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Home > Nanotechnology Columns > Magda Carvalho PhD, JD > Nanotechnology and Claim Construction: DuPont v. Cabot.

Magda Carvalho
Patent Attorney
Patent Law at M. Carvalho

What does that claim mean? Claim construction is about giving a meaning to each disputed word or phrase in a claim; it is a job for the court. Claim construction disputes arise over the definition of technical terms, grammatical and semantic interpretation. Certain words ordinarily used in claims have acquired specific legal meaning which may be different from common usage. Claim construction is unpredictable. But its outcome usually determines whether the plaintiff has a valid claim, and whether the defendant infringed the patent. By analyzing how courts have decided claim constructions, patent practitioners and inventors learn how to prepare and prosecute better patent applications for appropriate claim construction.

On July 25, the United States District Court for the District of Arizona issued its patent claim construction in the ongoing patent infringement litigation of Cabot Microelectronics' against DuPont Air Products NanoMaterials, LLC.(1) This case has garnered attention since it could be one the first major patent litigation in the field of nanotechnology. This column analyzes the District Court's claim construction of a number of disputed terms and phrases involving five patents owned by Cabot. Also, in this column the European approach to claim construction is separately discussed by a French patent practitioner, Murielle Derrien.

August 25th, 2008

Nanotechnology and Claim Construction: DuPont v. Cabot.

Cabot is the world's largest supplier of high-performance polishing slurries, in a process called either chemical mechanical planarization (or chemical mechanical polishing) (CMP), to the semiconductor industry. Cabot developed and owns several patents on CMP slurries. The competitor DuPont manufactured and marketed certain CMP slurries. In 2006, DuPont filed a declaratory judgment for a determination of non-patent infringement, patent invalidity, and patent unenforceability against Cabot. Cabot believed DuPont has infringed its patents and counter-sued the competitor for damages and injunctive relief.

Why should DuPont v. Cabot be watched? The setting is germane to nanotech companies in two ways. First, the patents were issued before the 2001 rush in nanotech patenting and the claims might be too broad. Second, this is a case where a new product does the same job or accomplishes the same results as described before in the prior art, but it does so in a new way, or with new materials. Claim construction is not predictable. Cabot knew it. In its patent applications, Cabot carefully acted as its own lexicographer and also employed terms within the meaning of the technical dictionaries to avoid future uncertainties. However, the inventor will be stuck by whatever was written and it may hurt as much as help. In presenting its case at the Markman hearing, Cabot tactically defended itself by reminding the competitor that (a) the inventor's lexicography controls (b) phrases determining functions are not the basis for limitations, (c) "a" legally means "one or more," and (d) a court should give deference to another court's interpretation of the same term. The outcome: in the most part, the court accepted definition of specific terms that favored Cabot.

Claim construction in United States.

Claims are the heart of a patent. They determine the scope of the patent owner's exclusive rights; only the technology covered in the claims is protected. They are paragraphs found at the end of the patent document and, are written in a techno-legal jargon peculiar to patent law. Interpreting the claims is the first step in determining whether the patent is invalid or infringed in most patent litigation.

In 1996, the Supreme Court in Markman v. Westview Instruments held that interpretation of the claims is a matter for the court, the Judge bears the responsibility for claim construction—what the words in the claim mean.(2) The Markman decision, in many jurisdictions, added a pretrial phase to litigation known as the "Markman hearing" in which the litigants fight over the meanings of key terms and phrases found in the patent claims. Markman also established two categories of evidentiary roles: intrinsic evidence and extrinsic evidence. The "intrinsic evidence" relates specifically to the patent: Specification, claims and prosecution history. The "extrinsic evidence" includes all other sources such as expert testimony, dictionaries, treatises, and technical writings.

In 2005, in a reminder that the rules on claim construction are not yet settled, the Court of Appeals for the Federal Circuit (CAFC) in Phillips v. AWH revisited the rules on claim construction and established an evidentiary priority method for interpreting claims.(3) The CAFC emphasized that intrinsic evidence, i.e., Specification, claims, and prosecution history should be given greater weight than extrinsic evidence. The Specification is a written description of how to make and use the invention. The claims define the scope of the invention. The prosecution history discloses all negotiations between the inventor and the Patent Office for the grant of a patent.

