δ (n-1), thickness th (n-1), and groove depth de (n-1) of the polishing pad 13 measured in step S25 are obtained. Output, and proceed to step S3.

  When the first process is completed in this way, in the next step S3, it is determined whether or not the scraping amount of the polishing pad 13 is larger than a predetermined scraping amount BA. Here, the amount of polishing of the polishing pad 13 represents the amount of break-in of the polishing pad 13. That is, the scraping amount B (n-1) when the number of data is n is the thickness th (n-1) of the polishing pad 13 when the number of data is n and the thickness of the polishing pad 13 at the first measurement. Taking the difference from th (0), it is expressed by the following equation (1).

  B (n-1) = th (n-1) -th (0) (1)

  When the determination is Yes, the process proceeds to step S4, and the polishing control unit 60 performs a second process in which the speed gain and the position gain are calculated. On the other hand, when determination is No, step S4 is skipped and it progresses to step S5. In the second process of step S4, as shown in FIG. 5, first, in step S41, the thickness th (n-1) and the dressing time t (n-1) of the polishing pad 13 obtained in each step are input. I do.

  Next, in step S42, the dress rate, which is the cutting speed of the polishing pad 13, is calculated based on the thickness th (n-1) and the dressing time t (n-1) of the polishing pad 13 input in step S41. . The dress rate is the rate of change of the thickness th of the polishing pad 13, and when the integrated dressing time is Σt (n-1), the dress rate Rd (n-1) when the number of data is n is the number of data. From the difference between the thickness th (n-1) of the polishing pad 13 at n and the thickness th (0) of the polishing pad 13 at the first measurement, it is expressed by the following equation (2).

  Rd (n-1) = {th (n-1) -th (0)} / Σt (n-1) (2)

  Next, in step S43, when the predetermined minimum dress rate is Rmin and the predetermined maximum dress rate is Rmax, the dress rate Rd (n-1) calculated in step S42 is expressed by the following equation (3). It is determined whether or not the condition is satisfied.

  Rmin ≦ Rd (n−1) ≦ Rmax (3)

  When the determination is Yes, the process proceeds to step S44, and the speed gain and the position gain are calculated according to the dress rate Rd (n-1) calculated in step S42. On the other hand, if the determination is No, it is determined that there is a dress rate error, and the adjustment process is terminated. The speed gain Kv and the position gain Kp are expressed by the following equation (4), for example, where KA is a predetermined coefficient.

  Kv = Kp = KA × Rd (n−1) (4)

  When step S44 ends, the process proceeds to step S45, where the speed gain Kv, the position gain Kp, and the dress rate Rd (n-1) at that time calculated in step S44 are output, and the process proceeds to step S5.

  When the second process ends in this way, it is determined in the next step S5 whether n ≧ 2. When the determination is Yes, the process proceeds to step S6, and the polishing control unit 60 performs a third process in which the next dress position and dress time are calculated. On the other hand, when determination is No, step S6 is skipped and it progresses to step S7. In the third process of step S6, as shown in FIG. 6, first, in step S61, the profile of the uneven displacement δ (n−1) set in each step, the speed gain Kv, the position gain Kp, and the dress rate Rd (n -1), and the dress position P (n-1) and dress time t (n-1) at that time are input.

  Next, in step S62, based on the profile of the concavo-convex displacement δ (n-1) input in step S61 and the dressing time t (n-1), the amount of change in the concavo-convex displacement δ (n-1) per unit time. Δ (that is, the change speed Vδ of the uneven displacement δ described above) is calculated, and the temporary shape keep position Pf is calculated from the calculated Δ. The variation Δ of the uneven displacement δ (n-1) per unit time is obtained from the difference between the uneven displacement δ (n-1) at the n-th measurement and the uneven displacement δ (n-2) of the previous time, It is expressed by the following equation (5). The temporary shape keep position Pf is expressed by the following equation (6) from the above-described equation (A1) ′, where P = P (n−1) and Vδ = Δ.

Δ = {δ (n−1) −δ (n−2)} / t (n−1) (5)
Pf = P (n−1) −Kv × Δ (6)

  Next, in step S63, the provisional shape keep position Pf calculated in step S62 so far is averaged.

  Next, in step S64, when the predetermined minimum dress position is Pmin and the predetermined maximum dress position is Pmax, the temporary shape keep position Pf averaged in step S63 is expressed by the following equation (7): It is determined whether or not the above is satisfied.

