JP4368472B2 - Pattern forming method and semiconductor device manufacturing method using the same - Google Patents

Description

ポリシクロオレフィン系樹脂に１０％のコール酸エステルを混ぜた材料を用いて、ＡｒＦ露光装置（ＮＡ０．６）を用いて寸法０．１１μｍのパターン形成を行った。上記材料の吸収係数は、０．５／μｍ。
【００７７】
Ｋ＝総原子数／（炭素原子数−酸素原子数）で求められる値Ｋは２．９であった。
【００７８】
上記形成したパターンを実施例１と同様に欠陥検査装置によりパターン剥れ等の検出を行ったところ、８インチウエハ１００枚につき０．６個の割合で剥れが見られた。パターンの割れは１００枚中で全く観測されなかった。以上によりパターン形成方法における低残留応力の感光性材料の適用の有効性が確認された。
【００７９】
[実施例３]
ポリシクロオレフィン系樹脂をベースとする化学増幅ポジ型感光性材料を、４インチＳｉ基板上に回転塗布し８４００Åの薄膜を形成し、実施例１と同様の工程でパターンを形成した。なお、塗膜形成工程においては、２０℃／分の割合で温度を上昇させた後、１２０秒間１５０℃を保持しその後自然冷却を行った。
【００８０】
各温度における応力測定を行い、その結果を図５に示した。温度が上がるに従って、膜中残留応力が緩和されていることが分かる。温度が下がる過程では、感光性材料の膜中残留応力が徐々に強くなっている。膜形成後の残留応力が２０ＭＰａ／μｍ程度の感光性材料薄膜でも、現像時の膜中残留応力が２１ＭＰａ／μｍであった場合は、ＳＥＭ観察によりパターンの割れ剥れは観測されなかった。
【００８１】
この例では、熱処理後の膜内残留応力の変化が膜形成時の膜中残留応力に対して５％であり、第２の発明である１０％以内という条件を満たしている。
【００８２】
[実施例４]
本実施例は、本発明を用いたダイナミックＲＡＭ半導体装置の製造方法に関するもので図２の工程図を用いて説明する。なお、以下の説明は、ＭＯＳ半導体装置の製造プロセスの主要な工程と本発明の関連を示すためのものであり、従って製造工程の全てについて述べたものではない。
【００８３】
図２（ａ）は、この実施例により最終的に得られるＭＯＳ半導体装置の主要部を示す断面図である。ＭＩＳＦＥＴは、ゲート絶縁膜２０１、ゲート電極２０２、ソース・ドレインのｎ型の高濃度不純物領域２０３からなっており、プラグ電極２０４が上記高濃度不純物領域上のシリコン酸化膜２０１及び２１５を貫いて形成されている。
【００８４】
さらに、上記シリコン酸化膜上には電極配線２０５が形成されている。シリコン酸化膜２０６の上に、王冠型キャパシタ２０７が設けられており、コンタクトホール２１６を介して高濃度不純物領域２０３に接続されている。
【００８５】
（アイソレーション及び酸化膜形成）
先ずはじめに、シリコン基板２００上に周知のシャロウトレンチアイソレーションの方法を用いてＳｉＯ₂アイソレーション（フィールド酸化膜）２０８を形成した。その後、ゲート酸化膜２０１を形成した。なお、このゲート酸化膜２０１の組成、構造、膜厚等は適用するデバイスによって最適化することが望ましい。（ＭＩＳＦＥＴ形成）図２（ｂ）、図２（ｃ）を用いて、本発明を半導体装置の製造におけるＭＩＳＦＥＴ形成工程に適用した場合について説明する。
【００８６】
ゲート電極の材料として、厚さ１００ｎｍ程度のタングステン等の低抵抗の高融点金属膜もしくはそのシリサイド膜２１０と、厚さ１００ｎｍ程度の多結晶シリコン膜２１１との複合膜を用いた。
【００８７】
また、周知の自己整合コンタクトを用いる為にゲート電極上にはシリコンナイトライド膜２０９が形成されている。その上に、膜中残留応力が８ＭＰａ／μｍ、膜厚４０００Åのポジ型感光性材料を用いてフォトリソグラフィを行い、パターン２１２を形成した。
【００８８】
上記感光性材料の吸収係数は、０．６／μｍ。Ｋ＝総原子数／（炭素原子数−酸素原子数）で求められるＫの値は３．０であった。感光性材料にはネガ型感光性材料を用いてもよく、感光性材料膜厚は下地の構造やエッチング条件によって変わる。
【００８９】
しかる後、乾式エッチングにより、上記パターン２１２を下地積層膜に転写することにより、ＭＩＳＦＥＴのゲート２１３を形成した。ここでＭＩＳＦＥＴのゲート長は例えば０．１３μｍであり、極性はｎチャンネル型を用いているが、ｐチャンネル型でもよい。
【００９０】
（コンタクトホール形成）
次いで、ＭＩＳＦＥＴのソースもしくはドレインとなる高濃度不純物領域上のシリコン酸化膜２１５ならびに窒化ケイ素膜に開口部を、配線線加工に用いる感光性材料より膜中残留応力が大きい感光性材料を用いて形成した。
【００９１】
厚さ５０ｎｍ程度の窒化ケイ素膜を周知の減圧化学気相成長法（以下ＬＰＣＶＤ法と略す。）により堆積し、次いで厚さ３００ｎｍ程度のボロンとリンを含んだシリコン酸化膜２１５を周知のＣＶＤ法により堆積し、８００℃程度の温度でアニールを施すことによりシリコン酸化膜表面をなだらかにする。
【００９２】
なお、シリコン酸化膜にはボロンやリンを添加したものを用いずＴＥＯＳガスを用いた４００℃程度のＣＶＤによるシリコン酸化膜をもちい、ＣＭＰ（Ｃｈｅｍｉｃａｌ Ｍｅｃｈａｎｉｃａｌ Ｐｏｌｉｓｈｉｎｇ）法等の他の方法で平坦にすることもできる。
【００９３】
この場合、ウエハー全面に渡って平坦なシリコン酸化膜の表面が得られる。更に製造工程の温度を低温化することによって、ＭＩＳＦＥＴのパンチスルーを防止することもできる。さらに、ＭＩＳＦＥＴのソースドレイン領域の高濃度不純物領域２０３は上記窒化ケイ素膜を堆積した後にイオン打ち込みを用いて形成してもよい。これにより、高濃度不純物領域の横方向を調整することができるため、ＭＩＳＦＥＴのパンチスルー防止に効果がある。
【００９４】
以上の膜形成を行なった後、実施例１と同様の方法を用いてリソグラフィを行なった。この時、膜中残留応力が１２ＭＰａ／μｍの感光性材料を用いた。開口部のシリコン酸化膜２１５をエッチングした。
【００９５】
上記材料の吸収係数は、０．５／μｍ、またＫ＝総原子数／（炭素原子数−酸素原子数）で求められるＫの値は３．２であった。この際、シリコン酸化膜２１５のドライエッチングは窒化ケイ素膜をエッチングストッパとし、さらに異方性の窒化ケイ素のドライエッチングにより上記窒化ケイ素膜をエッチングすることで、ゲート電極やフィールド酸化膜に対して自己整合の開口部を形成する。
【００９６】
次いでリンが高濃度に添加された厚さ２００ｎｍの多結晶シリコン膜をＬＰＣＶＤ法により堆積し異方性ドライエッチングによりエッチバックして上記開口部にプラグ電極を形成する。なお、上記プラグ電極２０４に、タングステンや窒化チタンを用いることで電気的に良好な接触を得ることができる。
【００９７】
また、タングステン等の高融点金属を用いる場合はシリコン基板との反応を防止する目的で窒化チタン等のバリヤメタル膜を下層に設けることが好ましい。
