Semiconductor device manufacturing: process – Coating with electrically or thermally conductive material – To form ohmic contact to semiconductive material
Reexamination Certificate
2001-12-06
2004-05-04
Zarabian, Amir (Department: 2822)
Semiconductor device manufacturing: process
Coating with electrically or thermally conductive material
To form ohmic contact to semiconductive material
C438S118000
Reexamination Certificate
active
06730595
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a protecting method for a semiconductor wafer and a surface protecting adhesive film for a semiconductor waver used in said method. More specifically, it relates to a protecting method for a semiconductor wafer which is useful to prevent breakage of a semiconductor wafer in a step of thinning a semiconductor wafer and which can improve productivity, and a surface protecting adhesive film for a semiconductor wafer used in said method.
BACKGROUND OF THE INVENTION
A step of processing a semiconductor wafer comprises a step of adhering a surface protecting adhesive film for a semiconductor wafer to a circuit-formed surface of the semiconductor wafer, a step of processing a non-circuit-formed surface of the semiconductor wafer, a step of peeling the surface protecting adhesive film for the semiconductor wafer, a dicing step of dividing and cutting the semiconductor wafer, a die bonding step of bonding the divided semiconductor chip to a lead frame, then a molding step of sealing the semiconductor chip with a resin for protecting the outer portion, and the like.
In the die bonding step, a method in which a resin paste as a die bonding material is supplied to a lead frame and a semiconductor chip is put thereon for bonding has been so far mostly used. However, when the resin paste is used, it is hard to uniformly coat the same on the lead frame. Accordingly, there are problems that voids are generated in curing the bonding layer, chip crack is generated, and so forth.
For improving a non-uniform coating property which is a defect of the resin paste as the die bonding material and rationalizing the overall step, Japanese Patent Laid-Open No. 302,629/1994 discloses a method in which a bonding film for die bonding is used in a die bonding step. This method is a method in which after a step of adhering a bonding film for die bonding to a non-circuit-formed surface of a semiconductor wafer, a die bonding step of adhering the semiconductor wafer to which the bonding film for die bonding is fixed on a dicing tape and dividing and cutting the same and a step of peeling the dicing tape, a step of die-bonding the semiconductor chip to a lead frame is performed.
This method is a method in which prior to conducing the dicing step, the bonding film for die bonding is heat-adhered to the non-circuit-formed surface of the semiconductor wafer having a thickness of approximately 300 &mgr;m at 150 to 180° C. using a roll, the semiconductor wafer with the bonding agent adhered is stuck to a dicing tape and divided and cut into the semiconductor chip with the bonding agent, and the semiconductor chip with the bonding agent adhered is then peeled from the dicing tape and hot-pressed on the lead frame. This method, however, involves serious problems that when the non-circuit-formed surface of the semiconductor wafer is processed to further thin the semiconductor wafer, especially to less than 200 &mgr;m, the semiconductor wafer is broken with a pressure of a roll in adhering the bonding film for die bonding unless a surface protecting adhesive film for a semiconductor wafer is adhered, and so forth.
In recent years, thinning of a semiconductor chip has been in high demand, and a chip having a thickness of 30 to 100 &mgr;m has been required. Consequently, a protecting method for a semiconductor wafer by which a bonding film for die bonding can be adhered without breaking even the thus-thinned semiconductor wafer has been in demand.
Disclosure of the Invention
This invention aims to provide, in view of the foregoing problems, a protecting method for a semiconductor wafer which can prevent breakage of a semiconductor wafer even when a semiconductor wafer is thinned to a thickness of 200 &mgr;m or less, and a surface protecting adhesive film for a semiconductor wafer used in the protecting method.
The present inventors have assiduously conducted investigations, and have consequently found that the foregoing problems can be solved such that in performing a series of steps of adhering a surface protecting adhesive film for a semiconductor wafer to a circuit-formed surface of the semiconductor wafer, processing a non-circuit-formed surface of the semiconductor wafer and then adhering a bonding film for die bonding to the non-circuit-formed surface of the semiconductor wafer, the bonding film for die bonding is adhered to the non-circuit-formed surface of the semiconductor wafer in a state where the surface protecting adhesive film for the semiconductor wafer is adhered to the circuit-formed surface of the semiconductor wafer and a surface protecting adhesive film for a semiconductor wafer in which an adhesive layer is formed on one surface of a substrate film at least one layer of which is made of a resin having a melting point of 200° C. or more is used. This finding has led to the completion of the invention.
That is, the first aspect of this invention is a protecting method for a semiconductor wafer comprising a first step of adhering a surface protecting adhesive film for a semiconductor wafer to a circuit-formed surface of the semiconductor wafer, a second step of processing a non-circuit-formed surface of the semiconductor wafer and a third step of adhering a bonding film for die bonding to the non-circuit-formed surface of the semiconductor wafer, characterized in that the third step is performed without peeling the surface protecting adhesive film for the semiconductor wafer and a surface protecting adhesive film for a semiconductor wafer in which an adhesive layer having a storage elastic modulus at 150° C. of at least 1×10
5
Pa and a thickness of 3 to 100 &mgr;m is formed on one surface of a substrate film at least one layer of which is made of a resin having a melting point of 200° C. or more is used.
The characteristic features of the first aspect of this invention are that in a series of the steps from the adhesion of the surface protecting adhesive film for the semiconductor wafer to the circuit-formed surface of the semiconductor wafer to the peeling thereof, the step of adhering the bonding film for die bonding to the non-circuit-formed surface of the semiconductor wafer is performed subsequently to the step of processing the non-circuit-formed surface of the semiconductor wafer in a state where the surface protecting adhesive film for the semiconductor wafer is adhered to the circuit-formed surface of the semiconductor wafer, and that the adhesive film in which the adhesive layer is formed on one surface of the substrate film at least one layer of which is made of the resin having the melting point of 200° C. or more is used as the surface protecting adhesive film for the semiconductor wafer used in these steps.
Further, the second aspect of this invention is a surface protecting adhesive film for a semiconductor wafer used in the protecting method for the semiconductor wafer according to the first aspect, and it is a surface protecting adhesive film for a semiconductor wafer suitably used to produce a thin semiconductor wafer, in which an adhesive layer having a storage elastic modulus at 150° C. of at least 1×10
5
Pa and a thickness of 3 to 100 &mgr;m is formed on one surface of a substrate film at least one layer of which is made of a resin having a melting point of 200° C. or more and which has a thickness of 50 to 350 &mgr;m.
According to this invention, breakage, contamination and the like of the semiconductor wafer in the foregoing series of the steps can be prevented even in a thin semiconductor wafer having a thickness of 200 &mgr;m or less.
Best Mode for Carrying Out the Invention
This invention is described in detail below. In a method of producing a semiconductor wafer to which the protecting method for the semiconductor wafer according to this invention is applied, as described above, the first step of adhering the surface protecting adhesive film for the semiconductor wafer to the circuit-formed surface (hereinafter referred to as a surface) of the semiconductor wafer and the second step of processing the non-circuit-f
Fujii Yasuhisa
Fukumoto Hideki
Hirai Kentaro
Kataoka Makoto
Koshimizu Takanobu
Burns Doane , Swecker, Mathis LLP
Mitsui Chemicals Inc.
Perkins Pamela
Zarabian Amir
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