JP3788810B2 - Polishing equipment - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a polishing apparatus and a polishing method used for planarizing an interlayer insulating film, forming a metal plug, and forming a buried metal wiring, which are necessary for forming a multilayered metal wiring structure of an LSI.
[0002]
[Prior art]
In recent years, various fine processing techniques have been researched and developed for higher integration and higher performance of LSIs. In this research and development, a chemical mechanical polishing method (chemical mechanical polishing, hereinafter abbreviated as CMP) has attracted attention. CMP is a polishing technique in which the chemical action between the abrasive and the object to be polished and the mechanical action of the abrasive particles in the abrasive are combined, and the altered layer formed on the surface to be polished is small. Because of its high polishing rate, it has become an indispensable technique in semiconductor device manufacturing processes, particularly in planarization of interlayer insulating films, formation of metal plugs, and formation of embedded metal wiring in a multilayer wiring formation process.
[0003]
Hereinafter, a polishing apparatus and a polishing method that are currently generally used in CMP will be described. Conventionally, polishing equipment used for mirror polishing of silicon substrates can be applied to LSI processes, for example, substrate cleaning equipment, air flow control to prevent abrasive particles from scattering in the clean room A device equipped with a transport mechanism for improving throughput is used.
[0004]
FIG. 1 is a schematic view showing a polishing apparatus. In the figure, reference numeral 1 denotes a top ring which is a member to be polished. The top ring 1 is connected to a drive mechanism such as a motor (not shown), and can be moved up and down by the drive mechanism and can be rotated. The top ring 1 is provided with an air cylinder mechanism (not shown) that applies a load W to the top ring 1. On the top ring 1, an object to be polished 2 is held by an elastic member 3 such as rubber by a vacuum chuck. A polishing surface plate 4 is disposed below the top ring 1, and a polishing pad 5 having elasticity is attached to the upper surface of the polishing surface plate 4. The polishing surface plate 4 can be rotated by a drive mechanism (not shown), and a cooling mechanism for circulating cooling water is provided. Further, an abrasive supply pipe 7 for supplying the abrasive 6 onto the polishing pad 5 is installed above the polishing surface plate 4. In addition, as a material of the polishing pad 5, generally elastic nonwoven fabric, foamed polyurethane, or the like is used.
[0005]
In the polishing apparatus having the above-described configuration, the object to be polished 2 is held by the top ring 1, the top ring 1 and the polishing surface plate 4 are rotated by the drive mechanism, and the top ring 1 is lowered downward, via the elastic member 3. The object 2 is pressed against the polishing pad 5 with a constant load W. In this state, polishing is performed by supplying the polishing agent 6 onto the polishing pad 5 from the discharge portion 8 of the polishing agent supply pipe 7.
[0006]
[Problems to be solved by the invention]
However, when applying the above-described polishing apparatus and polishing method to an LSI process such as planarization of an interlayer insulating film, formation of a metal plug, formation of a buried metal wiring, etc., the in-plane uniformity and planar accuracy of the object to be polished are insufficient. is there. In addition, the time required for device management is long and inefficient.
[0007]
For example, in the top ring and polishing pad having the above-described structure, the frictional heat generated during polishing cannot be released well, and the temperature of the object to be polished rises and dishing (in the groove during the formation of the embedded metal wiring) There is a problem in that metal wiring thickness reduction and thinning (excessive cutting of the interlayer insulating film when the interlayer insulating film is planarized) occur. In particular, since CMP uses a chemical action in polishing, if the temperature of the object to be polished rises due to frictional heat, the polishing rate becomes very fast, and the occurrence of dishing and thinning becomes significant, thereby controlling the polishing process. There is a risk that you will not be able to. In particular, when a large number of objects to be polished are polished continuously, frictional heat accumulates, so that a change in polishing rate, a dishing amount, and a thinning amount increase. As described above, when dishing or thinning occurs in the polishing process, the in-plane uniformity of the object to be polished is deteriorated, resulting in variations in polishing. As a result, the yield decreases.
[0008]
On the other hand, in the polishing pad having elasticity as described above, elastic deformation may occur during polishing, and dishing or thinning may occur in the object to be polished. In addition, in the polishing pad having elasticity, the holding of the abrasive particles in the polishing agent varies, and thereby the polishing rate varies. Therefore, the in-plane uniformity of the object to be polished is deteriorated, the polishing is varied, and the yield is deteriorated.
[0009]
In recent years, it has been studied to use a polishing pad made of a relatively hard material using hard plastic or the like. However, since this elastic pad has a small elastic deformation, the thickness variation of an object to be polished cannot be allowed. The variation in the thickness distribution of the object to be polished is directly connected to the variation in the in-plane load distribution of the object to be polished, which further deteriorates the in-plane uniformity of the polishing rate. Further, since this polishing pad is relatively hard, there is a problem that the polishing particles cannot be held sufficiently and the polishing rate becomes very slow. Further, the hard plastic used for this polishing pad has a very low thermal conductivity and high hardness, which is disadvantageous in terms of heat dissipation of frictional heat and prevention of scratches on the object to be polished.
[0010]
On the other hand, since the end point in the polishing process varies depending on the state of the polishing pad, it is very difficult to detect the end point while polishing a large number of objects to be polished. Therefore, there is a problem that the polishing varies between the objects to be polished. In such a case, a method that can accurately detect the end point of the polishing process, a method that confirms the replacement time of the polishing pad, and the like are desired.
[0011]
If there is the above-mentioned problem, the polishing process for a large number of objects to be polished cannot be stabilized.
[0012]
This invention is made | formed in view of this point, and it aims at providing the grinding | polishing apparatus which stabilizes a grinding | polishing process, and the grinding | polishing method which can grind | polish stably.
[0013]
[Means and Actions for Solving the Problems]
  In the first aspect of the present invention, the polishing pad is attached.BeA polishing surface plate;Object to be polishedA polishing body holding means for holding the polishing body so that the polishing surface of the polishing pad faces the polishing pad, and the polishing surface plate and the polishing body holding means are relatively moved to move the polishing target. A polishing apparatus for performing a polishing process on a body, wherein the object holding means isA fluid supply unit and a fluid discharge unit configured to circulate a fluid to the polished body holding unit, and a seal member that prevents leakage of fluid from the polished body holding unit.A polishing apparatus is provided.
[0014]
  In the first invention,Examples of the fluid supply means and the fluid discharge means configured to circulate the fluid include a fluid supply pipe and a fluid discharge pipe that are in communication with the polished object housing portion of the polished object holding means.
[0015]
According to the first invention, the fluid supplied from the fluid supply means uniformly presses the object to be polished, so that the object to be polished can be pressed uniformly against the polishing pad. The in-plane uniformity of the body is improved. Furthermore, by circulating the fluid, the object to be polished can be cooled during polishing, and the temperature of the object to be polished can be controlled (temperature maintenance). Thereby, the polishing rate can be stabilized.
[0016]
According to a second aspect of the present invention, there is provided a polishing surface plate to which a polishing pad is attached, and an object to be polished holding means for holding the object to be polished so that the surface to be polished of the object to be polished faces the polishing pad. A polishing apparatus that performs a polishing process on the object to be polished by relatively moving the polishing surface plate and the object to be polished holding means, and a dummy object to be pressed that comes into contact with the polishing pad, Support means for supporting the dummy object to be moved relative to the polishing pad and the dummy object, and monitoring means for monitoring a load applied to the support means or a current applied to the support means. A polishing apparatus is provided.
