Ex Parte Bhowmik et al

Patent Trial and Appeal Board

Apr 13, 2017

13822050 (P.T.A.B. Apr. 13, 2017)

United States Patent and Trademark Office
UNITED STATES DEPARTMENT OF COMMERCE
United States Patent and Trademark Office
Address: COMMISSIONER FOR PATENTS
P.O.Box 1450
Alexandria, Virginia 22313-1450
www.uspto.gov
APPLICATION NO. FILING DATE FIRST NAMED INVENTOR ATTORNEY DOCKET NO. CONFIRMATION NO.
13/822,050 03/11/2013 Siddhartha Bhowmik 83204383 8299
22879
HP Tnr
7590 04/17/2017 EXAMINER
3390 E. Harmony Road
Mail Stop 35
REMAVEGE, CHRISTOPHER
FORT COLLINS, CO 80528-9544 ART UNIT PAPER NUMBER
1713
NOTIFICATION DATE DELIVERY MODE
04/17/2017 ELECTRONIC
Please find below and/or attached an Office communication concerning this application or proceeding.
The time period for reply, if any, is set in the attached communication.
Notice of the Office communication was sent electronically on above-indicated "Notification Date" to the
following e-mail address(es):
ipa.mail@hp.com
barbl@hp.com
y vonne.bailey @ hp. com
PTOL-90A (Rev. 04/07)
UNITED STATES PATENT AND TRADEMARK OFFICE
BEFORE
THE PATENT TRIAL AND APPEAL BOARD
Ex parte SIDDHARTHA BHOWMIK1
and J. DANIEL SMITH
Appeal 2015-007375
Application 13/822,050
Technology Center 1700
Before ROMULO H. DELMENDO, MARKNAGUMO, and
WESLEY B. DERRICK, Administrative Patent Judges.
NAGUMO, Administrative Patent Judge.
DECISION ON APPEAL
Siddhartha Bhowmik and J. Daniel Smith (“HP”) timely appeal
under 35 U.S.C. § 134(a) from the Final Rejection2 of claims 1—20, which
are all of the pending claims. We have jurisdiction. 35 U.S.C. § 6.
We affirm.
1 The real party in interest is identified as Hewlett-Packard Development
Company, LP (“HP”), a wholly-owned affiliate of Hewlett-Packard
Company. (Appeal Brief, filed 10 February 2015 (“Br.”), 3.)
2 Office Action mailed 2 October 2014 (“Final Rejection”; cited as “FR”).
Appeal 2015-007375
Application 13/822,050
OPINION
A. Introduction3
The subject matter on appeal relates to methods of forming an
opening through a substrate for fluid ejection devices, such as the print head
of an inkjet printer. (Spec. 1,11. 15—20.) According to the Specification, it is
desirable to decrease the spacing between ink feed slots to increase the
number of nozzles (i.e., the resolution) of the printhead. (Id. at 11. 26—30.)
The claimed invention, it is intimated, addresses some of the challenges in
forming the ink feed slots. (Id. at 1. 30.)
The schematic of a fluid ejection device 304 illustrated in Figure 2,
below, will orient the reader to the claimed subject matter.
“7 S r
,-30
“77
35
| 34 39 33 |
=^=^==4 / r~ r~I 41 \ - 40
(Fig. 2 shows an inkjet fluid ejection device}
Ink enters substrate 40 of device 30 from fluid feed slot 41, providing ink to
ejecting element 31 via orifice 33, which is controlled by resistor 34, which
in turn is coupled to a drive signal and electrical ground via lines 35.
3 Application 13/822,050, Method offorming substrate for fluid ejection
device, filed 11 March 2013 as the international stage under 35 U.S.C. § 371
of PCT/US10/53190, filed 19 October 2010. We refer to the
“’050 Specification,” which we cite as “Spec.”
4 Throughout this Opinion, for clarity, labels to elements are presented in
bold font, regardless of their presentation in the original document.
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Appeal 2015-007375
Application 13/822,050
Ink fills nozzle chamber 39, and is ejected through nozzle opening 38 in
front face 37 of barrier layer 36. (Id. at 4,11. 17—31.)
The claimed process concerns the processing of substrate 40 to make
slot 41, including orifice 33. The surface that defines the wide end of the
slot is referred to as the “second face,” while the surface that defines the
narrow end of the slot is referred to as the “first face.” The principal steps
are illustrated in Figures 3F, 3G, and 3H, reproduced below.
Fisc, 8F
Fig. m
{Figures 3F—3H illustrate stages of the forming process. The Figures are
aligned vertically, keeping width WW (see Fig. 3C, not shown here) of the
exposed area of second side 164 roughly constant. (Spec. 7,11. 1—4.)
