JP2009094096A - Semiconductor device manufacturing apparatus and semiconductor device manufacturing method - Google Patents

Abstract

A semiconductor device manufacturing apparatus and a semiconductor device manufacturing method capable of stabilizing a polishing rate and polishing rate uniformity of a film to be polished on a semiconductor wafer and reducing variations in the semiconductor device.
An abrasive holding plate 107 made of a disk-like plate material having a large number of diamond abrasive grains 120 fixed on one surface, and a base metal 108 having a concave portion 108b into which the abrasive holding plate 107 is fitted on one surface. A two-body conditioner 104 composed of The depth 111 of the recess 108b is smaller than the thickness 110 of the abrasive grain holding plate 107, and the abrasive grain holding plate 107 is fixed to the base metal 108 in a state of being fitted into the concave part 108b of the base metal 108. In this configuration, the protruding amount 109 from the base metal of the abrasive grain holding plate 107 in the conditioner 104 is set in the range of 140 μm to 200 μm.
[Selection] Figure 2

Description

  The present invention relates to a semiconductor device manufacturing apparatus and a semiconductor device manufacturing method, and more particularly to a semiconductor device manufacturing apparatus and a semiconductor device manufacturing method applied to a planarization step in a semiconductor device manufacturing process.

  In a semiconductor device manufacturing process, chemical mechanical polishing (hereinafter abbreviated as CMP) is used as a method for planarizing a thin film formed on the surface of a silicon wafer. In recent years, the CMP process is frequently used in a method of forming a copper wiring of a semiconductor device. FIG. 6 is a diagram illustrating a CMP process in forming a copper wiring. When forming the copper wiring, first, as shown in FIG. 6A, tantalum nitride (TaN) for preventing the Cu film 203 from peeling on the interlayer insulating film 201 in which the recesses 204 such as vias and trenches are formed in advance. A lower layer film 202 in which a barrier metal such as a tantalum (Ta) film that prevents diffusion of Cu into the insulating film and an adhesion layer such as a film are sequentially deposited is deposited by a sputtering method or the like. Next, a Cu film 203 is deposited on the lower layer film 202 by plating or the like. Thereafter, as shown in FIG. 6B, the copper wiring is completed by removing the unnecessary Cu film 203 outside the recess 204 by CMP processing.

  2. Description of the Related Art A semiconductor device manufacturing apparatus (hereinafter, referred to as a CMP apparatus) that performs a CMP process includes a CMP unit that performs a CMP process on a thin film on the surface of a semiconductor wafer, a cleaning unit that cleans the CMP-processed semiconductor wafer, and a wafer transfer And a transport system. FIG. 7 is a schematic perspective view showing a main configuration of a CMP unit in a conventional CMP apparatus. As shown in FIG. 7, the platen 21 is configured to be rotatable around the central axis by a motor or the like. A polishing pad 221 having a concavo-convex pattern is disposed on the platen 21. The polishing pad 221 is made of, for example, a foamed urethane material that is a porous material and has numerous irregularities on the surface thereof.

  Opposite to the polishing pad 221, a polishing head 223 that holds the semiconductor wafer 102 on which the film to be polished is formed is disposed so as to be movable up and down. The polishing head 223 is configured to be rotatable in a plane parallel to the surface of the polishing pad 221 around the polishing head rotating shaft 222. A slurry supply mechanism 224 that supplies the polishing slurry 225 to the polishing pad 221 is disposed on the polishing pad 221. By supplying the slurry 225 from the slurry supply mechanism 224 to the platen 21 rotating at a predetermined rotational speed, and pressing the polishing head 223 holding the semiconductor wafer 102 against the polishing pad 221 with a predetermined load and rotational speed, The film to be polished on the semiconductor wafer 102 is polished.

  As the polishing progresses, the unevenness on the surface of the polishing pad 221 is buried with the slurry 225 and polishing scraps, the surface unevenness of the polishing pad 221 itself is smoothed, and the polishing rate of the polishing process gradually decreases.

