U.S. patent application number 14/049738 was filed with the patent office on 2014-02-06 for polymeric material, method of forming the polymeric material, and method of forming a thin film using the polymeric material.
This patent application is currently assigned to International Business Machines Corporation. The applicant listed for this patent is International Business Machines Corporation. Invention is credited to Ali Afzali-Ardakani, Cherie R. Kagan.
Application Number | 20140034939 14/049738 |
Document ID | / |
Family ID | 40159277 |
Filed Date | 2014-02-06 |
United States Patent
Application |
20140034939 |
Kind Code |
A1 |
Afzali-Ardakani; Ali ; et
al. |
February 6, 2014 |
POLYMERIC MATERIAL, METHOD OF FORMING THE POLYMERIC MATERIAL, AND
METHOD OF FORMING A THIN FILM USING THE POLYMERIC MATERIAL
Abstract
An organic semiconductor device includes a thin film comprising
a polycyclic aromatic compound in a polymer matrix, the thin film
including a substantially uniform thickness, such that a thickness
of the thin film varies by no greater than 1.0 micrometer over the
thin film.
Inventors: |
Afzali-Ardakani; Ali;
(Ossining, NY) ; Kagan; Cherie R.; (Bala-Cynwyd,
PA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
International Business Machines Corporation |
Armonk |
NY |
US |
|
|
Assignee: |
International Business Machines
Corporation
Armonk
NY
|
Family ID: |
40159277 |
Appl. No.: |
14/049738 |
Filed: |
October 9, 2013 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
13050519 |
Mar 17, 2011 |
8586971 |
|
|
14049738 |
|
|
|
|
11771854 |
Jun 29, 2007 |
7932128 |
|
|
13050519 |
|
|
|
|
Current U.S.
Class: |
257/40 ;
438/99 |
Current CPC
Class: |
H01L 51/0508 20130101;
C08F 12/30 20130101; H01L 51/004 20130101; C08F 220/18 20130101;
C09D 125/18 20130101; H01L 51/0558 20130101; C08F 112/32 20130101;
C08F 12/26 20130101; C08F 12/22 20130101; C08F 212/32 20130101 |
Class at
Publication: |
257/40 ;
438/99 |
International
Class: |
H01L 51/05 20060101
H01L051/05 |
Claims
1. An organic semiconductor device, comprising: a thin film
comprising a polycyclic aromatic compound in a polymer matrix,
wherein the thin film comprises a substantially uniform thickness,
such that a thickness of the thin film varies by no greater than
1.0 micrometer over the thin film.
2. The organic semiconductor device of claim 1, wherein the
polycyclic aromatic compound comprises a member selected from the
group consisting of oligothiophene, perylene, benzo[ghi]perylene,
coronene and polyacene.
3. The organic semiconductor device of claim 1, wherein the
polycyclic aromatic compound comprises a member selected from the
group consisting of pentacene, tetracene and hexacene.
4. The organic semiconductor device of claim 1, wherein the device
comprises a thin film transistor.
5. The organic semiconductor device of claim 4, wherein the thin
film transistor comprises a channel region including the thin
film.
6. The organic semiconductor device of claim 4, wherein the thin
film transistor comprises: a dielectric material formed on a
substrate; and plural contacts formed on the dielectric material,
wherein the thin film comprising a polycyclic aromatic compound in
a polymer matrix is formed on the dielectric material, and includes
a channel region of the thin film transistor.
7. The organic semiconductor device of claim 1, wherein the thin
film has a thickness in a range from about 5 nm to 200 nm.
8. The organic semiconductor device of claim 1, wherein the thin
film has a thickness in a range from about 10 nm to about 50
nm.
9. The organic semiconductor device of claim 1, wherein the thin
film of polycyclic aromatic compound in a polymer matrix comprises
a thin film of pentacene in a polystyrene matrix.
10. A thin film for an organic semiconductor device, the thin film
comprising: a polycyclic aromatic compound in a polymer matrix.
11. The thin film of claim 10, wherein the polycyclic aromatic
compound comprises a member selected from the group consisting of
oligothiophene, perylene, benzo[ghi]perylene, coronene and
polyacene.