[0017]
A second aspect of the present invention is a polishing surface plate to which a polishing pad is attached, and an object to be polished that holds the object to be polished so that the surface to be polished of the object to be polished faces the polishing pad. A polishing apparatus that moves the polishing platen and the object holding means relative to each other and polishes the object to be polished with an abrasive, and monitors the deterioration state of the polishing pad. And the temperature of the abrasive, the pH of the abrasive, the pressing force when pressing the object to be polished onto the polishing pad, or the load on the relative movement of the polishing surface plate or the object holding means. Means for monitoring, information on the polishing rate corresponding to the deterioration state of the polishing pad, the temperature of the monitored abrasive, the pH of the abrasive, and the pressure when pressing the object to be polished onto the polishing pad Pressure or the polishing surface plate Or a calculation means for performing calculation using information on a load in relative movement of the object holding means, and a control means for controlling a polishing process based on the information obtained by the calculation means. A polishing apparatus is provided.
[0018]
In the polishing apparatus of the second invention, the material of the dummy object to be polished is preferably the same type of material as the object to be polished. For example, in the case of planarization of an interlayer insulating film, SiO2 which is the same material as the interlayer insulating film as a material of the dummy polished body₂Alternatively, a polymer material such as polyimide can be used. Further, the material of the interlayer insulating film is SiO containing boron (B) or fluorine (F) as impurities.₂In this case, the same material or fused quartz can be used as the material of the dummy object to be polished. On the other hand, in the case of embedded metal wiring formation, the same material as the metal wiring material as the material of the dummy object to be polished, an alloy mainly composed of the metal, a compound or mixture of the metal wiring material and the interlayer insulating film material, or Other metal materials having substantially the same hardness as the metal wiring material can be used. The material of the dummy object to be polished does not have to be mainly composed of the material of the object to be polished, and is an appropriate material for actually detecting the deterioration of the polishing pad. What is necessary is just to associate with the monitoring value of jigs, such as a pad.
[0019]
The load and the number of rotations applied to the dummy object to be polished are selected so that the change in the condition of the polishing pad can be grasped in detail. Therefore, it is not necessary to set the load and the number of rotations applied to the polished object holding means for holding the polished object. The size of the dummy object to be polished need not be set to be the same as that of the object to be polished, and there is no particular limitation as long as the change in the condition of the polishing pad can be grasped in detail by the change in the torque and the energization current. It is desirable that the polishing pad is smaller than the object to be polished as much as possible so that the polishing pad is not deteriorated by polishing the body.
[0020]
In the second invention, monitoring of the dummy object to be polished needs to be performed at a portion where the object to be polished is actually in contact with the polishing pad. It may be constantly monitored during polishing within the moving range, or may be periodically performed when the object to be polished is replaced. This monitoring is performed with respect to a load (load) applied to the rotating means for rotating the dummy workpiece or a current supplied to the rotating means. As the rotating means for rotating while supporting the dummy object, a mechanism or the like employed for the object holding means can be used. Examples of the monitoring means for monitoring the load (load) applied to the rotating means and the current supplied to the rotating means include a load cell and a normal ammeter.
[0021]
By providing such a monitoring mechanism using a dummy object to be polished, whether the torque fluctuation of the object holding means or the polishing platen due to the deterioration of the polishing pad is caused by the actual polishing end point, or polishing. It is possible to know exactly whether or not it is caused by the deterioration of the pad, and it is possible to easily detect the polishing end point. As a result, the product yield can be improved, and the polishing pad replacement time or dressing time can be accurately determined.
[0022]
In the polishing apparatus of the second invention, the temperature of the polishing agent, the pH of the polishing agent, the pressing force when pressing the object to be polished onto the polishing pad, or the load in the rotation of the surface plate or the object holding means holding means When monitoring and ending the polishing of the object when the value exceeds a preset value, for example, a load is applied to the polishing surface plate, the driving mechanism of the object holding means, and the object holding means. Control means electrically connected to the adding mechanism is provided, and polishing is controlled based on the monitored temperature / pH, pressing force, or rotational load information of the abrasive. When controlling the polishing, the temperature between the polishing pad or the polishing agent, the pH of the polishing agent, the pressing force, or the relationship between the rotational load and the polishing rate is obtained in advance, and the value up to the polishing end point is calculated in the form of time integration. Calculate and compare this value with the temperature of the polishing pad or polishing agent, the pH of the polishing agent, the pressing force, or the time until the rotational load changes, and whether the object to be polished has been polished to the desired thickness Judging. By performing such control, an accurate polishing end point can be determined, and the yield can be improved.
[0023]
Furthermore, the above control may be performed in combination with a monitoring mechanism using a dummy object to be polished. That is, the above control may be performed in consideration of the state of deterioration of the polishing pad by obtaining in advance the relationship between the torque variation of the workpiece holding means or polishing surface plate due to the deterioration of the polishing pad and the polishing speed. In this way, stable polishing can be realized, and very accurate end point detection can be performed, and the yield of products in CMP can be improved.
[0024]
In the first and second inventions of the present invention, the polishing pad may be a so-called soft polishing pad having elasticity or a so-called hard polishing pad made of hard plastic or the like.
[0025]
According to a third aspect of the present invention, there is provided a polishing surface plate to which a polishing pad is attached, and an object to be polished holding means for holding the object to be polished so that the surface to be polished of the object to be polished faces the polishing pad. A polishing apparatus that relatively moves the polishing surface plate and the polished body holding means to perform a polishing process on the polished body, wherein the polishing pad or the polishing pad and the polishing surface are fixed. There is provided a polishing apparatus having fluid flow means for allowing a fluid to flow between a disk and a temperature of the polishing pad controlled by the fluid.
[0026]
In the third invention, examples of the fluid flow means include a fluid supply means and a fluid discharge means configured to circulate a fluid, for example, a fluid supply pipe and a fluid discharge pipe provided in the polishing pad.
[0027]
As such a polishing pad, it has an integrally molded polishing pad in which a fluid supply pipe and a fluid discharge pipe are formed by holes or grooves penetrating vertically, or a plurality of divided members having grooves, and the grooves are combined. Therefore, it is possible to use a split type polishing pad that forms a fluid supply pipe and a fluid discharge pipe.
[0028]
In the third invention, it is preferable that a member made of a material having a higher thermal conductivity than the material of the polishing pad is interposed between the polishing pad and the polishing surface plate and at least one place in the polishing pad.
[0029]
According to the third invention, by circulating a fluid in the polishing pad, the polishing pad can be cooled during polishing, and the temperature of the object to be polished can be controlled (temperature maintenance). Thereby, the polishing rate can be stabilized. In addition, by interposing a member made of a material having a higher thermal conductivity than the material of the polishing pad, the frictional heat due to polishing can be released to the polishing platen satisfactorily, suppressing dishing and stabilizing the polishing rate. Can be promoted.
[0030]
According to a fourth aspect of the present invention, there is provided a polishing surface plate to which a polishing pad is attached, and an object to be polished holding means for holding the object to be polished so that the surface to be polished of the object to be polished faces the polishing pad. A polishing apparatus that performs a polishing process on the object by moving the polishing surface plate and the object holding means relative to each other, wherein the polishing surface of the polishing pad is formed with irregularities. And a polishing apparatus characterized in that the edge portion is formed of a curved surface.
[0031]
In the fourth invention, the fact that the edge portion that comes into contact with the object to be polished is a curved surface does not need to be a completely curved surface, and does not have an acute angle part that damages the object to be polished. .
[0032]
Moreover, it is preferable that a polishing pad does not contain the impurity larger than the average particle diameter of the abrasive particle contained in an abrasive | polishing agent. This is because if the polishing pad contains impurities larger than the average particle diameter of the abrasive particles, the surface of the object to be polished will be damaged. Further, the polishing pad is preferably subjected to a metal removal treatment before polishing. This metal removal treatment is performed for removing metal pieces that cause scratches on the surface of the object to be polished, and includes, for example, treatment with a hydrochloric acid / hydrogen peroxide solution.
