Abstract:
A method for manufacturing a semiconductor and an apparatus for measuring slurry quality. The apparatus includes a plurality of slurry supply devices, a plurality of semiconductor processing devices, and an in-line monitoring system. The slurry supply devices have slurry supply lines. The semiconductor processing devices receive slurry from each of the slurry supply devices through the slurry supplying lines to perform semiconductor processing. The in-line monitoring system includes a plurality of sampling lines diverging from the plurality of slurry supplying lines. The particle sizes of the slurry are measured through each of the sampling lines. The monitoring system maintains the slurry quality in real time to increase yield from CMP (chemical-mechanical polishing).

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This U.S. non-provisional patent application claims priority under 35 U.S.C. §119 of Korean Patent Application No. 2006-57699, filed on Jun. 26, 2006, the entire contents of which are hereby incorporated by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    The present invention disclosed herein relates to an apparatus for manufacturing semiconductors and a method for measuring the quality of a slurry, and more particularly, to an apparatus for manufacturing semiconductors and a method for measuring the quality of a slurry that are capable of reducing defects of chemical-mechanical polishing. 
         [0003]    Due to today&#39;s demands for increasingly high integration and density in the semiconductor industry, techniques for forming finer patterns are being used, and fields requiring multi-level wiring structures are increasing. Accordingly, semiconductor device structures are becoming more complex. An example of this complexity is the increased severity of stepped degrees of interlayer films. 
         [0004]    Severe stepping of interlayer films may generate process defects during semiconductor manufacturing. To remove such defects, techniques such as SOG, etch back, reflow, and chemical-mechanical polishing (CMP) for regional planarization have been developed. In a CMP process, the removal rate and uniformity are crucial factors, along with slurry type, polishing pad type, and so on. 
         [0005]    Slurry, which mechanically forces polishing compounds onto the surface of a wafer, generally consists of polishing particles, ultra-pure water, and additives. Slurries use physical, chemical, and mechanical principles involving agglomerations of particles. CMP using agglomerated slurry particles produces defects on the surface of the wafer, such as micro scratches, reducing production yield. These defects are known to be caused by the inclusion of undesirable particles that are excessively large (or coarse). 
         [0006]    Coarse particles may form in slurry from smaller particles agglomerating. This is a phenomenon that continues to occur even after the slurry is correctly manufactured. Agglomerating particles are due to the constant motion of all particles within the slurry after its manufacture. Thus, performing CMP has always involved large drawbacks. There is always the possibility of introducing a new slurry that has already agglomerated, perhaps during the transport and supply stage. In addition, many external factors such as temperature, outside impurities, aging, and so on can deteriorate the quality of slurry. Comprehensive examinations of micro-scratch occurrences (one of the major defects that can arise in a CMP process) show that coarse particles from various sources (approx. 1 μm or larger) are among the principle causes. 
       SUMMARY OF THE INVENTION 
       [0007]    The present invention provides a solution to these problems by monitoring the degree of coarse particle formation on slurry supply equipment, preferably in real time, in order to maintain slurry quality and prevent the introduction of low-quality slurry. 
         [0008]    An embodiment of the present invention provides a semiconductor manufacturing apparatus and a method of measuring quality of slurry. The apparatus and method are capable of managing the quality of slurry and reducing defects during a chemical-mechanical polishing process. 
         [0009]    To achieve these objects of the present invention, there are provided semiconductor manufacturing apparatuses and methods for measuring the quality of the slurry that include a slurry quality monitoring system connected in-line to a plurality of slurry supply devices to monitor the quality of the slurry in real time. 
         [0010]    In an embodiment, an apparatus for manufacturing a semiconductor may comprise: a plurality of slurry supply devices each having a slurry supply line; a plurality of semiconductor processing devices for receiving slurry from each of the slurry supply devices through the slurry supply line; and an in-line monitoring system including a plurality of sampling lines connected to the plurality of slurry supply lines, the in-line monitoring system configured to measure particle sizes of the slurry. The in-line monitoring system may comprise a particle size analyzer for diluting the slurry and measuring the number and sizes of slurry particles. 
