U.S. patent application number 16/421698 was filed with the patent office on 2020-01-02 for thinned and flexible semiconductor elements on three dimensional surfaces.
The applicant listed for this patent is Johnson & Johnson Vision Care, Inc.. Invention is credited to Frederick A. Flitsch A. Flitsch, James Daniel Riall Daniel James Daniel Riall, Daniel B. Otts, Randall B Pugh, Adam Toner.
Application Number | 20200004048 16/421698 |
Document ID | / |
Family ID | 49994573 |
Filed Date | 2020-01-02 |
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United States Patent
Application |
20200004048 |
Kind Code |
A1 |
Pugh; Randall B ; et
al. |
January 2, 2020 |
THINNED AND FLEXIBLE SEMICONDUCTOR ELEMENTS ON THREE DIMENSIONAL
SURFACES
Abstract
Methods to form a device whereon flexible component elements are
attached upon three-dimensional surfaces are described. In some
aspects, the present invention includes incorporating flexible
semiconductor devices onto three-dimensional surfaces with
electrical contacts. In some aspects, the formed device may be
incorporated in an ophthalmic device.
Inventors: |
Pugh; Randall B;
(Jacksonville, FL) ; James Daniel Riall; James Daniel
Riall Daniel; (St. Johns, FL) ; Otts; Daniel B.;
(Pleasanton, CA) ; Toner; Adam; (Jacksonville,
FL) ; Flitsch; Frederick A. Flitsch A.; (New Windsor,
NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Johnson & Johnson Vision Care, Inc. |
Jacksonville |
FL |
US |
|
|
Family ID: |
49994573 |
Appl. No.: |
16/421698 |
Filed: |
May 24, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13946006 |
Jul 19, 2013 |
10310294 |
|
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16421698 |
|
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61674887 |
Jul 24, 2012 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01L 2924/0002 20130101;
B29D 11/00038 20130101; G02C 7/083 20130101; H05K 2201/10568
20130101; G02C 7/04 20130101; H05K 1/0284 20130101; H05K 2201/10583
20130101; H01L 23/04 20130101; B29D 11/00817 20130101; G02C 7/049
20130101; H01L 2924/0002 20130101; H01L 2924/00 20130101 |
International
Class: |
G02C 7/08 20060101
G02C007/08; H05K 1/02 20060101 H05K001/02; B29D 11/00 20060101
B29D011/00; G02C 7/04 20060101 G02C007/04 |
Claims
1. An ophthalmic device comprising: a three-dimensional feature
having a cylindrical shape; electrical contacts formed upon the
three-dimensional surface; an electronic element attached to the
electrical contacts, wherein the electronic element comprises a
thinned flexible semiconductor bent to conform to the
three-dimensional feature along at least a portion of the
cylindrical shape.
2. The ophthalmic device of claim 1, wherein the electronic element
is formed from a rectilinear-shaped material.
3. The ophthalmic device of claim 1, wherein the three-dimensional
feature comprises a variable optic component.
4. The method of claim 1, wherein the semiconductor comprises
crystalline silicon, polycrystalline silicon, or amorphous
silicon.
5. The ophthalmic device of claim 1, wherein the three-dimensional
eature and the electronic element are housed within a media
insert.
6. The ophthalmic device of claim 1, wherein the three-dimensional
feature is formed in a helical shape in three dimensions and
wherein the thinned flexible semiconductor is bent in the third
dimension to take on the helical shape of the substrate.
7. The ophthalmic device of claim 1, wherein cylindrical shape of
the substrate insert has a radius of within about 7 mm and 9
mm.
8. The ophthalmic device of claim 1, wherein the thinned flexible
semiconductor comprises a semiconductor-on-insulator substrate.
9. The ophthalmic device of claim 1, wherein the thinned flexible
semiconductor comprises at least one interconnection feature
configured to shield at least a portion of the thinned flexible
semiconductor from incident light radiation.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This patent application is a continuation of U.S. patent
application Ser. No. 13/946,006 filed Jul. 19, 2013 and entitled
"THINNED AND FLEXIBLE SEMICONDUCTOR ELEMENTS ON THREE DIMENSIONAL
SURFACES" which claims the benefit of U.S. Application Ser. No.
61/674,887, filed on Jul. 24, 2012.
BACKGROUND OF THE INVENTION
1. Field of the Invention
[0002] The present invention describes methods to form a device
that includes flexible semiconductor elements located upon
electrical interconnections. More specifically, the flexible
semiconductor elements may be deformed or bent in order to attach
to three-dimensionally shaped regions. The methods described herein
are useful, for example, in the field of energized ophthalmic
devices.
2. Discussion of the Related Art
[0003] Traditionally an ophthalmic device, such as a contact lens,
an intraocular lens or a punctal plug included a biocompatible
device with a corrective, cosmetic or therapeutic quality. A
contact lens, for example, may provide one or more of vision
correcting functionality, cosmetic enhancement, and therapeutic
effects. Each function is provided by a physical characteristic of
the lens. A design incorporating a refractive quality into a lens
may provide a vision corrective function. A pigment incorporated
into the lens may provide a cosmetic enhancement. An active agent
incorporated into a lens may provide a therapeutic functionality.
Such physical characteristics are accomplished without the lens
entering into an energized state.
[0004] More recently, it has been theorized that active components
may be incorporated into a contact lens. Some components may
include semiconductor devices. Some examples have shown
semiconductor devices embedded in a contact lens placed upon animal
eyes. It has also been described how the active components may be
energized and activated in numerous manners within the lens
structure itself. The topology and size of the space defined by the
lens structure creates a novel and challenging environment for the
definition of various functionality. In many embodiments, it is
important to provide reliable, compact and cost effective means to
incorporate components within an ophthalmic device. In some
embodiments, it may be advantageous to include components that may
be thinned and flexible. As a result, novel methods and form factor
solutions that may allow for the thinning and flexibility of some
components are desired both for improvements in the production of
ophthalmic devices and for the general advancement of incorporating
electronic components on non-flat applications. It is important to
note these improvements may find use in non-ophthalmic applications
as well. It is also desirable that methods be generated to address
ophthalmic and non-ophthalmic requirements as they relate to
electronic components on three-dimensional substrates.
SUMMARY OF THE INVENTION
[0005] The thinned and flexible semiconductor elements in
accordance with the present invention overcomes the disadvantages
associated with the prior art as briefly described above.
[0006] The present invention describes methods and devices that
relate to the utilization of thinned flexible components. In some
exemplary embodiments, the resulting devices may be incorporated
into an energized ophthalmic lens with additional functionality.
For example, thinned flexible components may be included in an
energized ophthalmic lens that comprises a variable optic portion
capable of changing the optical properties of the lens in discrete
manners. Furthermore, the present invention teaches methods of
incorporating thinned and flexible semiconductor devices and
elements into space-defining and/or functional structures. In some
exemplary embodiments, there may be non-semiconductor elements that
might be within the scope of the invention. For example, in some
exemplary embodiments it may be desirable to include a thin
flexible silicon dioxide piece with vias as an element.