The CAFC explained that the Specification is the "single best guide to claim meaning" because it describes the invention in full, clear, concise and exact terms; it may reveal a special definition (inventor acted as his or her own lexicographer) or an intentional disclaimer or disavowal of certain subject matter. On the role of claim language, the CAFC held that the courts must consider both the asserted claim and non-asserted claims. The meaning of a disputed claim term must be scrutinized through the context of the claim in which the disputed term appears, through the usage in other asserted and non-asserted claims in which the same term appears, and through the doctrine of claim differentiation (additional limitation in a dependent claim gives rise to a "presumption" that that limitation is not present in the independent claim). Regarding the prosecution history, the CAFC stated that it is less useful than the Specification because it only represents an ongoing negotiation between the patentee and the Patent Office; still it may show how both the inventor and Examiner understood the invention. The Court also reaffirmed that the time for determining the meaning of claim terms is the effective filing date of the patent application.

Regarding why extrinsic evidence is unlikely to result in a reliable interpretation, the CAFC explained that it (a) is not part of the patent, (b) may not reflect the understanding of skilled artisans, (c) may be litigation driven, and (d) may change the meaning that is otherwise dictated by the intrinsic evidence.

DuPont Air Products NanoMaterials v. Cabot

The five patents-in-suit were directed to the ingredients used in the technique CMP. The process of planarization or polishing employs a combination of chemical and mechanical ingredients. First, a chemical ingredient, such as an oxidizer like hydrogen peroxide, is used to weaken the surface of the wafer by creating a thin layer of "rust." Then, a mechanical ingredient, such as alumina or silica, scrubs-off the rust and the result is a flatten surface. Other chemicals may also be included to perform different tasks.

The Carr Patent: "Transition Metal Chelated Salt"

At issue was the meaning of the term "chelate" within the context of "transition metal chelated salt," which is an oxidizer that the inventors have discovered to improve the slurry performance. To overcome the prior art during the patent prosecution, the inventors had expressly defined "chelate" as "a molecule which coordinates to a central metal atom at more than one coordination site and the complexes so formed are chelates." DuPont argued that it was also limited to (a) the salt be "formed in solution;" (b) the atom's multiple coordination sites be on the "same molecule," and (c) "to form a stable ring complex." The court disagreed in part.

Regarding "formed in solution" the court refused to restrict the claim scope absent a clear demonstration that the inventors intended so, even though the Specification discussed a solvent for the salt.(4) About the term "same molecule," the court rejected that the atom's multiple coordination sites were limited to the "same" atom molecule, the general rule being that "a" of "a molecule" ordinarily means "one or more." The inventor's lexicography controlled and favored the inventor. However, on the phrase "to form a stable ring complex," the court agreed with DuPont that a "complex" was formed because the inventor had stated so, Here, is an example when the inventor's lexicography might have self-inflicted a potential wound. But the court refused to further limit it to "stable" and "ring" in the absence of any foundation.

The Grumbine/Mueller Patents (‘288, ‘775, and ‘787 Patents): catalyst and stabilizer to improve slurry performance.

In these patents the inventors have described that the slurry's performance improved by addition of a catalyst and stabilizer. Concerning the disputed term "oxidizing agent," the court agreed with Cabot that the plain meaning as used in the art controlled because both the Specification and prosecution history employed it consistently within the meaning of the technical dictionaries.