         [0011]    In another embodiment the particle size analyzer may comprise: a diluting device for diluting the slurry with a diluent; a sample loop for mixing the slurry with the diluent; a pump for generating a predetermined pressure to provide the diluent to the sample loop at a predetermined flow rate; and a sensor for receiving diluted slurry from the diluting device and measuring the number and sizes of the slurry particles. 
         [0012]    In still another embodiment, a method for measuring slurry quality may comprise: supplying slurry from a plurality of slurry supply devices to a plurality of semiconductor processing devices through a plurality of slurry supply lines; providing the supplied slurry to a particle size analyzer through a sampling line connected to one of the slurry supplying lines; and diluting the slurry provided to the particle size analyzer to measure slurry particle sizes. 
         [0013]    The method may further comprise: cleaning the sampling line by providing a cleaning solution to the sampling line while not providing the slurry to the sampling line; and providing the cleaning solution to the particle size analyzer to measure the number and sizes of the slurry particles mixed with the cleaning solution. 
         [0014]    In yet another embodiment, measuring the particle sizes of the slurry may comprise: providing the slurry to a sample loop to mix deionized water with the slurry provided to the sample loop; providing the slurry mixed with the deionized water to a diluting device; diluting the slurry; and providing the diluted slurry to an optical sensor to measure the number and sizes of the slurry particles. 
     
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0015]    The accompanying figures are included to provide a further understanding of the present invention, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present invention and, together with the description, serve to explain principles of the present invention. In the figures: 
           [0016]      FIG. 1  is a schematic block diagram of a semiconductor manufacturing apparatus illustrating various aspects and embodiments of the present invention: 
           [0017]      FIG. 2  is a schematic cross-sectional diagram showing details of the slurry supply device of the semiconductor manufacturing apparatus of  FIG. 1 , according to some embodiments of the present invention; 
           [0018]      FIGS. 3 through 5  are schematic diagrams showing supply-line flow details for various valve settings, according to further aspects of the present invention; 
           [0019]      FIG. 6  is a schematic block diagram of a particle size analyzer used in a semiconductor manufacturing apparatus according to further aspects of the present invention; 
           [0020]      FIG. 7  is a graph demonstrating reproducibility of measurements of a semiconductor manufacturing apparatus according to principles of the present invention; and 
           [0021]      FIG. 8  is a schematic block diagram of a semiconductor manufacturing apparatus according to still other embodiments of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0022]    Preferred embodiments of the present invention will be described below in more detail with reference to the accompanying drawings. The present invention may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present invention to those skilled in the art. Like reference numerals refer to like elements throughout. 
         [0023]      FIG. 1  is a schematic of a semiconductor manufacturing apparatus according to embodiments of the present invention. 
         [0024]    Referring to  FIG. 1 , a semiconductor manufacturing apparatus  1000  is configured to apply the slurry onto a semiconductor wafer and to perform a chemical-mechanical polishing process (CMP). The apparatus  1000  of this embodiment may be provided with an in-line monitoring system  800  for measuring the quality of the slurry, which may be connected to four slurry supply devices  100 ,  200 ,  300 , and  400 . Each of the four slurry supply devices  100 - 400  is configured to supply the slurry to polishers  150 ,  250 ,  350 , and  450 , respectively. The in-line monitoring system  800  may receive the slurry from the four slurry supply devices  100 - 400  through sampling lines  116 ,  216 ,  316 , and  416 , and measure the particle size of the slurry for each of the slurry supply devices  100 - 400 . 
         [0025]    Regarding some of the embodiments of the present invention described herein, “measuring the particle size of the slurry” generally means measuring the number of slurry particles in size categories and evaluating the quality of the slurry. When the slurry particle size measurements show that there are coarse slurry particles present that may cause micro scratches to a wafer during CMP, the slurry quality may be determined to be defective, and when the measurements do not show such particles present, the slurry may be determined to be of good quality. The “particles” described herein refer to particles that have the potential to inflict micro scratches on a wafer. 
         [0026]    The apparatus  1000  provided with the in-line monitoring system  800  for measuring slurry quality for each of the slurry supply devices  100 - 400  will now be explained in detail. It should be noted that the description provided below of the slurry supply device  100  and the sampling line  116  may be representative of the other slurry supply devices  200 - 400  and sampling lines  216 - 416 . 