12. The thin film of claim 10, wherein the polycyclic aromatic
compound comprises a member selected from the group consisting of
pentacene, tetracene and hexacene.
13. The thin film of claim 10, wherein the polycyclic aromatic
compound in a polymer matrix comprises pentacene in a polystyrene
matrix.
14. The thin film of claim 10, wherein the organic semiconductor
device comprises a thin film transistor, and the thin film
transistor comprises a channel region including the thin film.
15. A method of forming an organic semiconductor device,
comprising: forming a dielectric material on a substrate; forming
plural contacts on the dielectric material; and forming a thin film
comprising a polycyclic aromatic compound in a polymer matrix on
the dielectric material, the thin film comprising a substantially
uniform thickness, such that a thickness of the thin film varies by
no greater than 1.0 micrometer over the thin film.
16. The method of claim 15, wherein the device comprises a thin
film transistor and the forming of the thin film comprises forming
a channel region of the thin film transistor.
17. The method of claim 15, wherein the forming of the thin film
comprises: depositing a solution comprising a polymeric material
with a pendant polycyclic aromatic compound precursor onto the
dielectric material; removing a solvent from the deposited solution
to form a thin film of the polymeric material with a pendant
polycyclic aromatic compound precursor; and heating the substrate
to form the thin film comprising a polycyclic aromatic compound in
a polymer matrix.
Description
RELATED APPLICATIONS
[0001] The present Application is a Continuation Application of
U.S. patent application Ser. No. 13/050,519 which was filed on Mar.
17, 2011, and which is a Divisional Application of U.S. patent
application Ser. No. 11/771,854 which was filed on Jun. 29, 2007,
now U.S. Pat. No. 7,932,128.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a polymeric material which
may be reliably used to make a thin film (e.g., an organic
semiconductor thin film) having a uniform thickness.
[0004] 2. Description of the Related Art
[0005] Soluble organic semiconductors have attracted much interest
for use in inexpensive low-end electronic devices such as radio
frequency identification (RFID) tags or displays. Among organic
semiconductors, pentacene has shown real potential for having field
effect mobility which rivals amorphous silicon.
[0006] Solution processed pentacene thin film transistors (TFT)
have been formed using soluble pentacene precursors which after
deposition on the surface could be converted to pentacene by
moderate heating (e.g., see U.S. Pat. No. 6,963,080 to
Afzali-Ardakani et al. entitled "THIN FILM TRANSISTORS USING
SOLUTION PROCESSED PENTACENE PRECURSOR AS ORGANIC SEMICONDUCTOR";
and U.S. Pat. No. 7,125,989 to Afzali-Ardakani et al. entitled
"HETERO DIELS-ALDER ADDUCTS OF PENTACENE AS SOLUBLE PRECURSORS OF
PENTACENE").
[0007] However, since solutions of these precursors have very low
viscosity and the molecules have relatively low molecular weights,
uniform (e.g., uniform thickness) thin film coatings of these
compounds are very difficult to form and are sometimes not
repeatable.
SUMMARY OF THE INVENTION
[0008] In view of the foregoing and other problems, disadvantages,
and drawbacks of the aforementioned compositions, methods and
devices, it is a purpose of the exemplary aspects of the present
invention to provide, inter alia, a polymeric material which may be
reliably used to make a thin film (e.g., an organic semiconductor
thin film) having a uniform thickness.
[0009] An exemplary aspect of the present invention is directed to
a polymeric material with a pendant polycyclic aromatic compound
precursor (e.g., a pendent pentacene precursor).
[0010] Another exemplary aspect of the present invention is
directed to a method of forming a polymeric material with a pendant
polycyclic aromatic compound precursor (e.g., a pendent pentacene
precursor) which includes forming a polycyclic aromatic compound
precursor including at least one polymerizable functionality, and
polymerizing the polymerizable functionality to form the polymeric
material with the pendant precursor.
[0011] Another exemplary aspect of the present invention is
directed to a method of forming a thin film. The method includes
depositing a solution comprising a polymeric material with a
pendant polycyclic aromatic compound precursor (e.g., a pendent
pentacene precursor) onto a substrate, removing a solvent from the
deposited solution to form a thin film of the polymeric material
with the pendant precursor, and heating the substrate to form a
thin film of the polycyclic aromatic compound (e.g., pentacene) in
a polymer matrix.
