Patent Grant
9931726
The present disclosure relates generally to an integrated circuit and more particularly to a wafer edge trimming tool.
During some integrated circuit (IC) manufacturing processes, a wafer edge may be trimmed to reduce the likelihood of damage to the wafer during subsequent process steps (e.g., thinning). Typically, wafer edge trimming involves applying downward force to a wafer edge using a blade. However, the use of a blade during wafer edge trimming may introduce a high degree of stress to the wafer, which may cause damage such as wafer peeling, chipping, cracking, and the like.
For a more complete understanding of the present embodiments, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:
The making and using of the present embodiments are discussed in detail below. It should be appreciated, however, that the present disclosure provides many applicable inventive concepts that can be embodied in a wide variety of specific contexts. The specific embodiments discussed are merely illustrative of specific ways to make and use the disclosed subject matter, and do not limit the scope of the different embodiments.
In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. Moreover, the formation of a feature on, connected to, and/or coupled to another feature in the present disclosure that follows may include embodiments in which the features are formed in direct contact, and may also include embodiments in which additional features may be formed interposing the features, such that the features may not be in direct contact. In addition, spatially relative terms, for example, “lower,” “upper,” “horizontal,” “vertical,” “above,” “over,” “below,” “beneath,” “up,” “down,” “top,” “bottom,” etc. as well as derivatives thereof (e.g., “horizontally,” “downwardly,” “upwardly,” etc.) are used for ease of the present disclosure of one features relationship to another feature. The spatially relative terms are intended to cover different orientations of the device including the features.
Various embodiments include using an abrasive tape in lieu of a blade to perform edge trimming on various wafers. Edges of a semiconductor wafer may be rotated against the abrasive tape as downward pressure is applied to the abrasive tape, holding a portion of the abrasive tape in position. The rotation of the semiconductor wafer against the rough surface of the abrasive tape has the same effect as a blade in conventional wafer edge trimming techniques without applying high-stress to the wafer.
Holding module 104 holds and dispenses abrasive tape 102 under a polishing head 108. As illustrated, in
As wafer 112 is rotated by the rotation module 110 against abrasive tape 102, polishing head 108 applies downward force to abrasive tape 102. The downward force positions abrasive tape 102 against edge portions of the wafer 112 for edge trimming. For example, polishing head 108 may apply a downward force between about 7N to about 9N so that abrasive tape 102 may be held in place against rotating wafer 112. Edges of wafer 112 are trimmed as portions come in contact with and are polished by abrasive tape 102. Thus, edges of wafer 112 may be trimmed without the use of a high-stress inducing blade.
In various embodiments, abrasive tape 102 may be an abrasive material bonded to a base film (sometimes referred to as a base tape). The abrasive material is oriented facing towards the wafer during wafer edge trimming. For example, in
For example, abrasive tape 102 may include diamond powder having a grain size between 0.5 μm to 30 μm that is bonded to a polyester base film with a thickness between 20 μm to 150 μm. In another example, abrasive tape 102 may include a 12 μm thick layer of diamond powder having a 9 μm grain size bonded to a PET base film having a width of 4 mm, a thickness of 125 μm, and a length of 50 m. Because of the abrasive tape 102 may include diamonds or diamond powder, abrasive tape 102 may alternatively be referred to as diamond tape 102.
Holding parts 104A and 104B may be formed of stainless steel, aluminum, or any other suitable material. Polishing head 108 may be formed of silicon carbide (SiC), or any other suitable material and may have dimensions of, for example, about 30 mm in length and 15 mm in width.
In various embodiments, abrasive tape 102 may be stored in a roll and dispensed from disks (e.g., holding parts 104A and 104B) holding the roll. As portions of abrasive tape 102 come in contact with wafer 112, these portions may become worn and require periodic replacement. By storing abrasive tape 102 in a roll on a disk, fresh (i.e., unworn) portions of abrasive tape 102 may be dispensed (i.e., rolled out) automatically as used portions of abrasive tape 102 become worn. The wafer edge trimming process may proceed with minimum interruptions using a fresh portion of abrasive tape 102. That is, the wafer edge trimming process need not be interrupted frequently to replace worn portions of abrasive tape because fresh portions are rolled out automatically.
