JP2001260001A - Semiconductor device planarization method and device - Google Patents

Abstract

(57) Abstract: In a polishing process, a scratch density on a polished surface is reduced. A dress rate measuring device detects a dress rate of a polishing pad that changes with the progress of polishing.
And surface shape measuring device 1 for measuring polishing pad surface properties
0, the polishing platen torque and the dresser driving torque are obtained by converting the current value flowing to each of the motors 7 and 9 by the A / D converter 13, and the scratch density is determined by using these data automatically measured in real time. The dressing conditions are controlled so that the dress rate that has a significant effect on the value falls within the range of the management specified value previously obtained and stored in the database 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for planarizing an interlayer insulating film and a metal film formed on a substrate of an integrated circuit. The present invention relates to a flattening method and a flattening apparatus capable of reducing defects on the entire surface of a wafer.

[0002]

2. Description of the Related Art In the course of the process of forming a high-density semiconductor integrated circuit device, the surface of a Si wafer has complicated irregularities due to the patterning of an insulating film or a metal film. When a pattern is continuously formed on the surface of the Si wafer having the unevenness, the resolution in the pattern transfer is insufficient due to the lack of the depth of focus in the lithography process, and the metal wiring film is damaged at the step portion of the unevenness. In some cases, this may be an obstacle in producing a high-density semiconductor integrated circuit. Therefore, as one step in the semiconductor device manufacturing process, CMP (Chemical Mechanical Polishing) for flattening the irregularities has been introduced.

Conventionally, in the above-described polishing process of a Si wafer by CMP or the like, in order to grasp a change in the defect density of the polishing surface due to abrasion of the polishing pad surface due to the progress of polishing, every time a predetermined number of Si wafers are polished, The defect density is measured using a dummy substrate. Specifically, the defect density (the number of scratches per unit area) of the Si oxide film formed on the dummy substrate surface after polishing is measured.
When the deviation is out of the target defect density management standard, the dresser is replaced and the polishing pad is replaced.

[0004] In addition, in order to maintain the polishing efficiency constant,
The polishing efficiency is measured by a dummy substrate every time a predetermined number of Si wafers are polished, and the value obtained by dividing the required time is determined as the polishing efficiency, and the polishing efficiency falls below a predetermined value due to wear of the polishing pad surface. In this case, a method of performing a dressing process (a process of repairing the polishing pad surface smoothed by abrasion or the like using a diamond grindstone or the like using a diamond grindstone) for repair to suppress the fluctuation range of the polishing efficiency is disclosed in, for example, JP-A-9-285555. This is implemented as shown in the official gazette.

[0005]

However, in order to manage the defect density on the polished surface in the prior art, it is necessary to frequently perform the measurement using the dummy substrate described above.
As a result, there is a disadvantage that the manufacturing efficiency of the semiconductor device is reduced.

It is an object of the present invention to control a dressing condition of a dressing grindstone for creating a surface shape of a polishing cloth and to suppress a defect density (scratch density) on a polished surface of a workpiece. And a flattening device.

[0007]

According to the present invention, at least one of a dressing rate of a polishing pad and a surface state thereof is directly or indirectly controlled during polishing or dressing after polishing. And controlling the dressing conditions so that the obtained data satisfies the management specified conditions set based on the correlation between the defect density and the dress rate or the polishing cloth surface condition that are obtained in advance. Features.

[0008]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

First, the basic configuration of a polishing apparatus according to the present embodiment will be schematically described with reference to FIG. In this embodiment, a polishing apparatus of the same type as a polishing apparatus for performing CMP or the like, which is one of the semiconductor device manufacturing processes described in the section of the prior art (that is, a polishing platen 3 on which a polishing pad 4 is attached). Is rotated by a motor 9 so as to slide the wafer 1 and the polishing pad 4 at an arbitrary polishing pressure. Here, a description will be given mainly of the configuration characteristic of the present polishing apparatus.

The present polishing apparatus has a well-known basic structure as a polishing apparatus, and is further rotated by a driver 8 of a driving motor 7 of a dresser 5 generated when dressing the polishing pad 4 attached to the polishing platen 3. A / D converter 13 for measuring driving force and driver 1 for driving motor 9 of polishing table 3
2, an A / D converter 13 for measuring the rotational driving force, a surface shape measuring device 11 for measuring the surface condition of the polishing pad 4 described later, and a dress rate measuring device 10 for the polishing pad 4.
And a dress rate for each product specification, a database 15 in which information on a correlation between a polishing pad surface property and a defect density after polishing is recorded in advance, and an information processing device 14 for executing an evaluation process, control of the entire device, and the like. A controller 6 for controlling the polishing pressure and the like of the dressing grindstone;

Hereinafter, each component of the polishing apparatus shown in FIG. 1 will be described in detail.

