JP5381672B2 - Inspection method of semiconductor device - Google Patents

Description

  The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for manufacturing a semiconductor device for polishing a film to be polished.

  Conventionally, a LOCOS (LOCal Oxidation of Silicon) method is widely known as a technique for forming an element isolation region that defines an element region.

  However, when the element isolation region is formed by the LOCOS method, the element region is reduced by the bird's beak. If the amount of oxidation in forming the element isolation region is reduced, the bird's beak can be reduced. However, if the amount of oxidation is reduced, a sufficient element isolation function cannot be obtained. In addition, when the element isolation region is formed by the LOCOS method, a large step is formed on the substrate surface. For this reason, it has been difficult to achieve further miniaturization and higher integration with the technique of forming the element isolation region using the LOCOS method.

  An STI (Shallow Trench Isolation) method has attracted attention as an alternative to the LOCOS method. A method for forming an element isolation region by the STI method will be described with reference to FIG. FIG. 47 is a process sectional view showing a conventional method for manufacturing a semiconductor device.

  First, as shown in FIG. 47A, a silicon oxide film 212 and a silicon nitride film 214 are sequentially formed on a semiconductor substrate 210.

  Next, the silicon nitride film 214 and the silicon oxide film 212 are patterned using a photolithography technique. As a result, an opening 216 reaching the semiconductor substrate 210 is formed in the silicon nitride film 214 and the silicon oxide film 212.

  Next, the semiconductor substrate 210 is anisotropically etched using the silicon nitride film 214 in which the opening 216 is formed as a mask. Thus, a trench 218, that is, a groove is formed in the semiconductor substrate 210.

  Next, as shown in FIG. 47B, a silicon oxide film 220 is formed in the trench 218 and on the silicon nitride film 214. The silicon oxide film 220 is a film to be polished.

Next, as shown in FIG. 47C, the surface of the film to be polished 220 is polished by CMP (Chemical Mechanical Polishing) until the surface of the silicon nitride film 214 is exposed. The silicon nitride film 214 functions as a stopper when the film to be polished 220 is polished. As the abrasive, for example, an abrasive containing abrasive grains made of silica and an additive made of KOH is used. Thus, the element isolation region 221 made of the silicon oxide film 220 is buried in the trench 218. An element region 222 is defined by the element isolation region 221.

  Thereafter, the silicon nitride film 214 and the silicon oxide film 212 are removed by etching. Thereafter, a transistor (not shown) is formed in the element region 222. Thus, the semiconductor device is manufactured.

  If the element isolation region 221 is formed using the STI method, a bird's beak does not occur as in the case where the element isolation region is formed by the LOCOS method, and the element region 222 can be prevented from becoming narrow. . Further, by setting the depth of the trench 218 deep, the effective inter-element distance can be increased, so that a high element isolation function can be obtained.

  However, in the conventional method for manufacturing a semiconductor device using the above-described abrasive, that is, an abrasive containing abrasive grains made of silica and an additive made of KOH, the polishing rate is not so fast, Good flatness was not obtained.

Recently, a polishing agent including a polishing abrasive and an additive composed of a surfactant has been proposed as a polishing agent having a high polishing rate and good flatness. In the proposed abrasive, for example, cerium oxide (ceria, CeO ₂ ) is used as abrasive grains. As the additive, for example, polyacrylic acid ammonium salt is used.

  FIG. 48 is a conceptual diagram showing a polishing mechanism when a film to be polished is polished using a proposed polishing agent. FIG. 49 is a process sectional view showing a case where a film to be polished is polished by using the proposed method for manufacturing a semiconductor device.

  FIG. 48A and FIG. 49A show a state before the surface of the film to be polished is polished.

  As shown in FIGS. 48A and 49A, the surface of the film to be polished 220 has irregularities. In the state where the surface of the film 220 to be polished is uneven, the additive 224 made of a surfactant adheres to the recess, and therefore the polishing of the film 220 to be polished is inhibited in the recess. On the other hand, since a high pressure is applied to the convex portion, the additive 224 made of a surfactant is peeled off and the polishing of the polishing target film 220 is not hindered. For this reason, the convex portions existing on the surface of the film to be polished 220 are selectively polished by the polishing abrasive grains 226. Thus, the surface of the film to be polished 220 is planarized. Note that polishing for flattening the surface of the film to be polished is referred to as main polishing.

  FIG. 48B shows a state after the surface of the film to be polished is flattened.

  As shown in FIG. 48B, in the state where the surface of the film to be polished 220 is flattened, the additive 224 made of a surfactant is attached to the entire surface of the film to be polished. Is hindered, and the polishing rate becomes extremely slow. For this reason, as shown in FIG. 49B, the polishing target film 220 remains on the stopper film 214.

  Here, it is also conceivable to set the film thickness of the film to be polished 220 so that the height of the surface of the concave portion of the film to be polished 220 is substantially equal to the height of the surface of the stopper film. However, the film thickness of the film to be polished 220 generally varies by about ± 30 nm with respect to the design value. For this reason, when the film to be polished 220 is formed thicker than the design value, the film to be polished remains on the stopper film.

  If the polishing target film 220 remains on the stopper film 214, the stopper film 214 and the silicon oxide film 212 cannot be removed by etching. Therefore, the polishing target film 220 on the stopper film 214 must be removed by some method. Don't be.

  As a method for removing the film to be polished 220 remaining on the stopper film 214, it has been proposed to further polish the film to be polished 220 while stopping the supply of the abrasive and supplying pure water.

  FIG. 48 (c) shows a state in which the polishing film is further polished while supplying the polishing agent on the polishing pad and water is supplied onto the polishing pad, that is, a state in which final polishing is performed. Is shown.

  When the final polishing is started, the polishing agent used in the main polishing remains between the silicon oxide film 220 as the film to be polished and the polishing pad 228. Since the additive 224 contained in the abrasive is water-soluble, it is removed in a short time when pure water is supplied. On the other hand, the abrasive grains 226 contained in the polishing agent are not water-soluble and thus are difficult to remove, and remain between the film to be polished 220 and the polishing pad 228. As described above, the additive 224 contributes to reducing the polishing rate for the polishing target film 220 when the surface of the polishing target film 220 is planarized. While such an additive 224 is removed in a short time, the polishing abrasive grains 226 that contribute to polishing remain between the polishing target film 220 and the polishing pad 228, so that the remaining polishing abrasive grains 226 cause the polishing target film to be polished. 220 can be further polished.

  When such final polishing is performed for a predetermined time, the film to be polished 220 remaining on the stopper film 214 can be removed from the stopper film 214.

  Thus, the polishing of the film to be polished 220 is completed.

  By the way, after the polishing of the film to be polished 220 is completed, it is inspected whether or not the polishing of the film to be polished 220 has been normally performed.

  FIG. 50 is a plan view and a cross-sectional view showing an inspection pattern made of a stopper film formed on a scribe line. FIG. 50A is a plan view. FIG. 50B is a cross-sectional view taken along the line AA ′ of FIG.

  51A and 51B are a plan view and a cross-sectional view showing an inspection pattern made of a buried insulating film formed on a scribe line. FIG. 51A is a plan view. FIG. 51B is a cross-sectional view taken along line AA ′ in FIG.

  Specifically, it is inspected that the polishing target film 220 does not remain on the inspection pattern 232 a formed on the scribe line 230. Further, it is inspected whether or not the thickness of the embedded insulating film 220 embedded in the inspection trench 218a is within a predetermined inspection standard range. As a result of the inspection, if it is determined that the polishing of the polishing target film 220 has been performed normally, the process proceeds to the next step. If it is determined that the polishing of the polishing target film 220 has not been performed normally, it is treated as a defective product.

Japanese Patent Laid-Open No. 2001-9702 JP 2001-85373 A JP 2001-338902 A JP 2002-83787 A Japanese Patent Laid-Open No. 11-104955 JP 2000-248263 A

However, in the proposed method for manufacturing a semiconductor device, there is a case where a large variation occurs in the depth of a recess called dishing 223 generated on the surface of the buried oxide film 220 (see FIG. 52). FIG. 52 is a cross-sectional view showing a state in which dishing has occurred on the surface of the buried oxide film.

  Further, in the proposed method for manufacturing a semiconductor device, dishing 223 may be deeply formed on the surface of the buried oxide film 220 or the film to be polished 220 may remain on the element region 222.

  In addition, when the polishing target film 220 is polished using the proposed polishing agent, the depth of the dishing 223 varies greatly depending on the areas of the trenches 218 and 218a. FIG. 53 is a graph comparing the thickness of the buried oxide film embedded in the 40 μm × 40 μm trench and the thickness of the buried oxide film embedded in the 100 μm × 100 μm trench. As can be seen from FIG. 53, when the area of the trench is large, deep dishing 223 is generated in the buried oxide film 220, and the film thickness of the buried oxide film 220 is reduced. For this reason, when the polishing target film 220 is polished using the proposed polishing agent, it is difficult to accurately inspect whether the polishing of the polishing target film 220 has been performed normally.

  An object of the present invention is to provide a method of manufacturing a semiconductor device that can suppress variation in the thickness distribution of a buried oxide film.

  Another object of the present invention is to provide a method of manufacturing a semiconductor device capable of suppressing the occurrence of deep dishing and preventing the film to be polished from remaining on the element region.

  Still another object of the present invention is to provide a semiconductor device manufacturing method capable of accurately inspecting whether or not polishing of a film to be polished has been performed normally even when the proposed polishing agent is used. Is to provide.

According to one aspect of the present invention, a plurality of grooves including a first inspection groove and a second inspection groove having a larger area than the first inspection groove are formed in a semiconductor substrate or an insulating film. a step, so as to fill the trench, and forming a film to be polished, and while supplying a polishing agent onto the polishing pad, Ru Ken Migakusu with a polishing pad to a surface of the film to be polished step second consisting pre Symbol first the polished film embedded in the second inspection in the groove and the thickness of the first test pattern formed of the polished film buried in the inspected groove And a step of inspecting whether or not the difference between the film thickness of the inspection pattern satisfies a predetermined inspection standard, and a semiconductor device inspection method.

  As described above, according to the present invention, at the time of final polishing, not only pure water but also an abrasive is supplied onto the polishing pad, and a position for supplying the abrasive and a position for supplying pure water are appropriately set. In addition, since the ratio between the supply amount of the polishing agent and the supply amount of pure water is appropriately set, it is possible to make the in-plane distribution of the film thickness of the film to be polished after finish polishing uniform.

  In addition, according to the present invention, since the end point of finish polishing is detected based on the driving current of the polishing table or the like, the end point of finish polishing can be detected accurately. For this reason, according to the present invention, it is possible to prevent the film to be polished from remaining on the element region or the occurrence of deep dishing on the surface of the buried insulating film made of the film to be polished.

According to the present invention, the film to be polished is polished at a relatively high polishing pressure in the first stage of main polishing, and the film to be polished is polished at a relatively low polishing pressure in the second stage of main polishing. In the first stage polishing, the film to be polished is polished at a relatively high polishing pressure, so that the film to be polished can be polished at a relatively high polishing rate. On the other hand, in the polishing of the second stage, for polishing the film at a relatively low There polishing pressure, it is possible to sufficiently flatten the surface of the film to be polished. Therefore, according to the present invention, the main polishing time can be shortened without impairing the flatness of the film to be polished.

  In addition, according to the present invention, a plurality of inspection patterns having different areas are formed, and polishing on the film to be polished is normally performed based on the difference in film thickness of the embedded insulating films constituting these inspection patterns. In order to inspect whether or not the polishing was performed, even when final polishing was performed using an abrasive containing abrasive grains and an additive comprising a surfactant, polishing of the film to be polished was performed normally. It is possible to accurately inspect whether or not it has been broken. Therefore, according to the present invention, the reliability of the semiconductor device can be further improved.

  Further, according to the present invention, the finish polishing is performed with the additive attached to the surface of the film to be polished in order to remove the additive attached to the surface of the film to be polished before performing the final polishing. Can be prevented. For this reason, according to the present embodiment, it is possible to reliably prevent the film to be polished from remaining above the element region, and as a result, to reliably remove the silicon nitride film and the silicon oxide film on the element region. be able to.

