JP2001237206A - Flattening method - Google Patents

Abstract

(57) [Problem] To provide a flattening method for uniformly polishing a workpiece. SOLUTION: When the surface to be processed of the workpiece is polished and flattened by a polishing pad, at least 2
(1) Position the polishing pad on the work surface so that a part of the work surface is exposed from the polishing pad; (2) Contact the work surface with the polishing pad To create a pressure between them; and (3)
By oscillating the polishing pad and rotating the work piece around its center axis as a rotation axis, the work surface is polished, and by changing the residence time of the polishing pad for each position, the work The processing amount at each position on the surface is set to a desired amount.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for flattening a surface of a workpiece by polishing, and more particularly to a method of forming a wiring on a surface of a semiconductor device by forming a wiring on a surface of the semiconductor device. The present invention relates to a flattening method suitable for flattening an insulating material layer formed on a wiring.

[0002]

2. Description of the Related Art In recent years, processing methods for flattening a processing surface of a processing object by polishing have been applied in various fields. As one example, a flattening process in a wiring process of a semiconductor device can be cited.

The wiring process of a semiconductor device is performed as follows. First, a wiring made of a conductive material such as aluminum is formed on a semiconductor substrate; an insulating oxide film is laminated; and the insulating oxide film is polished and flattened. The planarization of the insulating oxide film is necessary for forming a desired circuit pattern in a photolithography process. If there are irregularities on the surface of the insulating oxide film and the level difference is large,
There are portions of the resist that are not properly focused. As a result, there arises a problem that a desired circuit pattern is not formed.

Further, when wiring is further formed on an insulating oxide film having irregularities, the thickness of the wiring material is reduced at the step portion,
In an extreme case, the film may be interrupted and become disconnected. As another problem, when a wiring material is patterned on an insulating oxide film having an uneven surface, the wiring material may not be easily etched at a step portion. In an extreme case, a short-circuit state occurs.

In order to avoid such a problem, for example, an etching back method or a fluidization method in which SOG or reflow is applied and then a heat treatment is performed is employed to planarize the insulating oxide film. I have. However, both the etch-back method and the fluidization method may or may not be processed depending on the type of the insulating film. Further, they only realize partial flattening, but cannot realize overall flattening.

Recently, instead of these conventional flattening methods, polishing methods, in particular, chemical mechanical polishing (chemical mechanical polishing method; CM) involving a chemical reaction between an insulating film and an abrasive have been proposed.
P) is being adopted. According to CMP, the entire surface of the insulating oxide film can be made extremely smooth.

Separately, the following wiring process is performed in the manufacturing process of a semiconductor device. First, a groove is provided in a semiconductor substrate, a film of a conductive material is formed so that the conductive material is embedded in the groove, and the surface of the film of the conductive material is planarized. This planarization is performed such that the top surface of the conductive material in the groove and the top surface of the substrate are flush with each other to ensure insulation of the conductive material in the adjacent groove. Also in this case, a polishing method, in particular, CMP is adopted as a flattening method.

An example of an apparatus for polishing a surface to be processed having fine irregularities, such as a semiconductor device, is disclosed in Japanese Patent Application Laid-Open No. Hei 7-2017788. A method of using the device disclosed in the publication will be described with reference to FIG. First, the disk-shaped workpiece (5) is fixed to a rotatable table (6) with the workpiece surface (5a) facing upward. Next, a disk-shaped polishing pad (1) is attached to the polishing pad holder (3) that can rotate. The surface of the polishing pad holder (3) to which the polishing pad (1) is attached is formed of an elastic material (2).

The polishing pad (1) and the work surface (5a)
The two rotating shafts are shifted, and a gap is provided between the two. Then, a polishing slurry is supplied between the polishing pad (1) and the surface to be processed (5a) as necessary, whereby the polishing pad (1) and the workpiece (5) are rotated, and the polishing pad (1) is rotated. Is reciprocated in the radial direction of the processing surface (5a). Subsequently, a gas is sent into the polishing pad holder (3), and the pressure of the gas is transmitted to the polishing pad (1) through the elastic material (2), thereby causing the polishing pad (1) to be processed. (5a) is pressed vertically to start polishing. After performing the polishing for a predetermined time, the internal pressure in the polishing pad holder (3) is released to complete the polishing of the workpiece (5). Since the rotation axis of the polishing pad (1) can be moved in the horizontal direction, by changing the distance between the axis of the workpiece (5) and the axis of the polishing pad (1),
Polishing of the central portion and the outer peripheral portion of the work surface (5a) can be performed.

[0010] In the apparatus shown in FIG.
The polishing pad is disposed on the work surface such that the diameter of the polishing pad overlaps at least one radius of the work surface, and the diameter of the polishing pad includes the radius of the work. The ratio of the number of rotations of the polishing pad (1) and the number of rotations of the workpiece (5) is set so that the amount of processing is constant over the entire surface to be processed based on the result of performing the processing in advance on a trial basis.

According to this apparatus, since the workpiece (5) and the polishing pad (1) are rotated while the rotation axis is shifted, a relative motion is generated between the workpiece and the polishing pad. (1) is designed to polish the entire surface to be processed (5a). Further, the polishing pad (1) is pressed against the surface to be processed (5a) through the polishing slurry at a constant pressure. Therefore, even when the workpiece is warped, the flattening process can be performed relatively uniformly.

The polishing time is generally determined as follows. First, the thickness of the workpiece is measured at several points (for example, 5 points or 9 points), and the amount to be removed by polishing (that is, the processing amount) is calculated from the average value of the thickness. next,
Find the polishing rate. The polishing rate depends on the type of workpiece,
Since it varies depending on the area and type (for example, material) of the polishing pad, the relative speed between the polishing pad and the workpiece, the pressure between the polishing pad and the workpiece, and the type of polishing slurry, it is generally experimentally determined. Desired. Then, the polishing time is calculated by dividing the processing amount by the polishing rate.

[0013]

Although the apparatus shown in FIG. 8 is hardly affected by the warpage of the surface to be processed, it still requires improvement. For example, on the work surface, besides mere warping, the period is several cm, and the amplitude is several μm
If there is undulation and / or if there is unevenness in the polishing surface of the polishing pad, the polishing rate on a part or all of the surface to be processed will still be a general polishing rule even if the polishing is performed by the above-described apparatus. (Preston's formula)
As a result, there is a problem that processing accuracy is deteriorated. A similar problem occurs in chemical mechanical polishing (CMP) or mechanochemical polishing (MCP) in which components in the polishing slurry chemically react with the workpiece on the workpiece surface.

Here, the "processing accuracy" is represented by a difference between a target processing amount and an actual processing amount. The greater the difference, the worse the processing accuracy. Processing amount is flattening (polishing)
Is generally represented by the thickness of the workpiece (or film) removed (polished).

