Abstract:
A polishing apparatus that polishes a substrate to be processed includes a rotary polishing table carrying a polishing pad on a surface thereof, and a polishing head that urges the substrate to be processed against the polishing pad while rotating the substrate to be processed, wherein the polishing head holds the substrate to be processed by a retainer ring, the retainer ring includes: a resin ring formed of a resin and contacted with the polishing pad; and an upper part ring that holds the resin ring, at least first and second patterns of convex shape or concave shape are formed on a junction surface of the upper part ring where the upper part ring is contacted with the resin ring, at least third and fourth patterns of concave shape or convex shape are formed on a junction surface of the resin ring where the resin ring makes contact with the upper electrode, in a manner complementary to the patterns of the convex shape or concave shape formed on the junction surface of the upper electrode.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    The present application is based on Japanese priority application No.2006-244305 filed on Sep. 8, 2006, the entire contents of which are hereby incorporated by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    The present invention generally relates to manufacturing of electronic apparatuses and more particularly to a chemical mechanical polishing apparatus used for manufacturing of such an electronic apparatus. 
         [0003]    The technology of chemical mechanical polishing (CMP) has been used extensively for forming Cu multilayer interconnection structure by a damascene process or dual damascene process. On the other hand, because of the capability of providing near ideal flat surface in the processed surface, chemical mechanical polishing process provides a particularly advantageous effect when used with a photolithographic process that includes a high resolution exposure process and hence characterized by shallow focal depth. Thus, chemical mechanical polishing process is used extensively in these days as the technology indispensable for the production of semiconductor integrated circuit devices of high integration density or for the production of high resolution display devices. 
       Patent Reference 1 
       [0004]    Japanese Laid-Open Patent Application 2005-34959 Official Gazette 
       Patent Reference 2 
       [0005]    Japanese Laid-Open Patent Application 2000-301452 Official Gazette 
       SUMMARY OF THE INVENTION 
       [0006]      FIG. 1  shows the construction of a polishing apparatus  100  according to a related art of the present invention. 
         [0007]    Referring to  FIG. 1 , the polishing apparatus  100  has a construction of using a polishing pad  101  fixed upon a rotating polishing table  102 , and a substrate  103  such as a wafer to be processed is urged against the polishing pad  101  covering the surface of the rotating polishing table  102  by using a polishing head  104  that urges the substrate  103  against the polishing pad  101  with a predetermined pressure while rotating the substrate  103 . 
         [0008]    Further, with the polishing apparatus  100  of  FIG. 1 , slurry  106  is supplied upon the polishing pad  101  from a supply nozzle  105  in the form of liquid, wherein the slurry causes a chemical reaction with the surface of the substrate to be processed at the part where the polishing pad  101  makes a contact with the substrate  103 . Thereby, the reaction product formed as a result of the reaction is removed by the mechanical action of the abrasive particles contained in the slurry or by the mechanical action of the polishing pad. There can also be a case with such a chemical mechanical polishing process in which the slurry does not containing abrasive particles. 
         [0009]    Further, in order to maintain the fresh surface state of the polishing pad  101 , there is provided a roughening device  107  on the polishing table  102  at a location different from the location where the polishing head  104  is provided. 
         [0010]      FIG. 2  shows the details of the polishing head  104 . 
         [0011]    Referring to  FIG. 2 , the polishing head  104  includes a membrane  121  that urges the substrate  103  to be processed against the polishing pad  101  with pressure, wherein the membrane  121  and the substrate  103  are held by a retainer ring  122 . The retainer ring  122  not only holds the membrane  121  and the substrate  103  but also functions to improve the in-plane distribution of polishing as it is urged against the polishing pad  101 . 
         [0012]      FIG. 3  shows the details of the retainer ring  122  of the  FIG. 2 . 
         [0013]    Referring to  FIG. 3 , the retainer ring  122  is formed of an upper part ring  122   a  of a metal member such as stainless steel and a resin ring  122   b  formed under the upper part ring  122   a  and is urged against the polishing pad  101 . It should be noted that the resin ring  122   b  is adhered to the upper part ring  122   a  by an adhesives at a junction surface  122   c.    