It is a top view which shows a grinding | polishing apparatus. FIG. 2 is a side view showing a part of the polishing apparatus shown in FIG. 1. It is a top view which shows a part of polishing apparatus shown in FIG. FIG. 2 is an enlarged side view showing a part of the polishing apparatus shown in FIG. 1. It is the graph (the 1) which shows notionally the density | concentration of an abrasive grain, the density | concentration of an additive, and the change of polishing rate. It is the graph (the 2) which shows notionally the density | concentration of an abrasive grain, the density | concentration of an additive, and the change of polishing rate. It is a graph which shows the grinding | polishing rate with respect to a to-be-polished film. It is a graph which shows the grinding | polishing speed | rate of the to-be-polished film at the time of changing suitably the position which supplies an abrasive | polishing agent, and the position which supplies pure water. It is the conceptual diagram which shows the position which supplies an abrasive | polishing agent, and the position which supplies a pure water (the 1). It is a conceptual diagram (the 2) which shows the position which supplies an abrasive | polishing agent, and the position which supplies pure water. It is the graph (the 1) which shows the in-plane distribution of the polishing rate with respect to a to-be-polished film in the case of changing the position which supplies an abrasive | polishing agent, and the position which supplies pure water suitably. It is a graph (the 2) which shows the in-plane distribution of the grinding | polishing rate with respect to a to-be-polished film when the position which supplies an abrasive | polishing agent and the position which supplies pure water are changed suitably. It is a conceptual diagram (the 3) which shows the position which supplies an abrasive | polishing agent, and the position which supplies pure water. It is a conceptual diagram (the 4) which shows the position which supplies an abrasive | polishing agent, and the position which supplies pure water. It is a graph which shows the grinding | polishing speed | rate with respect to a to-be-polished film when changing the ratio of the supply amount of an abrasive | polishing agent, and the supply amount of pure water. It is a graph (the 1) which shows the in-plane distribution of the grinding | polishing rate with respect to a to-be-polished film when changing the ratio of the supply amount of an abrasive | polishing agent, and the supply amount of pure water. It is a graph (the 2) which shows the in- plane distribution of the polishing rate with respect to a to-be-polished film when changing the ratio of the supply amount of an abrasive | polishing agent, and the supply amount of pure water. It is a graph which shows the film thickness distribution of a to-be-polished film. It is a graph which shows the dispersion | variation in the wafer surface of the film thickness of a to-be-polished film. It is a conceptual diagram which shows in-plane distribution of the film thickness of the to-be-polished film before performing main grinding | polishing. It is process sectional drawing (the 1) which shows the manufacturing method of the semiconductor device by 1st Embodiment of this invention. FIG. 9 is a process cross-sectional view (part 2) illustrating the method for manufacturing the semiconductor device according to the first embodiment of the invention; It is process sectional drawing (the 3) which shows the manufacturing method of the semiconductor device by 1st Embodiment of this invention. It is process sectional drawing (the 1) which shows the manufacturing method of the semiconductor device by the modification of 1st Embodiment of this invention. It is process sectional drawing (the 2) which shows the manufacturing method of the semiconductor device by the modification of 1st Embodiment of this invention. It is a graph which shows the change of the drive current of a grinding | polishing table. It is a graph which shows the change of the level | step difference which exists on the surface of a to-be-polished film. It is a graph which shows the relationship between the grinding | polishing pressure in the case of main grinding | polishing, and grinding | polishing time. It is a graph which shows the level | step difference which remain | survives on the surface of a to-be-polished film when performing main grinding | polishing. It is a graph which shows the level | step difference which remains in a chip | tip area | region when main polishing is performed. It is a graph which shows the change of the film thickness of the to-be-polished film | membrane which remain | survives on an element area | region. It is a graph which shows the result of having processed the dispersion | variation in the amount of dishing between wafers statistically. It is process sectional drawing (the 1) which shows the manufacturing method of the semiconductor device by 2nd Embodiment of this invention. It is process sectional drawing (the 2) which shows the manufacturing method of the semiconductor device by 2nd Embodiment of this invention. It is process sectional drawing (the 3) which shows the manufacturing method of the semiconductor device by 2nd Embodiment of this invention. It is a top view which shows the manufacturing method of the semiconductor device by 3rd Embodiment of this invention. It is a graph which shows the relationship between the area of a 2nd test pattern, and the film thickness difference of the film thickness of a 1st test pattern, and a 2nd test pattern. It is process sectional drawing which shows the manufacturing method of the semiconductor device by the modification (the 1) of 3rd Embodiment of this invention. It is process sectional drawing which shows the manufacturing method of the semiconductor device by the modification (the 2) of 3rd Embodiment of this invention. It is process sectional drawing which shows the manufacturing method of the semiconductor device by the modification (the 3) of 3rd Embodiment of this invention. It is a side view which shows the grinding | polishing apparatus used with the manufacturing method of the semiconductor device by 4th Embodiment of this invention. It is process sectional drawing (the 1) which shows the manufacturing method of the semiconductor device by 4th Embodiment of this invention. It is process sectional drawing (the 2) which shows the manufacturing method of the semiconductor device by 4th Embodiment of this invention. It is process sectional drawing (the 3) which shows the manufacturing method of the semiconductor device by 4th Embodiment of this invention. It is a graph which shows the supply amount of an abrasive | polishing agent, and the supply amount of pure water. It is the top view and sectional drawing which show the manufacturing method of the semiconductor device by the deformation | transformation embodiment of this invention. It is process sectional drawing which shows the manufacturing method of the conventional semiconductor device. It is a conceptual diagram which shows the mechanism of grinding | polishing at the time of grind | polishing a to-be-polished film | membrane using the proposed abrasive | polishing agent. It is process sectional drawing which shows the case where a to-be-polished film is grind | polished using the manufacturing method of the proposed semiconductor device. It is the top view and sectional drawing which show the pattern for a test | inspection which consists of the stopper film | membrane formed in the scribe line. It is the top view and sectional drawing which show the pattern for a test | inspection which consists of the embedded insulating film formed in the scribe line. It is sectional drawing which shows the state which dishing produced on the surface of the buried oxide film. 6 is a graph comparing the thicknesses of buried oxide films buried in trenches. It is process sectional drawing (the 1) which shows the mechanism in which a to-be-polished film remains above an element area | region. It is process sectional drawing (the 2) which shows the mechanism in which a to-be-polished film remains above an element area | region. It is process sectional drawing (the 3) which shows the mechanism in which a to-be-polished film remains above an element area | region.

[First Embodiment]
Prior to describing the semiconductor device manufacturing method according to the present embodiment, the polishing apparatus used in the present embodiment will be described with reference to FIGS. FIG. 1 is a plan view showing a polishing apparatus. FIG. 2 is a side view showing a part of the polishing apparatus shown in FIG. FIG. 3 is a plan view showing a part of the polishing apparatus shown in FIG. FIG. 4 is an enlarged side view showing a part of the polishing apparatus shown in FIG.

  As shown in FIG. 1, three rotatable polishing tables 102 a to 102 c are provided on the base 100.

  In the present embodiment, the surface of the film to be polished is polished using, for example, the polishing table 102a. Note that the surface of the film to be polished may be polished using the polishing tables 102b and 102c.

  As shown in FIG. 2, a polishing pad 104 is provided on each of the polishing tables 102a to 102c. As the polishing pad 104, for example, a polishing pad (model number: IC1400) manufactured by Rodel Nitta Co., Ltd. is used.

  On the base 100, a carousel 110 having arms 108a to 108d is provided.

  The arms 108a to 108d are respectively provided with rotatable polishing heads 112a to 112d. By appropriately rotating the carousel 110, the polishing heads 112a to 112d can be moved.

  As shown in FIG. 2, the polishing heads 112 a to 112 d support the semiconductor substrate 10. The polishing heads 112 a to 112 d press the semiconductor substrate 10 against the polishing pad 104 while rotating the semiconductor substrate 10.

  A plurality of nozzles 124a and 124b are provided on the polishing tables 102a to 102c, respectively. The nozzle 124 a is for supplying an abrasive onto the polishing pad 104. The nozzle 124 b is for supplying pure water onto the polishing pad 104. As shown in FIG. 3, the nozzles 124 a and 124 b can individually move in the radial direction of the polishing table 102. For this reason, the position for supplying the abrasive and the position for supplying the pure water can be set individually as appropriate.

  As shown in FIG. 1, sharpening devices 114 a to 114 c for sharpening the polishing pad 104 are provided on the sides of the polishing tables 102 a to 102 c, respectively.

As shown in FIG. 4, the sharpening device 114 has a diamond disk 116. The diamond disk 116 is configured by fixing a granular diamond 120 of, for example, about 150 μm to a base metal 118 made of, for example, stainless steel. About several diamonds 120 are arranged per 1 cm ² . The diamond 120 is fixed to the base metal 118 by, for example, a nickel plating layer 122.

  Thus, the polishing apparatus used in this embodiment is configured.

  In the proposed method for manufacturing a semiconductor device, during the final polishing, the surface of the film to be polished is further polished while stopping supplying the polishing agent onto the polishing pad and supplying pure water onto the polishing pad. Was.

  FIG. 5 is a graph conceptually showing changes in the concentration of polishing abrasive grains, the concentration of additives, and the polishing rate when performing final polishing in the proposed method for manufacturing a semiconductor device. The dotted line indicates the concentration of the abrasive grains. The alternate long and short dash line indicates the concentration of the additive composed of the surfactant. The solid line indicates the polishing rate. The horizontal axis indicates time. The vertical axis indicates the concentration of polishing abrasive grains, the concentration of additives, and the polishing rate.

  When the final polishing is started, the polishing agent used in the main polishing remains between the silicon oxide film that is the film to be polished and the polishing pad. Since the additive contained in the abrasive is water-soluble, when pure water is supplied, the additive is removed in a short time. For this reason, the concentration of the additive rapidly decreases.

  On the other hand, since the abrasive grains contained in the abrasive are not water-soluble, they are difficult to remove. The additive contributes to reducing the polishing rate of the film to be polished when the surface of the film to be polished is flattened. The additive that hinders the polishing rate is removed in a short time, but the abrasive grains that contribute to the polishing are difficult to remove, so the abrasive grains left between the film to be polished and the polishing pad cause the film to be polished. It is possible to further polish the surface. The abrasive grains are gradually removed from the polishing pad by pure water supplied onto the polishing pad. For this reason, the concentration of the abrasive grains gradually decreases. As the concentration of the abrasive grains decreases, the polishing rate for the film to be polished decreases.

  FIG. 6 is a graph conceptually showing changes in the concentration of polishing abrasive grains, the concentration of additives, and the polishing rate when final polishing is performed while supplying both the polishing agent and pure water onto the polishing pad. is there. The dotted line indicates the concentration of the abrasive grains. The alternate long and short dash line indicates the concentration of the additive composed of the surfactant. The solid line indicates the polishing rate. The horizontal axis indicates time. The vertical axis indicates the concentration of polishing abrasive grains, the concentration of additives, and the polishing rate.

  As can be seen from FIG. 6, if the surface of the film to be polished is polished while supplying both the polishing agent and pure water onto the polishing pad, the concentration of polishing grains, the concentration of additives, and the polishing rate are made substantially constant. Can be held. For this reason, it becomes possible to polish the film to be polished under stable conditions.

  FIG. 7 is a graph showing the polishing rate for the film to be polished. Example 1 shows the polishing rate when the film to be polished is polished while simultaneously supplying abrasive and pure water onto the polishing pad. Comparative Example 1 shows the polishing rate when the film to be polished is polished while supplying only the polishing agent onto the polishing pad. In both Example 1 and Comparative Example 1, the film to be polished having a flat surface was polished.

  As can be seen from FIG. 7, in the case of Comparative Example 1, that is, when the film to be polished is polished while supplying only the polishing agent onto the polishing pad 104, the polishing rate is as extremely low as about 15 nm / min.

  On the other hand, in the case of Example 1, that is, when the film to be polished is polished while supplying both the polishing agent and pure water onto the polishing pad 104, the polishing rate is as extremely high as about 140 nm / min. That is, in the case of Example 1, the film to be polished can be polished at a polishing rate about 10 times that in the case of Comparative Example 1.

  From these facts, it can be seen that the surface of the film to be polished can be polished at an extremely high polishing rate by polishing the film to be polished while simultaneously supplying both the abrasive and pure water onto the polishing pad 104.

  FIG. 8 is a graph showing the polishing rate of the film to be polished when the position for supplying the polishing agent and the position for supplying pure water are appropriately changed. 9 and 10 are conceptual diagrams showing a position for supplying the abrasive and a position for supplying pure water.

Example 2, as shown in FIG. 9 (a), shows the polishing rate in the case of supplying both abrasive and pure water at a position P ₁ of the center of the polishing pad 104.

In Example 3, as shown in FIG. 9B, the polishing agent is supplied to a position P ₂ that is 12.5 cm away from the center of the polishing pad 104, and pure water is supplied to the position P ₁ at the center of the polishing pad 104. Shows the case.

In Example 4, as shown in FIG. 10A, the polishing agent is supplied to the center position P ₁ of the polishing pad 104 , and pure water is supplied to the position P ₂ that is 12.5 cm away from the center of the polishing pad 104. Shows the case.

Example 5, as shown in FIG. 10 (b), shows the case of supplying both abrasive and pure water at a position P ₂ spaced 12.5cm from the center of the polishing pad 104.

  As can be seen from FIG. 8, when the position for supplying the polishing agent and the position for supplying pure water are changed, the polishing rate changes. From this, it can be seen that the polishing rate can be controlled by appropriately setting the position for supplying the abrasive and the position for supplying the pure water.

  FIG. 11 is a graph (No. 1) showing the in-plane distribution of the polishing rate for the film to be polished when the position for supplying the polishing agent and the position for supplying pure water are appropriately changed. The horizontal axis indicates the distance from the center of the wafer. The vertical axis represents the polishing rate for the film to be polished.

Example 6, as shown in FIG. 9 (a), shows the case of supplying both abrasive and pure water at a position P ₁ of the center of the polishing pad 104.

In Example 7, as shown in FIG. 9B, the polishing agent is supplied to a position P ₂ that is 12.5 cm away from the center of the polishing pad 104, and pure water is supplied to the position P ₁ at the center of the polishing pad 104. Shows the case.

Example 8, as shown in FIG. 10 (a), an abrasive is supplied to the position _{P 1} of the center of the polishing pad 104, supplying pure water to the position _{P 2} spaced 12.5cm from the center of the polishing pad 104 Shows the case.

Example 9, as shown in FIG. 10 (b), shows the case of supplying both abrasive and pure water at a position _{P 2} spaced 12.5cm from the center of the polishing pad 104.

  As can be seen from FIG. 11, in Examples 6 and 7, the polishing rate is relatively fast in the region 5 cm or more outside the center of the wafer, and the polishing rate is relatively slow in the center of the wafer.

  In the case of Example 8, the polishing rate is relatively fast in a region 7 cm or more from the center of the wafer, and the polishing rate is relatively slow in a region 5 to 7 cm from the center of the wafer, and within 5 cm from the center of the wafer. Then, the polishing rate is relatively fast.

  In the case of Example 9, the polishing rate is relatively slow in a region 5 cm or more from the center of the wafer, and the polishing rate is relatively slow in a region 2 to 5 cm from the center of the wafer, and within 2 cm from the center of the wafer. Then, the polishing rate is relatively fast.

  From these facts, it is understood that the in-plane distribution of the polishing rate for the film to be polished can be appropriately set by appropriately setting the position for supplying the polishing agent and the position for supplying pure water.

FIG. 12 is a graph (part 2) showing the in-plane distribution of the polishing rate with respect to the film to be polished when the position for supplying the polishing agent and the position for supplying pure water are appropriately changed. The horizontal axis indicates the distance from the center of the wafer. The vertical axis represents the polishing rate for the film to be polished. In any case, the position where the polishing agent was supplied was set at a position P ₃ 6.9 cm from the center of the polishing pad 104. FIG. 13 and FIG. 14 are conceptual diagrams showing a position for supplying an abrasive and a position for supplying pure water.

Example 10 shows the case where pure water is supplied to the outside from the position where the abrasive is supplied. Specifically, as shown in FIG. 13 (a), and supplying pure water to the position _{P 4} apart 9.4cm from the center of the polishing pad 104.

Example 11 shows the case where pure water is supplied to the same position as the position where the abrasive is supplied. Specifically, as shown in FIG. 13 (b), pure water was supplied to a position P ₃ 6.9 cm away from the center of the polishing pad 104 .

Example 12 shows the case where pure water is supplied to the inner side from the position where the abrasive is supplied. Specifically, as shown in FIG. 14, pure water was supplied to a position P ₅ that was 4.4 cm away from the center of the polishing pad 104 .