First, defects on a polished surface of a semiconductor device which may be caused by a polishing process will be described. FIG. 2 shows an example of a defect on the polished surface after polishing the oxide insulating film of the semiconductor device and then cleaning it with a cleaning liquid having an etching action, and the defect 15 ′ is a defect (scratch) on the polished surface. If such scratches occur on the polished surface,
When a conductive wiring material is formed after the CMP process, the wiring material penetrates into the scratches, causing a short circuit between the wirings and lowering the yield of the semiconductor device. For this reason, it is important to minimize the scratches, but it is practically impossible to eliminate them at all. Therefore, it is important to set and manage a defect density, that is, a scratch density management standard for a desired yield.

Next, in order to clarify what kind of physical quantity should be managed in order to make the above-mentioned scratch be included in the management standard, the cause of scratch generation will be described.

FIG. 3 shows a scratch generation model. The conceptual diagram of the CMP is shown in the upper left of FIG. 5 by surrounding the frame 1 with a frame A. The wafer 1 is mounted on the wafer holder 2, the processing surface is turned downward, and the polishing pad 4 is rotated in the direction of arrow b, and is rotated in the direction of arrow c. Is pressed onto the surface of the polishing pad 4
Is polished by being dropped on the surface of the substrate. At the same time, on the opposite side of the polishing point of the wafer 1 on the polishing pad 4, the dresser 5 is rotated in the direction of arrow a to prevent the polishing pad 4 from being worn out. Then, the surface of the polishing pad 4 is dressed.

An ordinary polishing pad 4 has many holes 41 as shown in the figure, and the diameter 41a is about 50 μm. The abrasive grains 17 contained in the slurry are held in a concave portion formed by a hole exposed on the surface of the polishing pad 4 or in a portion of the polishing pad surface having a moderate roughness.
Is polished. However, flattened portions are formed on the surface of the polishing pad 4, and the agglomerated abrasive grains 18 having a particle size of 1 μm or more different from ordinary slurry having an average particle size of 0.1 to 0.2 μm are formed thereon. Intervening, excessive stress concentration occurs on the wafer surface, and scratches 1
5 'occurs.

As a method for reducing the above-mentioned scratches, it is necessary to control the dressing conditions of the dresser 5 so as to reduce the number of agglomerated abrasive grains 18 or to prevent blinding occurring on the surface of the polishing pad 4. It is valid.
Generally, when a wafer is polished using the same polishing pad, a tendency is observed that the density of scratches increases as the number of processed wafers increases, as shown in FIG. Next, data obtained by taking this phenomenon as a change in the polishing pad surface state will be described.

FIG. 5 shows the correlation between the number of processed wafers and the ratio of the area in contact with the polishing surface of the wafer to the polishing pad surface area, that is, the true contact area ratio, and the Young's modulus which is an index of the hardness of the polishing pad. . The method of measuring the true contact area ratio will be described later. As the number of processed wafers increases, the true contact area ratio and the Young's modulus of the pad increase, and it can be seen that a planar portion due to blinding is formed on the polishing pad surface.

FIGS. 6 and 7 show scanning electron microscope photographs of the polishing pad surface when the number of processed wafers surrounded by the ellipse E in FIG. 5 is small and the number of processed wafers is large. Show. In FIG. 6, uniform dressing is performed over the surface of the polishing pad, and it can be seen that a flat portion due to blinding is not formed. However, it is observed that many flat portions due to blindness are formed on the polishing pad surface where the number of processed wafers shown in FIG. 7 is increased. From this, the cause of the increase in the true contact area ratio shown in FIG. 5 is apparent.

That is, by measuring the true contact area ratio, it is possible to detect in real time an increase in the planar portion of the pad surface which may cause scratches.

Next, an apparatus for measuring the above-described true contact area ratio of the polishing pad will be described.

