JP2005277396A - Substrate processing method and apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a substrate processing method and apparatus capable of polishing the metal film of a substrate in such a state that a native oxide on the metal film formed on the substrate is removed , and of realizing the uniform planarization of the substrate. <P>SOLUTION: The substrate processing apparatus includes a processing unit for removing a native oxide of a metal that is formed on the surface of the metal film on a wafer W and polishing units 16 and 17 for performing chemical mechanical polishing of the metal film of the wafer W. The processing unit is a wet etching unit 14 using a chemical liquid capable of dissolving the native oxide of the metal or a dry etching unit 206 using a gas capable of reducing or etching the native oxide of the metal. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a substrate processing method and apparatus, and more particularly to a substrate processing method and apparatus for polishing a substrate such as a semiconductor wafer to a flat and mirror surface.

  In recent years, as semiconductor devices are highly integrated, circuit wiring is becoming finer and the distance between wirings is becoming narrower. In particular, in the case of photolithography having a line width of 0.5 μm or less, the depth of focus becomes shallow, so that the flatness of the imaging surface of the stepper is required. As one means for flattening the surface of such a semiconductor wafer, a polishing apparatus that performs chemical mechanical polishing (CMP) is known.

  This type of chemical mechanical polishing (CMP) apparatus includes a polishing table having a polishing pad on its upper surface and a top ring. Then, the substrate (wafer) is interposed between the polishing table and the top ring, and the substrate is pressed against the polishing table by the top ring while supplying the polishing liquid (slurry) to the surface of the polishing pad. Is polished flat and mirror-like.

  When the metal film formed on the surface of the substrate is planarized by chemical mechanical polishing, for example, the metal film is oxidized by the oxidizing agent in the slurry, and at the same time, the oxide film is immediately insoluble by the chelating agent in the slurry. Complexation is performed, and this complex is removed by polishing with abrasive grains contained in the slurry.

  However, when a metal film such as copper is formed on the surface of the substrate, a natural oxide film may grow on the metal film due to moisture or oxygen in the air before polishing. When such a natural oxide film is formed on the metal film, the surface of the substrate is hardly complexed by the chelating agent. Further, the natural oxide film itself has a property that it is harder to polish than the complex. Therefore, when the formed natural oxide film has a non-uniform thickness, polishing does not proceed locally, and uniform planarization may not be realized.

  The present invention has been made in view of such problems of the prior art, and the metal film on the substrate is polished in a state in which the natural oxide film on the metal film formed on the substrate is removed, and the substrate is uniformly flattened. It is an object of the present invention to provide a substrate processing method and apparatus capable of realizing the above.

  To achieve the above object, according to the first aspect of the present invention, there is provided a method for treating a substrate having a metal film formed on the surface thereof. According to this substrate processing method, the metal oxide film formed on the surface of the metal film on the substrate is removed, and then the metal film on the substrate is planarized.

  According to the present invention, since the metal film on the substrate can be flattened in a state where the natural oxide film on the metal film formed on the substrate is removed, uniform flattening of the substrate can be realized with good reproducibility. can do.

  According to a preferred aspect of the present invention, as the removal treatment, a wet treatment using a chemical solution capable of dissolving the natural oxide film of the metal is performed. Examples of such a chemical solution include an acidic chemical solution or a chelating agent solution that forms a soluble complex. If the metal coating formed on the substrate is copper, inorganic acids such as hydrofluoric acid, sulfuric acid, hydrochloric acid and phosphoric acid, organic acids such as formic acid, acetic acid, propionic acid, succinic acid, malonic acid, succinic acid and malic acid Alternatively, a solution of a chelating agent that forms a soluble complex such as an alkali solution of a halide, carboxylic acid or a salt thereof, ammonia, ethylenediaminetetraacetic acid (EDTA), glycine, or the like can be used.

  According to a preferred aspect of the present invention, as the removal treatment, a dry treatment using a gas capable of reducing or etching the natural oxide film of the metal is performed. For example, using a mixed gas of hydrogen and argon as a process gas, the surface of the substrate is irradiated with hydrogen plasma generated by electron cyclotron resonance (ECR) to etch the natural oxide film. Depending on the properties of the gas used, the surface of the substrate may be etched by reactive ion etching (RIE), or the surface of the substrate may be etched by magnetic excitation reactive ion etching (MERIE). In addition to hydrogen, ammonia can be considered as a gas that can be used. Further, the natural oxide film on the surface of the substrate may be reduced and removed by heating hydrogen, ammonia, an organic acid such as formic acid or acetic acid to about several hundred degrees Celsius to form a reducing atmosphere. Further, the planarization treatment can be performed by any one of chemical mechanical polishing, electrolytic processing, and composite electrolytic processing in which electrolytic processing and mechanical polishing are combined.

  According to the 2nd aspect of this invention, the grinding | polishing method which presses the board | substrate with which the metal film was formed in the surface on a grinding | polishing surface and grind | polishes this metal film is provided. According to this polishing method, the first polishing step is performed to remove at least the natural oxide film of the metal formed on the metal film on the substrate by polishing, and then the metal film on the substrate is removed by polishing. 2 polishing process is performed.

  According to the present invention, the metal coating on the surface of the substrate is polished in a state where the natural oxide film on the metal coating formed on the substrate is removed without greatly changing the configuration of the polishing apparatus used conventionally. And uniform flattening can be realized.

  According to a preferred aspect of the present invention, as the first polishing step, the substrate is pressed against the polishing surface with a first pressure to polish the substrate, and as the second polishing step, the substrate is The substrate is polished by pressing against the polishing surface at a second pressure different from the first pressure. In this case, it is preferable that the first pressure is larger than the second pressure. According to such a polishing method, it is not necessary to change the polishing liquid during the polishing, and the polishing process can be performed continuously.

  According to a preferred aspect of the present invention, as the first polishing step, the substrate is pressed against the polishing surface while supplying the first polishing liquid to the polishing surface, and the substrate is polished. As the second polishing step, the substrate is pressed by pressing the substrate against the polishing surface while supplying a second polishing solution different from the first polishing solution to the polishing surface.

  According to a preferred aspect of the present invention, a water supply step of pressing the substrate against the polishing surface while supplying water to the polishing surface between the first polishing step and the second polishing step. Do. When changing the polishing pressure (pressure for pressing the substrate against the polishing surface) between the first polishing step and the second polishing step, the temperature may increase due to the polishing pressure in the first polishing step. By performing the water supply step between the first polishing step and the second polishing step, the temperature of the processing point can be once lowered, and the subsequent second polishing step can be performed with high accuracy. Even when the polishing liquid is changed between the first polishing process and the second polishing process, the remaining amount of the polishing liquid used in the first polishing process is reduced, and the polishing liquid used in the second polishing process is used. The adverse effect on the polishing characteristics can be minimized.

  According to a preferred aspect of the present invention, the end of the first polishing step is detected based on the frictional force between the substrate and the polishing surface. As a result, the first polishing process can be completed at an appropriate timing, and the second polishing process can be performed at an appropriate timing, so that satisfactory flattening can be realized.

  According to the 3rd aspect of this invention, the grinding | polishing method which presses the board | substrate with which the metal film was formed in the surface on a grinding | polishing surface and grind | polishes this metal film is provided. According to this polishing method, a first polishing step is performed in which the substrate is pressed against the polishing surface with a first pressure to polish the substrate, and then the substrate is removed while supplying water to the polishing surface. A water supply step for pressing the polishing surface is performed. After the water supplying step, the substrate is pressed against the polishing surface with a second pressure larger than the first pressure to polish the substrate.

