Patent Application
20150306728
One or more embodiments of the present invention pertain to processing substrates such as those used for the fabrication of electronic devices, optoelectronic devices, optical devices, transistors, and/or integrated circuits.
The present inventors have made one or more discoveries that may be pertinent to processing the surface of substrates using processes such as, but not limited to, polishing and lapping.
One aspect of the present invention pertains to a substrate holder for a first substrate and a second substrate.
Another aspect of the present invention pertains to a system comprising a substrate holder for processing substrates.
Another aspect of the present invention pertains to a method comprising using a substrate holder for processing substrates.
It is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description. The invention is capable of other embodiments and of being practiced and carried out in various ways. In addition, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting.
Skilled artisans appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding embodiments of the present invention.
In the following description of the figures, identical reference numerals have been used when designating substantially identical elements or processes that are common to the figures.
For the following defined terms, these definitions shall be applied, unless a different definition is given in the claims or elsewhere in this specification. All numeric values are herein defined as being modified by the term “about,” whether or not explicitly indicated. The term “about” generally refers to a range of numbers that a person of ordinary skill in the art would consider equivalent to the stated value to produce substantially the same properties, function, result, etc. A numerical range indicated by a low value and a high value is defined to include all numbers subsumed within the numerical range and all subranges subsumed within the numerical range. As an example, the range 10 to 15 includes, but is not limited to, 10, 10.1, 10.47, 11, 11.75 to 12.2, 12.5, 13 to 13.8, 14, 14.025, and 15.
For the present disclosure, the term “substrate” refers to a workpiece for processes, apparatuses, and/or systems according to one or more embodiments of the present invention. The substrate is a solid at ambient conditions. The substrate may be used for applications such as, but not limited to, forming and/or supporting devices such as integrated circuits, electronic devices, optical devices, optoelectronic devices, and for other uses. Examples of substrates include, but are not limited to, wafers, semiconductor wafers, silicon wafers, compound semiconductor wafers, aluminum oxide wafers, sapphire wafers, and quartz wafers.
The term “work surface” as used herein is defined as a surface of the substrate that is being or will be processed such as by polishing, lapping, or grinding.
The term “horizontal” as used herein is defined as a plane parallel to the plane or surface of the substrate or surface of the wafer, regardless of its orientation. The term “vertical” refers to a direction perpendicular to the horizontal as just defined. Terms, such as “above”, “below”, “bottom”, “top”, “side” (as in “sidewall”), “higher”, “lower”, “upper”, “over”, and “under”, are defined with respect to the horizontal plane. The term “on” means there is direct contact among elements.
Flatness is quantified in part by a Total Thickness Variation measurement (TTV) and/or Site Total Indicated Reading (STIR). TTV is the difference between the maximum and minimum thicknesses of the wafer. STIR is the sum of the maximum positive and negative deviations of the surface in a small area of the wafer from a reference plane which is parallel to the back surface of the wafer and intersects the front surface at the center of the local site. Total thickness variation in the wafer is an indicator of the quality of the polish of the wafer.
The order of execution or performance of the operations or the processes in embodiments of the invention illustrated and described herein is not essential, unless otherwise specified. That is, the operations or the processes may be performed in any order, unless otherwise specified, and embodiments of the invention may include additional or fewer operations or processes than those disclosed herein. For example, it is contemplated that executing or performing a particular operation or process before, contemporaneously with, or after another operation or process is within the scope of aspects of the invention.
Embodiments of the present invention will be discussed below primarily in the context of polishing or lapping substrates such as semiconductor wafers used for fabricating electronic devices, optoelectronic devices, and/or optical devices for applications such as, but not limited to, integrated circuits, light emitting diodes, high brightness light emitting diodes, transistors, and high-power transistors; however, it is to be understood that embodiments in accordance with the present invention may be used for other types of substrates, materials other than semiconductors, and processes other than polishing or lapping.