  As can be seen from FIG. 12, in the cases of Examples 10 and 11, the in-plane distribution of the polishing rate for the film to be polished was relatively uniform. The reason why a relatively uniform in-plane distribution is obtained in Examples 10 and 11 is considered to be because the abrasive and pure water are mixed relatively uniformly.

  On the other hand, in the case of Example 12, the in-plane distribution of the polishing rate for the film to be polished has a relatively high polishing rate in the vicinity of the wafer center and in the vicinity of the peripheral edge, and in the region between the wafer center and the peripheral edge. The distribution was such that the speed was relatively slow. This in-plane distribution is obtained in Example 12 because the mixing of the abrasive and pure water becomes relatively nonuniform.

  Therefore, by setting the position where pure water is supplied to the same position as the position where the polishing agent is supplied or a position outside the position where the polishing agent is supplied, the in-plane distribution of the polishing rate for the film to be polished can be obtained. It can be seen that it can be set relatively uniformly.

FIG. 15 is a graph showing the polishing rate for the film to be polished when the ratio between the supply amount of the abrasive and the supply amount of pure water is changed. The position where the polishing agent is supplied is the center position P ₁ of the polishing pad 104 . The position for supplying pure water was set to a position P ₂ that was 12.5 cm from the center of the polishing pad 104 .

  In Example 13, when the supply amount of the abrasive was 0.1 liter / min and the supply amount of pure water was 0.1 liter / min, that is, the ratio between the supply amount of the abrasive and the supply amount of pure water. Is shown as 1: 1.

  In Example 14, when the supply amount of the abrasive was 0.05 liter / minute and the supply amount of pure water was 0.15 liter / minute, that is, the ratio of the supply amount of abrasive and the supply amount of pure water. Is shown as 1: 3.

  In Comparative Example 2, when the supply amount of the polishing agent was 0.2 liter / min and the supply amount of pure water was 0 liter / min, that is, polishing was performed by supplying only the polishing agent without supplying pure water. This shows the case where

  In Comparative Example 3, when the supply amount of the abrasive was 0.15 liter / minute and the supply amount of pure water was 0.05 liter / minute, that is, the ratio between the supply amount of the abrasive and the supply amount of pure water. Is 3: 1.

  As can be seen from FIG. 15, in Comparative Examples 2 and 3, that is, when the ratio of the supply amount of pure water to the supply amount of the polishing agent is relatively small, the polishing rate for the film to be polished is relatively slow.

  In contrast, in Examples 13 and 14, that is, when the ratio of the supply amount of pure water to the supply amount of the polishing agent is relatively large, the polishing rate for the film to be polished is relatively high. Specifically, in Examples 13 and 14, a polishing rate of about 5 to 10 times is obtained as compared with Comparative Examples 2 and 3.

FIG. 16 is a graph (part 1) showing the in-plane distribution of the polishing rate with respect to the polishing target film when the ratio of the supply amount of the polishing agent and the supply amount of pure water is changed. The horizontal axis indicates the distance from the center of the wafer. The vertical axis represents the polishing rate for the film to be polished. The position where the polishing agent is supplied is the center position P ₁ of the polishing pad 104 . The position for supplying pure water was set to a position P ₂ that was 12.5 cm from the center of the polishing pad 104 .

  Example 15 shows a case where the supply amount of the abrasive is 0.1 liter / minute and the supply amount of pure water is 0.1 liter / minute. That is, the ratio between the supply amount of the abrasive and the supply amount of pure water is 1: 1.

  Example 16 shows a case where the supply amount of the abrasive is 0.05 liter / minute and the supply amount of pure water is 0.15 liter / minute. That is, the ratio between the supply amount of the abrasive and the supply amount of pure water is 1: 3.

  Comparative Example 4 shows a case where the supply amount of the abrasive is 0.2 liter / minute and the supply amount of pure water is 0 liter / minute. That is, the case where only the polishing agent is supplied without supplying pure water at the time of final polishing is shown.

  Comparative Example 5 shows a case where the supply amount of the abrasive is 0.15 liter / minute and the supply amount of pure water is 0.05 liter / minute. That is, the ratio between the supply amount of the abrasive and the supply amount of pure water is 3: 1.

  As can be seen from FIG. 16, in the case of Comparative Example 4, the polishing rate is high in the region outside 9.5 cm or more from the center of the wafer, and the polishing rate is extremely low in the region within 9.5 cm from the center of the wafer.

  Further, in the case of Comparative Example 5, the polishing rate is relatively fast in a region 8.5 cm or more from the center of the wafer, and the polishing rate is extremely slow in a region within 8.5 cm from the center of the wafer.

  In the case of Example 15, the polishing rate is relatively fast in a region 7 cm or more from the center of the wafer, and the polishing rate is relatively slow in a region 5 to 7 cm from the center of the wafer, and within 5 cm from the center of the wafer. In this region, the polishing rate is relatively fast.

  In the case of Example 16, the polishing rate is relatively fast with respect to the entire surface of the wafer.

FIG. 17 is a graph (No. 2) showing the in- plane distribution of the polishing rate for the film to be polished when the ratio of the supply amount of the polishing agent and the supply amount of pure water is changed. The horizontal axis indicates the distance from the center of the wafer. The vertical axis represents the polishing rate for the film to be polished. The position for supplying the polishing agent was set to a position P3 of 6.9 cm from the center of the polishing pad 104 . The position for supplying pure water was set at a position P4 of 9.4 cm from the center of the polishing pad 104 .

  Example 17 shows a case where the ratio of the supply amount of abrasive and the supply amount of pure water was 1: 2.

  Example 18 shows a case where the ratio of the supply amount of abrasive and the supply amount of pure water was 1: 2.5.

  Example 19 shows the case where the ratio of the supply amount of abrasive and the supply amount of pure water was 1: 3.

  Example 20 shows a case where the ratio of the supply amount of abrasive and the supply amount of pure water was 1: 4.

  Example 21 shows a case where the ratio of the supply amount of abrasive and the supply amount of pure water was 1: 5.

As described above with reference to FIG. 16 , when the supply amount of pure water is 1 with respect to the supply amount of the abrasive, that is, in the case of Example 15, the in-plane distribution of the polishing rate with respect to the film to be polished is non-uniform. Met.

  On the other hand, as shown in Examples 17 to 21, when the ratio of the supply amount of pure water to the supply amount of the abrasive is 2 or more, the in-plane distribution of the polishing rate for the film to be polished is relatively uniform. Become. More specifically, when the ratio of the supply amount of pure water to the supply amount of the abrasive is about 2 to 3, as shown in Examples 17 to 19, the in-plane distribution of the polishing rate is relatively relatively small as a whole. It can be made uniform. When the ratio of the supply amount of pure water to the supply amount of the abrasive is about 4 to 5, as shown in Examples 20 and 21, the polishing rate in the region within 50 mm from the center of the wafer is slightly reduced. Distribution is obtained.

  From these facts, it is understood that the in-plane distribution of the polishing rate with respect to the film to be polished can be made uniform by setting the ratio of the supply amount of pure water to the supply amount of the abrasive to 2 or more.

  FIG. 18 shows the film thickness distribution of the film to be polished before performing polishing on the film to be polished, after performing main polishing on the film to be polished, and after performing final polishing on the film to be polished. It is a graph. The horizontal axis indicates the distance from the center of the wafer. The vertical axis represents the film thickness of the film to be polished. The broken line indicates the in-plane distribution of the film thickness of the film to be polished before the main polishing is performed on the film to be polished after the film to be polished is formed. The alternate long and short dash line indicates the in-plane distribution of the film thickness of the film to be polished before the main polishing is performed on the film to be polished and before the final polishing is performed. The solid line shows the in-plane distribution of the film thickness of the film to be polished after the final polishing is performed on the film to be polished.

  When forming the film to be polished, the film to be polished was formed under the following conditions. The film to be polished was formed on a wafer on which a step of 380 nm was formed. A silicon oxide film was formed as the film to be polished. The film formation method of the film to be polished was a CVD method. The film thickness of the film to be polished was 425 nm.

When performing main polishing on the film to be polished, the film to be polished was polished under the following conditions. That is, the supply amount of the abrasive was 0.135 liter / min. The pressure for pressing the polishing head against the polishing pad, that is, the polishing pressure was 280 gf / cm ² . The number of revolutions of the polishing head was 142 revolutions / minute. The number of revolutions of the polishing table was 140 revolutions / minute. The end point of the main polishing was detected based on the change in the driving current of the polishing table. Specifically, the end point of polishing was detected based on the change in the driving current of the polishing table being smaller than a certain value.

When performing final polishing on the film to be polished, the film to be polished was polished under the following conditions. That is, the ratio between the supply amount of the abrasive and the supply amount of pure water was 1: 5. Specifically, the supply amount of the abrasive was 0.05 liter / min. The supply amount of pure water was 0.25 liter / min. The position for supplying the abrasive was 6.9 cm away from the center of the polishing pad 104. The position where pure water was supplied was 9.4 cm away from the center of the polishing pad. The polishing pressure was 175 g weight / cm ² . The number of revolutions of the polishing head was 122 revolutions / minute. The number of revolutions of the polishing table was 120 revolutions / minute. The point of time when the silicon nitride film as the stopper film was exposed was defined as the polishing end point.

  As shown by the broken line in FIG. 18, before polishing the film to be polished, the film thickness of the film to be polished is slightly thin at the center and the peripheral part of the wafer, and the film is to be applied in the region between the center and the peripheral part of the wafer. The film thickness distribution of the polishing film was slightly thick.

  In addition, as indicated by the alternate long and short dash line, after the main polishing is performed on the film to be polished, a film in which the film to be polished is relatively thin in a region outside 80 mm from the center of the wafer. A thickness distribution was obtained.

  Further, as shown by the solid line, after the final polishing was performed on the film to be polished, a relatively uniform film thickness distribution was obtained as a whole.

  As described above, the in-plane distribution of the film thickness of the film to be polished was relatively non-uniform before and after the main film was polished on the film to be polished. After the finish polishing was performed on the film to be polished, the in-plane distribution of the film thickness of the film to be polished became relatively uniform.

  For these reasons, during finish polishing, not only pure water but also abrasive is supplied onto the polishing pad, the position for supplying the abrasive and the position for supplying pure water are appropriately set, and supply of the abrasive By appropriately setting the ratio between the amount and the supply amount of pure water, the in-plane distribution of the film thickness of the film to be polished after finish polishing can be made uniform.

  FIG. 19 shows the film of the film to be polished before performing the main polishing on the film to be polished, after performing the main polishing on the film to be polished, and after performing the final polishing on the film to be polished. It is a graph which shows the dispersion | variation in the wafer surface of thickness. When obtaining the variation of the film thickness of the film to be polished in the wafer surface, the film thickness at 40 points in the wafer was measured by an optical film thickness measuring device. Then, the difference between the measured maximum value and the minimum value of the film thickness to be polished was defined as the variation in the wafer plane.

  As shown in FIG. 19, before polishing the film to be polished, the in-plane variation of the film thickness of the film to be polished was about 32 nm.

  Further, after the main polishing was performed on the film to be polished, the in-plane variation of the film thickness of the film to be polished was about 35 nm.

  On the other hand, after the final polishing was performed on the film to be polished, the in-plane variation of the film thickness of the film to be polished was about 25 nm.

  As described above, the in-plane variation in the film thickness of the film to be polished is relatively large before the film to be polished is polished and after the main polishing is performed on the film to be polished. After finishing polishing the film, the in-plane variation in the film thickness of the film to be polished is relatively small.

  For these reasons, during finish polishing, not only pure water but also abrasive is supplied onto the polishing pad, the position for supplying the abrasive and the position for supplying pure water are appropriately set, and supply of the abrasive It can be seen that the in-plane variation in the film thickness of the film to be polished can be reduced by appropriately setting the ratio between the amount and the supply amount of pure water.

  FIG. 20 is a conceptual diagram showing the in-plane distribution of the film thickness of the film to be polished before main polishing.

  The solid line indicates that the film thickness of the film to be polished is distributed so that the film thickness of the film to be polished is slightly inside the peripheral edge of the wafer and the film thickness of the silicon oxide film is thin at the center of the wafer and the peripheral edge of the wafer. Shows the case.

  The broken line indicates that the thickness of the silicon oxide film is thick at the center of the wafer and slightly inside the peripheral edge of the wafer, and the thickness of the silicon oxide film is thin at the edge of the wafer slightly outside and the peripheral edge of the wafer. This shows a case where the film thickness of the film to be polished is distributed.

  The alternate long and short dash line indicates a case where the film thickness of the film to be polished is distributed so as to gradually increase from the peripheral edge of the wafer toward the center of the wafer.

  As shown in FIG. 20, the in-plane distribution of the film thickness of the film to be polished before the main polishing differs depending on the characteristics of the film forming apparatus and the like, and the in-plane film thickness of the film to be polished after the main polishing is performed. The distribution is greatly affected by the film thickness distribution of the film to be polished before the main polishing, but in either case, both polishing agent and pure water are supplied and polishing agent is supplied during final polishing. It is possible to make the film thickness of the film to be polished uniform by appropriately setting the position and the position for supplying pure water and appropriately setting the ratio of the supply amount of the polishing agent and the supply amount of pure water. .

(Method for manufacturing semiconductor device)
A method of manufacturing the semiconductor device according to the first embodiment of the present invention will be described with reference to FIGS. FIG. 21 is a process sectional view showing the method for manufacturing the semiconductor device according to the present embodiment.

  First, as shown in FIG. 21A, a semiconductor substrate 10 is prepared. For example, a silicon substrate is used as the semiconductor substrate 10.

  Next, a silicon oxide film 12 is formed on the entire surface of the semiconductor substrate 10 by, eg, thermal oxidation. The thickness of the silicon oxide film 12 is about 10 nm, for example.

  Next, a silicon nitride film 14 is formed on the entire surface by, eg, CVD. The film thickness of the silicon nitride film 14 is, eg, about 100 nm.

  Next, an opening 16 reaching the semiconductor substrate 10 is formed in the silicon nitride film 14 and the silicon oxide film 12 by using a photolithography technique.

  Next, the semiconductor substrate 10 is anisotropically etched using the silicon nitride film 14 in which the opening 16 is formed as a mask. Thereby, a trench 18, that is, a groove is formed in the semiconductor substrate 10. The depth of the trench 18 is, for example, about 300 nm from the surface of the silicon nitride film 14.