[0007] In some exemplary embodiments these structures will have
regions within them that are not planar and therefore have
three-dimensional shape. In these embodiments, the regions may have
deposited metallurgical contacts and electrical routing features
upon the complex surface. The thinned and flexible semiconductors
components may be applied upon the metallurgical contacts,
electrical routing features, and upon the complex surfaces. To
attach the flexible devices, the devices may sometimes need to be
bent or deformed from their normal resting state in order to
conform to the complex surface.
[0008] Many different designs for the space-defining structures and
regions therein may exist depending on the desired characteristics
of the device. The different designs may result in complex
three-dimensional surfaces within the regions that may sometimes
require flexibility of some or all of the device components. For
example, in cylindrical designs modeled to be positioned around an
ophthalmic device component, a flexible surface may be contoured
around at least a portion of a radial path of the ophthalmic device
component. When the flat surface is turned around and upon the
radial path to form a cylindrical shape, an axis of the cylindrical
design may be defined by the perpendicular direction to the radial
path.
[0009] Numerous methods and designs that may be used to position
thinned and flexible semiconductor elements within or on different
three-dimensional surfaces will be apparent to one skilled in the
art from the methods and examples described in this disclosure. In
some aspects of the present invention, the methods and designs may
provide for additional or improved functionality of the device
itself, i.e. design features. In some exemplary embodiments
relating in particular to ophthalmic lenses, a design example, used
to prevent unintended light scattering by the semiconductor
elements and conforming to space requirements of the device,
includes a cylindrical design positioned around a component, for
example, a variable optical component, with its axis pointing in a
direction that a light beam may take when it proceeds through at
least some parts of the ophthalmic device and into the eye. This
may be referred to as the axis of an optical path.
[0010] Additional types of device characteristics may dictate the
surface region where flexible devices may be attached. In some
exemplary embodiments, the surface regions may include designs that
are conical or cone-shaped. The cylindrical design features share
some similarity to cone features; however, they differ in that in a
cone feature the dimension of the top radial path and the bottom
radial path of the bent semiconductor may be different. This is
understood from a review of the characteristics of a simple
truncated cone where one end is smaller in radius than the other.
The thinned semiconductor devices may be bent into a cone; however,
unlike the cylindrical design type feature, the starting shape to
bend a flexible device into a cone is not rectilinear--that is it
does not have straight peripheral sides. Rather it has curved or
curvilinear sides.
[0011] A different type of feature used in an ophthalmic device
that may describe the surface region where flexible components may
be attached may derive from shapes referred to as flaps. Flaps are
regions which can be deployed along the general surface shape of
the ophthalmic device. The flaps may be flat or non-flat. In the
case of non-flat flaps, the surface topology of the flap may vary
in multiple directions; however a typical case would occur with
variation in both a radial direction of the ophthalmic device and
in a direction perpendicularly outwards from the radial direction.
Flexible devices may be deployed upon the surfaces of these flaps
and interconnected in numerous ways including by the use of
interconnects which are formed upon the larger surfaces of the flap
features. In related aspects of the invention, different flap
designs can be used in an ophthalmic device to increase the eye's
oxygen exposure.
[0012] The present disclosure may enable numerous advantages in
various types of devices where flexibility may be advantageous and
space constrains generally exist. One type of device includes
semiconductor devices with integrated circuits built upon and
within them. There may be numerous semiconductor devices including
those made of silicon in its various forms, including crystalline,
polycrystalline and amorphous, along with other semiconductors such
as silicon germanium and gallium arsenide. As well, a complicated
device structure may be formed from substrates where the
semiconductor layer may be significantly thin and fabricated in
manners that place it on top of an insulator layer. Thinned
versions of such semiconductor-on-insulator layers may result in
significantly thin and relatively transparent characteristics where
the nature of light interaction, with either semiconductor bulk or
semiconductor-on-insulator devices, may have additional
significance for device performance. For example in some exemplary
embodiments, additional significance for device performance can
include the ability to configure devices that have utility for
light-interacting signals.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The foregoing and other features and advantages of the
invention will be apparent from the following, more particular
description of preferred embodiments of the invention, as
illustrated in the accompanying drawings.
[0014] FIGS. 1A and 1B illustrate an exemplary three-dimensional
substrate that may be used in some ophthalmic devices.
[0015] FIGS. 2A and 2B illustrate exemplary aspects of thinning for
semiconductor and semiconductor on insulator substrates.
[0016] FIGS. 3A and 3B illustrate an exemplary flap structure
incorporated into an ophthalmic device.
[0017] FIGS. 4A and 4B illustrate exemplary vertical design
features located upon structures of an ophthalmic device.
[0018] FIGS. 5A and 5B illustrate exemplary conical design features
located upon structures of an ophthalmic device.
[0019] FIG. 6 illustrates an exemplary radial trench design feature
located upon structures of an ophthalmic device.
[0020] FIG. 7 illustrates the optic region of an ophthalmic device
with an exemplary implementation of transparent semiconductor
elements.
[0021] FIGS. 8A-8D illustrate an exemplary representation of flap,
vertical, radial, trench, and conical designs static bending
aspects.
[0022] FIGS. 9A-9D illustrate exemplary interconnection aspects for
different design types.
[0023] FIGS. 10A-10C illustrate exemplary circuit and circuit
element reliability and design aspects thereof.
[0024] FIGS. 11A-11C illustrate exemplary circuit interconnect
reliability and design aspects thereof.
[0025] FIGS. 12A-12C illustrate an exemplary helical structure
incorporated into an ophthalmic insert device.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0026] The present invention relates to methods and devices useful
to the utilization of thin and flexible semiconductor devices
located upon three-dimensional surfaces. In the following sections
detailed exemplary descriptions of embodiments of the invention
will be given. The description of both preferred and alternate
embodiments are exemplary embodiments only, and it is understood
that to those skilled in the art that variations, modifications and
alterations may be apparent. It is therefore to be understood that
the exemplary embodiments do not limit the scope of the underlying
invention.
Glossary
[0027] In this description and claims directed to the presented
invention, various terms may be used for which the following
definitions will apply:
[0028] "Cylinder Shape" as used herein and sometimes referred to as
"Cylindrical Shape" refers to a generally flat surface flexible
component contoured around at least a portion of a radial path such
that in a cross section, a circle, circular ellipse or oval can
form at least a portion of a rectilinear cylindrical shape. In some
cylindrical shapes, an axis of the cylindrical design may be
defined by the perpendicular direction to the radial path.
[0029] "Energized" as used herein refers to the state of being able
to supply electrical current to or to have electrical energy stored
within.
[0030] "Energy" as used herein refers to the capacity of a physical
system to do work. Many uses within the present invention may
relate to the capacity being able to perform electrical actions in
doing work.
[0031] "Energy Source" as used herein refers to device or layer,
which is capable of supplying energy or placing a logical or
electrical device in an energized state.
