Abstract:
The present invention relates to a chemical mechanical polishing conditioner, comprising: a substrate; a binding layer disposed on the substrate; and multiple abrasive units placed on the binding layer; wherein each abrasive unit has an abrasive unit substrate and an abrasive layer which is a diamond film formed by chemical vapor deposition and has multiple abrasive tips; wherein the abrasive units have uniform heights, such that the abrasive units form a planarized surface. Therefore, the present invention can improve planarization of the conditioner, enhance efficiency, and prolong lifetime.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a chemical mechanical polishing conditioner, especially to a combinational chemical mechanical polishing conditioner having tips of leveling heights. 
         [0003]    2. Description of the Prior Art(s) 
         [0004]    Chemical Mechanical Polishing (abbreviated as CMP) is commonly used in various industries to polish the surfaces of various articles made of ceramic, silicon, glass, quartz, or metal. With the applicability of large-scaled planarization of integrated semiconductor device, CMP becomes a common planarization technique in the semiconductor process. 
         [0005]    During the CMP process of the semiconductor, a pad is contacted with a wafer or other semiconductor elements in conjunction with suitable abrasive slurry to remove impurities or protruding structures on the surface of the wafer through both chemical reaction and mechanical force. When the pad has been used for a period of time, polishing debris produced from the CMP process will accumulate and stagnate on the surface of the pad, thereby reducing the polishing effect and efficiency. Therefore, a chemical mechanical polishing conditioner can be used to dress the surface of the pad for the desired polishing effect and efficiency. 
         [0006]    In the preparation of a chemical mechanical polishing conditioner (abbreviated as CMP conditioner), multiple abrasive particles are mounted to a binding layer to form an abrasive layer. The abrasive layer is fixed to a surface of a substrate by brazing or sintering. Said CMP conditioner is suitable for dressing the pads; however, in more sophisticated semiconductor process with line-width below 45 nanometers, the rough surface of the pad that is too coarse will cause problems such as scratch, local over-polishing, depression, or non-uniform thickness of the wafer. As the line-width of integrated semiconductor device is decreasing, the demand for the planarization of the surface of the wafer is increasing, and same for the CMP conditioner. 
         [0007]    Taiwan Patent Application Publication No. 201341113 discloses a combinational chemical mechanical polishing conditioner comprising a substrate; multiple abrasive units disposed on a surface of the substrate and each abrasive unit comprising multiple abrasive tips and a binder layer fixing the abrasive tips; a thickness-adjustable adhesive layer to fix the abrasive units on the surface of the substrate. A height difference between a first highest point and a second highest point of a predetermined plane is less than 10 micrometers. A height difference between the first highest point and a tenth highest point of the predetermined plane is less than 20 micrometers. A height difference between the first highest point and a hundredth highest point of the predetermined plane is less than 40 micrometers. The first highest point of the predetermined plane protrudes more than 50 micrometers away from the binder layer. This prior invention also relates to the method for preparing the combined chemical mechanical polishing conditioner and the applications of the combinational chemical mechanical polishing conditioner. 
         [0008]    Taiwan Patent Application Publication No. 201249595 discloses a pad conditioner for CMP comprising a substrate having a first set of protrusions and a second set of protrusions. The first set of the protrusions has a first average height and the second set of the protrusions has a second average height. The first average height and the second average height are different. Tops of the protrusions of the first set of the protrusions have protruding surfaces. Tops of the protrusions of the second set of the protrusions have non-flat surfaces. A layer of polycrystalline diamond is disposed on each non-flat surface of the first set of the protrusions and the second set of the protrusions. The protrusions can be discriminated by their heights, predetermined positions, or dimensions of substrates. This prior invention provides various ways to measure the protrusions including an average height measured from a back side of the pad conditioner for CMP, a peak-to-valley height, or a protruding height. However, the protrusions and the substrate are integrated and cannot form a totally planarized surface to improve the abrasive efficiency and prolong lifetime of the CMP conditioner. 
         [0009]    Taiwan Patent Application Publication No. 201341113 discloses a pad conditioner with a uniform height design. However, said invention is different from the present invention to be mentioned afterward in the structure of CMP conditioner. 
         [0010]    To overcome the shortcomings, the present invention provides a CMP conditioner to mitigate or obviate the aforementioned problems. 