  Increasing the polishing pressure tends to cause a temperature rise at the processing point, but if it exceeds a certain limit, the temperature will not decrease easily even if the polishing pressure is lowered in the subsequent polishing process, and the polishing liquid (slurry) The polishing characteristics of the slurry may be deteriorated due to deterioration of the oxidizing agent in the inside, and the polishing rate may be lowered in the subsequent polishing process or the polishing characteristics may be adversely affected. According to the polishing method described above, the supply of the polishing liquid is stopped and the polishing is performed by supplying water between the first polishing step and the second polishing step, so that the temperature of the processing point can be temporarily lowered. This makes it possible to perform the second polishing step with high accuracy.

  According to the fourth aspect of the present invention, there is provided a substrate processing apparatus for polishing a metal film on a substrate. The substrate processing apparatus includes a processing unit that removes a natural oxide film of the metal formed on the surface of the metal coating, and a planarization unit that planarizes the metal coating on the substrate. This processing unit performs a wet process using a chemical solution capable of dissolving the metal natural oxide film, or performs a dry process using a gas capable of reducing or etching the metal natural oxide film. It can be a dry processing unit. The flattening unit includes a chemical mechanical polishing unit that chemically and mechanically polishes the metal coating on the substrate, an electrolytic processing unit that performs electrolytic processing on the metal coating on the substrate, and a composite electrolysis that combines electrolytic processing and mechanical polishing. It can be any of the complex electrolytic processing units that perform the processing on the metal film of the substrate.

  According to the present invention, since the metal film on the substrate can be flattened in a state where the natural oxide film on the metal film formed on the substrate is removed, uniform flattening of the substrate can be realized with good reproducibility. be able to.

  Hereinafter, embodiments of a substrate processing apparatus according to the present invention will be described in detail with reference to FIGS. 1 to 19, the same or corresponding components are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a plan view showing a polishing apparatus as a substrate processing apparatus in the first embodiment of the present invention. As shown in FIG. 1, the polishing apparatus includes four load / unload stages 2 on which a wafer cassette 1 for stocking a large number of semiconductor wafers is placed. A travel mechanism 3 is provided along the load / unload stage 2, and a first transfer robot 4 having two hands is disposed on the travel mechanism 3. Further, a film thickness measuring device 100 is disposed adjacent to the traveling mechanism 3. The hand of the first transfer robot 4 can access each wafer cassette 1 and the film thickness measuring device 100 on the load / unload stage 2.

  Two cleaning / drying machines 5 and 6 are arranged on the side opposite to the wafer cassette 1 with the traveling mechanism 3 of the first transfer robot 4 as the axis of symmetry. The hand of the first transfer robot 4 can also access these washing / drying machines 5 and 6. Each of the cleaning machines 5 and 6 has a spin dry function of rotating the wafer at high speed to dry it. Between the two cleaning / drying machines 5 and 6, a wafer station 11 having four semiconductor wafer mounting tables 7, 8, 9 and 10 is disposed. Is accessible to the wafer station 11.

  A second transport robot 12 having two hands is disposed at a position where it can reach the cleaning machine 5 and the three mounting tables 7, 9, 10, and the cleaning / drying machine 6 and the three mounting tables 8, 9 are arranged. , 10 is provided with a third transfer robot 13 having two hands. Here, the mounting table 7 is used for delivering a semiconductor wafer between the first transfer robot 4 and the second transfer robot 12, and the mounting table 8 is provided between the first transfer robot 4 and the third transfer robot 13. Used to deliver semiconductor wafers. The mounting table 9 is used to transfer a semiconductor wafer from the second transfer robot 12 to the third transfer robot 13, and the mounting table 10 is used to transfer the semiconductor wafer from the third transfer robot 13 to the second transfer robot 12. Used for. The mounting table 9 is located on the mounting table 10.

  As a wet processing unit that is adjacent to the cleaning machine 5 and accessible by the hand of the second transfer robot 12, a natural oxide film of a metal film formed on the surface of a substrate such as a semiconductor wafer is dissolved and removed by etching. The wet etching unit 14 is disposed. A cleaning machine 15 for cleaning the polished wafer is disposed adjacent to the cleaning machine 6 at a position accessible by the hand of the third transfer robot 13.

  As shown in FIG. 1, the polishing apparatus includes two polishing units 16 and 17 as flattening units for flattening the metal film on the substrate. Each of the polishing units 16 and 17 includes two polishing tables and one top ring for holding the wafer and polishing the wafer while pressing the wafer against the polishing table. That is, the polishing unit 16 includes a first polishing table 18, a second polishing table 19, a top ring 20, a polishing liquid supply nozzle 21 for supplying a polishing liquid to the polishing table 18, and a polishing table 18. A dresser 22 for performing dressing and a dresser 23 for performing dressing of the polishing table 19 are provided. The polishing unit 17 includes a first polishing table 24, a second polishing table 25, a top ring 26, a polishing liquid supply nozzle 27 for supplying a polishing liquid to the polishing table 24, and a polishing table 24. A dresser 28 for dressing and a dresser 29 for dressing the polishing table 25 are provided.

  The polishing unit 16 is provided with a reversing machine 30 for reversing the semiconductor wafer at a position accessible by the hand of the second transport robot 12, and the reversing machine 30 receives the semiconductor wafer by the second transport robot 12. Be transported. Similarly, the polishing unit 17 is provided with a reversing device 31 for reversing the semiconductor wafer at a position accessible by the hand of the third transport robot 13. The reversing device 31 is equipped with a semiconductor wafer by the third transport robot 13. Is transported.

  Below these reversing machines 30 and 31 and the top rings 20 and 26, a rotary transporter 32 that conveys the wafer between the reversing machines 30 and 31 and the top rings 20 and 26 is arranged. The rotary transporter 32 is provided with four stages on which wafers are placed at equal intervals so that a plurality of wafers can be loaded simultaneously. The wafer transferred to the reversing machines 30 and 31 is placed below the rotary transporter 32 when the center of the stage of the rotary transporter 32 and the center of the wafer chucked by the reversing machine 30 or 31 are in phase. The lifter 33 or 34 lifted and lowered is conveyed onto the rotary transporter 32.

  The wafer placed on the stage of the rotary transporter 32 is conveyed below the top ring 20 or 26 as the rotary transporter 32 rotates. The top ring 20 or 26 is previously swung to the position of the rotary transporter 32. When the center of the top ring 20 or 26 is in phase with the center of the wafer mounted on the rotary transporter 32, the pusher 35 or 36 disposed below them moves up and down, so that the wafer is removed from the rotary transporter 32. It is transferred to the top ring 20 or 26.

  The wafer transferred to the top ring 20 or 26 is adsorbed by the vacuum adsorption mechanism of the top ring 20 or 26, and the wafer is conveyed to the polishing table 18 or 24 while being adsorbed. Then, the wafer is polished by a polishing surface made of a polishing pad or a grindstone mounted on the polishing table 18 or 24. The above-described second polishing tables 19 and 25 are disposed at positions where the top rings 20 and 26 can reach, respectively. Thus, after the wafer is polished by the first polishing tables 18 and 24, the wafer can also be polished by the second polishing tables 19 and 25. The polished wafer is returned to the reversing machines 30 and 31 through the same route.

  FIG. 2 is a longitudinal sectional view showing the wet etching unit 14 in the polishing apparatus of FIG. As shown in FIG. 2, the wet etching unit 14 includes a rotation drive body 142 that is rotatably provided in a cylinder 140 via a bearing 141, and an upper portion of the rotation drive body 142. And a chuck portion 143 for gripping. A pulley 144 is attached to the lower end of the rotary driving body 142, and the pulley 144 is connected to the motor 147 through a belt 145 and a pulley 146. Therefore, the rotation driving body 142 is rotated by the rotation of the motor 147, and the wafer W held by the chuck portion 143 is rotated. As the chuck portion 143, a chuck mechanism such as a centrifugal chuck mechanism or a pin chuck mechanism that grips the wafer with a centrifugal force by rotation can be used.