         [0014]    Meanwhile, with recent chemical mechanical polishing apparatuses, there is an increasing opportunity of polishing a wafer of 30 cm diameter in the prospect of improved productivity of electronic apparatuses. However, in the case of polishing a wafer of such a large diameter, it was discovered that there occurs, in some cases, a rupture at the junction surface  122   c.    
         [0015]    Further, in the case of the retainer ring of the type in which the resin ring  122   b  and the upper part ring  122   a  are fixed with each other by way of screws, too, it was discovered that such a rupture occurs at the junction surface in the vicinity of the screwed parts. 
         [0016]    When there occurs a rupture at such a junction surface between the resin ring  122   b  and the upper part ring  122   a,  not only the polishing apparatus is damaged, but there is also caused a deterioration of yield in the polishing process by the fragments falling upon the polishing pad  101 . 
         [0017]    It is believed that such a rupture between the resin ring  122   b  and the upper part ring  122   a  is caused as a result of increase of the stress applied to the resin ring  122   b  as a result of increase of friction between the polishing pad and the retainer ring particularly at the peripheral part of the retainer ring, while such increase of friction becomes conspicuous when the diameter of the substrate  103  to be processed is increased. 
         [0018]    Thereupon, it may be conceivable that such a rupture between the resin ring  122   b  and the upper part ring  122   a  may be avoided by forming the whole retainer ring  122  by a resin. However, even in such a case of the retainer ring of unitary resin construction, there is a need of connecting the resin ring to a metal member constituting a part of the polishing head  104  at some location, and thus, this problem of rupture at the connection part cannot be avoided in any of the case of achieving the connection by an adhesive and the case of achieving the connection by screws. 
         [0019]    The present invention proposes a polishing apparatus that polishes a substrate to be processed, comprising: 
         [0020]    a rotary polishing table carrying a polishing pad on a surface thereof; and 
         [0021]    a polishing head that urges said substrate to be processed against said polishing pad while rotating said substrate to be processed, 
         [0022]    wherein said polishing head holds said substrate to be processed by a retainer ring, 
         [0023]    said retainer ring comprising: a resin ring formed of a resin and contacted with said polishing pad; and 
         [0000]    an upper part ring that holds said resin ring, 
         [0024]    at least first and second patterns of convex shape or concave shape being formed on a junction surface of said upper part ring where said upper part ring is contacted with said resin ring, 
         [0025]    at least third and fourth patterns of concave shape or convex shape being formed on a junction surface of said resin ring where said resin ring makes contact with said upper electrode, in a manner complementary to the said patterns of said convex shape or concave shape formed on said junction surface of said upper electrode. 
         [0026]    Further, the present invention provides a manufacturing method of an electronic apparatus using such a polishing apparatus. 
         [0027]    Thus, by forming at least the first and second patterns of convex or concave shape on the junction surface of the upper ring and further by forming at least the third and fourth patterns of convex or concave shape on the junction surface of the resin ring in complementary manner to the first and second patterns at the time of joining the upper ring and the resin ring constituting the retainer ring, it becomes possible to avoid damaging of the junction part between the resin ring and the upper ring, even when a large stress is applied to the resin ring, and it becomes possible to conduct the desired polishing process efficiently and with high yield. 