[0033]
In addition, the polishing pad may have a through hole, and supply a polishing agent to the polishing surface through the through hole. With such a configuration, the abrasive can be used as a cooling medium, so that the structure of the apparatus can be simplified. Further, the polishing surface of the polishing pad is a plurality of independent layers having a two-layer structure in which the polishing surface side is relatively hard (for example, hard plastic) and the non-polishing surface side is relatively soft (for example, an elastic body such as rubber). It is preferable that it is comprised from the member which did. With such a configuration, the polishing surface of the polishing pad can follow the movement of the object to be polished well, and the in-plane non-uniformity of the polishing rate can be reduced.
[0034]
According to the fourth invention, since the edge portion where the polishing surface of the polishing pad comes into contact with the object to be polished has the uneven portion which is a curved surface, the edge portion which is a curved surface is prevented from scratching the object to be polished, In addition, the abrasive particles are held by the recesses to prevent a reduction in the polishing rate.
[0035]
In the fourth invention, the polishing pad does not contain impurities larger than the average particle diameter of the abrasive particles contained in the abrasive, and the polishing pad is subjected to metal removal treatment before polishing. As a result, the object to be polished can be further prevented from being damaged.
[0036]
In the fourth invention, the polishing pad has a through-hole, and the polishing rate can be improved by having a configuration in which the abrasive is supplied to the polishing surface through the through-hole. Furthermore, because the polishing surface of the polishing pad is composed of a plurality of independent members having a two-layer structure in which the polishing surface side is relatively hard and the non-polishing surface side is relatively soft, abnormalities due to protrusions existing on the polishing surface are caused. Polishing can be suppressed and non-uniformity in the polishing rate can be reduced.
[0037]
According to a fifth aspect of the present invention, there is provided a polishing surface plate to which a polishing pad is attached, and an object holding means for holding the object to be polished so that a surface to be polished of the object to be polished faces the polishing pad. A polishing apparatus that performs a polishing process on the object to be polished by supplying an abrasive by relatively moving the polishing surface plate and the object to be polished holding means, and comprising at least the object to be polished of the object to be polished There is provided a polishing apparatus comprising: an abrasive containing means for containing the abrasive such that a polishing surface is held in a state covered with the abrasive.
[0038]
In the fifth aspect of the invention, the state where the surface to be polished of the object to be polished is coated with the abrasive means that at least the surface to be polished of the object to be polished is in the abrasive.
[0039]
According to the fifth aspect, by polishing the object to be polished in the abrasive, the polishing particles can be held on the polishing pad, and the polishing rate can be improved.
[0040]
Here, in the first to fifth inventions of the present invention, a so-called top ring rotating body or the like can be used as the object to be polished holding means. Examples of the abrasive supply means include a mechanism for transporting the abrasive from the abrasive supply tank via the abrasive supply pipe. Alternatively, a grindstone holding an abrasive can be used as a polishing surface plate. As the object to be polished, a silicon substrate, a glass substrate for TFT-LCD, a substrate made of a compound semiconductor such as GaAs, or the like can be used.
[0041]
  In the first to fifth inventions of the present invention, the polishing pad is made of a polymer material having a Young's modulus of at least 1 GPa.Preferably formed.
[0042]
Examples of such materials include hard rubbers such as urethane rubber, fluorine rubber, and chloroprene rubber; PTFE (polytetrafluoroethylene), FEP (tetrafluoroethylene-hexafluoropropylene copolymer), PFA (tetrafluoroethylene-par Fluororesins such as fluoroalkoxyethylene copolymer), ETFE (tetrafluoroethylene-ethylene copolymer), PCTFE (polychlorotrifluoroethylene), PVdF (polyvinylidene fluoride); polyvinyl chloride, PVdC (polyvinylidene chloride) , PVAC (polyvinyl acetate), PVA (polyvinyl alcohol) and other vinyl resins; polyamides; polyacetals; polyphenylene oxides; polycarbonates; ionomers; polyurethanes; Styrene, polyethylene, polyolefin resins such as polypropylene; poly-4-methylpentene; polymethacrylates; cellulose acetate or the like can be used. The resin material may be added with usual additives such as a stabilizer and a plasticizer.
[0043]
In the first to fifth inventions of the present invention, the so-called hard polishing pad is a grindstone that holds an abrasive (the abrasive particles are sintered by hardening a thermosetting resin such as a phenol resin with a binder). It may be. This is because since the Young's modulus is high, the same effect can be realized as a grindstone.
[0044]
In the first to fifth inventions of the present invention, it is preferable that the polishing pad has a groove portion that allows the object holding means to be polished. With such a configuration, it becomes possible to supply abrasive particles to the recesses of the polishing pad, and a stable polishing rate can be provided.
[0045]
In the first to fifth inventions of the present invention, the polishing is performed by relatively moving the polishing platen and the object holding means. Therefore, during the polishing process, the polishing platen and the object holding means may be moved together, or one of the polishing table and the object holding means may be fixed and only the other may be moved. In addition, when moving the polishing surface plate and / or the object holding means, it may be rotated or oscillated. In particular, when rotating, the trajectory may be a circle or an eccentric circle such as an ellipse.
[0046]
In addition, the 1st-5th invention of this invention can be implemented in combination as appropriate.
[0047]
【Example】
Embodiments of the present invention will be specifically described below with reference to the drawings. In the description of the embodiment, the description of the schematic configuration similar to that of the polishing apparatus shown in FIG. 1 is omitted.
[0048]
(Example 1)
The present embodiment is an embodiment according to the first invention of the present invention.
[0049]
FIG. 2A is a cross-sectional view showing the top ring of the polishing apparatus according to the first aspect of the present invention, and FIG. 2B is a view of the top ring of FIG. FIG. In the figure, 11 indicates a SUS top ring. The top ring 11 is mainly composed of a drive mechanism for raising and lowering the top ring, a rotating shaft part 11a connected to an air cylinder mechanism for applying a load to the top ring 11, and a holding part 11b for holding the object to be polished. The rotating shaft portion 11a and the holding portion 11b are integrally formed. A gap 12 is provided inside the holding part 11b, and communicates with a refrigerant supply pipe 13 that supplies cooling water and a cooling gas and a refrigerant discharge pipe 14 that discharges the fluid that has flowed through the top ring. The holding portion 11b is provided with a housing portion 15 for housing the object to be polished, and a communication hole 16 communicating with the gap portion 12 is formed on the bottom surface of the housing portion. As shown in FIG. 2B, the communication hole 16 surrounds the elongated hole 16a for pressing the object to be polished and extending in three directions at the center of the bottom surface of the accommodating portion 15, and the elongated hole 16a. And a plurality of circular holes 16b for circulating the refrigerant formed as described above. In addition, as shown in FIG. 3, a rubber seal ring 18 may be provided so that the refrigerant does not leak from between the accommodating portion 15 and the object to be polished 17.
[0050]
The refrigerant is circulated by connecting the top ring 21, the vacuum source 22, the temperature regulator (chiller) 23, the refrigerant pressure source 24 (pump), and the pressure regulator 25 as shown in FIG. In addition, you may connect the top ring 21, the vacuum source 22, the temperature regulator (chiller) 23, the refrigerant | coolant pressure source 24 (pump), and the pressure regulator 25 as shown in FIG. 4 (B).
[0051]
Next, a method of forming a Cu buried wiring using the polishing apparatus having the top ring will be described.