Otherwise, we presume the figures are not to scale}
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Appeal 2015-007375
Application 13/822,050
Second side 164 of substrate 160 is provided with backside layer or
stack 170, which may include one or more masks or protective layers.
(Spec. 6,11. 20-24.) First side 162 is provided with thin film structure 32
(from which resistor 34 and leads 35 will be formed), orifice/barrier
layer 36, and various protective layers. (Id. at 11. 20-30.) As shown in
Figure 3F, a first portion 152 of opening 150 is formed with substantially
parallel sides, e.g., by laser processing, in substrate 160 from side 164
towards side 162. The width w of opening 152 is less than width WW,
which effectively corresponds to that indicated by the thicker cross-hatched
region surrounding opening 152. (Spec. 7,11. 19-31; see also Fig. 3C, not
reproduced here.) (Although the ’050 Specification appears to be silent on
the matter, width WW appears to correspond to the ultimate width of
opening 150 at second surface 164 of substrate 160, i.e., WW corresponds to
the width of the back-side end of fluid-feed slot 41 shown in Figure 2,
supra.)
Next, as shown in Figure 3G, second portion 154 of opening 150 is
formed completely through substrate 160 to first side 162, e.g., by a dry-etch
process such as reactive ion etching (“RIE”). (Id. at 8,11. 4—15.) In the
embodiment shown, the width of opening 154 is not significantly enlarged
compared to width w of first portion 152.
Then, as shown in Figure 3H, an anisotropic chemical etch process is
used to form third portion 156 of opening 150 in substrate 160. The wet
anisotropic etchant may be TMAH [tetramethylammonium hydroxide] or
potassium hydroxide (KOH), which removes sacrificial layer 174 and
widens the width of opening 150 at second surface 164 to width WW. The
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Appeal 2015-007375
Application 13/822,050
anisotropic wet etch process is said to follow and be defined by crystalline
planes of substrate 160 as a silicon substrate. {Id. at 8,1. 30, to 9,1. 2.)
After the wet anisotropic chemical etch, an isotropic chemical etch
process with, e.g., XeF2, is said to provide “stress relief at intersecting
orthogonal crystalline planes of a silicon substrate of <110> orientation
developed during the anisotropic wet etch process.” {Id. at 9,11. 8—10.) The
isotropic etch process is also said to provide “stress relief by smoothing or
rounding (i.e., eliminating orthogonal comers of) intersecting crystalline
planes of substrate 160 as a silicon substrate.” {Id. at 9,11. 12—14; see also
Fig. 31, which is substantially the same as Fig. 3H, supra.)
Claim 1 is representative and reads:
A method of forming a substrate for a fluid ejection device,
the substrate having a first side and a second side opposite the
first side, the method comprising:
[a] forming an opening [152] in the substrate [160] from
the second side [164] toward the first side [162];
[b] further forming the opening [154] in the substrate to
the first side [162];
[c] anisotropically wet etching the substrate [156],
including
[1] increasing the opening at the second side [164] of
the substrate from a first width [2wi] to a second
width [2W2],
[2] increasing the opening at the first side [162] of the
substrate from the first width [’wi] to a third
width [1W3], and
[3] forming the opening with converging sidewalls
from the second side [164] to the first side [162]; and
after anisotropically wet etching the substrate,
[d] isotropically etching the substrate.
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Appeal 2015-007375
Application 13/822,050
(Claims App., Br. 16; some indentation, paragraphing, emphasis and
bracketed labels added.)
We have adopted the following convention to identify widths of
openings at the two sides of the substrate: sidew„rdinai. Thus, “2wi” reads,
“second side, first width,” and ulW3” reads “first side, third width.” We
emphasize that we use these labels strictly to identify the location at which
the width of the opening is measured at the process step, i.e., in claim 1,
steps [c][l] or [c][2], in which the width is recited.
Remaining independent claims are similar, but because they are
argued separately, in part, and because they illuminate the scope of key
limitations, we reproduce them here for convenient reference in the
discussion infra.
Claim 6 reads:
A method of forming an opening through a substrate [160]
having a first side [162] and a second side [164] opposite the
first side, the method comprising:
[a] forming a portion of the opening [152] in the substrate
from the second side [164] toward the first side [162];
[b] forming another portion of the opening [154] in the
substrate from the first portion of the opening [152] to the
first side [162];
[c] forming another portion of the opening [156] in the
substrate with an anisotropic wet etch of the substrate,
including
[1] increasing a width of the opening at the
second side [164] of the substrate from a
first width [2wi] to a second width [2W2],
[2] increasing a width of the opening at the first side of
the substrate [162] from the first width [’wi] to a
third width [1W3], and
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Appeal 2015-007375
Application 13/822,050
[3] converging the opening from the second side to the
first side; and
[d] forming another portion of the opening in the substrate
with an isotropic etch of the substrate, including
reducing angles of the opening formed through the
substrate.