【００９８】
（配線形成）
次に、配線２０５となる厚さ１００ｎｍ程度の配線電極を堆積し、感光性材料膜厚が５０００Åで膜中残留応力が７ＭＰａ／μｍの感光性材料を用いて、ホトリソグラフィを行いパターン形成を行った。なお、配線電極の材料としては好ましくはタングステン等の高融点金属のシリサイド膜と多結晶シリコンの複合膜、もしくはタングステン等の高融点金属を用いることができる。
【００９９】
次いで、厚さ２００ｎｍ程度のボロンとリンを含んだシリコン酸化膜２１５をＣＶＤ法によって堆積し、８００℃程度の温度でアニールを施すことにより表面をなだらかにする。
【０１００】
最後に王冠型キャパシタ２０７と、層間絶縁膜のシリコン酸化膜と金属配線としてアルミニウム配線を形成して本発明の半導体記憶装置が完成する。
【０１０１】
以上本発明のパターン形成方法を用いてデバイスの製造工程を行った結果、パターン剥離や割れの少ないパターンを形成することができた。そのため、１０％以上歩留まりの改善したダイナミックランダムアクセスメモリー半導体装置を得ることができた。
【０１０２】
以上、ＭＯＳ ＬＳＩの基本パターンに本発明を適用した例について述べたが、本実施例にとらわれずＬＳＩの他の工程や、さらに他の種類や材質の半導体装置、例えばバイポーラＬＳＩやガリウム砒素系半導体、半導体レーザ等のオプトエレクトロニック素子等に適用することもできる。その場合、被加工材、感光材の種類、露光方法、現像方法、エッチング方法やガス等は変更されるが、これにともない、本発明による反射防止材料の組成及び処理条件等は、本発明の趣旨を逸脱しない限りにおいて最適化することが望ましい。
【０１０３】
【発明の効果】
以上詳述したように、本発明により、少なくとも感光性材料パターンに割れ、剥離が発生しにくい改良されたパターン形成方法及び０．２μｍ以下の微細構造を有し、かつ歩留まりが高く安価な半導体装置の製造方法を実現するという所期の目的を達成することができた。
【０１０４】
すなわち、本発明は、半導体装置の製造におけるリソグラフィ工程において、上記工程中での感光性材料の物理的破壊を防ぎ、上記半導体装置の歩留まり向上を可能とする。大量生産における歩留まり向上に対して、特に効果がある。
【図面の簡単な説明】
【図１】 パターン形成工程の手順を示した断面工程図。
【図２】 本発明の一実施例となる半導体装置の主要部構造及び製造工程を示す断面図。
【図３】 本発明を説明する膜中残留応力とパターン割れ、剥れとの関係を示した特性図。
【図４】 本発明を半導体装置の製造方法に適用したときのホール層とゲート層とに用いた感光性薄膜の膜中残留応力の差と歩留まりとの関係を示した特性図。
【図５】 感光性薄膜の膜中残留応力を熱処理前後で比較した特性図。
【符号の説明】
１０１、２００…基体、 １０２…感光性材料薄膜、
１０４…放射線、 １０５…露光部、
１０６…形成した微細パターン、 ２０１…ゲート絶縁膜、
２０２…ゲート電極、 ２０３…ソース・ドレイン、
２０４…プラグ電極、 ２０５…電極配線、
２０６、２１５…シリコン酸化膜、 ２０７…王冠型キャパシタ、
２０８…フィールド酸化膜、 ２０９…窒化ケイ素膜、
２１０…タングステンシリサイド膜、２１１…多結晶シリコン膜、
２１２…感光性材料パターン、 ２１３…ＭＩＳＦＥＴ、
２１６…プラグ電極。[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a pattern forming method using a photosensitive material.,Manufacturing method of semiconductor device using this methodAnd photosensitive material used in themIn particular, a pattern forming method suitable for photolithography using a short wavelength radiation having a wavelength of 200 nm or less, for example, an ArF excimer laser (wavelength 193 nm) as an exposure light source,Manufacturing method of semiconductor device using this methodAnd new photosensitive materials used for themConcerningIs a thing.
[0002]
[Prior art]
  In the manufacture of a semiconductor device, a photolithography technique using far ultraviolet light as a light source, such as a KrF excimer laser having a wavelength of 248 nm, is used as a pattern forming technique that achieves high circuit integration and throughput. The wavelength of the light source has been shortened for higher resolution, and the introduction of an ArF excimer laser with a wavelength of 193 nm is under consideration.
[0003]
  A polyvinylphenol-based material as a photosensitive material is excellent in etching resistance, mechanical properties, and the like when applied to a pattern forming method using the KrF excimer laser as an exposure light source. However, when it is applied to ArF excimer laser exposure with a shorter wavelength, the exposed optical image cannot be transmitted through the photosensitive material film due to the strong absorption that occurs in response to the ππ * transition of the benzene ring. There is a disadvantage that it cannot be formed.