[0052]
As a sample, as shown in FIG. 5A, a silicon oxide film 32 having a thickness of 1 μm is formed on a silicon substrate 31, and the surface of the silicon oxide film 32 has a width of 0.4 to 100 μm and a depth of 0. After forming a groove 33 for wiring having a thickness of 4 μm by a normal photolithography process and a reactive ion etching process, a Cu film 34 having a thickness of 600 nm was formed by a direct current magnetron sputtering method.
[0053]
First, the accommodating portion 15 was depressurized from the refrigerant supply pipe 14 of the top ring to hold the sample as the object to be polished 17 on the top ring 11, and then the top ring 11 and the polishing surface plate were rotated with respect to each other. Next, the top ring 11 was lowered to bring the sample into contact with the polishing pad.
[0054]
Next, water whose temperature is controlled to 14 ° C. ± 1 ° C. by a temperature controller (not shown) is injected from the refrigerant supply pipe 13, and at the same time, the water flowing in the top ring is discharged from the refrigerant discharge pipe 14. Water was circulated in the order shown in (A) or FIG. Furthermore, a semiconductor wafer is 280 gf / cm by adjusting a pressure regulating valve (not shown) provided in the refrigerant discharge pipe 14.²It pressed against the polishing pad with the surface load W. At this time, since the elongated hole 16a formed in the bottom surface of the top ring accommodating portion 15 has a shape extending in three directions, the semiconductor wafer can be evenly pressed in the plane. In this way, polishing is started. At this time, water leaking from the top ring can be reduced by setting a load applied to the top ring higher than the pressure with which the water pushes up the top ring. In this polishing, the surface temperature of the semiconductor wafer can be controlled to 14 ° C. ± 3 ° C. Polishing was performed by supplying an abrasive in this state.
[0055]
The polishing pad is made of hard resin (polyvinyl chloride having a thermal conductivity of 0.08 to 0.34), and the polishing surface is provided with grooves having a depth of 1 mm and a width of 2 mm in a lattice shape. Was used. As the abrasive, a mixture of glycine / hydrogen peroxide / benzotriazole aqueous solution and colloidal silica was used. The polishing platen was provided with a mechanism for circulating the refrigerant therein, and was maintained at 14 ° C. ± 1 ° C. by circulating the refrigerant (water). A cooling mechanism was also provided so that the polishing pad could be cooled.
[0056]
As shown in FIG. 5B, the sample polished as described above was able to suppress the dishing amount of Cu at a wide concave portion having a width of 100 μm to 50 nm. On the other hand, for comparison, when the above sample was polished without circulating the coolant through the top ring, as shown in FIG. 5C, the amount of Cu dishing in a wide recess of 100 μm was 300 nm (d). .
[0057]
FIG. 6 shows the dishing amount when the sample is polished by using the polishing apparatus according to the first aspect of the present invention, the wiring width dependency and the in-plane uniformity of the polishing rate (maximum speed-minimum speed) / (maximum (Speed + minimum speed). As can be seen from FIG. 6, by controlling the temperature of the top ring, the dishing amount can be suppressed, and the in-plane uniformity of the polishing rate is improved. By controlling the temperature of the polishing pad in addition to the temperature control of the top ring, the dishing amount can be further suppressed and the in-plane uniformity of the polishing rate is improved. As described above, according to the first aspect of the present invention, stable CMP can be performed without a change in the polishing rate with time.
[0058]
In this embodiment, Cu is used as an object to be polished, but Cu containing a small amount of impurities, metals other than Cu, such as Ag, Al, W, alloys thereof, silicon oxide, B, Even when silicon oxide containing impurities such as P and F was used as an object to be polished, the same excellent effect was obtained. Moreover, the same effects as described above were obtained even when abrasive particles other than colloidal silica, such as alumina or cerium oxide, were used as the abrasive particles. Moreover, the same effect was acquired even if it used the grindstone holding the silica particle, the alumina particle, and the cerium oxide particle instead of the polishing pad.
[0059]
Further, in this embodiment, the object to be polished is directly held by the housing portion of the top ring, but the object to be polished may be held on the bottom surface of the housing portion via an elastic body. Furthermore, in the present embodiment, the object to be polished is held on the top ring using a vacuum chuck, but the object to be polished may be held by bonding using wax or the like. In the present embodiment, the refrigerant is circulated by a pump in the top ring, but a mechanism for circulating the refrigerant can be omitted by providing a temperature control mechanism in the top ring.
[0060]
Further, in this embodiment, the top ring and the polishing pad are rotated with respect to each other to perform polishing. However, as shown in FIG. 7, the object to be polished 41 is polished using a vacuum chuck 42 and having a temperature control mechanism 43. The object to be polished may be polished by holding the polishing pad with a top ring 45 fixed to the surface plate 44 and having a mechanism for circulating the coolant, and rotating and moving only the top ring 45.
[0061]
(Example 2)
Examples 2 and 3 are examples according to the second invention of the present invention.
[0062]
FIG. 8 is a schematic view showing a polishing apparatus according to the second aspect of the present invention. In the figure, 51 indicates a rotatable polishing platen. A polishing pad 52 is attached on the polishing surface plate 51. A top ring 54 that supports the object to be polished 53 is disposed above the polishing surface plate 51. A driving means 59 such as a motor for moving the top ring 54 up and down and rotating is connected to the top ring 54. The top ring 54 has a load W during polishing.₁Is added to press the object 53 to be polished onto the polishing pad 52.
[0063]
Further, a Cu lump 55 that is a dummy object to be polished is disposed on the side of the top ring 54 and above the polishing surface plate 51. A driving means 58 such as a motor for moving the Cu lump 55 up and down and rotating is connected to the Cu lump 55. The Cu lump 55 has a load W during polishing.₂Is added to press the Cu lump 55 onto the polishing pad 52. The drive means 58 includes a torque monitor 56 that can monitor the rotational torque and a current monitor 57 that can monitor the current supplied to the drive means 58. Further, an abrasive supply pipe 60 for supplying the abrasive onto the polishing pad 52 is disposed.
[0064]
In the polishing apparatus having the above-described configuration, using a Cu film having a thickness of 8000 angstroms formed by sputtering on a silicon substrate, torque fluctuation and current fluctuation according to the state of the polishing pad and Cu film are polished while polishing the Cu film. The relationship with the polishing rate was investigated in detail. The Cu film was polished under the following conditions.
[0065]
Polishing pressure: 300 g / cm²
Top ring rotation speed: 60rpm
Polishing surface plate rotation speed: 60 rpm
Polishing temperature: 25 ° C
Abrasive supply amount: 50 cc / min
As the abrasive, 0.2 g of glycine, 40 ml of hydrogen peroxide (35%), 110 ml of pure water, and 8.8 g of colloidal silica (average particle size 30 nm) were used. As the polishing pad, SUBA800 (trade name, manufactured by Rodel) was used.
[0066]
On the other hand, the Cu lump 55 has W₂As 300g / cm²The current value (torque) necessary to keep the rotational speed constant was measured. Further, as shown in FIG. 9, a Cu lump 55 is placed on the polishing pad 52 on the polishing surface plate 51._ThreeAs 300g / cm²Thus, the polishing surface plate 51 was allowed to slide substantially in the tangential direction, and the dynamic friction force acting on the Cu lump 55 during polishing was measured by the friction force monitor 61. As the Cu lump, one having a diameter of 5 cm and a thickness of 3 cm was used. The current value (torque) and dynamic friction force were used as a reference for monitoring the state of the polishing pad.