  Pmin ≦ Pf ≦ Pmax (7)

  When the determination is Yes, the process proceeds to step S65, and the next dress position is calculated based on the temporary shape keep position Pf averaged in step S63. On the other hand, if the determination is No, it is determined that there is a position error, and the adjustment process is terminated. The next dress position nP is expressed by the following equation (8) from the above equation (A6), assuming that Pc = nP and δ = δ (n−1).

  nP = Pf−Kp × {δ (n−1) −δT} (8)

  When step S65 ends, the process proceeds to step S66, and the next dressing time is calculated according to the dress rate Rd (n-1) input in step S61. The next dressing time nt is expressed by, for example, the following equation (9), where KB is a predetermined coefficient.

  nt = KB / Rd (n-1) (9)

  When step S66 ends, the process proceeds to step S67, and the next dress position nP and the next dress time nt calculated in steps S65 and S66 are used as the dress position P (n-1) and dress time t (n -1) and proceeds to step S7.

  When the third process is completed in this way, in the next step S7, the number of data obtained in the first process (measurement of the shape of the polishing pad 13) is set to n = n + 1, and the process proceeds to step S8.

  Next, in step S8, it is determined whether or not the uneven displacement δ (n−1) whose shape has been measured in the first process (step S2) is substantially the same as the target uneven displacement δT (within a predetermined tolerance). If the determination is Yes, the process proceeds to step S9, the good profile number is set to g = g + 1, and the process proceeds to step S10. On the other hand, when determination is No, it progresses to step S13.

  In step S10, it is determined whether or not the number of good profiles g is a predetermined profile number G or more. If the determination is Yes, the process proceeds to step S11. If the determination is No, the process proceeds to step S13.

  In step S11, it is determined whether or not the amount of polishing of the polishing pad 13 is larger than a predetermined target amount of cutting BT. Whether or not the polishing amount of the polishing pad 13 is larger than the target cutting amount BT is determined in order to obtain a familiarity between the polishing pad 13 and the semiconductor wafer W when polishing with the polishing pad 13. This is because 13 surface layers must be cut off. If the determination is Yes, the process proceeds to step S12, the result of the adjustment process is displayed, and the adjustment process is terminated as normal completion. On the other hand, when determination is No, it progresses to step S13.

  In step S13, it is determined whether or not the data number n is equal to or greater than a predetermined limit data number N. If the determination is No, the process returns to Step S2 and the processing from Step S2 is performed again. If the determination is Yes, the adjustment process is terminated because there is an error.

  As a result, the adjustment process is completed, but the polishing apparatus 1 of the present embodiment is configured to send information such as whether the adjustment process has been completed, that is, whether the process has been completed normally or ended in an error, to the monitoring control unit 62. Yes. When the monitoring control unit 62 receives information indicating that the dressing condition setting sequence has been normally completed, the monitoring control unit 62 performs normal operation of the process work unit 70. Then, take appropriate action according to the error contents. For example, when information indicating that the adjustment process has ended in error is received, the processing process of the polishing pad 13, and hence the polishing process of the semiconductor wafer W, is delayed. Therefore, it is necessary to prevent a new semiconductor wafer W from being introduced into the apparatus.

  As the polishing apparatus 1 undergoes the above-described steps, the polishing pad 13 is processed into the target uneven displacement δT, and the target uneven displacement δT can be maintained. Thereby, the preparation for the polishing process of the semiconductor wafer W is completed.

  When the preparation of the polishing process is completed, the process working unit 70 is operated to put the semiconductor wafer W into the polishing station ST3 of the polishing apparatus 1 and hold it on the upper surface of the rotating plate 42. When the polishing tool 10 is moved to the polishing station ST3 and positioned above the semiconductor wafer W, both the polishing tool 10 and the turntable 40 are rotated. When both the polishing tool 10 and the turntable 40 start to rotate, the polishing tool 10 is lowered and the polishing pad 13 is brought into contact with the semiconductor wafer W. Thereby, relative movement occurs between the semiconductor wafer W and the polishing pad 13, and the surface of the semiconductor wafer W is polished. At this time, the polishing tool 10 is oscillated and moved in a horizontal plane so that the entire surface of the semiconductor wafer W is uniformly polished. Further, during polishing of the semiconductor wafer W, the slurry is supplied to the contact surface between the semiconductor wafer W and the polishing pad 13 by a slurry supply device (not shown) (a part of the process working unit 70 as described above) and polished. Improve efficiency and remove shavings.

  When the polishing control unit 60 detects that the polishing of one semiconductor wafer W has been completed, the polishing control unit 60 issues an instruction to the process working unit 70 to carry the semiconductor wafer W out of the polishing apparatus 1 after polishing. Then, the semiconductor wafer W to be polished is newly carried out to the polishing apparatus 1. Then, the polishing of the semiconductor wafer W as described above is repeated. When a semiconductor wafer W to be polished is newly carried in, dressing (sharpening) of the polishing pad 13 is performed before the polishing of the semiconductor wafer W is started.