         [0027]    The slurry supply device  100  may supply the slurry used for CMP by transporting it in its undiluted state to a polisher that is the point of use (POU). The slurry may undergo various processes according to slurry type. The slurry supply device  100  may provide the slurry by storing it in its undiluted state in a drum and supplying it to the polisher  150  through a slurry supplying line  114 . The sampling line  116  that provides the slurry for sampling to the in-line monitoring system  800  may be connected to the slurry supplying line  114 . Before the slurry is provided to the polisher  150  in its undiluted state, the sampling line  116  is structured to bypass the slurry from the slurry supplying line  114 . 
         [0028]      FIG. 2  is a schematic cross-sectional diagram showing details of the slurry supply device  100  of the semiconductor manufacturing apparatus  1000  of  FIG. 1 , according to various embodiments of the present invention. 
         [0029]    Referring to  FIG. 2 , the slurry supply device  100  may include a drum  12  that stores undiluted slurry  11 , a mixing tank  15  for mixing the undiluted slurry  11  with deionized water, and a storage tank  17  that stores and provides a slurry mixture  11 A of the slurry and the deionized water to the polisher  150 . The undiluted slurry  11  may flow through a slurry supply line  20  by means of a pump  13 , and may be filtered by a filter  14  and transferred to the mixing tank  15 . The undiluted slurry  11  may be mixed with the deionized water in the mixing tank  15 . To attain a uniform slurry mixture  11 A, the slurry mixture  11 A may be circulated through a circulating line  23  by the operation of a pump  16 . The slurry mixture  11 A may be transferred to the storage tank  17  through a slurry supply line  21 , and circulated around a circulating line  24  to prevent its degeneration. Supply slurry  11 B stored in the storage tank  17  may be supplied by flowing through a supply line  22  and filtered by a filter  19 . 
         [0030]    In the above-described slurry supply apparatus  100 , the sampling line  116  ( FIG. 1 ) may be installed in such a way that the slurry is not subject to effects from stress, flow quantity, pressure, etc. For example, the sampling line  116  may be formed on the slurry supply line  20  that transfers the undiluted slurry  11  from the slurry drum  12  to the mixing tank  15 . Also, the sampling line  116  may be located after the filtering by the filter  19  and before the supplying to the polisher, as shown in  FIG. 2 . 
         [0031]    Referring again to  FIG. 1 , the sampling line  116  may be formed to allow its inside to be cleaned. For instance, two 3-way valves  118  and  120  may be installed on the sampling line  116 . The 3-way valve  118  may have an inflow line  122  connected thereto for providing deionized water to the sampling line  116 , and the other 3-way valve  120  may have an outflow line  124  for discharging the deionized water from the sampling line  116 . The deionized water may be used as a cleaning solution for cleaning the inside of the sampling line  116 . The slurry that passes through the sampling line  116  may be supplied to the in-line monitoring system  800  for performing quality inspection of a sample thereof, and the deionized water that cleans the inside of the sampling line  116  may be provided to the in-line monitoring system  800  to measure the cleanliness of the inside of the sampling line  116 . 
         [0032]      FIGS. 3 through 5  are schematics showing supply-line flow details for various valve settings, according to embodiments of the present invention. 
         [0033]    Referring to  FIG. 3 , the 3-way valves  118  and  120  may be controlled to prevent the slurry from being supplied into the sampling line  116  while deionized water is being supplied through the inflow line  122  into the sampling line  116  and then discharged through the outflow line  124 . In this fashion, the deionized water can clean the sampling line  116  to prevent impurities from entering the slurry when it flows through the sampling line  116 . The sampling line  116  may be cleaned before and after a quality measurement of the slurry. 
         [0034]    Referring to  FIG. 4 , the 3-way valves  118  and  120  may be controlled to prevent the deionized water from being supplied into the sampling line  116  while enabling the slurry to flow through the sampling line  116 . Thus, the slurry may be supplied to the in-line monitoring system  800  to determine whether its quality is good or defective. 