[0067]
The polishing rate of the Cu film under these polishing conditions was about 350 angstroms / minute. After polishing for 10 minutes per silicon substrate, the silicon substrate was replaced and polishing of the Cu film was continued in the same manner as described above. When a change in the polishing rate based on a change in current value (torque) and dynamic friction force due to deterioration of the polishing pad occurred, dressing with a rotating brush of the polishing pad was performed as necessary.
[0068]
FIG. 10 is a graph showing the relationship between the current value (torque) and kinetic friction force monitored for detection of deterioration of the polishing pad and the polishing rate obtained from the remaining film thickness of Cu after polishing with respect to the number of polishing times. . FIG. 11 is a graph showing the relationship between the current value (torque) obtained from these measurement results and the polishing rate of the Cu film. As can be seen from FIGS. 10 and 11, the current value (torque) and the dynamic friction force decrease due to the deterioration of the polishing pad due to the processing of the Cu film. In addition, the Cu film polishing rate decreases as the current value (torque) and dynamic friction force decrease, and the polishing rate variation of the Cu film increases as the polishing pad deteriorates.
[0069]
(Example 3)
A case will be described in which the above relationship is used for polishing a Cu film to detect the polishing end point for the Cu film. The polishing conditions for the Cu film in this example are the same as those in Example 2.
[0070]
During polishing of the Cu film, the current value (torque) and the measured value of the dynamic friction force are sampled by the computer every second, and the relationship between the current value (torque) or the dynamic friction force and the polishing speed shown in FIG. The thickness of the polished Cu film was estimated by calculating (integrating) the amount of Cu film polished within the sampling time. When this estimated value exceeded the processing target value of 4000 angstroms, polishing was stopped as a polishing end point. Thereafter, the actual processed film thickness obtained from the film thickness of the Cu film remaining on the silicon substrate was obtained and compared with the processing target value. In this case, since the polishing rate in the silicon substrate varies, it was evaluated at a specific point on the silicon substrate.
[0071]
FIG. 12 is a graph showing the relationship between the current value monitored for the detection of the deterioration of the polishing pad and the final Cu film processing thickness with respect to the number of polishing times obtained from the above results, as can be seen from FIG. By performing the above control, the Cu film can be polished with high accuracy. In addition, by performing the above control, the polishing end point can be sufficiently predicted even if a change in the polishing rate due to deterioration of the polishing pad occurs during polishing. Further, the end point can be detected with higher accuracy by using the monitoring mechanism according to the second invention in combination with another end point detection method.
[0072]
(Example 4)
Examples 4 and 5 are examples according to the third invention of the present invention.
[0073]
FIG. 13 is a schematic view showing a polishing surface plate portion of a polishing apparatus according to the third aspect of the present invention. In the figure, reference numeral 71 denotes a rotatable SUS polishing surface plate. A disc-shaped polishing pad 72 made of hard plastic (polyvinyl chloride: thermal conductivity 0.08 to 0.34) and having a diameter of about 60 cm is attached on the polishing surface plate 71. On the polishing surface of the polishing pad 72, a plurality of grooves 73 having a depth of 1 mm and a width of 2 mm are formed in a lattice shape. In addition, a coolant circulation path 74 is inserted in the polishing surface plate 71 and the polishing pad 72, and the temperature of the polishing pad (temperature maintenance) can be adjusted by circulating a coolant (fluid) such as cooling water. It has become. The object to be polished is pressed onto the polishing pad 72 by lowering the top ring holding the object to be polished against the polishing surface plate 71.
[0074]
Using the polishing apparatus having the above configuration, CMP was performed on the Cu embedded wiring. As the abrasive, a mixture of glycine, hydrogen peroxide, benzotriazole aqueous solution, and colloidal silica was used. During polishing, the polishing pad 72 and the polishing surface plate 71 were kept at 14 ° C. ± 1 ° C. by passing cooling water through the coolant circulation path 74. As a result, dishing of the Cu wiring was greatly improved as compared with a conventional polishing apparatus that only cooled the polishing surface plate as shown in FIG. 17 and did not cool the polishing pad. Specifically, as shown in FIG. 19, the dishing of the 10 μm wide wiring has been reduced to about 25 nm compared to the conventional about 150 nm.
[0075]
  The polishing apparatus according to the third invention may be configured as shown in FIGS. That is, as shown in FIG. 14, the coolant circulation path 74 may be provided at least at the interface portion between the polishing surface plate 71 and the polishing pad 72. Further, as shown in FIGS. 15 and 16, a member 75 made of a material having high thermal conductivity may be interposed between the polishing pad 72 and the polishing surface plate 71. For example, as shown in FIG. 15, the polishing pad 72 is embedded in the member 75 so that the polishing pad 72 is exposed on the surface.MayAs shown in FIG. 16, a slit reaching the polishing surface plate 71 may be provided in the polishing pad 72, and the member 75 may be fitted therein. It is desirable that at least the structure be in contact with the abrasive during polishing. Thereby, the thermal conductivity can be improved and the temperature of the polished surface can be controlled efficiently.
[0076]
In this case, the material having a high thermal conductivity may be any material having a higher thermal conductivity than the material used as the polishing pad 72, such as urethane rubber, fluororubber, Teflon, Daiflon, polyvinyl chloride, polyamide, or the like. For example, Al, Cu, Si, iron, stainless steel, graphite, amorphous carbon, alumina, quartz, glass, or the like can be used. Further, the member 75 may contain a liquid having a higher thermal conductivity than the material used as the polishing pad 72 (for example, pure water: a thermal conductivity of about 0.6), and contains such a liquid. You may comprise with an easily porous substance and sponge-like thing.
[0077]
In this embodiment, a Cu film is used as an object to be polished, but a Cu film containing a small amount of impurities, a film made of a metal other than Cu, such as Ag, Al, W, or the like, and these as a main component. Plasma CVD film, BPSG film, fluorine-added SiO film formed using TEOS gas as a raw material₂A silicon oxide film such as a film or a thermal oxide film may be used.
[0078]
Further, in this embodiment, a polishing pad made of polyvinyl chloride is used as the polishing pad 72, and polishing is performed while supplying an abrasive. If the Young's modulus is at least 1 GPa, polishing is performed. It has been found that the same effect as described above can be obtained by using a so-called grindstone instead of the pad 72. Specifically, as a polishing pad, silica particles having an average particle size of 30 nm are sintered with phenol resin (thermosetting resin) as a binder, glycine, hydrogen peroxide solution, and benzotriazole When the polishing was performed while supplying the mixed aqueous solution onto the polishing pad, the same effect as in the case of using the polishing pad made of polyvinyl chloride was obtained in suppressing dishing.
[0079]
(Example 5)
FIG. 18 is a schematic view showing a polishing platen portion of a polishing apparatus according to the third invention of the present invention. This rotatable SUS polishing surface plate 71 is provided with a portion for storing an abrasive, and a polishing surface having a plurality of grooves 73 having a depth of 1 mm and a width of 2 mm on the polishing surface on the bottom surface of the storage portion. A pad 72 is placed. The polishing pad 72 is made of hard plastic (polyvinyl chloride: thermal conductivity 0.08 to 0.34) and has a disk shape with a diameter of about 60 cm. Further, at least the polishing surface of the polishing pad 72 is provided with a Teflon coating so that the characteristics are not deteriorated by the polishing agent 78. Further, an abrasive 78 is stored in the container so that the object to be polished is immersed in the abrasive during polishing. Further, the abrasive supply pipe 76 extends to the vicinity of the polishing pad 72 of the accommodating portion, and the abrasive discharge pipe 77 extends above the center of the accommodating portion. The abrasive 78 is circulated by the abrasive supply pipe 76 and the abrasive discharge pipe 77. By lowering the top ring holding the object to be polished against the polishing surface plate 71, the object to be polished is immersed in the abrasive 78 and further pressed onto the polishing pad 72.