[0012] Another exemplary aspect of the present invention is
directed to an organic semiconductor device which includes a thin
film including a polycyclic aromatic compound (e.g., pentacene) in
a polymer matrix.
[0013] With its unique and novel features, the exemplary aspects of
the present invention may provide a material which may be reliably
used to make a thin film (e.g., an organic semiconductor thin film)
having a uniform thickness.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The foregoing and other objects, aspects and advantages will
be better understood from the following detailed description of the
embodiments of the invention with reference to the drawings, in
which:
[0015] FIG. 1 illustrates a method 100 of forming a polymeric
material with a pendant polycyclic aromatic compound precursor,
according to an exemplary aspect of the present invention;
[0016] FIG. 2 illustrates a method 200 of forming a thin film
(e.g., an organic semiconductor thin film), according to another
exemplary aspect of the present invention; and
[0017] FIGS. 3A-3B illustrate an organic semiconductor device 300,
according to an exemplary aspect of the present invention.
DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS OF THE
INVENTION
[0018] Referring now to the drawings, FIGS. 1-3B illustrate the
exemplary aspects of the present invention.
[0019] An exemplary aspect of the present invention is directed to
a polymeric material with a pendant polycyclic aromatic compound
precursor. The polymeric material may include a polymer such as
polystyrene, or other polymers such as poly(methylmethacrylate),
poly(acrylate) or polyethers. The polycyclic aromatic compound may
include, for example, oligothiophene, perylene, benzo[ghi]perylene,
coronene and polyacene (e.g., pentacene, tetracene, hexacene).
[0020] FIG. 1 illustrates a method 100 of forming a polymeric
material with a pendant polycyclic aromatic compound precursor,
according to an exemplary aspect of the present invention. The
method 100 includes forming (110) a polycyclic aromatic compound
precursor including at least one polymerizable functionality. For
example, the at least one polymerizable functionality may include
one of acrylate, methacrylate, styryl, and vinyl ether.
[0021] Further, forming (110) the precursor including at least one
polymerizable functionality may include reacting a polycylic
aromatic compound (e.g., pentacene) with a dienophile. The
dienophile may include, for example, a compound that has at least
one heteroatom such as N, O or S, connected by a double bond to a
second heteroatom or carbon.
[0022] In particular, the dienophile may include at least one
heteroatom bonded to an aromatic moiety, such as thioxonmalonates,
azodicarboxylates, thialdehyde, acylnitroso and N-sulfinylamides.
For example, the dienophile may include N-sulfinyl-4-styrylamide or
N-sulfinylmetacrylamide.
[0023] Further, the polycyclic aromatic compound may be reacted
with the dienophile at low to moderate temperatures and in the
presence of a catalyst such as a Lewis acid catalyst. The Lewis
acid catalyst may include, for example, titanium tetrachloride,
silver tetrafluoroborate and methyl rhenium trioxide. Any residue
from the dienophile remaining in the product of the reaction may be
removed either by washing with a solvent or by vacuum drying.
[0024] The method 100 may also include polymerizing 120 the
polymerizable functionality to form the polymeric material with the
pendant precursor. The polymerizing 120 may include, for example,
one of light polymerization, free radical polymerization and ionic
polymerization.
[0025] The polymeric material with a pendent polycyclic aromatic
compound precursor may be soluble (e.g., soluble in common organic
solvents) and may have a molecular weight in a range from 2000 to
100000.
[0026] FIG. 2 illustrates a method 200 of forming a thin film,
according to another exemplary aspect of the present invention. The
method 200 may include depositing (210) a solution including a
polymeric material with a pendant polycyclic aromatic compound
precursor (e.g., a pendant pentacene precursor) onto a substrate
(e.g., glass substrate, metal substrate, polymer substrate, silicon
substrate, etc.). The depositing (210) may be performed, for
example, by pouring, spraying, spin-coating, dip-coating, screen
printing, micro-contact printing, doctor blading, etc.
[0027] The solution may include the polymeric material dissolved
(e.g., substantially dissolved) in a solvent (e.g., an organic
solvent). The solvent may include, for example, chloroform,
tetrachloroethane, tetrahydrofuran (THF), toluene, ethyl acetate,
methyl ethyl ketone (MEK), dimethyl formamide, dichlorobenzene,
propylene glycol monomethyl ether acetate (PGMEA) or mixtures of
any of these.