One or more embodiments of the present invention pertain to methods and/or apparatus for increasing the usage of substrate processing systems designed for simultaneous double side processing of substrates for processes such as polishing and lapping. Systems used for simultaneous double-side polishing or lapping substrates are configured so as to hold one or more substrates between two polishing or lapping surfaces so that both sides of the substrate are polished or lapped. According to one or more embodiments of the present invention, a system designed for simultaneous double side processing of substrates is converted to processing a single side of the substrates using a substrate holder according to one or more embodiments of the present invention. Consequently, a system designed for simultaneous double side processing of substrates can be used for either single side processing, which can also have a high substrate throughput, or double-side processing of substrates by using substrate holders according to embodiments of the present invention or standard substrate holders, respectively.
Reference is now made to
According to one embodiment of the present invention, substrate holder 12 is disk shaped. More specifically, substrate holder 12 has a substantially circular periphery which may result from having an actual circular outer diameter or an outer diameter defined by multiple flat sides such as for, but not limited to, a pentagon, hexagon, octagon, etc., which approximate a circular diameter. According to one or more embodiments of the present invention, the width or the outer diameter of substrate holder 12 is greater than the diameter of the first substrate and of the second substrate. In other words, the outer edge of substrate holder 12 extends beyond the outer edge of the substrates sufficiently to reduce possible physical damage to the edge of the substrate that could result from contact with other objects, such as, but not limited to, other substrate holders, other substrates, and barriers of processing systems like walls.
Substrate holder 12 may be made of a variety of materials. According to one embodiment of the present invention, substrate holder 12 is metallic and comprises a metal or a metal alloy. According to one or more embodiments of the present invention, substrate holder 12 comprises material such as, but not limited to, aluminum, aluminum alloy, nickel, nickel alloy, molybdenum, molybdenum alloy, steel, stainless steel, titanium, titanium alloy, tantalum, tantalum alloy, or combinations thereof. According to one or more embodiments of the present invention, substrate holder 12 comprises material such as but not limited to polymer, plastic, ceramic, and/or other non-metallic materials.
According to one or more embodiments of substrate holder 12, first recessed area 26 and the second recessed area 28 may have shapes and dimensions to accommodate a variety of substrate sizes. Generally, first recessed area 26 and second recessed area 28 are shaped and sized so that the substrates can be placed in the recessed area. According to one embodiment of the present invention, the depth of first recessed area 26 is not greater than the thickness of the first substrate prior to lapping or polishing and the depth of the second recessed area 28 is not greater than the thickness of the second substrate prior to lapping or polishing.
Another embodiment of the present invention is a substrate holder for a first substrate and a second substrate, the first substrate and the second substrate each have a work surface. The substrate holder comprises a metal disk-shaped body having a first side and a second side on opposite sides of the body. The first side has a first recessed area sized to receive the first substrate. The depth of the first recessed area is selected to be not greater than the thickness of the first substrate. The second side has a second recessed area sized to receive the second substrate. The depth of the second recessed area is selected to be not greater than the thickness of the second substrate. The substrate holder holds the first substrate on the first side and the second substrate on the second side so that the work surface of the first substrate faces away from and is parallel to the work surface of the second substrate.
Substrate holder 12, such as that described in
One aspect of the present invention pertains to a system for processing a surface of substrates using processes such as polishing or lapping.
First polishing or lapping tool 62 and second polishing or lapping tool 82 are spaced apart and disposed opposite so that they face each other and are parallel to each other so as to form a polishing or lapping zone to receive the least one substrate holder 12. In other words, the polishing zone is bounded at least in part by the polishing or lapping surface of first polishing or lapping tool 62 and by the polishing or lapping surface of second polishing or lapping tool 82. The at least one substrate holder 12 has a first substrate 30 on first surface 22 and a second substrate 34 on second surface 24; they are placed between first polishing or lapping tool 62 and second polishing or lapping tool 82. Work surface 32 of first substrate 30 contacts the polishing or lapping surface of first polishing or lapping tool 62. Work surface 36 of second substrate 34 contacts the polishing or lapping surface of second polishing or lapping tool 82 so that simultaneous polishing or lapping of work surface 32 of first substrate 30 and work surface 36 of second substrate 36 is effected by rotating first polishing or lapping tool 62 and/or rotating second polishing or lapping tool 82.
According to one or more embodiments of the present invention, rotary coupling 58 imparts rotary motion to first polishing or lapping tool 62 and rotary coupling 78 imparts rotary motion to second polishing or lapping tool 82.
