Patent Application
20150105006
1. Field
Embodiments of the present invention generally relate to semiconductor device fabrication, and more particularly, to a blade for dicing substrates.
2. Description of the Related Art
Die separation, or dicing, by sawing is the process of cutting a thin film microelectronic substrate into individual devices, such as sliders containing read/write recording devices, with a rotating abrasive saw blade. Dicing by sawing provides versatility in selection of depth and width (kerf) of cut, as well as selection of surface finish, and can be used to saw either partially or completely through a substrate or wafer. Wafer dicing technology has progressed rapidly, and dicing is now commonly used in most front-end thin film packaging operations. Dicing is used extensively for separation of die on thin film integrated circuit wafers.
A wafer's device density is ever increasing to reduce unit costs. As a result of device density increase within a wafer, the channels between devices are continually decreasing. This decreasing in spacing demands that saw blade thickness be reduced. Blades are typically installed into hubs/arbors which support the blade with precision flatness and concentricity. The protrusion of the blade from the support of the hub is used to perform the cutting. The unsupported portion of the blade exposed for cutting dictates the aspect ratio of the blade, which equals to unsupported blade exposure divided by blade thickness. With the constant blade exposure, as the blade thickness decreases, the aspect ratio increases. The larger the aspect ratio of a blade is, the more the stiffness and cutting control degrade. Cutting with a high aspect ratio blade results in reduced cutting performance due to the lower effective blade stiffness and increased vibration.
Therefore, an improved blade is needed.
Embodiments of the present invention generally relate to a blade for isolating devices within a wafer and the method of isolating. The blade has a core material, a cutting material disposed on the core material, and a plating material covering a portion of the core and cutting materials. The edge of the blade is not covered by the plating material. During operation, a portion of the plating material is removed to expose the underlying core and cutting materials based on the wearing of the core and cutting materials at the edge of the blade.
In one embodiment, a blade for isolating devices is disclosed. The blade comprises a core material having a center and a first diameter, a cutting material disposed on the core material, and a plating material disposed on a portion of the core material and the cutting material. The plating material shares a same center with the core material and has a second diameter that is less than the first diameter.
In another embodiment, a blade assembly for isolating devices is disclosed. The blade assembly comprises a spindle hub and a blade coupled to the spindle hub. The blade comprises a core material having a center and a first diameter, a cutting material disposed on the core material, and a plating material disposed on a portion of the core material and the cutting material. The plating material shares a same center with the core material and has a second diameter that is less than the first diameter.
In another embodiment, a method for making a blade is disclosed. The method comprises depositing a cutting material on two sides of a core material, and depositing a plating material on the two sides of the core material. The plating material covers the core and the cutting materials. The method further comprises removing a portion of the plating material to expose underlying cutting and core materials.
So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.
To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements disclosed in one embodiment may be beneficially utilized on other embodiments without specific recitation.
In the following, reference is made to embodiments of the invention. However, it should be understood that the invention is not limited to specific described embodiments. Instead, any combination of the following features and elements, whether related to different embodiments or not, is contemplated to implement and practice the invention. Furthermore, although embodiments of the invention may achieve advantages over other possible solutions and/or over the prior art, whether or not a particular advantage is achieved by a given embodiment is not limiting of the invention. Thus, the following aspects, features, embodiments and advantages are merely illustrative and are not considered elements or limitations of the appended claims except where explicitly recited in a claim(s). Likewise, reference to “the invention” shall not be construed as a generalization of any inventive subject matter disclosed herein and shall not be considered to be an element or limitation of the appended claims except where explicitly recited in a claim(s).
Embodiments of the present invention generally relate to a blade for isolating devices within a wafer and the method of isolating. The blade has a core material, a cutting material disposed on the core material, and a plating material covering a portion of the core and cutting materials. The edge of the blade is not covered by the plating material. During operation, a portion of the plating material is removed to expose the underlying core and cutting materials based on the wearing of the core and cutting materials at the edge of the blade.
As the device density increases within a wafer, the channels between devices are getting smaller which leads to thinner cutting portion of saw blades. As the cutting portion 112 gets thinner, the blade aspect ratio increases if the blade exposure, indicated as “D” in
To maintain a low aspect ratio while increase the service time of the blade, the plating material 108 is deposited on both sides of the core material 102 covering a portion of both the core material 102 and the cutting material 104. The plating material 108 may be much thicker than the core material 102, thus providing support and desired stiffness. Conventional blade support such as spacers may not be needed as a result. During operation, a portion of the plating material 108 may be removed to expose the underlying core material 102 and cutting material 104 as the blade exposure decreases due to wearing. The portion of the plating material 108 may be removed as a result of contacting the material that is being cut, or may be removed by a dressing stick, such as an aluminum oxide stick. The wearable plating material 108 provides support for the thin cutting portion 112 and provides a way to control the blade exposure. The blade exposure may be maintained at a minimum length, leading to a low aspect ratio.
In one embodiment, the thickness (into the paper) of the cutting portion 112 is about 50 to 70 micrometers (μm) and the thickness (into the paper) of the plating material 108 is over 200 μm, so the thickness of the blade 100 at an area with the plating material 108 is over 250 μm. In one embodiment, the blade exposure is about 1.25 mm and the thickness of the cutting portion 112 is about 50 μm, which leads to an aspect ratio of 25. In another embodiment, the blade exposure is about 1.25 mm and the thickness of the cutting portion is about 70 μm, which leads to an aspect ratio of 17.9. Both embodiments provide a blade having an aspect ratio of less than 30.
Next, at step 404, a plating material is deposited on the core and cutting materials. The plating material covers both sides of the core material and the cutting material deposited on the core material. The plating material may be a material that has good adhesion to the core material and has a slower wearing rate compared to the base material reinforced by the cutting material. In one embodiment, the plating material is the same as the base material. The plating material on both sides of the core material may have a combined thickness that is much greater than the thickness of the core material. The thick plating material provides support and desired stiffness, thus, conventional blade support such as spacers are not needed. In one embodiment, the plating material on both sides of the core material has a combined thickness of over 200 μm.
Next, at step 406, a portion of the plating material at the edge of the blade is removed to expose the underlying core and cutting materials. The removal process may be achieved by any conventional removing process, such as dressing by an aluminum oxide stick. During operation, a portion of the plating material may be further removed to expose the underlying core and cutting materials, as the core and cutting materials at the edge are worn off. The removal of the portion of the plating material during operation may be achieved by dressing or by contacting the plating material with the material being cut. The portion of the plating material may be removed after a single cut or after multiple cuts.
In summary, a blade having a plating material covering a portion of the core and cutting materials is disclosed. The thick plating material provides support for the blade and provides desired mechanical stiffness. The wearable plating material provides a way to maintain a low aspect ratio while increase the service time of the blade.
While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.
