JP2005311127A - Liquid used for cmp method and manufacturing method of semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide liquid used for a CMP method which effectively cleans a polisher and a wafer in a polishing process by the CMP method and a process to clean the polisher, and to provide the manufacturing method of a semiconductor device including the effective cleaning process. <P>SOLUTION: The liquid which is used in the polishing process using the CMP method or used in processes before and after the process, and which cleans, or rinses after cleaning is constituted by a component obtained by removing an abrasive grain component from polishing slurry used in the polishing process. A polishing head, a wafer surface or the like used in the polishing process are cleaned using the liquid. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a liquid used in a polishing process using a CMP (Chemical Mechanical Polishing) method and a method for manufacturing a semiconductor device including a polishing process using a CMP method.

  Polishing using a CMP method is performed in a manufacturing process of a semiconductor device. The process using the CMP method can be divided into a polishing process for polishing the wafer and a cleaning process for cleaning the polished wafer. Further, the polishing step can be divided into polishing cloth conditioning, wafer polishing and polishing cloth cleaning.

  Conditioning of the polishing cloth is performed for the purpose of adjusting the condition of the surface of the polishing cloth, but conventional conditioning is performed while supplying pure water. As a result, polishing scraps and residual slurry generated during polishing of the wafer are removed simultaneously with the sharpening of the polishing cloth surface.

  The polishing cloth cleaning is conventionally performed by supplying pure water from the pure water supply line or the pure water supply spray onto the polishing cloth.

  In the polishing process, the polishing head and the wafer are cleaned every time the polishing of the wafer is completed. Conventional cleaning is performed by spraying pure water with a shower nozzle or the like. In the case of pure water, when the detergency is not sufficient, a cleaning chemical such as a water-soluble surfactant may be used instead of the pure water.

  Furthermore, after the polishing process is completed, it is necessary to clean the polishing apparatus used in the CMP method. The conventional polishing apparatus is cleaned using pure water. In addition, when the detergency is insufficient with pure water, a cleaning chemical may be used.

  When the polishing cloth and the polishing head are not sufficiently cleaned, foreign matters such as polishing dust, slurry, and a complex composed of the object to be polished and the slurry remain on the surface of the polishing cloth, the polishing head, and the wafer. If this foreign matter remains, there is a risk that a micro-scratch called a micro scratch will occur on the surface of the wafer 14. In addition, the adhesion of these foreign substances may cause a decrease in yield. Therefore, it is necessary to carefully clean the polishing cloth, the polishing head and the wafer as described above.

Patent Document 1 (Japanese Patent Laid-Open No. 2001-138211) discloses such a CMP method and an apparatus used therefor.
JP 2001-138211 A

  In the conventional polishing process, in the cleaning of the polishing head and the wafer immediately after the wafer polishing, pure water is used, so that it takes a long time to remove the residue. Further, when the cleaning chemical solution is used, the cleaning time can be shortened, but the components of the cleaning chemical solution are brought into the surface of the polishing cloth being polished, which may adversely affect the polishing characteristics.

  Also, the cleaning of the polishing apparatus after the polishing process is completed requires a long time because pure water is used. Further, when the cleaning chemical is used, there is a possibility that the polishing characteristics are adversely affected as in the case described above.

  On the other hand, in the conditioning of the polishing cloth in the conventional CMP method, the removal of the residual slurry, polishing debris and complexes on the surface of the polishing cloth was incomplete. Therefore, the surface of the polishing pad must be scraped off more than necessary, and the polishing pad needs to be conditioned for a long time under high pressure and high rotation, resulting in a problem that the life of the polishing pad and the conditioner is shortened.

  Accordingly, the present invention has been made to solve the above-described problems, and a CMP method capable of efficiently cleaning a polishing apparatus and a wafer in a polishing process by a CMP method and a process of cleaning a polishing apparatus. It is a first object of the present invention to provide a method for manufacturing a semiconductor device including a liquid used in the above-described process and a process capable of efficient cleaning.

  Furthermore, a second object of the present invention is to provide a method for manufacturing a semiconductor device capable of extending the maintenance cycle by effectively conditioning the polishing pad.

  According to the liquid used in the CMP method according to the present invention, the liquid used in the polishing step using the CMP method or a process before and after the polishing method is used for cleaning or rinsing after the cleaning. This is a component obtained by removing the abrasive component from the polishing slurry to be used.