Reference is now made to
According to one or more embodiments of the present invention, such as the embodiments illustrated in
Reference is now made to
As an option, system 50 may further comprise a distributor (distributor not shown in figures) to provide a slurry such as a chemical mechanical polishing slurry, an abrasive material, an etchant, a lubricant such as oil or other materials that may be used for polishing and/or lapping processes.
As an option for system 50, the substrates can be releasably attached to the substrate holder with a binder applied between the substrate holder and the substrate. The binder may be a material such as an adhesive, such as a resin, such as a wax, or other material.
Another aspect of the present invention pertains to a method of simultaneously processing a work surface of a first substrate and a work surface of a second substrate using processes such as polishing or lapping. One embodiment of the present invention comprises a method which comprises providing a substrate holder 12 substantially as described above. The method comprises providing an apparatus having a first polishing or lapping surface and a second polishing or lapping surface disposed opposite and parallel to the first polishing or lapping surface. The method comprises disposing the first substrate in contact with the first side of the substrate holder and disposing the second substrate in contact with the second side of the substrate holder. The method also comprises contacting the first polishing surface with the work surface of the first substrate while the first substrate is held on the first side of the holding surface to polish or lap the first substrate while also contacting the second polishing surface with the work surface of the second substrate while the second substrate is held with the second holding surface to polish or lap the second substrate.
The method further comprises rotating the first polishing or lapping surface while contacting the first substrate and/or rotating the second polishing or lapping surface while contacting the second substrate.
According to one or more embodiments of the present invention, the method comprises rotating the first polishing or lapping surface while contacting the first substrate and rotating the second polishing or lapping surface while contacting the second substrate, and allowing momentum transferred from the first polishing or lapping surface and the second polishing or lapping surface to freely rotate and/or spin the substrate holder and the substrate.
As an option for one or more embodiments of the present invention, the method may further comprise using a slurry such as a chemical mechanical polishing slurry; an abrasive material; an etchant, a lubricant such as oil or other materials that may be used for polishing and/or lapping processes.
A variety of substrates can be processed by methods according to embodiments of the present invention. According to one embodiment of the present invention, the method includes the first substrate and the second substrate comprising semiconductor wafers for fabricating electronic and/or optical devices. According to another embodiment of the present invention, the method includes the first substrate and the second substrate comprising silicon wafers for fabricating electronic devices.
Wafers produced according to one or more embodiments of the present invention meet predetermined specifications for properties such as TTV and roughness. Typically, wafers produced according to one or more embodiments of the present invention have total thickness variation of about 1 μm (for 100 mm to 200 mm diameter wafers) and surface roughness of about 0.1-0.3 nanometers.
Wafer holders according to one or more embodiments of the present invention can be used with a variety of simultaneous double-side substrate processing systems. Examples of possible double side substrate processing systems suitable for one or more embodiments of the present invention include, but are not limited to, systems described in U.S. Pat. No. 6,062,949, U.S. Pat. No. 6,113,478, U.S. Pat. No. 6,227,944, and U.S. Pat. No. 6,296,553. The content of U.S. Pat. No. 6,062,949, U.S. Pat. No. 6,113,478, U.S. Pat. No. 6,227,944, and U.S. Pat. No. 6,296,553 are incorporated herein by this reference for all purposes.
In the foregoing specification, the invention has been described with reference to specific embodiments; however, one of ordinary skill in the art appreciates that various modifications and changes can be made without departing from the scope of the present invention as set forth in the claims below. Accordingly, the specification is to be regarded in an illustrative, rather than a restrictive sense, and all such modifications are intended to be included within the scope of the present invention.
Benefits, other advantages, and solutions to problems have been described above with regard to specific embodiments; however, the benefits, advantages, solutions to problems, and any element(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential feature or element of any or all the claims.
As used herein, the terms “comprises,” “comprising,” “includes,” “including,” “has,” “having,” “at least one of,” or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, article, or apparatus that comprises a list of elements is not necessarily limited only to those elements, but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Further, unless expressly stated to the contrary, “or” refers to an inclusive or and not to an exclusive or. For example, a condition A or B is satisfied by any one of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present).