[0004]
  by the way,Polymethacrylmethylacetate (PMMA) has no benzene ring and is a transparent photosensitive material in ArF excimer laser exposure.This is known,There is a disadvantage that dry etching resistance is insufficient.
[0005]
  theseIn order to overcome the drawbacks, ArF excimer laser exposure uses alicyclics such as acrylates and cycloolefins.hydrocarbonOrganic photosensitive materialProposed.
[0006]
  AndThe photosensitive material is applied onto a substrate, and an energy beam such as an ArF excimer laser is selectively irradiated onto the coating film through an optical mask, and the exposed or unexposed area is selectively selected by alkali development or the like. Generally, a process of forming a pattern by removing the film is used.
[0007]
  When forming a pattern,What removes an exposed part by development is called a positive resist, and what removes an unexposed part is called a negative resist. Resist is used for high sensitivity.In the chemically amplified photoresist used, in general,Acid generatorIs used together. When a cross-linking reaction or the like is caused using an acid generated by exposure as a catalyst, the resist exhibits a negative behavior. On the other hand, when the functional group in the resist changes from nonpolar to polar due to a deprotection reaction or the like, it exhibits a positive behavior.
[0008]
  The optical lithography process technology and materials are described in, for example, “Innovation of ULSI Lithography Technology” published by Science Forum Inc. in 1994.
[0009]
  On the other hand, the internal stresses of metal materials and the like are described in, for example, “Elasticity and material mechanics” published by Yokensha in 1974 and “Graduate Polymer Chemistry” published by Kodansha Scientific for organic materials.
[0010]
[Problems to be solved by the invention]
  ObedienceIn the case where a fine pattern of 0.2 μm or less is formed using a conventional technique, there arises a problem that the photosensitive material pattern or the thin film is cracked, peeled off or falls during the process. Especially for ArF excimer laser exposureOhIt is remarkableIs.
[0011]
  Therefore, the object of the present invention isthesePrior artDisadvantageTheOvercomeIs to do thatOne of the purposesTo provide an improved pattern forming method in which at least a photosensitive material pattern is hardly cracked or peeled off.sois there.
[0012]
  Another object of the present invention is to provide a method for manufacturing a semiconductor device which has a fine structure of 0.2 μm or less and has a high yield and is inexpensive.
[0013]
[Means for Solving the Problems]
  As a result of repeating various studies in order to achieve each of the above objects, the present inventors have used a photosensitive material having physical properties satisfying specific conditions as a photosensitive material used for pattern formation. It has been found that these problems can be solved, and the present invention has been made based on the findings.
  That is, the present invention includes a step of forming a thin film of a photosensitive material on a substrate, a step of selectively exposing the thin film to radiation having a wavelength of 10 to 200 nm, and a development treatment of the exposed or unexposed portion. In the method for forming a fine pattern including a step of removing, the photosensitive material has a K value determined by the following formula from the total number of atoms, the number of carbon atoms and the number of oxygen atoms contained in the photosensitive material: 3.3 or less,
  K = total number of atoms / (number of carbon atoms−number of oxygen atoms)
  Using a material having a residual stress of 15 MPa / μm or less and a radiation absorption coefficient of 1 / μm or less after forming a thin film, the photosensitive material is mainly composed of a cycloolefin-based resin. A method of forming a fine pattern comprising adding at least 10% by weight of one or more stress reducing agents selected from the group consisting of acid esters and lithocholic acid esters, at least an insulating layer and a wiring layer formed on a semiconductor substrate In the method for manufacturing a semiconductor device, the method includes forming a thin film of a photosensitive material on one layer, selectively exposing the thin film, developing the thin film, and forming a predetermined resist mask pattern. The present invention provides a method for manufacturing a semiconductor device, wherein a resist mask pattern is formed using a forming method.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
  Next, the fine pattern forming method of the present invention will be described with reference to the accompanying drawings.
  FIG. 1 is a cross-sectional view of a processed product in each process when a fine pattern is formed by the method of the present invention. First, following the process (a) of forming a thin film 102 of a photosensitive material on a substrate 101, Thin film 102wavelength10~200Selective radiation 104 nmInIrradiationdo it,exposureStep (b), thenBy development processing,This exposure unit 105RemoveForm a fine pattern 106Step (c) is performed. in this case,The exposure unit 105 is selectively removed by development processing.However, by selecting the type of photosensitive material, the unexposed area can be selectively removed by development processing.
[0015]
  As the photosensitive material used at this time, a value K obtained by dividing the total number of atoms in the photosensitive material by (number of carbon atoms−number of oxygen atoms) is 3.3 or less, and the residual in the film after the thin film is formed. It is necessary to use a photosensitive material having a stress of 15 MPa / μm or less and an absorption coefficient for radiation of 1 / μm or less.
[0016]
  And like thisPhotosensitive materialThe base resin isPolyvinylphenol typeLike resinBenzene ringIncluding rings containing only carbon-carbon single bondsAlicyclichydrocarbonBased resinWhat to do is preferable.
[0017]
  Though, AlicyclichydrocarbonAmong the series resins,Carbon-carbon1 double bondThere are things that include this,SometimesRIt can be used.But,Benzene ringThose containing aromatic rings such asLarge absorption coefficientBecausePattern shapeofDeterioration, dimension controllabilityofAuthorBecause it causesIt is not preferable.
[0018]
  AboveAlicyclichydrocarbonResinPreferred examples ofas,Of acrylic acid or methacrylic acidAlicyclicHydrocarbon group esterresin,Cycloolefin resins, norbornene resins, and thesecompositeresinAnd so on.
[0019]
  AndAbove acrylic acidAlicyclicHydrocarbon group esterresinWhenThenPolyAdamantane-based acrylate side chainHydrocarbon groupAnd lactone functional groupButIntroductionWhat was doneFor example, 2-Methyl AdamanTyl acrylate /γ-ButyroLactNilAcrylateresin,2-Methyl AdamanTyl acrylate /MevaloLactonylAcrylateresin2-Ethyl adamantane acrylate/ Γ-butyrolactonyl acrylate resin,AdamanTyl acrylate resin, γ-butyroLactNyl acrylate resin, polyCarbohydrate on acrylate side chainKisilBaseContainsAlicyclicHydrocarbon group and hydroxyl group-containing alicyclic hydrocarbon groupIntroductionWhat was doneFor example, hydroxytricyclodecLeAcrylate/ Carboxytricyclodecyl acrylate resin,TheHydroxytricyclodeciLeAcrylate/ Carboxytricyclodecyl acrylate resin.