  According to one aspect of the semiconductor device manufacturing method based on the present invention, a semiconductor device manufacturing method including a polishing process using a CMP method, wherein the polishing process is performed immediately after completion of wafer polishing. The process includes a step of cleaning the polishing head and the wafer surface used in the above with a liquid, and a liquid having a component obtained by removing abrasive components from the polishing slurry used in the polishing process is used as the liquid.

  According to another aspect of the method for manufacturing a semiconductor device according to the present invention, a method for manufacturing a semiconductor device comprising a polishing process using a CMP method, which is used in the polishing process after the polishing process is completed. The method further includes a step of cleaning the polishing table and the polishing head using a liquid, and a liquid having a component obtained by removing abrasive components from the polishing slurry used in the polishing step is used as the liquid.

  According to another aspect of the method for manufacturing a semiconductor device according to the present invention, a method for manufacturing a semiconductor device comprising a polishing process using a CMP method, which is used in the polishing process after the polishing process is completed. The method further includes a step of cleaning the polishing table and the polishing head, wherein the step includes a step of cleaning the polishing table and the polishing head using a cleaning liquid, and a liquid having a component obtained by removing the abrasive components from the polishing slurry used in the polishing step. And rinsing the polishing table and the polishing head after cleaning.

  According to another aspect of the semiconductor device manufacturing method according to the present invention, a semiconductor device manufacturing method including a polishing process using a CMP method, wherein the polishing cloth is used during conditioning of the polishing cloth used in the polishing process. An aqueous solution containing a thickener is supplied between the container and the conditioner.

  First, before describing in detail embodiments related to each step of a method of manufacturing a semiconductor device including polishing using a CMP method, a polishing method and a polishing apparatus using the CMP method common to each embodiment will be described. explain.

  The polishing process by the CMP method is performed by the procedure of conditioning the polishing cloth 3 using the conditioner 1, polishing the wafer 14, cleaning the polishing cloth 3, and cleaning the wafer and the polishing head immediately after polishing. This polishing process is sequentially repeated to polish a plurality of wafers 14. The wafer 14 polished in the polishing process is cleaned in the cleaning process.

  FIG. 1 is a perspective view showing a condition of the polishing cloth. As shown in FIG. 1, the polishing apparatus used for the CMP method in a state where the polishing cloth 3 is conditioned, a disk-shaped polishing surface plate 2, a polishing cloth 3 provided on the upper surface thereof, and the polishing cloth 3 A conditioner 1 that rotates while contacting the surface, and a liquid supply line 6 that supplies liquid to the surface of the polishing pad 3 to the polishing pad 3 are provided. A slurry supply line 5 also exists above the polishing surface plate 2 but is not used in this step.

  The conditioner 1 is rotating at a predetermined rotation speed, for example, 80 to 130 rpm. The polishing surface plate 2 is also rotated at a predetermined rotational speed, for example, 60 to 130 rpm. The polishing surface plate 2 and the polishing cloth 3 are bonded. Conditioning is performed by pressing the conditioner 1 against the polishing pad 3 with a predetermined load, for example, 50 to 350 N while supplying the liquid from the liquid supply line 6.

  When conditioning is completed, the wafer 14 is polished. FIG. 2 is a perspective view showing a process of polishing the wafer. As shown in FIG. 2, the conditioner 1 is retracted from the polishing cloth 3 in the step of polishing the wafer 14. Instead of the conditioner 1, a polishing head 4 is positioned on the polishing pad 3.

  The polishing head 4 holds a wafer 14 to be polished on its lower surface, and rotates at a predetermined rotation speed, for example, 30 to 130 rpm. While supplying the slurry 8 from the slurry supply line 5, the polishing head 4 presses the wafer 14 against the polishing pad 3 at a predetermined pressure, for example, 20 to 50 kPa, thereby polishing the wafer 14.

  When polishing of the wafer 14 is completed, the process proceeds to a polishing cloth cleaning process. FIG. 3 is a perspective view showing a polishing cloth cleaning step. As shown in FIG. 3, the polishing head 4 is retracted from the polishing cloth 3 in the polishing cloth cleaning step. In the polishing cloth cleaning step, the polishing surface plate 2 is rotated at a predetermined rotational speed, for example, 20 to 50 rpm. The polishing cloth 3 is washed by supplying liquid from the liquid supply line 6 or the liquid supply spray 7 onto the polishing cloth 3.