  In order to avoid this decrease in the polishing rate, the polishing pad 221 is conditioned. The conditioner 233 faces the polishing pad 221 and is configured to be movable up and down and rotatable in a plane parallel to the surface of the polishing pad 221 around the conditioner rotation shaft 232. Conditioning is performed by pressing abrasive grains made of diamond or the like provided on the surface of the conditioner 233 against the polishing pad 221 while the conditioner 233 is rotated. Conditioning may be performed independently of the polishing of the semiconductor wafer 102 or may be performed independently of the polishing of the semiconductor wafer. In any case, due to the conditioning of the polishing pad 221, the surface of the polishing pad 221 having a reduced polishing rate is cut by contact with the conditioner 233, and the polishing rate increases.

  However, in an actual CMP apparatus, even when conditioning is performed, the polishing rate of the film to be polished on the semiconductor wafer 102 and the uniformity of the polishing rate vary as the usage time of the polishing pad 221 and the conditioner 233 increases. Occurs. Such fluctuations in the polishing rate and polishing rate uniformity of the film to be polished cause variations in the characteristics of the semiconductor device, which is a problem in manufacturing the semiconductor device.

In response to this problem, Patent Document 1 described later discloses a film to be polished on a semiconductor wafer by controlling the pressing load of a conditioner for conditioning a polishing pad and the grain size of diamond abrasive grains fixed on the conditioner surface. A technique for suppressing a decrease in the polishing rate is disclosed.
JP 2002-299289 A

  However, even when the technique disclosed in Patent Document 1 is applied, there is a problem that the polishing rate is lowered and the uniformity of the polishing rate is deteriorated, and the characteristic variation of the semiconductor device is increased. As a result of analyzing the phenomenon, the inventors of the present application have found that the cutting rate of the polishing pad during conditioning is greatly reduced as the use time of the conditioner increases. That is, since the cutting rate of the polishing pad during conditioning varies greatly, even when the technique disclosed in Patent Document 1 is applied, the polishing rate of the film to be polished and the uniformity of the polishing rate are sufficiently deteriorated. It cannot be suppressed. Also, it is very difficult to change the grain size of the diamond abrasive grains fixed to the pressing load or the conditioner surface in response to such fluctuations in the pad cutting rate.

  The present invention has been proposed in view of the above-described conventional problems, paying attention to the shape of the conditioner, stabilizing the polishing rate and polishing rate uniformity of the film to be polished on the semiconductor wafer, and varying semiconductor devices. An object of the present invention is to provide a semiconductor device manufacturing apparatus and a semiconductor device manufacturing method capable of reducing the above.

  In order to solve the above problems, the present invention employs the following technical means. First, the present invention presupposes a semiconductor device manufacturing apparatus that polishes a polishing target surface by relatively moving the semiconductor substrate and the polishing pad in a state where the polishing target surface of the semiconductor substrate is pressed against the polishing pad. Yes. In the semiconductor device manufacturing apparatus according to the present invention, a conditioner that contacts the polishing pad and conditions the polishing pad includes a plate on which diamond abrasive grains are fixed, and a base metal on which the plate is fixed. With. The protruding amount of the plate surface from the base metal is 140 μm or more and 200 μm or less.

  According to this configuration, the activity of the diamond abrasive grains against the polishing pad can be maintained, and the pad cutting rate at the same pressing pressure can be stabilized. As a result, the polishing rate uniformity in the film to be polished can be improved, and variations in characteristics of the semiconductor device can be sufficiently suppressed.

  In another aspect, the present invention relates to a semiconductor device that polishes the polishing target surface by relatively moving the semiconductor substrate and the polishing pad in a state where the polishing target surface of the semiconductor substrate is pressed against the polishing pad. A manufacturing method can also be provided. That is, in the method for manufacturing a semiconductor device according to the present invention, first, a conditioner in which the surface of a plate to which diamond abrasive grains are fixed protrudes in a range of 140 μm to 200 μm from a base metal to which the plate is fixed is provided. The polishing pad is conditioned by contacting the polishing pad. Then, the surface to be polished is polished by the conditioned polishing pad.

