Patent Publication Number: US-6663474-B2

Title: Apparatus and system of chemical mechanical polishing

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to chemical mechanical polishing equipment, and more particularly to apparatus of carrier in the chemical mechanical polishing equipment. 
     2. Description of the Prior Art 
     Fabrication of semiconductor integrated circuits (IC) is a complicated multi-step process creating microscope structures with various electrical properties to form a connected set of devices. As more layers are built up on the silicon wafer, problems caused by surface non-planarity become increasingly severe and can impact yield and chip performance. During the fabrication process, it may become necessary to remove excess material in a process referred to as planarization. 
     A common technique used to planarize the surface of a silicon wafer is CMP. CMP involves the use of a polishing pad affixed to a circular polishing table and a holder to hold the wafer face down against the rotating pad. A slurry containing abrasive and chemical additives are dispensed onto the polishing pad. 
     As depicted in FIG. 1, a CMP system  110  typically consists of a carrier module  120 , a support module  130 , a polishing pad module  140 , and a conditioning module  150 . Typically a polishing pad on the circular polishing table in the polishing pad module  140  is comprised of blown polyurethane with a felt surface layer containing many small pores to facilitate the flow of slurry to beneath the wafer being polished. The carrier module  120  provides the holder to hold the wafer face down against the rotating pad. Typically a retaining ring  125  in the carrier module  120  can prevent the wafer edge against contact with the polishing pad in a deformed shape. 
     On the other hand, the support module  130  comprises a rotation system  132 , a pressure system  134  and a chemical system  136 . The rotation system  132  is used for the rotation motion of the carrier module  120 . The pressure system  134  is used for providing the down force of the carrier module  120  to keep the wafer in contact with the polishing pad. The chemical system  136  is responsible for supply of the slurry containing abrasive and chemical additives. Furthermore, the conditioning module  150  comprises a conditioning chemical system  154  and a robot system  155 . The conditioning chemical system is responsible for the supply of the conditioning solution. The robot system  155  is used to the mechanical motion during conditioning process. 
     It is very important for the CMP system  110  to provide the smooth-changed and controllable polishing rate. However, the typical CMP system  110  only maintains the polishing rate in either ex-situ or non-real-time-in-situ pad conditioning, that is, the pad conditioning step can&#39;t be simultaneously implemented with the polishing step. Such an architecture may not fulfill the further shrunk IC design and manufacture. On the other hand, there is occupied space for the conditioning module, that causes the higher consumption of the CMP system in a semiconductor manufacture factory. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide apparatus of carrier and a system of chemical mechanical polishing. A retaining ring combined with the conditioning function can provide activating pad and polishing wafer real-in-situ. 
     It is another object of the present invention to provide apparatus of carrier and a system of chemical mechanical polishing. A retaining ring made of the material of the conventional conditioner can be controlled with independent rotation motion and down-force supply. 
     In the present invention, apparatus of carrier in chemical mechanical polishing equipment comprises a carrier module for holding a wafer face down. A retaining ring and conditioning module is coupled to the carrier module, which is used for protecting the wafer edge against contact with a polishing pad in a deformed shape and executing a conditioning of the polishing pad while the wafer is being polished. A first support module is coupled to the retaining ring and conditioning module, which is used for rotating, pressing down, and supplying conditioning chemicals for the retaining ring and conditioning module. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A better understanding of the invention may be derived by reading the following detailed description with reference to the accompanying drawing wherein: 
     FIG. 1 is a schematic diagram illustrating the architecture of a typical chemical-mechanical polishing system nowadays; 
     FIG. 2 is a schematic diagram illustrating the architecture of the chemical-mechanical polishing equipment in accordance with the present invention; and 
     FIG. 3 is a cross sectional diagram illustrating a part of elements of the chemical-mechanical polishing equipment in accordance with the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     While the invention is described in terms of a single preferred embodiment, those skilled in the art will recognize that many modules described below can be altered and that species and types as well as other substitutions can be freely made without departing from the spirit and scope of the invention. 
     Furthermore, there is shown a representative portion of a system of the present invention in enlarged, the drawings are not necessarily to scale, as the modules are shown for clarify of illustration and should not be interpreted in a limiting sense. 