  In addition, the polishing head and the wafer immediately after the polishing of the wafer 14 are cleaned by spraying a liquid on them using a shower nozzle or the like.

  The above polishing process is called a pre-conditioning method. A polishing process called a post-conditioning method in which the conditioning shown in FIG. 1 and the wafer polishing process shown in FIG. 2 are reversed may be employed.

  FIG. 4 is a plan view showing the CMP apparatus. In FIG. 4, a polishing process is performed in the polishing chamber 9, and a cleaning process for cleaning the wafer 14 in the cleaning unit 12 is performed. The transfer robot 11 transfers the wafer 14 set in the cassette port 13 to the polishing chamber 9 and the cleaning unit 12.

(Embodiment 1)
Next, the first embodiment will be described. The first embodiment relates to the conditioning of the polishing pad 3.

  In the conditioning of the polishing pad 3 shown in FIG. 1, as described above, the conditioning is conventionally performed while supplying pure water to the polishing pad 3. Therefore, in order to sufficiently remove deposits such as residual slurry and reaction products, it is necessary to perform conditioning for a long time with a high load.

  In such conventional conditioning, the resin itself, which is an abrasive cloth material, is scraped to remove the deposits. For this reason, not only does the conditioning take time, but also the amount of the polishing cloth 3 to be scraped increases, resulting in a problem that the life of the polishing cloth 3 is shortened. In addition, the conditioner itself has a short life.

  FIG. 6 shows a cross section of the conditioner. As shown in FIG. 6, the conditioner 1 has a disk-shaped conditioner washer 20 and diamond grains 21 fixed below the Ni plating electrodeposition layer 20. In conditioning, the diamond grains 21 embedded in the surface of the conditioner 1 rub the surface of the polishing pad 3. At this time, an excessively large load is locally applied due to the unevenness of the surface of the polishing pad 3, and uneven wear of the diamond grains 21, dropping off of the diamond grains 21, and the like occur. Therefore, such a local load is not preferable. The life of the polishing pad 3 and the life of the conditioner 1 can be extended by relaxing the local load that damages the diamond grains 21 while applying a load that can maintain the removal rate and the polishing rate. .

  Based on such knowledge, as a result of repeated studies by the inventors, an additive that reduces the frictional force between the conditioner 1 and the surface of the polishing pad 3 during conditioning of the polishing pad 3 has been conventionally used. It was revealed that the above local overload can be alleviated by adding to pure water.

  By using various thickeners as such additives, ideal conditioning can be realized. As this thickener, various water-soluble polymers can be used. It is not always clear how the effect of adding a water-soluble polymer is manifested, but a liquid film tends to remain between the polishing cloth 3 and the conditioner 1 during conditioning due to thickening of water. It is presumed that the deposit removal performance is improved while suppressing damage to the conditioner 1. In addition, it is considered that the effect of reducing the frictional force is also exerted by the water-soluble polymer adsorbed on the surface of the polishing pad 3.

  Thickeners that can be used in conditioning include, but are not limited to, cellulose polymers such as ethyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, nitrocellulose, and cationized cellulose, alginic acid Salts, alginate polymers such as propylene glycol alginate, polyacrylates, carboxy vinyl polymers, acrylic polymers such as polyacrylate amides and copolymers thereof, vinyl such as vinyl pyrrolidone, vinyl alcohol, vinyl acetate Monomers and copolymers, polyethylene glycol and copolymers thereof, and the like.

  The addition amount of these thickeners is desirably 0.1% by weight or more and 15% by weight or less, and more desirably 0.3% by weight or more and 5% by weight or less. When the addition amount is too small, a sufficient addition effect cannot be obtained, and when the addition amount is too large, sufficient conditioning cannot be performed. However, even if the added amount is less than 0.1% by weight or exceeds 15% by weight, some effect can be expected.

  As a thickener to be added, in addition to water-soluble polymers, quaternary ammonium salts of various alkylamines such as tetramethylammonium hydroxide, acids such as sulfuric acid, acetic acid and phenol, and salts thereof such as ammonium sulfate may be used. Good.

  Conditioning is performed while flowing an aqueous solution containing the above additives. If the additive remains on the polishing cloth 3 and there is a possibility that the abrasive particles of the polishing slurry are falsely collected or the function of the components contained in the polishing slurry may be hindered, after the conditioning, Wash the polishing cloth 3 with water or the like. In many cases, washing with pure water is sufficient, but when an acid or alkali is added, a solution for neutralizing them may be used. Further, a more preferable result may be obtained by using a technique such as adding a dispersant contained in the slurry at the time of washing after conditioning so that the polishing is not affected by neutralization.

