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Micro Mushroom-Flange Pin Joints and Method for their Fabrication

IP.com Disclosure Number: IPCOM000113728D
Original Publication Date: 1994-Sep-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 44K

Publishing Venue

IBM

Related People

Fan, L: AUTHOR [+2]

Abstract

Disclosed is a micro pin-joint structure with mushroom flange and the method of their fabrication. Integrated structures to constrain movements are essential for micromechanisms, and the key component for large rotational movement is a pin joint structure [*]. To overcome the thickness limits of a few micrometers as in Fig. 1(a) for a polysilicon microstructure, we use a new pin-joint microstructure constrained by mushroom flanges, and with plated metal as the structure material. The rotor and axle structure can be tens-of-micrometers thick. Fig. 1(b) shows the cross section and indicates the process to integrate such a pin-joint structure.

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Micro Mushroom-Flange Pin Joints and Method for their Fabrication

      Disclosed is a micro pin-joint structure with mushroom flange
and the method of their fabrication.  Integrated structures to
constrain movements are essential for micromechanisms, and the key
component for large rotational movement is a pin joint structure [*].
To overcome the thickness limits of a few micrometers as in Fig. 1(a)
for a polysilicon microstructure, we use a new pin-joint
microstructure constrained by mushroom flanges, and with plated metal
as the structure material.  The rotor and axle structure can be
tens-of-micrometers thick.  Fig. 1(b) shows the cross section and
indicates the process to integrate such a pin-joint structure.

First, a seed layer/ sacrificial layer/seed layer sandwich is
deposited (buried seed-layer process).  A resist stencil is then
defined and the rotor metal is plated.  After removing the
photoresist and the second seed layer, a second sacrificial layer is
deposited and the anchoring area is patterned and etched to the first
seed layer.  After removing the photoresist, no further lithography
is necessary.  A plating is performed until the mushroom forms as a
flange to constrain the rotor.  In the final step, the sacrificial
layers are removed and a free rotatable element is formed.  In this
process, only two masks are necessary and greatly extend the feasible
thickness of the structures because of the nature of stencil plating
as compared to etching int...