(Claims App., Br. 17; some indentation, paragraphing, bracketed labels, and
emphasis added.)
Claim 11 reads:
A method of forming a fluid ejection device, the method
comprising:
[A] providing a substrate having a first side, a second
side opposite the first side, and a thin film structure
formed on the first side;
[a] laser machining a portion [152] of an opening into the
substrate from the second side [154] toward the
first side [162], including
[1] forming the opening with a first width at the
second side [2wi];
[b] dry etching another portion [154] of the opening into
the substrate from the first portion [152] of the opening to
the first side [162] of the substrate, including
[1] forming the opening with the first width at the
first side [*wi];
[c] anisotropically wet etching another portion [156] of
the opening through the substrate, including
[1] further forming the opening with a second width
at the second side [2W2] and
[2] further forming the opening with a third width at
the first side [1W3],
[3] [a] the second width [2W2] and
[b] the third width pws]
both being greater than the first width [wi];
and thereafter,
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Application 13/822,050
[d] isotropically etching the opening in the substrate.
(Claims App., Br. 18; some indentation, paragraphing, bracketed labels, and
emphasis added.)
The Examiner maintains the following ground of rejection5,6:
Claims 1—20 stand rejected under 35 U.S.C. § 103(a) in view of the
combined teachings of Kommera,5 6 7 and Maloney.8
B. Discussion
Findings of fact throughout this Opinion are supported by a
preponderance of the evidence of record.
Briefly, the Examiner finds that Kommera describes, in Figures 1—7,
a process meeting steps [a], [b], and [c], but not step [d], the final isotropic
etch recited in independent claims 1, 6, and 11. Kommera Figures 4—7 are
reproduced on the following page. The Examiner finds that Maloney
describes that an isotropic etch, after an anisotropic etch, relieves stress
induced by etching along crystal planes during the anisotropic etch. The
Examiner concludes that it would have been obvious for that reason to
5 Examiner’s Answer mailed 5 June 2015 (“Ans.”).
6 Because this application was filed before the 16 March 2013 effective date
of the America Invents Act, we refer to the pre-AIA version of the statute.
7 Swaroop K. Kommera et al., Formation of a slot in a silicon substrate,
U.S. Patent Application Publication 2009/0053898 Al (26 February 2009)
(issued as U.S. Patent No. 7,855,151 B2 on 21 December 2010; present
inventor SB is listed as a co-inventor on Kommera).
8 John M. Maloney et al., Fabrication methods and structures for micro­
reservoir devices, U.S. Patent No. 7,413,846 B2 (2008).
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Application 13/822,050
conduct an isotropic etch, as taught by Maloney, after the anisotropic etch
taught by Kommera. (FR4—5.)
{Kommera Figures 4—7 are reproduced below.}
Fig. 4
11 Fig. 7
(Kommera Figs. 4—7 illustrate etching a through-hole in a silicon substrate.
The Figures are aligned approximately on the edges of layer 13 defining
opening 18, recognizing that the Figures are otherwise not drawn to scale}
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Application 13/822,050
Kommera Figure 4 shows silicon substrate 12 with front side9 thin
films 11, and on the opposite side, patterned wet-etch mask 13, and dry-etch
mask 14. (Kommera 1 [0006]—[0009].)
As shown in Figure 5, trench 15 is created by laser patterning.
A portion 16 of silicon substrate 12 separates the bottom of trench 15 from
thin films 11. (Id. at 1 [0010].) Importantly, the width of trench 15 is less
the width of slot area 21 defined by wet etch mask 13 [see Figure 3, not
reproduced here]. (Id.) Shelves 17 are said to be incidents of the laser
patterning process, and are not always present. (Id.)
As shown in Figure 6, a dry-etch process is used to deepen opening 15
so “at least a portion of thin films 11 is reached at the front side of silicon
substrate 12.” (Id. at [0011].)
As shown in Figure 7, “a wet etch is used to clean the remaining
silicon from the slot.” (Id. at [0012].) In Kommera’s words, “[t]he wet etch
also removed dry etch mask 14 as well as smoothed out shelves 17 shown in
FIG. 6.” (Id.)
Kommera teaches that the use of the combination of laser machining,
dry-etch, and wet-etch steps “allows slot widths to approach the width of ink
feed holes formed through thin films 12.” (Id. at [0013].)
HP does not dispute the Examiner’s conclusion that it would have
been obvious to conduct an isotropic etching step taught by Maloney after
the anisotropic etch disclosed by Kommera. Instead, HP argues only that
Kommera does not describe the conditions on the widths recited in
9 Kommera uses the term “front face” to refer to the “first face” recited in
the present application. (Kommera 1 [0005].)