As to the word "catalyst," the parties agreed that it meant "a substance that increases the rate of a chemical reaction without being consumed." However, DuPont argued that the catalyst must (i) be "present in less than the stoichiometric amount necessary to react with the oxidizing agent," (ii) function "without undergoing a chemical change," and (iii) "must be able to shuffle electrons efficiently and rapidly between the oxidizing agent and the substrates surface." The court declined to read the first limitation into the claim since during prosecution the Examiner rejected that the "invention was limited to a particular amount of catalyst." This is how the Patent Office understood the invention. The court accepted the second limitation since the prosecution history showed that the inventor had stated that "[an oxidizing agent] is consumed and does not remain unchanged as a catalyst must," and also included chemical dictionary definitions requiring that it "not undergo a chemical change." Here, the inventor was bound by his own statement. On the third limitation, the court found that the inventor's wording described the function of the "catalyst," and therefore it could not to limit the claim under case law precedent.(5)

The term "synergistic combination" had been specifically defined by the inventors. Therefore, under Philips the inventors' lexicography governed.(6)

At issue was whether the "stabilizer" formed complexes with the catalyst, "significantly decreases the rate at which the oxidizing agent decomposes" and also "reduces the effectiveness of the catalyst" as proposed by DuPont. The court agreed with Cabot that definition of "stabilizer" was that found in the dictionary since it had not been either explicitly or implicitly defined by the inventors.(7) On the first limitation, the court agreed with Cabot that the clear language of the Specification referred to "stabilizer/catalyst complex" as an "admixture" of ingredients "whether or not the combination of ingredients forms a complex." The court rejected adding the two other limitations since they merely stated potential results achieved by the stabilizer and because described results do not limit the scope of a claim.(8)

The Neville Patent (the ‘423 Patent): "Stable"

The Neville patent had already been construed by another district court which accepted the patentee's lexicography relating to "stable," but the court also added a temporal limitation to the stability of the slurry.(9) The disputed meaning of Claim 1 which claimed alumina abrasive particles ("aggregates") that are "uniformly dispersed" in a "stable" slurry; but when the "aggregate" particles "re-agglomerate" they form a "cake." Cabot asked the court to adopt the earlier construction of "stable." The court agreed with Cabot, but the court also decided that the temporal limitation should be read into the claim. The court first reiterated that it was not bound to follow the decision of another district court; however, the Supreme Court in Markman indicated the importance of uniformity in claim construction. Accordingly, courts generally have given reasoned deference to another court's claim construction.(10). This is an instance where an earlier claim construction can be of benefit but also might carry along with it some drawbacks.


Philips's majority opinion explicitly stated that "there is no magic formula or catechism for conducting claim construction." Phillips may not be the final word. Meanwhile, inventors and practitioners should draft the Specification in view of Phillips and subsequent court decisions by (a) writing claim terms with the broadest possible meaning supported by the Specification, (b) double-checking for "minor" differences in claim terms from one claim to another in order to assure that they do reflect the desired breadth and scope, (c) defining key terms in the Specification, (d) avoiding conflict between the dictionary meaning and the meaning from the context of the Specification and (e) claiming non-essential limitations in the dependent claims in order to show the breadth of the independent claims.

(1) DuPont Air Products NanoMaterials L.L.C. v. Cabot Microelectronics Corporation, Civil Action No. CV06-2952-PHX-ROS (D. Ariz. 2006), Markman_Order_072508
(2) Markman v. Westview Instruments, Inc. 116 S.Ct. 1384 (1996).
(3)Phillips v. AWH Corp., 415 F.3d 1303 (Fed. Cir. 2005 (en banc).
(4) The court cited Sauders Group, Inc. v. ComforTrac, Inc. and Care Rehab & Orthopaedic Products, Inc., 492 F3d 132 (2007). ("Claims will not be read restrictively unless the patentee has demonstrated a clear intention to limit the claim scope."
(5) The court cited Kahn v. General Motors Corp., 135 F.3d 1472, 1476 (Fed. Cir. 1998) "Claims [however,] may not be limited by functions or elements disclosed in the specification."; see also Phillips, 415 F.3d at 1320 (noting that reading a limitation from the patent specification into the claim is "one of the cardinal sins of patent law); Catalina Mkting. Int'l, Inc. v., Inc., 289 F.3d 801, 809 (Fed. Cir. 2002).
(6) The court cited Phillips, 415 F.3d at 1316.
(7) The court cited Phillips, 415 F.3d at 1312.
(8) Court cited several precedents; Boehringer Ingelheim Vetmedica, Inc. v. Schering-Plough Corp., 320 F.3d 1339, 1346 (Fed. Cir. 2003) ("An intended use or purpose usually will not limit the scope of the claim because such statements usually do no more than define a context in which the invention operates."); Catalina Mkt'g, 289 F.3d at 809 (composition claims do no depend on the "use or purpose" of claimed structure); Kahn, 135 F.3d 1472, 1476 (Fed. Cir. 1998) (claims are not "limited by functions . . . disclosed in the specification."); Tex. InstrumentsInc. v. U.S. Int'l Trade Comm'n, 988 F.2d 1165, 1172 (Fed. Cir. 1993) (language that "merely states the results of the limitation in the claim adds nothing to the patentability or substance of the claim").
(9) United States District Court for t the District of North Carolina in Cabot Corp. v. Solution Tech., Inc., Case No. 3:96CV505-P.
(10) The court cited Visto Corp. v. Sproqit Techs., Inc., 445 F. Supp. 2d 1104, 1109 (N.D. Cal. 2006) (giving "reasoned deference" to claim construction of another district court outside the jurisdiction regarding the same patents); Verizon California Inc. v. Ronald A. Katz Tech. Licensing, P.A., 326 F. Supp 2d 1060, 1069 (C.D. Cal. 2003) (finding a different district court's construction of patent claim terms "persuasive and highly relevant" authority).

