JP2006278977A - Manufacturing method of semiconductor device and polishing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for acquiring sufficient polishing speed and not shortening a life of a polishing pad even if a concentration of an abrasive grain in a polishing agent is low or a non-foamed type polishing pad is used in a chemical mechanical polishing process. <P>SOLUTION: In the chemical mechanical polishing process, the surface of the polishing pad is conditioned with at least by first and second conditioning disks whose surface conditions are different from each other. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention generally relates to a CMP (Chemical Mechanical Polishing) method, and more particularly to a method of manufacturing a semiconductor device including a polishing step by the CMP method.

In manufacturing a semiconductor device, a CMP (Chemical Mechanical Polishing) method is used to planarize a substrate or remove an insulating film or a conductive film. The CMP technique is particularly important in a multilayer wiring structure using a low resistance metal such as Cu as a wiring layer. The CMP method is also important in the polishing of optical elements such as silicon wafer surface treatment, magnetic disk surface treatment, and lenses.
JP 2003-165048 A

  FIG. 1 shows a configuration of a typical CMP apparatus 10.

  Referring to FIG. 1, a CMP apparatus 10 includes a platen 11 that is rotated by a drive source (not shown), and a polishing pad 12 is fixed on the platen 11. On the other hand, the semiconductor substrate 14 is held on a carrier 13 that is rotated by another drive source, and is pressed against the polishing pad 12 that rotates together with the platen 11 with a predetermined polishing pressure. At that time, an abrasive 16 is dropped on the polishing pad 12, and the surface of the semiconductor substrate is chemically mechanically polished by the action of the abrasive held on the polishing pad 12. By such chemical mechanical polishing, the insulating film and the conductive film on the substrate are polished individually or simultaneously.

  In such a CMP apparatus 10, the surface of the polishing pad 12 is fixed with hard abrasive grains such as diamond and ceramics and rotated by another drive source (not shown) so that uniform and efficient polishing is performed. The conditioning disc 15 is ground or conditioned. In general, such conditioning of the polishing pad 12 is performed during polishing of the semiconductor wafer or at the stage where polishing is completed, and is also referred to as dressing or sharpening. Such conditioning removes the surface of the polishing pad and exposes a new pad surface.

  FIG. 2 shows a cross-sectional view of a self-foaming type polishing pad generally used in the CMP method.

  Referring to FIG. 2, the independent foam type polishing pad has fine foam portions (called pores) 12 </ b> P having a diameter of several μm to several tens of μm formed independently from each other on the pad surface and inside. The abrasive is held in the recess 12U formed by such a foamed portion on the pad surface. At this time, since the foamed portions are independent from each other, the abrasive does not penetrate into the polishing pad. Therefore, the polishing is in comparison with the continuous foam type polishing pad in which the abrasive penetrates into the polishing pad. It is possible to reduce the consumption of the agent.

  On the other hand, in such an independent foaming type polishing pad, there arises a problem that processing waste and reactive organisms generated during polishing remain in the foamed portion and clogging occurs on the surface of the polishing pad. When such clogging occurs, the polishing rate decreases, the polishing becomes unstable, and the polishing uniformity is also deteriorated.

  Therefore, conventionally, every time the polishing pad is used for a predetermined time, the surface of the polishing pad is conditioned by, for example, the conditioning disk 15 shown in FIG. 1, and the polishing pad surface is treated with the processing waste indicated by reference numeral 12X as shown in FIG. It has been scraped off.

  2. Description of the Related Art Conventionally, in a polishing pad used for manufacturing a miniaturized semiconductor device, an independent foam type polishing pad as shown in FIG. 2 is mainstream. However, since this type of polishing pad includes a foam 12P, a manufacturing process is performed. Due to this, it is inevitable that a certain degree of variation occurs. Such manufacturing variations of the polishing pad may cause problems that cannot be ignored such as changes in the polishing rate, deterioration of polishing uniformity, and increase in polishing time in the recent manufacture of ultrafine semiconductor devices. In addition, the polishing pad having the foam 12P in the inside is flexible, and therefore the polishing pad follows the step structure of the surface to be polished even if a structure having a step on the surface is flattened by chemical mechanical polishing. Since the structure is deformed, there is a problem that a level difference cannot be sufficiently eliminated particularly when a miniaturized structure is polished, or dishing occurs when a flat structure is polished.

  In order to solve these problems, recently, use of a non-foaming type polishing pad shown in FIG. 4 has been proposed.

  Referring to FIG. 4, the non-foaming type polishing pad is formed mainly from a material such as polyurethane as in the case of the conventional continuous foaming type polishing pad, but does not include a foam inside. Since the non-foaming type polishing pad does not contain a foam inside, the difference between individuals is small, and manufacturing variations can be suppressed. In addition, since it does not include a foam that acts as a mechanical buffer during polishing, the non-foaming type polishing pad has greater rigidity than the foaming type polishing pad, and therefore even when a structure having a step is polished, It effectively acts on the step, suppresses dishing, and promotes flattening of the substrate surface.

  On the other hand, since the non-foaming type polishing pad does not include the foamed portion 12P as shown in FIG. 2, the holding ability of the abrasive is inferior compared with the foaming type polishing pad, and a desired polishing rate may not be obtained.

  FIG. 5 shows a comparison of polishing rates when the plasma oxide film formed on the silicon wafer is polished using the continuous foaming polishing pad and the non-foaming polishing pad in the CMP apparatus of FIG. However, in the experiment of FIG. 5, the polishing pressure was set to 4 psi, the rotation speed of the polishing carrier 13 and the rotation speed of the polishing platen 11 were set to 90 rpm and 80 rpm, respectively, and polishing was performed while supplying slurry at a flow rate of 200 ml / min. Yes.