[0032] "Energy Harvesters" as used herein refers to device capable
of extracting energy from the environment and convert it to
electrical energy.
[0033] "Functionalized" as used herein refers to making a layer or
device able to perform a function including for example,
energization, activation, or control.
[0034] "Flap" as used herein refers to a surface region where
flexible components may be attached. In different exemplary
embodiments, flaps may be flat or non-flat. In the case of non-flat
flaps, the surface topology of the flap may vary in multiple
directions; however a typical case would occur where variation
would occur both in a radial direction and in a direction
perpendicularly outwards from the radial direction. Flexible
devices may be deployed upon the surfaces of these flaps and
interconnected in numerous manners including by the use of
interconnects which are formed upon the larger surfaces of the flap
features. For example in various designs of energized ophthalmic
device, flaps may be used to provide for improved oxygen exposure
to the ocular surface on which the ophthalmic device can rest
on.
[0035] "Flexible" as used herein refers to the ability of an item
to be spatially deformed or bent from a state with a first
three-dimensional shape to a state with a second and different
three-dimensional shape, wherein the deformed item does not
macroscopically break during deformation.
[0036] "Lens" as used herein and sometimes referred to as
"Ophthalmic Device" refer to any ophthalmic device that resides in
or on the eye. These devices may provide optical correction or may
be cosmetic. For example, the term lens may refer to a contact
lens, intraocular lens, overlay lens, ocular insert, optical insert
or other similar device through which vision is corrected or
modified, or through which eye physiology is cosmetically enhanced
(e.g. iris color) without impeding vision. In some exemplary
embodiments, the preferred lenses of the invention are energized
generally soft contact lenses made from silicone elastomers or
hydrogels, which include but are not limited to silicone hydrogels,
and fluorohydrogels.
[0037] "Lens Forming Mixture" or "Reactive Mixture" or "RMM"
(reactive monomer mixture) as used herein refer to a monomer or
prepolymer material that may be cured and crosslinked or
crosslinked to form an ophthalmic lens. Various embodiments may
include lens-forming mixtures with one or more additives such as UV
blockers, tints, photoinitiators or catalysts, and other additives
one might desire in an ophthalmic lenses such as, contact or
intraocular lenses.
[0038] "Lens Forming Surface" refers to a surface that is used to
mold a lens. In some exemplary embodiments, any such surface may
have an optical quality surface finish, which indicates that it is
sufficiently smooth and formed so that a lens surface fashioned by
the polymerization of a lens forming material in contact with the
molding surface is optically acceptable. Further, in some exemplary
embodiments, the lens-forming surface may have a geometry that is
necessary to impart to the lens surface the desired optical
characteristics, including, spherical, aspherical and cylinder
power, wave front aberration correction, corneal topography
correction and the like as well as any combinations thereof.
[0039] "Lithium Ion Cell" as used herein refers to an
electrochemical cell where Lithium ions move through the cell to
generate electrical energy. This electrochemical cell, typically
called a battery, may be reenergized or recharged in its typical
forms.
[0040] "Substrate Insert" as used herein refers to a formable or
rigid substrate capable of supporting an energy source within an
ophthalmic lens. In some exemplary embodiments, the substrate
insert also supports one or more components.
[0041] "Mold" as used herein refers to a rigid or semi-rigid object
that may be used to form lenses from uncured formulations. Some
preferred molds include two mold parts forming a front curve mold
part and a back curve mold part.
[0042] "Optical Zone" as used herein refers to an area of an
ophthalmic lens through which a wearer of the ophthalmic lens
sees.
[0043] "Power" as used herein refers to work done or energy
transferred per unit of time.
[0044] "Rechargeable" and also referred to as "Re-energizable" as
used herein refer to a capability of being restored to a state with
higher capacity to do work. Many uses within the present invention
may relate to the capability of being restored with the ability to
flow electrical current at a certain rate for certain,
reestablished time period.
[0045] "Reenergize" and also referred to as "Recharge" as used
herein refer to restoring energy to a state with higher capacity to
do work. Many uses within the present invention may relate to
restoring a device to the capability to flow electrical current at
a certain rate for a certain, reestablished time period.
[0046] "Released From a Mold" as used herein means that a lens is
either completely separated from the mold, or is only loosely
attached so that it may be removed with mild agitation or pushed
off with a swab.
[0047] "Stacked" as used herein means to place at least two
component layers in proximity to each other such that at least a
portion of one surface of one of the layers contacts a first
surface of a second layer. In some exemplary embodiments, a film,
whether for adhesion or other functions may reside between the two
layers that are in contact with each other through said film.
[0048] "Stacked Integrated Component Devices" as used herein and
sometimes referred to as "SIC-Devices", refers to the product of
packaging technologies that may assemble thin layers of substrates,
which may contain electrical and electromechanical devices, into
operative integrated devices by means of stacking at least a
portion of each layer upon each other. The layers may comprise
component devices of various types, materials, shapes, and sizes.
Furthermore, the layers may be made of various device production
technologies to fit and assume various contours, as it may be
desired.
[0049] "Three-Dimensional Surfaces" as used herein, refers to a
property of a surface at a macroscopic level to be non planar in
portions of its extent. The surface of a sphere or a human eye, for
example, would be a three-dimensional surface since the points on
such a surface to do not generally reside in a single plane. The
surface of a typical electronic circuit-board may be a surface that
is not a three-dimensional surface since such boards are typically
planar in nature; even if at a microscopic level they are not
perfectly planar.
Three-Dimensional Devices with Incorporated Semiconductor
Devices
[0050] Numerous novel devices may arise from the integration of
thin and flexible pieces of semiconductors into components and
devices that require certain three-dimensional shapes. In an
example of one such device type, ophthalmic devices that may
incorporate electroactive components are considered.
[0051] Referring to FIGS. 1A and 1B, an exemplary three-dimensional
substrate 100 for an exemplary ophthalmic device is depicted.
Different ophthalmic device embodiments may be formed upon the
exemplary three-dimensional substrate and may be functionalized to
include an active focusing element. The active focusing device may
function while utilizing energy that may be stored in one or more
energization elements. Traces upon the three-dimensional substrate
may be used to provide a good base to form energization elements
upon and upon which to affix, attach or support semiconductors.
Semiconductor devices may be sufficiently thinned to have some
ability to be bent, or otherwise deformed, to fit in more conformal
manners upon three-dimensional surfaces. Additionally, general
aspects of exemplary three-dimensional systems, methods, apparatus,
and resulting exemplary devices related to these concepts will be
described.
[0052] In the exemplary ophthalmic device of FIG. 1, the
three-dimensional substrate may include a region 110 that is
optically active. If the device is a focusing element, the region
110 may represent a front surface of an insert device that
comprises the focusing element through which light passes on its
way into a user's eye. Outside of this region, there may typically
be a peripheral region of the ophthalmic device that is not in an
optically relevant path. Accordingly, it may be appropriate to
place components related to the active focusing function in such a
peripheral region. In some exemplary embodiments, these components
may be formed from thin and flexible semiconductors. Additionally,
the components may be electrically connected to each other by metal
or other conductive traces. The traces may also be used to provide
support for the incorporation of energizing elements into the
ophthalmic device.