[0020]
  theseResin positiveTypeResistUse as resinIf polarityBaseCarbo asVarious types that can be eliminated by acid to the xyl groupProtecting groupFor example t-ButylGroup,EthoxyethylBaseTetrahydrBPyranylGroups can be introduced.
[0021]
  Also, these resinsNegative resistforAs resinIf used,EpoxyBaseThe alicyclichydrocarbonBaseInFor example, epoxy tricyclodecLeAcrylateEtc.Hydroxyl groups as groups that react with the crosslinking agentCan be used.
[0022]
[0023]
  On the other hand, the aboveAcrylateCompatible with resinMethacrylateAs resin,For example, 2-Methyl AdamanChillMethacrylate/ Γ-Butyrolactonyl methacrylate resin, dihydroxyTricyclodeciLeMethacrylateresin2-Methyl AdamanChill methacrylate /MebaBLactNilMethacrylateresin2-Ethyl AdamantChillMethacrylate/ Γ-butyrolactonyl methacrylate resin, diHydroxytricyclodecylAnd methacrylate resins..
[0024]
  next,Of cycloolefin resinExampleAsIsCycloolefinInSide chainAs protectedCarboXyl groupIntroducedOrSide chainAs an alkoxy groupIntroductiondo itImprove adhesionCan be mentioned. As such resin,For example, KarbokiShiNorbornayNil anhydrousMalayAcid resinThe CarbokiShiNorbornayNil anhydrousMalayAcid /Methyl hydroxyShiNorbornayNil anhydrousMalayAcid resinEtc.
[0025]
[0026]
  Also,Of these resinscompositeresinas,For example, cycloolefinWhenAcryLuric acid orMekakuriComposite resin with sulfonate,NoLebornenWhenAcryLuric acid orMekakuriComposite resin with sulfonateEtc.
[0027]
  Next, the fine pattern forming method of the present invention is used.Photosensitive materialAfter thin film formationThe residual stress in the film is 15 MPa or lessIt is necessary, but this is fine formedPattern cracksas well asPeel offIt is a requirement necessary for suppression.
[0028]
  That is,ArF laser exposureByLess than 0.2μm formedSizeFine patternOhThe residual stress in the film of the photosensitive materialButCrackas well asPeelingIs greatly related to the number of
[0029]
  FIG.Is a graph showing the relationship between the number of cracks and peeling in the formed fine pattern and the residual stress in the film, as can be seen from this graph,Residual stress in the film is 15 MPa / μmLarger thanCrackas well asStrippedSuch defectsThe number of occurrencesRapidlyTo increase. For example, 15 MPa / μmDefects inThe rate of occurrence is 0.1 piece / wafer, while 40 MPa / μmDefects inIncidence rate is 2 / waferAnd20 times of 15MPa / μmAnd soaring.
[0030]
  On the other hand, at 15 MPa / μm or less, cracking occurs.as well asPeelingSignificantly lessFor example, at 5 MPa / μmDefectsIncidenceIs0.05 piece / waferIt has become.
[0031]
  Thus, a fine pattern is formedIn processsoCrackas well asPeelingIs the photosensitivity used in this processMaterial inherent stressWhenTensile strengthWhenconnection ofAnd, Heat history during process, adhesion, etc.ButIs involved.
[0032]
  That is,Spin on substratecoatingByFeelingLight materialofForm a thin filmMakeWhen,During coating processAnd thenApplied toBy heat treatmentRPhotosensitive materialDuring ~Solvent evaporatesFor,The volume of the membrane shrinks and enters the membraneContractionStress is generated.And thisThe magnitude of the stress is that of the photosensitive material.moleculeStructure, molecular weightAndsolventType of,Heating conditionsEtc.Depends on.
[0033]
  Also,FeelingLight materialApplyIf its the mainComponentresinConfigure the basicsThe skeleton is rigidif there isThe more the residual stress in the film increasesIncreaseTrendButis there. Especially used for ArF laser exposureRuAlicyclichydrocarbonResin is a conventional KrFDewRigid compared to photosensitive materials for lightFor,NormalResidual stress in the film of 20 MPa / μm or moreShow.
[0034]
  By the wayAlicyclichydrocarbonPhotosensitive materialsExampleFor example, low molecular weight componentsBy mixing as a stress-reducing agentResidual stress in the filmReduceCanit can. And in this wayLow molecular weight componentsWhen mixedOf photosensitive materialGlassThe transition temperature decreases,Helps reduce residual stress in the filmHowever, heat resistance decreasesTrendButis there.
[0035]
  in this way,Low residual stress in filmunderLetRuExamples of stress reducing agents include cholic acid esters and alicyclic groups.carboxylic acidEsters, alcohols, lithocholic esters, alicyclicshydrocarbonMonomer, alicyclicTribeAlcohol, low contentChildCyclic with carboxylic acid functional grouphydrocarbonEtc. are effective.
[0036]
  AlicyclicWith hydrocarbon groupsResin1OneRuCycloolefin resinincludingPhotosensitive materialabout, Stress reducing agent,For example, lithocholic acid ester 10weight% Or moreTheResidual stress in film is controlled to 15MPa / μm or lessTo doit can.Also generally about polymersIncrease molecular weightWhenIncreased ductilitySoBrittleTheImprovementCan be used as photosensitive materialUse a polymer with a molecular weight of 20000 or moreWhenTendency to degrade resolutionButis there.
[0037]
  Aside from that, for various reasonsThe residual stress generated in the filmMe, 0.2μm or lessFineForming a patternMakeWhen developing, the pattern edgeAndStress concentration occursR,to thisrinseAt the time ofsurface tensionButJoinThe residual stress in the film ispatternOvercoming the adhesion of,substrateCauses peeling. AndIn particular, the residual stress in the film exceeds 15 MPa / μmWhen,Pattern peelingMarkedlyBecome.