[0080]
Using the polishing apparatus having the above configuration, CMP was performed on the Cu embedded wiring. As the abrasive, a mixture of glycine, hydrogen peroxide, benzotriazole aqueous solution, and colloidal silica was used. During polishing, the polishing pad 72 and the polishing surface plate 71 cause the cooled polishing agent 78 to flow through the polishing agent supply pipe 76 and the polishing agent discharge pipe 77 to circulate the polishing agent 78 stored in the accommodating portion. The temperature was kept at ± 1 ° C. As a result, dishing of the Cu wiring was greatly improved as compared with a conventional polishing apparatus that only cooled the polishing surface plate as shown in FIG. 17 and did not cool the polishing pad. Specifically, the dishing of the 10 μm wide wiring is reduced to about 25 nm compared to the conventional about 150 nm.
[0081]
Further, in this embodiment, a polishing pad made of polyvinyl chloride is used as the polishing pad 72, and polishing is performed while supplying an abrasive. If the Young's modulus is at least 1 GPa, polishing is performed. It has been found that the same effect as described above can be obtained by using a so-called grindstone instead of the pad 72. Specifically, as a polishing pad, silica particles having an average particle size of 30 nm are sintered with phenol resin (thermosetting resin) as a binder, glycine, hydrogen peroxide solution, and benzotriazole When the polishing was performed while supplying the mixed aqueous solution onto the polishing pad, the same effect as in the case of using the polishing pad made of polyvinyl chloride was obtained in suppressing dishing.
[0082]
(Example 6)
Examples 6 to 10 and Comparative Examples 1 to 3 relate to the fourth invention of the present invention.
[0083]
The present embodiment relates to the unevenness of the polishing pad in the polishing surface plate portion of FIG. As shown in FIG. 20, the polishing pad 81 made of hard plastic has a plurality of grooves 84, and the polishing surface 82 and the side wall surface of the grooves 84 are connected by a curved surface, that is, constitutes the polishing surface 82. The convex part is a curved surface. Such a shape was formed by cutting using an end mill having an R shape.
[0084]
As described above, the CMP in the Cu embedded wiring was performed using the polishing apparatus provided with the polishing pad having no sharp angle portion on the polishing surface. As the abrasive, a mixture of glycine, hydrogen peroxide, benzotriazole aqueous solution, and colloidal silica was used. During polishing, the polishing pad and the polishing surface plate were kept at 14 ° C. ± 1 ° C. by passing cooling water through the refrigerant circuit. As a result, no scratches with a depth of 20 nm or more were found on the polished surface of the Cu wiring.
[0085]
In this embodiment, a polishing pad made of polyvinyl chloride is used as the polishing pad 72, and polishing is performed while supplying an abrasive. As the polishing pad, silica particles having an average particle size of 30 nm are phenol resin. Using a product obtained by hardening (thermosetting resin) as a binder and sintering it, polishing was performed while supplying a mixed aqueous solution of glycine, hydrogen peroxide, and benzotriazole onto the polishing pad. In the suppression, the same effect as that obtained when a polyvinyl chloride polishing pad was used was obtained.
[0086]
(Comparative Example 1)
In place of the polishing pad shown in FIG. 20, a CMP in Cu embedded wiring is performed in the same manner as in Example 6 except that a polishing pad made of vinyl chloride in which grooves having a rectangular cross section with a width of 1 mm and a depth of 1 mm are formed with a pitch of 1 cm is used. Went. As a result, scratches having a depth of 1 μm or more were confirmed on the polished surface of the Cu wiring.
[0087]
(Example 7)
As a polishing pad, a polishing pad made of polyvinyl chloride containing almost no impurities having a particle size of 0.7 μm or more was used, and planarization CMP was performed on a silicon oxide film formed by a plasma CVD method using TEOS gas as a raw material. As the abrasive, an aqueous solution containing 1% by weight of cerium oxide particles having an average particle diameter of 0.7 μm was used. As a result, no scratches having a depth or width of 0.1 μm or more were found on the silicon oxide film.
[0088]
In this embodiment, a polishing pad made of polyvinyl chloride is used as the polishing pad 72 and polishing is performed while supplying an abrasive. As the polishing pad, cerium oxide particles having an average particle diameter of 600 nm are used as phenol. When a resin (thermosetting resin) is hardened and sintered as a binder, polishing is performed while supplying a mixed aqueous solution of glycine, hydrogen peroxide, and benzotriazole onto the polishing pad. As a result, the same effect as that obtained when a polyvinyl chloride polishing pad was used was obtained.
[0089]
(Comparative Example 2)
In place of the polyvinyl chloride polishing pad used in Example 7, a polishing pad containing impurities having a particle size of 0.7 μm or more was used, and planarization CMP was performed on the silicon oxide film in the same manner as in Example 7. . As a result, many scratches having a depth or width greater than the average particle diameter of the abrasive particles were confirmed on the silicon oxide film.
[0090]
(Example 8)
A polishing pad made of polyvinyl chloride that has been subjected to metal removal treatment with a hydrochloric acid / hydrogen peroxide mixed aqueous solution treatment is used as a polishing pad, and planarization CMP is performed on a silicon oxide film formed by a plasma CVD method using TEOS gas as a raw material. It was. As the abrasive, an aqueous solution containing 1% by weight of cerium oxide particles having an average particle diameter of 0.7 μm was used. As a result, no scratch having a depth of 0.1 μm or more was observed on the silicon oxide film.
[0091]
In this embodiment, a polishing pad made of polyvinyl chloride is used as the polishing pad 72 and polishing is performed while supplying an abrasive. As the polishing pad, cerium oxide particles having an average particle diameter of 600 nm are used as phenol. When a resin (thermosetting resin) is hardened and sintered as a binder, polishing is performed while supplying a mixed aqueous solution of glycine, hydrogen peroxide, and benzotriazole onto the polishing pad. As a result, the same effect as that obtained when a polyvinyl chloride polishing pad was used was obtained.
[0092]
(Comparative Example 3)
Flattening CMP was performed on the silicon oxide film in the same manner as in Example 8 except that a polishing pad not subjected to metal removal treatment was used instead of the polyvinyl chloride polishing pad used in Example 8. As a result, many scratches having a depth or width greater than the average particle diameter of the abrasive particles were confirmed on the silicon oxide film.
[0093]
Example 9
FIG. 21 is a schematic view showing a polishing surface plate portion of a polishing apparatus according to the fourth aspect of the present invention. In the figure, reference numeral 91 denotes a rotatable SUS polishing platen. A disc-shaped polishing pad 92 made of hard plastic (polyvinyl chloride: thermal conductivity 0.08 to 0.34) and having a diameter of about 60 cm is attached on the polishing surface plate 71. A plurality of grooves 93 having a depth of 1 mm and a width of 2 mm are formed in a lattice shape on the polishing surface of the polishing pad 92. In addition, a coolant circulation path 94 is inserted at the interface between the polishing surface plate 91 and the polishing pad 92, and the coolant (fluid) such as cooling water is circulated to adjust the temperature (maintenance) of the polishing pad. It is possible. Further, the polishing surface plate 91 and the polishing pad 92 are provided with a discharge port 93a communicating with each other, and the discharge port 93a of the polishing pad 92 opens to the outside. The discharge port 93 a is configured to circulate a part of the refrigerant flowing through the refrigerant circulation path 94 and discharge a part of the refrigerant onto the polishing pad 92.
[0094]
The object to be polished is pressed onto the polishing pad 92 by lowering the top ring holding the object to be polished against the polishing surface plate 91.