  ADVANTAGE OF THE INVENTION According to this invention, a diamond abrasive grain can be pressed to a polishing pad more efficiently than before, and cutting of a polishing pad and discharge | emission of polishing waste can be performed efficiently. For this reason, the change of the pad cutting rate can be reduced, and the polishing rate can be maintained without changing the pressing load or the particle diameter of the diamond abrasive grains fixed to the conditioner surface. Therefore, the polishing rate and uniformity of the film to be polished on the semiconductor wafer can be stabilized. As a result, it is possible to prevent overpolishing and insufficient polishing of the film to be polished, and to improve the manufacturing yield and reliability of the semiconductor device. As a result, the conditioner life can be extended, and the manufacturing cost of the semiconductor device can be suppressed.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following embodiments, the present invention is described as a CMP apparatus for polishing a polishing target surface by relatively moving the semiconductor substrate and the polishing pad in a state where the polishing target surface of the semiconductor substrate is pressed against the polishing pad. It is materialized.

(First embodiment)
FIG. 1 is a schematic perspective view showing a main configuration of a CMP unit included in the CMP apparatus according to the first embodiment of the present invention. The semiconductor device manufacturing apparatus of this embodiment includes a cleaning unit that cleans a semiconductor wafer that has been subjected to a CMP process in a CMP unit, and a transport system that transports the wafer in the device, as in the conventional apparatus. However, since it is not directly related to the present invention, description thereof is omitted here.

  As shown in FIG. 1, the CMP unit includes a disk-shaped platen 100 configured to be rotatable around a central axis by a motor or the like. On the platen 100, a polishing pad 101 made of, for example, a urethane foam material is disposed which is a porous material and has numerous irregularities on the surface thereof. Above the polishing pad 101, a polishing head 103, a slurry supply mechanism 105, and a conditioner 104 are arranged.

  The polishing head 103 holds the semiconductor wafer 102 by suction while facing the platen 100. The polishing head 103 is configured to be movable up and down with respect to the polishing pad 101, and is configured to rotate around the central axis in a plane parallel to the surface of the polishing pad 101. The conditioner 104 includes a mechanism for moving the conditioner 104 up and down relative to the polishing pad 101, a mechanism for rotating the conditioner 104 around the central axis in a plane parallel to the surface of the polishing pad 101, and the surface of the polishing pad 101. The conditioner 104 is supported by a conditioner holder 106 having a mechanism for moving the conditioner 104 horizontally (hereinafter referred to as a sweep) within a parallel plane. The slurry supply mechanism 105 supplies the slurry onto the polishing pad 101.

  By supplying the slurry from the slurry supply mechanism 105 to the platen 100 rotating at a predetermined rotational speed, and pressing the polishing head 103 holding the semiconductor wafer 102 against the polishing pad 101 with a predetermined load and rotational speed, The film to be polished on the semiconductor wafer 102 is polished. In the present embodiment, the conditioner holder 106 presses the conditioner 104 against the polishing pad 101 with a predetermined load and rotation speed while polishing the film to be polished on the semiconductor wafer 102, and the conditioning (shaping) of the polishing pad 101 is polished. In parallel.

  FIG. 2 is a cross-sectional view showing the structure of the conditioner 104 of this embodiment. As shown in FIG. 2, the conditioner 104 according to the present embodiment includes an abrasive grain holding plate 107 to which a large number of diamond abrasive grains 120 are fixed, and a base metal 108 to which the abrasive grain holding plate 107 is fixed. The abrasive grain holding plate 107 is made of a disk-shaped plate material having diamond abrasive grains 120 fixed on one surface. The base metal 108 is provided with a recess 108 b into which the abrasive grain holding plate 107 is fitted on one surface, and the other surface is held by the conditioner holder 106. Note that the depth 111 of the recess 108 b is smaller than the thickness 110 of the abrasive grain holding plate 107.

  The abrasive grain holding plate 107 is fixed to the base metal 108 in a state in which the abrasive grain holding plate 107 is fitted into the recess 108 b of the base metal 108. In this case, the diamond abrasive grain holding surface 107a of the abrasive grain holding plate 107 protrudes from the one surface 108a of the base metal 108 on which the recess 108b is formed with a protruding amount 109. In the present embodiment, the protruding amount 109 is set to 140 μm or more and 200 μm or less as compared with the conventional case where the protrusion amount is about 70 μm. The flatness of the abrasive grain holding plate 107 is 0.05 mm or less in the plane of the abrasive grain holding plate 107, and the degree of parallelism (abrasiveness of the abrasive grain holding plate 107 when supported by the conditioner holder 106. The position of the other end in the direction perpendicular to the polishing pad 101 with respect to one end of the grain holding plate 107 is 0.07 mm or less. The diamond abrasive grains 120 have an average particle diameter of 100 μm and are held in a state where a part thereof is buried in the abrasive grain holding plate 107.