  Next, as shown in FIG. 21B, a silicon oxide film 20 is formed on the entire surface by, eg, high density plasma CVD. The film thickness of the silicon oxide film 20 is 450 nm, for example. Thus, the silicon oxide film 20 is buried in the trench 18. In this way, the silicon oxide film 20 having irregularities on the surface is formed. The silicon oxide film 20 is a film to be polished.

  Next, the semiconductor substrate 10 is supported by the polishing head 112a (see FIG. 1). At this time, the silicon oxide film 20 as the film to be polished is positioned on the lower surface side.

  Next, the carousel 110 is rotated about 90 degrees counterclockwise. As a result, the polishing head 112a that supports the semiconductor substrate 10 is positioned on the polishing table 102a provided with the polishing pad 104 on the upper surface.

  Next, as shown in FIG. 21C, main polishing is performed on the polishing target film 20 formed on the semiconductor substrate 10 by CMP. The main polishing is performed as follows. That is, the polishing head 112 a is lowered while rotating the semiconductor substrate 10 by the polishing head 112 a, and the surface of the polishing target film 20 is pressed against the surface of the polishing pad 104. At this time, the polishing table 102a is rotated and an abrasive is supplied onto the polishing pad 104 through the nozzle 124a.

  The polishing conditions in the main polishing are as follows.

The pressure for pressing the polishing head 112a against the polishing pad 104, that is, the polishing pressure is, for example, 100 to 500 g weight / cm ² . Here, the polishing pressure is, for example, 210 g weight / cm ² .

  The number of rotations of the polishing head 112a is, for example, 70 to 150 rotations / minute. Here, the rotation speed of the polishing head is, for example, 142 rotations / minute.

Rotational speed of the polishing table 1 0 2a is, for example, 70 to 150 revolutions / minute. Here, the rotation speed of the polishing table 102a is, for example, 140 rotations / minute.

The supply amount of the abrasive is, for example, in the range of 0.1 to 0.3 liter / min. Here, the supply amount of the abrasive is, for example, 0.15 liter / min. Abrasives, for example, supplied to the position P ₁ of the center of the polishing pad.

  As the abrasive, an abrasive containing abrasive grains and an additive composed of a surfactant is used. In such an abrasive, for example, cerium oxide (ceria) is used as abrasive grains. As an additive, for example, polyacrylic acid ammonium salt is used. As such an abrasive | polishing agent, the abrasive | polishing agent (model number: Micro Planer STI2100) by EKC Technology Co., Ltd. can be mentioned, for example.

  As described above, the main polishing end point is detected based on the change in the driving voltage or driving current of the polishing table 102a.

  The drive voltage and drive current of the polishing table 102a during main polishing change as shown in FIG. 23, for example. FIG. 23 is a graph conceptually showing changes in the driving voltage of the polishing table. The driving current of the polishing table also changes in the same manner as the driving voltage of the polishing table. When the surface of the film to be polished 20 is substantially flattened, the driving voltage and driving current of the polishing table 102a hardly change as shown in FIG. For this reason, end point detection can be performed by observing the change of the drive voltage or drive current per unit time. Specifically, the point of time when the change in the driving voltage or driving current becomes smaller than a certain value can be set as the polishing end point.

  Here, the case where the end point of main polishing is detected based on the driving voltage or driving current of the polishing table 102a has been described as an example, but the method of detecting the end point of main polishing is not limited to this. The end point of main polishing may be detected using other methods. For example, the end point may be detected by observing the torque of the polishing table 102a. In addition, the end point can be detected by observing the driving voltage, driving current, torque, and the like of the polishing head 112a.

  In this way, the planarization of the surface of the film to be polished 20 is detected by the end point detection method as described above.

  Thus, the surface of the film to be polished 20 is flattened, and the main polishing is completed (see FIG. 21C).

  The polishing pad 104 may be sharpened before the main polishing or during the main polishing.

  The conditions for sharpening the polishing pad 104 are, for example, as follows.

  The load that the diamond disk 116 applies to the polishing pad 104a is, for example, 1300 to 4600 g weight. The number of revolutions of the diamond disk 116 is, for example, 70 to 120 revolutions / minute.

Next, finish polishing is performed. Final polishing is performed as follows. That is, the abrasive is supplied onto the polishing pad 104 through the nozzle 124a, and pure water is supplied onto the polishing pad 104 through the nozzle 124b. The abrasive is supplied to the central position P1 of the polishing pad 104 . The pure water is supplied to a position P2 that is 12.5 cm away from the center of the polishing pad 104 . Then, the polishing target film 20 is pressed against the surface of the polishing pad 104 while rotating the polishing head 112a. At this time, the polishing table 102b is also rotated.

  Note that the position for supplying the abrasive and the position for supplying pure water are not limited to the above, and may be set as appropriate.

  The conditions for performing the final polishing are set as follows, for example.

The polishing pressure is, for example, in the range of 100 to 500 g weight / cm ² . Here, the polishing pressure is, for example, 210 g weight / cm ² .

  The number of rotations of the polishing head 112a is, for example, in the range of 70 to 150 rotations. Here, the number of revolutions of the polishing head is, for example, 122 revolutions / minute.

The number of rotations of the polishing table 102a is, for example, in the range of 70 to 150 rotations / minute. Here, the rotation speed of the polishing table 102a is, for example, 120 rotations / minute.

  The amount of the abrasive supplied to the polishing pad 104 is, for example, in the range of 0.05 to 0.3 liter / min. Here, the supply amount of the abrasive is, for example, 0.05 liter / min.

  The supply amount of pure water supplied onto the polishing pad 104 is, for example, in the range of 0.05 to 0.3 liter / min. Here, the supply amount of pure water is, for example, 0.15 liter / min.

  The time for final polishing is, for example, about 60 seconds.

  Note that the conditions for performing the finish polishing are not limited to the above, and may be set as appropriate.

  Thus, the silicon oxide film 20 on the silicon nitride film 14 is removed, and the finish polishing is finished (see FIG. 22A).

  Thereafter, as shown in FIG. 22B, the silicon nitride film 14 and the silicon oxide film 12 are removed by etching. An element region 22 is defined by an element isolation region 21 made of a silicon oxide film 20 embedded in the trench 18.

  Thereafter, a transistor or the like (not shown) is formed in the element region 22.

  Thus, the semiconductor device according to the present embodiment is manufactured.

  As described above, according to this embodiment, not only pure water but also a polishing agent is supplied onto the polishing pad during finish polishing, and a position for supplying the polishing agent and a position for supplying pure water are set as appropriate. In addition, since the ratio between the supply amount of the polishing agent and the supply amount of pure water is appropriately set, the in-plane distribution of the film thickness of the film to be polished after the finish polishing can be made uniform.

(Modification)
Next, a modified example of the semiconductor device manufacturing method according to the present embodiment will be explained with reference to FIGS. 24 and 25 are process cross-sectional views illustrating a method for manufacturing a semiconductor device according to this modification.

  First, as shown in FIG. 24A, an interlayer insulating film 28 is formed on a semiconductor substrate 10 on which transistors (not shown) and the like are formed.

  Next, the laminated film 30 is formed on the entire surface. The laminated film 30 is a wiring material. The stacked film 30 is formed, for example, by sequentially stacking a Ti film with a thickness of 5 nm, a TiN film with a thickness of 50 nm, an Al film with a thickness of 300 nm, a Ti film with a thickness of 5 nm, and a TiN film with a thickness of 80 nm. be able to.

  Next, as shown in FIG. 24B, the laminated film 30 is patterned using a photolithography technique. Thereby, a plurality of wirings 32 made of the laminated film 30 are formed.

  Next, as shown in FIG. 24C, a silicon oxide film 20 is formed on the entire surface by, eg, high density plasma CVD. The film thickness of the silicon oxide film 20 is about 700 nm, for example. The silicon oxide film 20 is a film to be polished.

  Next, main polishing and final polishing are performed on the polishing target film 20 made of a silicon oxide film. A method for performing main polishing and finish polishing on the film to be polished 20 may be the same as the method for manufacturing the semiconductor device described above with reference to FIGS. 21C and 22A.

  In this way, as shown in FIG. 25, a semiconductor device in which the surface of the film to be polished 20 is planarized is formed.

  Thus, the film to be polished 20 may be the film to be polished 20 formed on the wiring 32.

[Second Embodiment]
A method for fabricating a semiconductor device according to the second embodiment of the present invention will be described with reference to FIGS. 21, 22, and 26 to 32. The same components as those of the semiconductor device manufacturing method according to the first embodiment shown in FIGS. 1 to 25 are denoted by the same reference numerals, and description thereof will be omitted or simplified.

  The semiconductor device manufacturing method according to the present embodiment detects the end point of the final polishing based on the driving current of the polishing table and the like, and polishes the film to be polished with a relatively high polishing pressure when performing the main polishing. Thereafter, the main feature is that the film to be polished is polished at a relatively low polishing pressure.

  First, a semiconductor substrate 10 is prepared in the same manner as in the semiconductor device manufacturing method according to the first embodiment (see FIG. 21A).

  Next, similarly to the method for manufacturing the semiconductor device according to the first embodiment, a silicon oxide film 12 is formed on the entire surface of the semiconductor substrate 10 by, eg, thermal oxidation. The thickness of the silicon oxide film 12 is about 10 nm, for example.

  Next, as in the semiconductor device manufacturing method according to the first embodiment, a silicon nitride film 14 is formed on the entire surface by, eg, CVD. The film thickness of the silicon nitride film 14 is, eg, about 100 nm. The silicon nitride film 14 functions as a stopper film when the silicon oxide film 12 that is a film to be polished is polished.

  Next, as in the semiconductor device manufacturing method according to the first embodiment, the opening 16 reaching the semiconductor substrate 10 is formed in the silicon nitride film 14 and the silicon oxide film 12 using the photolithography technique.

  Next, as in the semiconductor device manufacturing method according to the first embodiment, the semiconductor substrate 10 is anisotropically etched using the silicon nitride film 14 having the openings 16 as a mask. Thereby, a trench 18, that is, a groove is formed in the semiconductor substrate 10. The depth of the trench 18 is, for example, about 380 nm from the surface of the silicon nitride film 14.

The next, as in the method of manufacturing the semiconductor device according to the first embodiment, the entire surface by, e.g., high-density plasma CVD method to form a silicon oxide film 20 (see FIG. 21 (b)). The film thickness of the silicon oxide film 20 is, for example, 425 nm. Thus, the silicon oxide film 20 is buried in the trench 18. In this way, the silicon oxide film 20 having irregularities on the surface is formed.

  Next, as in the semiconductor device manufacturing method according to the first embodiment, the semiconductor substrate 10 is supported by the polishing head 112a. At this time, the silicon oxide film 20 as the film to be polished is positioned on the lower surface side.

  Next, the carousel 110 is rotated about 90 degrees counterclockwise as in the semiconductor device manufacturing method according to the first embodiment. As a result, the polishing head 112a that supports the semiconductor substrate 10 is positioned on the polishing table 102a provided with the polishing pad 104 on the upper surface.

  Next, main polishing is performed on the polishing target film 20 formed on the semiconductor substrate 10 by CMP. The main polishing is performed as follows. That is, the polishing head 112 a is lowered while rotating the semiconductor substrate 10 by the polishing head 112 a, and the surface of the polishing target film 20 is pressed against the surface of the polishing pad 104. At this time, the polishing table 102a is rotated and an abrasive is supplied onto the polishing pad 104 through the nozzle 124a.

  The polishing conditions in the main polishing are as follows.

  The number of rotations of the polishing head 112a is, for example, 70 to 150 rotations / minute. Here, for example, 142 rpm.

  The number of rotations of the polishing table 112a is, for example, 70 to 150 rotations / minute. Here, for example, it is 140 rpm.

  The supply amount of the abrasive 126 is, for example, in the range of 0.1 to 0.3 liter / min. Here, for example, it is set to 0.15 liter / min.

  As the abrasive, as in the first embodiment, an abrasive containing abrasive grains and an additive composed of a surfactant is used.

  The main polishing is composed of a first stage polishing and a second stage polishing. In the first stage polishing, the surface of the film to be polished 20 is polished with a relatively high polishing pressure, and in the second stage polishing, the surface of the film to be polished 20 is polished with a relatively low polishing pressure. The reason for polishing the surface of the film to be polished 20 at a relatively high polishing pressure in the first stage polishing is to improve the throughput by polishing the surface of the film to be polished 20 at a high speed. On the other hand, the surface of the film to be polished 20 is polished at a relatively low polishing pressure in the second stage polishing because the surface of the film to be polished 20 is sufficiently polished when the surface of the film to be polished 20 is polished at a relatively low polishing pressure. This is because it can be flattened.

  The polishing conditions other than the polishing pressure may be set to be different between the first stage polishing and the second stage polishing, or may be set similarly.

The polishing pressure in the first stage polishing is, for example, 300 to 700 g weight / cm ² . Here, the polishing pressure in the first stage is set to 420 g weight / cm ² , for example.

  FIG. 26 is a graph showing changes in the driving current of the polishing table. The horizontal axis indicates time. The vertical axis represents the driving current of the polishing table.

  As shown in FIG. 26, the driving current of the polishing table 102 gradually increases and then starts to decrease. The time point A at which the drive current of the polishing table 102 starts to decrease is taken as the end point of the first stage polishing.

The polishing pressure in the second stage polishing is, for example, 60 to 300 g weight / cm ² . However, the polishing pressure in the second stage polishing is set lower than the polishing pressure in the first stage polishing. Here, the polishing pressure in the second stage is, for example, 280 g weight / cm ² .

  In the second stage polishing, polishing is performed at a lower polishing pressure than in the first stage polishing, so that the driving current of the polishing table decreases rapidly. Thereafter, the drive current of the polishing table starts to increase, and eventually the increase of the drive current of the polishing table is finished. The time point B at which the increase in the driving current of the polishing table ends is set as the end point of the second stage polishing.

  In this way, the planarization of the surface of the film to be polished 20 is detected by the end point detection method as described above.

  In this way, the surface of the silicon oxide film 20 which is a film to be polished is planarized, and the main polishing is completed (see FIG. 21C).

  The conditions for performing the main polishing are not limited to the above, and may be set as appropriate.

  Further, as in the semiconductor device manufacturing method according to the first embodiment, the polishing pad 104 may be sharpened before the main polishing or during the main polishing.

  The conditions for sharpening the polishing pad 104 are, for example, as follows.

  The load that the diamond disk 116 applies to the polishing pad 104a is, for example, 1300 to 4600 g weight. The number of revolutions of the diamond disk 116 is, for example, 70 to 120 revolutions / minute.