     In the present invention, a system of chemical mechanical polishing comprises a carrier module comprising a holder for holding a wafer face down. A polishing pad module comprising a polishing pad is used for providing a motion and a mount of the polishing pad. A retaining ring and conditioning module is coupled to the carrier module, which is used for protecting the wafer against contact with the polishing pad and executing a conditioning of the polishing pad. A first support module is coupled to the retaining ring and conditioning module, which is used for rotating, pressing down, and supplying conditioning chemicals for the retaining ring and conditioning module. A second support module is coupled to the carrier module, which is used for rotating, pressing down, and supplying polishing chemicals for the holder. 
     FIG.2 shows a schematic diagram illustrating the architecture of a CMP system in accordance with the present invention. A CMP system  10  consists of a carrier support module  30 , a carrier module  20 , a retaining ring and conditioning module  25 , a conditioning support module  50 , and a polishing pad module  40 . The carrier module  20  consists of a related circuit and a holder for holding a wafer face down. The carrier support module  30  coupled to the carrier module  20  consists of a rotation system  32 , a pressure supply system  34 , and a chemical supply system  36 . The rotation system  32  is responsible for the rotation motions of the holder in the carrier module  20  during a polishing process. The pressure supply system  34  provides down force for the wafer against a polishing pad. The chemical supply system  36  is responsible to provide polish-related chemical additives, such as slurry containing abrasive. The polishing pad module  40  consists of a polishing pad affixed to a linear or a rotational table. 
     A key of the present invention is the retaining ring and conditioning module  25 . The retaining ring and conditioning module  25  plays roles on not only retaining but also conditioning. The retaining ring and conditioning module  25  consists of a retaining ring coupled to the carrier module  20 . The retaining ring is made of the materials of the conventional conditioner, such as diamond planar grit, instead of ones of the conventional retaining ring, thus the retaining ring is referred as a conditioner. In order to offering suitable elasticity during the manufacture process, the material of the retaining ring is not restricted to the conventional materials of the conditioner. The advantage of the retaining ring combined with the function of the conditioner may occupy less space for the CMP system  10 . It is because the robot system of the conventional conditioner can be abandoned. 
     On the other hand, the conditioning support module  50  is coupled to the retaining ring and conditioning module  25 . A ring rotation system  54  and a ring pressure supply system  56  in the conditioning support module  50  are responsible for the rotation motions and down force supply of the retaining ring. The ring pressure supply system  56  can provide air or oil pressure to down the retaining ring. Thus, the rotation motions and the down force of the retaining ring are independent to the ones of the holder in the carrier module  20 . Furthermore, a conditioning chemical system  56  is used to supply necessary chemicals during the conditioning procedure. The combination of the retaining ring and conditioning module  20  and the conditioning support module  50  are able to activate the polishing pad just adjacent to polishing the wafer (real-in-situ) and keep company with the wafer (real time). Furthermore, the constant polishing rate can be ensured by always keeping the polishing pad condition as at-beginning. One purpose of the present invention is to provide the retaining ring with additive function of the conditioner. The retaining ring, made of the materials of the conditioner, may execute the conditioning procedure. On the other hand, an independent support system different from one for the holder may provider the conditioning procedure to execute flexibly and well. 
     FIG. 3 illustrates a cross sectional diagram of the chemical-mechanical polishing equipment in accordance with the present invention. A carrier module  78  consists of a holder  75  to hold a wafer  74 . A retaining ring  72  is connected to a conditioning support module  76  for rotation motion, pressure supply, and conditioning chemicals supply of the retaining ring  72  of the present invention. The retaining ring  76  can keep contact with a polishing pad  70  and execute conditioning for the polishing pad  70 . On the other hand, the carrier module  78  is connected to a carrier support module  80  for rotation motion, pressure supply, and polishing chemicals supply of the carrier module  78 . 
     While this invention has been described with reference to illustrative embodiments, this description is not intended to be construed in a limiting sense. Various modifications and combinations of the illustrative embodiments, as well as other embodiments of the invention, will be apparent to persons skilled in the art upon reference to the description. It is therefore intended that the appended claims encompass any such modifications or embodiments.