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Application 13/822,050
steps [c][l] and [c] [2] of claim 1, or the widths recited in steps [c][l]
and [c] [2] of claim 6, or the widths recited in steps [c][l], [c][2], and [c][3]
in claim 11. HP considers two cases, first, the case in which laser­
processing leaves shelves 17 (Br. 8,1. 24, through 10,1. 14); and second, the
case in which laser processing does not result in shelves 17 (id. at 10,1. 15,
through 11). As will be seen, it suffices to consider only the first case, in
which shelves 17 are left by the laser processing.
HP argues that,
with reference to annotated FIGS. 5 and 6 ... to the extent
trench 15 . . . has a width (e.g., “wl”) at. . . the . . . “second
side”[], and ... to the extent completed slot 18 . . . has a
width (e.g., “w2”) at the . . . “second side”[], a width
(e.g., “w3”) of completed slot 18 at the . . . ‘first side’ [] is
less than the width (“wl”) of trench 15 at the [second side]
(i.e., “w3” < “wl”).
(Br. 8,1. 24, to 9,1. 2.) HP continues,
The width (“w3”) of completed slot 18 at the side of silicon
substrate 12 on which thin films 11 are formed, however, is
not increased from or greater than the width (“wl”) of
trench 15 at the side of silicon substrate 12 on which mask 13
is formed (i.e., “w3” is not increased from “wl”, “w3” is not
greater than “wl”).
(Id. at 9,11. 2-5.)
This argument is not persuasive.
Because anisotropic etch [c] removes dry-etch mask 14 and the silicon
adjacent to wet-etch mask 13, the width of the opening on the second side
after wet etching, [2W2], is larger than before the wet etch.
Similarly, step [c] [2] reads, “increasing the opening at the first side of
the substrate from the first width to a third width.” Similar considerations
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Application 13/822,050
apply, so the first width of the opening at the first side of the substrate,
which we have labeled [1wi], is whatever width the opening at the first side
has at the beginning of anisotropic etching step [c]. Here too, as shown in
Kommera Figures 6 and 7, the opening at the first side of the substrate after
anisotropic etch [c] is larger than it was at the beginning of step [c].
There is no dispute that Kommera Figure 7 shows enlarged
opening 18 with side walls converging from second side 164 to first
side 162, as required by claim 1.
Claim 6, although worded slightly differently from claim 1,
particularly in reciting “portion of the opening,” does not alter the
interpretation of the widths of the openings at the second and first surfaces at
the various stages of the process.
We conclude that HP has not demonstrated harmful error in the
rejection of claims 1 and 6 based on etching processes described by
Kommera that leave shelves 17 at the end of the laser processing step.
Because any embodiment obvious in view of the prior art that is within the
scope of the claimed subject matter renders a claim unpatentable, this
conclusion suffices to affirm the appealed rejections of claims 1 and 6.
Claim 11 is somewhat narrower than claims 1 and 6 in that: the
substrate is required to have a thin film structure on the first side, i.e., the
side that will feed ink to the nozzle reservoir; step [a] requires laser
machining a portion of an opening into the substrate from the second side,
and specifies forming the opening with “first width at the second side”;
step [b] requires dry etching, and “forming the opening with the first width
at the first side”; step [c][l], by anisotropic etching, “further form[s] the
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Application 13/822,050
opening with a second width at the second side”; step[c][2] “further form[s]
the opening with a third width at the first side.” Moreover, after the
anisotropic etching, step [c] [3] requires that “the second width and the third
width both be[] greater than the first width.”
For reasons parallel to those given with respect to claims 1 and 6, the
etching process illustrated by Kommera meets the limitations recited in
claim 11 at least through step [c] [2]. Step [c][3] requires that the anisotropic
etching step result in “the second width and the third width both being
greater than the first width” The “second width” recited in step [c][3][a] can
only refer to the “second width at the second side” [2W2] recited in
step [c][l], which is larger than the first width at the second side [’w2]
because the wet-etch mask is removed, and silicon under the wet-etch mask
is also removed to enlarge the opening at the second side. The “third width”
recited in step [c][3][b] is met in the process illustrated by Kommera in
Figures 6 and 7 because the final opening is wider than at least the width
between shelves 17.
This analysis suffices to affirm the rejection of claim 11.
Again, HP does not raise other arguments for patentability for any
remaining claims. Accordingly, we conclude that harmful error in the
appealed rejections has not been established.
We therefore affirm the rejections of record.
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Application 13/822,050
C. Order
It is ORDERED that the rejection of claims 1—20 is affirmed.
No time period for taking any subsequent action in connection with
this appeal may be extended under 37 C.F.R. § 1.136(a).
AFFIRMED
14