DETAILED ACTION
Notice of Pre-AIA or AIA Status
The present application is being examined under the pre-AIA first to invent provisions.
Continued Examination Under 37 CFR 1.114
A request for continued examination under 37 CFR 1.114, including the fee set forth in 37 CFR 1.17(e), was filed in this application after final rejection. Since this application is eligible for continued examination under 37 CFR 1.114, and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114. Applicant's submission filed on 03/17/2025 has been entered.
Claim Rejections - 35 USC § 103
The text of those sections of Title 35, U.S. Code not included in this action can be found in a prior Office action.
Claim 21-24, 30, 34, and 39-42 is/are rejected under pre-AIA 35 U.S.C. 103(a) as being unpatentable over Froitzheim (EP 1732142 A1) in view of Gan (Polysilicon emitters for silicon concentrator solar cells).
Regarding claims 21, 30, and 34, Froitzheim discloses a solar cell comprising (See Fig. 1 and 3):
a silicon substrate (3 [0024]-[0039]) having a textured front surface (6 [0024] [0039]) and a back surface (7 [0025]) opposite the front surface, the front surface facing the sun to collect solar radiation during normal operation;
an antireflective layer ([0031]) over the textured front surface of the silicon substrate;
a doped diffusion region (n+ doped layer 17 [0029] or 38 and 39 in Fig. 3) in the silicon substrate, the doped diffusion region proximate to the textured front surface of the silicon substrate, wherein the antireflective layer ([0031]) is formed over at least a portion of the doped diffusion region;
a doped emitter region layer (10 p-type layer [0025]) formed on the rear side to form a backside junction with the substrate (n-type), the doped emitter region layer (p-type) having an opposite dopant type to the doped diffusion region (n-type).
However, Froitzheim does not disclose that the emitter region layer is formed from a polysilicon layer or that the polysilicon layer emitter is formed over a tunnel oxide layer.
Gan explicitly suggested that solar cell performance can be improved if the diffused-emitter is replaced with the polysilicon emitter (see pg. 245, right hand column paragraph).
Gan discloses first forming an oxide layer on the silicon substrate (see pg. 246 (Steps 1-3 and left hand column, oxide layer thickness 20 Angstroms) before depositing the polysilicon layer and polysilicon emitters with low Jo (measure of recombination) and ρc (contact resistance) can be obtained with a very small fraction of interfacial oxide breakup (pg. 249, see Conclusion).
It would have been obvious to one of ordinary skill in the art at the time of the invention to replace the p-type diffused-emitter of Froitzheim with the thin tunneling oxide layer and polysilicon p-type emitter as disclosed by Gan because Gan disclose that this structure reduces surface recombination and improves solar cell performance.
Froitzheim discloses a front contact (16 [0028]) disposed on and in electrical contact with a portion of the doped diffusion region (17 or 38 and 39 in Fig. 3) the front surface of the silicon substrate; and a rear contact (15) disposed on and in contact with the doped emitter region layer.
Froitzheim discloses that front and metal contacts can be formed from screen printed pastes and described a screen printed paste which includes metal particles ([0048], silver for rear metal contacts disclosed).
It would have been obvious to one of ordinary skill in the art at the time of the invention to modify the front contacts of modified Froitzheim to include metal by having the screen printed paste which comprise metallic particles because Froitzheim discloses that the front side contacts can be formed by a screen printed material and screen printed materials which form contacts have metal particles.
Regarding claim 22, modified Froitzheim discloses all of the claim limitations as set forth above.
In addition, Froitzhem discloses wherein the antireflective layer ([0031])
comprises silicon nitride ([0060]).
Regarding claims 23 and 24, modified Froitzheim discloses all of the claim limitations as set forth above.
In addition, Froitzhem discloses comprising a silicon dioxide layer (18 [0030]) formed on the textured front surface of the silicon substrate.
Regarding claim 39, modified Froitzheim discloses all of the claim limitations as set forth above.
In addition, Froitzheim discloses the doped diffusion region (39) in the silicon substrate includes a first doped diffusion region (38) and a second doped diffusion region (39), the first doped diffusion (38) region is located under and in contact with the front metal contact (16), and the first doped diffusion region has a lower sheet resistance than the second doped diffusion region ([0033]-[0035], see Fig. 3).