  As can be seen from FIG. 5, the polishing rate when the non-foaming type polishing pad is used is about 16% lower than that when the foaming type polishing pad is used. In the experiment of FIG. 5, the abrasive concentration in the used abrasive was relatively high at 15 wt%, and therefore the decrease in the polishing rate when using the non-foaming type polishing pad was considered to be within about 16%. It is done.

  On the other hand, in the CMP process, scratches that occur characteristically in this process have become a big problem. Conventionally, it is effective to reduce the concentration of abrasive grains in the abrasive to reduce such scratches. It is known that Scratches occur for various reasons, such as when the abrasive grains dispersed in the abrasive form agglomerate to form coarse particles. Such scratches reduce the manufacturing yield of semiconductor devices. This suppression has always been an important issue in CMP technology. Further, if the abrasive concentration in the polishing agent is reduced in this way, the consumption of the abrasive grains is reduced together with the scratch, so that an effect of reducing the manufacturing cost of the semiconductor device can be expected. However, if the abrasive concentration is reduced in the CMP process using such a non-foaming type polishing pad, the polishing rate is seriously lowered.

  In one aspect, the present invention provides a method of manufacturing a semiconductor device including a step of chemically and mechanically polishing a substrate on a polishing pad, wherein the chemical mechanical polishing step includes at least a surface of the polishing pad having a different surface state. There is provided a method of manufacturing a semiconductor device, comprising a step of conditioning with first and second conditioning disks.

  In another aspect, the present invention includes a step of chemically mechanically polishing an object on a polishing pad, and a step of conditioning the surface of the polishing pad with at least first and second conditioning disks having different surface states. A chemical mechanical polishing method is provided.

  According to the present invention, when a non-foaming type polishing pad is used as the polishing pad, or when it is difficult to ensure a sufficient polishing rate during chemical mechanical polishing, such as when the abrasive grain concentration in the polishing agent is low. However, by conditioning the surface of the polishing pad with at least the first and second conditioning disks having different surface states, it is possible to hold a sufficient amount of abrasive on the polishing pad, and a sufficient polishing rate. Is secured. Further, by intermittently using the first conditioning disk that forms a large surface roughness on the polishing pad surface, or by alternately using the first conditioning disk and the second conditioning disk, Excessive wear of the polishing pad can be suppressed and the life can be extended.

  According to the present invention, by using a non-foaming type polishing pad, it is possible to achieve excellent flatness on the surface of the substrate to be processed while ensuring a sufficient polishing rate, and further by reducing the abrasive concentration, The generation of scratches on the surface of the substrate to be processed can be reduced while ensuring the polishing rate.

[principle]
First, the principle of the present invention discovered by the inventor in research that forms the basis of the present invention will be described.

  FIG. 6 shows the relationship between the abrasive concentration in the abrasive and the polishing rate when the foaming type polishing pad of FIG. 2 is used.

  In this experiment, in a polishing agent in which silica particles are dispersed in pure water, the concentration of silica particles was adjusted to 5, 10 and 15 wt%, respectively, and the polishing rate of the plasma oxide film formed on the silicon wafer was investigated. ing. At that time, the polishing is performed using the CMP apparatus 10 of FIG. 1, the polishing pressure is set to 3 psi, the polishing carrier 13 and the polishing platen 11 are rotated at the rotation speeds of 90 rpm and 80 rpm, respectively, and the above-mentioned abrasive is flowed at 200 ml / min It went while supplying with.

  Referring to FIG. 6, a result in which the polishing rate and the abrasive concentration are almost proportional was obtained. Further, from the results of FIG. 6, it was found that the polishing rate was drastically lowered when the abrasive concentration in the polishing agent was reduced to 5 wt% or less, although it depends on the grain size of the abrasive grains.

  The results in FIG. 6 indicate that depending on the components of the abrasive and the characteristics (shape, particle diameter, etc.) of the abrasive, when the abrasive concentration in the abrasive is below a certain level, the polishing rate may decrease rapidly. Is expected.

  FIG. 7 shows the results when a similar experiment is performed on a Cu film formed on a silicon substrate via a silicon oxide film.

  Referring to FIG. 7, in this experiment, the Cu film was polished by setting the polishing pressure to 3 psi, the rotation speed of the polishing carrier 13 to 80 rpm, the rotation speed of the polishing platen 11 to 70 rpm, and the polishing agent to 200 ml / min. It was carried out while supplying at a flow rate of. In the experiment of FIG. 7, the abrasive grain concentration in the abrasive is set to 3.5 wt%. In the case of polishing the Cu film, the polishing conditions are unified between the independent foam type polishing pad and the non-foaming type polishing pad, similarly to the polishing of the oxide film.

  From FIG. 7, it can be seen that the polishing rate of the non-foaming type polishing pad is greatly reduced to 33.5% as compared with the case of using the foaming type pad. This is presumably because the decrease in the polishing rate appears more remarkably because the abrasive grain concentration in the abrasive is low.

  Thus, when a non-foaming type polishing pad is used as the polishing pad or when the abrasive concentration in the polishing agent is low, the polishing rate may decrease, making it difficult to obtain a desired high polishing rate. become.

  As one of the measures for solving the decrease in the polishing rate in the case of using the non-foaming type polishing pad described above or in the case of using the non-foaming type polishing pad in combination with an abrasive having a low abrasive concentration, FIG. It is conceivable to form grooves on the surface of the polishing pad by the conditioning disk 15.

  As shown in FIG. 8A, in the non-foaming type polishing pad, the polishing pad does not have a foam (pore). Therefore, the amount of the abrasive 16 held on the surface of the polishing pad 12 is as shown in FIG. Less than the foam type polishing pad shown in B). That is, when the non-foaming type polishing pad is used, the amount of the abrasive supplied to the surface of the semiconductor wafer to be polished is smaller than that when the foaming type polishing pad is used, and as a result, as shown in FIG. It is considered that the polishing rate decreases as described.

