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  Laser scribe on front side of a semiconductor waferUSPTO Application #: 20080090377Title: Laser scribe on front side of a semiconductor wafer Abstract: Disclosed are a semiconductor wafer (10) having a front side laser scribe (22) and the methods for manufacturing the same. The methods of the invention include the formation of a scribe foundation (12) on the front side of the semiconductor wafer (10) designed to accept laser scribing (22), and laser scribing the scribe foundation (12). Disclosed embodiments include a semiconductor wafer (10) having a scribe foundation (12) of layered dielectric (30) and metal (34) on the front side. According to disclosed embodiments of the invention, the formation of a scribe foundation (12) is performed in combination with the formation of a top level metal layer (34) on the semiconductor wafer (10) methods for manufacturing. (end of abstract)
Agent: Texas Instruments Incorporated - Dallas, TX, US Inventor: Byron Joseph Palla USPTO Applicaton #: 20080090377 - Class: 438401000 (USPTO) Related Patent Categories: Semiconductor Device Manufacturing: Process, Formation Of Electrically Isolated Lateral Semiconductive Structure, Having Substrate Registration Feature (e.g., Alignment Mark) The Patent Description & Claims data below is from USPTO Patent Application 20080090377. Brief Patent Description - Full Patent Description - Patent Application Claims
TECHNICAL FIELD [0001] The invention relates to semiconductor device manufacturing. More particularly, the invention relates to semiconductor wafer processing and to methods for making a trackable laser scribe on the front side of a semiconductor wafer. BACKGROUND OF THE INVENTION [0002] Semiconductor device fabrication requires that a semiconductor wafer pass through a number of manufacturing stages. For example, masking, patterning, etching, and film deposition may be performed numerous times in order to manufacture the multiple layers and features of a semiconductor device. The need to track individual wafers through the manufacturing process has given rise to the use of a trackable wafer scribe, typically in the form of a numerical designation readable by both human operators and machines. [0003] Scribing a semiconductor at the beginning of the manufacturing process allows the wafer to be tracked through the remainder of the processing steps. Several problems arise, however with scribing a wafer at the beginning of the manufacturing process. For example, particles and contaminants can collect in the scribed area during a deposition step, then spread to other areas of the wafer during subsequent processing steps. The result is often the formation of unwanted short-circuits, open circuits, and other defects in the completed devices. A common approach to solving these problems is the use of a scribe on the backside of the wafer only, rather than the front side. In fact, it is common for manufacturers of larger semiconductor wafers, e.g. 300 mm, to place scribes exclusively on the backside, rather than on the front as used with 200 mm wafers. [0004] The use of a backside wafer scribe avoids many of the problems associated with the presence of a front side scribe during some manufacturing steps, particularly those performed in the early stages of wafer fabrication, however the utility of backside scribes is limited. One of the primary limitations of the use of backside wafer scribes is that some steps in the wafer fabrication process can operate to eliminate or obscure the scribe. Backside scribes are particularly susceptible to damage or eradication during steps near the end of the wafer fabrication process. For example, following steps for passivation and bond pad formation, further steps are typically performed in preparation for eventual die separation and packaging, including backgrind, resulting in the removal of the scribe. An additional problem encountered is that some testing and packaging equipment is designed for use with wafers having a front side scribe, and upgrading such equipment to read backside scribes can be quite costly. [0005] Due to these and other problems, the application of a front side scribe as late in the wafer fabrication process as possible, but prior to process steps which may interfere with the use of the backside scribe, would be desirable in the arts. Such a front side scribe would permit continuity in tracking wafers until die separation. However, conventional scribing methods are not amenable to scribing the front side of a wafer in the advanced stages of the fabrication process. This is due to the characteristics and materials present on the wafer as it nears completion. For example, the films present on the wafer front side may include dielectrics, metals, and etch-stop materials. As a result, the wafer surface may have inherent variability in thickness and composition, which may be particularly extreme at the edges of the wafer outside of the boundaries of the saleable devices. This variability extends not only to the surface of the individual wafer, but also to variations from wafer to wafer and from lot to lot. This is particularly true at the wafer edge where the front side scribe is commonly applied. The use of typical laser scribing equipment on such surfaces often results in variations in depth, profile and ultimately in readability of the scribe and may also cause contamination of the wafer surface. [0006] Improved front side semiconductor wafer scribes and scribing methods would be useful and advantageous in the arts. Such scribes and methods would provide increased readability for front side scribes useful for wafer tracking during processing while mitigating contamination and reducing cost. SUMMARY OF THE INVENTION [0007] In carrying out the principles of the present invention, in accordance with an embodiment thereof, a method for manufacturing a semiconductor wafer having a front side laser scribe includes forming a scribe foundation on the front surface of the semiconductor wafer and laser scribing the scribe foundation. [0008] According to one aspect of the invention, the method for manufacturing a semiconductor wafer has scribe foundation forming steps including depositing and etching at least one dielectric layer on the front side of the semiconductor wafer followed by depositing and etching at least one metallic layer on the dielectric layer. According to another step of the invention, the scribe foundation thus formed on the front surface of the semiconductor wafer is laser scribed with a trackable scribe. [0009] According to another aspect of the invention, a step of depositing at least one metallic layer to form a scribe foundation on the front side of a semiconductor wafer is performed in combination with a step of forming a top level metal layer on the semiconductor wafer, [0010] According to another aspect of the invention, an exemplary embodiment includes a semiconductor wafer having a front side laser scribe on a scribe foundation. The scribe has a plurality of scribe marks less than approximately 2 micrometers in depth. [0011] According to yet another aspect of the invention, an example is described in which the front side laser scribe includes a number of scribe marks approximately 50 micrometers to approximately 100 micrometers in diameter. [0012] The invention provides technical advantages including but not limited to providing a semiconductor wafer with a trackable front side scribe with increased readability. Further technical advantages include cost savings, compatibility with semiconductor wafer processing techniques and equipment, and reduced risk of contamination of the semiconductor wafer during processing. These and other features, advantages, and benefits of the present invention will become apparent to one of ordinary skill in the art upon careful consideration of the detailed description of representative embodiments of the invention in connection with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS [0013] The present invention will be more clearly understood from consideration of the following detailed description and drawings in which: [0014] FIG. 1A is a top view of an example of a preferred embodiment of a front side laser wafer scribe according to the invention; [0015] FIG. 1B is a close-up partial top view of the example of a preferred embodiment of a front side laser wafer scribe of FIG. 1A; [0016] FIGS. 2A through 2D illustrate examples of steps in scribing a semiconductor wafer according to a preferred embodiment of the invention; [0017] FIG. 2A depicts a partial cross section view of an example of a semiconductor wafer with a passivation layer applied; [0018] FIG. 2B illustrates a partial cross section view of an example of a semiconductor wafer with an etched passivation layer; [0019] FIG. 2C shows a partial cross section view of an example of a semiconductor wafer with a metal layer applied to the etched passivation layer; [0020] FIG. 2D is a partial cross section view of an example of a semiconductor wafer with an etched metallic layer on an etched passivation layer to form a scribe foundation; Continue reading... Full patent description for Laser scribe on front side of a semiconductor wafer Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Laser scribe on front side of a semiconductor wafer patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Laser scribe on front side of a semiconductor wafer or other areas of interest. ### Previous Patent Application: Method of fabricating semiconductor device Next Patent Application: Method of fabricating semiconductor device Industry Class: Semiconductor device manufacturing: process ### FreshPatents.com Support Thank you for viewing the Laser scribe on front side of a semiconductor wafer patent info. 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