  Next, finish polishing is performed. Final polishing is performed as follows. That is, the abrasive is supplied onto the polishing pad 104 through the nozzle 124a, and pure water is supplied onto the polishing pad 104 through the nozzle 124b. Then, the polishing target film 20 is pressed against the surface of the polishing pad 104 while rotating the polishing head 112a. At this time, the polishing table 102b is also rotated. In addition, what is necessary is just to set the position which supplies an abrasive | polishing agent and a pure water suitably.

  The conditions for performing the final polishing are set as follows, for example.

The polishing pressure is, for example, in the range of 60 to 300 g weight / cm ² . However, in the final polishing, the film to be polished 20 is polished at a polishing pressure lower than the polishing pressure in the second stage polishing. Here, the polishing pressure is, for example, 175 g weight / cm ² .

  The supply amount of the polishing agent supplied onto the polishing pad 104 is, for example, in the range of 0.05 to 0.3 liter / min. Here, for example, 0.05 liter / min.

  The supply amount of pure water supplied onto the polishing pad 104 is, for example, in the range of 0.05 to 0.3 liter / min. Here, for example, it is set to 0.15 liter / min.

  The number of revolutions of the polishing head and the number of revolutions of the polishing table may be set differently from the first-stage polishing or the second-stage polishing, or may be set in the same manner.

  Note that the conditions for performing the finish polishing are not limited to the above, and may be set as appropriate.

  In the final polishing, since the film to be polished is polished at a lower polishing pressure than in the second stage polishing, the driving current of the polishing table decreases rapidly. Thereafter, the drive current of the polishing table starts to increase, and eventually the increase of the drive current of the polishing table is finished. Then, the driving current of the polishing table starts to decrease. In the final polishing, a point C when the driving current of the polishing table starts to decrease from the decrease to the increase is defined as the polishing end point. The point C when the driving current of the polishing table starts to decrease further from the decrease is almost coincident with the point when the surface of the silicon nitride film 14 serving as the stopper film is exposed, so that the polishing target film 20 is formed on the element region 22. It is possible to prevent deep dishing from occurring on the surface of the buried insulating film 20 while preventing the remaining of the film.

  Thus, the silicon oxide film 20 on the silicon nitride film 14 is removed, and the finish polishing is finished (see FIG. 22A).

Here, although the case of detecting based on the end point of polishing on the driving current of the polishing table 102a has been described as an example, a method of detecting the end point of the Migaku Ken is not limited to this, other methods It may be used to detect the end point of polishing. For example, the polishing end point may be detected based on the driving voltage of the polishing table 102. Further, the end point may be detected based on the driving voltage and driving current of the polishing head 112a. Since the driving voltage of the polishing table, the driving voltage of the polishing head, and the driving current of the polishing head change similarly to the driving current of the polishing table shown in FIG. 23, the end point of polishing can be detected in the same manner as described above. Is possible.

Further, the end point may be detected based on the torque of the polishing table 102a and the polishing head 112a .

  Thereafter, as shown in FIG. 22B, the silicon nitride film 14 and the silicon oxide film 12 are removed by etching. An element region 22 is defined by an element isolation region 21 made of a silicon oxide film 20 embedded in the trench 18.

  Thereafter, a transistor or the like (not shown) is formed in the element region 22.

  Thus, the semiconductor device according to the present embodiment is manufactured.

  FIG. 27 is a graph showing changes in the level difference existing on the surface of the film to be polished. In FIG. 27, the first stage polishing is performed on the film to be polished, the first stage polishing is performed on the film to be polished, and the second stage polishing is performed on the film to be polished. Later, the height of the step existing on the surface of the film to be polished 20 is shown.

  The step in the convex portion having a relatively large area is shown without hatching. Here, as the step in the convex portion having a relatively large area, the step in the convex portion of 100 μm × 100 μm was measured.

  A step in the convex portion having a relatively small area is indicated by hatching. Here, as the step in the convex portion having a relatively small area, the step due to the convex portion of 1 μm × 1 μm was measured.

  As can be seen from FIG. 27, after the first-stage polishing, the level difference in the convex portion having a relatively small area is remarkably reduced as compared to before the first-stage polishing. Specifically, after the first stage polishing, the level difference is reduced to about 12% compared to before the first stage polishing. On the other hand, the step in the convex part having a relatively large area is hardly alleviated.

  From this, it can be seen that in the first-stage polishing, the step difference in the convex portion having a relatively small area is remarkably relieved.

  In addition, after the second stage polishing, the step in the convex portion having a relatively large area is remarkably relaxed as compared to after the first stage polishing. Specifically, after the second stage polishing, the level difference is reduced to about 20% compared to after the first stage polishing.

  From this, it can be seen that, in the second stage polishing, the level difference in the convex portion having a relatively large area is remarkably relieved.

  FIG. 28 is a graph showing the relationship between the polishing pressure and the polishing time during main polishing.

In Example 22, in the semiconductor device manufacturing method according to the present embodiment, the film to be polished is polished at a relatively high polishing pressure in the first stage polishing, and at a relatively low polishing pressure in the second stage polishing. The case where the film to be polished is polished is shown. The polishing pressure in the first stage polishing was 420 g weight / cm ² . The polishing pressure in the second stage was 280 g weight / cm ² .

Comparative Example 6 shows a case where main polishing is performed at a relatively high polishing pressure without setting the polishing pressure of main polishing in two stages. The polishing pressure was 420 g weight / cm ² .

Comparative Example 7 shows the case of the proposed method for manufacturing a semiconductor device, that is, the case where main polishing is performed at a relatively low polishing pressure without setting the polishing pressure for main polishing to two stages. The polishing pressure was 280 g weight / cm ² .

  As can be seen from FIG. 28, in Comparative Example 6, the main polishing time was about 87 seconds.

  In Comparative Example 7, the main polishing time was about 138 seconds.

  In contrast, in Example 22, the main polishing time was about 110 seconds. In Example 22, as compared with Comparative Example 7, the polishing time was shortened by about 28 seconds.

  From this, it can be seen that according to the present embodiment, the time for main polishing can be shortened as compared with the proposed method for manufacturing a semiconductor device.

  FIG. 29 is a graph showing steps remaining on the surface of the film to be polished when main polishing is performed.

In Example 23, the film to be polished is polished with a relatively high polishing pressure in the first stage of the main polishing, and relatively low in the second stage of the main polishing. The case where the film to be polished is polished with pressure is shown. The polishing pressure in the first stage polishing was 420 g weight / cm ² . The polishing pressure in the second stage was 280 g weight / cm ² .

Comparative Example 8 shows a case where the main polishing is performed at a relatively high polishing pressure without setting the polishing pressure of the main polishing to two stages. The polishing pressure was 420 g weight / cm ² .

Comparative Example 9 shows the case of the proposed method for manufacturing a semiconductor device, that is, the case where main polishing is performed at a relatively low polishing pressure without setting the polishing pressure for main polishing to two stages. The polishing pressure was 280 g weight / cm ² .

  As can be seen from FIG. 29, in Comparative Example 8, the level difference remaining on the surface of the film to be polished was about 115 nm.

  In Comparative Example 9, the level difference remaining on the surface of the film to be polished was about 60 nm.

  On the other hand, in Example 23, the level difference remaining on the surface of the film to be polished was about 75 nm.

  From these facts, it can be seen that, according to the present embodiment, the step on the surface of the film to be polished 20 can be sufficiently relaxed during the main polishing, as in the proposed method for manufacturing a semiconductor device.

  FIG. 30 is a graph showing steps remaining in the chip region when main polishing is performed.

In Example 24, the film to be polished is polished at a relatively high polishing pressure in the first stage of the main polishing, and relatively low in the second stage of the main polishing. The case where the film to be polished is polished by pressure and the film to be polished is polished at a polishing pressure lower than that of the second stage polishing in the final polishing is shown. The polishing pressure in the first stage of main polishing was 420 g weight / cm ² . The polishing pressure in the second stage of the main polishing was 280 g weight / cm ² . The polishing pressure in the final polishing was 175 g weight / cm ² . When performing final polishing, both abrasive grains and pure water were supplied onto the polishing pad. The supply amount of abrasive grains was 0.05 liter / min. The supply amount of pure water was 0.15 liter / min. In the finish polishing, the time point C when the driving current of the polishing table started to decrease from the decrease to the increase was defined as the polishing end point.

Comparative Example 10 shows a case where main polishing is performed at a relatively high polishing pressure without setting the polishing pressure of main polishing to two stages. The polishing pressure was 420 g weight / cm ² .

Comparative Example 11 shows a case where the main polishing is performed at a relatively low polishing pressure without setting the polishing pressure of the main polishing to two stages in the case of the proposed method for manufacturing a semiconductor device. The polishing pressure was 280 g weight / cm ² .

  As can be seen from FIG. 30, in Comparative Example 10, the step in the chip was about 65 nm.

  In Comparative Example 11, the step in the chip was about 37 nm.

  In contrast, in Example 24, the step in the chip was about 37 nm.

  From these facts, it can be seen that according to the present embodiment, the step in the chip can be sufficiently relaxed as in the proposed method for manufacturing a semiconductor device.

  FIG. 31 is a graph showing changes in the film thickness of the film to be polished remaining on the element region. In FIG. 31, after performing the first stage polishing on the film to be polished, after performing the first stage polishing on the film to be polished, after performing the second stage polishing on the film to be polished. The film thicknesses of the film 20 to be polished remaining on the element region 22 after the final polishing is performed on the film to be polished are shown.

  As can be seen from FIG. 31, the film thickness of the polishing target film 20 remaining on the element region 22 gradually decreases. After the finish polishing is completed, the polishing target film 20 does not remain on the element region 22 at all. From this, it can be seen that the polishing target film 20 on the element region 22 can be reliably removed by detecting the end point of the final polishing based on the change in the driving current of the polishing table 102 and the like.

  FIG. 32 is a graph showing the result of statistically processing the variation in dishing amount between wafers. Example 25 shows the semiconductor device manufacturing method according to the present embodiment, that is, the case where the finish polishing end point is detected based on the change in the driving current of the polishing table. Comparative Example 12 shows a case where the finish polishing is performed for a predetermined time. In Comparative Example 12, the finish polishing time was 30 seconds. In both Example 25 and Comparative Example 12, 25 wafers were polished.

  The variation in dishing amount between wafers was determined as follows. That is, first, for the three chips in each wafer, the thickness of the buried insulating film buried in the 40 μm × 40 μm trench and the thickness of the buried insulating film buried in the 130 μm × 210 μm trench are respectively set. It was measured. When measuring the thickness of the buried insulating film, an optical film thickness measuring device was used. The dishing amount was calculated based on the difference between the film thickness of the buried insulating film buried in the 40 μm × 40 μm trench and the film thickness of the buried insulating film buried in the 130 μm × 210 μm trench. Since the dishing amount was obtained for each of the 25 wafers at three locations, in each of Example 25 and Comparative Example 12, 75 dishing amounts were obtained. Then, standard deviations were obtained based on 75 pieces of data related to the dishing amount. The ratio of the obtained standard deviation to the average film thickness was defined as variation between wafers.

  As can be seen from FIG. 32, in the comparative example 12, the variation in the dishing amount is as large as about 32%. From this, it can be seen that when the final polishing is performed for a predetermined time, the dishing depth varies greatly between wafers.

  On the other hand, in Example 25, the variation in dishing amount is as small as about 13%. From this, in the case of this embodiment, that is, when the end point of the final polishing is detected based on the change of the driving current of the polishing table, the wafer-to-wafer comparison is made as compared with the proposed semiconductor device manufacturing method. It can be seen that the variation in the amount of dishing can be suppressed to about half of the comparative example.

  From these facts, it can be seen that according to the present embodiment, the variation in dishing amount between wafers can be suppressed.

  As described above, the manufacturing method of the semiconductor device according to the present embodiment has one of main features in detecting the end point of the finish polishing based on the change in the driving current of the polishing table or the like.

  In the proposed method for manufacturing a semiconductor device, the polishing target film 20 is polished for a predetermined time during final polishing. For this reason, due to film thickness variation when the film to be polished 20 is formed, the film to be polished 20 remains on the element region 22 or deep dishing occurs in the buried insulating film 20 made of the film to be polished. There were times when I missed.

  On the other hand, according to the present embodiment, since the end point of the finish polishing is detected based on the change of the driving current of the polishing table 102 and the like corresponding to the exposure of the stopper film 14, the end point of the finish polishing is accurately detected. be able to. Therefore, according to the present embodiment, it is possible to prevent the polishing target film 20 from remaining on the element region 22 or deep dishing from occurring on the surface of the buried insulating film 20 made of the polishing target film. Can do.

  In addition, in the semiconductor device manufacturing method according to the present embodiment, the polishing target film 20 is polished at a relatively high polishing pressure in the first stage of main polishing, and the polishing target film is set at a relatively low polishing pressure in the second stage of main polishing. Polishing 20 also has the main characteristics.

  In the proposed method for manufacturing a semiconductor device, the polishing target film 20 is polished at a relatively low polishing pressure during the main polishing, so that the polishing time required for the main polishing is not necessarily short enough.

On the other hand, in the semiconductor device manufacturing method according to the present embodiment, the film to be polished 20 is polished at a relatively high polishing pressure in the first stage of main polishing, and is covered at a relatively low polishing pressure in the second stage of main polishing. The polishing film 20 is polished. In the first stage polishing, since the film to be polished 20 is polished with a relatively high polishing pressure, the film to be polished 20 can be polished at a relatively high polishing rate. On the other hand, in the polishing of the second stage, for polishing the film 20 at a relatively low There polishing pressure, it is possible to sufficiently flatten the surface of the polished film 20. Therefore, according to the present embodiment, the main polishing time can be shortened without impairing the flatness of the film to be polished.

[Third Embodiment]
A method for fabricating a semiconductor device according to the third embodiment of the present invention will be described with reference to FIGS. 33 to 35 are process cross-sectional views illustrating the method for fabricating the semiconductor device according to the present embodiment. 33 to 35, the left side of the drawing shows the inside of the chip area, and the right side of the drawing shows the scribe line area. FIG. 36 is a plan view showing the method for manufacturing the semiconductor device according to the present embodiment. The same components as those in the semiconductor device manufacturing method according to the first or second embodiment shown in FIGS. 1 to 32 are denoted by the same reference numerals, and description thereof will be omitted or simplified.