[0028] Further, the solution including the polymeric material may
include a viscosity of at least 50 cps, but no greater than 100000
cps.
[0029] The method 200 may further include removing (220) the
solvent from the deposited solution to form a thin film of the
polymeric material with a pendant polycyclic aromatic compound
precursor. For example, the solvent may be removed by using heat to
drive off the solvent.
[0030] The method 200 may also include heating (230) the substrate
to form a thin film of the polycylic aromatic compound (e.g.,
pentacene) in a polymer matrix. This may be performed, for example,
by heating the substrate to a temperature in a range from about
100.degree. C. to 200.degree. C.
[0031] The method 200 may also include forming the polymeric
material with a pendant polycyclic aromatic compound precursor
(e.g., a pendent pentacene precusor). As described above, the
polymeric material with a pendant polycyclic aromatic compound
precursor may be formed by forming a polycyclic aromatic compound
precursor including at least one polymerizable functionality, and
polymerizing the polymerizable functionality to form the polymeric
material with a pendant polycyclic aromatic compound precursor.
[0032] An exemplary aspect of the method 200 may be represented by
the following scheme:
##STR00001##
[0033] In this scheme, pentacene (I) may be reacted with a
dienophile such as N-sulfinyl-4-styrylamide (II) in the presence of
a Lewis acid catalyst to give the monomeric pentacene precursor
adduct (III). The styryl functionality of the monomeric adduct
(III) may be polymerized in the presence of light or free radical
generators to form polystyrene with pentacene pendant (IV).
[0034] A film of this polymeric material (IV) may then be formed
(e.g., coated) on a substrate and the solvent may be driven off to
form a uniform thin film of this polymeric material. The substrate
may then be heated at a moderate temperature (e.g., 100.degree. C.
to 200.degree. C.) which may result in the formation of pentacene
in a matrix of polystyrene.
[0035] FIG. 3 illustrates an organic semiconductor device 300,
according to the exemplary aspects of the present invention. The
device 300 may include a thin film 310 which includes a polycyclic
aromatic compound (e.g., pentacene) in a polymer matrix (e.g., a
polystyrene matrix). The thin film may have, for example, a
thickness in a range from about 5 nm to 200 nm, and in an exemplary
aspect the thickness of the thin film may be in a range from about
10 nm to about 50 nm.
[0036] Further, the thin film may include a substantially uniform
thickness. For example, a thickness of the thin film may vary by no
greater than about 1.0 micrometer over the entire thin film.
[0037] For example, the organic semiconductor device may include a
thin film transistor (TFT). Such a thin film transistor may be
used, for example, in electronic devices such as radio frequency
identification (RFID) tags or displays. For example, the thin film
transistor may include a channel region (e.g., a p-type channel
region) which includes the thin film.
[0038] That is, the TFT may use a thin film of polycyclic aromatic
compound in a polymer matrix (e.g., pentacene in a polystyrene
matrix), as an organic semiconductor channel. Generally, the TFT
may be formed by depositing a solution including the polymeric
material with a pendant polycyclic aromatic compound precursor on a
substrate (e.g., a highly doped silicon substrate) covered with a
thin film of thermally grown oxide as gate dielectric, and then
heating the solution to drive off the solvent. The substrate may
then be heated to convert the thin film of the polymer material
with a polycyclic aromatic compound precursor to a thin film of the
polycyclic aromatic compound in a polymer matrix. Source and drain
electrodes may then be deposited on top of the thin film of
polycyclic aromatic compound in a polymer matrix film to get a TFT
device.
[0039] The TFT may also include a gate electrode such as a
patterned metal gate electrode formed on a substrate or a
conducting material such as, a conducting polymer, which is then
coated with an insulator. The insulator may include, for example,
an oxide, nitride, a ferroelectric or an organic polymeric
compound.