         [0028]    Other objects and further features of the present invention will become apparent from the following detailed description when read in conjunction with the attached drawings. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0029]      FIG. 1  is a diagram showing the construction of a polishing apparatus according to a related art of the present invention; 
           [0030]      FIG. 2  is a diagram showing the construction of a polishing head used with the polishing apparatus of  FIG. 1 ; 
           [0031]      FIG. 3  is a diagram showing the construction of a retainer ring used with the polishing head of  FIG. 2 ; 
           [0032]      FIG. 4  is a diagram showing the construction of a polishing apparatus according to a first embodiment of the present invention; 
           [0033]      FIG. 5  is a diagram showing construction of a polishing head used with the polishing apparatus of  FIG. 4 ; 
           [0034]      FIG. 6  is a diagram showing the construction of a retainer ring used the polishing head of  FIG. 5 ; 
           [0035]      FIGS. 7A and 7B  are diagrams showing the construction of an upper part ring of the retainer ring of  FIG. 6  respectively in a plan view and cross-sectional view; 
           [0036]      FIGS. 8A and 8B  are diagrams showing the construction of a resin ring of the retainer ring of  FIG. 6  respectively in a plan view and a cross-sectional view; 
           [0037]      FIGS. 9A and 9B  are diagrams showing a connection of the upper part ring and the resin ring of  FIGS. 7 and 8 ; 
           [0038]      FIGS. 10A and 10B  are diagrams showing a modification of the retainer ring of  FIG. 6 ; 
           [0039]      FIGS. 11A and 11B  are diagrams showing a different modification of the retainer ring of  FIG. 6 ; 
           [0040]      FIGS. 12A and 12B  are diagrams showing a connection of the upper part ring and the resin ring of  FIGS. 11A and 11B ; and 
           [0041]      FIGS. 13A-13D  are diagrams showing the fabrication process of a semiconductor device according to a second embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     First Embodiment 
       [0042]      FIG. 4  shows the construction of a polishing apparatus  10  according to a first embodiment of the present invention. 
         [0043]    Referring to  FIG. 1 , the polishing apparatus  10  has a construction in which a polishing pad  11  is fixed upon a rotating polishing table  12 , and a substrate  13  such as a wafer to be processed is urged against the surface of the polishing table  12  by a rotating polishing head  14  with a predetermined pressure. 
         [0044]    Further, with the polishing apparatus  10  of  FIG. 4 , slurry  16  is supplied upon the polishing pad  11  from a supply nozzle  15  in the form of liquid, wherein the slurry causes a chemical reaction with the surface of the substrate to be processed at the part where the polishing pad  11  makes a contact with the substrate  13  to be processed. Thereby, the reaction product formed as a result of the reaction is removed by the mechanical action of the abrasive particles in the slurry or by the mechanical action of the polishing pad  11 . There can also be a case with such a chemical mechanical polishing process in which slurry not containing abrasive particles is used. 
         [0045]    Further, in order to maintain the fresh surface state of the polishing pad  11 , there is provided a roughening device  17  on the polishing table  12  at a location different from the location where the polishing head  14  is provided. 
         [0046]    Thus, with the polishing apparatus of  FIG. 4 , the polishing head  14  is urged against the polishing pad  11  with a predetermined pressure, and chemical mechanical polishing is applied to the surface of the substrate  13  to be processed by dripping the slurry  16  while rotating the polishing head  14  and the polishing table  12  with respective rotational speeds. 
         [0047]    With the polishing apparatus  10  of  FIG. 4 , not only the silicon wafer of conventional diameter of 20 cm but also the silicon wafer of larger diameter of 30 cm or more can be polished as the substrate  13 , and thus, the polishing head  14  can hold thereon such a large diameter semiconductor wafer. 
         [0048]    It should be noted that the above polishing condition, the slurry and the polishing pad  11  can be changed as necessary according to the nature of the film to be polished on the substrate  13 . 
         [0049]      FIG. 5  shows the details of the polishing head  14 . 
         [0050]    Referring to  FIG. 5 , the polishing head  14  includes a membrane  21  that urges the substrate  13  to be processed against the polishing pad  11 , wherein the membrane  21  and the substrate  13  are held by the retainer ring  22 . It should be noted that the retainer ring  22  not only holds the membrane  21  and the substrate  13  to be processed thereon but it is possible to improve the in-plane distribution of the polishing by being urged against the polishing pad  11 . 
         [0051]      FIG. 6  shows the details of the retainer ring  22  of the  FIG. 2 . 
         [0052]    Referring to  FIG. 6 , the retainer ring  22  is formed of an upper part ring  22   a  of a metal member such as stainless steel and a resin ring  22   b  of a resin such as polyether ether ketone (PEEK) formed under the upper ring  22   a  such that the resin ring  22   b  is urged against the polishing pad  11 , wherein the resin ring  22   b  is adhered to the upper part ring  22   a  by an adhesive at a junction surface  22   c.    
         [0053]      FIG. 7A  shows the upper part ring  22   a  as viewed from a lower part in a plan view, while  FIG. 7B  shows the upper part ring  22   a  in a cross-sectional view taken along a line A-A in  FIG. 7A . 