Regarding claim 40, modified Froitzheim discloses all of the claim limitations as set forth above.
With regards to “wherein the first doped diffusion region is formed from a different dopant source than the second doped diffusion region”, the cited prior art teaches all of the positively recited structure of the claimed apparatus or product. The determination of patentability is based upon the apparatus structure itself. The patentability of a product or apparatus does not depend on its method of production or formation. If the product in the product-by-process claim is the same as or obvious from a product of the prior art, the claim is unpatentable even though the prior product was made by a different process. See In re Thorpe, 777 F.2d 695, 698, 227 USPQ 964, 966 (Fed. Cir. 1985) (see MPEP § 2113).
Furthermore, different dopants will diffuse into region 38 than into region 39 at two different times and thus these are different sources.
Regarding claims 41 and 42, modified Froitzheim discloses all of the claim limitations as set forth above.
Froitzheim discloses that the front metal contact is narrower than the first doped diffusion region and wherein the antireflection layer is formed over the second doped diffusion region and a portion of the first doped diffusion region, whereby the antireflective layer has contact holes through which the front metal contact contacts the first doped diffusion region (See Fig. 3).
Claim 26 and 27 is/are rejected under pre-AIA 35 U.S.C. 103(a) as being unpatentable over Froitzheim (EP 1732142 A1) in view of Gan (Polysilicon emitters for silicon concentrator solar cells) as applied to claims 21-24, 30, 34, and 39-42 above and in further view of Borden (WO 2009/094578 A2).
Regarding claims 26 and 27, modified Froitzheim discloses all of the claim limitations as set forth above.
Gan discloses that the oxide is thermally grown and is around 20 Angstroms (see pg. 246) but does not disclose it is SiO2.
Borden discloses that the tunnel oxide is SiO2 which can be formed by a rapid thermal oxidation process ([0018], see Fig. 2A) and that tunnel oxides can be used in solar cells between doped polysilicon layers and monocrystalline substrates [0016].
It would have been obvious to one of ordinary skill in the art at the time of the invention to modify the thermal oxide grown tunneling oxide layer of modified Froitzheim by having the thermal oxide grown SiO2 tunneling oxide layer of Borden because Borden discloses it can be provided between an emitter and crystalline substrate which is the same purpose desired by modified Froitzheim.
Claim 25, 28, and 29 is/are rejected under pre-AIA 35 U.S.C. 103(a) as being unpatentable over Froitzheim (EP 1732142 A1) in view of Gan (Polysilicon emitters for silicon concentrator solar cells) as applied to claims 21-24, 30, 34, and 39-42 above and in further view of Schmidt (Surface passivation of silicon solar cells using plasma-enhanced chemical-vapour-deposited SiN films and thin thermal SiO2/plasma SiN stacks).
Regarding claim 25, modified Froitzheim discloses all of the claim limitations as set forth above.
In addition, Froitzheim discloses comprising a passivation layer such as a silicon dioxide layer (18 [0030]) formed on the textured front surface of the silicon substrate however, does not disclose a silicon dioxide layer that is thermally grown having a thickness between 10-250 Å.
Schmidt discloses a silicon dioxide layer that is thermally grown (see section 2.3, 900°C) with thickness between approximately 50-300 Å under a silicon nitride layer on a doped silicon layer (see solar cell 4 or 5 in Table 1) on the front surface or the back surface.
It would have been obvious to one of ordinary skill in the art at the time of the invention to modify the passivation layer on the front surface of Froitzheim by replacing it with silicon oxide and silicon nitride stack as disclosed by Schmidt because it can improve solar cell and performance and/or because it is an equivalent structure for replacing a passivation structure on the front surface of a doped silicon surface because Schmidt discloses it is an equivalent structure.
It would have been obvious to one of ordinary skill in the art at the time of invention to have selected the overlapping portion of the ranges disclosed by the reference because selection of overlapping portion of ranges has been held to be a prima facie case of obviousness. In re Malagari, 182 USPQ 549.
Regarding claims 28 and 29, modified Froitzheim discloses all of the claim limitations as set forth above.