Please send your comments to Magda Carvalho at


By Murielle Derrien,
Industrial Property agent
Paris, France.

Please send your comments to Murielle Derrien at

It is worth mentioning that these five U.S. patents have European equivalents. The European patent Office (EPO) grants a European patent for each contracting state [see, for the list of contracting states]. Consequently, Cabot Microelectronics Corporation would have to file a complaint in each of the contracting states in which these European patents have effect and obviously, in each of the contracting states in which these patents may be infringed.

Article 64 (3) of the European Patent Convention (EPC 1973 and 2000 version) states that "Any infringement of a European patent shall be dealt with by national law."

Moreover, according to Article 69 EPC2000 and to the Protocol on the Interpretation of Article 69 EPC which apply to European patents already granted (1), the extent of the protection conferred by a European Patent shall be determined by the claims (2), the description and drawings shall be used to interpret the claims [Article 69 (1) and (2) EPC].

In each of these contracting states, how would a court which is hearing an European patent infringement case interpret and decide the scope and meaning of claims language?

A whole chapter is dedicated to claims in "Guideline for examination in the EPO. (See in particular Part C III 4.1 to 4.22, 6.1 to 6.6).

As an illustration, these guidelines state that " Each claim should be read giving the words the meaning and scope which they normally have in the relevant art, unless in particular cases the description gives the words a special meaning, by explicit definition or otherwise. Moreover, if such a special meaning applies, the examiner should, so far as possible, require the claim to be amended whereby the meaning is clear from the wording of the claim alone. This is important because it is only the claims of the European patent, not the description, which will be published in all the official languages of the EPO. The claim should also be read with an attempt to make technical sense out of it. Such a reading may involve a departure from the strict literal meaning of the wording of the claim.

Any inconsistency between the description and the claim should be avoided if, having regard to Art. 69(1), second sentence, it may throw doubt on the extent of protection and therefore render the claim unclear or unsupported under Art. 84, second sentence or, alternatively, render the claim objectionable under Art. 84, first sentence."

In proceedings before competent courts, differences in the way claims are interpreted have been reported (3). One important point discussed is the notion of equivalents. Although, about 20 years ago, an attempt to define and harmonize this notion was made in Article 21(2) of WIPO's Proposal, in date of December 21st 1990 (4), this notion was introduced into the EPC only recently (Article 69 EPC and Protocol on the Interpretation of Article 69 EPC) (5). Furthermore, no definition of "equivalent" is given in the EPC.

Case law of the Board of Appeal of the EPO emphasises that Article 69 EPC and its Protocol are primarily for use by the judicial organs which deal with infringement cases (6) and substantial differences in the way courts define "equivalents" have been reported (7, 8).

Similarly, whether prosecution history estoppel which is crucial for determining the extent of protection in the US may influence a court's decision remains unclear throughout Europe (9).