[0053] In some exemplary embodiments, the energization element may
be a battery. For example, the battery may be a solid-state battery
or alternately it may be a wet cell battery. In either of these
examples, there may be a minimum of at least two traces, which are
electrically conductive to provide for an electrical current flow
between the anode of the battery and a cathode of the battery. The
battery may provide an electrical potential and current to other
active elements in the device for their energization. In the
exemplary device of FIG. 1, one battery connection may be defined
in the region of an electrical trace 150. For the purpose of
example, electrical trace 150 may be the anode connection and
represent the (-) potential connection of an energization element
to incorporated semiconductor devices. Another battery or
energization element connection 160 may be included. Again, for the
purpose of example, such a connection may represent the cathode
connection. This connection 160 may also represent the (+)
potential connection of an energization element to incorporated
devices.
[0054] At 100, it may be observed that electrical traces may be
connected to items 150 and 160 and items 140 and 170 respectively.
It may be observed that both traces 140 and 170 may be isolated
traces that may lay in proximity to a neighboring trace. The
neighboring trace for 140 may be 130, and the neighboring trace for
170 may be 180. The neighboring traces 130 and 180 may represent
the opposite battery chemistry or electrode type when battery
elements are produced upon these traces. Thus, trace 130 may be
connected to a chemical layer that can make it function as a
cathode of a battery cell between traces.
[0055] Traces 130 and 180 may connect to each other through region
120. Region 120 may in some exemplary embodiments be not covered or
partially covered by chemical layers. It may therefore, function as
an electrical interconnection. It will be apparent that in this
example, there may be two pairs of electrical cells configured as
batteries and that the nature of the layout and design connects
these two batteries in a series connection. The total electrical
performance across connections 150 and 160 may therefore be
considered a combination of two battery cells.
[0056] At 190, a cross section may be depicted of the region along
the dotted line. In the lower representation of 100, a number of
features relevant to the discussion of thin semiconductors are
depicted. In the present exemplary embodiment, at 160, one of the
two energization connections described above is depicted and the
energization connections that occur at 150 may be out of site
behind energization connection 160. A chip form of a semiconductor
is represented as 191 on the figure. For illustrative purposes, the
semiconductor may be connected using solder ball or conductive
epoxy connections to conductive elements on a semiconductor
package. Within the semiconductor package may be located the
semiconductor chip, or the semiconductor chip may be a bare die.
Flip-chip die attach may be used. A device of this type may
function well for the purposes of the exemplary ophthalmic devices;
however, in other applications there may be extra thickness and
area dimensions that such a packaged thick semiconductor chip may
require. Direct connection of a thinned semiconductor to the three
dimensional substrate may allow for the use of less device
thickness, the incorporation of more semiconductor device and other
improvements relating to both the thin form factor and the flexible
nature of thinned unpackaged semiconductors. Although, thinned
pieces of semiconductor may be formed into the similar shape as
they type of chip 191, many other types of shapes and dimensions
may be practical when the flexible nature of thin semiconductors is
considered.
[0057] As a matter of reference, at 192, there may be an area of
the ophthalmic device where a front optic piece as depicted in the
top section of 100 may be joined to a back optic piece. At 192, a
portion of a back optic piece is depicted with region 192 being the
combination of the front optic and back optic with topology that
may provide for one or a set of features to seal components between
the two optic pieces. The set of features in this region where the
sealing will be made is referred to as a glue groove. As further
discussed in upcoming parts the glue groove region may also be
relevant in other exemplary embodiments where thinned semiconductor
devices may be incorporated into other three-dimensional
structures.
Thinning of Semiconductor Elements
[0058] Referring now to FIG. 2, at 200, the general nature of
processes to thin semiconductor devices that may be used for some
exemplary embodiments of the present invention is depicted. At 210,
a representation of a portion of a substrate of full thickness that
has been processed through a semiconductor manufacturing line is
depicted. Typically, such substrates, not shown to scale, may be
500-900 microns thick depending on a number of factors known in the
art. Substrate 210 may be a monolithic or "bulk" semiconductor type
substrate. As an example, a majority of the thickness of substrate
210 may be composed of highly pure, doped, crystalline silicon
where only a thin surface of the substrate has devices and
interconnects upon it.
[0059] For a variety of reasons, it is generally a standard in the
industry for processed wafers to be thinned before the devices on
the substrate are used. At 220, subsequent to thinning, the
substrate may assume a thickness that may be a fraction of the
starting thickness. This may result in very thin substrates.
Accordingly, the thinned material may be found in the "magnified"
cross section representation made up of layers 235 and 230. Methods
to achieve very thin product results where the ending thickness of
the product may be as thin as 30 microns thick or even smaller are
currently available and known as the state of the art. In an
example of such a thinned product, the two layers may represent a
very thin bulk semiconductor layer 230 and a layer comprised of the
metallization or interconnects 235 for the semiconductor
device.
[0060] Referring to FIG. 2B, a similar thinning process description
is made but for a case where a silicon-on-insulator type of
substrate used. In the substrate, formed by layers 250, 251 and 252
a semiconductor-on-insulator substrate is represented. As known in
the art, there are many types of semiconductor-on-insulator
substrates that may be possible. One example may include, a bulk
layer 250 of very pure crystalline silicon upon which sits a region
of insulator, such as, silicon dioxide 251. Upon the insulator
region, 251 may sit another semiconductor layer 252, which, for
example, may comprise a couple hundred-angstrom thick layer of
silicon. The combination of layers provides an example of a
semiconductor (silicon) on insulator (silicon dioxide)
substrate.
[0061] Since the semiconductor (silicon) top layer may be very
thin, numerous methods may be used to thin the entire substrate as
a whole. In an example, the back silicon layer 250 may be ground
away in a grinding operation to where its residual thickness is
nominally zero thickness. In practice, such a grinding operation
may have non-uniformities inherent and there may be regions of
residual silicon on the backside. As a result, additional
processing, for example, through reactive-ion etching, may be used
to selectively remove the silicon and not remove the silicon
dioxide. After the processing, the remaining substrate 260 may be a
very thin combination of the device layer 272 and of an insulator
layer 271, which is what is left of layer 251. Upon the thin oxide
layer may be the thin semiconductor layer 272 (formerly 252 before
the depiction of thinning). Upon this layer may be the
metallization or interconnect layers 275 of the semiconductor
device.
[0062] When a device is thinned as represented in the device with
layers 230, and 235 or with the layers 271, 272, and 275 there may
be a number of properties that result. In a first major discussion
point herein, the thin substrate may assume a degree of flexibility
that is not typical of full thickness substrates. Within certain
limitations, the thin substrate may be deformed to conform to other
three-dimensional substrates upon which they may be affixed. In the
process of deformation, there may be some added defectivity of the
device, which amongst other aspects, may be a function of the
degree of bending and the nature of the circuit design. In some
exemplary embodiments, different design features may be
incorporated to compensate where the degree of deformation
necessary for the application results in any small but tolerable
increases in defectivity.
