Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
  • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
  • H01L21/02041—Cleaning
  • H01L21/02057—Cleaning during device manufacture
  • H01L21/02068—Cleaning during device manufacture during, before or after processing of conductive layers, e.g. polysilicon or amorphous silicon layers
  • H01L21/02074—Cleaning during device manufacture during, before or after processing of conductive layers, e.g. polysilicon or amorphous silicon layers the processing being a planarization of conductive layers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B08—CLEANING
  • B08B—CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
  • B08B1/00—Cleaning by methods involving the use of tools
  • B08B1/10—Cleaning by methods involving the use of tools characterised by the type of cleaning tool
  • B08B1/12—Brushes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B08—CLEANING
  • B08B—CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
  • B08B1/00—Cleaning by methods involving the use of tools
  • B08B1/30—Cleaning by methods involving the use of tools by movement of cleaning members over a surface
  • B08B1/32—Cleaning by methods involving the use of tools by movement of cleaning members over a surface using rotary cleaning members
  • B08B1/34—Cleaning by methods involving the use of tools by movement of cleaning members over a surface using rotary cleaning members rotating about an axis parallel to the surface
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
  • B24B37/00—Lapping machines or devices; Accessories
  • B24B37/34—Accessories
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
  • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
  • H01L21/02041—Cleaning
  • H01L21/02096—Cleaning only mechanical cleaning
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
  • H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
  • H01L21/67005—Apparatus not specifically provided for elsewhere
  • H01L21/67011—Apparatus for manufacture or treatment
  • H01L21/67017—Apparatus for fluid treatment
  • H01L21/67028—Apparatus for fluid treatment for cleaning followed by drying, rinsing, stripping, blasting or the like
  • H01L21/6704—Apparatus for fluid treatment for cleaning followed by drying, rinsing, stripping, blasting or the like for wet cleaning or washing
  • H01L21/67046—Apparatus for fluid treatment for cleaning followed by drying, rinsing, stripping, blasting or the like for wet cleaning or washing using mainly scrubbing means, e.g. brushes

Definitions

• the present invention is generally directed to chemical mechanical polishing of substrates. More specifically, the present invention is directed to a brush for cleaning substrates following chemical mechanical polishing. BACKGROUND OF THE INVENTION
• CMP chemical mechanical polishing
• integrated circuit devices are in the form of multi-level structures. At the wafer level, transistor devices having diffusion regions are formed. In subsequent levels, metal interconnect lines are patterned and electrically connected to the transistor devices to define the desired functional device. As is well known, patterned conductive layers are insulated from other conductive layers by dielectric materials, such as silicon dioxide. As more metallization levels and associated dielectric layers are formed, the need to planarize the dielectric material grows. Without planarization, fabrication of further interconnect and dielectric layers becomes substantially more difficult due to the higher variations in the surface topography.
• metal interconnect patterns are formed in a dielectric material on a wafer, and then, chemical mechanical planarization, CMP, operations are performed to remove the excess metal. After any such CMP operation, it is necessary that the planarized wafer be cleaned to remove particulates and contaminants.
• CMP chemical mechanical planarization
• CMP Chemical-mechanical polishing
• the slurries typically are water based and can include fine abrasive particles such as silica, alumina, and other metal oxide abrasive materials.
• cleaning brushes are commonly used. These cleaning brushes are usually cylindrical in shape and are rotated along a center axis of the brush.
• the cleaning brushes are also often made of a foam or porous polymeric material such as polyvinyl alcohol ("PVA").
• PVA polyvinyl alcohol
• Such brushes may be injection molded, such as described in U.S. Patent No. 8,460,475, owned by the owner of the instant application and incorporated herein by reference for all purposes.
• fabrication labs employ cleaning systems.
• the cleaning systems typically include one or more brush boxes in which wafers are scrubbed. Each brush box includes a pair of brushes, such that each brush scrubs a respective side of a wafer.
• TTB fluid delivery is accomplished by implementing brush cores that have a plurality of holes that allow fluids being fed into the brush core at a particular pressure to be released onto the substrate surface. The fluid is distributed from the brush core through the polymeric material and onto the substrate surface.
• brushes have protrusion or nodes on their surface for contact and material removal from a substrate.