       SUMMARY OF THE INVENTION 
       [0011]    The major objective of the present invention is to provide a CMP conditioner by combining abrasive units in smaller dimensions with a substrate in larger dimensions to provide a planarized surface. The planarized surface can improve the polishing effect of the CMP conditioner. 
         [0012]    To achieve the abovementioned objective, the present invention provides a CMP conditioner. The CMP conditioner comprises a substrate, a binding layer disposed on the substrate, and multiple abrasive units placed on the binding layer. Each abrasive unit has an abrasive layer and an abrasive unit substrate. The abrasive layer is a diamond film formed by chemical vapor deposition and has multiple abrasive tips. Heights of the abrasive units are equal to make the CMP conditioner have a planarized surface. Preferably, the CMP conditioner has the abrasive units of equal thicknesses and the binding layer of a fixed thickness to form the planarized surface. Alternatively, the CMP conditioner has the abrasive units having partially equal or different thicknesses and the binding layer of various thicknesses, thereby matching the abrasive units of different thicknesses to form the planarized surface. 
         [0013]    The heights of the abrasive units of the present invention are equal. However, due to the slight precision error during the manufacturing process, a height difference between any two of the abrasive units possibly exists. The height difference between any two of the abrasive units is less than 20 micrometers, preferably 10 micrometers, which can be achieved by controlling the manufacturing process. 
         [0014]    Shape of the abrasive tips of the present invention can be customized by the need of users or the polishing condition. The abrasive tips are in the shape of, but not limited to, knife edges, cones, arcs, cylinders, pyramids, or prisms. Preferably, the abrasive tips are in the shape of pyramids. Alternatively, the abrasive tips are in the shape of prisms. Alternatively, the abrasive tips are cylindrical in shape. 
         [0015]    Alignment directions or tip angles of the abrasive tips of the present invention can be customized by the need of users or the polishing condition. The alignment directions of the abrasive tip are uniform, partially uniform, or different. Preferably, the abrasive tips are perpendicular to a pad. Alternatively, the abrasive tips are non-perpendicular to the pad. 
         [0016]    The tip angles of the abrasive tip are equal, partially equal, or different. Preferably, the tip angles of the abrasive tips are 60 degrees, 90 degrees, or 120 degrees. Alternatively, the tip angles of some of the abrasive tips are 60 degrees and the tip angles of the other abrasive tips are 90 degrees. 
         [0017]    Besides, horizontal distances between any two neighboring abrasive tips of the present invention can be customized by the need of users or the polishing condition. The horizontal distances between any two neighboring abrasive tips are equal, partially equal, or different. Preferably, the horizontal distances between any two neighboring abrasive tips are 1.5 times, 2 times, or 3 times larger than an outer diameter of the abrasive tips. Alternatively, some of the horizontal distances between any two neighboring abrasive tips are 2 times larger than the outer diameter of the abrasive tips and the other of the horizontal distances between any two neighboring abrasive tips are 3 times larger than the outer diameter of the abrasive tips. 
         [0018]    A thickness of the substrate of the present invention and the thicknesses of the abrasive units can be customized by the need of users or the polishing condition. The thickness of the substrate ranges from 10 millimeters (abbreviated as mm) to 200 mm. Preferably, the thickness of the substrate ranges from 60 mm to 100 mm. More preferably, the thickness of the substrate is 80 mm. The thicknesses of the abrasive units are equal, partially equal, or different. Preferably, the thicknesses of the abrasive units range from 5 mm to 100 mm. More preferably, the thicknesses of the abrasive units range from 15 mm to 30 mm. In the best condition, the thicknesses of the abrasive units are 20 mm. 
         [0019]    Preferably, a middle layer is disposed between the abrasive layer and the abrasive unit substrate. The middle layer is made of the group consisting of aluminum oxide, silicon carbide, and aluminum nitride. More preferably, the middle layer is silicon carbide. 
         [0020]    The middle layer of the present invention can be formed by, but is not limited to, chemical vapor deposition, physical vapor deposition, soldering, or brazing. 