  Therefore, in order to retain the abrasive in the non-foaming type polishing pad in the same manner as the foaming type polishing pad, as described above, the conditioning disk 15 forms a fine groove on the surface of the polishing pad 12, and the foam It can be considered as an alternative.

  FIG. 9 is a diagram schematically showing a cross section of a conventionally used conditioning disk 15.

  Referring to FIG. 9, the conditioning disk 5 is composed of a washer 15A and hard abrasive grains 15C made of, for example, diamond fixed on the washer 15A with an alloy layer 15B. As the washer 15A, Stainless steel or the like is used, and diamond is used as the abrasive grains 15C. Further, as the alloy layer 15B for fixing the abrasive grains 15C to the washer 15A, a Ni-based alloy is often used. The fixing of the abrasive grains 15C onto the washer 15A is performed by forming the alloy layer 15B by an electrodeposition method, a plating method, a diffusion method, or the like.

  Such characteristics of the conditioning disk 15 are mainly determined by the hard abrasive grains and the arrangement method thereof.

  Hereinafter, the case where the conditioning disk 15 uses diamond as the hard abrasive grains 15C will be described.

  In such a conditioning disk 15, the grinding characteristics of the polishing pad vary greatly depending on the size and shape of the diamond used in the conditioning disk.

  For example, when the diameter of the diamond abrasive grains 15C is small and is granular or isotropic, the ability to grind the polishing pad, that is, the pad grinding speed and the amount of pad grinding decreases. As a result, the life of the polishing pad 12 is extended, but there are cases where sufficient conditioning cannot be performed.

  On the contrary, when diamond particles having irregular shapes and sharp points are used as the abrasive grains 15C, the grinding speed of the polishing pad 12 is increased and the polishing pad can be efficiently conditioned. On the other hand, the life of the polishing pad 12 is reduced, leading to an increase in the manufacturing cost of the semiconductor device. In addition, sharp and sharp diamond abrasive grains are easily cracked or chipped and are likely to be scratched. When scratches occur, deep scratches occur on the surface of the semiconductor substrate, and the yield decreases.

  Commercially available products are available for both types of conditioning pads, but generally, diamond abrasive grains having a substantially isotropic shape are often used as the abrasive grains 15C. In this case, a conditioning disk on which coarse diamond abrasive grains are arranged is used depending on the situation. When conditioning is performed using a conditioning disk carrying coarse diamond abrasive grains, grooves deeper than the conditioning disk carrying granular diamond abrasive grains can be formed on the surface of the polishing pad 12.

  In general, the size of the foam in the foam type polishing pad shown in FIG. 2 is about several μm to several tens of μm, whereas the size of the diamond abrasive grains 15C in FIG. 9 is at least about 50 μm. Has a size of 100 μm to several hundred μm, and by using such a conditioning disk, a groove can be formed deeper than the foam on the surface of the polishing pad. That is, the conditioning by the conditioning disk 15 in FIG. 9 is effective even in the foaming type polishing pad, and a larger amount of abrasive can be held on the surface of the polishing pad.

That is, in the CMP apparatus of FIG. 1, by using a conditioning disk on which coarse diamond abrasive grains are arranged as the conditioning disk 15, even when the foaming type polishing pad described above with reference to FIG. Even when the non-foaming type polishing pad described in FIG. 4 is used, an increase in the polishing rate can be expected.
Further, as a result of the formation of deep grooves in the polishing pad 12, a larger amount of abrasive grains contained in the polishing agent can be held on the surface of the polishing pad 12 for a longer time.

  FIG. 11 (A) shows the semiconductor substrate 21 and the abrasive grains in the polishing agent 16 and the polishing pad when the semiconductor substrate 21 is polished when no groove is formed on the surface of the non-foaming polishing pad 12. FIG. 11B schematically shows the relationship between the semiconductor substrate 21 and the polishing agent 16 when a deep groove is formed on the surface of the same non-foaming polishing pad 12 by the conditioning disk 15. 2 is a diagram schematically showing the relationship between abrasive grains and a polishing pad 12. FIG.

  Referring to FIG. 11A, when a groove is not formed on the polishing pad 12, the semiconductor substrate 21 is formed on the surface of the polishing pad 12 to which the polishing agent is supplied. However, as the polishing proceeds, the abrasive grains in the abrasive 16 are gradually crushed by pressure and friction. Here, new abrasive grains may be supplied along the surface of the polishing pad 12 so as to replace the worn abrasive grains, but the flow of the abrasive along the surface of the polishing pad 12 is difficult to control, There may occur a case where abrasive grains are depleted in a specific region on the polishing pad 12. In such a case, the polishing rate of chemical mechanical polishing decreases as the time becomes longer and the abrasive grains are consumed.

  On the other hand, when grooves are formed on the surface of the polishing pad by the conditioning disk 15 as shown in FIG. 11 (B), a large amount of abrasive grains in the abrasive 16 are held inside the grooves. Even if the abrasive grains are consumed, new abrasive grains are stably supplied on the spot, so that stable chemical mechanical polishing can be performed for a long time without decreasing the polishing rate.

  Thus, the polishing speed of the semiconductor wafer varies depending on the surface state of the polishing pad 12 used, and the surface state of the polishing pad 12 depends on the surface state of the conditioning disk 15 used. Even in the case of a conditioning disk in which diamonds having the same shape are arranged, the state may change if the arrangement of diamond abrasive grains 15C on the disk is different.

  FIGS. 11A to 11D show examples of conditioning disks in which the arrangement of the diamond abrasive grains 15C is changed. However, in FIGS. 11A to 11D, the same reference numerals are given to the portions described above, and the description thereof is omitted.

  Referring to FIG. 11A, in this example, diamond crystals are oriented as the abrasive grains 15C so that a flat crystal plane faces upward. On the other hand, in the example of FIG. 11B, the diamond crystal is oriented so that the corners thereof face upward. In the configuration of FIG. 11 (B), it is possible to roughen the polishing pad more effectively by turning the corners of the diamond abrasive grains 15C upward.