Further, for example, since the thickness of the insulating oxide film formed on the semiconductor substrate (ie, the distance between the surface of the semiconductor substrate and the surface of the insulating oxide film) is not uniform, undulations exist on the surface of the surface to be processed. May be. Such undulations generally have a period (distance between the top of the undulation and the next vertex) of several c
m and a height of several hundred nm to several μm. If the surface to be processed having such undulations is polished, polishing proceeds while the undulations remain, and it tends to be difficult to completely flatten the surface to be processed.

The present invention has been made in view of such circumstances, and has as its object to provide a flattening method capable of polishing the entire surface of a workpiece more uniformly.

[0017]

In order to solve the above-mentioned problems, a flattening method according to the present invention is a flattening method for polishing and flattening a processing surface of a workpiece with a polishing pad. (A) positioning the polishing pad on the work surface such that a part of the work surface is exposed from the polishing pad; (b) the work surface and the polishing pad And (c) oscillating the polishing pad and rotating the workpiece about its central axis as a rotation axis to polish the surface to be processed. This is a flattening processing method which is performed respectively and the processing amount at one position on the surface to be processed is different from the processing amount at at least one other position.

In (a) where the polishing pad is located,
The polishing pad is located at at least two different positions on the work surface. This is performed by using one point (for example, the center of the polishing surface) of the polishing pad having the polishing surface as a reference point, and arranging the reference point at at least two different positions on the surface to be processed.

"At least two different positions" are at least two different positions when the workpiece is stationary. In the step (c) of polishing the surface to be processed, the displacement of the reference point of the polishing pad with respect to the position on the surface to be processed due to the rotation of the workpiece and the swing of the polishing pad means that the polishing pad is covered. It does not correspond to disposing at least two different positions on the processing surface.

"A part of the surface to be processed is exposed from the polishing pad" means that the workpiece and the polishing pad are stationary (that is, the polishing pad is positioned (a)), and the polishing pad is This means that the polishing pad is positioned on the surface to be processed such that there is a portion that does not overlap with the surface (that is, the polishing pad does not exist above at least a portion of the surface to be processed).

Therefore, in the flattening method of the present invention, a polishing pad having a polishing surface whose area is smaller than the area of the surface to be processed of the workpiece is preferably used. When the workpiece and the polishing pad are disk-shaped, it is preferable that the diameter of the polishing pad is smaller than the diameter of the workpiece.

"Swinging" the polishing pad means that the polishing pad is reciprocated linearly in a direction parallel to the surface to be processed (generally in a horizontal direction).

In the flattening method of the present invention, the movement of the polishing pad from one position on the surface to be processed to the next position is not continuous. Therefore, a step is likely to occur between portions to be polished when the polishing pad is at each position. In order to eliminate this step, the polishing pad is swung. The swing direction of the polishing pad is preferably a moving direction when the polishing pad moves from one position to the next position. For example, when the workpiece is a disk, the polishing pad may be sequentially moved in the radial direction of the workpiece, and may be swung in the radial direction of the workpiece. When the workpiece is rectangular, the polishing pad may be sequentially moved in a diagonal direction of the rectangular shape of the workpiece, and may be swung in a diagonal direction of the workpiece.

In the flattening method according to the present invention, the workpiece is rotated with its central axis as a rotation axis. The “center axis” of the workpiece is an axis that is perpendicular (or vertical) to the workpiece surface passing through the center of the workpiece surface of the workpiece. The rotation of the workpiece and the swinging of the polishing pad cause relative movement between the polishing pad and the workpiece to polish the workpiece surface.

Further, when the polishing pad is rotated about its central axis as a rotation axis, the relative speed between the workpiece and the polishing pad can be further increased. The “center axis” of the polishing pad is an axis perpendicular (or perpendicular) to the polishing surface passing through the center of the polishing surface of the polishing pad.

The time during which the polishing pad is in contact with the surface to be processed and the polishing pad is polishing the surface to be processed, that is, the time during which the above (c) is performed, is referred to as the “residence time of the polishing pad” in this specification. ".

As described above, the flattening processing method of the present invention is characterized in that the processing amount at one position on the surface to be processed is different from the processing amount at at least one other position. The “amount of processing” means the amount of polishing of the surface to be processed, and the thickness of the workpiece (or the distance from the surface of the film to be planarized to the surface of the substrate) before and after the flattening method of the present invention is performed. ). “The amount of processing at one position on the surface to be processed is different from the amount of processing at at least one other position” means that the amount of processing is not the same at all positions on the surface to be processed. I do. This feature allows the amount of processing to be increased or decreased as desired depending on the position of the surface to be processed on a workpiece having a non-uniform thickness, thereby making the thickness of the workpiece more uniform. Thus, the flatness of the surface to be processed can be further improved.

Assuming that the machining amount at one position on the surface to be machined is different from the machining amount at at least one other position, the machining amounts at M positions (M is an integer of 3 or more) on the surface to be machined were compared. When: When comparing the processing amount at a certain position with the processing amount at other (M-1) positions, the latter is the same as each other and the former is different from the latter; N positions (N is In the case where the processing amounts at positions of 2 or more and an integer smaller than M) are all H, and the processing amounts at (MN) positions are all H ′ and H ≠ H ′ In the case where the machining amounts at L positions (L is an integer of 2 or more and smaller than M) are all J, and the machining amounts at (ML) positions are not J; When the processing amount is different from each other And the like.

If the amount of processing at one position on the surface to be processed is different from the amount of processing at at least one other position, when the amount of processing at a plurality of points on the surface to be processed is measured, two arbitrary processings are performed. When a set of quantities is selected, a case where at least one set having two different machining quantities exists is included.

"One position" is one position selected on the surface to be processed, and may be arbitrarily selected. "1 position"
May be, for example, any one of the positions where the reference points of the polishing pad are arranged for convenience. That is, in the planarization processing method of the present invention, the processing amount at one position where the reference point of the polishing pad is arranged is reduced to at least one of the other positions where the reference point of the polishing pad is arranged. Embodiments different from the amounts are included.

Therefore, according to the flattening method of the present invention, for example, the thickness of the insulating oxide film formed on the surface of the semiconductor substrate (ie, the distance between the surface of the insulating oxide film and the surface of the semiconductor substrate) ) Is not constant, the thickness of the insulating oxide film can be finally constant by increasing the processing amount of the thicker portion. When a plurality of films are stacked on the substrate, the total thickness of the individual films can be made constant.