[0038]
  Meanwhile, crackthe cause ofaboutAs a result of investigation, this isLocal stress concentration in the thin film on the substrateRelated,putterNAbout the crackIt turns out that it has a big influence. That is,Like hole patternIn a circleStress concentration in patterns with large contact areaButHard to happenTherefore, no cracks occur,Close contact parts such as isolated gate patterns and wiring patternsButLess angular patternOhThe corners of the patternPartStress concentration occursEaseFuckFrom the partCrackOrPeeling due to crackingThe occurrence of separation is observed. From these factsReduce the number of cracksForInIsStress in photosensitive materialThesmallThat it is desirable to.
[0039]
  next,Etching resistantConsidering photosensitive resin from the viewpoint,Lithography processManufactures semiconductor devices usingIf the pattern transferWhen doingFor dry etchingCan withstand enoughGet etching resistanceInIsThe above K value3.3 or lessMakeThere is a need.AndthisKThe smaller the value, the more resist maskWhen usingImproved resistance to etchingI found out that This K value isFrom 3.3AlsoAs it increases, the etching resistance decreases significantly.For mask patternAs a resistPerformanceInferiorityIt will be. From this, it can be seen that the K value can be used as a factor for determining the superiority or inferiority of the resist used when manufacturing the semiconductor device.
[0040]
  Furthermore, it uses in the fine pattern formation method of this invention.Photosensitive materialIn order to improve the fidelity to the mask pattern of the latent image when the latent image is formed by irradiating the radiation,Against wavelength,Absorption coefficient of 1 / μm or lessHaveCanIt is necessary and the smaller the absorption coefficient, the better. thisWhen the absorption coefficient is greater than 1 / μm, the pattern shapeBadDimension controllabilityofAuthorCause a decline.In addition,Against this radiationAbsorption coefficient of photosensitive materialIs generally availableOptical deviceEasy measurement usingcan do.
[0041]
  As the photosensitive material used in the fine pattern forming method of the present invention, in addition to the photosensitive material having the physical properties described above, the initial in-film stress σ per film thickness of the photosensitive material thin film₀Is 15 MPa / μm or more, and the in-film stress σ after heat treatment at a temperature of 80 to 160 ° C. and a time of 5 minutes or less_pChanges in initial film stress σ₀Alternatively, a photosensitive material that is 10% or less can be used.
[0042]
  aboveFilm thickness of photosensitive materialHitInitial film stress σ₀ Is15 MPa / μm or moreThere is no particular limit on the upper limit.PracticallyIsAbout 25MPa / μmIs the upper limit.
[0043]
  Use such photosensitive materialThe pattern formation method isIn particularwavelength10~200nm radiationTo form a pattern with a pattern size of 0.2 μm or lessIt is valid.And the latent imageFaithfulEvery timeImproveOf radiationAbsorption coefficient of 1 / μm or less with respect to wavelengthHaveIt is desirable.Use this photosensitive materialThe pattern formation method isIn particularManufacture of MOS semiconductor devicesAt the time ofIt is suitable for a gate layer pattern forming method.
[0044]
  Generally, when forming a pattern,Go through thermal processEveryIn photosensitive materialsSolvent residueDecrease in quantityLessBecauseIn the membraneResidual stress increasesIncrease.further,Positive chemical amplification reaction in membraneAs this progresses, thisreactionsoGenerationDoLow molecular weight componentButVolatilizationdo itResidual stress in filmTheIncreaseLargeThe
[0045]
  And mentioned aboveSo that after film formationInHas a residual stress in the film of 15 MPa or moreWhen,During pattern formation processRemarkableCracking or peelingSeparationButappear.
[0046]
  HoweverWhileFrom the time of film formation, thenApply toTo thermal processIn the film, the residual stress in the film σ ₀ After heat processResidual stress in filmσ _p BetweenRate of change (σ_p−σ₀) / Σ₀Is less than 10%InCracking or peeling during the processSeparationButBe reduced.
[0047]
  That is,patternPeelingDevelopment and rinsing processHappens inWhen the residual stress change in the film during the thermal process is 10% or less, the maximum stress value of the portion where the stress concentration occurred is when the material whose residual stress change in the film during the thermal process is 10% or more is used. It becomes smaller than the maximum stress value of the same pattern part.
[0048]
  AndBy thermal processRuStress changeMake smallerUse a highly volatile solventUse,GlassUse material with low transition temperatureJust do.
[0049]
  Normal,When providing a resist thin film,Used for photosensitive materialsTheOrganic solventTo removeA temperature of 80 ° C. or higher is used.However,160 ° C or higherWhen heated to a resin component of the photosensitive materialBetween polymerssoReactions such as crosslinkingOccurs, sensitivity and moldabilitySpoiledBe calledFor,FeelingFor optical materialsThe applied temperature is80 to 160 ° CTo choose betweenpreferable.
[0050]
  Therefore, it is appropriate to select heating for a predetermined time in the temperature range of 80 to 160 ° C. as a reference for the rate of change of the in-film stress.
[0051]
  Radiation of the above photosensitive resin when selective exposure processingwavelength10 as a range~200nm is desirableAgainPhotosensitivitysexThe absorption coefficient of the material is also desirably 1 / μm or less.
[0052]
  And generally, when forming a resist thin film,In process as film thickness increasesOccur inThin film crackingBecause the number of occurrences increasesOf a film thickness of 1.5 μm or moreWhen forming a resist thin film,1.5μmForm a resist thin film with a thickness less thanIf compared toIn addition, in the membranestressUse a photosensitive material that reduces theis required.
[0053]
  Next, a method for manufacturing a semiconductor device using the above-described fine pattern forming method will be described.
[0054]
  According to the method of the present invention, the semiconductor device isSecond on the boardoneUsing photosensitive materialoneForming a thin film,
  SaidoneThin filmThewavelength10~200nm radiationInSelective exposureMakeProcess,
  The exposure unitOrThe unexposed area is selectively removed by development processing.oneForming a mask pattern,
  SaidoneEtching the substrate using the mask pattern of,
  On the substratetwoUsing photosensitive materialtwoForming a thin film,
  SaidtwoThin filmThewavelength10~200nm radiationInSelective exposureMakeProcess,
  The exposure unitOrThe unexposed area is selectively removed by development processing.twoForming a mask pattern,as well as
  SaidtwoA method of manufacturing a semiconductor device, comprising: etching the substrate using a mask pattern ofOr forming a first thin film on a semiconductor first substrate using a first photosensitive material;
  Exposing the first thin film to radiation having a wavelength of 10 to 200 nm via a first optical mask, and transferring a mask pattern;
  A step of selectively removing the exposed portion or the unexposed portion by a development process to form a first mask pattern;
  Etching the substrate using the first mask pattern;
  Forming a second thin film on a second substrate of the semiconductor using a second photosensitive material;
  Exposing the second thin film to radiation having a wavelength of 10 to 200 nm through a second optical mask, and transferring a mask pattern;
  A step of selectively removing the exposed portion or the unexposed portion by a development process to form a second mask pattern; and
  A method of manufacturing a semiconductor device including a step of etching the substrate using the second mask pattern.