  FIG. 11C increases the density of diamond abrasive grains 158C formed on the conditioning disk 15, while FIG. 11D decreases the thickness of the fixed layer 15B that fixes the diamond abrasive grains 15C. The exposure amount of the abrasive grains 15C is increased. In any of these configurations, the surface of the polishing pad 12 can be more effectively ground as compared with the configuration of FIG. 11B and 11D, the depth of the groove formed on the surface of the polishing pad 12 is also increased. FIG. 12A shows the state of the polishing pad surface when the surface of the non-foaming polishing pad 12 is ground using the conditioning disk of FIG. 11A, while FIG. 12B shows the state of FIG. A state of the surface of the polishing pad when the surface of the same non-foaming type polishing pad 12 is ground using the conditioning disk of (B) or FIG.

  Thus, if the method of disposing the diamond abrasive grains 15C on the washer 15A in the conditioning disk 15 is different, when the semiconductor wafer is polished on the polishing pad conditioned by such a conditioning disk, the polishing speed varies. . Further, comparing the case where the diamond abrasive grains 15C are regularly arranged on the washer 15A is compared with the case where the diamond abrasive grains 15C are randomly arranged, the result that the polishing speed is higher when the diamond abrasive grains 15C are randomly arranged although the same diamond is used. May appear.

  A method for arranging diamond on the conditioning disk is described in, for example, Japanese Patent Application Laid-Open No. 2002-187065.

  FIG. 13 shows a condition that a commercially available foam-type polishing pad is conditioned using the two types of conditioning disks A and B shown in FIGS. 14A and 14B, and the polishing pad thus conditioned is shown in FIG. It is a figure which shows the time change of the grinding | polishing speed | rate at the time of using as the polishing pad 12 in a CMP apparatus, and polishing a plasma oxide film. However, in the experiment of FIG. 13, the polishing pressure was set to 4 psi, the rotation speed of the polishing carrier 13 and the rotation speed of the polishing platen 11 were set to 90 rpm and 80 rpm, respectively, and the abrasive grain concentration in the abrasive was set to 18 wt%. , While supplying the abrasive at a flow rate of 200 ml / min. The conditioning of the polishing pad 12 is performed by setting the pressure of the conditioning disk 15 to 5 psi and polishing the silicon oxide film while performing conditioning each time.

  Referring to FIG. 14 (A), the conditioning disk A corresponds to the disk of FIG. 11 (A), and a granular substantially isotropic diamond crystal is used as the abrasive grains 15C. The abrasive grains 15C are formed from the fixed layer 15B. It protrudes by a distance of about 50 to 100 μm. On the other hand, the conditioning disk B corresponds to the disk of FIG. 11B or FIG. 11D and uses a rough type irregularly shaped diamond crystal as the abrasive grains 15C. At that time, the abrasive grains 15C protrude from the fixed layer 15B by a distance of about 100 to 200 μm. In the conditioning disk B of FIG. 14B, the diamond abrasive grains 15C are randomly arranged on the washer 15A, and a high grinding speed is realized with respect to the polishing pad 14.

  On the other hand, in the conditioning disk A of FIG. 14A, the diamond abrasive grains 15C are regularly arranged in a lattice shape. As a result, when the polishing pad 12 conditioned by the conditioning disk B is used, the grinding speed for the polishing pad 12 is about twice as high as that when the conditioning disk A is used.

  Referring to FIG. 13, the polishing rate immediately after conditioning is larger when the polishing pad 12 is conditioned with the conditioning disk B. This is because the disk A is used for conditioning and the disk A is used. This is probably because the surface of the used polishing pad 12 is rough. On the other hand, since the abrasive concentration in the abrasive is high and about 18 wt%, the polishing rate is increased only by about 10%.

  On the other hand, as can be seen from FIG. 13, when conditioning of the polishing pad 12 is continued with the conditioning disk B, a phenomenon is found in which the polishing rate of the silicon oxide film sharply decreases when the conditioning integration time exceeds 5 hours. It was. On the other hand, when the polishing pad conditioned by the conditioning disk A is used as the polishing pad 12, it can be seen that a stable polishing rate can be obtained even when the integrated conditioning time reaches 9 hours.

  This is because the grinding speed of the polishing pad by the conditioning disk B is very high, so that the polishing pad 12 is rapidly consumed. Therefore, the groove processed on the surface of the polishing pad also becomes shallow, and the polishing agent is sufficiently semiconductor. This is probably because the wafer cannot be supplied. On the other hand, when the disk A is used for conditioning the polishing pad 12, the grinding speed of the polishing pad is low, so that the polishing pad consumes little even after conditioning for a long time. Maintains an effective depth over time. As a result, it can be seen that the abrasive is stably supplied to the surface of the semiconductor wafer and stable polishing is realized.

  Next, a similar experiment was performed using a Cu film.

  In this experiment, a non-foaming type polishing pad was used as the polishing pad 12, and the polishing was performed by setting the polishing pressure to 3 psi, rotating the polishing carrier 13 at 80 rpm, and the polishing platen 11 at 70 rpm. The polishing agent containing abrasive grains at a concentration of 2 wt% is carried out at a flow rate of 200 ml / min. Further, the conditioning of the polishing pad 12 is performed using the disks A and B as the conditioning disk 15, and any of the disks is used at a pressure of 5 psi.

  FIG. 15 shows the relationship between the polishing rate thus obtained and the integrated conditioning time.

  Referring to FIG. 15, when a Cu film is polished using a non-foaming type polishing pad and an abrasive having a low abrasive concentration, the foaming type polishing pad is oxidized in combination with an abrasive containing a high concentration of abrasive grains. It can be seen that the effect of the conditioning disk B is more remarkable than when the film is polished, and the polishing rate is improved by about 70% at the maximum.