  In the semiconductor device manufacturing method according to the present embodiment, a plurality of inspection patterns having different sizes are formed in advance, and the final polishing is normal based on the difference in the thickness of the buried oxide film in these inspection patterns. The main feature is to check whether or not it has been performed.

  First, the semiconductor substrate 10 is prepared (see FIG. 33A).

  Next, a silicon oxide film 12 is formed on the entire surface of the semiconductor substrate 10 by, eg, thermal oxidation. The thickness of the silicon oxide film 12 is about 10 nm, for example.

Next, a silicon nitride film 14 is formed on the entire surface by, eg, CVD. The film thickness of the silicon nitride film 14 is, eg, about 100 nm. The silicon nitride film 14 functions as a stopper film when the silicon oxide film 20 that is a film to be polished is polished.

  Next, an opening 16 reaching the semiconductor substrate 10 is formed in the silicon nitride film 14 and the silicon oxide film 12 by using a photolithography technique. At this time, an opening 16a of 40 μm × 40 μm and an opening 16b of 70 μm × 150 μm are formed in the scribe line. The distance between the opening 16a and the opening 16b is, for example, 50 μm or more.

  Next, the semiconductor substrate 10 is anisotropically etched using the silicon nitride film 14 in which the openings 16, 16 a and 16 b are formed as a mask. Thereby, a trench 18, that is, a groove is formed in the semiconductor substrate 10. The depth of the trench 18 is, for example, about 380 nm from the surface of the silicon nitride film 14. In the scribe line, a first inspection trench 18a is formed corresponding to the opening 16a, and a second inspection trench 18b is formed corresponding to the opening 16b.

  Next, a silicon oxide film 20 is formed on the entire surface by, eg, high density plasma CVD. The film thickness of the silicon oxide film 20 is, for example, 425 nm. Thus, the silicon oxide film 20 is buried in the trench 18. In this way, the silicon oxide film 20 having irregularities on the surface is formed (see FIG. 33B).

  Next, the semiconductor substrate 10 is supported by the polishing head 112a. At this time, the polishing target film 20 made of a silicon oxide film is positioned on the lower surface side.

  Next, the carousel 110 is rotated counterclockwise by about 90 degrees as in the semiconductor device manufacturing method according to the first and second embodiments. As a result, the polishing head 112a that supports the semiconductor substrate 10 is positioned on the polishing table 102a provided with the polishing pad 104 on the upper surface.

  Next, main polishing is performed on the polishing target film 20 formed on the semiconductor substrate 10 by CMP. The main polishing is performed as follows. That is, the polishing head 112 a is lowered while rotating the semiconductor substrate 10 by the polishing head 112 a, and the surface of the polishing target film 20 is pressed against the surface of the polishing pad 104. At this time, the polishing table 102a is rotated and an abrasive is supplied onto the polishing pad 104 through the nozzle 124a.

  The polishing conditions in the main polishing are as follows.

The polishing pressure is, for example, 100 to 500 g weight / cm ² . Here, the polishing pressure is set to 200 g weight / cm ² .

The number of rotations of the polishing head 112a is, for example, 70 to 150 rotations / minute. Here, the rotation speed of the polishing head 112a is, for example, 120 rotations / minute.

Rotational speed of the polishing table 1 0 2a is, for example, 70 to 150 revolutions / minute. Here, the rotation speed of the polishing table 102a is, for example, 120 rotations / minute.

  The supply amount of the abrasive 126 is, for example, in the range of 0.1 to 0.3 liter / min. Here, the supply amount of the abrasive is, for example, 0.2 liter / min.

  As the abrasive, as in the first and second embodiments, an abrasive containing abrasive grains and an additive composed of a surfactant is used.

The end point in the main polishing is detected based on a change in the driving current of the polishing table 102a and the like, as in the first embodiment.

  Thus, the main polishing with respect to the polishing target film 20 is completed (see FIG. 34A).

  The conditions for performing the main polishing are not limited to the above, and may be set as appropriate.

  The polishing pad 104 may be sharpened before the main polishing or during the main polishing. The conditions for sharpening may be the same as those of the semiconductor device manufacturing method according to the first or second embodiment, for example.

Next, finish polishing is performed in the same manner as the semiconductor device manufacturing method according to the first embodiment. Final polishing is performed as follows. That is, the supply of the abrasive is stopped and pure water is supplied onto the polishing pad 104 through the nozzle 124b. Then, the polishing target film 20 is pressed against the surface of the polishing pad 104 while rotating the polishing head 112a. At this time, the polishing table 102b is also rotated. In addition, what is necessary is just to set the position which supplies pure water suitably. Alternatively, the surface of the polishing target film 20 may be polished while supplying both the polishing agent and pure water onto the polishing pad 104 without stopping the supply of the polishing agent.

  The conditions for performing the final polishing are set as follows, for example.

The pressure for pressing the polishing head 112a against the polishing pad 104, that is, the polishing pressure is, for example, in the range of 50 to 500 g weight / cm ² . Here, the polishing pressure is, for example, 140 g weight / cm ² .

The number of rotations of the polishing head 112a is in the range of 40 to 150 rotations / minute. Here, the rotational speed of the polishing head 112a is 120 revolutions / minute.

The number of rotations of the polishing table 102a is in the range of 40 to 150 rotations / minute. Here, the number of rotations of the polishing table 102a is 120 rotations / minute.

  The supply amount of pure water supplied onto the polishing pad 104 is, for example, in the range of 0.1 to 10 liters / minute. Here, for example, it is 0.2 liter / min.

  The time for final polishing is, for example, 40 seconds.

  Note that the conditions for performing the finish polishing are not limited to the above, and may be set as appropriate.

  Thus, the silicon oxide film 20 on the silicon nitride film 14 is removed, and the finish polishing is finished (see FIG. 34B).

  As shown in FIGS. 34 (b) and 36, the first inspection trench 18a formed in the scribe line 36 between the chip region 34 and the chip region 34 is 40 μm × 40 μm made of the buried insulating film 20. The first inspection pattern 38a is embedded. Further, a second inspection pattern 38b of 70 μm × 150 μm made of the buried insulating film 20 is buried in the second inspection trench 18b formed in the scribe line 36.

As shown in FIG. 34B, since the surface area of the first inspection pattern 38a is relatively small, only extremely shallow dishing occurs on the surface of the buried insulating film 20 constituting the first inspection pattern 38a. Therefore, the film thickness d ₁ of the buried insulating film 20 constituting the first inspection pattern 38a is made relatively thick. On the other hand, since the second inspection pattern 38b has a relatively large area, relatively deep dishing occurs on the surface of the buried insulating film 20 constituting the second inspection pattern 38b. Therefore, the film thickness d ₂ of the buried insulating film 20 constituting the second test pattern 38b is made relatively thin.

Next, to measure the thickness d ₂ of the buried insulating film 20 constituting the film thickness d ₁ and a second test pattern of the buried insulating film 20 constituting the first inspection pattern 38a. Then, the film thickness d ₁ of the buried insulating film 20 constituting the first test pattern, based on the difference Δd between the film thickness d ₂ of the buried insulating film 20 constituting the second test pattern, polished It is inspected whether the polishing on the film 20 has been normally performed. Whether or not the polishing of the film to be polished 20 has been normally performed is determined by whether or not a predetermined inspection standard set in advance is satisfied.

FIG. 37 is a graph showing the relationship between the film thickness of the first inspection pattern and the difference in film thickness between the second inspection pattern and the area of the second inspection pattern. The horizontal axis indicates the surface area of the second inspection pattern 38b. The vertical axis shows the difference Δd between the film thickness d ₂ of the buried insulating film 20 constituting the thickness d ₁ of the buried insulating film 20 constituting the first inspection pattern 38a of the second inspection pattern 38b Yes. As described above, a 40 μm × 40 μm pattern was used as the first inspection pattern 38a. The reason why such a pattern having a relatively small area is used as the first inspection pattern 38a is that the pattern having a relatively small area has a very small dishing amount, and therefore, the embedded insulating film 20 constituting the first inspection pattern 38a. This is because it is possible to make the thickness d ₁ and the thickness of the reference. For this reason, the area of the first inspection pattern is preferably 3600 μm ² or less. However, if the first inspection pattern 38a is too small, it is difficult to detect a portion where the first inspection pattern 38a is formed. Therefore, the first inspection pattern 38a is 1000 μm ² or more. Preferably there is. Therefore, the area of the first inspection pattern is preferably about 1000 to 3600 μm ² .

  The solid line indicates the case of the semiconductor device manufacturing method according to the present embodiment, that is, the case where the final polishing is performed for a predetermined time using the abrasive containing the abrasive grains and the additive made of the surfactant.

  A broken line indicates a case where the final polishing is performed for 10 seconds longer than a predetermined time using an abrasive containing abrasive grains and an additive composed of a surfactant.

When measuring the film thickness of the film 20 to be polished, a thin film measuring device (model number: ASET-F5 _X ) manufactured by KLA-Tencor Co., Ltd. was used.

As can be seen by comparing the characteristic indicated by the solid line with the characteristic indicated by the broken line, the final polishing is performed using the proposed abrasive, that is, an abrasive containing an abrasive and an additive comprising a surfactant. when performing, when the time of the finish polishing is over than a predetermined polishing time, embedding constitute the film thickness d ₁ and a second test pattern 38b of the buried insulating film 20 constituting the first inspection pattern 38a the difference Δd of the thickness _{d 2} of the insulating film 20 is increased.

When polishing of the film to be polished 20 is performed whether the test was successful, and the film thickness d ₁ of the buried insulating film 20 constituting the first inspection pattern 38a and the second inspection pattern 38b the difference [Delta] d of the thickness d ₂ of the buried insulating film 20 constituting, 'compared with the (see FIG. 37), the thickness of the difference [Delta] d and the difference in thickness [Delta] d' advance difference the obtained film thickness [Delta] d and The difference ΔD is determined based on whether or not a predetermined inspection standard is satisfied.

For example, when the area of the second inspection pattern is about 10,000 μm ² , the film thickness difference Δd ′ obtained in advance is about 7 nm. When the inspection standard stipulates that ΔD is within 2 nm is determined to be normal, the thickness d ₁ of the buried insulating film 20 in the first inspection pattern 38a and the second inspection pattern 38b If the difference Δd between the film thickness d ₂ of the buried insulating film 20 is 5~9nm it is determined that polishing of the polished film 20 was successful.

  When it is determined that the polishing of the polishing target film 20 has been performed normally, the process proceeds to the next step.

On the other hand, the difference Δd between the film thickness d ₂ of the buried insulating film 20 constituting the film thickness d ₁ and a second pattern of the buried insulating film 20 constituting the first pattern, is outside the range of the predetermined inspection standard In this case, since it is considered that the polishing of the polishing target film 20 has not been performed normally, it is treated as a defective product. For example, when the difference Δd between the film thickness d ₁ of the buried insulating film 20 in the first inspection pattern 38a and the film thickness d ₂ of the buried insulating film 20 in the second inspection pattern 38b is about 15 nm. It can be determined that the polishing time is too long for 10 seconds (see FIG. 37).

As can be seen from FIG. 37, when the area of the second inspection pattern is 10000 μm ² or more, the film thickness of the embedded insulating film constituting the first inspection pattern and the embedding constituting the second inspection pattern The difference from the film thickness of the insulating film is proportional to the area of the second inspection pattern. Therefore, by setting the area of the second inspection pattern to 10000 μm ² or more, it is possible to accurately inspect whether or not the polishing of the polishing target film has been performed normally. Therefore, the area of the second inspection pattern is preferably 10,000 μm ² or more.

  Next, the silicon nitride film and the silicon oxide film are removed by etching in the same manner as in the semiconductor device manufacturing method according to the first embodiment (see FIG. 35). An element region 22 is defined by an element isolation region 21 made of a silicon oxide film 20 embedded in the trench 18.

  Thus, the semiconductor device manufacturing method according to the present embodiment is manufactured.

  Thereafter, a transistor or the like (not shown) is formed in the element region 22.

  Although two types of test patterns having different areas are formed, more patterns having different areas may be formed.

  As described above, according to the present embodiment, a plurality of inspection patterns having different areas are formed, and polishing of the film to be polished is performed based on the difference in film thickness of the buried insulating films constituting these inspection patterns. In order to inspect whether or not the polishing is normally performed, the polishing of the film to be polished is normal even when final polishing is performed using an abrasive containing abrasive grains and an additive comprising a surfactant. It is possible to accurately inspect whether or not this was done. Therefore, according to the present embodiment, the reliability of the semiconductor device can be further improved.

(Modification (Part 1))
Next, a modification (No. 1) of the method for fabricating the semiconductor device according to the present embodiment will be explained with reference to FIG. FIG. 38 is a process cross-sectional view illustrating the method for manufacturing the semiconductor device according to the present modification.

  First, as shown in FIG. 38A, an interlayer insulating film 28 made of a silicon oxide film is formed on a semiconductor substrate 10 on which a transistor having a gate electrode (not shown) and source / drain regions 27 is formed. .

Next, contact holes 40 reaching the source / drain regions 27 are formed in the interlayer insulating film 28 by using a photolithography technique. The contact hole 40 is for embedding a conductor plug. At this time, a first inspection trench (not shown) and a second inspection trench (not shown) are formed in the scribe line 36 (see FIG. 36) .

  Next, a polysilicon film 20a is formed on the entire surface.

Next, the surface of the polishing target film 42 made of a polysilicon film is polished. The method for polishing the polishing target film 42 is the same as the method for manufacturing the semiconductor device described above with reference to FIGS. 34 (a) and 34 (b). Since the polysilicon film 20a and the silicon oxide film 28 have different polishing characteristics, when the polishing target film 20a made of a polysilicon film is polished, the interlayer insulating film 28 made of a silicon oxide film functions as a stopper film. The first test train Chi及 beauty second testing train Ji, the first test pattern (not shown) and a second test pattern (not shown) is formed.

  Thus, as shown in FIG. 38B, the conductor plug 44 made of polysilicon is embedded in the contact hole 40.

  Thus, the semiconductor device according to this modification is manufactured.

  As described above, the polishing target film 20 a may be a polysilicon film 20 a formed on the interlayer insulating film 28.

(Modification (Part 2))
Next, a modification (No. 2) of the method for fabricating the semiconductor device according to the present embodiment will be explained with reference to FIG. FIG. 39 is a process cross-sectional view illustrating the method for manufacturing the semiconductor device according to the present modification.

