Active solid-state devices (e.g. – transistors – solid-state diode – Physical configuration of semiconductor
Reexamination Certificate
1998-08-20
2001-04-10
Saadat, Mahshid (Department: 2815)
Active solid-state devices (e.g., transistors, solid-state diode
Physical configuration of semiconductor
C257S620000, C438S460000, C438S462000
Reexamination Certificate
active
06215172
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates generally to the manufacturing of integrated circuits and in particular the present invention relates to a grinding technique for preparing integrated circuit dies for further assembly process steps.
BACKGROUND OF THE INVENTION
Fabrication of integrated circuit assemblies involves a complicated process including many steps. Depending on the desired product, the steps may vary from manufacturer to manufacturer and vary for different types of circuits. The basic process includes producing an ingot of a substrate material such as silicon having a highly crystalline structure. The ingot is cut into a number of thin wafers which are further ground and polished producing smooth and flat surfaces and smooth edges preferably free from defects such as notches, chips or other surface flaws.
Each wafer is then subjected to a number of intricate process steps to form a plurality of the integrated circuit patterns on one side defining an active circuitry surface. Each wafer is divided or cut into a large number of circuit dies which will eventually be added to integrated circuit assemblies during further process steps. Each die is precisely cut from the wafer to leave a layer of substrate material or scribe on the edges of the dies. Individual dies may be back ground to remove some of the substrate from the inactive surface. The scribe material is left on the edges to protect the active circuitry from damage during further processing steps and to prevent short circuits between the die and another active circuit or lead.
Today's rapidly advancing technology is producing a need for ever smaller and more densely packed circuits and circuitry. The smaller circuits make producing functional and flawless circuits more difficult. There is a continuing need to improve the process to provide a flawless, high quality integrated circuit having more active circuits and to do so in a smaller package.
For the reasons stated above, and for other reasons stated below, which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for an improved process of manufacturing integrated circuits which are smaller in size and more reliable than conventionally manufactured components.
SUMMARY OF THE INVENTION
The above-mentioned problems with present wafer manufacturing technology and other problems are addressed by the present invention and which will be understood by reading and studying the following specification. A method of producing an integrated circuit die of improved reliability, durability and dimensional characteristics is described which is useful in the process of fabricating integrated circuit assemblies and the like.
In particular, one method of the invention adds an additional step to the conventional manufacturing process for integrated circuits. A die which has been cut from a wafer is further ground, polished or otherwise treated to remove a portion of the remaining substrate or scribe layer on at least a portion of the edge of the die. Another method of the invention includes further grinding or polishing the entire perimeter edge of a particular die to remove a portion of the remaining scribe layer thereon. Another method of the invention includes the additional step of grinding or polishing a bi-level edge on at least a portion of the perimeter edge of a die. The bi-level edge may be produced in one of two ways. Some of the remaining scribe material may be removed from part of the die's perimeter edge to produce the bi-level edge. Alternatively, the entire edge may be partly ground or polished and then further grinding or polishing a portion of the scribe to produce the bi-level edge. This method creates a bi-level or stepped edge on the die. Such a bi-level edge may be produced on the entire perimeter edge or just a portion of the perimeter edge.
The methods disclosed produce an integrated circuit die which is slightly smaller in length and width than a conventionally produced die. The method further produces a die which is less susceptible to damage such as edge chipping or die cracking. A chip in the edge of a die produces a weak point in its edge which may cause the die to crack during further processing or assembly steps. Such a flaw or chip may also cause a short or otherwise damage the active circuitry of the die.
The invention may be utilized to produce a slightly smaller die having the same circuit capacity as a die which has not undergone the process of the invention. A smaller die may be useful in applications where one previously would have been too large taking up too much space within an integrated circuit assembly. Alternatively, the invention may be used to produce a die having increased circuit capacity with no size increase. In particular, some electronic packages require integrated circuit assemblies of a particular maximum size including the plastic encapsulation material. A die which has had most of the remaining scribe removed from the edges saves length and width permitting a die having more circuit capacity to be used within an application without increasing the size of the assembly.
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Micro)n Technology, Inc.
Saadat Mahshid
Schwegman Lundberg Woessner & Kluth P.A.
Wilson Allan R.
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