The above-mentioned feature regarding the processing amount is realized by a mode in which one dwell time is different from at least one other dwell time in a set of dwell times at each position of the polishing pad. The set of residence time at each position of the polishing pad means that the polishing pad is, for example, at different m locations (m
Are integers greater than or equal to 2) at positions P1 to Pm.
The residence time of the polishing pad at Pm to
When tm is set, it refers to a set having t1 to tm as elements. By making at least one dwell time different from at least one other dwell time in this set, the amount of processing at each position on the surface to be processed is made desired, and thereby the distribution of the amount of processing on the surface to be processed is desired. It can be.

In order to obtain a desired distribution of the processing amount on the surface to be processed, the polishing pads are sequentially arranged in accordance with the positions where the polishing pads are sequentially disposed and the polishing rate at each position on the surface to be processed at that time. It is necessary to determine the dwell time of the polishing pad at the location where it will be performed. In the set of residence times so determined, generally one residence time is different from at least one other residence time. Work surface 1
The processing amount at the position corresponds to the sum of the product of the polishing rate and the residence time of the polishing pad at the one position on the surface to be processed when the polishing pad is disposed at each position.

For example, consider a case where the polishing is performed by arranging the reference point of the polishing pad at the position Pa on the surface to be processed and then moving the polishing pad to another position Pb. Depending on the way of movement (for example, when Pa and Pb are close to each other), the position Za where the surface to be processed overlaps a part of the polishing pad regardless of the position of the polishing pad (the polishing pad is placed on the position Za). Of the work surface)
a is polished twice. Therefore, the position Za of the work surface
Is the product Ma * t of the polishing rate Ma at the position Za of the surface to be processed and the residence time ta at the position Pa of the polishing pad when the polishing pad is disposed at the position Pa.
a, and the sum of the product Mb * tb of the polishing rate Mb at the position Za of the surface to be processed and the residence time tb at the position Pb of the polishing pad when the polishing pad is arranged at the position Pb (Ma * ta + Mb * tb) Becomes In such a case, the respective residence times ta and tb of the polishing pad for making the processing amount at the position Za a desired amount can be obtained by solving a multiple simultaneous equation, as described later, or using a matrix. Is calculated.

As another example, a case where the position Zc of the surface to be processed overlaps only with the polishing pad whose reference point is located at the position Pc on the surface to be processed and does not overlap with the polishing pad located at another position Pd (for example, (When Pc is located far from Pd)
There is. In such a case, the processing amount at the position Zc of the processing surface is a product Mc * tc of the polishing rate Mc at the position Zc of the processing surface and the residence time tc of the polishing pad when the polishing pad is disposed at the position Pa. Desired. Therefore, the processing amount at the position Zc of the surface to be processed can be set to a desired processing amount by appropriately setting the polishing rate Mc and / or the residence time tc of the polishing pad. In the case where a plurality of positions such as the position Pc exist on the surface to be processed, in one embodiment of the flattening method of the present invention, the polishing rate and / or the residence time at one position are different from those at the other at least one position. By doing so, the amount of processing at one position on the surface to be processed is different from the amount of processing at at least one other position, and the surface to be processed can be flattened. In another aspect of the flattening method of the present invention, for example, when the polishing rate is known in advance, when a desired processing amount is set, a residence time to be set is obtained.

The flattening method of the present invention is suitable for polishing a surface of a disk-shaped workpiece using a disk-shaped polishing pad. In that case, the polishing pad
It is preferable to move the work surface in the radial direction. More preferably, by moving the center of the polishing pad radially outward from the center of the surface to be machined, at least two locations where the distance between the center axis of the polishing pad and the center axis of the workpiece is different. It is preferable that the polishing pad is located at the position of. Even more preferably, the centers of the polishing pads are moved radially at equal intervals.

Here, the workpiece and the polishing pad which are "substantially disk-shaped" have not only a workpiece whose surface is perfectly circular but also an orientation flat formed like a semiconductor wafer. In some cases, a circular arc is missing in the part. Furthermore, even if the periphery does not draw a smooth curve, it is assumed to be substantially a disk shape unless the distance from the center is significantly different. For example, a regular polygon having six or more vertices is substantially It may be a workpiece or a polishing pad that is essentially disk-shaped.

Next, a method for determining the residence time of the polishing pad at each position so that the distribution of the processing amount on the surface to be processed is a desired one will be specifically described. The residence time is determined by measuring the polishing rate at each position on the surface to be processed and calculating from the measured polishing rate and the desired processing amount at each position on the surface to be processed. The details will be described below.

First, according to the surface to be processed, the area and type (for example, the material) of the polishing pad, the conditions of swinging of the polishing pad (moving width and frequency at the time of swinging), the number of revolutions of the workpiece, the polishing The pressure between the pad and the workpiece, the type of polishing slurry, polishing conditions such as the number of rotations when rotating the polishing pad, and a plurality of positions on the surface to be processed on which the polishing pad is to be located and at that position The residence time of the polishing pad (ie, polishing time) is appropriately selected. The polishing conditions may be, for example, conditions that are conventionally employed. Next, under the selected conditions, polishing is performed while sequentially changing the position of the polishing pad, and the polishing rate of the surface to be processed is measured.

The reference point of the polishing pad is set to m
When it is located at the positions P1 to Pm, the polishing rate is measured at m different positions Z1 to Zm on the work surface. Positions Z1 to Zm may be the same as or different from P1 to Pm. When the polishing pad is arranged at one position and polished, the polishing rate is measured at m positions Z1 to Zm on the work surface. Therefore, the polishing rate is m
× m will be measured. When the polishing pad is arranged at the position 1 and polished, the positions Z1 to m1 on the surface to be processed are set.
Not all positions in Zm are always polished, and some positions may not be polished. The polishing rate at that position becomes zero. The positions at which the polishing rate is measured are preferably positions P1 to Pm where the polishing pad is located.

The polishing rate is the amount of processing per unit time (usually per minute), and the amount of change in the thickness of the film or the thickness of the workpiece before and after polishing (ie, the amount of processing) is divided by the polishing time. It is required by doing.

The polishing rate of the workpiece surface is determined by extracting one or several workpieces from the same lot set of workpieces to be flattened, and subjecting the workpiece to the polishing conditions selected as described above. Is determined by polishing.

The desired amount of processing at each position on the surface to be processed is determined as follows. First, the thickness of the workpiece is measured at m positions Z1 to Zm where the polishing rate is measured. The thickness of the workpiece may be measured at other locations as well, for example, over the whole. next,
In order to make the surface to be processed flat, the positions Z1 to
It is determined based on the measurement result how much the thickness in Zm should be reduced. The thickness to be reduced at each position corresponds to a desired processing amount. When measuring the polishing rate of the surface to be processed at the positions P1 to Pm where the polishing pad is located as described above, the desired processing amount at the positions P1 to Pm is determined.