  First, as shown in FIG. 39A, an interlayer insulating film 28 made of a silicon oxide film is formed on a semiconductor substrate 10 on which a transistor having a gate electrode (not shown) and source / drain regions 27 is formed. To do.

  Next, contact holes 40 reaching the source / drain regions 27 are formed in the interlayer insulating film 38 by using a photolithography technique. The contact hole 40 is for embedding a conductor plug.

  Next, a TiN film 41 is formed on the entire surface. The TiN film 41 functions as a barrier film. Although the TiN film 41 is formed here, a Ti film and a TiN film may be sequentially stacked.

  Next, a tungsten film 43 is formed. The tungsten film 43 is a wiring material. Thus, the laminated film 20b made of the TiN film 41 and the tungsten film 43 is formed.

  Next, in the same manner as the semiconductor device manufacturing method described above with reference to FIGS. 34A and 34B, the surface of the polishing target film 20b made of a laminated film is polished. As a result, the conductor plug 42 a made of a laminated film is embedded in the contact hole 40.

  Thus, the semiconductor device according to this modification is manufactured.

  Thus, the film to be polished 20b may be a laminated film made of the TiN film 41, the tungsten film 43, or the like.

(Modification (Part 3))
Next, a modification (No. 3) of the method for fabricating the semiconductor device according to the present embodiment will be explained with reference to FIG. FIG. 40 is a process cross-sectional view illustrating the method for manufacturing the semiconductor device according to the present modification.

  First, as shown in FIG. 40A, an interlayer insulating film 28 made of a silicon oxide film is formed on a semiconductor substrate 10 on which transistors (not shown) and the like are formed.

  Next, a trench 40 a is formed in the interlayer insulating film 28 using a photolithography technique. The trench 40a is for embedding wiring.

  Next, a TiN film 41 is formed on the entire surface. The TiN film 41 functions as a barrier film similarly to the above. Although the TiN film 41 is formed here, a Ti film and a TiN film may be sequentially stacked.

  Next, a Cu film 44 is formed. The Cu film 44 serves as a wiring material. In this way, the laminated film 20c composed of the TiN film 41 and the Cu film 44 is formed.

  Next, in the same manner as the semiconductor device manufacturing method described above with reference to FIG. 40B, the surface of the polishing target film 20c made of a laminated film is polished. As a result, the wiring 42b is buried in the trench 40a from the laminated film.

  Thus, the semiconductor device according to this modification is manufactured.

  Thus, the film to be polished 20c may be a laminated film made of the TiN film 41, the Cu film 44, or the like.

[Fourth Embodiment]
If the final polishing is simply performed after the main polishing, the polishing target film may remain above the element region.

  54 to 56 are process cross-sectional views showing the mechanism by which the film to be polished remains above the element region.

  As shown in FIG. 54A, the semiconductor substrate 210 includes a relatively wide trench 218b and a relatively narrow trench 218c. A polished film 220 made of a silicon oxide film is formed on the semiconductor substrate 210 in which the trenches 218b and 218c are formed. Since the film to be polished 220 is formed on the semiconductor substrate 210 in which the trenches 218b and 218c are formed, the unevenness 219 is formed on the surface of the film to be polished 220. A recess 219a is present on the surface of the polishing target film 220 above the relatively wide trench 218b. On the other hand, above the element region 222, a convex portion 219 b exists on the surface of the film to be polished 220. Further, even above the relatively narrow trench 218c, the convex portion 219b is present on the surface of the polishing target film 220.

  In the main polishing, an abrasive containing abrasive grains (not shown) and an additive 224 made of a surfactant is supplied onto the polishing pad 104. The additive 224 adheres to the surface of the polishing target film 220. When polishing is started, the additive 224 on the convex portion 219b is removed by applying a large pressure, and the additive 224 selectively remains on the concave portion 219a (see FIG. 54B).

  When the surface of the film to be polished 220 is planarized, the main polishing is finished. In the region 217a where the concave portion 219a was present, a large amount of the additive 224 is adhered even when the main polishing is completed. On the other hand, in the area | region 217b where the convex part 219b existed, not much additive was adhering. That is, a large amount of additive 224 adheres to the surface of the film to be polished 220 above the relatively wide trench 218b, while above the element region 222 and above the relatively narrow trench 218c, The additive 224 is not so much adhered to the surface of the film to be polished 220 (see FIG. 55A).

  In the final polishing, an abrasive and pure water are supplied onto the polishing pad 104. In the region 217a where the concave portion 219a was present, since a large amount of the additive 224 is adhered to the surface of the film to be polished 220, final polishing is performed without the additive 224 being sufficiently removed by pure water. . On the other hand, in the region 217b where the convex portions 219b existed, the additive 224 is only slightly attached to the surface of the film to be polished 220, so that the additive 224 is sufficiently removed with pure water. Polishing is performed (see FIG. 55B).

In the region 217b where the protrusions 219b existed, the final polishing is performed in a state where the additive 224 is sufficiently removed from the surface of the polishing target film 220, so that the polishing of the polishing target film 220 is reliably performed. On the other hand, in the region 217a in which recesses 219a was present, because the final polishing is performed in a state where the additive 224 from the surface of the polished film 220 is not completely removed sufficiently, sufficient polishing for the film to be polished 22 0 Not done. Therefore, the polishing target film 220 remains above the element region 222 in the vicinity of the region 217a where the recess 219a existed (see FIG. 56).

  As a result of intensive studies, the present inventor has come up with the idea of removing the additive adhering to the surface of the film to be polished using pure water after performing main polishing and before performing final polishing.

  If the additive adhering to the surface of the film to be polished is removed before performing the final polishing, it is possible to prevent the film to be polished from being polished with the additive adhering to the surface of the film to be polished. It becomes possible to do. For this reason, it is possible to reliably polish the film to be polished even in the region where the concave portion was present.

  A method of manufacturing a semiconductor device according to the fourth embodiment of the present invention will be described with reference to FIGS. FIG. 41 is a side view showing a polishing apparatus used in the present embodiment. 42 to 44 are process cross-sectional views illustrating the method for fabricating the semiconductor device according to the present embodiment. The same components as those of the semiconductor device manufacturing method according to the first to third embodiments shown in FIGS. 1 to 40 are denoted by the same reference numerals, and description thereof will be omitted or simplified.

  First, the polishing apparatus used in this embodiment will be described with reference to FIG.

  The polishing apparatus used in the present embodiment has the same basic configuration as the polishing apparatus described above with reference to FIGS.

  The polishing apparatus according to the present embodiment differs from the polishing apparatus described above with reference to FIGS. 1 to 4 in that a nozzle 124c for injecting pure water at a high pressure is further provided in addition to the nozzles 124a and 124b. ing. Pure water is sprayed at a high pressure because a large amount of pure water is supplied onto the polishing pad 104 in a short time, and the additive 24 (see FIG. 42 (b)) adhering to the surface of the film to be polished 20 is removed in a short time. This is for sure removal.

  Thus, the polishing apparatus used in this embodiment is configured. An example of such a polishing apparatus is a chemical mechanical polishing apparatus (model number: Mirra 3400) manufactured by Applied Materials.

  Next, the method for fabricating the semiconductor device according to the present embodiment will be explained with reference to FIGS.

  First, as shown in FIG. 42A, a semiconductor substrate 10 is prepared in the same manner as the semiconductor device manufacturing method according to the first embodiment.

  Next, similarly to the method for manufacturing the semiconductor device according to the first embodiment, a silicon oxide film 12 is formed on the entire surface of the semiconductor substrate 10 by, eg, thermal oxidation.

  Next, as in the semiconductor device manufacturing method according to the first embodiment, a silicon nitride film 14 is formed on the entire surface by, eg, CVD. The silicon nitride film 14 functions as a stopper film when the silicon oxide film 12 that is a film to be polished is polished.

  Next, as in the semiconductor device manufacturing method according to the first embodiment, the opening 16 reaching the semiconductor substrate 10 is formed in the silicon nitride film 14 and the silicon oxide film 12 using the photolithography technique.

  Next, as in the semiconductor device manufacturing method according to the first embodiment, the semiconductor substrate 10 is anisotropically etched using the silicon nitride film 14 having the openings 16 as a mask. Thus, a trench (groove) 18c having a relatively wide width and a trench 18d having a relatively narrow width are formed in the semiconductor substrate 10.

The next, as in the method of manufacturing the semiconductor device according to the first embodiment, the entire surface by, e.g., high-density plasma CVD method to form a silicon oxide film 20. Thus, the silicon oxide film 20 is embedded in the trenches 18c and 18d. Since the film to be polished 20 is formed on the semiconductor substrate 10 in which the trenches 18 c and 18 d are formed, the unevenness 19 is formed on the surface of the film to be polished 20. A recess 19 a is formed on the surface of the polishing target film 20 above the relatively wide trench 18 c. On the other hand, a convex portion 19 b is formed on the surface of the polishing target film 20 above the element region 22. In addition, a convex portion 19b is formed on the surface of the polishing target film 20 even above the trench 18d having a relatively small width.

  Next, as in the semiconductor device manufacturing method according to the first embodiment, the semiconductor substrate 10 is supported by the polishing head 112a (see FIG. 41). At this time, the silicon oxide film 20 as the film to be polished is positioned on the lower surface side.

  Next, as in the semiconductor device manufacturing method according to the first embodiment, the carousel 110 (see FIG. 1) is rotated about 90 degrees counterclockwise. As a result, the polishing head 112a that supports the semiconductor substrate 10 is positioned on the polishing table 102a provided with the polishing pad 104 on the upper surface.

  Next, main polishing is performed on the polishing target film 20 formed on the semiconductor substrate 10 by CMP. The main polishing is performed as follows. That is, the polishing head 112 a is lowered while rotating the semiconductor substrate 10 by the polishing head 112 a, and the surface of the polishing target film 20 is pressed against the surface of the polishing pad 104. At this time, the polishing table 102a is rotated and an abrasive is supplied onto the polishing pad 104 through the nozzle 124a.

  The polishing conditions in the main polishing are as follows.

The pressure for pressing the polishing head 112a against the polishing pad 104, that is, the polishing pressure is, for example, 100 to 500 g weight / cm ² . Here, the polishing pressure is, for example, 280 gf / cm ² .

  The number of rotations of the polishing head 112a is, for example, 70 to 150 rotations / minute. Here, for example, it is 122 rpm.

  The number of rotations of the polishing table 112a is, for example, 70 to 150 rotations / minute. Here, for example, 120 rpm.

  The supply amount of the abrasive 126 is, for example, in the range of 0.1 to 0.3 liter / min. Here, for example, 0.135 liter / min. As the abrasive, as in the first embodiment, an abrasive containing abrasive grains and an additive composed of a surfactant is used.

  FIG. 45 is a graph showing the supply amount of abrasive and the supply amount of pure water. The horizontal axis indicates time, and the vertical axis indicates the supply amount of the abrasive or pure water. In FIG. 45, the dotted line indicates the supply amount of the abrasive, and the solid line indicates the supply amount of pure water.

  In the main polishing, an abrasive containing abrasive grains (not shown) and an additive 24 made of a surfactant is supplied onto the polishing pad 104. The additive 24 adheres to the surface of the polishing target film 20. When polishing is started, the additive 24 on the convex portion 19b is removed by applying a large pressure, and the additive 24 selectively remains on the concave portion 19a (see FIG. 42B).

  The end point detection of the main polishing may be performed based on a change in the driving voltage or driving current of the polishing table 102a, for example, as in the semiconductor device manufacturing method according to the first embodiment. Thus, it is detected that the surface of the film to be polished 20 has been planarized.

  Thus, the surface of the silicon oxide film 20 that is the film to be polished is planarized, and the main polishing is completed.

  The conditions for performing the main polishing are not limited to the above, and may be set as appropriate.

  In the region 17a where the recess 19a was present, a large amount of the additive 24 is adhered to the surface of the polishing target film 20 even when the main polishing is completed. On the other hand, in the region 17b where the convex portions 19b existed, the additive 24 is not so much adhered to the surface of the film to be polished 20. That is, a large amount of the additive 24 adheres to the surface of the film to be polished 20 above the relatively wide trench 18c, while above the element region 22 and above the relatively narrow trench 18d, The additive 24 does not adhere so much to the surface of the film to be polished 20 (see FIG. 43A).

  As in the semiconductor device manufacturing method according to the first embodiment, the polishing pad 104 may be sharpened before the main polishing or during the main polishing.

  The conditions for sharpening the polishing pad 104 are, for example, as follows.

  The load that the diamond disk 116 applies to the polishing pad 104a is, for example, 1300 to 4600 g weight. The number of revolutions of the diamond disk 116 is, for example, 70 to 120 revolutions / minute.

Next, the additive 24 adhering to the surface of the polishing target film 220 is removed using pure water (see FIG. 43B). The removal of the additive 24 is performed as follows. That is, pure water is sprayed onto the polishing pad 104 at a high pressure via the nozzle 124c, and the surface of the film to be polished 20 is pressed against the polishing pad 104 while rotating the polishing head 112a. At this time, also rotated about the polishing table 10 2.

  The conditions for removing the additive 24 are set as follows, for example.

  The supply amount of pure water is, for example, in the range of 0.2 to 10 liters / minute. Here, for example, it is 3 liters / minute.

Here, the case where only pure water is supplied onto the polishing pad 104 when the additive 24 is removed with pure water has been described as an example (see FIG. 45), but when the additive 24 is removed, An abrasive may be supplied as well as pure water. However, when the supply amount of pure water is not sufficiently large relative to the supply amount of the polishing agent, it is difficult to remove the additive 24 adhering to the surface of the film to be polished with pure water. Therefore, it is necessary that the supply amount of pure water is sufficiently larger than the supply amount of the abrasive. For example, it is desirable to set the supply amount of pure water to 5 times or more with respect to the supply amount of the abrasive. More preferably, the supply amount of pure water with respect to the supply amount of the abrasive is preferably set to 7 times or more.

The pressure which injects pure water shall be the range of 70-7000 g weight / cm < ² >, for example. Here, for example, it is 1750 g weight / cm ² .

  In addition, the pressure at the time of injecting pure water is not limited to the above. For example, pure water may be supplied onto the polishing pad 104 without applying pressure to the pure water.

  The time for removing the additive 24 is, for example, about 1 to 10 seconds. Here, for example, 4 seconds is set.

Polishing pressure is in the range of for example 100 to 500 fold / cm ^2. Here, the polishing pressure is, for example, 210 g weight / cm ² .