  For example, when the film to be polished on the semiconductor wafer 102 is an interlayer insulating film made of a silicon oxide film in the copper wiring forming process, the slurry is supplied onto the polishing pad 101 at a flow rate of about 100 to 500 ml / min. In this case, silica can be selected as the abrasive contained in the slurry. The pressure for pressing the polishing head 103 holding the semiconductor wafer 102 against the polishing pad 101 can be 1 to 10 psi (6.89 to 68.9 kPa). Generally, there is a correlation between the polishing rate and the pressing pressure of the polishing head 103, and the set pressure is appropriately changed depending on the process (polishing thickness, slurry type, etc.) and device structure (wiring density, basic polishing film type, etc.). Further, both the polishing head 103 and the platen 100 rotate at about 10 to 100 rpm, and both rotate in the same direction. When this rotational speed is high, the polishing rate tends to increase, but the polishing characteristics change because the amount of slurry wrapping between the semiconductor wafer 102 and the polishing pad 101 changes. For this reason, the set pressure of the rotational speed of the polishing head 103 and the rotational speed of the platen 100 is appropriately changed depending on the process and the device structure. The pressure for pressing the conditioner 104 against the polishing pad 101 can be 1 to 10 psi (6.89 to 68.9 kPa). In this case, the conditioner 104 is rotated at a rotation speed of about 100 rpm. Further, the conditioner 104 is swept over the entire radial direction of the polishing pad 101 so as to contact the entire surface of the polishing pad 101.

  According to this embodiment, when the polishing pad 101 is conditioned by the value of the protrusion amount 109 from the base metal 108, the amount of sinking of the conditioner 104 into the polishing pad 101 and the contact state are in an optimal state, and during polishing, At all times, the activity of the diamond abrasive grains 120 with respect to the polishing pad 101 can be maintained. That is, it is possible to suppress a decrease in the polishing rate due to clogging of the polishing pad 101 during the polishing process.

  FIG. 3 is a diagram showing the relationship between the pad cutting rate and the conditioner usage time. Here, the pad cutting rate is a speed (μm / hour) at which the polishing pad 101 is cut by the conditioner 104. The conditioner use time is the total time for which the polishing pad 101 is actually conditioned. In FIG. 3, the horizontal axis corresponds to the conditioner usage time, and the vertical axis corresponds to the pad cutting rate. In FIG. 3, IC 1000 manufactured by Nitta Haas is used as the polishing pad 101. The rotation speed of the platen 100 is 100 rpm, and the pressing pressure of the conditioner 104 is 10 psi (68.9 kPa). Further, slurry containing silica as abrasive grains is supplied to the surface of the polishing pad 101 at a flow rate of 200 ml / min.

  As can be seen from the broken line in FIG. 3, in the conventional conditioner having the protrusion amount of about 70 μm shown in FIG. 2, it can be understood that the pad cutting rate rapidly decreases as the conditioner usage time increases. For this reason, with the conventional protrusion amount, the conditioning of the polishing pad 101 becomes insufficient as the conditioner usage time increases, and clogging of the polishing pad 101 due to polishing dust or the like is not eliminated during polishing of the semiconductor wafer 102, The polishing rate decreases rapidly. Further, such a decrease in the polishing rate occurs non-uniformly on the polishing pad 101, whereby the film to be polished on the semiconductor wafer 102 is non-uniformly polished.