[0040] FIGS. 3A-3B illustrate an organic semiconductor device 300,
according to an exemplary aspect of the present invention. As
illustrated in FIG. 3A-3B, the organic semiconductor device 300 may
include a TFT having a substrate 20 (e.g., glass, silicon, or
plastic substrate), a layer of dielectric 30 formed on the
substrate 20. The substrate 20 may include, for example, glass,
polyethylenenaphthalate (PEN), polyethyleneterephthalate (PET),
polycarbonate, polyvinylalcohol, polyacrylate, polyimide,
polynorbornene, polyethersulfone (PES), etc. The dielectric 30 may
include, for example, silicon dioxide, silicon nitride, aluminum
oxide, PbZr.sub.x Ti.sub.1-x O.sub.3 (PZT),
Bi.sub.4Ti.sub.3O.sub.12, BaMgF.sub.4, Ba(Zr.sub.1-x
Ti.sub.x)O.sub.3 (BZT) and organic polymeric compounds like
MYLAR.TM., Polyethylene Terephthalate, polycarbonate and
polyimide.
[0041] The device 300 may, for example, be fabricated in at least
two different geometries: top contact and bottom contact geometries
as shown in FIGS. 3A and 3B.
[0042] In the bottom contact geometry of FIG. 3A, a thin film of
dielectric 330 may be formed on substrate 320. Three contacts may
then be formed on the substrate 320 (e.g., contact 331) and
dielectric 330 (e.g., contacts 332, 333), and the thin film
including a polycyclic aromatic compound in a polymer matrix 340
(e.g., pentacene in a polystyrene matrix) may be formed on the
dielectric 330 and contacts 332, 333. The contacts may include, for
example, a metal such as gold (Au), silver (Ag), nickel (Ni),
indium tin oxide (ITO), chromium (Cr), etc. The device can be
rinsed with solvents to remove any unreacted starting materials or
products.
[0043] In the top contact geometry of FIG. 3B, the dielectric layer
330 may be formed on the substrate 320, and the thin film including
a polycyclic aromatic compound in a polymer matrix 340 may be
formed on the dielectric layer 330. Then, contacts 332 and 333 may
be formed (e.g., through a shadow mask).
[0044] In summary, the exemplary aspects of the present invention
may include a polymeric material with pendant polycyclic aromatic
compound precursor which can be deposited from solution into a
uniform thin film and which after removing the solvent(s), may be
converted to polycyclic aromatic compound. In this approach very
uniform coating of polycyclic aromatic compound may be
obtained.
[0045] For example, the polymeric material may be formed by
synthesizing a polycyclic aromatic compound precursor which
includes at least one polymerizable functionality (acrylate,
methacrylate, styryl, vinyl ether, etc.), and then polymerizing the
functionality to form a polymeric material with pendant polycyclic
aromatic compound precursors.
[0046] In an exemplary aspect of forming a polymeric material of
the present invention, pentacene (I) may be reacted with a
dienophile such as N-sulfinyl-4-styrylamide (II) in the presence of
a Lewis acid catalyst to give the monomeric pentacene precursor
adduct (III). The styryl functionality of the monomeric adduct
(III) may be polymerized in the presence of light or free radical
generators to form polystyrene with pentacene pendant.
[0047] The polymeric material may be soluble in common organic
solvents and, depending on its molecular weight, may form a viscous
solution. A film of this polymeric material may then be formed
(e.g., coated) on a substrate and the solvent may be driven off to
form a uniform thin film of this polymeric material. The substrate
may then be heated at a moderate temperature (e.g., 100.degree. C.
to 200.degree. C.) which may result in the formation of pentacene
in a matrix of polystyrene.
[0048] With its unique and novel features, the exemplary aspects of
the present invention may provide a material which may be reliably
used to make a thin film (e.g., an organic semiconductor thin film)
having a uniform thickness.
[0049] While the invention has been described in terms of one or
more embodiments, those skilled in the art will recognize that the
invention can be practiced with modification within the spirit and
scope of the appended claims. Specifically, one of ordinary skill
in the art will understand that the drawings herein are meant to be
illustrative, and the design of the inventive assembly is not
limited to that disclosed herein but may be modified within the
spirit and scope of the present invention.
[0050] Further, Applicant's intent is to encompass the equivalents
of all claim elements, and no amendment to any claim in the present
application should be construed as a disclaimer of any interest in
or right to an equivalent of any element or feature of the amended
claim.
* * * * *