  A chemical / pure water nozzle 148 for injecting a chemical or pure water for etching a metal natural oxide film formed on the surface of the wafer W onto the wafer W is provided above the rotary drive 142. Examples of the chemical solution include an acidic chemical solution or a chelating agent solution that forms a soluble complex. If the metal coating formed on the substrate is copper, inorganic acids such as hydrofluoric acid, sulfuric acid, hydrochloric acid and phosphoric acid, organic acids such as formic acid, acetic acid, propionic acid, succinic acid, malonic acid, succinic acid and malic acid Alternatively, a solution of a chelating agent that forms a soluble complex such as an alkali solution of an amino acid such as halide, carboxylic acid or a salt thereof, ammonia, ethylenediaminetetraacetic acid (EDTA), or glycine is used. In addition, these chemical solutions can be mixed and used as a mixed solution. Further, when it is difficult to spread the chemical liquid uniformly on the entire wafer W due to the problem of wettability of the surface, a surfactant may be added to the chemical liquid to improve the wettability and increase the processing efficiency.

  At the time of etching, the chemical solution is supplied from the chemical solution / pure water nozzle 148 toward the vicinity of the center of the wafer W. Since the chemical solution supplied to the vicinity of the center of the wafer W moves toward the peripheral edge of the wafer W due to the centrifugal force generated by the rotation of the wafer W, the chemical solution can be spread over the entire surface of the wafer W. Note that the chemical solution is not supplied to the portion where the wafer W is gripped by the chuck portion 143. For example, when a centrifugal chuck mechanism is used, the rotational speed of the rotary drive 142 is temporarily increased or The centrifugal force is increased or decreased to slide the wafer W relative to the chuck portion 143, thereby changing the gripping position of the wafer W and supplying the chemical solution over the entire area of the wafer.

  When the etching of the metal natural oxide film is completed, the supply source of the chemical / pure water nozzle 148 is switched by a switching controller (not shown), and pure water is supplied from the chemical / pure water nozzle 148 to the wafer W. By supplying the pure water, the chemical solution remaining on the wafer W is rinsed and cleaned. The method of supplying the chemical solution to the wafer W is not limited to the example using the nozzle as shown in FIG. 2, and the wafer W may be immersed in the chemical solution. Alternatively, a chemical solution coating apparatus widely used in substrate processing such as a roll type, a spray type, or a spin type can be used.

  Here, as shown in FIG. 2, a film thickness measuring device 149 having a light projecting unit 149a, a light receiving unit 149b, and a calculation unit 149c is disposed above the rotary driving body 142 in the wet etching unit 14. . The film thickness measuring instrument 149 is swingable by being connected to a swing mechanism (not shown), and can irradiate the entire surface of the wafer W from the light projecting unit 149a. With such a film thickness measuring device 149, the light reflected from the wafer W can be analyzed, the film thickness of the wafer W can be measured during the etching process, and the end point of etching can be detected (In-Situ).

  The light emitted from the light projecting unit 149a of the film thickness measuring device 149 may be either short wavelength light or multi-wavelength light. In this embodiment, an optical type film thickness measuring device 149 has been described. However, an eddy current is generated in a metal film including a natural oxide film by supplying an AC signal to the sensor coil, and this eddy current is detected. A film thickness measuring device using an eddy current sensor detected by a sensor coil of a circuit can also be used. In this case, the sensor coil may be on the upper surface (ie, the wiring forming surface) side of the wafer W or on the rear surface side of the wafer.

  With the film thickness measuring device 149 described above, measurement data of the film thickness distribution on the entire surface of the wafer W, particularly the film thickness distribution in the radial direction of the wafer W can be obtained. In this case, the measurement data can be fed back to the polishing units 16 and 17 to optimize the polishing rate in each radial direction in the polishing process. For example, by setting the pressing force of the wafer W by the top rings 20 and 26 to be higher in a relatively thick region and setting the polishing rate for each radial direction, higher in-plane uniformity is achieved. Polishing can be performed.

  FIG. 3 is a cross-sectional view showing the top ring 160 that can change the pressing force on the wafer W for each region. As shown in FIG. 3, the top ring 160 includes a top ring main body 161, a retainer ring 162 provided at a lower portion of the outer edge of the top ring main body 161, and a chucking plate 163 that moves up and down with respect to the top ring main body 161. I have. The top ring body 161 and the drive shaft 164 are connected to each other by a universal joint 165. The universal joint 165 includes a ball bearing mechanism including a ball 166 that tiltably supports the top ring body 161 on the lower end of the drive shaft 164, and a rotation transmission mechanism that transmits the rotation of the drive shaft 164 to the top ring body 161 (see FIG. Not shown).

  A wafer holding surface capable of profile control is formed on the lower surface of the chucking plate 163 by a plurality of elastic films 167 and 168. That is, the wafer is held by the seal ring 169 that abuts the outer periphery of the wafer W and seals the internal space together with the wafer W, the annular ring tube 170 provided in the internal space, and the circular center bag 171. The surface is divided into a plurality of divided pressure chambers 172 and 173. A pressure chamber 174 is formed inside the center bag 171, and a pressure chamber 175 is formed inside the ring tube 170.

  Fluid passages 176, 177, 178, and 179 communicate with the pressure chambers 172, 173, 174, and 175, respectively, and adjust the pressure of the pressure fluid supplied to the pressure chambers 172, 173, 174, and 175, respectively. Can be done. With such a configuration, the pressing force against the wafer W by each of the pressure chambers 172, 173, 174, and 175 can be controlled independently, and the polishing rates of the portions corresponding to the respective pressure chambers 172, 173, 174, and 175 can be controlled. Can be controlled.

  Next, the polishing process in the above-described polishing apparatus will be described. The wafer to be polished is accommodated in the wafer cassette 1 with the surface on which the metal film is formed facing upward, and the wafer cassette 1 accommodating a large number of wafers is placed on the load / unload stage 2. The first transfer robot 4 takes out one wafer from the wafer cassette 1 and transfers this wafer to the mounting table 7. Here, before the wafer is transferred to the mounting table 7, it can be transferred to the film thickness measuring device 100 and the film thickness of the natural oxide film on the wafer surface can be measured in advance. If the film thickness measuring device 100 measures the film thickness of the natural oxide film on the wafer surface and calculates the etching processing time corresponding to the film thickness of the natural oxide film by a control device (database) in the polishing apparatus. The natural oxide film etching time in the subsequent wet etching unit 14 can be set appropriately.

  The wafer placed on the mounting table 7 is transferred to the wet etching unit 14 by the second transfer robot 12. In the wet etching unit 14, as described above, the chemical solution for etching the natural oxide film is supplied from the chemical solution / pure water nozzle 148 (see FIG. 2) to the wafer, and the natural oxide film on the metal film on the wafer is supplied by the chemical solution. Dissolved and removed. When the etching of the metal natural oxide film is completed, the supply from the chemical solution / pure water nozzle 148 is switched from the chemical solution to the pure water, and the chemical solution remaining on the wafer W is rinsed and cleaned.

  The etched wafer is taken out from the wet etching unit 14 by the second transfer robot 12 and transferred to the reversing machine 30. In the reversing machine 30, the wafer is reversed and delivered to the rotary transporter 32 with the metal film forming surface facing downward. The rotary transporter 32 that has received the wafer rotates 90 degrees and conveys the wafer to the pusher 35. The wafer on the pusher 35 is attracted to the top ring 20 of the polishing unit 16 and moved onto the polishing table 18 where it is polished. As described above, after polishing on the first polishing table 18, polishing may be performed on the second polishing table 25.

