Wafer edge trimming tool using abrasive tape

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.

TECHNICAL FIELD

The present disclosure relates generally to an integrated circuit and more particularly to a wafer edge trimming tool.

BACKGROUND

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.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

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.

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.

FIG. 1is a schematic diagram of an exemplary wafer edge trimming tool100according to various embodiments. Wafer edge trimming tool100includes an abrasive tape102, a holding module104(having first and a second holding parts104A and104B respectively), a polishing head108, and a rotation module110. A wafer112is placed on rotation module110. Wafer112may be a semiconductor wafer comprising silicon, silicon dioxide, aluminum oxide, sapphire, germanium, gallium arsenide (GaAs), an alloy of silicon and germanium, indium phosphide (InP), and/or any other suitable material.

Holding module104holds and dispenses abrasive tape102under a polishing head108. As illustrated, inFIG. 1, holding module104(holding abrasive tape102) and polishing head108are disposed on an edge region of wafer112. Rotation module110rotates and feeds portions of edges of wafer112under polishing head108and abrasive tape102during the wafer trimming process as indicated by arrow106. For example, rotation module110may rotate wafer112at about 700 rpm. AlthoughFIG. 1illustrates rotation module110rotating wafer112in the clockwise direction indicated by arrow106, rotation module110may also rotate wafer112in the opposite, e.g., counter-clockwise, direction as well.

As wafer112is rotated by the rotation module110against abrasive tape102, polishing head108applies downward force to abrasive tape102. The downward force positions abrasive tape102against edge portions of the wafer112for edge trimming. For example, polishing head108may apply a downward force between about 7N to about 9N so that abrasive tape102may be held in place against rotating wafer112. Edges of wafer112are trimmed as portions come in contact with and are polished by abrasive tape102. Thus, edges of wafer112may be trimmed without the use of a high-stress inducing blade.

In various embodiments, abrasive tape102may 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, inFIG. 1, the abrasive material of abrasive tape102would be oriented facing downward (contacting wafer112) while the base film of abrasive tape102would be oriented facing upward (contacting polishing head108). The abrasive material may be diamond, diamond powder, silica dioxide, cerium oxide, silicon carbide, aluminum oxide, combinations thereof, and the like. The base film may be formed of polyethylene terephthalate (PET), polyester, or the like. Furthermore, abrasive tape102may have a width between 2 mm to 20 mm and a length of 50 m or more.

For example, abrasive tape102may 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 tape102may 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 tape102may include diamonds or diamond powder, abrasive tape102may alternatively be referred to as diamond tape102.

Holding parts104A and104B may be formed of stainless steel, aluminum, or any other suitable material. Polishing head108may 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 tape102may be stored in a roll and dispensed from disks (e.g., holding parts104A and104B) holding the roll. As portions of abrasive tape102come in contact with wafer112, these portions may become worn and require periodic replacement. By storing abrasive tape102in a roll on a disk, fresh (i.e., unworn) portions of abrasive tape102may be dispensed (i.e., rolled out) automatically as used portions of abrasive tape102become worn. The wafer edge trimming process may proceed with minimum interruptions using a fresh portion of abrasive tape102. 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 parts104A and104B are rollers holding abrasive tape102in position during the wafer edge trimming process. In one example, holding parts104A may store fresh abrasive tape and holding part104B roll may store used portions as they become worn. Alternatively, holding parts104A and104B are configured in a different shape that hold abrasive tape102in position during the wafer trimming process, and worn portions of abrasive tape102may be replaced manually as needed.

FIG. 2is a flowchart of an exemplary method using the wafer edge trimming tool illustrated inFIG. 1according to various embodiments. At step202, a rotation module (e.g., rotation module110) rotates a wafer (e.g., wafer112). The wafer is placed on the rotation module and a holding module (e.g., holding module104), holding an abrasive tape (e.g., abrasive tape102), is disposed over an edge of the wafer. The holding module may include a first part and a second part (e.g., holding parts104A and104B) that hold a portion of the abrasive tape in position between the first and the second part of the holding module during the wafer edge trimming process. Furthermore, the first and the second part of the holding module may be rollers that periodically dispense (i.e., roll out) fresh portions of the abrasive tape in position during the wafer edge trimming process. Dispensing fresh portions of the abrasive tape may be necessary as used portions become worn out.

In step204, the edge of the wafer is trimmed using the abrasive tape. A polishing head (e.g., polishing head108) 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 tool100showed 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 tool100only causing ⅙ththe 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 tool100only causing 1/10ththe amount of stress to a wafer compared to the stress caused by conventional edge trimming tools using a blade.

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.