The amount of processing at a certain position Z on the surface to be processed is
This corresponds to the total amount of the product of each polishing rate and each residence time of the polishing pad at the position Z when the polishing pad is at each position. That is, when the reference point (for example, the center) of the polishing pad is located at m positions P1 to Pm of the processing surface, the processing amount R at the position Z of the processing surface is represented by the following equation (1):

(Equation 1) Indicated by In the equation (1), Mk is a position P at which the reference point of the polishing pad is the k-th (k is an integer of 1 to m).
The polishing rate at the position Z when the workpiece surface is polished at the position k is shown, and tk indicates the residence time of the polishing pad when the reference point of the polishing pad is at the k-th position Pk. Mk * tk indicates that the reference point of the polishing pad is at the k-th position P
This corresponds to the machining amount at the position Z when it is at k.

In order to determine the residence times t1 to tm of the polishing pad so that the distribution of the processed amount on the surface to be processed becomes a desired one, an equation similar to the equation (1) is used for different m locations on the surface to be processed. It is necessary to create the positions, substitute the desired machining amount at each position into the equation, and solve the m-ary linear simultaneous equations. When the polishing rate is measured at positions Z1 to Zm on the surface to be processed, m pieces of the following formula (2):

(Equation 2) Holds. In the formula (2), Ri indicates the processing amount at the position Zi (i is an integer of 1 to m) of the surface to be processed, and Mik indicates the k-th reference point of the polishing pad (k is 1 to m).
Is a polishing rate at a position Zi (i is an integer of 1 to m) when the surface to be processed is polished while being arranged at a position Pk of any one of the following: The dwell time of the polishing pad when the reference point is at the k-th position Pk is shown. By substituting the desired machining amount at the position Zi (i is an integer of 1 to m) of the surface to be machined into Ri of m equations (2), an m-ary linear simultaneous equation is obtained. . By solving this simultaneous equation, the residence time t1 at the polishing pad positions P1 to Pm is obtained.
To tm is determined.

Such a simultaneous equation includes a matrix M of m rows × m columns using Mik as a component of an i-th row and a k-th column, a matrix X of M rows × 1 column having components of t1 to tm, and R1 to Rm. Can be expressed as R = M × X by a matrix R of m rows × 1 column having Therefore, if the matrix X is unknown, the matrix X
Can be obtained from the product of the inverse matrix M ^{−1 of the} matrix M and the matrix R (R × M ⁻¹ ).

For example, the center of the disk-shaped polishing pad is moved from the center of the disk-shaped workpiece to the outer edge of the workpiece by a distance d in the radial direction of the workpiece n times (n is an integer of 1 or more). In this case, the polishing rate is determined when the polishing pad is positioned at a position where the distance between the center of the polishing pad and the center of the workpiece is xd (x is any integer from 0 to n). Yd (y is any one of 0 to n) from the center of the workpiece
The polishing rate of the surface to be processed at a position separated by (integer) is the component a _ydxd of the (y + 1) _-th row and the (x + 1) _-th column (n +
1) It can be obtained in advance as a matrix A of rows × (n + 1) columns. Here, the position where the pad is arranged and the position where the polishing rate is measured are the same.

The matrix A is represented, for example, as follows:

(Equation 3)

The matrix A indicates the polishing rate at each position when the center axis of the disk-shaped polishing pad is moved by a distance d in the radial direction from the center axis of the disk-shaped workpiece. The row of the matrix A is a polishing rate of the processing surface at a position away from the central axis of the processing object by a predetermined distance, and shows how the polishing rate at the position varies depending on the position of the polishing pad. The columns of the matrix A correspond to the polishing rates at the respective positions on the work surface when the central axis of the polishing pad is at a certain position. In matrix A, the polishing rate is a _ydxd
And the subscript xd (x is an integer, d is the moving distance of the polishing pad per one time) corresponds to the distance between the central axis of the polishing pad and the central axis of the workpiece, and the subscript yd (y is Integer, d
Indicates the position of the surface to be processed, and corresponds to the distance between the center of the workpiece and the position.

For example, a _0d0d indicates the polishing rate at the center of the processing surface when the center axis of the polishing pad overlaps with the center axis of the workpiece, and a _3d2d indicates the polishing axis at the center of the polishing pad. The graph shows the polishing rate of the surface to be processed at a position 3d away from the center of the workpiece when the workpiece is at a position 2d away from the center axis of the workpiece. Polishing is continued until the central axis of the polishing pad passes through the outer edge from the center of the surface to be processed when the central axis of the polishing pad is moved by d. Accordingly, _andnd indicates the polishing rate at the outer edge of the processed surface when the central axis substantially reaches the outer edge of the processed surface. Therefore, the radius of the surface to be processed is r
Assuming _w , r _w = n × d. In the above matrix A, the polishing pad arranged at one certain position simultaneously polishes five positions on the surface to be processed. Polishing rate is 0
At the location represented by, the workpiece is not polished by the polishing pad arranged at that location. The moving distance of the polishing pad represented by d in one time above, that is, the moving distance of the polishing pad when the center axis of the polishing pad moves from one position to the next position is determined by the diameter of the polishing pad and the purpose of the polishing pad. Is appropriately determined according to the processing to be performed.

After the polishing rate at each position of the workpiece under the predetermined conditions is measured in this manner, the residence time of the polishing pad at each position is adjusted in order to set the processing amount at each position to a predetermined amount. To determine. Specifically, if a predetermined processing amount at each position on the surface to be processed is defined as a matrix H and a residence time at each position on the polishing pad is defined as a matrix T, then H =
Since the relationship AT is established, the inverse matrix A ^{-1 of the} above matrix A
And the matrix H, the residence time of the polishing pad at each position can be determined.

That is, the desired amount of processing of the workpiece is determined by calculating the desired amount of processing at a position yd (y is any integer from 0 to n) from the center of the workpiece by the component of the (y + 1) th row. h _yd
Expressed as a matrix H of (n + 1) rows × 1 column; matrix A
From the product of the inverse matrix A ^-1 and the matrix H, the residence time of the polishing pad when the center of the polishing pad is at xd (x is any integer from 0 to n) from the center of the workpiece is The (x
+1) matrix T of (n + 1) rows × 1 column with component t _xd of rows
, The residence time of the polishing pad at each position can be determined.