  However, although the polishing rate becomes very large as described above, the life of the polishing pad is extremely shortened, and when the integrated conditioning time exceeds 6 hours, the grooves processed on the surface of the polishing pad are completely lost. It was confirmed. On the other hand, when the conditioning disk A was used, the polishing pad grooves remained sufficiently even after conditioning for about 16 hours, and an estimated difference of about four times or more in the life of the polishing pad 12 was obtained.

  Thus, according to the research that forms the basis of the present invention, by using the conditioning disk B, it is possible to avoid a decrease in the polishing rate associated with the use of a low abrasive concentration abrasive or a non-foaming type polishing pad. However, it has been found that the life of the polishing pad is shortened. In addition, when conditioning B was used, it was observed that the uniformity of the semiconductor wafer deteriorated.

Therefore, in order to solve these newly generated problems, the present invention proposes to use a combination of two conditionings having different surface states when conditioning a polishing pad.

[First embodiment]
The first embodiment of the present invention will be described below with reference to FIG. However, Table 1 shows the conditioning conditions, and FIG. 16 shows a chemical mechanical polishing flowchart according to the first embodiment of the present invention. Also in this embodiment, the Cu film is polished using the CMP apparatus 10 of FIG.

図１６を参照するに、新品の研磨パッドを研磨プラテン１１上に、前記研磨パッド１２として設置し、さらに先の図１４（Ｂ）のコンディショニングディスクＢを、前記コンディショニングディスク１５とＣＭＰ装置１０に装着し、研磨パッド１２のブレイクインを行う。この工程では、表１に示すように、研磨プラテン１１を７０ｒｐｍの回転数で回転させながら、８７ｒｐｍの回転数で回転させたコンディショニングディスク１５を、前記研磨パッド１２に、９ｌｂｓ（ポンド）の押圧力で押圧する。この条件で前記研磨パッド１２のブレイクインを、１８００秒間にわたり実施する。表１の「ブレイクイン時」を参照。

Referring to FIG. 16, a new polishing pad is installed on the polishing platen 11 as the polishing pad 12, and the conditioning disk B shown in FIG. 14B is mounted on the conditioning disk 15 and the CMP apparatus 10. Then, a break-in of the polishing pad 12 is performed. In this step, as shown in Table 1, the conditioning disk 15 rotated at a rotational speed of 87 rpm while rotating the polishing platen 11 at a rotational speed of 70 rpm is pressed against the polishing pad 12 by 9 lbs (pounds). Press. Under this condition, the break-in of the polishing pad 12 is performed for 1800 seconds. Refer to “Break-in” in Table 1.

  Next, in step 2 in FIG. 16, the conditioning disk 15 is replaced from the disk B in FIG. 14B to the disk A in FIG. 14A, and the Cu film is polished by polishing pressure 3 psi and polishing carrier 13 The number of rotations is set to 80 rpm, the number of rotations of the polishing platen 11 is set to 70 rpm, and an abrasive having an abrasive concentration of 2 wt% is supplied at a flow rate of 200 ml / min. At that time, the polishing rate is measured. In step 2, the conditioning is performed for 24 seconds under a conditioning pressure of 5 lb with the number of revolutions of the conditioning disk 15 set to 87 rpm. Refer to “Wafer Polishing” in Table 2.

  Next, after the wafer polishing and the polishing rate acquisition in the step 2, in the experiment of FIG. 15, accelerated conditioning is performed in order to increase the conditioning integration time. Accelerated conditioning is performed by a method of performing conditioning for a certain period of time while flowing pure water. Refer to “Acceleration” in Table 1.

  Further, in the embodiment of FIG. 16, as a result of the acceleration processing in the step 3, the wafer is polished in step 4 at the stage where the integrated conditioning time has reached a constant, and the polishing rate is acquired.

  Further, in step 5, the conditioning disk 15 is changed from the disk A to the disk B when the polishing rate is lowered, and the break-in of the polishing pad 12 is again performed for 600 seconds under the condition of “rebreak-in” in Table 1. carry out.

  Further, in Step 6 and subsequent steps in FIG. 16, the processing of Step 1 to Step 5 was repeated to obtain polishing rate data.

  FIG. 17 shows the polishing rate of the Cu film obtained by the experiment of FIG. However, in the figure, “disk A” uses only disk A as the conditioning 15, “disk B” uses only disk B as the conditioning disk 15, and “disk A + B” The polishing rate of the Cu film when the disk A and the disk B are used together as the conditioning disk 15 is shown.

  Referring to FIG. 17, in the experiment of “Disk A + B”, rebreaking is performed at the timing of the arrow according to the flowchart of FIG. 15, but in this case, the polishing rate immediately after the breakin is high. Thereafter, the conditioning disk 15 is changed to the disk A, and it can be seen that the polishing rate gradually decreases when the conditioning disk 15 is continuously used. Therefore, in the experiment of “Disk A + B”, when the polishing speed is lowered to some extent, the disk B is used as the conditioning disk 15 and the polishing pad is broken again for a predetermined time, so that the polishing speed is close to the initial value. The value is restored. As described above, it was confirmed that when the disk A and the disk B were used in combination as the conditioning disk 15, the life of the polishing pad was almost the same as when the conditioning was performed only with the disk A.

  On the other hand, when the conditioning is performed only with the disk B, the polishing pad 12 is worn out when the integrated conditioning time exceeds 6 hours. Further, when conditioning is performed only with the disk A, only a low polishing rate can be obtained.

  In this way, by conditioning the polishing pad 12 in combination with the disks A and B, it is possible to realize a high polishing rate and at the same time to extend the life of the polishing pad.

