Electrolysis: processes – compositions used therein – and methods – Product produced by electrolysis involving electrolytic...
Reexamination Certificate
1999-07-09
2001-09-04
Bell, Bruce F. (Department: 1741)
Electrolysis: processes, compositions used therein, and methods
Product produced by electrolysis involving electrolytic...
C205S078000
Reexamination Certificate
active
06284120
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of electroplating capable of forming a column-shaped electrodeposit structure by using a photoresist over a seed layer, such as a conductive metal layer.
2. Description of the Prior Art
Electrodeposition or electroplating is one of the key technologies in the field of micromachining. A method of electroplating comprises a step of supplying electric current to a seed layer of conductive metal material in an electrolytic solution, so as to allow an electrodeposit to grow over the seed layer. When a predetermined pattern is defined on the seed layer by using a photoresist layer, for example, before the supply of electric current, an electrodeposit structure is allowed to grow over the seed layer at the exposed surface surrounded by the photoresist layer. The electrodeposit structure can be shaped into the predetermined pattern.
For example, when a column-shaped electrodeposit structure is intentionally formed by electroplating, a photoresist layer serves to define a column-shaped space by its wall surfaces upright to the seed layer. However, the column-shaped space hardly allows the electrolytic solution to enter the space, so that a bubble or bubbles tends to remain in the space. In addition, gas such as hydrogen generated in the electrolytic solution during supply of electric current cannot smoothly get out of the column-shaped space, either. Accordingly, the electrodeposit structure sometimes cannot grow enough over the seed layer within the column-shaped space because of interruption of the bubbles.
SUMMARY OF THE INVENTION
It is accordingly an object of the present invention to provide a method of electroplating capable of allowing bubbles to smoothly get out of a column space surrounded by a photoresist layer.
According to the present invention, there is provided a method of electroplating, using a photoresist layer on a seed layer so as to form: a wall surface surrounding a column space standing on the seed layer; and at least a ridge on the wall surface extending from the seed layer toward an opening of the column space.
It has been confirmed that such a ridge serves to allow the electrolytic solution to be smoothly introduced into the column space, so that bubbles in the column space can be easily driven out of the column space during the method of electroplating. An electrodeposit structure reliably grows within the column space all over the exposed surface of the conductive seed layer. The electrodeposit structure can be reliably shaped into a full column shape without any cavity or crack.
In this case, the electrodeposit structure may comprise a column body standing on the conductive seed layer, and at least a stripe of recession formed on a peripheral surface of the column body so as to extend from the conductive seed layer to the upper end of the peripheral surface. The conductive layer may be made from metal material.
The ridge may include an edge extending from the conductive seed layer to the opening of the column space. The edge serves to reduce the contact area between the ridge and bubble, so that the bubble can be easily driven out of the column space. The edge may be a ridge of an obtuse angle or a ridge of an acute angle. An electrodeposit structure obtained through this method of electroplating may have the recession in the form of a notch.
The column space may be faced by ridges from four directions. Such disposition of the ridges may serve to form a column-shaped electrodeposit structure surrounded by four surface areas of the peripheral surface, for example. The obtained electrodeposit structure may have four recessions in respective surface areas of the column body.
In addition, if the wall surface and ridge at the photoresist layer extend in the direction vertical to the surface of the conductive seed layer, the column-shaped electrodeposit structure may be obtained to stand upright to the conductive seed layer. The obtained electrodeposit structure may have the peripheral surface and recession upright to the surface of the conductive seed layer.
In particular, the column space of the aspect ratio greater than 1 hardly allows the electrolytic solution to be introduced into the space so as to drive bubbles out of the space. The method of electroplating according to the present invention may be most useful in this situation. Here, the aspect ratio represents the ratio of H/d where H is the height of the column space and d is the width of the wall surface. The obtained electrodeposit structure may have a column-shaped body of the aspect ratio greater than 1.
The aforementioned method of electroplating may be used to manufacture a head slider for a disk drive unit, comprising a medium-opposing surface opposed to a surface of a recording medium, for example, and a column terminal standing on the medium-opposing surface. The head slider may be employed in a recording disk drive such as a magnetic recording disk drive. When the terminals are formed according to the aforementioned method of electroplating, at least a stripe of recession is formed on a peripheral surface of the column terminal so as to extend from the medium-opposing surface toward an upper end of the peripheral surface.
REFERENCES:
patent: 5403680 (1995-04-01), Otagawa et al.
patent: 5815347 (1998-09-01), Pattanaik
patent: 5843537 (1998-12-01), Kim et al.
patent: 5936813 (1999-08-01), Kim et al.
patent: 6105238 (2000-08-01), Chestnut et al.
patent: 8124445 (1996-05-01), None
patent: 9081924 (1997-03-01), None
Imamura Takahiro
Katayama Masaki
Bell Bruce F.
Fujitsu Limited
Greer Burns & Crain Ltd.
Smith-Hicks Erica
LandOfFree
Method of electroplating and electrodeposit structure does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of electroplating and electrodeposit structure, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of electroplating and electrodeposit structure will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2505247