The matrix H is specifically:

(Equation 4) It is represented by The dwell time of the polishing pad at each position is specifically:

(Equation 5) Indicated by

FIG. 6 shows a state in which the polishing pad is moved from the position where the distance xd between the center of the polishing pad and the center of the work surface is αd (α is an integer of 0 or more) to βd (β is an integer of n or less). 4 is a graph schematically showing an example of a distribution of a polishing amount (that is, a processing amount) in a radial direction from a center 0 to a r of a surface to be processed when the workpiece is moved to a position d. In FIG. 6, the polishing amount is constant at each position from the center 0 to r of the surface to be processed. In FIG. 6, the parts A, B, C, D and E have xd of αd, (α + 1) d, (α + 2) d,
When the polishing pad is arranged at the positions of (β-1) d and βd, the position and the amount of polishing on the workpiece are shown. In FIG. 6, for example, the polishing amount at a position z away from the center 0 of the workpiece is that the distance xd between the center of the polishing pad and the center of the workpiece surface is αd, (α + 1)
When the polishing pad is located at the positions of d and (α + 2) d, it corresponds to the sum of the amounts polished by z. It should be noted that FIG. 6 is only an example.

In the above matrix A, there are cases where all elements other than the diagonal elements are 0. In other words, each of the m different positions Z1 to Zm of the work surface is one polishing pad.
The polishing pad may be polished only when placed at one position, and not polished when the polishing pad is placed at another position. In particular, in such a case, by changing the polishing rate at at least one position on the surface to be processed, the distribution of the amount of processing on the surface to be processed can be made desired.

"Changing the polishing rate at at least one position on the surface to be processed" means that the polishing rate at each position on the surface to be processed is determined in advance under predetermined polishing conditions as described above, and then at least one position is determined. Means changing the polishing rate from the determined polishing rate.

Specifically, the polishing rate at a certain position is changed by changing the number of rotations of the polishing pad at the position when the polishing pad is rotated around its central axis as a rotation axis. The polishing rate increases when the polishing rate is higher than the rotational speed of the polishing pad when the polishing rate is obtained, and decreases when the polishing rate is lower. When the rotation speed of the polishing pad at at least one position is changed, the rotation speed of the polishing pad at the one position generally differs from the rotation speed of the polishing pad at the other at least one position. The polishing rate may be varied by other conventional methods. Polishing rate in at least one position (ie,
When changing the number of revolutions of the polishing pad), the residence time of the polishing pad may be the same at each position, or the residence time of the polishing pad at at least one position may be different from the residence time at the other at least one position. May be.

If the flattening method of the present invention is applied, when the thickness of the workpiece is uniform but the polishing rate of the workpiece is not constant over the entire surface to be processed, the processing amount can be reduced over the entire surface to be processed. It is also possible to perform the flattening process so as to be uniform, that is, to make the distribution of the processed amount of the processed surface uniform.

[0059]

Embodiments of the present invention will be described below. In the flattening method of the present invention, types of the workpiece and the polishing pad are not particularly limited. The present invention
It is particularly preferably applicable to a process of manufacturing a semiconductor device for forming a semiconductor chip. Therefore,
For convenience of description, a specific embodiment of the present invention will be described by taking a planarizing method of a semiconductor device having a substantially disk shape as an example.

FIG. 1 schematically shows a polishing tool used in the present invention in a sectional view in the thickness direction of a workpiece.
In the polishing tool (10) shown in FIG. 1, an elastic member (12) such as an elastic sheet is attached to a polishing pad holder (13), and the polishing pad (11) having a substantially disk shape is an elastic member. (12) It is attached to the polishing pad holder (13) by being placed on it. A space (15) for injecting a fluid is formed in the polishing tool (10) adjacent to the elastic member (12). The polishing pad holder (13) is attached to the rotating head (14). Rotating head (14)
Is connected to a suitable drive means and, as shown, the central axis (100) of the polishing pad (11) which is the vertical axis passing through its center.
And a swing in the horizontal direction.

In the polishing tool (10), the elastic member (12)
Is fixed between the presser ring (16) and the polishing holder (13). In the illustrated embodiment, the screw holes (1
The holding plate (16) is fixed to the polishing holder (13) by screwing a screw (not shown) into 8). Further, a screw (not shown) is screwed into the screw hole (17) to fix the polishing holder (13) to the rotary head (14).

The polishing tool shown in FIG. 1 is used, for example, by being incorporated in a polishing apparatus shown in FIG. In the polishing apparatus shown in FIG. 5, reference numeral 210 denotes a block, 211 denotes a rotary joint, 212 denotes a motor, 213 denotes an air cylinder, 214 denotes a linear guide rail, 215 denotes a slide table, 216 denotes a linear guide rail, and 217 denotes a ball screw. Reference numeral 218 denotes a motor, 219 denotes a rotary joint, 220 denotes a waste liquid receiver, 21 denotes a workpiece, 22 denotes a surface plate, 22a denotes a suction plate, 23 denotes a retainer ring, and 24 denotes a slurry supply unit.

The polishing tool (10) is mounted on the block (210). The polishing tool (10) moves up and down as the block (210) slides on a linear guide rail (214) extending in the vertical direction provided on the slide table (215). The vertical movement of the slide table (215) is controlled by an air cylinder (213). The slide table (215) slides on a guide rail (216) extending in a direction perpendicular to the paper surface. The slide table (215) is connected directly to the ball screw (217).
A reciprocating motion is performed by positioning and speed control by a servomotor (not shown), whereby the polishing tool (10) swings. The polishing tool (10) also has a motor (21
The rotation of 2) rotates around the central axis (100) as the rotation axis.

The workpiece (21) is a suction plate (22a)
It is fixed to the surface plate (22) by being evacuated through. The workpiece (21) can be rotated by rotation of the motor (218).

The workpiece (21) has a slurry supply section (24)
Supplies the slurry. The used slurry is discharged from the waste liquid receiver (220) to the outside of the polishing apparatus.

FIG. 2 shows a part of the steps of the flattening method of the present invention. FIG. 2A shows a state in which the central axis (100) of the polishing pad (11) and the central axis (200) of the workpiece (21) are arranged so as to overlap with each other. The workpiece (21) is rotated about the central axis (100) (200) as a rotation axis, and the polishing pad (11) is swung in the radial direction of the workpiece (21) to change the workpiece surface (21a). This shows a state of polishing. The polishing pad (11) is a polishing tool (1
The workpiece (21) is rotated by the rotation of the workpiece (0), and the workpiece (2)
It rotates by the rotation of the turntable (22) for fixing 1). In the illustrated example, the diameter of the polishing pad (11) is smaller than the diameter of the processing surface (21a), and therefore, the polishing surface (21) with which the polishing pad (11) is not in contact.
a) is exposed. Also, during polishing, the polishing pad (11) is placed in the space (15) in the polishing pad holder (13).
Is pressed against the work surface (21a) by the pressure of the gas injected into the work. A polishing slurry (25) is supplied between the polishing pad (11) and the surface to be processed (21a) from a polishing slurry supply section (24).