  The number of rotations of the polishing head 112a is, for example, in the range of 70 to 150 rotations / minute. Here, the number of revolutions of the polishing head is, for example, 122 revolutions / minute.

  The number of rotations of the polishing table 102a is, for example, in the range of 70 to 150 rotations / minute. Here, the rotation speed of the polishing table is, for example, 120 rotations / minute.

  The conditions for removing the additive 24 are not limited to the above, and may be set as appropriate.

  In this way, the additive 24 made of a surfactant attached to the surface of the film to be polished 20 is removed with pure water.

  Next, finish polishing is performed. Final polishing is performed as follows. That is, the abrasive is supplied onto the polishing pad 104 through the nozzle 124a, and pure water is supplied onto the polishing pad 104 through the nozzle 124b. Then, the polishing target film 20 is pressed against the surface of the polishing pad 104 while rotating the polishing head 112a. At this time, the polishing table 102b is also rotated.

  The conditions for performing the final polishing are set as follows, for example.

The polishing pressure is, for example, in the range of 100 to 500 g weight / cm ² . Here, the polishing pressure is, for example, 210 g weight / cm ² .

  The supply amount of the polishing agent supplied onto the polishing pad 104 is, for example, in the range of 0.05 to 0.3 liter / min. Here, for example, it is set to 0.1 liter / min.

  The supply amount of pure water supplied onto the polishing pad 104 is, for example, in the range of 0.05 to 0.3 liter / min. Here, for example, 0.25 liter / min.

  The number of rotations of the polishing head 112a is, for example, in the range of 70 to 150 rotations / minute. Here, the number of revolutions of the polishing head is, for example, 122 revolutions / minute.

  The number of rotations of the polishing table 102a is, for example, in the range of 70 to 150 rotations / minute. Here, the rotation speed of the polishing table is, for example, 120 rotations / minute.

  The time for final polishing is, for example, about 30 seconds.

  Note that the end point detection of the finish polishing may be performed based on a change in the driving voltage or driving current of the polishing table 102, for example, in the same manner as the semiconductor device manufacturing method according to the second embodiment.

  Further, the conditions for performing the finish polishing are not limited to the above, and may be set as appropriate.

  Thus, the silicon oxide film 20 on the silicon nitride film 14 is removed, and the finish polishing is finished (see FIG. 44A).

  Thereafter, as shown in FIG. 44B, the silicon nitride film 14 and the silicon oxide film 12 are removed by etching. An element region 22 is defined by an element isolation region 21 made of a silicon oxide film 20 embedded in the trench 18.

  Thereafter, a transistor or the like (not shown) is formed in the element region 22.

  Thus, the semiconductor device according to the present embodiment is manufactured.

  As described above, the method for manufacturing the semiconductor device according to the present embodiment uses pure water to add the additive 24 adhering to the surface of the film to be polished 20 after performing main polishing and before performing final polishing. The main feature is to remove.

  According to the present embodiment, the additive 24 attached to the surface of the film to be polished 20 is removed before the finish polishing, so that the additive 24 is attached to the surface of the film to be polished 20. It is possible to prevent the finish polishing from being performed. Therefore, according to the present embodiment, it is possible to reliably prevent the polishing target film 20 from remaining above the element region 22, and as a result, the silicon nitride film 14 and the silicon oxide film 12 on the element region 22. Can be reliably removed.

[Modified Embodiment]
The present invention is not limited to the above embodiment, and various modifications can be made.

  For example, in the above embodiment, the case where the polishing target film 20 is a silicon oxide film and the stopper film 14 is a silicon nitride film has been described as an example. However, the materials of the polishing target film 20 and the stopper film 14 are limited to these. It is not something. Any material having a different polishing rate can be appropriately used as the material of the polishing target film 20 and the stopper film 14. For example, the polishing target film 20 may be a silicon oxide film, and the stopper film 14 may be a silicon film.

  In the above embodiment, after forming the trench 18, the silicon oxide film 20 is formed so as to fill the trench 18. However, after forming the trench 18, as shown in FIG. Before the oxide film 20 is formed, a silicon oxide film 46 and a silicon nitride film 48 may be sequentially formed on the inner wall of the trench 18. 46A and 46B are a plan view and a cross-sectional view showing a method for manufacturing a semiconductor device according to a modified embodiment. 46 (a) is a plan view, and FIG. 46 (b) is a cross-sectional view taken along the line AA ′ of FIG. 46 (a).

  Moreover, although the said embodiment demonstrated to the example the case where the abrasive grain contained in an abrasive | polishing agent is a cerium oxide, the abrasive grain contained in an abrasive | polishing agent is not limited to a cerium oxide. Any other abrasive grain can be used. For example, silicon oxide (silica) may be used as the abrasive grains.

  In the third embodiment, the inspection patterns 38a and 38b are formed on the scribe line. However, the region for forming the inspection pattern is not limited to the scribe line. For example, it is formed in the chip region. Also good.

(Appendix 1)
The surface of the film to be polished formed on the semiconductor substrate is polished using the polishing pad while supplying the polishing agent containing the abrasive grains and the additive comprising the surfactant onto the polishing pad. Flattening the surface of the film;
And further polishing the surface of the film to be polished with the polishing pad while supplying the abrasive and water onto the polishing pad after the surface of the film to be polished has been planarized. A method of manufacturing a semiconductor device.

(Appendix 2)
In the method for manufacturing a semiconductor device according to attachment 1,
When the surface of the film to be polished is further polished, the water is supplied to a position outside the position where the polishing agent is supplied.

(Appendix 3)
In the method for manufacturing a semiconductor device according to attachment 1 or 2,
In the step of further polishing the surface of the film to be polished, a ratio of the supply amount of the water to the supply amount of the polishing agent is set to 2 or more.

(Appendix 4)
The surface of the film to be polished formed on the semiconductor substrate is polished using the polishing pad while supplying the polishing agent containing the abrasive grains and the additive comprising the surfactant onto the polishing pad. Flattening the surface of the film;
And further polishing the surface of the film to be polished using the polishing pad while supplying at least water on the polishing pad after the surface of the film to be polished has been planarized,
Wherein in the step of further polishing the surface of a film to be polished is, the Migaku Ken table or Migaku Ken head, drive current or drive voltage, based on further began to decrease in turn from decreasing to increasing, the end point of polishing A method for manufacturing a semiconductor device, comprising: detecting the semiconductor device.

(Appendix 5)
In the method for manufacturing a semiconductor device according to attachment 4,
In the step of further polishing the surface of the film to be polished, the surface of the film to be polished is polished at a polishing pressure lower than the polishing pressure in the step of planarizing the film to be polished. .

(Appendix 6)
In the method for manufacturing a semiconductor device according to attachment 5,
In the step of further polishing the surface of the film to be polished, the surface of the film to be polished is polished with a polishing pressure of 60 to 300 g weight / cm ² .

(Appendix 7)
In the method for manufacturing a semiconductor device according to any one of appendices 4 to 6,
The step of planarizing the surface of the film to be polished includes a first polishing step of polishing the surface of the film to be polished with a first polishing pressure, and a second polishing pressure lower than the first polishing pressure. And a second polishing step of polishing the surface of the film to be polished. A method for manufacturing a semiconductor device, comprising:

(Appendix 8)
In the method for manufacturing a semiconductor device according to attachment 7,
In the first polishing step, a polishing end point is detected based on a decrease in driving current or driving voltage of the polishing table or the polishing head. A method for manufacturing a semiconductor device, comprising:

(Appendix 9)
In the method for manufacturing a semiconductor device according to appendix 7 or 8,
In the second polishing step, the polishing end point is detected based on the end of the increase in driving current or driving voltage of the polishing table or the polishing head. A method for manufacturing a semiconductor device, comprising:

(Appendix 10)
In the method for manufacturing a semiconductor device according to any one of appendices 7 to 9,
In the first polishing step or the second polishing step, after detecting an end point of polishing, the surface of the film to be polished is further polished for a predetermined time.

(Appendix 11)
In the method for manufacturing a semiconductor device according to any one of appendices 1 to 10,
Before the step of planarizing the surface of the film to be polished, a step of forming an insulating film having a polishing characteristic different from that of the film to be polished on the semiconductor substrate; and a step of forming an opening in the insulating film; Etching the semiconductor substrate using the insulating film as a mask to form a groove in the semiconductor substrate; and forming the polished film in the groove and on the insulating film,
In the step of further polishing the surface of the film to be polished, the surface of the film to be polished is polished using the insulating film as a stopper.

(Appendix 12)
Forming a plurality of grooves including a first inspected groove and a second inspected groove having a larger area than the first inspected groove in a semiconductor substrate or an insulating film;
Forming a film to be polished so as to fill the groove;
Polishing the surface of the film to be polished using the polishing pad while supplying an abrasive onto the polishing pad, and planarizing the surface of the film to be polished;
A step of further polishing the surface of the film to be polished with the polishing pad while supplying at least water onto the polishing pad after the surface of the film to be polished has been planarized;
The difference between the film thickness of the film to be polished embedded in the first groove to be inspected and the film thickness of the film to be polished embedded in the second groove to be inspected is a predetermined inspection standard. And a step of inspecting whether or not the condition is satisfied.

(Appendix 13)
In the method for manufacturing a semiconductor device according to attachment 12,
The polishing agent includes polishing abrasive grains and an additive composed of a surfactant.

(Appendix 14)
In the method for manufacturing a semiconductor device according to attachment 12 or 13,
The area of the region where the first inspected groove is formed is 1000 to 3600 μm ² ,
The method of manufacturing a semiconductor device, wherein an area of the region where the second groove to be inspected is formed is 7000 μm ² or more.

(Appendix 15)
In the method for manufacturing a semiconductor device according to any one of appendices 12 to 14,
In the step of forming the plurality of grooves, the first inspection target groove and the second inspection target groove are formed on a scribe line.

(Appendix 16)
In the method for manufacturing a semiconductor device according to any one of appendices 12 to 14,
In the step of forming the plurality of grooves, the first inspected groove and the second inspected groove are formed in a chip region. A method of manufacturing a semiconductor device, wherein:

(Appendix 17)
In the method for manufacturing a semiconductor device according to any one of appendices 4 to 16,
In the step of further polishing the surface of the film to be polished, the surface of the film to be polished is polished while supplying the polishing agent onto the polishing pad.

(Appendix 18)
The surface of the film to be polished formed on the semiconductor substrate is polished using the polishing pad while supplying the polishing agent containing the abrasive grains and the additive comprising the surfactant onto the polishing pad. Flattening the surface of the film;
Removing the additive adhering to the surface of the polishing film while supplying water onto the polishing pad after the surface of the polishing film is planarized;
While feeding and water the polishing agent onto the polishing pad, a method of manufacturing a semiconductor device, wherein the a step of further polishing with a polishing pad to a surface of a film to be polished.

(Appendix 19)
In the method for manufacturing a semiconductor device according to attachment 18,
In the step of removing the additive, the additive adhering to the surface of the film to be polished is removed while supplying water of 5 times or more the supply amount of the abrasive onto the polishing pad. A method of manufacturing a semiconductor device.

(Appendix 20)
In the method for manufacturing a semiconductor device according to any one of appendices 1 to 19,
The abrasive grains are made of cerium oxide or silicon oxide,
The method for manufacturing a semiconductor device, wherein the additive is made of polyacrylic acid ammonium salt.

DESCRIPTION OF SYMBOLS 10 ... Semiconductor substrate 12 ... Silicon oxide film 14 ... Silicon nitride film 16, 16a, 16b ... Opening part 17a ... Area | region 17b where the recessed part existed ... Area 18 where the convex part existed ... Trench 18a ... 1st test | inspection Trench 18b ... Second inspection trench 18c ... Relatively wide trench 18d ... Relatively narrow trench 19a ... Recess 19b ... Convex 20 ... Silicon oxide film, polished film, buried insulating film 20a ... Polysilicon Film, film to be polished 20b ... laminated film, film to be polished 20c ... laminated film, film to be polished 21 ... element isolation region 22 ... element region 24 ... additive 27 ... source / drain region 28 ... interlayer insulating film 30 ... laminated film 32 ... wiring 34 ... chip region 36 ... scribe line 38a ... first inspection pattern 38b ... second inspection pattern 40 ... contact hole 40a ... trench 4 ... TiN films 42, 42a ... conductor plugs 42b ... wiring 43 ... tungsten film 44 ... Cu film 46 ... silicon oxide film 48 ... silicon nitride film 100 ... bases 102a-102c ... polishing table 104 ... polishing pads 108a-108d ... arm 110 ... Carousels 112a to 112d ... Polishing heads 114a to 114c ... Shaping device 116 ... Diamond disk 118 ... Base metal 120 ... Diamond 122 ... Nickel plating layers 124a, 124b, 124c ... Nozzle 210 ... Semiconductor substrate 212 ... Silicon oxide film 214 ... Silicon nitride Film 216... Opening 217 a. Region 217 b where the concave portion was present. Region 218 where the convex portion was present. Trench 218 a... Trench 218 b for inspection. Recess 2 9b ... protrusion 220 ... silicon oxide film 221 ... isolation region 222 ... device region 223 ... dishing 224 ... additive 226 ... abrasive grains 228 ... polishing pad 230 ... scribe lines 232a, 232b ... test pattern

Claims (4)

Forming a plurality of grooves including a first inspected groove and a second inspected groove having a larger area than the first inspected groove in a semiconductor substrate or an insulating film;
Forming a film to be polished so as to fill the groove;
And while supplying a polishing agent onto the polishing pad, Ru Ken Migakusu with a polishing pad to a surface of the polished film process,
Before SL first of the first test pattern formed of the polished film buried in the inspection groove film thickness and the more consisting second second the polished film buried in the inspected groove And a step of inspecting whether or not the difference between the thickness of the pattern for inspection satisfies a predetermined inspection standard, and a method for inspecting a semiconductor device. The method for inspecting a semiconductor device according to claim 1,
The area of the first inspected groove is 1000 to 3600 μm. ² And
The area of the second groove to be inspected is 10000 μm ² That's it
A method for inspecting a semiconductor device. In the inspection method of the semiconductor device according to claim 1 or 2 ,
Wherein in the plurality of steps of forming a groove, a method of inspecting a semiconductor device, which comprises forming the first inspection groove and the second inspection grooves in the scribe line area. In the inspection method of the semiconductor device according to claim 1 or 2 ,
Wherein in the plurality of steps of forming a groove, a method of inspecting a semiconductor device, which comprises forming the first inspection groove and the second inspection grooves in the chip area.

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