[0063] Another important aspect of thin substrates is that the
degree to which light, even in the visible spectrum may interact
with the thinned substrates. Even in cases where the substrate
semiconductor thickness after thinning may still be enough to
absorb the incident light radiation, as may be the case with layer
230, such a layer may have a significant level of photocurrent from
such absorption that may require design changes or other actions to
mask the thin layers from interaction with light. In a non-limiting
example, it may be possible to shield at least portions of the
design through the use of some of the interconnection features that
are made upon the three dimensional substrates as it may be the
case, for example, with feature 170 in FIG. 1.
[0064] Referring back to FIG. 2B, layer 272, which is a thin
semiconductor layer that sits upon an insulator layer 271, may be
transparent to incident light. Further, it may be possible for a
significant fraction of the incident light to proceed through both
the insulator layer 271 and the semiconductor layer 272. If
specialized metallurgy, as for example formed from Indium Tin Oxide
or other "transparent metals," were used it may be possible to
create thin electronic layers which may be flexible and use
semiconductor-on-insulator substrates where the semiconductor layer
is very thin and transparent. Additionally, using this type of thin
and transparent device, it may be possible to attach electronic
layers in portions of the ophthalmic device where light may pass
through the ophthalmic device and into the eye.
[0065] When the semiconductor devices become thin, they may become
flexible. This flexibility is a factor discussed in some of the
inventive art herein. Nevertheless, there may be some limitations
to flexing the devices or alternately there may be some additional
defect modes that occur in devices when they are flexed. Therefore,
although some of the depictions of flexing of the device
semiconductor have and will in later sections be referred to where
there is a significant degree of bending, the back support for the
bent pieces may be important in the stabilization of the device
into a relatively rigid piece after it has been flexed onto a
three-dimensional structure.
[0066] In any of the various exemplary embodiments relating to the
flexing of the thinned semiconductor element so that it matches a
three-dimensional surface feature, the flexed device may need to be
adhered to lock the bent configuration into place. In some
exemplary embodiments, the device may be attached using
interconnection technology. For example, solder balls may be used
to adhere contacts on the flexible semiconductor element to
matching contact features which can be located on the
three-dimensional surface. In some cases, these contact points may
provide an electrical function, in other cases, they may be present
for providing means for attachment of the flexible element, and in
still other cases, they may provide both functions. Subsequent to
bonding the contact features, the resulting structure may have an
adhesive material undercoating. In undercoating, an adhesive may be
caused to flow into the vacant space between the flexible element
and the three-dimensional substrate. In some exemplary embodiments,
where the interconnection between the flexible element and
electrical interconnects in the device is not performed between the
flexible device surface and its corresponding surface feature on
the three dimensional substrate, adhering the flexible substrate to
the three-dimensional surface with an adhesive may be a means of
affixing the element. Numerous bonding and adhesive techniques can
be used to affix and stabilize a flexible thinned semiconductor
piece.
Ophthalmic Three Dimensional Device Relevance to Flexible
Elements
[0067] Referring now to FIGS. 3A and 3B, at 300, a second three
dimensional device for use in ophthalmic devices is depicted. At
302, the material, which may preferably comprise a hydrogel polymer
that the ophthalmic device may be formed from, is depicted. An
insert including an electroactive optic region 303 may be included
within the polymerized hydrogel material 302. An interconnection
device 301 may be wrapped around the edge of the electroactive
optic insert. In some examples, the interconnection device may
fully wrap around the insert, or in other examples the
interconnection device may wrap around a portion of the insert. The
interconnection device may be a three-dimensional formed polymeric
piece upon which interconnects may have been deposited or otherwise
formed. When the piece 301 is formed, it may be formed with
features that may be described as flaps 304. The flaps 304 may also
be observed in cross-section at 306 in FIG. 3B, where a formed
cylindrical design 305 surrounds the insert with the electroactive
device 307.
[0068] The flaps and the deposited interconnects may form good
surfaces upon which to attach and connect flexible thin
semiconductor devices. As depicted, a flexible semiconductor device
341 may be a relatively large device that may be attached upon one
of the flap features. Alternately, in some exemplary embodiments
numerous thin strips of semiconductor device may be connected on a
flap type feature as shown at 321 and 322. In each of these cases,
due to the flexibility of both the flaps and the electronic
devices, the electronic devices may be bent into a
three-dimensional shape. It may be helpful to consider such bending
to be occurring across two dimensions, for example both radially in
the direction radiating out from the center of the ophthalmic
device and also in a perpendicular direction to the radial
direction. Since the flap features have significant space between
themselves, another characteristic of such a support and assembly
design may be that the ophthalmic lens may include a significant
portion of its body made from oxygen permeable hydrogel material
which may provide for oxygen penetration benefits for the eye.
[0069] Referring to FIGS. 4A and 4B, at 400, a different exemplary
type of mounting scheme for thin and flexible devices is depicted.
In these exemplary depictions, the thin and flexible device may be
attached along portions of an ophthalmic lens insert in a radial
fashion. That is the flexible semiconductor may be wrapped around
circular features forming, for example, a tube-like feature when
the flexible semiconductor is long enough to reach from beginning
to end. At 410, a cross-sectional representation depicts a portion
of the flexible thin semiconductor wrapped around and adhered to a
three-dimensional surface feature of the glue groove (see for
reference item 192) of a front optic piece (see for reference item
100). In another similar exemplary embodiment, at 440, the flexible
semiconductor may be wrapped around a more exterior edge 450
thereby allowing access to more area by virtue of the increased
diameter and hence circumference.
[0070] When semiconductor pieces are wrapped in such a tube-like
manner, the bending of the semiconductor may be characterized as
happening along one dimension. The depictions of FIGS. 4A and 4B
may be described as being oriented in cylindrical-like features
where the semiconductor sits in a vertical orientation. At any
local region of a point along the surface of a flexible
semiconductor in this vertical orientation, the surface will
"appear" flat in a vertical direction but in the orthogonal
direction, the surface is bending. The degree of the bending is a
function of the radius of curvature of the surface that the
semiconductor may be mounted to, and therefore, at 420 the
semiconductor may be more "bent" or flexed or stressed than at 450.
At a microscopic level, there may be asymmetric stresses that occur
in the semiconductor bulk and other corresponding elements of the
device, like for example, the metal interconnects.
[0071] Referring now to FIGS. 5A and 5B, at 500, another type of
flexibly mounted semiconductor is depicted. In both the orientation
depicted at 520 in cross-section 510 and in the orientation
depicted at 550 in cross-section 540 the flexible semiconductor can
be arranged into conical arrangements. However, starting pieces of
silicon to form a cone may be curvilinear rather than rectilinear.
The degree of bending of the semiconductor layer may be similar to
that of the radially bent semiconductor devices that were mentioned
above. However, since the pieces are curve-shaped before they are
applied, the nature of the bending at a microscopic level will be
different and in some exemplary embodiments may provide a defect
level advantage.