FIG. 2B shows that after the polishing step shown in FIG. 2A is completed, the rotational movement of the polishing tool (10) is stopped and the pressure of the gas in the space (15) is released. The state in which the position of the polishing pad (11) is changed by moving the rotation axis (100) of the polishing tool toward the outer peripheral side in the radial direction of the processing surface by the distance d. Also at this position, a part of the processing surface (21a) is exposed from the polishing pad (11).
FIG. 2C shows that the polishing slurry (2) is supplied between the polishing pad (11) and the processing surface (21a) from the polishing slurry supply section (24).
This shows a state in which 5) is supplied and the swing of the polishing tool (10) is started.

FIG. 2D shows a state in which a gas is injected into the space (15) in the polishing pad holder (13), and the polishing pad (11) is pressed against the surface to be processed (21a) by the pressure of the gas. This shows a state in which polishing is performed by rotating the center axis (100) as a rotation axis while swinging (10). In FIGS. 2B to 2D, the workpiece (2
1) is maintained in a state of being rotated about a central axis (200) which is a vertical axis passing through the center.

After the polishing shown in FIG. 2D is completed, the rotation axis of the polishing tool is further shifted in the radial direction to the outer peripheral side of the work surface as shown in FIG.
The position shown in 1) is changed, and the operations shown in FIGS. 2C and 2D are repeated. If the operations shown in FIGS. 2B to 2D are repeated until the rotation center of the polishing tool reaches the outer edge of the surface to be processed, the entire surface to be processed can be processed.

As shown in FIG. 7A, a workpiece (21) is a semiconductor wafer (601) on which wirings (603) are formed and a film (602) made of an insulating material or the like is formed. In general, the period W is several cm and the amplitude t is several tens nm to several μm because the thickness of the film is not constant on the surface to be processed of the wafer.
m undulations occur. The mode of the undulation depends on the material of the film and the like. In the semiconductor device manufacturing process, fine irregularities (604) formed at the time of film formation are eliminated, and this undulation is also eliminated. As shown in FIG.
It is necessary to make the thickness of 2) uniform and completely flatten the surface to be processed.

Therefore, it is necessary to appropriately select the dimensions of the polishing pad (11), the moving distance d per one time of the polishing pad (11), and the like according to the undulation characteristics of the workpiece (21). It is.

For example, in the case of flattening a disk-shaped semiconductor device, for each undulation occurring in the semiconductor device to be processed, the period (the distance between the vertices of the undulations and the adjacent vertices) is measured. Find the shortest cycle among them,
It is preferable to select a disk-shaped polishing pad having a smaller diameter. Alternatively, as shown in FIG. 4, a ring-shaped polishing pad may be used, and the ring width t may be smaller than the shortest period of the undulation.

In the present invention, as shown in FIG. 2B, after polishing at a certain position is completed, the polishing is interrupted and the central axis (100) of the polishing pad (11) is moved by a distance d. For this reason (that is, since the movement of the polishing pad (11) is not continuous), a step is likely to occur between the polishing portion at each position and the polishing portion. In order to eliminate the step, the polishing pad (11) is swung in the radial direction of the workpiece (21) during polishing, as shown in FIG.

As shown in FIG. 2C, the swing of the polishing pad may be started after the polishing pad is moved and before the polishing pad is pressed against the surface to be processed. By swinging in advance before polishing and controlling the width and frequency of the swing, the swing can be reliably performed at a predetermined width and frequency during polishing. However, the timing at which the swing is started is not limited to this, and may be started at the same time that the polishing pad is pressed against the surface to be processed, for example.

As shown in FIGS. 2 (a) and 2 (d), the polishing pad may be rotating (rotating) about its central axis as a rotation axis in addition to swinging. When the polishing pad is rotated, the polishing rate on the surface to be processed increases, so that the flattening process can be performed in a shorter time. However, this rotational movement is arbitrary.

In this manner, the type of polishing pad, the area of the polishing pad, the condition of swinging of the polishing pad, the type of polishing slurry, and the rotational motion of the polishing pad, if necessary, depending on the surface to be processed. After determining the conditions,
The residence time of the polishing pad at each position is determined by appropriately setting the pressure applied between the polishing pad and the surface to be processed, the rotational speed of the workpiece, and the moving distance d of the polishing pad at one time. Specifically, as described above, the residence time at each position is defined as a matrix T, and the polishing rate at each position under predetermined conditions (matrix A) and the predetermined processing amount at each position (matrix H). It is calculated from:

The polishing rate at each position on the work surface is
The area of the polishing pad, the moving distance d per one time of the polishing pad, the pressure between the surface to be processed and the polishing pad, the type of the polishing pad, the condition of the swing of the polishing pad, the number of rotations of the workpiece, and the polishing When the pad rotates, it changes depending on the number of rotations, the type of polishing slurry and whether or not a chemical reaction is involved in polishing, and accordingly, the residence time of the polishing pad at each position on the surface to be processed accordingly. change.

In FIG. 2D, gas is injected into the space (15) in the polishing pad holder (13), and the pressure of the gas is transmitted to the polishing pad via the elastic member (12). The polishing pad (11) is pressed against the work surface (21a) to generate pressure between the work surface (21a) and the polishing pad (11). Gas is preferably used because it is easy to handle and does not contaminate the semiconductor device even if it leaks. The gas is air, N
It may be _second magnitude. Further, instead of gas, another fluid, for example, a liquid may be injected into the polishing pad holder, and in that case, it is desirable to use pure water from the viewpoint of preventing contamination.

When a fluid is injected into the space (15) in the polishing pad holder (13) as in the polishing tool (10) in FIG.
When the polishing pad (11) protrudes from the outer periphery of the processing surface (21a), the protruding portion loses the support by the processing surface (21a), and the protruding portion hangs down and the outer peripheral portion of the processing surface (21a). Apply large pressure to the vicinity. As a result, excessive polishing is likely to occur near the outer peripheral portion of the work surface (21a). As an example of a means for preventing this excessive polishing, as shown in FIG. 2, a retainer ring (23) is attached to a workpiece (2).
There is a method of providing it on the outer circumference of 1). Retaining ring (23)
Supports the polishing pad (11) even when the top surface is substantially in the same plane as the processing surface (21a) and a part of the polishing pad (11) protrudes from the processing surface (21a); Excessive polishing near the outer periphery of the work surface (21a) is prevented. It is preferable that the retainer ring (23) can support the entire protruding portion, no matter how the polishing pad (11) protrudes. Therefore, it is preferable that the top surface of the retainer ring (23) has an area large enough to support the entire protruding portion even when the protruding portion of the polishing pad (11) is maximized.