  As described above, the polishing apparatus 1 according to the present embodiment has the dress position P () in the adjusting process before starting a series of polishing processes for continuously polishing a plurality of objects to be polished (semiconductor wafers W) with the polishing tool 10. means (polishing controller 60) for setting gain values (speed gain Kv and position gain Kp) in the control of (n-1) according to the dress rate Rd (n-1), and dressing time t (n-1). Means (polishing control unit 60) for setting according to the dress rate Rd (n-1) is provided.

  According to such a configuration, since the gain value is set according to the dress rate, even if the dress rate becomes high, the amount of cutting (break-in amount) of the polishing pad 13 is prevented from becoming larger than the setting. It becomes possible. As a result, since the increase in the number of replacements of the polishing pad 13 can be suppressed without reducing the amount of the polishing object that can be polished with one polishing pad 13, the throughput of the entire polishing process can be improved.

  Further, conventionally, when the dress rate is high, the dress may be excessive and the time required for the adjustment process may become long. As a result, the throughput of the entire polishing process may be reduced. On the other hand, according to the present embodiment, since the dressing time is set according to the dress rate, it is possible to avoid an increase in the time required for the adjustment process even if the dress rate is high, Throughput of the entire polishing process can be improved.

  Here, FIG. 7 shows the relationship between the scraping amount (break-in amount) of the polishing pad 13 and the dress rate. As shown in FIG. 7, in this embodiment, it can be seen that the amount of cutting (break-in amount) is stable even when the dress rate is increased, as compared with the conventional polishing apparatus. FIG. 8 shows the relationship between the time required for the adjustment process (adjustment time) and the dress rate. As shown in FIG. 8, in the present embodiment, it can be seen that the time required for the adjustment process (adjustment time) is stable even when the dress rate is increased, as compared with the conventional polishing apparatus.

  In the polishing apparatus 1 of the present embodiment, the provisional shape keep position Pf used for setting the dress position P (n-1) is an average of the temporary shape keep positions calculated each time the shape of the polishing pad 13 is measured. The value is used. In this way, the provisional shape keep position Pf can be calculated more accurately, and the dress position can be controlled more appropriately, thereby further improving the throughput of the entire polishing process. it can.

  Further, in the polishing apparatus 1 of the present embodiment, as can be seen from the flowcharts of FIGS. 3 and 4, the conditions under which the shape of the polishing pad 13 (unevenness displacement δ) is substantially the same as the target shape (target unevenness displacement δT) are predetermined. Satisfying the number of times continuously (steps S8 to S10) and satisfying the condition that the number of valid data among the measurement data acquired by the pad shape measuring instrument 20 is equal to or greater than a predetermined number (threshold) (step S26). In addition, when the condition that the amount of cutting of the polishing pad 13 exceeds a predetermined amount (target cutting amount BT) is satisfied (step S26), the adjustment process is normally terminated. As described above, the end determination can be performed under the minimum conditions by using the uneven displacement of the polishing pad 13 and the amount of cutting (break-in amount), thereby further improving the throughput of the entire polishing process. Can be improved.

  Next, an embodiment of a semiconductor device manufacturing method according to the present invention will be described. FIG. 9 is a flowchart showing a semiconductor device manufacturing process. When the semiconductor manufacturing process is started, first, in step S200, an appropriate processing step is selected from the following steps S201 to S204, and the process proceeds to any step. Here, step S201 is an oxidation process for oxidizing the surface of the wafer. Step S202 is a CVD process for forming an insulating film or a dielectric film on the wafer surface by CVD or the like. Step S203 is an electrode forming process for forming electrodes on the wafer by vapor deposition or the like. Step S204 is an ion implantation process for implanting ions into the wafer.

  After the CVD process (S202) or the electrode formation process (S203), the process proceeds to step S205. Step S205 is a CMP process. In the CMP process, the polishing apparatus 1 according to the present invention performs damascene formation by planarizing the interlayer insulating film, polishing the metal film on the surface of the semiconductor device, polishing the dielectric film, and the like.

  After the CMP process (S205) or the oxidation process (S201), the process proceeds to step S206. Step S206 is a photolithography process. In this step, a resist is applied to the wafer, a circuit pattern is printed on the wafer by exposure using an exposure apparatus, and the exposed wafer is developed. Further, the next step S207 is an etching process in which a portion other than the developed resist image is etched away, and then the resist is peeled off to remove the unnecessary resist after etching.

  Next, in step S208, it is determined whether all necessary processes are completed. If not completed, the process returns to step S200, and the previous steps are repeated to form a circuit pattern on the wafer. If it is determined in step S208 that all processes have been completed, the process ends.