  When the thin film is formedoneΣ is the residual stress in the film of σ₁The secondtwoΣ is the residual stress in the film of σ₂The difference between the two(σ₂−σ₁ )2 MPaMore thanthingCan be manufactured by.
[0055]
  UpRecordofsemiconductorIn the manufacturing method, the first mask pattern is a MOS type semiconductorapparatusInFor the gate part creation insecondThe mask pattern is used when creating other areas.Preferably used.
[0056]
  In the manufacture of semiconductor devices, the same layerOhPatterns such as holes that are less likely to cause stress concentration in the photosensitive material, and pattern removal due to stress concentration in the photosensitive material.SeparationAnd cracksofHappenEasePatterns may coexist. In the above case, the pattern shape for the same layerEveryIn addition, by optimizing the stress of the photosensitive material and performing microfabrication multiple times,Prevent cracking and peelingTo improve product yieldCanThe
[0057]
  In particular, dot patterns, isolated gates, wiring patterns, etc.Easy to peelWhen creating a shape, use a pattern such as a hole.PeelingBeginning ofGarlicThe residual stress value in the film during film formation is small compared toOrBy using a photosensitive material film having a difference of 2 MPa or more, pattern peelingSeparationCan improve the degree ofCanThe
[0058]
  By the method of the present invention,MOS type semiconductor deviceTheManufacturingDoIn this case, it is desirable to use a photosensitive material having a lower stress than other layers for forming holes or the like for pattern formation of the gate and wiring layers.
[0059]
  Figure4These are graphs showing the relationship between the difference (MPa / μm) in the residual stress in the film of the photosensitive material thin film used for the hole layer and the gate layer and the yield (%) when the semiconductor device is manufactured by the above method. . As you can see from this figure,Gate layer (aboveoneResidual stress σ in thin film₁To the hole layer (above)twoResidual stress σ in thin film₂Yield can be improved by using a photosensitive material having a small residual stress in the film of 2 MPa / μm or more.Can(Σ₂−σ₁≧ 2 MPa).
[0060]
[0061]
  Used in these methodsPhotosensitive material is exposedRadiation used forIt is desirable to have an absorption coefficient of 1 / μm or less for light. When applying the above method to the manufacture of a MOS type semiconductor device,oneThe substrate is a gate and a wiring layer, and the firsttwoWhen the substrate is applied so as to be a layer other than that, further effects can be obtained.
[0062]
  In the manufacture of semiconductor devices, the layers formed on the substrate,is thereseedThe pattern of the shape may become dominant. On the other hand, reducing the residual stress in the film of photosensitive materialForIn addition, when a low molecular weight component is added to the photosensitive material, the dry etching resistance tends to be impaired.
[0063]
  Therefore, by optimizing the stress of the photosensitive material according to the shape of the pattern, patterns such as holesPeelingBeginning ofGarlicFor patterns with large shapes, a material with high dry etching resistance is used even if the residual stress in the film is large. Conversely, although the conditions for dry etching are mild, stress concentration occurs.EaseHigh yield can be obtained by using a photosensitive material with low residual stress in the film for the layer where the gate pattern and wiring pattern are dominant.CanThe
[0064]
  Especially during film formation of the photosensitive material film used when forming patterns such as gates and wirings against the residual stress in the film when forming sensitive material films used when forming patterns such as holes Small residual stress,OrWhen the difference is 2 MPa / μm or more, the effect becomes remarkable. Therefore, the aboveoneIs a gate part in the manufacture of a MOS type semiconductor device,twoThis method is particularly effective when the pattern is a portion other than that.
[0065]
  Chemical vapor depositionWhen the photosensitive film is formed using the (CVD) method, the stress in the film is strongly influenced by the conditions for forming the film. When the film is a film containing a large amount of inorganic material, for example, a polysilane film, the film is more fragile than the organic photosensitive material film.BecomeThere is a tendency for the residual stress reduction in the film to crack during the process.,PeelingSeparationIt is even more important to reduce this.
[0066]
  BookinventionA method for measuring the residual stress in the photosensitive material will be described below. When a thin film such as a photosensitive material is formed on a (100) Si substrate, the curvature radius of the Si wafer changes due to stress in the film of the thin film. This change in curvature radius is measured from the reflection angle of the laser.CanThe
[0067]
  Therefore, it is possible to detect a change in the radius of curvature by measuring the radius of curvature of the Si wafer before and after the formation of the photosensitive film.CanThe The residual stress in the photosensitive film is obtained by a well-known method using this curvature radius change ΔR.
[0068]
  Error factors in the measurement method include measurement temperature, accuracy of the optical system of the apparatus, wafer surface uniformity, film formation conditions, and the like. In particular, it greatly depends on the environment when measuring.
[0069]
【Example】
[Example 1]
  In the process of FIG.ObedienceThus, a thin film 102 is formed by spin-coating a positive cycloolefin-based resin photosensitive material film having a residual stress in the film of 4.8 MPa with a film thickness of 20000 mm on the silicon substrate 101, and the dimension is 0.2 μm. A space pattern 106 was formed. For the exposure, ArF laser (λ = 193 nm) is used as the irradiation light 104, and development is a commercially available alkali development.In liquidFor 1 minute.
[0070]
  The value K of the photosensitive material film is about 2.9, and the absorption coefficient with respect to the exposure wavelength is 0.43 / μm.
[0071]
  When quality evaluation of the obtained pattern was performed on an 8-inch wafer by a defect inspection apparatus, pattern peeling was detected for every 10 sheets.YouHowever, it can be sufficiently put into practical use in the manufacturing process of VLSI. As described above, by using a resist having a small residual stress in the film, pattern peeling can be avoided even if a photosensitive material having a film thickness of about 20000 mm is used.