  On the other hand, as shown by the solid line in FIG. 3, when the conditioner 104 of this embodiment is used, the conditioner usage time in which the pad cutting rate is reduced to about 40% at the start of use (arrows in FIG. 3). Even when it reaches part A), it can be understood that the pad cutting rate is maintained at about 70% of that at the start of use. That is, in the present embodiment, a decrease in the pad cutting rate accompanying an increase in the conditioner use time can be significantly suppressed as compared with the conventional case, and the polishing rate of the film to be polished is reduced and the polishing rate is not uniform in the semiconductor wafer surface. Can be suppressed. The reason why the reduction of the pad cutting rate can be suppressed by the configuration of the present embodiment is that the diamond abrasive grains can be more efficiently pressed onto the polishing pad than before, and the cutting debris and polishing debris of the polishing pad are in a condition. This is presumably because it can be efficiently carried out between the na 104 and the polishing pad 101.

  FIG. 4 shows a normalized polishing rate with respect to the conditioner usage time and polishing with respect to the conditioner usage time when the film to be polished on the semiconductor wafer is an interlayer insulating film made of a silicon oxide film in the copper wiring formation process. It is a figure which shows the in-plane uniformity of a rate. In FIG. 4A, the horizontal axis corresponds to the conditioner usage time, and the vertical axis corresponds to the polishing rate normalized by the polishing rate at the start of use. In FIG. 4B, the horizontal axis corresponds to the conditioner usage time, and the vertical axis corresponds to the in-plane uniformity of the polishing rate. Similar to FIG. 3, the rotation speed of the platen 100 is 100 rpm, and the pressing pressure of the conditioner 104 is 10 psi. The slurry flow rate is 200 ml / min.

  As shown by a broken line in FIG. 4A, when the conventional conditioner having a protrusion amount of about 70 μm shown in FIG. 2 is used, the polishing rate is rapidly decreased as the conditioner usage time increases. Understandable. On the other hand, even when the conditioner usage time (arrowed portion B in FIG. 4 (a)) where the polishing rate is reduced to about 14% from the start of use is reached in the past, the condition of the present embodiment. When the na 104 is used, it can be understood that the decrease in the polishing rate is suppressed to about 5% at the start of use, as indicated by the solid line in FIG.

  Further, as shown by a broken line in FIG. 4B, it can be understood that when the conventional conditioner is used, the polishing rate uniformity is rapidly deteriorated as the conditioner usage time increases. On the other hand, even in the case where the polishing rate uniformity has reached the conditioner usage time (arrow C in FIG. 4B) where the polishing rate uniformity has deteriorated to about 4 times from the start of use, this embodiment When the conditioner 104 is used, it can be understood that the deterioration of the polishing rate uniformity is suppressed to 2 times or less as shown by the solid line in FIG. Therefore, according to the present embodiment, variation in the polishing amount of the film to be polished can be reduced without changing the pressing load or the particle size of the diamond abrasive grains fixed to the conditioner surface, and the characteristics of the semiconductor device Variations can be reduced. As a result, the manufacturing yield and reliability of the semiconductor device can be improved. In addition, since the reduction of the pad cutting rate is moderate as compared with the conventional case, as a result, the conditioner life can be extended and the manufacturing cost of the semiconductor device can be suppressed.

  In order to obtain the above effects, it has been confirmed that the protruding amount 109 is 140 μm or more, and it is confirmed by logic calculation that 200 μm or less is desirable.

(Second Embodiment)
As described in the first embodiment, a semiconductor device is manufactured using a CMP apparatus using the two-body conditioner 104 having the structure described in FIG. The deterioration of the in-plane uniformity can be suppressed, and the manufacturing yield and reliability of the semiconductor device can be improved. FIG. 5 is a flowchart showing a manufacturing process of a semiconductor device in a CMP apparatus including the conditioner 104 having the above-described structure.

  As shown in FIG. 5, in the method of manufacturing a semiconductor device according to the present embodiment, the conditioner 104 having the structure shown in FIG. 2 is first mounted on the CMP unit (step S501). In the case where the conditioner 104 is already mounted in the CMP unit, in this step, for example, before the polishing of the semiconductor wafer 102 in the CMP unit is started, the conditioner 104 is used using a three-dimensional microscope or the like. It is confirmed whether or not the configuration shown in FIG. That is, it is determined whether or not the protruding amount of the abrasive grain holding plate 108 is in the range of 140 μm or more and 200 μm or less. If it is not in the range of 140 μm or more and 200 μm or less, the conditioner 104 having the protruding amount 109 is used. Exchanged.

