This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2010-236182, filed on Oct. 21, 2010, the entire contents of which are incorporated herein by reference.
In dicing process of a semiconductor wafer, a backside grinding or backside thinning is provided before dicing in order to dice the semiconductor chips into chips easily.
A laser dicing method capable of reducing a street area such as a dicing region is widely used for various semiconductor devices.
The laser dicing method has its difficulty, when a metal film is formed on a backside of a semiconductor wafer, in simultaneously dicing the semiconductor wafer and the backside metal film. For this reason, in the case of an LED (Light Emitting Diode) that is an optical semiconductor element having a backside metal film formed as a high-reflection film, for example, a substrate of the LED is diced with a laser, the backside metal film is formed as the high-reflection film, and then the substrate is divided into chips.
However, this method suffers from problems in an expanding step, such as peeling off of the high-reflection film that is the backside metal film from a chip edge or connecting of the chips to each other.
A more complete appreciation of embodiments of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings.
Various connections between elements are hereinafter described. It is noted that these connections are illustrated in general and, unless specified otherwise, may be direct or indirect and that this specification is not intended to be limiting in this respect.
Embodiments of the present invention will be explained with reference to the drawings as next described, wherein like reference numerals designate identical or corresponding parts throughout the several views.
First, description is given of a method for manufacturing a semiconductor device and the semiconductor device according to a first embodiment of the present invention with reference to the drawings.
In the method for manufacturing a semiconductor device, as shown in
After attaching the semiconductor wafer holding member 11, the semiconductor wafer 30 is held by vacuum suction and subjected to backside polishing and backside mirror-like finishing using a semiconductor wafer backside polishing apparatus (not shown). This step allows the wafer to be polished for the thickness of a backside grinding region 12, thereby thinning the semiconductor wafer 30.
Next, as shown in
Thereafter, the pattern shape of the element region 2 is observed from the backside for positioning, and then laser dicing is performed by applying a laser beam onto the second main surface (back side) of the semiconductor wafer 30. The semiconductor wafer 30 is divided into semiconductor chips 3 by the laser dicing. It is preferable that a laser capable of reducing debris or airborne matter and having a short pulse of picosecond or less and a wavelength of 355 nm, which is three times longer than that of an Nd:YAG laser, for example, is used as the laser beam.
Although the laser dicing is used here, the semiconductor wafer 30 may be divided into the semiconductor chips 3 by tearing (separating) using a modifying layer formed by focusing the laser beam inside the semiconductor wafer 30, instead. Moreover, dicing may be performed using a laser microjet method. Furthermore, a front-side protecting member may be used instead of the semiconductor wafer holding member 11. In this case, a step of transferring the protecting member can be omitted, thereby enabling reduction in the number of steps.
Subsequently, as shown in
Thereafter, as shown in
By contrast, when the expanding step is performed using a pressing part 15 having a flat surface, peeling off of the backside metal film 14 that is the high-reflection film, pairing in which the chips are connected to each other, or the like occurs. This leads to reduction in yield of the semiconductor backside processing or deterioration in quality of the semiconductor chip as the semiconductor device.
In the first embodiment, the force applied in the oblique direction to the backside metal film 14 formed as the high-reflection film makes the backside metal film 14 easy to break. As a result, peeling off of the backside metal film 14 or pairing can be significantly reduced, and thus desired backside reflection intensity can be secured.
Next, the shape of the semiconductor chip formed is described with reference to
In the comparative example, as shown in
As a result, the backside metal film 14 has its end provided on the inner side by a distance W1 from the ends of the substrate 1 and element region 2. The comparative example requires the steps of forming a resist film and of etching the backside metal film 14, leading to an increase in the number of steps and in a street area.
On the other hand, in the first embodiment, the substrate 1, the element region 2 and the backside metal film 14 have their ends aligned as shown in
As described above, in the method for manufacturing a semiconductor device and the semiconductor device according to the first embodiment, the element region 2 is protected by the front-side protecting member 13 after backside polishing of the semiconductor wafer 30, and then laser dicing is performed by applying the laser beam from the back side of the semiconductor wafer. After the laser dicing, the backside metal film 14 is formed, and then the pressing part 15 is pressed against the front-side protecting member 13 to apply force in the oblique direction to the backside metal film 14, thereby tearing (separating) the backside metal film 14.
As a result, peeling off of the backside metal film 14 formed as the high-reflection film, pairing in which the chips are connected to each other, or the like can be significantly prevented from occurring. Thus, desired backside reflection intensity can be secured.
Note that although the laser dicing is performed from the second main surface (back side) of the substrate 1 in the first embodiment, the present invention is not necessarily limited thereto. For example, as shown in
Furthermore, although the front-side protecting member 13 is expanded by pressing the pressing part 15 against the front-side protecting member 13 after the backside metal film 14 is formed on the second main surface (back side) of the substrate 1 in the first embodiment, the present invention is not necessarily limited thereto. For example, as shown in
Next, description is given of a method for manufacturing a semiconductor device and the semiconductor device according to a second embodiment of the present invention with reference to the drawings.
Hereinafter, the same constituent parts as those of the first embodiment are denoted by the same reference numerals, and only different parts are described while description of the same parts is omitted.
As shown in
Next, as shown in
Next, the shape of the semiconductor chip formed is described with reference to
As shown in
As described above, in the method for manufacturing a semiconductor device and the semiconductor device according to the second embodiment, the element region 2 is protected by the front-side protecting member 13 after backside polishing of the semiconductor wafer 30, and then laser dicing is performed by applying a laser beam from the back side of the semiconductor wafer. After the laser dicing, the front-side protecting member 13 is pre-expanded in the horizontal direction for a predetermined amount. After the pre-expanding, the backside metal film 14 is formed, and then the pressing part 15 is pressed against the front-side protecting member 13 to apply force in an oblique direction to the backside metal film 14, thereby tearing (separating) the backside metal film 14.
As a result, peeling off of the backside metal film 14 formed as the high-reflection film, pairing in which the chips are connected to each other, or the like can be significantly prevented from occurring. Thus, desired backside reflection intensity can be secured.
Note that the embodiments described above are applied to the semiconductor backside processing for dividing a semiconductor wafer into individual LED pieces, but they may be applied instead to a semiconductor element or semiconductor integrated circuit having a backside metal film.
While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modification as would fall within the scope and spirit of the inventions.
Number | Date | Country | Kind |
---|---|---|---|
2010-236182 | Oct 2010 | JP | national |