Semiconductor device manufacturing: process – Packaging or treatment of packaged semiconductor – Making plural separate devices
Reexamination Certificate
2000-06-20
2001-08-14
Graybill, David E. (Department: 2814)
Semiconductor device manufacturing: process
Packaging or treatment of packaged semiconductor
Making plural separate devices
C438S112000, C438S114000, C438S118000, C438S123000, C438S465000
Reexamination Certificate
active
06274406
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor device and a method of manufacturing the same. More particularly, the present invention relates to a technique suitable for a package having an LOC (Lead On Chip) structure of a large-scale integrated circuit.
2. Description of the Related Art
The LOC (Lead On Chip) structure allows a relatively small package to accommodate a large semiconductor chip to realize high-density mounting, and is therefore suitable for, e.g., a 16-bit DRAM (Dynamic Random Access Memory). An example of the semiconductor device having the LOC structure is disclosed in, e.g., Japanese Patent Laid-Open No. 4-291950. In the semiconductor device disclosed in this reference, a band-shaped insulating tape
102
with an adhesive applied to its two surfaces is bonded to an inner lead
101
of a lead frame, as shown in FIG.
11
. On the other hand, a polyimide film
104
serving as an &agr;-ray protective film is bonded on a predetermined region of a semiconductor chip
103
where memory cells and their peripheral circuits are formed. As shown in
FIG. 11
, the upper surface of the polyimide film
104
on the semiconductor chip
103
is bonded and fixed to the inner lead
101
with the insulating tape
102
interposed therebetween, and a bonding pad
105
formed on the semiconductor chip
103
is connected to the inner lead
101
by a bonding wire
106
. In the semiconductor device disclosed in Japanese Patent Laid-Open No. 4-291950, the insulating tape
102
has a comb-like shape to prevent voids.
A method of manufacturing the above semiconductor device will be briefly described with reference to FIG.
12
. The manufacturing process is divided into a preprocess group before cutting a semiconductor wafer into semiconductor chips and a post-process group after cutting. In the first step of the preprocess group, memory cells and their peripheral circuits are formed on a semiconductor wafer, and a plurality of semiconductor chips are formed on the semiconductor wafer (step S
101
).
After the prefuse test of the semiconductor chips (step S
102
), a material film, e.g., a polyimide resin film in this case, serving as an &agr;-ray protective film is applied to the entire surface of each semiconductor chip (step S
103
).
The semiconductor wafer on which the protective film is formed is heated at a predetermined temperature (step S
104
).
A photoresist is applied to the surface of the protective film of each semiconductor chip (step S
105
), and developed and patterned by photolithography to form an etching mask (step S
106
). The protective film is anisotropically etched into a shape conforming to the etching mask, and a plurality of openings are formed in the protective film to expose the surfaces of bonding pads formed on the semiconductor chip under the protective film (step S
107
). The resist mask is removed by ashing using O
2
plasma (step S
108
). Back grinding (step S
109
) and laser repair (step S
110
) are performed, and a full wafer test is performed in the final step of the preprocess group (step S
111
).
Next, in the first step of the post-process group, dicing is performed to cut the semiconductor wafer into the semiconductor chips (step S
112
). The following three processes are performed simultaneously with the operation in step S
112
. An adhesive consisting of a polyimide resin material is applied to the two surfaces of a band-shaped polyimide film as an insulating tape (step S
113
), the insulating tape is bonded to inner leads (step S
114
), and the insulating tape is formed into a predetermined shape (step S
115
).
The inner leads are pressed against the surface of the protective film of each cut semiconductor chip with the insulating tapes interposed therebetween. In this state, the resultant structure is heated to bond and fix the semiconductor chip to the inner leads (step S
116
). Each semiconductor chip is loaded into a furnace and subjected to post-baking (step S
117
: this step can be omitted in some cases). The bonding pad in each opening formed in the protective film is connected to a corresponding inner lead by a bonding wire (step S
118
). Resin molding is performed to cover the entire semiconductor chip (step S
119
), thereby completing a package.
According to the above-described method, since an adhesive having the same properties as the insulating tape is applied to the two surfaces of the insulating tape, the thickness of the entire insulating tape can be adjusted appropriately, so cracks in the sealing resin and semiconductor chip can be prevented. However, this method requires various processes (steps S
113
to S
115
) for bonding the insulating tape to the inner leads, so the number of processes in manufacturing a lead frame increases, and the processes become cumbersome. In addition, the insulating tape is difficult to handle because it tends to be burred upon cutting and attract foreign objects. Furthermore, since the number of components increases, the cost largely increases.
SUMMARY OF THE INVENTION
It is an object of the present invention to easily and reliably realize a semiconductor device having a simple LOC structure without using an insulating tape for bonding a semiconductor chip to inner leads.
According to an aspect of the present invention, there is provided a semiconductor device having a structure in which a semiconductor chip is bonded and fixed to an inner lead of a lead frame while being insulated from the inner lead, and a bonding pad formed on the semiconductor chip is connected to the inner lead by a bonding wire, wherein a thermoplastic resin film is formed on a surface of the semiconductor chip, and an upper surface of the thermoplastic resin film is directly bonded to a lower surface of the inner lead.
Preferably, the thermoplastic resin film is at least one of a thermoplastic polyimide resin film and a thermoplastic polyamide resin film.
Preferably, an opening is formed in the thermoplastic resin film to expose a surface of the bonding pad, and the bonding pad in the opening is connected to the inner lead by the bonding wire.
According to another aspect of the present invention, there is provided a semiconductor device having a structure in which a semiconductor chip is bonded and fixed to an inner lead of a lead frame while being insulated from the inner lead, and a bonding pad formed on the semiconductor chip is connected to the inner lead by a bonding wire, wherein a thermosetting resin film is formed on a surface of the semiconductor chip, and an upper surface of the thermosetting resin film is directly bonded to a lower surface of the inner lead.
Preferably, the thermosetting resin film is at least one of a thermosetting polyimide resin film and a thermosetting polyamide resin film.
Preferably, an opening is formed in the thermosetting resin film to expose a surface of the bonding pad, and the bonding pad in the opening is connected to the inner lead by the bonding wire.
According to still another aspect of the present invention, there is provided a semiconductor device having a structure in which a semiconductor chip is bonded and fixed to an inner lead of a lead frame while being insulated from the inner lead, and a bonding pad formed on the semiconductor chip is connected to the inner lead by a bonding wire, wherein a thermoplastic resin film covering a surface of the semiconductor chip is formed between the semiconductor chip and the inner lead, and the semiconductor chip is bonded to the inner lead using only the thermoplastic resin film.
Preferably, the thermoplastic resin film is at least one of a thermoplastic polyimide resin film and a thermoplastic polyamide resin film.
Preferably, an opening is formed in the thermoplastic resin film to expose a surface of the bonding pad, and the bonding pad in the opening is connected to the inner lead by the bonding wire.
According to still another aspect of the present invention, there is provided a semiconductor device having a structure in which a semiconductor chip is bonded and fixed to an inne
Connolly Bove Lodge & Hutz
Graybill David E.
Nippon Steel Semiconductor Corporation
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