• Brushes are formed as sleeves and are slid over a core support which is used to deliver fluids to the brush and to rotate the brush.
• X-ray photoelectron spectroscopy can be used to detect BTA on copper and copper oxide surfaces.
• the area under the XPS nitrogen Is line ( Is line) can be used to determine the presence and amount or relative amount of BTA on a surface and the Cu 2p3/2 line can be used to indicate the presence of copper oxide.
• Decreasing area under the N Is line for a series of XPS spectra following brush cleanings on a substrate with BTA can be used to indicate that BTA is being removed from the substrate.
• the area under the XPS Nls line can be used to compare amounts of BTA on different substrates following cleaning.
• a cylindrical foam brush having a nodule pitch to nodule diameter ratio (P D) of between 1.2 and 1.5 and a nodule height to nodule diameter ratio of 0.2 to 0.5.
• a cylindrical foam brush has a plurality of nodules with a row of elongate nodules at each of two ends and uniformly shaped nodules therebetween, the uniform shaped nodules therebetween having a nodule pitch to nodule diameter ratio (P/D) of between 1.2 and 1.5 and a nodule height to nodule diameter ratio of0.2 to 0.5.
• P/D nodule pitch to nodule diameter ratio
• a cylindrical foam brush has a plurality of nodules with a row of elongate nodules at each of two ends and uniformly shaped nodules therebetween, the uniform shaped nodules therebetween having a nodule pitch to nodule diameter ratio (P D) of between 1.2 and 1.5 and a nodule height to nodule diameter ratio of 0.2 to 0.5.
• P D nodule pitch to nodule diameter ratio
• An advantage of the invention is that improved small particle and organic residue removal from substrates following CMP processing is provided.
• the CMP cleaning brushes can be made of a low compression strength foam.
• a feature and advantage of embodiments is that such CMP cleaning brushes can be used and are effective in a variety of CMP cleaning processes, including post copper CMP processes, to remove small particles and organics from polished substrates.
• FIGURES Figure 1 illustrates various dimensions and features on a post CMP cleaning brush.
• Figure 2 is a side elevation view of a brush in accord with the inventions herein.
• Figure 3 is a detail side elevational view of a nodule.
• Figure 4 is a brush with rows of elongate nodules at the ends of the brush base.
• a CMP cleaning brush 4 has a base 8 with an outer surface 12 and a plurality of nodules 14.
• Each nodule has an outward face 16 and a side wall 19 with a side wall surface 21. The outward face is generally planar but may have a slight convex shape.
• Each nodule has a height h, a nodule axis n.a., a nodule center n.c, and nodule diameter n.d.
• the nodules are arranged such that each nodule has adjacent nodules, defining nodule spacing (N.S.) or "pitch" between the centers of adjacent nodules.
• the pitch then is the distance between centers of the closest adjacent nodule.
• the brush has an inside diameter (ID) and outside diameter (OD).
• ID inside diameter
• OD outside diameter
• the nodules may have a slight taper from adjacent the base to the top of the nodule, see the taper angle ⁇ or angle of variation from cylindrical
• an embodiment with uniformly shaped and spaced nodules that may be substantially cylindrical.
• substantially cylindrical is defined where the diameter varies less than 20% through the length of the nodule.
• the nodule diameter n.d. is defined as the mean of the lesser diameter 25 and the greater diameter 26; with the measurement taken adjacent the top face just below any radiused corner 31 at the top of the nodule and any radiused corner 33 at the bottom of the nodule.
• top implies radially outward
• bottom or lower implies radially inward.
• Table 1 below shows the results of measurements of the pitch, height, and diameter of brush nodules using two different methods. The results show that the two techniques are comparable for similar brushes, for example brush CI measured by the laser camera had a P/D ratio of 1.47 and an H/D ratio of 0.64; a measurement made using a visual technique gave a P/D ratio of 1.44 and an H/D ratio of 0.64. A letter designation for several test brushes, the P/D or H/D ratio, and reported relative qualitative representation of BTA removal by the brush from substrates (poor, fair, good, very good). Table 1.
• the pitch P which is the center to center spacing of the nodules on the brush, can range from 5 millimeters, or about 5 millimeters, to 22 millimeters or about 22 millimeters.