For example, in various embodiments, holding parts 104A and 104B are rollers holding abrasive tape 102 in position during the wafer edge trimming process. In one example, holding parts 104A may store fresh abrasive tape and holding part 104B roll may store used portions as they become worn. Alternatively, holding parts 104A and 104B are configured in a different shape that hold abrasive tape 102 in position during the wafer trimming process, and worn portions of abrasive tape 102 may be replaced manually as needed.
In step 204, the edge of the wafer is trimmed using the abrasive tape. A polishing head (e.g., polishing head 108) may apply downward force to a portion of the abrasive tape so that it comes in contact against an edge of the wafer. As the rotating module rotates the edge of the wafer against the abrasive tape, the edges are trimmed. In various embodiments, the use of an abrasive tape in lieu of a traditional edge trimming blade subjects the wafer to less stress during the wafer edge trimming process and decreases the likelihood of damage to the wafer.
In various embodiments, the abrasive tape comprises an abrasive material layer bonded to a base film. The abrasive material layer comprises diamond, diamond powder, silica dioxide, cerium oxide, silicon carbide, aluminum oxide, any combination thereof, or any other suitable material. For example, the abrasive material may include a diamond powder having a grain size ranging from about 0.5 μm to 30 μm bonded to a polyethylene terephthalate (PET) or polyester base film.
In accordance with an embodiment, a wafer edge trimming tool includes an abrasive tape and a holding module configured to hold the abrasive tape against portions of an edge of a rotating wafer during a wafer edge trimming process.
In accordance with another embodiment, a method of wafer edge trimming includes rotating a wafer and trimming an edge of the wafer by rotating the edge of the wafer against an abrasive tape.
In accordance with yet another embodiment, a wafer edge trimming tool includes a diamond tape including diamond powder, a holding module, a polishing head configured to hold the diamond tape against an edge of a wafer during a wafer edge trimming process, and a rotation module configured to rotate the wafer, wherein the diamond tape is held over the edge of the wafer by the holding module.
Various embodiments perform the wafer edge trimming process with less stress compared with conventional methods. It has been observed that wafers processed with wafer edge trimming tool 100 showed reduced damage (e.g., edge peeling or cracking) compared to wafers processed with conventional methods. In an example, peak shift data measurements showed wafer edge trimming tool 100 only causing ⅙th the amount of stress to a wafer compared to the stress caused by conventional edge trimming tools using a blade. In another example, crystalline data measurements showed wafer edge trimming tool 100 only causing 1/10th the amount of stress to a wafer compared to the stress caused by conventional edge trimming tools using a blade.
A skilled person in the art will appreciate that there can be many embodiment variations of this disclosure. Although the embodiments and their features have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the embodiments. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, and composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosed embodiments, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed, that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present disclosure.
The above method embodiment shows exemplary steps, but they are not necessarily required to be performed in the order shown. Steps may be added, replaced, changed order, and/or eliminated as appropriate, in accordance with the spirit and scope of embodiment of the disclosure. Embodiments that combine different claims and/or different embodiments are within the scope of the disclosure and will be apparent to those skilled in the art after reviewing this disclosure.
This application claims the benefit of U.S. Provisional Application No. 61/759,098, filed on Jan. 31, 2013, entitled “Wafer Edge Trimming Tool Using Abrasive Tape,” and U.S. Provisional Application No. 61/759,076, filed on Jan. 31, 2013, entitled “Wafer Polishing Tool Using Abrasive Tape,” which applications are hereby incorporated herein by reference. This application relates to the following commonly assigned patent application filed on the same date as this application and entitled “Wafer Polishing Tool Using Abrasive Tape,” which application is included herein by reference.
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