In the experiment of the flowchart of FIG. 16, the CMP apparatus 10 of FIG. 1 is used and polishing is performed while exchanging the disk A and the disk B as the conditioning disk 15. However, depending on the CMP apparatus, the conditioning disk may be used simultaneously. Some types can be installed more than one. In such a case, it is possible to execute a polishing process equivalent to that of FIG. 15 without replacing the conditioning disk. It is also possible to operate two conditioning disks simultaneously and perform conditioning at the same time.

[Second Embodiment]
Next, a manufacturing process of the semiconductor device according to the second embodiment of the present invention including the Cu damascene process will be described with reference to FIGS. 18 (A) to 18 (E).

Referring to FIG. 18A, an insulating film 21 made of SiO ₂ , SiOC, SiC, SiON, SiN, BPSG, or the like is formed on a semiconductor substrate (not shown) such as a transistor formed on the semiconductor substrate. It is formed so as to cover an element (not shown). The insulating film 21 may be formed directly on the semiconductor substrate or may be formed so as to cover the insulating film formed on the semiconductor substrate.

  Next, in the step of FIG. 18B, a wiring groove 21G corresponding to a desired wiring pattern is formed in the insulating film 21 by etching. In the case of the dual damascene method, a via hole is formed in the wiring groove 21G so as to expose the conductive layer under the insulating film 21.

  Further, in the step of FIG. 18C, the surface of the insulating film 21 is made of tantalum (Ta), titanium (Ti), or a nitride film thereof (TaN, TiN) so as to include the side wall surface and the bottom surface of the wiring groove 21G. Is covered with a barrier metal film 22 made of

  Next, in the step of FIG. 18D, a Cu film 23 is formed on the barrier metal film 23 so that the Cu film 23 fills the wiring groove 21G. The formation of the Cu film 23 is performed by a sputtering method, a plating method, or a combination thereof.

  Further, in the step of FIG. 18E, the Cu film 23 is polished and removed together with the barrier metal film 23 from the surface of the insulating film 21 by using the CMP apparatus 10 of FIG. 1, and the Cu pattern 23G becomes the wiring groove 21G. In addition, a wiring structure embedded through the barrier metal film 22 is obtained.

  In this example, the CMP process of FIG. 18E is performed using a non-foamed polishing pad and a polishing agent in which colloidal silica is dispersed in a solvent as abrasive grains at a concentration of 1.5 wt%. Here, as the solvent, an organic acid that forms a complex with Cu, an oxidizing agent that oxidizes Cu, and an anticorrosive agent that forms a protective film on the surface of Cu are added to ultrapure water, or ultrapure water. In this case, the surface of hydrogen peroxide and an organic acid is used, and when the polishing pad 12 is to be broken in, the disk B of 14 (B) is used as the conditioning disk 15. 14 (A) disk A is used.

  FIG. 19A is a flowchart showing an experiment corresponding to this example.

  Referring to FIG. 19A, in step 11, a non-foaming type polishing pad is mounted on the CMP apparatus 10 of FIG. 1 as a polishing pad 12, and this is used as the conditioning disk 15 by using the disk B of FIG. Then, the break-in of the polishing pad 12 is performed under the conditions of Table 1 described earlier (“break-in time”).

  Next, in step 12, using the disk A of FIG. 14A as the conditioning disk 15 and conditioning the polishing pad 12, the polishing of the Cu film 23 of FIG. (Polishing pressure = 3 psi; carrier rotation speed = 80 rpm; platen rotation speed = 70 rpm; abrasive flow rate = 200 ml / min). The polishing pad 12 is conditioned under the conditions shown in Table 1 (“Wafer Polishing”).

  Further, in step 13, acceleration conditioning of the polishing pad 12 is performed under the conditions shown in Table 1 (“acceleration”) while using the disk A as the conditioning disk 15. In step 14, rebreaking of the polishing pad 12 is performed. This is performed under the conditions shown in Table 1 (at the time of rebreaking).

  Further, in step 15, the Cu film 23 was polished once again under the same conditions as in step 12.

  In this example, in order to further verify the effect of the process of FIG. 19A, a comparative experiment of FIG. 19B and FIG. 19C was performed.

  In the experiment of FIG. 19B, the same polishing was performed except that the non-foaming type polishing pad and the disk B were used and the step 14 (rebreak-in) in FIG. 19A was omitted.

  That is, in step 21, break-in similar to step 11 is performed, and in step 22, the Cu film 23 is polished similarly to step 12 while the disk B is mounted as the conditioning disk 15.

  Further, in step 23, acceleration conditioning is performed in accordance with the conditions in Table 1 with the disc B mounted as the conditioning disc 15. In step 24, step 14 in FIG. The polishing of the Cu film 13 is performed under the same conditions as in Step 22.

  In the experiment of FIG. 19C, the same polishing was performed except that the foam type polishing pad and the disk A were used and the step 14 (rebreak-in) in FIG. 19A was omitted.

  That is, in step 31, break-in similar to step 11 is performed using the disk A as the conditioning disk 15, and in step 32, the Cu film 23 is polished as in step 12 while the disk A is mounted as the conditioning disk 15. It is carried out.

  Further, in step 33, acceleration conditioning is performed in accordance with the conditions shown in Table 1 with the disk A mounted as the conditioning disk 15. In step 34, step 14 in FIG. The Cu film 23 is polished under the same conditions as in the step 32.

  FIG. 20 shows an evaluation of a damascene structure polished in this manner.

  In general, in a Cu damascene structure processed by the CMP method, since the polishing rate of the Cu film is higher than the polishing rate of the insulating film constituting the interlayer insulating film, a step (dishing) is likely to occur in the region where the damascene wiring is formed. On the other hand, in order to realize high reliability of the semiconductor device, it is preferable to suppress such a step as much as possible.

  In this embodiment, therefore, the polishing process shown in FIGS. 19A to 19C is evaluated between a region where no wiring pattern is formed and a damascene wiring region where a wiring pattern is formed, as shown in FIG. This was done by measuring the step. Measurement is performed at the center and the outer periphery of the substrate.