• Some brushes have nodules in rows where the different rows are disposed at spaced, radial locations about the longitudinal axis of the cylindrical body such that projections of one row are disposed at intervals to define an angle of 22.5° between radial lines extending through the central axes of adjacent offset nodules. This 22.5 "angle gives 16 nodules around the circumference. Other angles and numbers of nodules about the brush circumference are also possible.
• the height of the nodules can be measured from the base of the nodule to its top most surface and nodule heights can range from 2 millimeters, or about 2 millimeters, to 8 millimeters or about 8 millimeters.
• the diameter of the nodules can range from 4 millimeters, or about 4 millimeters, to 15 millimeters or about 15 millimeters.
• the diameter of nodules on a brush can be the same or the nodules on the brush can have different diameters; the height of nodules on a brush are all substantially the same; the pitch between nodules on a brush can be the same or different. If different, average pitches of the brush may be used to conform to the inventions herein.
• nodule diameter, nodule to nodule pitch, and nodule height that fall in the nodule pitch to nodule diameter ratio range (P/D) of between 1.2 and 1.5 and the nodule height to nodule diameter ratio range of 0.2 to 0.5 are illustrated in the Table 2 below. Without limitation, other combinations of nodule diameter, nodule to nodule pitch, and nodule height not listed in Table 2 can also be used in versions of the brush. Table 2
• Brush outside diameter can be determined by measuring the distance from the central rotational axis of the brush to the top surface of a nodule and multiplying by two- this can be used to determine an effective outside diameter of the brush even for brushes where nodules are not positioned opposite each other on the brush.
• the outside diameter of the brush or the effective outside diameter of the brush can range from 40 millimeters to 70 millimeters.
• Nodule pitch to nodule diameter ratio (P D) of brush can range from 1.2 to 1.5. If P D is less than 1.2 there is a high risk of scratching the substrate because there is little room between nodules for particles to escape from under the brush nodules. If P/D is greater than 1.5, there is a risk that there will not be sufficient contact area to clean efficiently because there is greater free space on the brush without nodules.
• Nodule height to nodule diameter ratio (H/D) of brush can range from 0.2 to 0.5. If H/D is less than 0.2, essentially more stubby than 0.2 to 0.5, the stress on the wafer from the brush nodule can be greater which can lead to substrate damage. If the P D ratio is greater than 0.5, less shear force will be applied by the nodules to the substrate thereby reducing cleaning efficiency.
• the P/D ratio can be substituted by a P/A (pitch to contact area) ratio and likewise the H/D ratio substituted by an H/A (height to contact area) ratio.
• Nodules in some versions can be substantially cylindrical in cross section, for example the diameter varies by less than ⁇ 20% depending upon where the measurement is taken on a given nodule or set of nodules. The diameter of the external face of the nodule compared to the diameter at the end of the conical section of the nodule, where the nodule transitions to the cylindrical base. In some versions of conical nodules, the diameter can be taken at the top of the nodule.
• the pitch, height, and diameter measurement of nodules can be an average made on 10 or more nodules.
• asymmetrically shaped nodules For irregularly shaped nodules, asymmetrically shaped nodules, the diameter of a circle that circumscribes the irregularly shaped nodule can be used for the diameter. In brush ' configurations, such as illustrated in U.S. Publication US 2013/0048018, incorporated by reference herein, asymmetrically shaped nodules are illustrated.
• the pitch or spacing between adjacent nodules can be measured from the center to center of adjacent nodules, usually nodules in the same row, but nodules may be in a spiral or other configuration.
• the nodules can be in the shape of a cylinder or other geometric shape such as a truncated cone.
• irregularly shaped nodules for example but not limited to those disclosed in International Patent Application No. PCT/US2012/057337, Patel, titled "Post-CMP Cleaning Apparatus and method, filed September 26, 2012 and incorporated herein by reference in its entirety, the approximate center of mass of a cross section can be used to estimate the center of a nodule.
• the height of the nodule can be measured from its top most surface 16 or point to the outer surface 12 of the brush base as illustrated in FIGURE 1.
• the CMP brush has an unbalanced nodule configuration, such as about the center region of the brush or wafer, or as otherwise disclosed in U.S. Patent Publication No. US2013/0048018, incorporated herein by reference in its entirety.