  The polished wafer is delivered from the pusher 35 to the rotary transporter 32. The rotary transporter 32 that has received the wafer rotates 180 degrees and conveys the wafer to the reversing machine 31. In the reversing machine 31, the wafer is reversed, and the wafer is delivered to the third transfer robot 13 with the metal film forming surface facing upward. The third transfer robot 13 transfers the wafer to the cleaning machine 15, and the cleaning machine 15 cleans the wafer. The cleaned wafer is taken out from the cleaning machine 15 by the third transfer robot 13 and introduced into the cleaning / drying machine 6. In the cleaning / drying machine 6, the wafer is rinsed and dried, and the dried wafer is returned to the wafer cassette 1 by the first transfer robot 4.

  In this embodiment, two cleaning / drying machines 5 and 6, one wet etching unit 14, and one cleaning machine 15 are installed in the polishing apparatus, but this configuration is limited. is not. For example, one washing / drying machine, one etching unit, and two washing machines may be installed, or two washing / drying machines, one etching unit, and one washing / drying. You may install a machine. Alternatively, one cleaning machine, two etching units, and one cleaning / drying machine may be installed.

  In this embodiment, the example in which the wet etching unit 14 is provided as a processing unit different from the polishing units 16 and 17 has been described. However, the above-described wet etching mechanism may be incorporated in the polishing unit 16 or 17. Alternatively, an appropriate one of the chemicals used in the etching process is selected and supplied to the polishing table from the polishing liquid supply nozzles 21 and 27 of the polishing units 16 and 17 to perform the etching process on the polishing units 16 and 17. It can also be done within. In these cases, since the polishing treatment can be performed immediately after the etching treatment, the growth of the natural oxide film after the chemical treatment can be suppressed. Thus, in order to avoid the growth of the natural oxide film after the chemical treatment, it is preferable to perform the polishing treatment as soon as possible after the chemical treatment. If the chemical used for dissolving and removing the natural oxide film adversely affects the polishing performance of the slurry used in the polishing process, it is necessary to rinse the wafer with ultrapure water after the chemical process.

  FIG. 4 is a plan view showing a polishing apparatus as a substrate processing apparatus in the second embodiment of the present invention. As shown in FIG. 4, the polishing apparatus includes a load / unload stage 2 on which the wafer cassette 1 is placed, a first transfer robot 201 having a hand that can access the wafer cassette 1, and both sides of the first transfer robot 201. And the first transfer robot 201 and the vacuum chamber 204 arranged along the placement tables 202 and 203.

  Inside this vacuum chamber 204, there is a second transfer robot 205 having a hand accessible to the mounting table 202, and dry etching as a dry processing unit for reducing or etching a metal natural oxide film formed on the surface of the wafer. A unit 206 and a third transfer robot 207 having a hand that can access the mounting table 203 are accommodated. Shutters 208 and 209 are provided between the second transfer robot 205 and the dry etching unit 206 and between the third transfer robot 207 and the dry etching unit 206, respectively. The robot chamber A in which the second transfer robot 205 is installed and the robot chamber B in which the third transfer robot 207 is installed are connected to the vacuum pump 210 and each have a role as a load lock. The dry etching unit 206 is also connected to the vacuum pump 210.

  In addition, a shutter (not shown) used when transferring the wafer from the mounting table 202 to the second transport robot 205 is provided between the mounting table 202 and the second transport robot 205. Between the mounting table 203 and the third transfer robot 207, a shutter (not shown) used when transferring the wafer from the third transfer robot 207 to the mounting table 203 is provided.

  A fourth transfer robot 211 is disposed at a position that can reach the mounting table 203. Two washing / drying machines 212 and 213 are arranged on both sides of the fourth transfer robot 211. The washing / drying machines 212 and 213 have the same functions as the washing / drying machines 5 and 6 in the first embodiment. A mounting table 124 is disposed adjacent to the fourth transfer robot 211, and two cleaning machines 215 and 216 are disposed on both sides of the mounting table 124. The hand of the fourth transfer robot 211 can access the cleaning / drying machines 212 and 213, the mounting table 124, and the cleaning machines 215 and 216.

  A fifth transfer robot 217 having two hands is disposed at a position where the cleaning machine 215 and the mounting table 214 can be reached, and two hands are positioned at a position where the cleaning machine 216 and the mounting table 214 can be reached. A sixth transfer robot 218 having the same is disposed. A reversing device 219 is disposed at a position accessible by the hand of the fifth transfer robot 217, and a reversing device 220 is disposed at a position accessible by the hand of the sixth transport robot 218. Corresponding to these reversing machines 219 and 220, transporters 221 and 222 are provided.

  Adjacent to the transporters 221, 222, polishing units 223, 224 are arranged. The polishing unit 223 includes a polishing table 225, a top ring 226, and a pusher 227. The polishing unit 224 includes a polishing table 228, a top ring 229, and a pusher 230. Further, in the polishing apparatus according to the present embodiment, as shown in FIG. 4, a slurry supply device 231 and a chemical / pure water supply device 232 for supplying slurry to the polishing tables 225 and 228 of the polishing units 223 and 224, and control of the devices are provided. And a monitor 234 for monitoring the operation state of the apparatus.

  The dry etching unit 206 in the vacuum chamber 204 is for reducing or etching a natural oxide film on the surface of the wafer using a process gas. As shown in FIG. 4, the process gas supply device 235 is connected to the dry etching unit 206. It is connected. For example, the dry etching unit 206 uses a mixed gas of hydrogen and argon as a process gas and irradiates the surface of the wafer with hydrogen plasma generated by electron cyclotron resonance (ECR) to etch the natural oxide film. Depending on the properties of the gas used, the surface of the wafer may be etched by reactive ion etching (RIE), or the surface of the wafer may be etched by magnetic excitation reactive ion etching (MERIE). In addition to hydrogen, ammonia can be considered as a gas that can be used. In addition, a chamber for heat treatment is provided in the dry etching unit 206, and an atmosphere such as hydrogen, ammonia, organic acid such as formic acid or acetic acid is heated to about several hundred degrees Celsius, and the inside of the chamber is made a reducing atmosphere, so that the wafer surface The natural oxide film may be reduced and removed.

  Next, the polishing process in the above-described polishing apparatus will be described. The wafer to be polished is accommodated in the wafer cassette 1 with the surface on which the metal film is formed facing upward, and the wafer cassette 1 accommodating a large number of wafers is placed on the load / unload stage 2. The first transfer robot 201 takes out one wafer from the wafer cassette 1 and transfers this wafer to the mounting table 202. Then, the shutter between the mounting table 202 and the second transfer robot 205 is opened, and the wafer mounted on the mounting table 202 by the second transfer robot 205 is introduced into the robot chamber A in the vacuum chamber 204.

  After the wafer is loaded into the robot chamber A, the vacuum pump 210 is driven to evacuate the robot chamber A, the dry etching unit 206, and the robot chamber B. After the robot chamber A is evacuated, the shutter 208 between the robot chamber A and the dry etching unit 206 is opened, and the wafer is transferred into the dry etching unit 206 by the second transfer robot 205. In the dry etching unit 206, dry etching using the process gas described above is performed, and the natural oxide film on the surface of the wafer is reduced or etched.

  When dry etching is completed in the dry etching unit 206, the shutter 209 between the dry etching unit 206 and the third transfer robot 207 is opened, and the wafer is introduced into the robot chamber B by the third transfer robot 207. Thereafter, the vacuum in the robot chamber B is released, the shutter between the third transfer robot 207 and the mounting table 203 is opened, and the wafer is transferred from the third transfer robot 207 to the mounting table 203.

  The wafer placed on the mounting table 203 is transferred to the mounting table 214 by the fourth transfer robot 211. The wafer mounted on the mounting table 214 is transferred to the reversing device 219 by the fifth transfer robot 217. In the reversing machine 219, the wafer is reversed, and the wafer is delivered to the transporter 221 with the metal film forming surface facing downward. The wafer on the transporter 221 is attracted to the top ring 226 by the pusher 227 of the polishing unit 223, moved onto the polishing table 225, and is polished there.