With the new provisions of the EPC (EPC 2000), courts may face another level of difficulty when interpreting the scope and meaning of claims language of European patents. Indeed, the time at which claims are expressed is important for interpretation, as previously pointed out by Prof. Franzosi (3): "the words used in the patent are taken in their literal and historical meaning."

Thus, article 138(3) EPC indicates that the proprietor shall have the right to amend the claims of its patent, as the case may be, about 20 years after they were delimited and that, before only one national competent court: "The proprietor of the patent shall have the right to limit the patent by amending the claims in proceedings before the competent court or authority relating to the validity of the European patent. The patent, as thus limited, shall form the basis for the proceedings [Article 138 (3) EPC].

It is important to mention that there is a central procedure allowing the proprietor of a patent to limit its granted patent in each of the contracting states in which these European patents have effect (10).

In this administrative procedure (11), the examining division is responsible for these proceedings [Art. 18(2) and Rule 91EPC] and observations by third parties are possible under Art. 115 EPC. The amended claims have to comply with specific provisions [Article 84 and Article 123, paragraphs 2 and 3 EPC]. However, there is No examination as to patentability of the residual patent under Art. 52-57 EPC. This seems therefore to be left to an individual court's decision in case of dispute, in addition to claims' interpretation.

Together, these provisions may help proprietor of European patents such as Cabot Microelectronics Corporation, to defend its rights in case of litigation in any contracting state.

How courts in each contracting state will interpret and decide the scope and meaning of claims language after limitation, will be of continuing interest.

Acknowledgements: Prof. L. Nuss

(1) Decision of the Administrative Council of 28 June 2001 on the transitional provisions under Article 7 of the Act revising the European Patent Convention of 29 November 2000. Article 1.
(2) Article 69(2) EPC 2000: The European patent as granted or as amended in opposition, limitation or revocation proceedings shall determine retroactively the protection conferred by the application, in so far as such protection is not thereby extended.
Guideline for Examination in the EPO Part C III 4.1 to 4.22, CIII 6.1 to 6.6.
(3) Franzosi. Claim Interpretation In Europe
"(a) (...) a claim shall be considered to cover not only all the elements as expressed in the claim but also equivalents.
(b) An element ("the equivalent element") shall generally be considered as being equivalent to an element as expressed in a claim if, at the time of any alleged infringement, either of the following conditions is fulfilled in regard to the invention as claimed:
(i) the equivalent element performs substantially the same function in substantially the same way and produces substantially the same result as the element as expressed in the claim, or
(ii) it is obvious to a person skilled in the art that the same result as that achieved by means of the element as expressed in the claim can be achieved by means of the equivalent element."
(5) The Protocol on the Interpretation of Article 69 EPC recommends that both, inventor's protection and third parties' interests have to be taken into account. Moreover, it introduces the notion of equivalent in its second article:"…Due account shall be taken of any element which is equivalent to an element specified in the claims".
(6) "Case Law of the Boards of Appeal (Fifth edition 2006). p.245"
T R I B U N A L D E GRANDE I N S T A N C E D E P A R I S 3ème chambre 3ème section No RG : 04/04202 No MINUTE : Assignation du : 12 Mars 2004 Expéditions exécutoires délivrées le : JUGEMENT rendu le 17 Mai 2006.
"…il est constant que deux moyens sont équivalents lorsqu'ils remplissent la même fonction pour conduire au même résultat et ce, malgré des modes de réalisation différents étant précisé que l'ensemble des effets techniques produits par les moyens en cause doivent être de même nature , de qualité et d'efficacité identiques ».
(10) Articles 105 a, b and c, together rules 90 to 96 EPC.
The request for limitation may not be filed while opposition proceedings in respect of the European patent are pending [Article 105a(2) EPC]. The opposition procedure allows, as the case may be, to revoke a patent in all contracting states in which that patent has effect within nine months of the publication of the mention of the grant of the European patent in the European patent Bulletin [Article 99 EPC].
(11) The limitation of European Patents takes effect on publication in European Patent Bulletin (B3 patents) and, and has effect from the outset or ab initio (Article 68 EPC).

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