  FIG. 21 shows the measurement results.

  Referring to FIG. 21, (A) corresponds to the process of FIG. 19 (A), that is, the process of the present embodiment, but the measured step is very small, and the step increases even after acceleration conditioning. I understand that there is nothing.

  On the other hand, FIG. 21B corresponds to the case where only the disk B is used in the non-foaming type polishing pad of FIG. 19B, but the step generated by the first polishing in step 22 is small. Good results have been obtained. However, in this case, after performing acceleration conditioning in step 23, it can be seen that the level difference is very large at the outer periphery of the semiconductor substrate. This is presumably because the polishing pad 12 that is in contact with the outer peripheral portion of the semiconductor substrate is worn away at the outer peripheral portion, and the grooves are almost lost. That is, since the grinding amount of the polishing pad is large in the disk B, the groove of the polishing pad disappears in a short time, and the polishing agent is not sufficiently supplied to the surface of the polishing pad, which indicates that polishing is not performed. it is conceivable that.

  On the other hand, in FIG. 21, (C) shows the case where the foaming type polishing pad is used in combination with the disk A, but there is no big difference between step 32 and step 34, and polishing is shown in FIG. 19 (B). More stable than the process. However, as compared with the process of FIG. 19A, it can be seen that the level difference is much increased.

  As described above, according to the present embodiment, the conditioning disk 15 is the disk B used when the polishing pad is broken in, and the disk B is used during the polishing. Even when using abrasives with a low grain concentration, it is possible to stably achieve a large polishing rate without shortening the life of the polishing pad, suppressing step differences, and achieving excellent chemical mechanical polishing with less scratches. It becomes possible.

In the present invention, the insulating film 21 may be Si, SiO, SiO ₂ , SiOC, SiC, SiON, SiN, BPSG, or a composite film thereof. Further, instead of the Cu film 23, it is also possible to use W, Ti, Al, Ta, Ag, Au, Pt, Ru, polysilicon, amorphous silicon, and an oxide film or nitride film thereof.

  In the above invention, the chemical mechanical polishing process has been described in relation to the formation of the damascene structure. However, the present invention is not limited to this, and is applicable to the formation of an STI (shallow trench isolation) structure, for example. Is possible.

  Furthermore, the present invention is not limited to the manufacture of a semiconductor device, but can also be applied to polishing optical components such as lenses and magnetic disks.

  As mentioned above, although this invention was demonstrated about the preferable Example, this invention is not limited to this, A various deformation | transformation and change are possible within the summary described in the claim.

(Appendix 1)
A method of manufacturing a semiconductor device including a substrate polishing step,
The polishing step includes
Chemical mechanical polishing the substrate with a polishing agent on a polishing pad;
Conditioning the surface of the polishing pad;
Including
The method of manufacturing a semiconductor device, wherein the conditioning step includes a step of grinding the surface of the polishing pad with at least first and second conditioning disks having different surface states.

(Appendix 2)
The first and second conditioning disks form first and second surface roughnesses on the polishing pad surface, respectively, and the first surface roughness is larger than the second surface roughness. The method for manufacturing a semiconductor device according to appendix 1, wherein:

(Appendix 3)
The first and second conditioning disks are configured to grind the pad surface at first and second grinding speeds, and the first grinding speed is greater than the second grinding speed. A method for manufacturing a semiconductor device according to 1 or 2.

(Appendix 4)
The second conditioning disk grinds the surface of the polishing pad every time the substrate is polished, and the first conditioning disk grinds the surface of the polishing pad intermittently. The manufacturing method of the semiconductor device as described in any one of -3.

(Appendix 5)
5. The method of manufacturing a semiconductor device according to claim 4, wherein the first conditioning disk grinds the surface of the polishing pad simultaneously with the second conditioning disk.

(Appendix 6)
4. The method of manufacturing a semiconductor device according to claim 1, wherein the first and second conditioning disks grind the surface of the polishing pad alternately.

(Appendix 7)
7. The method of manufacturing a semiconductor device according to claim 1, wherein the second conditioning disk grinds the surface of the polishing pad simultaneously with the chemical mechanical polishing step of the object.

(Appendix 8)
Each of the first and second conditioning disks is composed of a washer and abrasive grains fixed on the washer by a fixing layer, and the shape of the abrasive grains is the first conditioning disk and the second conditioning disk. 8. The method of manufacturing a semiconductor device according to any one of Supplementary notes 1 to 7, wherein the conditioning disk is entirely different from the conditioning disk.

(Appendix 9)
Each of the first and second conditioning disks is composed of a washer and abrasive grains fixed on the washer by a fixing layer, and the grain size of the abrasive grains is the first conditioning disk and the second conditioning disk. 8. The method of manufacturing a semiconductor device according to any one of appendices 1 to 7, wherein the conditioning disk is entirely different from the conditioning disk.

(Appendix 10)
Each of the first and second conditioning disks is composed of a washer and a crystal that is fixed on the washer by a fixed layer to form an abrasive grain, and the orientation of the crystal is the first conditioning disk and the first The manufacturing method of a semiconductor device according to any one of appendices 1 to 7, wherein the conditioning disk is totally different from the conditioning disk of No. 2.

(Appendix 11)
Each of the first and second conditioning disks includes a washer and abrasive grains fixed on the washer by a fixing layer, and the density of the abrasive grains is the first conditioning disk and the second conditioning disk. 8. The method of manufacturing a semiconductor device according to any one of appendices 1 to 7, wherein the semiconductor device is different from a conditioning disk.

(Appendix 12)
Each of the first and second conditioning disks includes a washer and abrasive grains fixed on the washer by a fixed layer, and the amount of protrusion of the abrasive grains from the fixed layer is the first conditioning. The manufacturing method of a semiconductor device according to any one of appendices 1 to 7, wherein the disc and the second conditioning disc are entirely different.