         [0035]    Referring to  FIG. 5 , to measure the degree of cleanliness of the sampling line  116  (which may, for example, be represented by the number of particles inside the sampling line  116 ), the 3-way valves  118  and  120  are controlled to prevent the slurry from being supplied into the sampling line  116  while supplying the deionized water through the inflow line  122  into the sampling line  116 . Here, the outflow line  124  is closed and the deionized water is supplied into the in-line monitoring system  800 . Monitoring the degree that the slurry is agglomerated within the sampling line  116  may be used to determine when the slurry supplying apparatus  100  including the sampling line  116  should be cleaned. 
         [0036]    Referring again to  FIG. 1 , the in-line monitoring system  800  may be configured to measure the number of particles from the slurry sample. The in-line monitoring system  800  may include a multi-line junction  500 , a particle size analyzer  600 , and a controller  700 . The slurry flowing through the sampling line  116  may be supplied through the multi-line junction  500  to the in-line monitoring system  800 . The multi-line junction  500  receives lines  512 ,  514 ,  516 , and  518 , which are respectively connected to the four sampling lines  116 ,  216 ,  316 , and  416  to receive the slurry. The slurry that passes through the multi-line junction  500  may be supplied to the particle size analyzer  600  to measure its quality. The particle size analyzer  600  may first dilute the slurry to measure the size and number of particles mixed in the slurry. 
         [0037]      FIG. 6  is a structural diagram of a particle size analyzer in a semiconductor manufacturing apparatus according to embodiments of the present invention. 
         [0038]    Referring to  FIG. 6 , the slurry that is supplied through a line  520  from the multi-line junction  500  may be mixed with a diluent that passes through a diluent inflow line  604  in a sample loop  620 , to be diluted and then supplied to a first diluting device  630  through a line  622 . The diluent may be deionized water, which may be supplied to the sample loop  620  at a uniform flow rate through a line  612  by means of a uniform pressure generated by a diluent pump  610 . Accordingly, the slurry mixed with the deionized water in the sample loop  620  may also receive a uniform pressure, from a diluent pump  610 , to flow at a constant flow rate to be diluted and subsequently supplied to the first diluting device  630 . Diluting the slurry with the deionized water makes it easier to measure the size and number of particles mixed in the slurry. 
         [0039]    The slurry that is diluted in the first diluting device  630  may be discharged through a line  632  and may be supplied to a second diluting device  640  to be diluted further. This additional diluting may be performed by supplying deionized water through a line  634  to the second diluting device  640 . The slurry that is re-diluted by the second diluting device  640  may be discharged through a line  642  and then supplied to a sensor  650 . The sensor  650  may be configured to measure the number of particles mixed in the diluted slurry, for example, particles that are approximately 1 μm or larger, which are liable to cause micro-scratches on a wafer that is to be polished. The sensor  650  may, for example, use light extinction/scattering to sense particles&#39; presence and size. The sensor  650  may output a result to the controller  700  ( FIG. 1 ). Such sensors are well-known in the art and may include, for instance, a single particle optical sensing sensor. 
         [0040]    The diluted slurry that has been sampled may be drained through a line  652 . Lines  602  and  624  may be used to flush the slurry from the particle size analyzer  600 . The lines  602  and  624  may drain the slurry if an error occurs in an initial setting of the particle size analyzer  600 . 
         [0041]    The controller  700  may be configured to control the particle size analyzer  600  according to a set of parameters, such as the amount of desired diluting, the sampling duration, data collecting duration, the flow speed of the diluent, the volume of the sample loop, the flush duration, and the like. The controller  700  may control the operation of the slurry supply devices  100 - 400  and the polishers  150 - 450  based on the data monitored by the particle size analyzer  600 . In this fashion, the controller  700  may prevent defective slurry from being supplied to the polishers  150 - 450  so that the occurrence of micro scratches during CMP is prevented. 
         [0042]      FIG. 7  is a graph demonstrating reproducibility of measurements in a semiconductor manufacturing apparatus according to embodiments of the present invention. 