FIG. 8 shows details of the pad surface shape measuring apparatus 11 shown in the apparatus configuration diagram of the present invention shown in FIG. Examples of the pad surface shape measuring device 11 include those using an image processing method and a reflectance method. In the image processing method,
The surface of the polishing pad 4 is illuminated by a projector 20 driven by a power supply 19, an image of the location is extracted by a CCD camera 21, the data is taken into an information processing device 14 via an amplifier 22, and image processing is performed. Then, the area ratio of the plane portion formed by the blindness shown in FIG. 7 is calculated.

In the reflectivity method, as shown in FIG. 8, a laser beam emitted from a laser light source 23 is applied to a pad surface, and the reflected light is received by a light receiver 24. You can also ask.

In the present embodiment, as long as the surface shape of the pad can be measured during the polishing process, a pad surface shape measuring device other than the above-described method may be used.

Further, a method of measuring the above-mentioned dress rate, that is, a pad dress amount per unit time, and a specific example of the dress rate measuring apparatus 10 shown in the apparatus configuration diagram of the present invention shown in FIG. 1 will be described. FIG. 9 shows details of the dress rate measuring device 10 shown in the device configuration diagram according to the present invention in FIG.

A groove 42 for supplying and discharging slurry is formed on the surface of the polishing pad 4 used in a normal CMP apparatus. Mini XZ table 2
5, using a laser displacement meter 26 attached to
The data is fetched into the information processing device 14 and arithmetic processing is performed to calculate a dress rate from a change in thickness of the polishing pad 4 per unit time from a change in depth.

With respect to the calculation of the dress rate, an A / D converter 13 for measuring the rotational driving force by the driver 8 of the driving motor 7 of the dresser 5 shown in FIG. Drive motor 9 for surface plate 3
The current value of each drive motor using an A / D converter 13 for measuring the rotational driving force from the driver 12 is measured and input to the information processing device 14, and the monitoring data of the dress state can be used at the same time. Desirable (see FIG. 1).

FIG. 10 shows an A / D measuring the rotational driving force by the driver 8 of the driving motor 7 of the dresser 5 shown in FIG.
This is an example of measuring current values of respective drive motors using a D converter 13 and an A / D converter 13 for measuring a rotational driving force by a driver 12 of the drive motor 9 of the polishing table 3. With respect to the polishing time of the polishing platen torque signal indicated by the arrow d1, the change in the current value of the drive motor 9 of the polishing platen 3 due to the swing of the wafer holder is measured as indicated by the arrow e, and the lower dresser torque is measured. Similarly, a change as shown by an arrow d2 is measured in the signal.

A platen driving signal at the time indicated by an arrow f in which only dressing after polishing is completed, and an arrow g
It can be seen that the drive signal when in contact with the dresser cleaning pad when the dresser is evacuated can be measured as a negative torque. This is because the rotation of the polishing platen is larger than the rotation of the dresser during dressing, so that the dresser drive motor generates a torque in the direction opposite to the rotation direction to apply the brake in order to maintain the set rotation.

As described above, it is possible to measure the drive motor current value of the polishing platen and the dresser as the rotational torque. A correlation between the rotational torque (measured current value) and the dress rate is obtained in advance, and a converted dress rate can be obtained from the correlation and the measured current value. Note that the correlation between the rotational torque and the dress rate is usually in a linear relationship.

Further, the converted dress rate obtained in this manner is used together with the dress rate measured from the change in the depth of the polishing pad groove as in the above-described dress rate measuring apparatus 10 or the like, so that the measured value of the dress rate can be obtained. Accuracy can be improved. Specifically, for example, by using the average dress rate obtained from the measured dress rate calculated from the change measurement of the pad groove depth, the correlation coefficient between the rotational torque and the dress rate is corrected, and the converted dress rate is calculated. Accuracy can be improved.

As described above, a more accurate dress rate can be obtained from the improved converted dress rate and the dress rate measured from the change in the depth of the pad groove.

Next, a description will be given of the functional structure of the database 15 in which the correlation between the dress rate for each product specification, the surface properties of the polishing pad, and the defect density after polishing shown in FIG. 1 is recorded in advance.

First, in order to reduce scratches on the polishing surface, it is necessary to suppress the generation of flat portions due to blind spots on the polishing pad. For this reason, the present inventor has clarified that preventing the above-described increase in the true contact area ratio, that is, improving the dressing ability is effective for reducing scratches. FIG. 11 shows the relationship between the dress rate and the scratch density measured based on the method described above. The figure shows that there is a correlation between the dress rate and the scratch density, and it can be seen that the scratch density can be reduced by increasing the dress rate. This relationship varies depending on the specifications of the semiconductor device product to be polished. In this embodiment, the data of each specification is shown in FIG.
Is stored in the database 15 shown in FIG.