Further, in order to prevent excessive polishing near the outer peripheral portion of the surface to be processed (21a), as shown in FIG.
May be used. According to the polishing tool (30), a fluid (for example, gas) is sent into the bubbles of the foam (36), and the pressure of the fluid is transmitted to the polishing pad via the foam (36) and the elastic member (32). This allows the polishing pad (31) to be pressed against the work surface (21a).

Since the foam (36) has a constant shape, partial expansion is unlikely to occur in the foam (36).
Therefore, the polishing pad (31) is located at the outer peripheral portion of the processing surface (21a), and a part of the polishing pad (31) is
Even in the case of protruding from the outer periphery of a), the pressure applied to the polishing pad (31) in the protruding portion does not become significantly larger than in other portions. Therefore, the dimension of the retainer ring (23) for supporting the protruding part can be made small as long as it can support a part of the protruding part,
According to the polishing tool of FIG. 3, the retainer ring (23) can be made smaller than when the polishing tool of FIG. 1 is used. The foam (36) is preferably, for example, urethane foam. As shown in FIG. 3, the polishing pad holder (3
3) may be attached to a rotating head (34) as needed, so that the polishing pad (31) can rotate around the central axis (300) as a rotating axis.

The flattening method according to the present invention is, specifically,
After wiring is formed on one surface of a semiconductor wafer having a diameter of 150 to 300 mm with aluminum, P-TEOS, O ₃ -N
A workpiece on which an insulating oxide film having a thickness of about 1300 nm made of SG, BPSG, or the like is formed is used as a workpiece, and can be implemented to planarize the insulating oxide film. In such a workpiece, usually, the thickness of the insulating oxide film is not constant,
Undulation with a period of 50 to 200 mm and an amplitude of 50 to 200 nm exists on the surface to be processed.

The flattening process is performed by polishing the surface to be processed while supplying a polishing slurry using a polishing pad selected according to the type of the film to be processed. When polishing the insulating oxide film, a polishing pad made of polyurethane foam is preferably used.

The polishing pad preferably has a diameter smaller than the shortest cycle of the undulation cycles formed on the surface to be processed. Therefore, the diameter of the polishing pad is preferably 50 to 200 mm.

When a polishing tool as shown in FIG. 1 is used, the elastic member is preferably a circular sheet of neoprene rubber having a thickness of 0.5 to 4 mm. The elastic sheet is attached to the polishing pad holder so as to form a space for accommodating a fluid in the polishing tool together with the polishing pad holder. The elastic sheet is attached to the polishing pad holder by, for example, sandwiching and fixing the elastic sheet between the press ring and the polishing pad holder. The polishing pad is attached to the surface of the elastic member with, for example, a double-sided tape coated with a silicone-based adhesive.

In the case where the above-mentioned workpiece is polished by the method shown in FIG. 2 using the above-mentioned polishing tool, preferable polishing conditions will be described below.

The rotation speed of the polishing pad is 20 to 180 rpm,
It is preferable that the rotation speed of the workpiece is 60 to 360 rpm. The polishing pad has a swing width (a position between the center of the polishing pad when the polishing pad is at the leftmost position and the center of the polishing pad when the polishing pad is at the rightmost position during the swinging in FIG. 2A). Distance between 10 to 50 mm and 10 to 60
It is preferable to swing at a frequency of times / minute.

The fluid supplied into the polishing tool is preferably
It is compressed air. It is preferable that a pressure of 5 to 50 kPa is generated between the polishing surface of the polishing pad and the processing surface of the workpiece by supplying the fluid into the polishing tool.

When polishing an insulating oxide film containing Si and O, a polishing slurry in which silica fine particles or ceria fine particles are dispersed in an NH ₄ OH aqueous solution or a KOH aqueous solution is preferably used as abrasive grains. Polishing slurry is 50 ~
Preferably, it is supplied at 200 ml / min.

The moving distance d per one time of the polishing pad is:
Generally, it is preferable that the radius is 1/5 to 1/20 of the radius of the workpiece. Therefore, as for the above-mentioned workpiece, it is preferable that the moving distance d per one time of the polishing pad is 5 to 20 mm. When the workpiece is polished under the above polishing conditions, the polishing rate is generally 50 to 300 nm / min. The workpiece is polished so that the processing amount (removal amount) of the insulating oxide film is, for example, 1000 nm. Therefore, the time that the polishing pad stays at each position is 30 to 180.
Seconds.

[0091] The retainer ring is preferably dimensioned to support a portion protruding from the work surface when the central axis of the polishing pad reaches the outer edge of the work. Therefore, the width of the retainer ring (the difference between the outer diameter and the inner diameter) is set to be equal to or larger than the radius of the polishing pad.

When a polishing tool as shown in FIG. 3 is used, a foam having open cells is arranged in a space formed between the elastic member and the polishing holder. The foam is preferably a urethane foam (ie, a urethane sponge). The foam is formed into the shape of the space in the polishing tool. For example, the foam may have one surface fixed to the polishing tool with a double-sided tape and the other surface fixed to the elastic member with a double-sided tape. Since the open-cell foam is in communication between the cells, it can be expanded by supplying fluid from one location. Preferably, the fluid is supplied from a plurality of locations.

In the method of the present invention, as described in the section of the prior art, in the step of manufacturing a semiconductor device, wiring is formed on a semiconductor wafer with an appropriate conductive material, and a film made of an insulating material is formed thereon. It is suitable for a step of polishing an insulating material after lamination. Further, the present invention is implemented to form a groove in a semiconductor wafer, form a film of a conductive material so as to fill the groove with a conductive material, and then remove the conductive material other than the groove. You may apply to a grinding | polishing process. Further, the present invention may be applied to a semiconductor manufacturing process other than these, for example, a process of polishing and flattening a polysilicon film, an epitaxial film, a resist film, a metal plug, or a silicon nitride film formed on a semiconductor wafer.

The flattening method of the present invention can also be applied to a liquid crystal display panel manufacturing process. In the manufacturing process of the liquid crystal display panel, the flattening method of the present invention is performed to flatten the conductor film and / or the insulating film formed on the substrate of the liquid crystal display panel.

[0095]

According to the flattening method of the present invention, the polishing pad is positioned at at least two different positions on the processing surface so that a part of the processing surface is exposed from the polishing pad. By bringing the polishing pad into contact with the polishing pad to generate a pressure therebetween, the polishing pad is swung, and the workpiece is rotated around its central axis as a rotation axis to polish the workpiece surface, whereby the workpiece surface is polished. The processing amount at each position is set to a desired amount.

In a preferred embodiment of the flattening method according to the present invention, in the set of dwell times at each position of the polishing pad, one dwell time is made different from at least one other dwell time. The processing amount at each position on the surface is a desired amount. In another aspect of the flattening method of the present invention, the polishing pad is rotated around its central axis as a rotation axis, and the rotation speed of the polishing pad at one position is the same as the rotation speed of the polishing pad at at least one other position. By making them different, the processing amount at each position on the processing surface becomes a desired amount.