[0072]
[Example 2]
  By a production process similar to that of Example 1, a chemically amplified positive photosensitive material mainly containing an acrylate polymer at room temperature of 23 ° C. was spin-coated at a thickness of 8615 mm, 12345 mm, 6144 mm, 3825 mm, and a thickness of 525 μm. Each was formed on an inch Si substrate. When the residual stress in the film was measured, it was found that there was a proportional relationship between each film thickness and the residual stress.
[0073]
  Next, various photosensitive materials were respectively formed on a 4-inch Si substrate having a thickness of 525 μm, and the residual stress in the film was measured. The residual stress in the film when converted to a film thickness of 1 μm was 5 MPa for polyvinylphenol, It was 7 MPa for the positive photosensitive material for chemically amplified KrF, 22 MPa for polynorbornene, 14 MPa for PMMA, and 25 MPa for polycycloolefin.
[0074]
  Therefore, the polycycloolefin resin was mixed with 5%, 10%, 15%, and 20% of cholic acid ester as a stress reducing agent, respectively, and the residual stress in the film was measured.
[0075]
  The results are shown in Table 1. The residual stress in the film of the comparative example in which the cholate is not mixed is 31 MPSince it is a / μm, the residual stress in the film can be arbitrarily adjusted by mixing an appropriate amount. Here, it adjusted in the range of 22-8 Mpa / micrometer.
[0076]
[Table 1]

  Pattern formation with a dimension of 0.11 μm was performed using an ArF exposure apparatus (NA 0.6) using a material obtained by mixing 10% cholic acid ester with polycycloolefin resin. The absorption coefficient of the above material is 0.5 / μm.
[0077]
  The value K obtained by K = total number of atoms / (number of carbon atoms−number of oxygen atoms) was 2.9.
[0078]
  When the formed pattern was detected by the defect inspection apparatus in the same manner as in Example 1, peeling was seen at a rate of 0.6 per 100 8-inch wafers. No pattern cracking was observed in 100 sheets. As described above, the effectiveness of applying the low residual stress photosensitive material in the pattern forming method was confirmed.
[0079]
[Example 3]
  A chemically amplified positive photosensitive material based on a polycycloolefin-based resin was spin-coated on a 4-inch Si substrate to form a thin 8400 mm film, and a pattern was formed in the same process as in Example 1. In the coating film forming step, the temperature was increased at a rate of 20 ° C./min, then maintained at 150 ° C. for 120 seconds, and then naturally cooled.
[0080]
  The stress was measured at each temperature, and the results are shown in FIG. It can be seen that the residual stress in the film is relaxed as the temperature increases. In the process of lowering the temperature, the residual stress in the film of the photosensitive material gradually increases. Even in a photosensitive material thin film having a residual stress after film formation of about 20 MPa / μm, when the residual stress in the film during development was 21 MPa / μm, no cracking of the pattern was observed by SEM observation.
[0081]
  In this example, the change in the in-film residual stress after the heat treatment is 5% with respect to the in-film residual stress at the time of film formation, which satisfies the condition of within 10% according to the second invention.
[0082]
[Example 4]
  This embodiment relates to a method of manufacturing a dynamic RAM semiconductor device using the present invention, and will be described with reference to the process diagram of FIG. The following description is intended to show the relationship between the main steps of the manufacturing process of the MOS semiconductor device and the present invention, and therefore does not describe all of the manufacturing steps.
[0083]
  FIG. 2A is a cross-sectional view showing the main part of the MOS semiconductor device finally obtained by this embodiment. The MISFET includes a gate insulating film 201, a gate electrode 202, and source / drain n-type high concentration impurity regions 203, and a plug electrode 204 is formed through the silicon oxide films 201 and 215 on the high concentration impurity regions. Has been.
[0084]
  Further, an electrode wiring 205 is formed on the silicon oxide film. A crown type capacitor 207 is provided on the silicon oxide film 206 and is connected to the high concentration impurity region 203 through a contact hole 216.
[0085]
(Isolation and oxide film formation)
  First, the SiO trench is formed on the silicon substrate 200 by using a well-known shallow trench isolation method.₂An isolation (field oxide film) 208 was formed. Thereafter, a gate oxide film 201 was formed. Note that the composition, structure, film thickness, and the like of the gate oxide film 201 are preferably optimized depending on the device to be applied. (MISFET Formation) The case where the present invention is applied to a MISFET formation step in the manufacture of a semiconductor device will be described with reference to FIGS. 2B and 2C.
[0086]
  As a material for the gate electrode, a composite film of a low-resistance refractory metal film such as tungsten having a thickness of about 100 nm or its silicide film 210 and a polycrystalline silicon film 211 having a thickness of about 100 nm was used.
[0087]
  Further, a silicon nitride film 209 is formed on the gate electrode in order to use a known self-aligned contact. On top of this, a pattern 212 was formed by performing photolithography using a positive photosensitive material having a residual stress in the film of 8 MPa / μm and a thickness of 4000 mm.
[0088]
  The absorption coefficient of the photosensitive material is 0.6 / μm. The value of K determined by K = total number of atoms / (number of carbon atoms−number of oxygen atoms) was 3.0. A negative photosensitive material may be used as the photosensitive material, and the thickness of the photosensitive material varies depending on the underlying structure and etching conditions.
[0089]
  Thereafter, the pattern 212 was transferred to the underlying laminated film by dry etching, thereby forming the gate 213 of the MISFET. Here, the gate length of the MISFET is, for example, 0.13 μm and the polarity is n-channel type, but p-channel type may be used.
[0090]
(Contact hole formation)
  NextThe silicon oxide film 215 on the high-concentration impurity region serving as the source or drain of the MISFET andSilicon nitrideAn opening was formed in the film using a photosensitive material having a larger residual stress in the film than the photosensitive material used for wiring line processing.
[0091]
  About 50nm thickSilicon nitrideA film is deposited by a well-known low pressure chemical vapor deposition method (hereinafter abbreviated as LPCVD method),NextThe silicon oxide film 215 containing boron and phosphorus having a thickness of about 300 nm is well known.ofCVDLawAnd the surface of the silicon oxide film is smoothed by annealing at a temperature of about 800 ° C.