  The polished wafer is transferred from the pusher 227 to the reversing device 219 via the transporter 221. In the reversing machine 219, the wafer is reversed and delivered to the fifth transfer robot 217 with the metal film forming surface facing upward. The fifth transport robot 217 transports the wafer to the cleaning machine 215, and the cleaning machine 215 cleans the wafer. The cleaned wafer is taken out from the cleaning machine 215 by the fourth transfer robot 211 and introduced into the cleaning / drying machine 212. In the cleaning / drying machine 212, the wafer is rinsed and dried. The dried wafer is transferred to the mounting table 203 by the fourth transfer robot 211, and the wafer mounted on the mounting table 203 is returned to the wafer cassette 1 by the first transfer robot 201.

  Note that after performing dry etching in the dry etching unit 206 and before polishing in the polishing unit 223, the wafer may be introduced into the cleaning machine 215 or 216 to perform cleaning. Further, depending on the selection of the cleaning process, the mounting table 203 and the fourth transfer robot 211 may be omitted. In this embodiment, the example in which the dry etching unit 206 is provided as a processing unit different from the polishing units 223 and 224 has been described. However, the above-described dry etching mechanism may be incorporated in the polishing unit 223 or 224.

  In the above-described embodiment, the example in which the natural oxide film is removed by a wet process using a chemical solution or a dry process using a gas has been described. However, the natural oxide film can also be removed by polishing in a polishing unit. That is, first, polishing is performed under conditions suitable for polishing the natural oxide film on the metal film on the wafer surface, the natural oxide film is polished and removed (first polishing step), and then the metal film on the wafer surface is polished. The condition is changed to a condition suitable for the removal, and the metal film on the wafer is removed (second polishing step). According to such a two-stage polishing method, the metal film on the wafer is removed in a state in which the natural oxide film on the metal film formed on the wafer is removed without greatly changing the configuration of the polishing apparatus used conventionally. Can be polished, and uniform flattening can be realized.

  Here, there may be a case where the metal film on the wafer surface can be polished to some extent under polishing conditions suitable for polishing the natural oxide film. In such a case, not only the natural oxide film but also the metal film may be polished to some extent in the first polishing step. However, if the first polishing process is continued excessively, for example, in the case of a copper embedded wiring formation process, a polishing residue may occur, or the amount of dishing increases, so that the planarization characteristics deteriorate. It is necessary to shift to the second polishing step before finishing the polishing of copper.

  As an example of such a two-stage polishing method, a method of changing the pressure (polishing pressure) for pressing the wafer against the polishing surface is conceivable. In general, since a natural oxide film is harder to polish than a metal film, for example, in the case of polishing copper, the first polishing step is, for example, 17.225 kPa (2.5 psi) or more, preferably 17.225 kPa. The natural oxide film is mainly removed by polishing at a high polishing pressure of ˜27.56 kPa (2.5 psi to 4.0 psi), and then the polishing pressure is set to, for example, 10.335 kPa (1.5 psi) as the second polishing step. ) Hereinafter, the metal film is polished and removed at a low pressure of preferably 10.335 kPa to 3.445 kPa (1.5 psi to 0.5 psi). In this way, by making the polishing pressure in the first polishing step higher than the polishing pressure in the second polishing step, the natural oxide film is mainly removed by polishing in the first polishing step, and the metal in the second polishing step. The coating can be removed by polishing.

  According to such a polishing method, the metal film on the wafer can be polished in a state where the natural oxide film on the metal film formed on the wafer surface is removed without providing a processing apparatus separately from the polishing unit. Uniform planarization can be realized. Further, it is not necessary to change the slurry during the polishing, and the polishing process can be performed continuously.

  Here, if the polishing pressure is increased in the first polishing step, the temperature at the processing point is likely to increase, but if it exceeds a certain limit, the process proceeds to the second polishing step and the polishing pressure is lowered. However, the temperature does not decrease easily, and the polishing characteristics of the slurry may be deteriorated due to deterioration of the oxidizing agent in the slurry, and the polishing speed in the second polishing step may be lowered and the polishing characteristics may be adversely affected. Therefore, it is preferable to stop the supply of the polishing liquid (slurry) between the first polishing process and the second polishing process, and perform a process of supplying water and polishing (water supply process). Thereby, the temperature of a process point can be once lowered | hung. After such a water supply process, a 2nd grinding | polishing process can be accurately performed by supplying polishing liquid (slurry) and transfering to a 2nd grinding | polishing process.

  FIG. 5 is a graph showing the effect of performing such a water supply process. The dotted line indicates the case where the water supply process is not performed, and the solid line indicates the case where the water supply process is performed. As shown in FIG. 5, by performing the water supply step between the first polishing step and the second polishing step, the temperature of the polishing surface (polishing pad) can be greatly reduced, and the amount of dishing can be suppressed. It was. In the example illustrated in FIG. 5, the dishing amount when the water supply step is not performed is 60 to 75 nm, and the dishing amount when the water supply step is performed is 40 to 60 nm.

  Further, as another example of the above-described two-stage polishing method, a method of changing the composition of the polishing liquid (slurry) supplied to the polishing surface can be considered. That is, in the first polishing step, a slurry having an acidic pH, a slurry from which the anticorrosive agent has been removed, a slurry containing a chelating agent that forms a soluble metal complex, and the like are used. The slurry used in the polishing process is used. Thus, the slurry used in the first polishing step is suitable for removing the natural oxide film, and the slurry for polishing the normal metal film in the second polishing step after the natural oxide film is removed by polishing. Change to According to such a method, without providing a processing apparatus separately from the polishing unit, the metal film on the wafer is polished and uniform flattened in a state where the natural oxide film on the metal film on the wafer is removed. Can be realized.

  In this case, the remaining polishing slurry used in the first polishing step may adversely affect the polishing characteristics of the slurry used in the second polishing step. Therefore, as in the case of changing the polishing pressure described above, the supply of the polishing liquid (slurry) is stopped between the first polishing process and the second polishing process, and the water supply process for supplying water is performed. Is preferred. By such a water supply process, the remaining amount of the slurry used in the first polishing process can be reduced, and adverse effects on the polishing characteristics of the slurry used in the second polishing process can be minimized.

  Here, in order to realize good planarization, it is necessary to end the first polishing process at an appropriate timing and shift to the second polishing process at an appropriate timing. Therefore, it is preferable to detect the end point of the first polishing step or set it appropriately. Hereinafter, a method for detecting or setting the end point of the first polishing step will be described.

  When the natural oxide film is completely polished and removed in the first polishing step, the surface property of the wafer changes, so that the frictional force between the wafer being polished and the polishing surface changes. That is, when the uppermost natural oxide film is polished, the polishing reaches the region of the metal film, and the difference in friction coefficient due to the difference in material causes a change in the frictional force between the wafer and the polished surface. Therefore, the end point of the first polishing step can be detected by detecting this frictional force. For example, when polishing a copper film with a normal slurry at a predetermined polishing pressure, after polishing and removing the natural oxide film, the entire surface of the copper film is covered with an insoluble complex. The friction force increases rapidly. Therefore, the end point of the first polishing process can be detected by detecting the change in the frictional force.

  Further, since the frictional force between the wafer and the polishing surface described above acts as a load torque on the rotating polishing table or top ring, the frictional force is detected by detecting the torque acting on the polishing table or top ring. Can be detected. When the polishing table or the top ring is rotationally driven by an electric motor, the torque can be measured as a current flowing through the motor. Therefore, the end point of the first polishing process can be detected by monitoring the current flowing through the motor with an ammeter.