[0072] Other physical attribute advantages of a conical placement
of flexible thinned electronics may occur. In some exemplary
embodiments of a three-dimensional object that receives thinned
semiconductor devices, the overall thickness of the
three-dimensional object, including both the support and the
attached devices, may be important. In flap-type embodiments, the
added height of the attached electronics to the substrate flap may
be minimal, in some implementations this minimal thickness addition
may be close to the thickness of the electronic device. In flap
implementations the limitations on the size parameters of the
semiconductor device piece may not be severe. On the other hand,
for a cylindrical-shape flexible semiconductor, in fact it may be
possible to have an embodiment where there is no net add of
thickness to the ophthalmic device since the effects of device
thickness and interconnect may be radially distributed. However, in
some exemplary embodiments that include a radial piece
implementation, the maximal width (arbitrarily chosen as the
dimension in the mentioned vertical dimension) of the thinned
semiconductor device may be significantly constrained; being less
than 50 microns. A conical shaped embodiment may have
characteristics of these types that are in between the two
mentioned embodiments. There may be some added height to the
ophthalmic device since, based on the angle of the conic section,
some of the thickness will not be distributed radially.
Alternately, by the same effect of the angle of the conic section,
the width of the semiconductor device may also be wider than a
purely radial or cylindrical shape type implementation.
[0073] Referring now to FIG. 6, at 600, an orientation, which has
been an example for stacked integrated devices in prior disclosures
of the same inventive entity, may be relevant to review in the
context of three-dimensional, attached semiconductor devices. It
will be clear to one skilled in the art from this disclosure that
all of the exemplary embodiments that have been discussed thus far
have relevance to stacked device implementations, but for ease of
description embodiments with a single layer have be used to
describe the nature of the invention. Nevertheless, there should be
no limitation of the art related to these descriptions and
implementations of stacked devices are consistent with the art.
[0074] Referring back to FIG. 6, at 610 there may be an insert
portion that may represent an active ophthalmic device that may be
controlled by thin and flexible semiconductor devices and energized
by energization elements within the ophthalmic device. The type of
implementation illustrated at 600 may also be referred to as a
trench type of implementation in this disclosure. In some of these
embodiments, the active element and the thin semiconductor devices
are enclosed in a media insert 620. At 660, thinned and flexible
semiconductor device are represented. In these embodiment types,
the semiconductor may assume a roughly flat or planar orientation
as it may be attached to nearly planar surfaces in the ophthalmic
device. The thinner the device is, the less height that may be
added to the overall ophthalmic device. However, for minimal impact
on the ophthalmic device, the width, in this case of the annular
semiconductor region, may be limited. In some exemplary
embodiments, it may be possible for pieces to achieve widths of
0.25 mm and still not significantly add to the dimensions of the
overall ophthalmic device. It is important to note that in
alternate embodiments, a stacked die approach may include conical
structures with increasing and/or decreasing diameters. Like the
cone type implementations; however, the raw pieces of silicon that
must be diced or cut before installing into the ophthalmic device
are curvilinear not rectilinear, which is more common in
semiconductor device implementations. Unlike the previously
discussed implementations since bending of the semiconductor may
not occur in these types of embodiments, there may be less
stress-induced effects in the substrate.
[0075] In the following table some reference estimations and
representations for some typical aspects of the various types of
implementations are given. These numbers are representative and
should not provide limitations for the scope of the inventive art.
However, they may demonstrate differences between the embodiment
types and relative advantages in light of certain parameters.
TABLE-US-00001 TABLE 1 Comparisons of different implementation
types for thin flexible elements on three-dimensional surfaces
Stress Stress Length Width Area Type "X" "Y" Height Shape mm mm
mm.sup.2 Oxygen Cylindrical 0.15 0 Variable Rectilinear ~110 ~0.1
~11 Better 7 mm radius Cylindrical 0.12 0 Variable Rectilinear ~250
~0.1 ~25 Nominal 9 mm radius Flap ~0.15 ~0.15 Near Normal ~4 ~4 ~16
Best Zero Conical 0 < X < 0 Variable Curvilinear ~110 ~1 ~25
Better 6 mm radius 0.15 Trench 0 0 Near Curvilinear ~110 ~1 ~110
Better 6 mm radius Zero
[0076] In the table a "Stress" parameter is given. This may be a
figure-of-merit for comparison purposes. Generally the parameter is
meant to indicate how much bending a substrate may have when
deployed in the given type of implementation, where the measure of
stress is, for a given movement of one mm in a direction, how much
has the substrate been bent from its normal and flat condition. It
may be best to consider a first direction as "X" where the maximal
bending occurs. A second stress parameter "Y" can be based on the
same measurement as mentioned for "X" but in an orthogonal
direction when referenced to the "unbent" substrate.
[0077] The "Height" measurement is meant to imply how much
additional height may be added to the ophthalmic device by the
orientation. The measure is a relative measure as the actual impact
on height is complicated by other factors including how much height
other components in the ophthalmic lens demand. If the width of the
semiconductor piece, for example, in a cylindrical shape type
orientation is less than the needed height of an active ophthalmic
component within the lens insert, then the semiconductor piece may
not add height to the ophthalmic device regardless of its
width.
[0078] The "Shape" parameter indicates the nature of pieces of
thinned flexible semiconductor as they are diced or cut out as
product. Rectilinear type cuts may be more typical of semiconductor
devices as opposed to curvilinear cuts where a bent but straight
line may represent the nature of dicing or cutting of the substrate
to form the device. The "Length" and "Width" parameters are
estimates for ophthalmic device type implementations of how long
and how wide a piece of thinned silicon may be to be consistent
with a given type of implementation. The area estimate is a simple
calculation of the area of a piece with the length and width
estimates. In the rightmost column, a relative estimate is given of
the degree to which a particular design may interact with the
ability of oxygen to diffuse underneath the ophthalmic device, when
it is worn, to the central region of the optically active portion
of the ophthalmic device.
Special Cases of Relatively Transparent, Thinned and Flexible
Semiconductors
[0079] As mentioned herein, some methods may be used to produce a
relatively transparent device including the use of
silicon-on-insulator substrates and transparent conductive or
"metal" films for the metallurgy of the device. When such a device
is employed using the techniques included herein, it may be
possible to place some or all of the flexible device in a region of
the ophthalmic device in the optic path or a portion thereof. In
some exemplary embodiments, the flexible device of this type may be
located, in a non-limiting example, on a trench type placement
where the trench now is located within the optic zone at depicted
in FIG. 7, 700.
[0080] In FIG. 7, at 100 a three dimensional surface
representation, which may be the front optic of an electroactive
optical component for the ophthalmic device is depicted. Now, in
addition to the elements discussed herein, a cylindrical like
feature may be located in the more optically active region 710.