• the nodules on one side of the brush can have a first or first set of P D and H/D ratio(s) while nodules on the other side of the center region can have a second or second set of P/D and H/D ratio(s); the first and second set of P/D and H/D ratios can be the same or different and both sets fall within the nodule pitch to nodule diameter ratio (P D) range of between 1.2 and 1.5 and the nodule height to nodule diameter ratio (H/D) range of 0.2 to 0.5.
• P D nodule pitch to nodule diameter ratio
• H/D nodule height to nodule diameter ratio
• the compressive strength of the foam comprising the brush can be from 60 grams/centimeter squared to 90 grams/centimeter squared.
• a CMP cleaning brush having a compression strength of from 60 grams/centimeter squared to 90 grams/centimeter squared is considered to be a relatively soft brush when compared to brushes that have a foam compression strength of greater than 90 g/cm 2 .
• the brushes have a foam with a compression strength of 90 grams/centimeter squared or less.
• Softer brushes are advantageous in reducing scratches on substrates caused by slurry particle trapped between nodule tops and the substrate, but lower compression strength can reduce brush cleaning efficiency for removing particles and organics like BTA from a substrate.
• a brush with a nodule P/D ratio of from 1.2 to 1.5 and nodule H/D ratio of from 0.2 to 0.5 shows qualitative improvement in cleaning especially with low compression brush foams.
• Brushes can be made for example using the teachings of U.S. Pat. No. 7,984,526, Benson, filed 16, August 2006, and U.S. Pat. No. 8,092,730, Wargo, et al, filed November 21, 2006, the contents of these incorporated herein by reference in their entirety. Brushes can also be made using the teachings of U.S Pat. No. 4,098,728, Rosenblatt, filed Jan. 2, 1976, and U.S. Pat. No. 6,793,612, filed March 24, 2000, the teachings of these incorporated herein by reference in their entirety.
• the brush can have one or two circumferential rows 41 of elongate nodules on one end or on both ends as provided by US 2013/0048018, incorporated by reference herein.
• Brush foam can be PVA (polyvinyl alcohol), polyvinyl acetal, polyurethane, or other materials used to make foam brushes for CMP cleaning.
• PVA polyvinyl alcohol
• polyvinyl acetal polyvinyl acetal
• polyurethane polyurethane
• Compression can be determined by slicing a ring (cross section) sample of the brush, compressing it to 30% of the original height of the ring sample using an Instron, and recording the force to achieve the 30 % height compression.
• Results of brush compression can be reported in grams/cm 2 .
• the nodule attributes disclosed in U.S. Pat. No. 6,793,612 col. 3, lines 30-65 can be used to illustrate brush and nodule configurations that lie outside of the brushes described herein.
• the nodules of U.S. Pat. No. 6,793,612 col. 3, lines 30-65 have a nodule height of about 0.1875 inches (0.476 cm), and a diameter of 0.31 inches (0.78 cm).
• the nodules are disposed at intervals to define an angle of 22.5 between radial lines extending through the projections which would give 16 projection around the diameter of the brush.
• the brush radius would be 3.5 cm and the pitch between nodules calculated to be (2*3.145*(3.5))/16 or 1.37 cm.
• the pitch would be 0.78 cm between nodules.
• compositions and methods are described in terms of “comprising” various components or steps (interpreted as meaning “including, but not limited to”), the compositions and methods can also “consist essentially of or “consist of the various components and steps, such terminology should be interpreted as defining essentially closed or closed member groups.

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• Engineering & Computer Science (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Condensed Matter Physics & Semiconductors (AREA)
• General Physics & Mathematics (AREA)
• Manufacturing & Machinery (AREA)
• Computer Hardware Design (AREA)
• Physics & Mathematics (AREA)
• Power Engineering (AREA)
• Mechanical Engineering (AREA)
• Cleaning Or Drying Semiconductors (AREA)
• Mechanical Treatment Of Semiconductor (AREA)
• Cleaning In General (AREA)
• Brushes (AREA)

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• 2015
  • 2015-02-20 JP JP2016553552A patent/JP6843621B2/ja active Active
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• 2020
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