         [0021]    The abrasive layer of the present invention is made of monocrystalline diamond or polycrystalline diamond. Preferably, the abrasive layer is made of polycrystalline diamond and a crystal dimension of the abrasive layer ranges from 5 nanometers to 50 micrometers. More preferably, the crystal dimension of the abrasive layer ranges from 10 nanometers to 20 micrometers. The abrasive unit substrate of the present invention is a conductive substrate or an insulating substrate. The conductive substrate is made of molybdenum, tungsten, or tungsten carbide. A patterned surface with multiple surface tips can be formed on the conductive substrate by electric discharge machining and the abrasive layer are successively formed on the surface tips by chemical vapor deposition to obtain the abrasive tips. Alternatively, a patterned surface with multiple surface tips can be formed on the insulating substrate by mechanical polishing or laser processing, and the abrasive layer are successively formed on the surface tips by chemical vapor deposition to obtain the abrasive tips. Alternatively, a surface of the abrasive unit substrate is flat. The abrasive layer is deposited on the abrasive unit substrate by chemical vapor deposition and has multiple abrasive tips. The insulating substrate is made of ceramic material or monocrystalline material. Preferably, the ceramic material is silicon carbide. The monocrystalline material is silicon or aluminum oxide. 
         [0022]    The binding layer of the present invention can be customized by the need of users or the polishing condition. The binding layer is made of, but not limited to, ceramic material, brazing material, electroplating material, metallic material, or polymeric material. Preferably, the binding layer is made of brazing material. The brazing material is made of the group consisting of iron, cobalt, nickel, chromium, manganese, silicon, aluminum, or any combination thereof. Alternatively, the binding layer is made of polymeric material. The polymeric material is epoxy resin, polyester resin, polyacrylate resin, or phenol resin. 
         [0023]    A component or a dimension of the substrate of the present invention can be customized by the need of users or the polishing condition. The substrate is stainless steel substrate, die steel substrate, metal alloy substrate, ceramic substrate, plastic substrate, or any combination thereof. Preferably, the substrate is stainless steel substrate. 
         [0024]    Preferably, the substrate is a flat substrate or a notch substrate. More preferably, the substrate is the flat substrate. Alternatively, the substrate is the notch substrate. 
         [0025]    The polishing effect of the CMP conditioner of present invention is achieved by using the abrasive units of equal thicknesses and the binding layer of a fixed thickness to form the planarized surface, or using the abrasive units having partially equal or totally different thicknesses and the binding layer with various thicknesses, thereby matching the abrasive units of different thicknesses to form the planarized surface. The planarized surface can improve the polishing effect of the CMP conditioner. 
         [0026]    Other objectives, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0027]      FIG. 1  is a side view of a CMP conditioner in accordance with Embodiment 1 of the present invention; 
           [0028]      FIG. 2  is a side view of a CMP conditioner in accordance with Embodiment 2 of the present invention; 
           [0029]      FIG. 3  is a top view of a CMP conditioner in accordance with Embodiment 1 of the present invention; 
           [0030]      FIG. 4A  is a top view of an abrasive unit of a CMP conditioner in accordance with Embodiment 1 of the present invention; 
           [0031]      FIG. 4B  is a top view of an abrasive unit of a CMP conditioner in accordance with Embodiment 3 of the present invention; and 
           [0032]      FIG. 4C  is a top view of an abrasive unit of a CMP conditioner in accordance with Embodiment 4 of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Embodiment 1 
       [0033]    With reference to  FIG. 1 , the present invention provides a chemical mechanical polishing conditioner  1 . The chemical mechanical polishing conditioner  1  comprises a substrate  10 , a binding layer  11 , and multiple abrasive units  12 . The substrate  10  is made of stainless steel. The substrate  10  is a flat substrate and has a thickness of 80 mm. The binding layer  11  is disposed on the substrate  10 . The abrasive units  12  are annularly placed on the binding layer  11 ; in other words, the abrasive units  12  are fixed on the substrate  10  via the binding layer  11 . Thicknesses of the abrasive units  12  are equal. Each abrasive unit  12  has an abrasive unit substrate  13  and an abrasive layer  14 . The abrasive unit substrate  13  is a ceramic substrate made of silicon carbide. A surface of the abrasive unit substrate  13  is a patterned surface with multiple surface tips, and the abrasive layer  14  is successively formed on the surface tips by chemical vapor deposition to obtain abrasive tips. The abrasive tips are in the shape of pyramids. Specifically, with reference to  FIG. 4A , the abrasive tips are continuously arranged on the abrasive unit substrate  13  with an array pattern. The abrasive tips are in the shape of quadrangular pyramids. Alignment directions of the abrasive tips are uniform. Tip angles of the abrasive tips are equal. The abrasive units  12  are fixed on the substrate  10  through the binding layer  11 . In addition, heights of the abrasive units  12  are equal to make the chemical mechanical polishing conditioner  1  have a planarized surface. Due to the slight precision error during manufacturing process, a height difference between any two of the abrasive units  12  is less than 10 micrometers. 