         [0043]    Referring to  FIG. 7 , the graph displays the results of measurements performed by the in-line monitoring system  800  as circular dots, and displays the results measured by an off-line particle size analyzer as square points. When the in-line measurement results and the off-line measurement results are compared, it can be seen that they are almost identical. That is, the results measured by the in-line monitoring system  800  are accurate. 
         [0044]      FIG. 8  is a structural schematic block diagram of a semiconductor manufacturing apparatus according to embodiments of the present invention. 
         [0045]    Referring to  FIG. 8 , the slurry supply devices  100 - 400 , the polishers  150 - 450 , and the in-line monitoring system  800  may be connected to communicate with one another and share data through wires or wirelessly. When the particle size of the slurry appears to exceed a predetermined particle size, the controller  700  may perform a controlling function that prevents further slurry from being introduced to the polishers  150 - 450 . This poor slurry stored in the slurry supply devices  100 - 400  may then be drained in its entirety, and new slurry may then be supplied. 
         [0046]    The above-structured semiconductor manufacturing apparatus may be used to perform a slurry quality assessment as described below. 
         [0047]    Referring to  FIG. 1 , the sampling line  116  that branches from the slurry supplying line  114  may be cleaned with deionized water before and after slurry quality measurements are performed. The cleaning of the sampling line  116  may be performed while not supplying the slurry into the sampling line  116 , and instead supplying the deionized water to the sampling line  116  through the line  122 , and then draining the deionized water through the line  124 , by controlling the 3-way valves  118  and  120 , as depicted in  FIG. 3 . 
         [0048]    To measure the quality of the slurry, as shown in  FIG. 4 , deionized water may be prevented from being supplied into the sampling line  116 , and instead the slurry may be supplied into the sampling line  116  and then transferred to the multi-line junction  500 , by controlling the opening and closing of the 3-way valves  118  and  120 . In this case, the slurry may pass through the multi-line junction  500  and be supplied to the particle size analyzer  600 . The slurry supplied to the particle size analyzer  600 , as shown in  FIG. 6 , may be diluted by the deionized water in the first and second diluting devices  630  and  640 . Meanwhile, the diluted slurry may be supplied to the sensor  650  to measure the number and size of the slurry particles. The diluent pump  610  may be provided with the particle size analyzer  600  to generate a predetermined pressure and flow rate of the slurry and deionized water that flows through the particle size analyzer  600 . 
         [0049]    When the number or size of particles within the slurry is detected to exceed a set value, the slurry waiting to be used in the slurry supply device  100  may be drained and replaced with fresh slurry. Slurry quality may be measured in real time, and each of the slurry supply devices  100 - 400  may be separately controlled. Also, data for the slurry supplied from the in-line monitoring system  800  may be used to analyze details of the reasons for micro scratch occurrence during CMP processes. 
         [0050]    As shown in  FIG. 5 , to monitor the degree of cleanliness of the sampling pipe  116 , the 3-way valves  118  and  120  may be controlled to withhold the supply slurry from the sampling line  116 , and instead supply deionized water into the sampling line  116  through the line  122  to the multi-line junction  500 . The particles within the sampling line  116  may be supplied to the particle size analyzer  600  by passing through the multi-line junction  500 . By measuring the number of particles mixed with the deionized water in the particle size analyzer  600 , the degree of cleanliness of the sampling line  116  can be measured. When the degree of cleanliness of the sampling line  116  satisfies a desired level, the quality of the slurry may then be measured. As described above, the number and size of particles within the sampling line  116  may be checked and, based on the results, the time for cleaning the slurry supply device  100  can be determined. 
         [0051]    As described above in this detailed description, the occurrence of micro scratches during CMP can be anticipated and prevented by supplying slurry after a distribution analysis of particles in the slurry is performed. Therefore, the quality of the slurry can be maintained, and yield from a CMP process can be increased. 
         [0052]    The above-disclosed subject matter is to be considered illustrative, and not restrictive, of the present invention, and the appended claims are intended to cover all modifications, enhancements, and other embodiments, that fall within the true spirit and scope of the present invention. The scope of the present invention should therefore be determined by giving the claims their broadest permissible interpretation including their equivalents, and should not be restricted or limited by the foregoing detailed description.