  Next, the polishing pad 101 is conditioned using the conditioner (step S502). Then, the semiconductor wafer to be polished is carried into the CMP unit, and the surface of the semiconductor wafer is polished by the polishing pad 101 that is appropriately sharpened by the conditioning (steps S503 and S504). For example, when the surface of the semiconductor wafer 102 has the structure shown in FIG. 6, the copper film 203 and the lower layer film 202 are polished and removed in this step. As described in the first embodiment, the conditioning of the polishing pad 101 and the polishing of the semiconductor wafer may be performed in parallel.

  The semiconductor wafer that has been polished is carried into a cleaning section, where cleaning and drying are performed (step S505). The semiconductor wafer that has been cleaned and dried is advanced to the next process (step S506).

  Each of the above steps can be performed using the semiconductor device manufacturing apparatus described in the first embodiment.

  According to the present embodiment, the variation in the polishing amount of the film to be polished can be reduced without changing the pressing load or the particle size of the diamond abrasive grains fixed to the conditioner surface, and the variation in characteristics of the semiconductor device can be reduced. Can be reduced. As a result, the manufacturing yield and reliability of the semiconductor device can be improved.

  As described above, according to the present invention, it is possible to press the diamond abrasive grains to the pad more efficiently than before, and it is possible to efficiently cut the polishing pad and discharge the pad dust. For this reason, the change of the pad cutting rate can be reduced, and the polishing rate can be maintained without changing the pressing load or the particle diameter of the diamond abrasive grains fixed to the conditioner surface. Therefore, the polishing rate and uniformity of the film to be polished on the semiconductor wafer can be stabilized. As a result, overpolishing and insufficient polishing of the film to be polished can be prevented, and the manufacturing yield and reliability of the semiconductor device can be improved. Further, the conditioner life can be extended, and the manufacturing cost of the semiconductor device can be suppressed.

  The embodiments described above do not limit the technical scope of the present invention, and various modifications and applications can be made within the scope of the present invention other than those already described.

  The present invention has an effect of stabilizing the polishing rate and polishing rate uniformity of a film to be polished on a semiconductor wafer, and is useful as a semiconductor device manufacturing apparatus and a semiconductor device manufacturing method.

The schematic perspective view which shows the structure of the CMP part in the 1st Embodiment of this invention. Sectional drawing which shows the structure of the conditioner in the 1st Embodiment of this invention The figure which shows the relationship between the pad cutting rate and the conditioner use time in the 1st Embodiment of this invention. The figure which shows the relationship between the polishing rate in 1st Embodiment of this invention, polishing rate uniformity, and conditioner use time. 7 is a flowchart showing a manufacturing process of a semiconductor device according to the second embodiment of the present invention. Cross-sectional process diagram showing the process of forming copper wiring of a semiconductor device by CMP Schematic perspective view showing the configuration of a conventional CMP unit

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Platen 101 Polishing pad 102 Semiconductor wafer 103 Head 104 Conditioner 105 Slurry supply mechanism 106 Conditioner holder 107 Abrasive grain holding plate 108 Base metal 109 Extrusion amount 110 Plate thickness 111 Concave depth 120 Diamond abrasive grain 201 Interlayer insulating film 202 Barrier metal 203 Copper film

Claims (2)

A semiconductor device manufacturing apparatus that polishes the polishing target surface by relatively moving the semiconductor substrate and the polishing pad in a state where the polishing target surface of the semiconductor substrate is pressed against the polishing pad,
A conditioner that contacts the polishing pad and conditions the polishing pad,
A plate to which abrasive grains are fixed;
A base on which the plate is fixed;
With
An apparatus for manufacturing a semiconductor device, wherein an amount of protrusion of the plate surface from the base metal is 140 μm or more and 200 μm or less. In a state where the polishing target surface of the semiconductor substrate is pressed against the polishing pad, the method for manufacturing a semiconductor device for polishing the polishing target surface by relatively moving the semiconductor substrate and the polishing pad,
Conditioning the polishing pad by bringing a conditioner protruding in a range of 140 μm or more and 200 μm or less from the base metal on which the abrasive grains are fixed into contact with the polishing pad. ,
Polishing the surface to be polished with the conditioned polishing pad;
A method for manufacturing a semiconductor device, comprising:

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