(Appendix 13)
13. The method of manufacturing a semiconductor device according to appendix 12, wherein the protruding amount is 100 μm or more for the first conditioning disk and 100 μm or less for the second conditioning disk.

(Appendix 14)
14. The method of manufacturing a semiconductor device according to any one of Supplementary notes 1 to 13, wherein the polishing pad is a non-foaming type polishing pad.

(Appendix 15)
15. The method for manufacturing a semiconductor device according to any one of Supplementary notes 1 to 14, wherein the polishing agent contains abrasive grains at a concentration of 10 wt% or less.

(Appendix 16)
The method of manufacturing a semiconductor device according to any one of appendices 1 to 15, wherein the substrate is a semiconductor wafer, and the surface of the semiconductor wafer is polished in the chemical mechanical polishing step.

(Appendix 17)
The method of manufacturing a semiconductor device according to any one of appendices 1 to 15, wherein the substrate carries an insulating film, and the insulating film is polished in the chemical mechanical polishing step.

(Appendix 18)
The method of manufacturing a semiconductor device according to any one of appendices 1 to 15, wherein the substrate carries a conductive film, and the conductive film is polished in the chemical mechanical polishing step.

(Appendix 19)
Chemical mechanical polishing of the object on the polishing pad using an abrasive;
Conditioning the surface of the polishing pad, and a polishing method comprising:
The conditioning method includes a step of grinding the surface of the polishing pad with at least first and second conditioning disks having different surface states.

It is a figure which shows the structure of the CMP apparatus used by this invention. It is a figure which shows the cross-section of the conventional foaming type polishing pad. It is a figure which shows the conditioning in a foaming type polishing pad. It is a figure which shows the cross-section of a non-foaming type polishing pad. It is a figure which compares and shows the grinding | polishing characteristic of a foaming type polishing pad and a non-foaming type polishing pad. It is a figure which shows the relationship between the abrasive grain concentration in an abrasive | polishing agent, and polishing rate. It is a figure which compares and shows the grinding | polishing characteristic of a foaming type polishing pad and a non-foaming type polishing pad. (A), (B) is a figure which shows the state of the abrasive | polishing agent hold | maintained on the non-foaming type polishing pad and the foaming type polishing pad, respectively. It is sectional drawing which shows the structure of a general conditioning disk. (A), (B) is a figure which shows roughly the grinding | polishing of the board | substrate on the polishing pad from which a surface state differs. (A)-(D) are figures which show various conditioning discs. (A), (B) is a figure which shows the surface state of the polishing pad ground with the conditioning disk from which a surface state differs. It is a figure which shows the grinding | polishing characteristic by the grinding | polishing pad ground with the different conditioning disk. (A), (B) is a figure which shows two different conditioning disks corresponding to FIG. FIG. 15 is a diagram showing polishing characteristics on a polishing pad ground with two different conditioning disks shown in FIG. 14. 3 is a flowchart illustrating a chemical mechanical polishing process according to the first embodiment of the present invention. It is a figure which shows the grinding | polishing characteristic of Cu film | membrane by 1st Example of this invention. (A)-(E) are figures which show the manufacturing process of the semiconductor device by 2nd Example of this invention. (A)-(C) is a flowchart which shows the chemical mechanical polishing process by the 3rd Example of this invention, and the chemical mechanical polishing process by a comparative example. It is a figure explaining the evaluation method of polish in the 3rd example of the present invention. It is a figure which shows the evaluation result of grinding | polishing in 3rd Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 CMP apparatus 11 Platen 12 Polishing pad 13 Substrate carrier 14 Substrate 15 Conditioning disk 15A Washer 15B Alloy layer 15C Abrasive grain 16 Abrasive agent 21 Insulating film 21G Wiring groove 22 Barrier metal 23 Cu film 23G Cu pattern

Claims (10)

A method of manufacturing a semiconductor device including a substrate polishing step,
The polishing step includes
Chemical mechanical polishing the substrate with a polishing agent on a polishing pad;
Conditioning the surface of the polishing pad;
Including
The method of manufacturing a semiconductor device, wherein the conditioning step includes a step of grinding the surface of the polishing pad with at least first and second conditioning disks having different surface states.   The first and second conditioning disks form first and second surface roughnesses on the polishing pad surface, respectively, and the first surface roughness is larger than the second surface roughness. The method of manufacturing a semiconductor device according to claim 1.   The first and second conditioning disks are configured to grind the pad surface at first and second grinding speeds, and the first grinding speed is greater than the second grinding speed. Item 3. A method for manufacturing a semiconductor device according to Item 1 or 2.   The surface of the polishing pad is ground each time the second conditioning disk polishes the substrate, and the surface of the polishing pad is intermittently ground by the first conditioning disk. The manufacturing method of the semiconductor device as described in any one of 1-3.   5. The method of manufacturing a semiconductor device according to claim 4, wherein the first conditioning disk grinds the surface of the polishing pad simultaneously with the second conditioning disk.   The method of manufacturing a semiconductor device according to claim 1, wherein the first and second conditioning disks grind the surface of the polishing pad alternately.   The method of manufacturing a semiconductor device according to claim 1, wherein the second conditioning disk grinds the surface of the polishing pad simultaneously with the chemical mechanical polishing step of the object. .   The method for manufacturing a semiconductor device according to claim 1, wherein the polishing pad is a non-foaming type polishing pad.   The method for manufacturing a semiconductor device according to claim 1, wherein the polishing agent contains abrasive grains at a concentration of 10 wt% or less. Chemical mechanical polishing of the object on the polishing pad using an abrasive;
Conditioning the surface of the polishing pad, and a polishing method comprising:
The conditioning method includes a step of grinding the surface of the polishing pad with at least first and second conditioning disks having different surface states.

Images