Therefore, according to this flattening method, the processed surface can be uniformly flattened regardless of the type of the processed surface. Further, according to the present invention, the residence time at each position of the polishing pad or the number of rotations of the polishing pad is set in accordance with the characteristics of the surface to be processed. Can be implemented.

Further, by using a polishing tool including a foam having open cells, even if a part of the polishing pad protrudes from the surface to be processed and loses its support, the polishing pad may protrude through the foam to the protruding portion of the polishing pad. The pressure applied is not excessively greater than the pressure applied to the other parts. Therefore, according to the flattening device including such a polishing tool, the flattening method of the present invention, in which the polishing pad is often exposed (protrudes) from the surface to be processed due to the movement of the center axis of the polishing pad, is performed. It is convenient for

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of an example of a polishing tool for performing a flattening method according to the present invention.

FIGS. 2A to 2D are schematic cross-sectional views illustrating steps of a planarization method according to the present invention.

FIG. 3 is a schematic cross-sectional view of an example of a polishing tool included in the flattening device of the present invention.

FIG. 4 is a schematic plan view of an example of a polishing pad for performing the flattening method of the present invention.

FIG. 5 is a schematic cross-sectional view of an example of a polishing apparatus for performing the planarization processing method of the present invention.

FIG. 6 is a graph schematically showing a polishing amount distribution when the flattening method of the present invention is performed.

FIG. 7A is a schematic cross-sectional view of a semiconductor device before flattening, and FIG. 7B is a schematic cross-sectional view of the semiconductor device after flattening.

FIG. 8 is a schematic sectional view showing a conventional flattening method.

[Explanation of symbols]

10, 30 ... polishing tool, 1, 11, 31 ... polishing pad, 2, 12, 32 ... elastic body, 3, 13, 33 ... polishing pad holder, 14, 34 ... Rotating head, 15 ... space, 100 ... center axis of polishing pad, 200 ... center axis of workpiece, 300 ... center axis of polishing pad, 5, 21 ...
Workpiece, 5a, 21a ... Workpiece surface, 6, 22 ... Rotary table, 23 ... Retainer, 24 ... Polishing slurry supply unit, 25 ... Polishing slurry, 36 ... Foaming Body, 210 ...
Block, 211 ... Rotary joint, 212 ...
Motor, 213 ... Air cylinder, 214 ... Linear guide rail, 215 ... Slide table, 216 ... Linear guide rail, 217 ... Ball screw, 218 ... Motor, 219 ... .Rotary joint, 220 ... waste liquid receiver, 22a ... suction plate.

Claims (15)

[Claims] 1. A flattening method for polishing and flattening a work surface of a work with a polishing pad, wherein at least two different positions on the work surface are: (B) contacting the surface to be processed with the polishing pad to generate a pressure therebetween, and (c) polishing. While the pad is rocked, the workpiece is rotated around the center axis of the workpiece and the workpiece surface is polished, and the processing amount at one position on the workpiece surface is at least one other. A flattening processing method different from the processing amount at the position. 2. The flattening method according to claim 1, wherein one dwell time is different from at least one other dwell time in a set of dwell times at respective positions of the polishing pad. 3. The flattening method according to claim 1, wherein an area of a polishing surface of the polishing pad is smaller than an area of a processing surface of the workpiece. 4. The method according to claim 1, wherein the workpiece and the polishing pad are disk-shaped, and the polishing pad is swung in a radial direction of the workpiece. 5. The method according to claim 5, wherein the center of the polishing pad is moved radially outward from the center of the surface to be processed, so that the distance between the central axis of the polishing pad and the central axis of the workpiece is different. The polishing pad is positioned at a position of the polishing pad such that a surface to be processed is exposed from the polishing pad.
4. The flattening method according to 1. 6. The disk-shaped polishing pad is moved from the center of the disk-shaped workpiece to the outer edge of the workpiece in the radial direction of the disk at a distance d by n times (n is an integer of 1 or more). When the polishing pad is located at a position where the distance between the center of the polishing pad and the center of the workpiece is xd (x is an integer of any one of 0 to n), The polishing rate of the surface to be processed at a position yd away from the center of the target is (y + 1) _-th row and (x + 1) _-th column component a _ydxd (n +
1) It is obtained in advance as a matrix A of rows × (n + 1) columns; a desired machining amount of the workpiece is yd (y is 0) from the center of the workpiece.
The inverse matrix A ^-1 of the matrix A; the desired processing amount at the position of any one of an integer) of ~n the (y + 1) row and the component h _yd of (n + 1) expressed as a matrix H of row × 1 column From the product of the matrix H, the center of the polishing pad is xd (x
(N is an integer of any one of 0 to n), and the residence time of the polishing pad at the position of (x + 1) -th row component t _xd is determined by calculating a matrix T of (n + 1) -row × 1 column. The flattening method according to claim 5, wherein the residence time of the polishing pad at the position is determined. 7. The flattening method according to claim 1, wherein the polishing pad is swung, and the polishing pad is rotated about a center axis thereof. 8. The method according to claim 7, wherein the rotational speed of the polishing pad at one position is different from the rotational speed at at least one other position. 9. The flattening method according to claim 1, wherein swinging of the polishing pad is started before pressure is generated between the surface to be processed and the polishing pad. 10. A fluid is sent into a space in the polishing tool, in which the polishing pad is in contact with the other surface of the elastic member disposed on one surface, and the pressure of the fluid is reduced by the elastic member. The flatness according to any one of claims 1 to 9, wherein pressure is applied to the surface to be processed from the polishing pad side to generate pressure between the surface to be processed and the polishing pad by transmitting the pressure to the polishing pad via the polishing pad. Processing method. 11. A fluid is sent into a foam having open cells arranged in contact with the polishing pad via an elastic member in the polishing tool, and a pressure of the fluid is applied to the polishing pad via the foam and the elastic member. 11. The method according to claim 1, wherein the pressure is applied to the work surface from the polishing pad side by transmitting the pressure to generate a pressure between the work surface and the polishing pad. 12.
The flattening method described in the paragraph. 12. The method according to claim 10, wherein the fluid is a gas or a liquid. 13. The flattening method according to claim 1, wherein the method is performed for performing a chemical mechanical polishing process or a mechanochemical polishing process. 14. The flattening method according to claim 1, which is performed in a semiconductor device manufacturing process. 15. A polishing pad, a polishing pad holder, a foam having open cells disposed in the polishing pad holder,
And a polishing tool including a polishing tool comprising an elastic member interposed between the polishing pad and the foam.