In the database 15 of the present embodiment, for example, for each specification of each semiconductor device product to be polished, an allowable defect density value or a management specified value set corresponding to each of various defect density values is set. The minimum value of the dress rate and the maximum value of the true contact area ratio are stored.

The polishing apparatus of the present invention was constructed based on the results described above. Next, examples and effects when polishing is performed using the apparatus of the present invention will be described.

[0036]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In a polishing process under the following polishing conditions using the polishing apparatus of the present invention shown in FIG.
The Si wafer (150 mm in diameter) on which the i-oxide film was formed was polished using a polishing pad (thickness: about 1 mm) mainly composed of foamed polyurethane having a compression modulus of 100 Mpa. (1) Slurry: aqueous solution with 12% SiO ₂ abrasive content (2) Slurry supply rate: 100 ml / min (3) Polishing pressure: 500 g / cm ² (4) Rotation speed of polishing platen: 300 mm / s (5) ) Rotational angular velocity of Si wafer: 126 rad / min The polishing process proceeds in a processing procedure as schematically shown in FIG. That is, polishing and dressing are performed simultaneously (steps 1301 to 1302). When polishing for a predetermined number of sheets is completed (step 1303), the defect density is measured (step 1304). If the defect density is within a specified value, polishing is performed. Is resumed (Y in step 1305), and when it exceeds the specified value (N in step 1305), dressing conditions such as drive torque are corrected to dress the polishing pad.

In this embodiment, the case where the polishing and the dressing are performed simultaneously will be described. However, the present invention can be applied to the case of the intermittent dressing in which the dressing is performed after the polishing of a predetermined number of sheets. Can be.

The dressing process shown in FIG.
02), as shown in FIG. 14, a dresser 5 generated when dressing the polishing pad 4 attached to the polishing platen 3 is formed.
An A / D converter 13 for measuring a rotational driving force from a driver 8 of a driving motor 7 of the above, and an A / D converter 1 for measuring a rotational driving force from a driver 12 of a driving motor 9 of the polishing platen 3
3, the torque signal calculated from the current values of the respective drive motors measured by the above, the true contact area ratio data on the surface of the polishing pad 4 measured by the surface shape measuring device 11, the dress rate measured by the dress rate measuring device 10. The data is taken into the information processing device 14. The information processing device 14 acquires a high-accuracy dress rate from the converted dress rate converted from the rotational torque data and the dress rate measured by the dress rate measuring device 10 (steps 1402 to 1403).

Next, the information processing device 14 obtains the acquired dress rate data and the measured true negotiated area ratio data, and shows an example of the dress rate for each product specification shown in FIG.
The data of the database 15 in which the correlation between the polishing pad surface property expressed by the true contact area ratio and the defect density after polishing is compared in advance is compared (step 1404). If the measured data is within the specified range (step 1404)
Return to step 1402 to re-measure and re-acquire the data. If it is not within the specified range (Step 1
(NG at 404) It is checked how many times the measurement data has deviated from the specified range in this manner (step 1405).

If the deviation from the specified range is not continuous (first time in step 1405), the controller 6 controls the dressing pressure of the dressing whetstone by the controller 6 by the information processing device 14 for controlling the entire device. The dressing conditions are corrected by controlling (step 1406), and step 14
Return to 02. More specifically, for example, when one of the values of the dress rate and the true contact area ratio is lower than the specified value of the dress rate corresponding to the desired defect density stored in the database 15 Or, when it becomes higher than the specified value of the true contact area ratio, control is performed to increase the dress pressure.

If the desired dress rate and the surface properties of the polishing pad cannot be controlled only by the dress pressure, that is, if NG has been reached for the second consecutive time (step 14).
05 (second time), the drive torque of the polishing pad rotation drive motor 9 and the dresser rotation drive motor 7 is controlled, and the process returns to step 1402. For example, the drive torque is increased by lowering the rotation speed. Alternatively, the dressing sequence itself may be changed so that the polishing being performed is temporarily stopped and only the dressing is performed to obtain a desired polishing pad surface state.

