Semiconductor device manufacturing: process – Packaging or treatment of packaged semiconductor
Reexamination Certificate
1999-09-20
2001-09-04
Tsai, Jey (Department: 2812)
Semiconductor device manufacturing: process
Packaging or treatment of packaged semiconductor
C438S108000, C438S119000
Reexamination Certificate
active
06284564
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to methods for fabrication of High Density Interconnect (HDI) circuits, and more particularly to such methods which reduce the number of processing steps.
BACKGROUND OF THE INVENTION
HDI circuits are formed by mounting two or more semiconductor chips so that those surfaces having electrodes are coplanar, and then applying a layer of visually transparent, ultraviolet absorbent dielectric material, generally polyimide, over the electrode or bonding pad sides of the juxtaposed semiconductor chips. A laser is optically aligned to the position of each chip through the transparent dielectric, and an ultraviolet laser beam is used to make holes through the dielectric material at the locations of the electrodes of the semiconductor chips.
Improved HDI manufacturing is desired.
SUMMARY OF THE INVENTION
After the holes are made in the dielectric material in a prior-art method for fabricating HDI structures, and the holes are converted into conductive vias by addition of metallization, a further step is required, which is the step of adding individualized interconnection traces between the set of through vias of each semiconductor chip, whatever orientation they may have, to the standardized interconnection pattern. This task is accomplished by providing an “adaptive” region on the dielectric material around each semiconductor chip, in which the individualized traces are added to connect the various through vias to the standardized interconnection pattern. According to an aspect of the invention, in order to reduce the number of laser alignments required to make the holes through the dielectric interconnection film and to thereby reduce the cost of manufacture, apertures are pre-formed in the dielectric film, using direct writing by a laser or a laser and a mask, at the locations which the electrodes to be interconnected would be if the semiconductor chip mountings were perfect. These holes can be made by illuminating the dielectric film through the apertures of a direct or projection mask which extends over the entirety of the HDI film surface. If the laser beam subtends the entire mask, then no more is needed than to make the apertures. If the laser beam does not subtend the mask, then it may be scanned or stepped over the surface of the mask, so as to form apertures in the underlying dielectric film at the locations of the transparent regions or holes in the mask. As an alternative to the use of a mask, direct laser writing may be used to make the apertures.
After the holes are made in the dielectric film, the semiconductor chips are mounted to a first side or obverse side of the film, with their various electrodes over the holes. This procedure may use “pick-and-place” robotics, while observing the obverse of the film, for placing the chips over the holes. This placement may be further aided by a further optical alignment apparatus, observing the reverse side of the film, for aligning the electrodes visible through the holes in the film, to perform the final alignment. The semiconductor chips may be held in place by any means, including a layer of uncured adhesive material applied to the obverse side of the film, and perforated together with the film material itself. At this point in the fabrication, the chips are perfectly aligned with the through vias, which are perfectly aligned with the mask representing perfect alignment. If the mounting of the semiconductor chips to the dielectric film was performed by using uncured adhesive, the adhesive may now be cured. The interconnection pattern can be applied to the through vias by way of a further mask which matches with the perfectly aligned vias, thereby eliminating the need for the adaptive region. The remaining steps of the HDI processing are conventional.
More particularly, a method according to an aspect of the invention, for interconnecting electrical contacts of semiconductor chips in an HDI context, includes the step applying laser energy to produce apertures or through holes in a dielectric film in a pattern corresponding to the ideal locations of electrodes or terminals of semiconductor chips properly placed on the dielectric film. In one embodiment, this step may include the step of procuring an optical mask defining an ideal pattern of electrodes of semiconductor chips properly aligned in an HDI structure. This mask may be sufficiently large to cover a plurality of HDI circuits being made on a substrate, or it may cover only one such HDI circuit. Laser energy is applied to a dielectric film through apertures or transparent regions of the mask, to thereby make the ideal pattern of holes in the film. Semiconductor chips are mounted to a first side of the dielectric film, with the electrodes in registry with the holes. This has the effect of mounting the semiconductor chips in their ideal locations. The mounting of the semiconductor chips may be accomplished by application of uncured adhesive to the first side of the film before the making of the apertures in the film. The adhesive is then cured, without allowing the holes to close. Electrically conductive material, such as metallization, is applied to a second side of the film and to at least the sides of the holes, so as to interconnect the electrodes with an interconnect pattern of the electrically conductive material.
REFERENCES:
patent: 5125153 (1992-06-01), Frey et al.
patent: 5302547 (1994-04-01), Wojnarowski et al.
patent: 5306670 (1994-04-01), Mowatt et al.
patent: 5468681 (1995-11-01), Pasch
patent: 5590462 (1997-01-01), Hundt et al.
patent: 5932118 (1999-08-01), Yamamoto et al.
patent: 6221693 (2001-04-01), Ho
Balch Ernest Wayne
Douglas Leonard Richard
Gorczyca Thomas Bert
Jones Josetta I.
Lockheed Martin Corp.
Meise W. H.
Tsai Jey
Weinstein S. D.
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