[0092]
  The silicon oxide film is not added with boron or phosphorus, but a silicon oxide film formed by CVD using TEOS gas at about 400 ° C. is used and is flattened by another method such as CMP (Chemical Mechanical Polishing). AlsoCanThe
[0093]
  In this case, a flat silicon oxide film surface is obtained over the entire wafer surface. Furthermore, MISFET punch-through can be prevented by lowering the temperature of the manufacturing process.CanThe Further, the high concentration impurity region 203 in the source / drain region of the MISFETSilicon nitrideIt may be formed using ion implantation after depositing the film. As a result, the lateral direction of the high concentration impurity region can be adjusted.soThis is effective in preventing punch-through of the MISFET.
[0094]
  After the above film formation, lithography was performed using the same method as in Example 1. At this time, a photosensitive material having a residual stress in the film of 12 MPa / μm was used. The silicon oxide film 215 in the opening was etched.
[0095]
  The absorption coefficient of the above material was 0.5 / μm, and the value of K obtained by K = total number of atoms / (number of carbon atoms−number of oxygen atoms) was 3.2. At this time, dry etching of the silicon oxide film 215 is performed.Silicon nitrideThe film is used as an etching stopper, and anisotropicSilicon nitrideBy dry etching ofSilicon nitrideThe film is etched to form a self-aligned opening with respect to the gate electrode and the field oxide film.
[0096]
  NextA polycrystalline silicon film having a thickness of 200 nm to which phosphorus is added at a high concentration is deposited by LPCVD and etched back by anisotropic dry etching to form a plug electrode in the opening. Note that tungsten orTitanium nitrideCan be used to obtain good electrical contactCanThe
[0097]
  Also, when using a refractory metal such as tungsten, for the purpose of preventing reaction with the silicon substrate.Titanium nitrideIt is preferable to provide a barrier metal film such as a lower layer.
[0098]
(Wiring formation)
  Next, a wiring electrode having a thickness of about 100 nm to be the wiring 205 is deposited, and using a photosensitive material having a photosensitive material film thickness of 5000 mm and a residual stress in the film of 7 MPa / μm,HoThe pattern was formed by photolithography. As a material for the wiring electrode, a silicide film of a refractory metal such as tungsten and a composite film of polycrystalline silicon, or a refractory metal such as tungsten is preferably used.CanThe
[0099]
  Next, a silicon oxide film 215 containing boron and phosphorus having a thickness of about 200 nm is deposited by a CVD method and annealed at a temperature of about 800 ° C. to smooth the surface.
[0100]
  Finally, the crown type capacitor 207, the silicon oxide film of the interlayer insulating film, and the aluminum wiring as the metal wiring are formed to complete the semiconductor memory device of the present invention.
[0101]
  As a result of performing the device manufacturing process using the pattern forming method of the present invention, the pattern is removed.SeparationTo form a pattern with less cracksCanIt was. Therefore, it is possible to obtain a dynamic random access memory semiconductor device having an improved yield of 10% or more.CanIt was.
[0102]
  As mentioned above, the example in which the present invention is applied to the basic pattern of the MOS LSI has been described. However, other processes of the LSI and semiconductor devices of other types and materials, such as bipolar LSIs and gallium arsenide semiconductors, are not limited to this example. It can also be applied to optoelectronic elements such as semiconductor lasers. In that case, the material to be processed, the type of photosensitive material, the exposure method, the development method, the etching method, the gas, etc. are changed.Accordingly, the composition and processing conditions of the antireflection material according to the present invention are It is desirable to optimize without departing from the spirit.
[0103]
【The invention's effect】
  As described in detail above, according to the present invention, at least the photosensitive material pattern is cracked and peeled off.SeparationOccursGarlicHaving an improved pattern forming method and a fine structure of 0.2 μm or less,OrThe intended purpose of realizing a method for manufacturing a semiconductor device with a high yield and a low price could be achieved.
[0104]
  That is, the present invention prevents physical destruction of the photosensitive material during the lithography process in the manufacturing of the semiconductor device, and improves the yield of the semiconductor device. This is particularly effective for improving the yield in mass production.
[Brief description of the drawings]
FIG. 1 is a cross-sectional process diagram illustrating a procedure of a pattern forming process.
FIGS. 2A and 2B are cross-sectional views showing a main part structure and a manufacturing process of a semiconductor device according to an embodiment of the present invention;
FIG. 3 is a characteristic diagram showing the relationship between residual stress in a film, pattern cracking, and peeling for explaining the present invention.
FIG. 4 is a characteristic diagram showing a relationship between a difference in residual stress in a photosensitive thin film used for a hole layer and a gate layer and a yield when the present invention is applied to a method for manufacturing a semiconductor device.
FIG. 5 is a characteristic diagram comparing the in-film residual stress before and after heat treatment of a photosensitive thin film.
[Explanation of symbols]
101, 200 ... substrate, 102 ... photosensitive material thin film,
104 ... radiation, 105 ... exposure part,
106: Fine pattern formed, 201: Gate insulating film,
202 ... gate electrode, 203 ... source / drain,
204 ... Plug electrode, 205 ... Electrode wiring,
206, 215 ... silicon oxide film, 207 ... crown type capacitor,
208 ... Field oxide film, 209 ...Silicon nitridefilm,
210 ... tungsten silicide film, 211 ... polycrystalline silicon film,
212 ... photosensitive material pattern, 213 ... MISFET,
216: Plug electrode.

Claims (2)

Forming a thin film of a photosensitive material on a substrate, selectively exposing the thin film to radiation having a wavelength of 10 to 200 nm, and selectively removing the exposed or unexposed area by developing In the fine pattern formation method including, as said photosensitive material, K value calculated | required according to following Formula from the total number of atoms contained in it, the number of carbon atoms, and the number of oxygen atoms is 3.3 or less,
K = total number of atoms / (number of carbon atoms−number of oxygen atoms)
Residual stress in the film after thin film formation is 15 MPa / μm or less, absorption coefficient for radiation is 1 / μm or less ,
The photosensitive material has a cycloolefin resin as a main component,
Further, the photosensitive material, a fine pattern forming method comprising Rukoto such by one or more stress-lowering agent selected from the group consisting of cholate and lithocholic acid ester was added 10 wt% or more. Forming a thin film of a photosensitive material on at least one of an insulating layer and a wiring layer formed on a semiconductor substrate, selectively exposing the thin film, and developing to form a predetermined resist mask pattern A method for manufacturing a semiconductor device comprising: forming a resist mask pattern using the fine pattern forming method according to claim 1 .

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