The above control is generally performed according to product specifications,
Polishing pad material, slurry material and abrasive content,
It changes under the influence of the polishing conditions and the like. For this reason, it is preferable that the influence on the control is obtained in advance, and the control is corrected for each material and polishing condition in consideration of the obtained influence.

The above-mentioned control is, for example, created as a computer-executable program, and
It can be realized by causing the information processing device 14 configured by a computer system including a U and a memory to execute the program.

Further, in the present embodiment, FIGS.
In addition to the processing described above, the dressing performance of the polishing pad during polishing is evaluated based on the dress rate and the polishing pad surface properties that are sequentially calculated. And
When the above control falls below a certain effect, when the dressing performance of the polishing pad has deteriorated, or when the groove depth of the polishing pad has become less than a certain value, it is determined that the polishing pad has reached the life.

FIG. 12 shows the relationship between the number of processed wafers and the scratch density when a semiconductor device is actually processed using this polishing apparatus. The data when the control of this apparatus is not performed is indicated by black circles. Compared with this data, when the function of this apparatus is used, the scratch density is 0.5 / cm ² or less, confirming the effect of the device of the present invention.

The description of the embodiment has been completed.

Here, the effects obtained by employing the present polishing apparatus in the flattening polishing step in the semiconductor manufacturing process will be summarized.

Automatically measure in real time the dressing rate of the polishing pad, the surface properties of the polishing pad, the polishing surface plate torque, and the dresser driving torque that change with the progress of the polishing process, and control the dressing rate that has a significant effect on the scratch density. Without having to spend time and effort.
The scratch density, which changes with the progress of the polishing process, can be kept low. Such effects derive the following effects and further improve the performance of semiconductor devices such as LSIs as final products.

(1) Since the dressing process of the polishing pad can be optimized, the polishing performance of the polishing pad can always be maintained at a constant level.

(2) Since the defect density on the polished surface can be stably reduced, the yield of semiconductor devices can be improved.

Further, since the scratch density can be estimated without stopping the polishing process line, there is also a second effect that the production efficiency of the Si wafer is not reduced.

In the present embodiment, the Si wafer is polished, but the same effect can be achieved by polishing other workpieces.

[0053]

According to the present invention, the dressing rate of the polishing pad, the surface properties of the polishing pad, the polishing platen torque, and the dresser driving torque, which change with the progress of the polishing process, are measured in real time, and the serious influence on the scratch density is measured. The given dress rate can be controlled, and the scratch density, which changes with the progress of polishing, can be kept low without taking much time and effort, so that the yield of semiconductor devices can be improved.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a basic configuration of a polishing apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory view showing an observation photograph of a scratch generated on a polished surface.

FIG. 3 is an explanatory diagram of a scratch generation model.

FIG. 4 is a graph showing an example of experimental data showing the correlation between the number of processed wafers and the scratch density.

FIG. 5 is a graph showing an example of experimental data showing the correlation between the number of processed wafers, the ratio of the true contact area of the polishing pad surface, and the Young's modulus of the polishing pad.

FIG. 6 is an explanatory view showing a scanning electron micrograph of the polishing pad surface at the initial stage of polishing in experimental data showing the correlation between the number of processed wafers, the ratio of the true contact area of the polishing pad surface, and the Young's modulus of the polishing pad.

FIG. 7 is an explanatory diagram showing a scanning electron micrograph of a closed polishing pad surface at the latter stage of polishing in experimental data showing a correlation between the number of processed wafers, the true contact area ratio of the polishing pad surface, and the Young's modulus of the polishing pad.

FIG. 8 is an explanatory view showing details of a pad surface shape measuring device.

FIG. 9 is an explanatory diagram showing details of a dress rate measuring device.

FIG. 10 is a graph showing an example of experimental data obtained by measuring a rotational driving force of a driving motor of a dresser and a rotational driving force of a driving motor of a polishing table.

FIG. 11 is a graph showing an example of experimental data showing a correlation between a dress rate and a scratch density.

FIG. 12 is a graph showing an example of the relationship between the number of processed wafers and the scratch density when a semiconductor device is actually processed using the polishing apparatus.

FIG. 13 is a flowchart showing a processing example of a polishing / dressing process of the present polishing apparatus.