  FIG. 6 is a schematic diagram showing a polishing unit that detects torque acting on the polishing table 300 to detect a frictional force between the wafer W being polished and the polishing surface 301. As shown in FIG. 6, the polishing unit includes an electric motor 302 that rotates the polishing table 300, and the polishing table 300 is rotated via a belt 303 by driving the motor 302. The motor 302 is connected to a current monitor 304 that detects the current of the motor 302 and performs signal processing. The current monitor 304 detects the current flowing through the motor 302 during polishing. By measuring this change in current, a change in torque of the polishing table 300, that is, a change in frictional force between the wafer W held on the top ring 305 and the polishing surface 301 is detected, and the first polishing step. The end point of can be detected.

Specifically, two-stage polishing is performed according to a flow as shown in FIG. When the first polishing process is started and the natural oxide film of the wafer W starts to be polished (S1), it is determined whether or not the current flowing through the motor 302 exceeds a preset current value I _max (threshold value) ( S2). This threshold value I _max may be input in advance by an operator, or may be set based on a database storing past data.

If the current value measured by the current monitor 304 does not exceed the threshold value I _max, the first polishing step is continued. On the other hand, if the current value exceeds the threshold value I _max , it is determined that it is the end point of the first polishing process, the second polishing process is started, and the metal film formed on the wafer W is polished. (S3). In this second polishing step, the film thickness of the wafer W being polished is measured by a film thickness measuring device (not shown) (S4), and this film thickness value is below a preset film thickness value T _limit (threshold). It is determined whether or not there is (S5). The threshold value T _limit may be input in advance by an operator, or may be set based on a database storing past data. When the measured film thickness value is larger than the threshold value T _limit , the second polishing process is continued, and when the current value becomes equal to or less than the threshold value T _limit , the second polishing process ends.

  In the example shown in FIG. 6, the torque (friction force) acting on the polishing table 300 is detected by detecting the current value of the motor 302 that rotates the polishing table 300, but the torque acting on the top ring 305 is measured. May be. Further, torque acting on each of the top ring 305 and the polishing table 300 may be measured. Further, instead of detecting the motor current, the frictional force generated between the top ring 305 and the polishing surface 301 on the polishing table 300 may be measured directly. In any case, an appropriate method can be selected according to the polishing conditions including the wafer W that is the object to be polished and the properties of the polishing liquid.

  FIG. 8 is a graph showing changes in the temperature of the polishing pad (polishing surface) and the motor current when the metal film is polished by lowering the polishing pressure after removing the natural oxide film with a high polishing pressure. The dotted line indicates the temperature of the polishing pad, and the solid line indicates the motor current. In the example shown in FIG. 8, the natural oxide film is removed by polishing at a polishing pressure P1 of 17.225 kPa (2.5 psi) as the first polishing step, and when the motor current increases, the polishing pressure P2 is set to 10.335 kPa ( 1.5 psi) and the process proceeds to the second polishing step. In this example, the polishing pressure P3 is further reduced to 6.89 kPa (1.0 psi).

  As shown in FIG. 8, after detecting a change in frictional force (change in motor current), the process may proceed immediately to the second polishing step. However, as shown in FIG. The first polishing step may be continued for a certain period of time after the change is detected, and then the second polishing step may be performed. The dishing amount in the example shown in FIG. 8 was 55 to 60 nm, and the dishing amount in the example shown in FIG. 9 was 85 to 90 nm.

  As another method for detecting the end point of the first polishing step, the film thickness of the wafer surface is measured using an eddy current sensor 400 as shown in FIG. 10, and the first polishing is performed from the measured film thickness. You may detect the end point of a process. The eddy current sensor 400 includes a sensor coil 401, an AC signal source 402 connected to the sensor coil 401, and a detection circuit 403 connected to the sensor coil 401 and the AC signal source 402. The sensor coil 401 is embedded in the polishing table and is disposed in the vicinity of the metal coating 404 including a natural oxide film on the wafer W.

  Such an eddy current sensor 400 supplies an alternating current signal to the sensor coil 401 from the alternating current signal source 402 to form an eddy current in the metal film 404 including the natural oxide film, and the eddy current is detected by the detection circuit 403. The impedance of the detected eddy current signal is divided into a resistance component and a reactance component, and the thickness of the metal film 404 on the surface of the wafer W is detected by measuring these displacements.

  Further, the end point of the first polishing step can be detected using an optical sensor as shown in FIG. The optical sensor shown in FIG. 11 includes a water ejection nozzle 501 that ejects a cylindrical water stream 500 toward the wafer W, a water tray 502 that receives the water stream 500 ejected from the water ejection nozzle 501, and an irradiation fiber 503. And a measurement calculation unit 505 having a light receiving fiber 504. The water ejection nozzle 501 and the water receiving tray 502 are formed in the polishing table 506. The distal ends of the irradiation fiber 503 and the light receiving fiber 504 of the measurement calculation unit 505 are arranged in the water ejection nozzle 501.

  A pressurized water flow 500 is supplied to the water ejection nozzle 501 via a water flow pipe 507, and a thin cylindrical water flow 500 is ejected from the tip of the water ejection nozzle 501 to the surface of the wafer W and held by the top ring 508. A measurement spot 509 is formed on the surface. In this state, light is sent from the measurement calculation unit 505 through the irradiation fiber 503 into the water flow 500, and this light is irradiated onto the measurement spot 509 of the wafer W through the water flow 500. The reflected light reflected by the measurement spot 509 is guided to the measurement calculation unit 505 through the water flow 500 and the light receiving fiber 504, and the measurement calculation unit 505 detects the film thickness of the wafer W based on the reflected light. According to such an optical sensor, since the slurry adhering to the surface of the wafer W is washed by the water flow 500, reflected light with less noise can be obtained.

  Here, the above-described monitor or sensor, such as the above-described current monitor and eddy current sensor, current monitor and optical sensor, eddy current sensor and optical sensor, or current monitor, eddy current sensor and optical sensor, is appropriately used. In combination, the end point of the first polishing step may be detected.

  The film thickness of the natural oxide film formed on the wafer increases in proportion to the waiting time of the wafer from the previous process to the polishing process. Although a plurality of wafers are stored in the wafer cassette, the wafers in the same wafer cassette have almost the same standby time. An oxide film is formed. Therefore, the time necessary for polishing and removing the natural oxide film for each wafer cassette may be set, that is, the end point of the first polishing process may be set.

  That is, as shown in FIG. 12, when the wafer cassette is carried into the polishing apparatus, the waiting time of the wafer from the previous process to the polishing process is acquired (S11). For example, when the polishing apparatus and the apparatus used in the previous process of the polishing apparatus are configured to be able to transmit information via a network and the wafer cassette is placed on the load / unload stage of the polishing apparatus, the discriminator The ID code assigned to the wafer cassette is read. Based on this ID code, data on the waiting time from the end of the previous process of the polishing apparatus until the wafer cassette is placed on the load / unload stage of the polishing apparatus is acquired via the network.

The control unit in the polishing apparatus calculates the natural oxide film thickness proportional to the standby time from the acquired wafer standby time (S12), and polishes and removes the natural oxide film based on the natural oxide film thickness. polishing time T ₁ is set from the relationship between the polishing rate required for (S13). The first polishing step is started, exceeds the natural oxide film of the wafer starts to be polished (S14), a polishing time T ₁ which is the set (S15), and, through the motor 302 (see FIG. 6) The first polishing process is continued until the current exceeds a preset current value I _max (threshold) (S16). Polishing time T ₁ is elapsed, the motor current exceeds the threshold value I _max, the second polishing step is started, the polishing is carried out of the metal film formed on the wafer (S17).

In the example shown in FIG. 12, elapsed polishing time T _1, and was continued first polishing step until the motor current exceeds the threshold value I _max, may be a flow as shown in FIG. 13. That is, the polishing time is first determined whether more than polishing time T ₁ (S18), starts a second polishing step if it exceeds (S17). If not exceed the polishing time T _1, it is determined whether the motor current exceeds the threshold value I _max (S19), if it exceeds initiates a second polishing step (S17), if not exceeded The first polishing process is continued. In this case, polishing time may be changed before and after the order of the determined determination of whether the motor current whether exceeds a polishing time T ₁ is greater than the threshold value I _max.