There may be numerous means to locate a flexible substrate, as
presented, including configuring the piece as a cone-type shape or
alternately molding the three-dimensional shape 700, to have a flat
region for support 710. As mentioned, with special techniques to
render the flexible device transparent, it may not interfere with
light in the optic path. Such a thinned and relatively transparent
device may not significantly interfere with vision.
Stress after Bending and Attaching Flexible Semiconductor
Devices
[0081] Referring back to Table 1, the different implementation
types were tabulated for the "estimated stress" parameters. These
parameters were derived using possible bending changes from normal
flat silicon for a 1 mm distance along the flexible device. FIG. 8
provides for a different way of depicting the concepts.
[0082] Referring now to FIGS. 8A-8D, at 800, exemplary
representation of flap, vertical, radial, trench, and conical
designs static bending aspects are depicted. At 810, a flap type
implementation is depicted. In this type of implementation the
flexible substrate may be subjected to stress from bending in two
different orthogonal directions. A representation of a flap may be
made from region 811 where the bending stress, 815 and 816, may be
found in two orthogonal directions. Due to the nature of a flap, in
some embodiments, for it to take up the least space it may assume a
shape consistent with the ophthalmic device body. Such a shape
would sometimes bend both radially and also perpendicular to
that.
[0083] At 820, a representation for bending stress that occurs with
radial bending is depicted. When a flexible piece is bent around a
radial direction 821, it has a bending stress in a direction
tangential to the radial path 825. However, in the direction
perpendicular to that direction, which may be represented as the
direction out of the page, the flexible semiconductor may not be
bent.
[0084] At 830, a cone shaped bending 831 is depicted from a top
view perspective and similarly there may be bending stress in
directions tangential to the radius of the cone 835 and along the
perpendicular the cone can be flat and not bent. However, there may
be some subtle differences. For example, the cone actually has two
different extremes for the radius of bending. The amount of bending
that may occur tangentially to the cone therefore to a certain
degree may vary across the flexible semiconductor piece. Thus, the
stress condition may be somewhat more complicated for this type of
orientation.
[0085] At 840, trench type orientations are depicted. In these
orientations, the substrate will typically have a cut out that
allows for flat mounting of the semiconductor piece 841. In this
type of flat orientation, the substrate may not be subjected to
bending stress like the other orientations. As has been mentioned
in the table, this type of orientation however may require the
semiconductor pieces to be formed in circular or semicircular
pieces. In some cases, the process of forming the semiconductor
pieces without straight edges may subject the peripheral regions of
the device to certain inherent levels of stress but this can be
distinct from the stress induced by the bending modes of other
orientation types.
Interconnection Aspect--Benefits
[0086] The different orientation types may provide for different
methods for electrical interconnections to be formed with other
components within a three dimensional device. As mentioned
previously, an ophthalmic device provides a good example for the
nature of innovations arising from thinned and flexible
semiconductors on three-dimensional surfaces. A thinned and
flexible semiconductor device may need to form interconnections
including, for example, one or more of: other semiconductor devices
within the ophthalmic device, with energization elements, and with
active optical components.
[0087] Referring to FIGS. 9A-9D, exemplary interconnection aspects
900 for different design types are depicted. At 910, is a
representation of an interconnection strategy related to devices on
flap type substrates. At 911, a region of a flexible device which
may be connected relatively easy to adjoining structures is
depicted. It will be apparent to one skilled in the art from the
nature of the discussions related to FIGS. 1A and 1B, that it may
be possible to deposit electrical interconnects upon the surfaces
of three-dimensional substrates. In this, it may be somewhat more
complex since electrical interconnects may be made to flexible
semiconductors along its periphery or its area.
[0088] The exemplary devices depicted at 920, 930 and 940 have a
similar location for interconnects to be formed. These locations
are shown at 921, 931, and 941 respectively. For cylindrical shape
type implementation similar to item 920, a piece of flexible
semiconductor may be connected to an underlying substrate
connecting to features along the radius. In this case,
interconnections may be made anywhere along the periphery and/or
over both the top and bottom portions of the thin flexible
semiconductor as desired. Therefore, some additional embodiments
may be derived by the stacking of thin semiconductor layers upon
each other.
[0089] In the cylindrical shape type of orientation, the thickness
of interconnects that may occur upon one or both the front or the
back of the thin semiconductor device generally do not contribute
significantly to the overall thickness of the ophthalmic device,
which may be an advantage in some embodiments. For example,
interconnects in region 921 may include a number of different types
including solder ball contacts, conductive epoxies, wire bond
strategies and other means of interconnection. As previously
mentioned, in some exemplary embodiments the interconnects may be
directly deposited upon a three-dimensional surface. In addition,
in some cases, a thin flexible interconnect substrate may be
attached to the three-dimensional surface before the thin flexible
semiconductor device is attached. In this type of example, the
flexible semiconductor device may then be attached to the
interconnect substrate. This may be different from the cases where
attachment of the flexible semiconductor device may be made to
interconnects deposited upon the three-dimensional substrate
surface.
[0090] In the example depicted at 930, a conical implementation is
depicted. The situation may be similar to cylindrical shape type
implementations. In general, the devices of thin semiconductor
layers may have more area in them for a given radius with a conical
implementation. However, in some exemplary embodiments, this
configuration may cause the ophthalmic device to thicken some. Or,
alternately, the area available to semiconductor devices may be
limited by the thickness of the ophthalmic device design. The
manners of interconnecting the device to other components may also
be similar to the radial implementation types; however, due to the
angled surface that would result, accounting for interconnections
between the flat surface and other features may be necessary.
[0091] In the example depicted at 940, a flat trench type
implementation is depicted. The interconnects in flat trench type
implementations may generally be more standard when compared to
semiconductor industry packaging norms due to the flat topology of
the thin flexible semiconductor device. Furthermore, while the
flexibility of thin devices may not come into play as much in
trench type implementations, the reduced height of the thinning may
create significant advantages. For example, when there is more than
one device stacked.
Device Aspects of Thinning--Relevance of Photon Effects
[0092] A number of principles and innovative concepts have been
discussed in relationship to the thinning of semiconductor devices
including their enhanced ability to be packed into small regions
and their ability to be flexible, which thereby provides for a
variety of novel embodiments and semiconductor placement on
three-dimensional surfaces. Yet another aspect of thinning
semiconductors may include how they may be altered by their
interaction with light. As a result, in some exemplary embodiments,
the interaction of light with the semiconductor devices may be used
as an active aspect of their function. For example, when the
devices are quite thin, their ability to sense light entering the
back, (non-device) side of the semiconductor piece may be
significantly improved. There may be a number of reasons for this.