  In the semiconductor device manufacturing method according to the present invention, since the polishing apparatus 1 according to the present invention is used in the polishing process (CMP process) of the semiconductor wafer W, the throughput of the polishing process of the semiconductor wafer W is improved, and the conventional semiconductor device A semiconductor device can be manufactured at a lower cost than the manufacturing method. Note that the polishing apparatus 1 according to the present invention may be used in a CMP process other than the semiconductor device manufacturing process. Further, since the semiconductor device according to the present invention is manufactured by the semiconductor device manufacturing method according to the present invention, it becomes a low-cost semiconductor device.

  Although the preferred embodiments of the present invention have been described so far, the scope of the present invention is not limited to those shown in the above-described embodiments. For example, the polishing apparatus 1 according to the above-described embodiment is a polishing tool in which the surface of a polishing object attached to the upper surface side of the turntable 40 is positioned above the turntable 40 and the polishing pad 13 is provided on the lower surface thereof. However, the surface of the object to be polished attached to the lower end of the spindle may be polished with the polishing pad attached to the upper surface side of the rotary table located below the surface. The object to be polished by the polishing apparatus 1 according to the present invention, that is, the object to be polished is not limited to a semiconductor wafer, and may be another object such as a liquid crystal substrate.

It is a typical block diagram which shows the structure of a grinding | polishing apparatus. It is a figure which shows the relationship between a dress position and the shape of a polishing pad, (A) is when a dress position is larger than a shape keep position, (B) is when a dress position is equal to a shape keep position, (C) is a dress. The case where the position is smaller than the shape keep position is shown. It is a flowchart which shows the adjustment process in a grinding | polishing apparatus. It is a flowchart which shows the 1st process in an adjustment process. It is a flowchart which shows the 2nd process in an adjustment process. It is a flowchart which shows the 3rd process in an adjustment process. It is a graph which shows the relationship between a break-in amount and a dress rate. It is a graph which shows the relationship between adjustment time and a dress rate. It is a flowchart which shows an example of the semiconductor device manufacturing method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Polishing apparatus 10 Polishing tool 13 Polishing pad 20 Pad shape measuring device (pad shape measuring means)
30 dresser 40 turntable (polishing object holding means)
60 Polishing control unit (pad processing control means, gain setting means, dressing time setting means,
Dress position setting means, adjustment process end means)
W Semiconductor wafer (object to be polished)

Claims (5)

A polishing tool to which a polishing pad is attached; a polishing object holding means for holding a polishing object; and the polishing pad in contact with the polishing object held by the polishing object holding means. In a polishing apparatus for polishing the surface of the polishing object by relatively moving a polishing tool and the polishing object holding means,
A dresser for dressing the polishing pad by contacting a rotated dress surface with the surface of the polishing pad attached to the polishing tool;
Pad shape measuring means for measuring the shape of the polishing pad attached to the polishing tool;
In a polishing pad shape creation step before starting a series of polishing steps for continuously polishing a plurality of objects to be polished by the polishing tool, the dressing of the polishing pad by the dresser and the polishing pad by the pad shape measuring means By alternately repeating the shape measurement, data indicating the relationship between the dress position represented by the distance between the rotation axis of the polishing pad and the rotation axis of the dresser and the shape change of the polishing pad is obtained. While having a pad processing control means for processing the polishing pad into a predetermined target shape while controlling the dress position,
In the polishing pad shape creation step, gain setting means for setting a gain value in the dress position control according to the dress rate calculated when the shape measurement is performed by the pad shape measuring means;
A polishing apparatus comprising: a dressing time setting unit configured to set a dressing time of the polishing pad by the dresser according to the dressing rate in the polishing pad shape creation step. In the polishing pad shape creation step, based on the data indicating the relationship between the dress position and the shape change of the polishing pad, the temporary shape that is the dress position at which the change rate of the uneven displacement of the polishing pad becomes substantially zero A dress position setting unit configured to calculate a keep position and set a dress position that minimizes a change in the shape of the polishing pad based on the temporary shape keep position;
2. The polishing apparatus according to claim 1, wherein the temporary shape keep position is an average value of the temporary shape keep positions calculated each time the shape measurement is performed by the pad shape measuring unit.   In the polishing pad shape creation step, a condition that the shape of the polishing pad measured by the pad shape measuring means is substantially the same as the target shape is continuously satisfied a predetermined number of times, and the pad processing control means Satisfying the condition that the number of valid data among the data acquired by the above is a predetermined number or more, and satisfying the condition that the polishing amount of the polishing pad exceeds a predetermined amount, the polishing pad shape creation step The polishing apparatus according to claim 1, further comprising a polishing pad shape creation process ending means for ending. The polishing object is a semiconductor wafer;
A semiconductor device manufacturing method comprising a step of planarizing a surface of the semiconductor wafer using the polishing apparatus according to claim 1.   A semiconductor device manufactured by the semiconductor device manufacturing method according to claim 4.

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