FIG. 14 is a flowchart illustrating a control example of the dressing process of FIG. 13;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Wafer, 2 ... Wafer holder, 3 ... Polishing table, 4 ... Polishing pad, 5 ... Dresser, 6 ... Dresser polishing pressure controller, 7 ... Dresser drive motor, 8 ... Dresser drive motor driver, 9 ... Drive of polishing board motor,
10: Dress rate measuring device, 11: Surface shape measuring device, 12: Driving motor driver of polishing platen, 13: A
/ D converter, 14 ... information processing device, 15 ... database, 15 '... scratch, 16 ... slurry, 17 ... abrasive grains, 18 ... agglomerated abrasive grains, 19 ... light projector power supply, 20 ... light projector, 21 ... CCD camera, 22 ... Amplifier, 23 ... Laser light source, 24 ... Receiver, 25 ... Mini XZ table, 26
... laser displacement meter, 41 ... holes in polishing pad, 41a ...
Hole diameter, 42 ... grooves on polishing pad surface, 51 ... diamond.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroyuki Kojima 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Inside the Hitachi, Ltd. Production Technology Research Institute (72) Inventor Tetsuo Okawa 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa F term in Hitachi, Ltd. Production Engineering Laboratory (reference) 3C034 AA13 BB93 CA22 CA30 CB12 DD05 3C058 AA07 AA19 AC02 BA09 BA14 BB02 BB06 BC02 CB01 DA12 DA17

Claims (8)

[Claims] 1. A method of flattening a semiconductor device in which a polishing cloth is dressed during or after polishing, wherein a dress rate of the polishing cloth is directly or indirectly obtained during the dressing. The dressing condition of the polishing pad is adjusted so as not to be less than a predetermined value, and the predetermined value is a dress rate value corresponding to a maximum allowable defect density. A method for planarizing a semiconductor device. 2. A flattening method for a semiconductor device, wherein a polishing cloth is dressed during or after polishing, wherein a surface state of the polishing cloth is measured during the dressing, and the measured surface state of the polishing cloth is predetermined. Adjusting the dressing condition of the polishing pad so as to satisfy the specified condition, wherein the predetermined condition is a surface state corresponding to a case where an allowable defect density shows a maximum value. A method for planarizing a semiconductor device, comprising: 3. A method of flattening a semiconductor device in which a polishing cloth is dressed during or after polishing, wherein a dress rate of the polishing cloth is directly or indirectly determined during the dressing, and the polishing is performed during the dressing. Measuring the surface condition of the cloth, and adjusting the dressing conditions of the polishing cloth so that the determined dress rate and the measured surface state of the polishing cloth satisfy a predetermined condition. Among the predetermined conditions, the dress rate is a dress rate value corresponding to the maximum value of the allowable defect density, and the surface condition of the polishing cloth is a case where the allowable defect density indicates the maximum value. A planarization method for a semiconductor device, characterized in that the surface state is changed. 4. A flattening apparatus for a semiconductor device, a dress rate obtaining means for obtaining a dress rate during a dressing process, wherein the obtained dress rate is equal to or more than a reference value determined according to a defect on a polishing cloth surface. A flattening device for a semiconductor device, comprising: control means for controlling dressing conditions. 5. The flattening device according to claim 4, further comprising a surface state measuring means for measuring a surface state of the polishing pad during the dressing process, wherein said control means controls the dressing rate. And a dressing condition is controlled so that the measured surface state of the polishing cloth satisfies a reference condition determined according to a defect of a polished surface. 6. A flattening apparatus according to claim 4, wherein said dress rate obtaining means detects a rotational driving force of the dressing grindstone and calculates a converted dress rate from the detected rotational driving force. A calculating means, a dress rate detecting means for directly detecting a dress rate by detecting a thickness change per unit time of the polishing pad, and using at least one of the obtained two dress rates, during the dressing process. A flattening apparatus for a semiconductor device, comprising: a dress rate determining means for determining a dress rate. 7. The flattening apparatus according to claim 5, further comprising a database in which a correlation between a defect density and a dress rate and a correlation between the defect density and a surface state of the polishing pad are recorded. A flattening apparatus for a semiconductor device, wherein a dressing condition is controlled based on the data of the database and the acquired dress rate and polishing cloth surface state so that a defect density falls within a management reference value. 8. A method for manufacturing a semiconductor device, comprising at least a flattening step for flattening surface irregularities generated in a wiring pattern forming step, wherein the flattening step is performed according to claim 1. A method for manufacturing a semiconductor device, which is performed by a planarization method.