         [0054]    Referring to  FIGS. 7A and 7B , the bottom surface  22   c   1  of the upper part ring  22   a  forms one part of the junction surface  22   c  of  FIG. 6 , wherein the bottom surface  22   c   1  is formed with a first pattern  23   a   1  of a groove that goes around the upper part ring  22   a  and a second pattern  23   a   2  of plural grooves  23   a   2  each formed in a radial direction. 
         [0055]      FIG. 8A  shows the resin ring  22   b  in a plan view as viewed from an upward direction, while  FIG. 8B  shows the resin ring  22   b  in a cross-sectional view taken along a line B-B′ of  FIG. 8A . 
         [0056]    Referring to  FIGS. 8A and 8B , the upper surface  22   c   2  of the resin ring  22   b  forms the other part of the junction surface  22   c  of  FIG. 6 , wherein it can be seen that there are formed a first pattern  23   b   1  of a convex part that goes around the resin ring  22   b  and a second pattern  23   b   2  of plural convex parts each formed in a radial direction. 
         [0057]    The convex part  23   b   1  is formed with a complementary shape corresponding to the groove  23   a   1 , while the convex parts  23   b   2  are formed with a correspondingly complementary shape of the grooves  23   a   2 . Thus, in the case the upper part ring  22   a  and the resin ring  22   b  are coupled with each other as shown in  FIG. 6 , the convex part  23   b   1  engages with to the groove  23   a   1  as shown in the cross-sectional view of  FIG. 9A . Similarly, the convex parts  23   b   2  engage with respective, corresponding grooves  23   a   2  although not illustrated. 
         [0058]    Thus, by fixing the upper part ring  22   a  and the resin ring  22   b  with each other in such a mutually engaged state by an adhesive in the retainer ring  22  of  FIG. 6 , the stress acting upon the resin ring  22   b  is distributed to the convex parts  23   b   1  and  23   b   2  and to the grooves  23   a   1  and  23   a   2 , and the problem of the upper part ring  22   a  and resin ring  22   b  causing rupture at the junction surface  22   c  is avoided. 
         [0059]    Further, as shown in  FIG. 9B , the stress acting upon the resin ring  22   b  is distributed to the convex parts  23   b   1  and  23   b   2  and further to the grooves  23   a   1  and  23   a   2  even in the case the coupling between the upper part ring  22   a  and the resin ring  22   b  is achieved by using screws  22   d,  and the problem of the upper part ring  22   a  and the resin ring  22   b  causing rupture at the junction surface  22   c  is avoided. 
         [0060]    Furthermore, it is evident with the present embodiment that similar effects are attained in the case the grooves and the convex parts are formed oppositely to the upper ring  22   a  and the resin ring  22   b,  and thus, for the case when the grooves  23   a   1  and  23   a   2  are formed on the resin ring  22   b  and the convex parts  22   b  al and  22   b    2  are formed on the upper part ring  22   a.    
         [0061]      FIGS. 10A and 10B  show a modification of the first embodiment. 
         [0062]    Referring to  FIGS. 10A and 10B , the present embodiment eliminates the groove  23   a   1  extending in the circumferential direction from the junction surface  22   c   1  and the convex part  23   b   1  extending in the circumference direction from the junction surface  22   c   2 , and thus, there are formed only the grooves  23   a   2  and the projections  23   b   2  extending in the radial direction. 
         [0063]    Because the stress acting upon the junction surface  22   c  by the friction acting to the polishing pad  11  works primarily in the circumferential direction, it is possible to suppress the rupture at the junction surface  22   c  effectively even in such a case in which only the grooves  23   a   2  and the convex part  23   b   2  are formed to extend in the radial direction respectively on the upper part ring  22   a  and the resin ring  22   b.    
         [0064]      FIGS. 11A and 11B  show another modification of the present embodiment. 
         [0065]    Referring to  FIGS. 11A and 11B , there are formed plural, mutually independent depressions  23   a  on the junction surface  22   c   1  of the upper part ring  22   a,  and there are formed plural, mutually independent convex part  23   bs  at the junction surface  22   c   2  of the resin ring  22   b  in a complementary manner to the depressions  23   a.    
