Stock material or miscellaneous articles – Structurally defined web or sheet – Discontinuous or differential coating – impregnation or bond
Reexamination Certificate
2002-09-19
2004-06-01
Jones, Deborah (Department: 1775)
Stock material or miscellaneous articles
Structurally defined web or sheet
Discontinuous or differential coating, impregnation or bond
C428S201000, C428S457000, C428S689000, C428S901000
Reexamination Certificate
active
06743499
ABSTRACT:
This application claims priority to Japanese Patent Application Nos. 2001-287082 filed on Sep. 20, 2001 and 2002-270563 filed on Sep. 17, 2002.
BACKGROUND ART
The present invention relates to a metal filling method and member with filled metal sections in which a metal is filled into fine holes formed in a member, such as through holes or non-through holes formed in a circuit substrate.
For example, in the case of forming through hole electrodes (via hole electrodes) in a substrate (such as a silicon substrate) in the production process of an IC chip and so forth, a plating method is typically used in which through holes for the through hole electrodes are opened in the substrate, the substrate is inserted into a plating solution (molten metal) in which a conductive metal has been solved, and immersed in that the plating solution to fill the into the conductive metal through holes.
However, in the case of filling metal into through holes by the plating method, there are cases in which, for some reason, the plating layer concentrically grow near the through hole entrance of the substrate, thereby making it difficult for plating liquid to enter to the back of the through holes. In this case, there are problems such as the occurrence of roughness within the through holes that made it difficult to fill metal in a state free of voids.
In cases in which the through holes are fine holes having a high aspect ratio (depth of the hole/opening diameter of the hole) in particular, since it is difficult for the plating solution to penetrate to the back of the through holes, concentrated growth of the plating layer near the through hole entrance of the substrate occurs easily, causing the problems described above to become remarkable. For example, in the case of high-density, three-dimensional mounting consisting of the stacking of silicon IC chips and so forth, although there are cases in which through electrodes (through wirings) are formed in the substrate for connecting the wiring patterns on the top and bottom of a substrate, since the through holes for through electrodes opened in the substrate are fine holes having a high aspect ratio, if through electrodes are attempted to be formed by filling metal into the through holes using the plating method described above, it is difficult to reliably form through electrodes that are free of voids.
SUMMARY OF THE INVENTION
In consideration of the above problems, the object of the present invention is to provide a metal filling method and member with filled metal sections that allows filling of a plating solution to be carried out reliably particularly near openings that open on the outer surface of a work piece of fine holes formed in that work piece.
The metal filling method according to the present invention is a method for filling metal into fine holes formed in a work piece, and is characterized by forming a metal layer on the inner surface of an end of each fine hole that opens in an outer surface of the work piece, followed by immersing the work piece in the plating solution, filling the plating solution into the fine holes, removing the work piece from the plating solution with one of ends along an axial direction of each fine hole still occluded, and then cooling the work piece.
In this metal filling method, a constitution can also be employed in which the fine holes are through holes that pass through the work piece, the metal layer is formed on the inner surface of at least one end of both ends in the axial direction of each through hole, and when the work piece, which has been immersed in the plating solution to fill the plating solution into the through holes, is removed from the plating solution, an opening in the other end of the axial direction of each through holes is occluded with a sealing material as the above one of ends along the axial direction of each fine hole. Moreover, the metal layer can be formed on the inner surface of the end of the fine hole that opens in the outer surface of the work piece as well as on the outer surface of the work piece extending around the end of the fine hole on which the metal layer is formed. In this case, after immersing this work piece in the plating solution within a plating solution bath to fill the plating solution into the fine hole but prior to cooling of the work piece, the plating solution filled into the fine hole is padded at the sites where the metal layer was formed on the inner surface of the end of the fine hole that opens on the outer surface of the work piece and on the outer surface of the work piece extending around the end of the fine hole on the work piece which is removed from the plating solution. And then, a filled metal section formed by solidification of the plating solution within the fine holes, and an external metal section formed by solidification of the padded sections of the plating solution, are formed unitarily by cooling said work piece.
In addition, in the metal filling method as claimed in the present invention, the metal layer around the openings of fine holes in the outer surface of a work piece can also be patterned corresponding to the shape of the external metal sections to be formed prior to immersing the work piece in the plating solution.
The member with filled metal sections according to the present invention is a member with filled metal sections having filled metal sections formed by filling a metal into fine holes formed in a work piece, and is characterized by a metal layer being formed on the inner surface of an end of the above fine holes that opens to the outer surface of the work piece, and the filled metal sections being filled at a site that includes the end of the fine holes on which the above metal layer is formed. A constitution can also be employed for this member with filled metal sections in which a metal layer is formed not only on the inner surface of the end of the fine holes that opens in the outer surface of the work piece, but also on the outer surface of the work piece that extends around the end of the fine holes on which the metal layer is formed, and external metal sections, which are unitarily formed with the filled metal sections, and padded so as to protrude from the outer surface of the work piece, are formed so as to cover the metal layer.
The work piece as claimed in this invention is a member having fine holes for metal filling that are either through holes (fine holes) or non-through holes (fine holes in which only one end in the axial direction open on the outer surface of the work piece, while the other end are not open), examples of which include a substrate (circuit substrate) in which via holes or so-called inner via holes are formed. In addition to semiconductor materials such as silicon or gallium arsenide (GaAs), various other materials such as glass or other insulating material can be used for the material of the work piece.
Examples of methods for forming fine holes (through holes or non-through holes) in the work piece as claimed in the present invention include Deep-Reactive Etching (DRIE) as is represented by Inductively Coupled Plasma-Reactive Ion Etching (ICP-RIE), wet etching methods using an etching solution, mechanical processing methods using a microdrill, and optical excitation electrolytic polishing. Fine hole diameter, work piece dimensions, fine hole depth and so forth are suitably set according to the application and so forth, and the cross-sectional shape of the fine holes (shape of the cross-section perpendicular to the axial direction) may be of any shape such as circular, oval, triangular or rectangular (including a square).
In the metal filling method as claimed in the present invention, a technique is employed in which, after immersing a work piece in a plating solution which is composed of heated and melted conductive metal and filling this plating solution into the fine holes by allowing a plating solution to flow into the fine holes, the work piece is removed from the plating solution with one of the ends in the axial direction of the above fine holes still occluded, after whic
Suemasu Tatsuo
Takizawa Takashi
Fujikura Ltd.
Hoffmann & Baron , LLP
Jones Deborah
Xu Ling
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