In addition, Froitzheim discloses comprising a passivation layer (34 [0034]) formed on the doped polysilicon region layer .
Schmidt discloses a silicon dioxide layer that is thermally grown (see section 2.3, 900°C) with thickness between approximately 50-300 Å under a silicon nitride layer on a doped silicon layer (see solar cell 4 or 5 in Table 1) on an emitter and further discloses that if this structure is constructed on the back surface rear surface contacts can pierce through the SiO2/SiN layer stack to contact the emitter and that this structure serves to passivate the surface.
It would have been obvious to one of ordinary skill in the art at the time of the invention to modify the passivation layer on the back surface of the polysilicon emitter of Froitzheim by passivating it with a silicon oxide and silicon nitride stack as disclosed by Schmidt because it can improve solar cell and performance and furthermore it would have been appropriate to provide openings in these layers so that the rear metal contacts can pierce through them as disclosed by Schmidt because it will allow for the rear contact to contact the doped silicon layer.
Claim 35-38 is/are rejected under pre-AIA 35 U.S.C. 103(a) as being unpatentable over Froitzheim (EP 1732142 A1) in view of Gan (Polysilicon emitters for silicon concentrator solar cells) as applied to claims 21-24, 30, 34, and 39-42 above and in further view of Russell (US 2008/0216893 A1) and in view of Kray (Study on the edge isolation of industrial silicon solar cells with waterjet-guided laser).
Regarding claims 35-38, modified Froitzheim discloses all of the claim limitations as set forth above.
However, modified Froitzheim does not disclose wherein a trench is formed near an edge on the back surface of the solar cell, and the trench is formed through the silicon substrate, doped p-type polysilicon region layer (emitter) and the tunnel oxide layer and the trench separates portions of the p-type polysilicon region layer (emitter).
Russell discloses that edge isolations can be performed at different positions on the solar cell including back sides and serve to electrically isolate the front and rear solar cells from each other ([0042]).
Kray discloses an edge isolation process which includes cutting through the doped emitter layer and into and through part of the substrate (See Fig. 1).
It would have been obvious to one of ordinary skill in the art at the time of the invention to modify the solar cell of modified Froitzheim by having the edge be isolated by cutting through the rear passivation layer, rear emitter layer and part of the substrate as disclosed by Russell and Kray because it will prevent a shunt between edge surfaces.
Th trench of modified Froitzheim will also include a portion of the tunnel oxide being removed since the trench goes from the p-type polysilicon region layer through and into the substrate and the tunnel oxide lies between these two layers.
Claim 43 is/are rejected under pre-AIA 35 U.S.C. 103(a) as being unpatentable over Froitzheim (EP 1732142 A1) in view of Gan (Polysilicon emitters for silicon concentrator solar cells) as applied to claims 39, 40, 41 and 42 above and in further view of Xi (US 4,865,999).
Regarding claim 43, modified Meier discloses all of the claim limitations as set forth above.
Modified Froitzheim does not disclose that the point contacts are dot shaped.
Xi discloses that either point contacts or electrical contact dots can be used as electrical contacts for solar cells (C3/L40-45).
It would have been obvious to one of ordinary skill in the art at the time of the invention to modify the shape of the contacts of modified Froitzheim to have dot contact shape because as disclosed by Xi having a dot like point contact shape is known and one of ordinary skill in the art would have been able to carry out such a substitution, and the results would be reasonably predictable.
Note that the cross-sectional shape of the point contact of modified Meier will have the corresponding the plurality of highly doped regions under the dot-shaped contacts having a dot shape as seen from a plan view of the solar cell.
Response to Affidavit filed under 37 C.F.R. §1.131
The Affidavit by Director Smith has been considered but the new grounds of rejection does not rely on any reference applied in the prior rejection of record for any teaching or matter specifically challenged in the Affidavit.
Response to Arguments
Applicant’s arguments with respect to claim(s) have been considered but are moot because the new ground of rejection does not rely on any reference applied in the prior rejection of record for any teaching or matter specifically challenged in the argument.
Conclusion
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DEVINA PILLAY
Primary Examiner
Art Unit 1726
/DEVINA PILLAY/ Primary Examiner, Art Unit 1726