[0095]
Using the polishing apparatus, CMP was performed on the Cu embedded wiring. As the abrasive, a mixture of glycine, hydrogen peroxide, benzotriazole aqueous solution, and colloidal silica was used. The abrasive was used as a refrigerant by cooling, and kept at 14 ° C. ± 1 ° C. by passing it through the refrigerant circuit 94. Further, a part of the abrasive was discharged onto the polishing pad 92 from the discharge port 93a. As a result, the polishing rate was about 500 nm / min, which was sufficient for CMP, and no scratches with a depth of 20 nm or more were found on the polished surface of the Cu wiring.
[0096]
In the present embodiment, a polishing pad made of polyvinyl chloride is used as the polishing pad 92, and the polishing process is performed while supplying the abrasive. If the Young's modulus is at least 1 GPa, the polishing is performed. It has been found that the same effect as described above can be obtained by using a so-called grindstone instead of the pad 92. Specifically, as a polishing pad, silica particles having an average particle size of 30 nm are sintered with phenol resin (thermosetting resin) as a binder, and glycine, hydrogen peroxide solution, and benzotriazole are used. Polishing was performed while supplying the mixed aqueous solution onto the polishing pad. As a result, the same effect as in the case of using the polyvinyl chloride polishing pad was obtained in terms of polishing rate and suppression of scratches.
[0097]
(Example 10)
As a polishing pad, a polishing pad comprising a plurality of independent parts formed by laminating a layer made of polyvinyl chloride as a polishing surface and a layer made of an elastic material made of rubber, woven fabric, nonwoven fabric or the like on the polishing surface plate side. The CMP was performed on the Cu embedded wiring. As an abrasive, a mixture of glycine, hydrogen peroxide, a benzotriazole aqueous solution, and colloidal silica having an average particle size of 70 μm was used. As a result, the polishing rate was about 50 nm / min, which was a sufficient rate for CMP. Further, local abnormal polishing of the surface to be polished due to the protruding portion of the polishing surface was not confirmed.
[0098]
In the above embodiment, a Cu film is used as an object to be polished, but a Cu film containing a small amount of impurities, a film made of a metal other than Cu, such as Ag, Al, W, or the like, and these as a main component. Plasma CVD film, BPSG film, fluorine-added SiO film formed using TEOS gas as a raw material₂A silicon oxide film such as a film or a thermal oxide film may be used.
[0099]
In the present embodiment, a polishing pad made of polyvinyl chloride is used as the polishing pad 92, and the polishing process is performed while supplying the abrasive. If the Young's modulus is at least 1 GPa, the polishing is performed. It has been found that the same effect as described above can be obtained by using a so-called grindstone instead of the pad 92. Specifically, as a polishing pad, silica particles having an average particle size of 30 nm are sintered with phenol resin (thermosetting resin) as a binder, and glycine, hydrogen peroxide solution, and benzotriazole are used. When the polishing was performed while supplying the mixed aqueous solution onto the polishing pad, the same effect as in the case of using the polishing pad made of polyvinyl chloride was obtained in suppressing dishing.
[0100]
(Example 11)
Example 11 is an example according to the fifth aspect of the present invention.
[0101]
22A is a schematic view showing a polishing apparatus according to the fifth aspect of the present invention, and FIG. 22B is a plan view of the polishing apparatus shown in FIG. In the figure, reference numeral 101 denotes a SUS top ring. The top ring 101 is connected to a drive mechanism (not shown) for raising and lowering the top ring and a cylinder mechanism that applies a load to the top ring 101 by a fluid. This cylinder mechanism presses the object to be polished 102 against the polishing pad 103.
[0102]
The polishing pad 103 is made of polyvinyl chloride and is stuck on a polishing surface plate 104 made of SUS. A concentric first groove 105 having a depth of 3 mm and a width of 15.2 cm for accommodating the object to be polished 102 is formed on the surface of the polishing pad 103, and further, the bottom surface of the first groove, that is, the object to be polished is formed. A grid-like second groove 25 having a depth of 1 mm and a width of 2 mm is formed on the contact surface with the body.
[0103]
Next, a method of forming a Cu buried wiring using the polishing apparatus having the top ring will be described.
[0104]
As a sample, a groove (width: 0.4 to 100 μm, depth: 0.4 μm) is formed in a silicon oxide film formed on a silicon substrate, and a Cu film having a thickness of 600 nm is formed thereon by sputtering. Was used.
[0105]
First, the workpiece 102 was held on the top ring 101 by a vacuum chuck mechanism (not shown) provided in the top ring 101, and then the top ring 101 and the polishing surface plate 104 were rotated with respect to each other. Next, the top ring 101 is lowered to bring the sample into contact with the polishing pad 103, and 280 gf / cm by the cylinder mechanism.²The surface load (arrow in the figure) was applied to the top ring 101 to press the sample against the polishing pad.
[0106]
Polishing was performed by supplying an abrasive in this state. At this time, the surface to be polished of the object to be polished was in the state of being present in the abrasive. After the polishing was completed, the rotation of the top ring 101 and the polishing surface plate 104 was stopped, and the object 102 was removed from the polishing pad 103, and then the object 102 was cleaned.
[0107]
The abrasive used was a mixture of glycine, hydrogen peroxide, benzotriazole aqueous solution and colloidal silica, and the temperature was controlled at 14 ° C. ± 1 ° C.
[0108]
In the sample polished as described above, the dishing amount of Cu in a wide concave portion having a width of 100 μm could be suppressed to 50 nm. The polishing rate was 3000 angstroms / minute, which was a sufficient rate for CMP. On the other hand, for comparison, when the sample was polished using the polishing pad 102 without the first groove 105, the amount of Cu dishing was suppressed, but the polishing rate was not satisfactory.
[0109]
Further, in the polishing apparatus of the fifth invention, a groove having a depth of 3 mm is formed as the first groove 105 into which the object to be polished is dropped. The depth of the groove is such that the polishing surface of the object to be polished is in the abrasive. There is no problem even if it is deep and shallow. Further, as shown in FIGS. 23A and 23B, even when the first groove 105 is formed so as to accommodate the top ring 101 that supports the object to be polished 102, the same effect as described above is obtained. .
[0110]
Further, in the fifth invention, as shown in FIG. 24, a polishing agent receiver 109 made of polyvinyl chloride is provided around a polishing surface plate 104 having a top ring 101 and a polishing pad 103, and the object to be polished 102 and the polishing target are polished. The pad 103 may be immersed in the abrasive 107 or, as shown in FIG. 25, an abrasive receiver 109 is provided at the outer peripheral end of the polishing pad 103 so that the object 102 and the polishing pad 103 are made of the abrasive 107. It is good also as a structure immersed in. However, in these structures, the circulation efficiency of the abrasive 107 is slower than the structures shown in FIGS. 22 and 23, and this is caused by the temperature change of the abrasive 107 and the formation of secondary particles due to the aggregation of the abrasive 107. Changes in the polishing rate may occur. In order to prevent this, it is preferable to circulate the abrasive 107 by providing a temperature adjusting device 110 for adjusting the temperature of the abrasive 107 and a filter 111 for removing secondary particles.
[0111]
In this embodiment, Cu is used as an object to be polished, but Cu containing a small amount of impurities, metals other than Cu, such as Ag, Al, W, alloys thereof, silicon oxide, B, Even when silicon oxide containing impurities such as P and F was used as an object to be polished, the same excellent effect was obtained. Moreover, the same effects as described above were obtained even when abrasive particles other than colloidal silica, such as alumina or cerium oxide, were used as the abrasive particles. Moreover, the same effect was acquired even if it used the grindstone holding the silica particle, the alumina particle, and the cerium oxide particle instead of the polishing pad.