In the example shown in FIGS. 12 and 13, the film thickness of the natural oxide film is calculated based on the standby time from the previous process. However, as shown in FIGS. 14 and 15, the wafer is carried into the polishing apparatus. Then, for example, the film thickness of the natural oxide film is measured by a film thickness measuring instrument using Fourier Transform Infrared Spectrometer (FT-IR) (S20), and the polishing rate is calculated from the film thickness. It may be set the polishing time T ₁ required the natural oxide film to polish removed in relation (S21). The flow shown in FIGS. 14 and 15 may be performed for each wafer. However, as described above, a natural oxide film is formed on the wafer in the wafer cassette with substantially the same film thickness. Alternatively, the process may be performed on only the first wafer to be polished, only the first wafer to be polished from the beginning, or a certain number of wafers.

  Here, the substrate processing method described above can be applied not only to the polishing apparatus shown in FIGS. 1 and 4 but also to various substrate processing apparatuses. For example, the substrate processing method according to the present invention can be applied to a substrate processing apparatus configured as shown in FIG. The substrate processing apparatus shown in FIG. 16 includes three load / unload stages 600 on which a wafer cassette is placed. A travel mechanism 601 is provided along the load / unload stage 600, and a first transfer robot 602 having two hands is disposed on the travel mechanism 601. A film thickness measuring device 603 is arranged adjacent to the traveling mechanism 601. The hand of the first transfer robot 602 can access each wafer cassette and film thickness measuring device 603 on the load / unload stage 600.

  Further, the substrate processing apparatus shown in FIG. 16 includes four polishing units 604 to 607, and these polishing units 604 to 607 are arranged along the longitudinal direction of the apparatus. Each polishing unit includes a polishing table 608 having a polishing surface, a top ring 609 for holding the semiconductor wafer and polishing the semiconductor wafer while pressing the semiconductor wafer against the polishing table 608, and a polishing liquid or A polishing liquid supply nozzle 610 for supplying a dressing liquid (for example, water), a dresser 611 for dressing the polishing table 608, and a mixed fluid of liquid (for example, pure water) and gas (for example, nitrogen) in a mist form And an atomizer 622 that sprays the polishing surface from one or a plurality of nozzles.

  In the vicinity of the polishing units 604 and 605, a first linear transporter 612 that transports the wafer along the longitudinal direction is installed. On the load / unload stage 600 side of the first linear transporter 612, the first linear transporter 612 is disposed. A reversing device 613 for reversing the wafer received from the one transfer robot 602 is disposed. A second linear transporter 614 that transports the wafer along the longitudinal direction is also provided in the vicinity of the polishing units 606 and 607.

  The substrate processing apparatus also includes a second transfer robot 615, a reversing device 616 for reversing the wafer received from the second transport robot 615, four cleaning devices 617 to 620 for cleaning the polished semiconductor wafer, And a transfer unit 621 for transferring wafers between the cleaning machine 616 and the cleaning machines 617 to 620. The second transfer robot 615, the reversing machine 616, and the cleaning machines 617 to 620 are arranged in series along the longitudinal direction.

  In such a substrate processing apparatus, the wafers in the wafer cassette are introduced into the polishing units 604 to 607 via the reversing machine 613, the first linear transporter 612, and the second linear transporter 614. These polishing units 604 to 607 can perform the above-described substrate processing method. The polished wafer is introduced into the cleaning machines 617 to 620 via the second transfer robot 615 and the reversing machine 616, and is cleaned here. The cleaned wafer is returned to the wafer cassette by the first transfer robot 602.

  Moreover, although the example mentioned above demonstrated the case where the planarization unit which planarizes the metal film of a board | substrate was a chemical mechanical polishing unit which chemically mechanically polishes a metal film, it is not restricted to this. For example, instead of a chemical mechanical polishing unit, an electrolytic processing unit that performs electrolytic processing on a metal coating on a substrate using an electrolytic solution or ultrapure water, or a composite electrolytic processing that combines electrolytic processing and mechanical polishing is used as a substrate It is also possible to use a composite electrolytic processing unit for performing the metal coating.

  For example, if the above-described two-step polishing method is applied to electrolytic processing, the current or voltage in the first polishing step and the current or voltage in the second polishing step are changed as appropriate, so that the metal film formed on the wafer Since the metal film on the wafer can be removed with the natural oxide film removed, uniform planarization can be realized.

  FIG. 17 is a plan view showing an example of an electrolytic processing unit 700 that can be used in place of the above-described chemical mechanical polishing unit. The electrolytic processing unit 700 includes a circular electrode table 702 that can freely rotate (spin), and a processing electrode 706 including water supply nozzles 704 on both sides at a predetermined position along the circumferential direction of the electrode table 702. And the feeding electrodes 708 are alternately arranged. The processing electrode 706 and the power supply electrode 708 are connected to a power source (not shown).

  In such an electrolytic processing unit 700, pure water or ultrapure water is supplied from the water supply nozzle 704 while rotating the electrode table 702, and the electrode table 702 is moved to a position facing the wafer W by the rotation of the electrode table 702. The wafer W rotated as necessary is processed by the electrode 706 and the feeding electrode 708.

  18 is a plan view showing an example of a composite electrolytic processing unit 800 that can be used in place of the above-described chemical mechanical polishing unit, and FIG. 19 is a longitudinal sectional view of FIG. As shown in FIGS. 18 and 19, this composite electrolytic processing unit 800 includes an arm 802 that can move up and down and reciprocate along a horizontal plane, and is suspended from a free end of the arm 802 to form a surface (surface to be processed). ) Facing downward (face down), a wafer holder 804 that sucks and holds the wafer W, a movable frame 806 to which an arm 802 is attached, a rectangular processing table 808, and a power source 810 provided on the processing table 808. Yes. In the example shown in FIG. 18, the size of the processing table 808 is set to be slightly larger than the outer diameter of the wafer W held by the wafer holder 804.

  A vertical movement motor 812 is installed on the upper part of the movable frame 806, and a ball screw 814 extending in the vertical direction is connected to the vertical movement motor 812. A base 802 a of an arm 802 is attached to the ball screw 814, and the arm 802 moves up and down via the ball screw 814 as the vertical movement motor 812 is driven. The movable frame 806 itself is also attached to a ball screw 816 extending in the horizontal direction, and the movable frame 806 and the arm 802 reciprocate along a horizontal plane as the reciprocating motor 818 is driven.

  The wafer holder 804 is connected to a rotation motor 820 installed at the free end of the arm 802, and can rotate (spin) as the rotation motor 820 is driven. Further, as described above, the arm 802 can move up and down and reciprocate in the horizontal direction, and the wafer holder 804 can move up and down and reciprocate in the horizontal direction integrally with the arm 802.

  A hollow motor 822 is installed below the processing table 808, and a drive end 826 is provided on the main shaft 824 of the hollow motor 822 at a position eccentric from the center of the main shaft 824. The processing table 808 is rotatably connected to the drive end 826 through a bearing (not shown) at the center thereof. Further, three or more rotation prevention mechanisms (not shown) are provided in the circumferential direction between the processing table 808 and the hollow motor 822. By these anti-rotation mechanisms, the machining table 808 performs a scrolling motion (translational rotational motion) by driving the hollow motor 822.