  In the conventional conditioning, it was necessary to carry out the conditions under high rotation, high pressure, and long time for removing polishing debris, reaction products, and residual slurry on the polishing cloth 3, but the thickener was added. Due to the effect, these conditions are not necessary, so that the conditioning time can be shortened and the life of the polishing pad 3 and the conditioner 1 can be extended.

(Embodiment 2)
Next, a second embodiment will be described. The second embodiment relates to the cleaning of the polishing head 4 and the wafer 14 performed before and after the polishing of the wafer 14.

  The cleaning of the polishing head 4 and the surface of the wafer 14 before and after the polishing of the wafer 14 is performed by spraying liquid onto these using a spray nozzle 16 as shown in FIG. A pipe is connected to the spray nozzle 16 via a liquid valve 17 and a chemical liquid valve 18. A transfer arm 15 is provided below the polishing head.

  As described above, pure water has been conventionally used as the liquid. However, since this cleaning method may not have a sufficient cleaning effect, a cleaning chemical solution (for example, a water-soluble surfactant, alkaline) may be used instead of pure water. The surface of the polishing head may be cleaned by 10 times dilution). When such a chemical solution is used, it becomes possible to remove the slurry and other deposits adhering to the surface of the polishing head more effectively and in a shorter time as compared with pure water jet alone. However, in the method performed using the cleaning chemical solution, there is a possibility that the components of the cleaning chemical solution are brought into the surface of the polishing cloth being polished and affect the polishing characteristics.

  In this embodiment, in order to avoid such a problem, the surface of the polishing head 4 and the wafer 14 is cleaned using a liquid of a component obtained by removing the abrasive component from the slurry used for polishing the wafer 14. Thereby, the number of foreign substances adhering to these is reduced. About the temperature of this liquid, although it is normal to carry out at normal temperature, a cleaning effect can be improved further by heating up to about 30-60 degreeC.

  The liquid from which the abrasive grain component has been removed from the slurry may be prepared separately from the beginning, or may be used after removing only the abrasive grains from the polishing slurry. If the latter method is used, there is an effect that supply equipment for another type of chemical solution is not necessary. Various methods can be used as a method for removing abrasive grains from the polishing slurry, and a precision membrane filtration (MF) method, an ultrafiltration (UF) method, or the like can be used.

  Further, it is also effective to use the liquid from which the abrasive grain component is removed from the slurry at the time of water polishing immediately after polishing. As shown in FIG. 2, during polishing, slurry is supplied from the slurry supply line 5, and when a certain amount of polishing is reached, supply from the slurry supply line 5 is stopped and polishing is performed while supplying liquid from the liquid supply line 6. By doing so, the surface of the wafer 14 is pre-cleaned.

  Conventionally, pure water is used as this liquid, but agglomeration of abrasive grains due to rapid pH fluctuations can be prevented by using a liquid obtained by removing abrasive grain components from a slurry instead of pure water. In addition, since the liquid from which the abrasive grain component is removed from the slurry has excellent dispersibility of the abrasive grains, the surface of the polishing head 4 and the wafer 14 can be effectively cleaned. Similarly, at the time of cleaning the polishing cloth 3 shown in FIG. 3 and the conditioning shown in FIG. 1, by using a liquid from which the abrasive grain components have been removed from the slurry instead of pure water from the nozzle, Foreign matter remaining on the surface of the polishing pad 3 can be effectively removed.

(Embodiment 3)
This embodiment is an embodiment relating to cleaning of a polishing apparatus that is performed after a series of polishing steps is completed.

  After the polishing process is completed, it is necessary to clean the polishing apparatus. As described above, the polishing apparatus includes the polishing head 4, the polishing cloth 3, the polishing surface plate 2, the conditioner 1, and the like. The polishing apparatus further includes a drain pipe for discharging the used slurry and cleaning liquid, and a drain receiver. After completion of the polishing process, it is necessary to clean these portions of the polishing apparatus as necessary.

  For example, drainage pipes and drainage receptacles are conventionally cleaned while jetting pure water, but pure water may not provide a sufficient cleaning effect. A method of cleaning with a cleaning chemical instead of pure water is also conceivable. However, in this method, if the cleaning chemical is mixed on the polishing surface plate, the polishing characteristics may be adversely affected.