[0112]
In this embodiment, a polishing pad made of polyvinyl chloride is used as the polishing pad 103, and the polishing process is performed while supplying an abrasive. If the Young's modulus is at least 1 GPa, the polishing is performed. It has been found that the same effect as described above can be obtained even if a so-called grindstone is used instead of the pad 103. Specifically, as a polishing pad, silica particles having an average particle size of 30 nm are sintered with phenol resin (thermosetting resin) as a binder, glycine, hydrogen peroxide solution, and benzotriazole When the polishing was performed while supplying the mixed aqueous solution onto the polishing pad, the same effect as that obtained when the polishing pad made of polyvinyl chloride was used was obtained in suppressing the polishing rate and dishing.
[0113]
【The invention's effect】
As described above, the polishing apparatus of the present invention can greatly suppress dishing due to frictional heat generated during polishing, improve the in-plane uniformity of the polishing rate, and improve the stability of the polishing rate. In addition, scratches on the object to be polished during polishing can be extremely reduced. Therefore, the polishing process can be stably performed with high reliability in the planarization of the interlayer insulating film, the formation of the metal plug, and the formation of the embedded metal wiring in the LSI multilayer wiring forming process.
[0114]
In addition, the polishing apparatus of the present invention can greatly suppress dishing due to frictional heat generated during polishing, improve the in-plane uniformity of the polishing rate, and improve the stability of the polishing rate. Furthermore, it is possible to detect the polishing pad repositioning time or the dressing time, and the material can be used efficiently. In addition, it is possible to predict an accurate polishing end point, so that the processing accuracy in the semiconductor manufacturing process can be improved, and the yield can be remarkably improved.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of a polishing apparatus.
2A is a cross-sectional view showing an example of a top ring of the polishing apparatus according to the first aspect of the present invention, and FIG. 2B is a plan view of the top ring shown in FIG.
FIG. 3 is a cross-sectional view showing another example of the top ring of the polishing apparatus according to the first aspect of the present invention.
FIGS. 4A and 4B are schematic views for explaining refrigerant circulation in the top ring.
FIGS. 5A and 5B are cross-sectional views illustrating a process of performing CMP using the polishing apparatus according to the first aspect of the present invention, and FIG. 5C is a cross-sectional view of performing CMP using a conventional polishing apparatus. Sectional drawing explaining the case.
FIG. 6 is a graph showing the relationship between dishing amount and wiring width.
FIG. 7 is a cross-sectional view showing another example of the top ring of the polishing apparatus according to the first aspect of the present invention.
FIG. 8 is a schematic view showing a polishing apparatus according to a second invention of the present invention.
9 is a schematic view showing a part of the polishing apparatus shown in FIG.
FIG. 10 is a graph showing the relationship between the monitored current value (torque), dynamic friction force, and polishing rate with respect to the number of polishing times.
FIG. 11 is a graph showing the relationship between the current value (torque) and the polishing rate of the Cu film.
FIG. 12 is a graph showing the relationship between the monitored current value and the final Cu film processing thickness with respect to the number of polishing times.
FIG. 13 is a schematic view showing a polishing surface plate portion of a polishing apparatus according to a third invention of the present invention.
FIG. 14 is a schematic view showing a polishing surface plate portion of a polishing apparatus according to a third invention of the present invention.
FIG. 15 is a schematic view showing a polishing platen portion of a polishing apparatus according to a third invention of the present invention.
FIG. 16 is a schematic view showing a polishing platen part of a polishing apparatus according to a third invention of the present invention.
FIG. 17 is a schematic view showing a polishing surface plate portion of a conventional polishing apparatus.
FIG. 18 is a schematic view showing a polishing platen part of a polishing apparatus according to a third invention of the present invention.
FIG. 19 is a graph showing the relationship between wiring width and dishing amount.
FIG. 20 is a schematic view showing a state of a surface of a polishing pad of a polishing apparatus according to a fourth invention of the present invention.
FIG. 21 is a schematic view showing a polishing surface plate portion of a polishing apparatus according to a fourth invention of the present invention.
22A is a schematic view showing a polishing apparatus according to a fifth aspect of the present invention, and FIG. 22B is a plan view of the polishing apparatus shown in FIG.
23A is a schematic view showing a polishing apparatus according to a fifth aspect of the present invention, and FIG. 23B is a plan view of the polishing apparatus shown in FIG.
FIG. 24 is a schematic view showing a polishing apparatus according to the fifth aspect of the present invention.
FIG. 25 is a schematic view showing a polishing apparatus according to the fifth aspect of the present invention.
[Explanation of symbols]
1, 11, 21, 45, 54, 101 ... top ring, 2, 17, 41, 53, 102 ... polished body, 3 ... elastic member, 4, 44, 51, 71, 91, 104 ... polishing surface plate, 5, 52, 72, 81, 92, 103 ... polishing pad, 6, 107 ... abrasive, 7, 60 ... abrasive supply tube, 8 ... discharge part, 11a ... rotating shaft part, 11b ... holding part, 12 ... gap , 13 ... refrigerant supply pipe, 14 ... refrigerant discharge pipe, 15 ... storage part, 16 ... communication hole, 16a ... long hole, 16b ... round hole, 18 ... seal ring, 22 ... vacuum source, 23 ... temperature controller, 24 ... Refrigerant pressure source, 25 ... Pressure regulator, 31 ... Silicon substrate, 32 ... Silicon oxide film, 33 ... Wiring groove, 34 ... Cu film, 42 ... Vacuum chuck, 43 ... Temperature control mechanism, 55 ... Cu lump 56 ... Torque monitor, 57 ... Current monitor, 58, 59 ... Driving means 61 ... friction force monitor, 73, 93 ... groove, 74, 94 ... refrigerant circulation path, 75 ... member, 76 ... abrasive supply pipe, 77 ... abrasive discharge pipe, 78 ... abrasive, 82 ... polishing surface, 84 ... Groove part, 93a ... outlet, 105 ... first groove, 106 ... second groove, 109 ... abrasive receiver, 110 ... temperature adjusting device, 111 ... filter.

Claims (2)

A polishing surface plate to which a polishing pad is attached; a polishing object holding means for holding the object to be polished so that a surface to be polished of the object to be polished faces the polishing pad; and the polishing surface plate, A fluid flow means for allowing a fluid to control the temperature of the polishing pad, and the polishing pad interposed between the polishing platen and the polishing pad, and a part of the upper surface thereof is exposed from the polishing pad. A polishing apparatus having a high thermal conductivity member having a higher thermal conductivity, and while relatively supplying the abrasive onto the polishing pad, moving the polishing platen and the object holding means relatively A polishing method for polishing the object to be polished,
During the polishing process, the high thermal conductivity member comes into contact with the abrasive and controls the temperature of the surface to be polished of the object to be polished. A polishing surface plate to which a polishing pad is attached; a polishing object holding means for holding the object to be polished so that a surface to be polished of the object to be polished faces the polishing pad; and the polishing surface plate, A fluid flow means for allowing a fluid to control the temperature of the polishing pad, and the polishing pad interposed between the polishing platen and the polishing pad, and a part of the upper surface thereof is exposed from the polishing pad. A polishing apparatus comprising a high thermal conductivity member containing a liquid having a higher thermal conductivity than the polishing surface plate and the object holding means relative to each other while supplying an abrasive onto the polishing pad. A polishing method for performing a polishing process on the object to be polished,
During the polishing process, the high thermal conductivity member comes into contact with the abrasive and controls the temperature of the surface to be polished of the object to be polished.

Images