  As shown in FIG. 18, the processing table 808 includes a plurality of mechanical processing portions 830 made of, for example, fixed abrasive grains, and a plurality of processing electrodes 832 and power supply electrodes 834 that constitute an electrolytic processing portion. As shown in FIG. 19, the processing table 808 includes a flat base 836, and a plurality of processing electrodes 832 extending along the X direction (see FIG. 18) and power supply electrodes are provided on the upper surface of the base 836. 834 are alternately arranged at predetermined intervals. These processing electrode 832 and power supply electrode 834 are connected to a power source 810. A plurality of mechanically processed portions 830 extending along the X direction (see FIG. 18) are arranged on both sides of the power supply electrode 834 sandwiching the processed electrode 832. The upper surface of each processing electrode 832 is covered with an ion exchanger 838 having a semicircular cross section.

  Then, a predetermined voltage is applied between the processing electrode 832 and the power supply electrode 834 by the power source 810, and the wafer W is formed on the processing electrode (cathode) 832 by hydrogen ions or hydroxide ions generated by the ion exchanger 838. Electrolytic processing is performed on the conductor film on the surface. At this time, processing proceeds at a portion facing the processing electrode 832, but processing of the entire surface of the wafer W is performed by relatively moving the wafer W and the processing electrode 832. At the same time, the mechanically processed portion 830 is rubbed against the surface of the wafer W, thereby mechanically processing the conductor film on the surface of the wafer W in the presence of pure water or ultrapure water.

  Although one embodiment of the present invention has been described so far, it is needless to say that the present invention is not limited to the above-described embodiment, and may be implemented in various forms within the scope of the technical idea.

It is a top view which shows the grinding | polishing apparatus as a substrate processing apparatus in the 1st Embodiment of this invention. It is a longitudinal cross-sectional view which shows the wet etching unit in the grinding | polishing apparatus of FIG. It is a longitudinal cross-sectional view which shows the top ring which can change the pressing force with respect to a wafer for every area | region. It is a top view which shows the grinding | polishing apparatus as a substrate processing apparatus in the 2nd Embodiment of this invention. It is a graph which shows the effect at the time of performing a water supply process in the polish method concerning the present invention. It is a schematic diagram which shows the grinding | polishing unit which detects the torque which acts on a grinding | polishing table, and detects the frictional force between the wafer in grinding | polishing, and a grinding surface. It is a flowchart which shows an example of the grinding | polishing method which concerns on this invention. It is a graph which shows the temperature of a polishing pad at the time of performing the polish method concerning the present invention, and change of motor current. It is a graph which shows the temperature of a polishing pad at the time of performing the polish method concerning the present invention, and change of motor current. It is a schematic diagram which shows the structure of the eddy current sensor which measures the film thickness of the surface of a wafer using an eddy current. It is a schematic diagram which shows the grinding | polishing unit provided with the optical sensor which measures the film thickness of the surface of a wafer. It is a flowchart which shows an example of the grinding | polishing method which concerns on this invention. It is a flowchart which shows an example of the grinding | polishing method which concerns on this invention. It is a flowchart which shows an example of the grinding | polishing method which concerns on this invention. It is a flowchart which shows an example of the grinding | polishing method which concerns on this invention. It is a top view which shows the grinding | polishing apparatus as a substrate processing apparatus in the 3rd Embodiment of this invention. It is a top view which shows an example of the electrolytic processing unit of the substrate processing apparatus in the 4th Embodiment of this invention. It is a top view which shows an example of the composite electrolytic processing unit of the substrate processing apparatus in the 5th Embodiment of this invention. It is a longitudinal cross-sectional view of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Wafer cassette 2 Load / unload stage 3 Traveling mechanism 4,201 1st transfer robot 5,6,212,213 Washing / drying machine 7,8,9,10,202,203 Mounting table 11 Wafer station 12,205 First 2 transfer robots 13, 207 3rd transfer robot 14 Wet etching units 15, 215, 216 Cleaning machines 16, 17, 223, 224 Polishing units 18, 19, 24, 25, 225, 228, 300 Polishing tables 20, 26, 226 , 229, 305 Top ring 21, 27 Polishing liquid supply nozzle 22, 23, 28, 29 Dresser 30, 31, 219, 220 Inverter 32 Rotary transporter 33, 34 Lifter 35, 36, 227, 230 Pusher 100 Film thickness measurement 140 Cylinder 141 Bearing 142 Rotation drive 143 Chuck parts 144, 146 Pulley 145 Belt 147 Motor 148 Chemical / pure water nozzle 204 Vacuum chamber 206 Dry etching unit 210 Vacuum pump 211 Fourth transfer robot 217 Fifth transfer robot 218 Sixth transfer robot 221, 222 Transporter 235 Process gas Supply device 302 Motor 304 Current monitor 700 Electrolytic machining unit 800 Composite electrolytic machining unit

Claims (15)

Removing the natural oxide film of the metal formed on the surface of the metal film on the substrate;
A substrate processing method, comprising: planarizing a metal film on the substrate after the removing process.   2. The substrate processing method according to claim 1, wherein the removing process is a wet process using a chemical solution capable of dissolving the metal natural oxide film.   2. The substrate processing method according to claim 1, wherein the removing process is a dry process using a gas capable of reducing or etching the natural oxide film of the metal.   The substrate according to any one of claims 1 to 3, wherein the planarization treatment is any one of chemical mechanical polishing, electrolytic processing, and composite electrolytic processing in which electrolytic processing and mechanical polishing are combined. Processing method. A polishing method for polishing a metal film by pressing a substrate having a metal film formed on a surface against a polishing surface,
A first polishing step for removing at least a natural oxide film of the metal formed on the metal film on the substrate by polishing;
A second polishing step for removing the metal film of the substrate by polishing;
A polishing method characterized by comprising: The first polishing step includes a step of polishing the substrate by pressing the substrate against the polishing surface with a first pressure,
The said 2nd grinding | polishing process includes the process of pressing the said board | substrate to the said grinding | polishing surface with the 2nd pressure different from the said 1st pressure, and grind | polishing this board | substrate. Polishing method.   The polishing method according to claim 6, wherein the first pressure is larger than the second pressure. The first polishing step includes a step of polishing the substrate by pressing the substrate against the polishing surface while supplying a first polishing liquid to the polishing surface;
The second polishing step includes a step of polishing the substrate by pressing the substrate against the polishing surface while supplying a second polishing solution different from the first polishing solution to the polishing surface. The polishing method according to claim 5.   6. A water supply step of pressing the substrate against the polishing surface while supplying water to the polishing surface between the first polishing step and the second polishing step. The polishing method according to claim 8.   10. The polishing method according to claim 5, wherein the end of the first polishing step is detected based on a frictional force between the substrate and the polishing surface. 11. A polishing method for polishing a metal film by pressing a substrate having a metal film formed on a surface against a polishing surface,
A first polishing step of polishing the substrate by pressing the substrate against the polishing surface with a first pressure;
A water supply step of pressing the substrate against the polishing surface while supplying water to the polishing surface after the first polishing step;
A second polishing step of polishing the substrate by pressing the substrate against the polishing surface with a second pressure greater than the first pressure after the water supply step;
A polishing method characterized by comprising: A processing unit for removing a natural oxide film of the metal formed on the surface of the metal film on the substrate;
A flattening unit for flattening the metal film on the substrate;
A substrate processing apparatus comprising:   The substrate processing apparatus according to claim 12, wherein the processing unit is a wet processing unit that performs a wet process using a chemical solution capable of dissolving the natural oxide film of the metal.   The substrate processing apparatus according to claim 12, wherein the processing unit is a dry processing unit that performs a dry process using a gas capable of reducing or etching the natural oxide film of the metal.   The flattening unit includes a chemical mechanical polishing unit that chemically and mechanically polishes the metal coating on the substrate, an electrolytic processing unit that performs electrolytic processing on the metal coating on the substrate, and a composite electrolytic processing that combines electrolytic processing and mechanical polishing. The substrate processing apparatus according to any one of claims 12 to 14, wherein the substrate processing apparatus is any one of a complex electrolytic processing unit that performs the processing on the metal film of the substrate.

Images