  In the present embodiment, as a method for solving such a problem, by using a liquid from which only the abrasive grain components are removed from the slurry, abrasive grains which aggregate due to various factors such as contamination and drying and exhibit an undesirable effect are obtained. Cleaning and removing. According to this method, even if the cleaning liquid remains on the polishing pad 3, there is no adverse effect on polishing. In addition, since the slurry contains an abrasive dispersant and the like, the slurry is excellent in the removal effect of the slurry pseudo-collection, which often causes a problem.

  Further, instead of the above method, there is also a method of performing rinsing with a liquid obtained by removing only the abrasive components from the slurry after performing the above cleaning using various cleaning chemicals. If this method is used, it is possible to reduce the influence of various cleaning chemicals on polishing.

Various methods can be used as a method for removing abrasive grains from the polishing slurry, and a precision membrane filtration (MF) method, an ultrafiltration (UF) method, or the like can be used. As the various cleaning chemicals, acid or alkali, other various surfactants, and combinations thereof can be used.

  The cleaning performed with the liquid from which the abrasive grains have been removed from the slurry can also be performed by spraying for 30 seconds at an arbitrary interval, for example, once every 15 minutes, during the standby time when polishing is not performed. Compared to the case of conventional pure water injection alone, it is possible to remove deposits more effectively and in a short time. When similar cleaning is performed using various cleaning chemicals, rinsing with a liquid from which abrasive grains have been removed from the slurry is performed for several seconds.

  The temperature of the cleaning liquid is usually room temperature, but it is possible to more effectively clean the drain receiver by raising the temperature to about 30 to 60 ° C. By using the chemical solution in the cleaning line, the number of periodic cleanings in the drain receiver, drain pipe, and housing is reduced.

  In addition, the said embodiment disclosed this time is an illustration in all the points, Comprising: It does not become the basis of limited interpretation. Therefore, the technical scope of the present invention is not interpreted only by the above-described embodiments, but is defined based on the description of the claims. Further, all modifications within the meaning and scope equivalent to the scope of the claims are included.

It is a perspective view which shows the state of conditioning of polishing cloth. It is a perspective view which shows the process of grind | polishing a wafer. It is a perspective view which shows an abrasive cloth washing | cleaning process. It is a top view which shows a CMP apparatus. It is a perspective view which shows a spray nozzle. It is a longitudinal cross-sectional view which shows a conditioner.

Explanation of symbols

  1 conditioner, 2 polishing surface plate, 3 polishing cloth, 4 polishing head, 5 slurry supply line, 6 liquid supply line, 7 liquid supply spray, 8 slurry, 14 wafer, 16 spray nozzle.

Claims (5)

A liquid that is used in a polishing process using CMP (Chemical Mechanical Polishing) method or a process before and after the polishing process, and that performs cleaning or rinsing after cleaning,
The liquid is a liquid used in a CMP method, which is a component obtained by removing abrasive components from a polishing slurry used in a polishing process. A method for manufacturing a semiconductor device comprising a polishing process using a CMP method,
The polishing step includes a step of cleaning the polishing head and the wafer surface used in the polishing step with a liquid immediately after completion of polishing of the wafer,
A method for manufacturing a semiconductor device, wherein a liquid having a component obtained by removing an abrasive grain component from a polishing slurry used in the polishing step is used as the liquid. A method for manufacturing a semiconductor device comprising a polishing process using a CMP method,
After the polishing step is completed, the method further comprises a step of cleaning the polishing table and the polishing head used in the polishing step with a liquid,
A method for manufacturing a semiconductor device, wherein a liquid having a component obtained by removing an abrasive grain component from a polishing slurry used in the polishing step is used as the liquid. A method for manufacturing a semiconductor device comprising a polishing process using a CMP method,
After the polishing step is completed, the method further comprises a step of cleaning the polishing table and the polishing head used in the polishing step,
The steps include washing the polishing table and the polishing head using a cleaning liquid, and rinsing the cleaned polishing table and the polishing head using a liquid having a component obtained by removing abrasive components from the polishing slurry used in the polishing step. A method for manufacturing a semiconductor device. A method for manufacturing a semiconductor device comprising a polishing process using a CMP method,
A method of manufacturing a semiconductor device, wherein an aqueous solution containing a thickener is supplied between the polishing cloth and a conditioner during conditioning of the polishing cloth used in the polishing step.

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