         [0066]    Thus, in the case of forming the retainer ring  22  by coupling the upper part ring  22   a  and the resin ring  22   b  as shown in  FIG. 12A , the convex parts  23   b  are accepted by the corresponding depressions  23   a  and the resin ring  22   b  is fixed firmly against the upper part ring  22   a  in this state. Because the respective grooves  23   a  and the respective convex parts  23   b  form an isolated pattern in the present embodiment, the position of the resin ring  22   b  is determined against the upper part ring  22   a  in both the circumferential direction and the radial direction, and occurrence of rupture is suppressed at the junction surface  22   c  even in the case a stress is applied in any of the circumferential direction and the radial direction. 
         [0067]    In the present modification, too, the upper part ring  22   a  and the resin ring  22   b  may be fixed with each other by adhesives in the state of  FIG. 12A , while these can be fixed also by using screws  23   d  as shown in  FIG. 12B . 
         [0068]    Further, with the present modification, it is also possible to form the grooves  23   a  on the resin ring  22   b  and form the convex parts  23   b  in the upper part ring  22   a  also in the present modification. 
       Second Embodiment 
       [0069]      FIGS. 13A-13D  show a fabrication process of a semiconductor device according to a second embodiment of the present invention that uses the polishing apparatus  10  of  FIG. 4 . 
         [0070]    Referring to  FIG. 13A , a silicon substrate  41  of a silicon wafer of 30 cm diameter is formed with an SiN pattern  43  via a sacrificial oxide film  42  of a thermal oxide film, wherein there is formed a device isolation trench  41 A in the silicon substrate  41  so as to define a predetermined device region  41 B by a dry etching process while using the SiN pattern  43  as a mask. 
         [0071]    Next in step of  FIG. 13B , there is formed an SiO 2  film  44  on the structure of the  FIG. 13A  by a CVD process so as to fill the device isolation trench  41 A, and the silicon substrate  41 , now in the state in which the structure of the  FIG. 13B  is formed, is held on the polishing head  14  of the polishing apparatus  10  as explained with reference to  FIGS. 4-6  in the step of  FIG. 13C  as the substrate  13  to be processed, wherein the retainer ring  22  and the membrane  21  explained with reference to  FIGS. 7-8  are used for holding the silicon substrate  41  on the polishing head  14 . 
         [0072]    Further, in the step of  FIG. 14C , a commercially available polishing pad marketed for example by Rodel Nitta Company under the trade name IC1010 is used for the polishing pad  11 , and polishing of the SiO 2  film  44  is conducted by using a commercially available slurry marketed from Cabot Company under the trade name SS25, for the slurry with 1:1 dilution. Thereby, the polishing is conducted by rotating the polishing table  12  with a rotational speed of 110 rpm and rotating the polishing head  14  with a rotational speed of 98 rpm. During this polishing process, the polishing head  14  is urged against the polishing pad  11  by using the membrane  21  with a pressure of 280 gweight/cm 2 . Thereby, polishing of the SiO 2  film  44  is conducted until the SiN pattern  43  is exposed. In this case, the retainer ring  22  is urged against the polishing pad  11  with a pressure of about 700 g/cm 2 . 
         [0073]    In the step of  FIG. 13C , the SiN film  43  functions as a polishing stopper, and a device isolation insulation film  44 A of SiO 2  is formed in correspondence to the device isolation trench  41 A so as to define the device region  41 B on the surface of the substrate  41 . 
         [0074]    Next, in the step of  FIG. 14C , the SiN film  43  and also the sacrifice oxide film  42  are removed, and formation of the desired semiconductor device is conducted on the device region  41 B thus exposed. 
         [0075]    With the present embodiment, damaging of the retainer ring  22  is suppressed as a result of the use of the polishing apparatus  10 , which in turn uses the retainer ring  22  explained previously, for the chemical mechanical polishing process of  FIG. 13C , even in the case that the substrate  13  to be processed is a semiconductor wafer of large diameter, and it becomes possible to improve the efficiency and yield at the time of production of the semiconductor device. 
         [0076]    While the present invention has been explained for preferred embodiments, the present invention is by no means limited to the embodiments described heretofore, but various variations and modifications may be made without departing from the scope of the invention.