         [0034]    With reference to  FIG. 3 , the abrasive units  12  with equal heights are on the substrate  10  and the binding layer  11 . Each abrasive unit  12  comprises the abrasive unit substrate  13  and the abrasive layer  14 . The abrasive tips are in the shape of pyramids. Besides, the abrasive units  12  are annularly placed on the binding layer  11 . Said height of the abrasive units  12  is the shortest distance between the abrasive tip and a bottom surface of the substrate  10 . Said thickness of the abrasive units  12  is the shortest distance between the abrasive tip and a bottom surface of the abrasive unit substrate  13 . 
       Embodiment 2 
       [0035]    With reference to  FIG. 2 , the CMP conditioner in Embodiment 2 is similar with the CMP conditioner in Embodiment 1. The difference between the two embodiments is that the thicknesses of the abrasive units  22  of Embodiment 2 are partially equal. The heights of the abrasive unit  22  are still equal; that is to say, the chemical mechanical polishing conditioner also has a planarized surface. The planarized surface is achieved by controlling a thickness of the binding layer  21  to match the abrasive units  22  having partially equal thicknesses. 
         [0036]    The CMP conditioner of the present embodiment comprises the substrate  20 , the binding layer  21 , and the abrasive units  22 . The substrate  20  is made of stainless steel. The substrate  20  is a flat substrate and has a thickness of 80 mm. The binding layer  21  is disposed on the substrate  20 . The abrasive units  22  are placed on the binding layer  21 ; in other words, the abrasive units  22  are fixed on the substrate  20  through the binding layer  21 . The abrasive unit substrate  23  is a ceramic substrate made of silicon carbide. The abrasive unit substrates  23  have two different thicknesses, 20 mm and 30 mm. The surface of the abrasive unit substrate  23  is flat. The abrasive layer  24  is deposited on the abrasive unit substrate  23  by chemical vapor deposition. The abrasive layer  24  has the abrasive tips. The abrasive tips are in the shape of pyramids, more specifically, quadrangular pyramids (such as  FIG. 4A ). The abrasive tips are continuously arranged on the abrasive unit substrate  23  with an array pattern. The alignment directions of the abrasive tips are uniform. The tip angles of the abrasive tip are equal. The abrasive units  22  are fixed on the substrate  20  through the binding layer  21 . The planarized surface of the chemical mechanical polishing conditioner is achieved by controlling the binding layer  21  to match the abrasive units  22 . 
       Embodiment 3 
       [0037]    The CMP conditioner in Embodiment 3 is similar to the CMP conditioner in Embodiment 1. The difference between the two embodiments is that the abrasive tips of the CMP conditioner in Embodiment 1 are in the shape of pyramids and the abrasive tips of the CMP conditioner in Embodiment 3 are in different shape to the abrasive tips of the CMP conditioner in Embodiment 1. 
         [0038]    With reference to  FIG. 4A , the abrasive tips of the CMP conditioner in Embodiment 1 are in the shape of pyramids and the abrasive tips are continuously arranged on the abrasive unit substrate  13  with an array pattern. With reference to  FIG. 4B , the abrasive tips  35  of Embodiment 3 are in the shape of prisms, specifically, quadrangle prism. The abrasive tips  35  of the abrasive layer  34  are continuously arranged on the abrasive unit substrate  33  with an array pattern. 
       Embodiment 4 
       [0039]    The CMP conditioner in Embodiment 4 is similar to the CMP conditioner in Embodiment 1. The difference between the two embodiments is that the abrasive tips of the CMP conditioner in Embodiment 1 are in the shape of pyramids and the abrasive tips of the CMP conditioner in Embodiment 3 are in different shape to the abrasive tips of the CMP conditioner in Embodiment 1. 
         [0040]    With reference to  FIG. 4A , the abrasive tips of the CMP conditioner in Embodiment 1 are in the shape of pyramids and the abrasive tips are continuously arranged on the abrasive unit substrate  13  with an array pattern. With reference to  FIG. 4C , the abrasive tips  45  of Embodiment 4 are cylindrical in shape. The abrasive tips  45  of the abrasive layer  44  are continuously arranged on the abrasive unit substrate  43  with an array pattern. 
         [0041]    Even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and features of the invention, the disclosure is illustrative only. Changes may be made in the details, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.