In general, the substrate when thick may itself be able to block
light on the back of the substrate from making it to the front of
the device. When thinned sufficiently, light particularly of
wavelengths that are not absorbed significantly may traverse the
substrate. The semiconductor doping level of the substrate may also
affect the absorption characteristics. The doping level also
modifies the distance that charge carriers created by light
absorption may travel in the substrate may be modified. As
substrates are thinned, all these factors are relevant to detecting
a light signal that is incident on the back of the thinned
semiconductor substrate. Another factor of relevance, is that on
the front of the substrate where the devices are located are also
the insulator and metallization levels. These levels have a high
degree of interaction with incident light. Since, the backside of
the substrate may not have these layers, again the ability to sense
light through the back may be improved. Nevertheless, it may be
possible to sense light through either one or both the front and
the back surfaces when the substrate is sufficiently thinned
Additionally, the nature of the geometry of the device compared to
ambient light sources may enhance the effect for both flap and
trench type implementations as they tend to have the most
perpendicular profile to the expectable general direction of
illumination.
[0093] From an opposite perspective, the ability of sensing
photocurrents due to light incident on the back of the
semiconductor devices may indicate that the same effect can occur
in regions of the devices where the presence of a photocurrent may
not be desired and may result in unintended issues affecting the
performance of the semiconductor devices. As a result, in some
exemplary embodiments it may be important to shield the thin
devices. As a non-limiting example, the interconnection metallurgy
may be used to shield out light. In some cases, the metallurgy may
be portions of the interconnect lines. In other cases, the metal
features may be placed for the sole function of blocking light from
getting into the thinned device. It may also be useful, in some
embodiments, to place metallurgy for the blocking of light wherein
the metallurgy has windows or openings in it in regions where
sensing the light is desired.
Reliability Aspects
[0094] In some exemplary embodiments, the thinned semiconductors
disclosed herein may be formed of mono-crystalline substrates. As
the substrate is thinned, the ability to deform without fracture of
the crystalline substrate may become greater. Nevertheless, the
substrate in some embodiments, especially when the degree of
bending may be significant, may provide significant stress from the
bending of flexing which may result in various effects in the
device. Some of the types of effects in the device may result in
various defect modes whose occurrence may be accelerated by the
presence of the stress. An exemplary defect type may be a substrate
related defect induced by stress.
[0095] Another exemplary defect type may relate to the
metallization features that are placed on the semiconductor device.
The metallization lines may be designed and qualified under
standard conditions to carry a certain level of electrical current
density before they experience the potential for early life failure
due to effects like electromigration. In some cases, the
introduction of bending stress may require additional methods to be
followed for the design and production of the thin semiconductor
devices.
[0096] Numerous manners of altering design aspects in embodiments
of thinned and flexible semiconductors may be possible to mitigate
certain effects, including transistor matching, oxide stress,
threshold voltage and the like. Referring now to FIGS. 10A-10C, at
1000 a number of exemplary approaches are illustrated. At 1010, a
representation of redundancy is shown. Redundant copies of the same
element (1011, 1012, 1013 and 1014) are depicted, where the element
may be a single transistor, another circuit element, or a design
block. In some exemplary embodiments, only one or two of the
redundant elements may be used while in other embodiments, the
redundant elements may be connected in parallel or series fashion
to aid in resilience to stress induced defects.
[0097] At 1020, a representation of a different approach of
achieving redundancy where the redundant elements (1021, 1022,
1023, and 1024) may be spatially separated is depicted. This
approach may be useful if the type of defects propagate through the
crystal lattice along crystal boundaries or otherwise would affect
redundant features that are not isolated by distance. Yet another
approach is depicted at 1030, multiple copies (1031, 1032, and
1033) of redundant elements at different locations along the
thinned semiconductor device can be implemented.
[0098] Referring now to FIGS. 11A-11C, at 1100, examples of methods
for designing in robustness to stress-induced defects in the
metallurgy are shown. At 1110, a metal line 1111 on the thinned
semiconductor device may be effective under normal conditions. In
some exemplary embodiments where enough bending stress may occur to
provide defect modes for metallurgy electromigration, one solution
may include the method depicted in 1120. At 1121, a representation
of the same electrical connection function, but in a line that is
made wider than the original case is depicted. Such a solution
would be effective for those modes where the reduction in current
density by the additional cross sectional area may be helpful.
Alternately, another approach is depicted at 1130 where multiple
lines, 1131, 1132 and 1133 may be connected by crossing lines 1135.
Such a network may offer resiliency to defects related to
electrical current density (by increasing the effective cross
section of conduction) as well as those related to defects that may
be induced by the stress alone where redundant paths can be more
important. There may be numerous manners of designing circuit
aspects related to defect production by stress in flexed and bent
thin semiconductor devices.
Helically Shaped Thin Semiconductor Pieces
[0099] Referring to FIGS. 12A-12C item 1200, another
three-dimensional embodiment for the placement of semiconductors on
substrates with three-dimensional shapes is shown. A thin piece of
silicon may be manufactured in an annular shape at 1210. A dicing
operation may cut out the thin piece of silicon into a complex
curvilinear shape that while still flat may be a spiral shape at
1220. Now, the spiral shape may be attached to a
three-dimensionally formed surface of an insert for example as may
be seen at 1230. The three dimensionally formed surface may take
the form of a helix. When the spirally shaped silicon piece is laid
upon the helically shaped supporting surface, a relatively small
and gentle stress may be imparted to the silicon substrate to cause
it to assume the helical shape. Since the helical shape does cause
the silicon to lift in space as it winds radially which may be seen
by the change in vertical location that can be observed between
1231 and 1232, the resulting helix may better matched to the
typical shape of an ophthalmic lens. The result may be an
electronic component that assumes a three-dimensional shape of a
helix with minimal stress imparted to the semiconductor substrate
itself. The illustration at 1230 shows a single helical electrical
component in concert with an insert piece that may be useful for
inclusion into ophthalmic devices. In some exemplary embodiments,
there may also be stacked implementations of helically shaped
pieces and combinations of helical pieces that are attached onto
the substrate.
[0100] The helical shape may have a benefit over trench type
implementations in that multiple complete revolutions may fit in an
insert device therefore allowing for more circuit area. In other
ways, this embodiment may share similar aspects to the previous
embodiments that have been mentioned, in how it may comprise a
three-dimensional insert, how multiple devices of this type may be
stacked, how the thinned semiconductor layer in this form may
interact with light, and in how methods may be utilized to use
redundancy or other stress compensating aspects of design. A
spirally-diced semiconductor device may enable numerous ophthalmic
embodiments when placed into inserts with helically shaped surfaces
to support the diced semiconductor.
[0101] Specific examples have been described to illustrate aspects
of inventive art relating to the formation, methods of formation,
and apparatus of formation that may be useful to form
functionalized elements, such as energization elements, upon
electrical interconnects on three-dimensional surfaces. The
examples are included to serve to provide enablement in conjunction
with the description and are not intended to limit the scope in any
manner. Accordingly, the present disclosure is intended to embrace
all embodiments that may be apparent to those skilled in the
art.
[0102] Although shown and described in what is believed to be the
most practical and preferred embodiments, it is apparent that
departures from specific designs and methods described and shown
will suggest themselves to those skilled in the art and may be used
without departing from the spirit and scope of the invention. The
present invention is not restricted to the particular constructions
described and illustrated, but should be constructed to cohere with
all modifications that may fall within the scope of the appended
claims.
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