Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – For cleaning a specific substrate or removing a specific...
Reexamination Certificate
1998-06-16
2001-11-20
Gupta, Yogendra N. (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
For cleaning a specific substrate or removing a specific...
C510S176000, C510S178000, C510S197000, C510S200000, C510S201000, C510S202000, C510S212000, C510S254000, C510S407000, C510S499000, C510S500000, C134S001200, C134S001300
Reexamination Certificate
active
06319884
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to stripping compositions to remove polymer coatings from electronic components and, more particularly, to a stripping composition that removes polyimide coatings from semiconductor integrated circuit devices for rework of the device without damaging the underlying metal circuitry of the device. In one particular application, a cured polyimide used as a top seal of an integrated circuit chip module is removed for rework using a method employing the stripping composition of the invention.
2. Description of Related Art
The manufacture of semiconductor integrated circuits typically involves highly complex, time-consuming and costly processes which, with continually narrower line width requirements, must be achieved with an ever increasing degree of precision. During the manufacture of the semiconductor and semiconductor microcircuits, it is necessary to coat the substrates from which the semiconductors and microcircuits are made with a polymeric organic film, generally referred to as a photoresist, e.g., a substance which forms a patterned image upon exposure to light and developing. These type photoresists are used to protect selected areas of the surface of the substrate while a process such as etching is used to selectively modify materials at unprotected areas of the substrate.
In the manufacture of integrated circuits, the process steps include coating onto the surfaces of semiconductor substrates materials such as metals to define the circuitry, dielectrics as insulators and organic polymeric materials to protect the circuit patterns in the electronic component. The substrate is typically an SiO
2
dielectric covered silicon wafer and contains metallic microcircuitry such as aluminum or aluminum alloys in and/or on the dielectric surface.
Basically, the fabrication of integrated circuits utilizes a photoresist composition which generally comprises a polymeric resin, a radiation sensitive compound and a suitable solvent to enable forming a film of the photoresist over a particular substrate for photolithographically delineating patterns on such substrates. In a typical processing scheme, the photoresist compositions are spun on or applied to the substrate using methods known in the art. Then the photoresist compositions are typically subjected to a pre-exposure bake to drive off a portion of the solvent to impart dimensional stability to the film. The coated substrate is selectively exposed with radiation such as UV, e-beam or x-ray spectra through a patterning mask using an appropriate exposure tool for such exposure. After exposure, the coated substrate undergoes a development process where, due to selective dissolution of certain areas, a pattern is formed or developed. In certain areas of the photoresist film, the photoresist material is completely removed whereas in the other areas the remaining photoresist forms a pattern having a desired or intended configuration. Such patterns are used to mask or protect the substrate for subsequent wet or dry etching processes, the deposit of conductor or insulative patterns, or for incorporation of the pattern photoresist into the device or package as, for example, an insulating or dielectric layer.
In one fabrication process for an integrated circuit, a top coating can be applied to the integrated circuit. Typically, a polymer layer is applied to the top surface of the integrated circuit and developed to expose pads on the surface of the integrated circuit device. The polymer is then cured and an interconnect is made through the surface of the integrated circuit device.
Polyimides are increasingly being used in integrated circuit manufacture. The use of a polyimide as a fabrication aid includes application of the polyimide as a photoresist, planarization layer and insulator. In these applications, the polymers are applied to a wafer substrate and subsequently cured in the desired pattern by a suitable method. When the polyimide is used as a seal or a top coat, the polyimide layer is not removed except for the areas over the pads and remains on the surface of the semiconductor device.
Semiconductor devices are very expensive and if there is a defect in the device, it is highly desirable to be able to repair the device. To repair (typically termed “rework”) the device, it is necessary to remove coatings such as polyimides, epoxies and the like and it is essential that the underlying metallization of the device not be adversely affected by the stripping composition.
SUMMARY OF THE INVENTION
Bearing in mind the problems and deficiencies of the prior art, it is therefore an object of the present invention to provide a stripping composition which is effective to remove polyimides, epoxies, hardened photoresists, and other polymer coatings from semiconductor substrates without adversely affecting the metallic circuitry of the device.
It is another object of the present invention to provide a method for removing polyimides, epoxies, hardened photoresists, and other polymers from semiconductor devices using a stripping composition and which method does not adversely affect the metallic circuitry of the device.
A further object of the invention is to provide semiconductor devices which have been reworked by removing polyimides, epoxies, hardened photoresists, or other polymer layers from the semiconductor device.
Other objects and advantages of the present invention will be readily apparent from the following description.
The above and other objects and advantages, which will be apparent to one of skill in the art, are achieved in the present invention which is directed, in a first aspect, to a non-aqueous cleaning composition capable of removing cured polyimides, epoxies, hardened photoresists, and other polymers, e.g., in the form of photoresists, top seals, top coatings, etc., from a metal containing substrate such as a semiconductor device without any significant adverse effect, e.g., corrosion, on the metal the composition consisting essentially of less than 50% by weight of a solvent such as N-methyl-2-pyrrolidone (NMP) and at least one alkanolamine defined by the following formula:
H
3−n
N((CH
2
)
m
(CHOH)(R))
n
wherein m is 1 or 2;
R is H or C
1
-C
3
alkyl; and
n is 1, 2 or 3.
The preferred alkanolamines are the monoethanolamines specifically monoethanolamine, and diethanolamine wherein m is 1, R is H and n is 1 or 2. In a highly preferred embodiment, the solvent such as NMP is less than 10%, by weight. In a further highly preferred embodiment, the non-aqueous cleaning composition consists essentially of monoethanolamine.
For some stripping applications it is preferred to use a mixture of alkanolamines, e.g., monoethanolamine and diethanolamine, and the non-aqueous cleaning composition consists essentially of, by weight, about 50 to 100% monoethanolamine and 0 to 50% diethanolamine, preferably 90 to 100% monoethanolamine and 0 to 10% diethanolamine.
In another aspect of the invention, a method is provided for removing polyimide, cured polyimide, epoxy, photoresist, hardened photoresist, or other polymers from substrates such as semiconductor devices comprising the steps of:
providing a substrate such as a semiconductor device having a polyimide or other polymer as part of the device;
contacting the substrate for an effective time with a non-aqueous cleaning composition at an elevated temperature, the non-aqueous cleaning composition consisting essentially of less than 50% by weight of a solvent such as NMP and at least one alkanolamine having the formula:
H
3−n
N((CH
2
)
m
(CHOH)(R))
n
wherein m is 1 or 2;
R is H or C
1
-C
3
alkyl; and
n is 1, 2 or 3.
The temperature of the cleaning solution may vary widely with higher temperatures generally providing faster removal rates. A cleaning composition temperature of above room temperature, e.g., 35° C. to 170° C., preferably 75 to 135° C. is preferred for a removal rate of less than about 1-3 hours.
In another aspect of the invention, it is preferred to use a cleaning composition at a tem
Leduc Marilyn R.
Linde Harold G.
Viens Gary P.
Boyer Charles
Gupta Yogendra N.
International Business Machines - Corporation
Walter, Jr. Howard J.
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