JP2001144062A - Polishing method - Google Patents
Polishing methodInfo
- Publication number
- JP2001144062A JP2001144062A JP32399599A JP32399599A JP2001144062A JP 2001144062 A JP2001144062 A JP 2001144062A JP 32399599 A JP32399599 A JP 32399599A JP 32399599 A JP32399599 A JP 32399599A JP 2001144062 A JP2001144062 A JP 2001144062A
- Authority
- JP
- Japan
- Prior art keywords
- polishing
- solid abrasive
- abrasive grains
- copper
- polishing liquid
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000005498 polishing Methods 0.000 title claims abstract description 157
- 238000000034 method Methods 0.000 title claims abstract description 34
- 239000007787 solid Substances 0.000 claims abstract description 45
- 239000006061 abrasive grain Substances 0.000 claims abstract description 36
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims abstract description 32
- 229910052802 copper Inorganic materials 0.000 claims abstract description 32
- 239000010949 copper Substances 0.000 claims abstract description 32
- 229910000881 Cu alloy Inorganic materials 0.000 claims abstract description 29
- 239000000758 substrate Substances 0.000 claims abstract description 27
- 239000004744 fabric Substances 0.000 claims abstract description 19
- 239000007788 liquid Substances 0.000 claims description 60
- 229910052751 metal Inorganic materials 0.000 claims description 39
- 239000002184 metal Substances 0.000 claims description 39
- 229910052715 tantalum Inorganic materials 0.000 claims description 11
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 claims description 10
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims description 7
- 239000010936 titanium Substances 0.000 claims description 6
- 229910052719 titanium Inorganic materials 0.000 claims description 5
- 229920002125 Sokalan® Polymers 0.000 claims description 4
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 4
- BJEPYKJPYRNKOW-UHFFFAOYSA-N alpha-hydroxysuccinic acid Natural products OC(=O)C(O)CC(O)=O BJEPYKJPYRNKOW-UHFFFAOYSA-N 0.000 claims description 4
- QRUDEWIWKLJBPS-UHFFFAOYSA-N benzotriazole Chemical compound C1=CC=C2N[N][N]C2=C1 QRUDEWIWKLJBPS-UHFFFAOYSA-N 0.000 claims description 4
- 239000012964 benzotriazole Substances 0.000 claims description 4
- 239000004584 polyacrylic acid Substances 0.000 claims description 4
- 229910052721 tungsten Inorganic materials 0.000 claims description 4
- BJEPYKJPYRNKOW-REOHCLBHSA-N (S)-malic acid Chemical compound OC(=O)[C@@H](O)CC(O)=O BJEPYKJPYRNKOW-REOHCLBHSA-N 0.000 claims description 3
- 239000006185 dispersion Substances 0.000 claims description 3
- 239000005001 laminate film Substances 0.000 claims description 3
- 235000011090 malic acid Nutrition 0.000 claims description 3
- 239000001630 malic acid Substances 0.000 claims description 3
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 claims description 3
- 239000010937 tungsten Substances 0.000 claims description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 3
- 229910045601 alloy Inorganic materials 0.000 claims description 2
- 239000000956 alloy Substances 0.000 claims description 2
- 238000002156 mixing Methods 0.000 claims description 2
- 230000004888 barrier function Effects 0.000 abstract description 28
- 230000003628 erosive effect Effects 0.000 abstract description 11
- 238000007517 polishing process Methods 0.000 abstract 1
- 239000010408 film Substances 0.000 description 45
- 239000010410 layer Substances 0.000 description 33
- 239000003795 chemical substances by application Substances 0.000 description 8
- 230000000694 effects Effects 0.000 description 6
- 239000000463 material Substances 0.000 description 5
- 229910044991 metal oxide Inorganic materials 0.000 description 5
- 150000004706 metal oxides Chemical class 0.000 description 5
- 239000004065 semiconductor Substances 0.000 description 5
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 4
- 230000001681 protective effect Effects 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 3
- 238000009826 distribution Methods 0.000 description 3
- 238000011156 evaluation Methods 0.000 description 3
- 150000004767 nitrides Chemical class 0.000 description 3
- 230000003287 optical effect Effects 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 2
- 239000003153 chemical reaction reagent Substances 0.000 description 2
- 239000004020 conductor Substances 0.000 description 2
- 239000011229 interlayer Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000007800 oxidant agent Substances 0.000 description 2
- 238000007747 plating Methods 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 239000003870 refractory metal Substances 0.000 description 2
- 238000004544 sputter deposition Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 239000010409 thin film Substances 0.000 description 2
- 230000000007 visual effect Effects 0.000 description 2
- 229910000838 Al alloy Inorganic materials 0.000 description 1
- 101000650817 Homo sapiens Semaphorin-4D Proteins 0.000 description 1
- 102100027744 Semaphorin-4D Human genes 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- 239000004115 Sodium Silicate Substances 0.000 description 1
- 229910001362 Ta alloys Inorganic materials 0.000 description 1
- 229910001069 Ti alloy Inorganic materials 0.000 description 1
- NRTOMJZYCJJWKI-UHFFFAOYSA-N Titanium nitride Chemical compound [Ti]#N NRTOMJZYCJJWKI-UHFFFAOYSA-N 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 239000008119 colloidal silica Substances 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000001312 dry etching Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- 238000005187 foaming Methods 0.000 description 1
- 238000007429 general method Methods 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 238000005342 ion exchange Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 239000004745 nonwoven fabric Substances 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 238000000206 photolithography Methods 0.000 description 1
- 238000005268 plasma chemical vapour deposition Methods 0.000 description 1
- 229920002635 polyurethane Polymers 0.000 description 1
- 239000004814 polyurethane Substances 0.000 description 1
- 229920005749 polyurethane resin Polymers 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 229910052814 silicon oxide Inorganic materials 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 description 1
- 229910052911 sodium silicate Inorganic materials 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 150000003482 tantalum compounds Chemical class 0.000 description 1
- MZLGASXMSKOWSE-UHFFFAOYSA-N tantalum nitride Chemical compound [Ta]#N MZLGASXMSKOWSE-UHFFFAOYSA-N 0.000 description 1
- 150000003609 titanium compounds Chemical class 0.000 description 1
Landscapes
- Finish Polishing, Edge Sharpening, And Grinding By Specific Grinding Devices (AREA)
- Internal Circuitry In Semiconductor Integrated Circuit Devices (AREA)
- Weting (AREA)
- Mechanical Treatment Of Semiconductor (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、半導体デバイスの
配線形成工程に用いられる研磨方法に関連し、特に埋め
込み配線の形成工程において使用される研磨方法に関す
る。[0001] 1. Field of the Invention [0002] The present invention relates to a polishing method used in a wiring forming step of a semiconductor device, and more particularly to a polishing method used in a forming step of an embedded wiring.
【０００２】[0002]
【従来の技術】近年、半導体集積回路（以下ＬＳＩと記
す）の高集積化、高性能化に伴って新たな微細加工技術
が開発されている。化学機械研磨（以下ＣＭＰと記す）
法もその一つであり、ＬＳＩ製造工程、特に多層配線形
成工程における層間絶縁膜の平坦化、金属プラグ形成、
埋め込み配線形成において頻繁に利用される技術であ
る。この技術は、例えば米国特許第４９４４８３６号に
開示されている。2. Description of the Related Art In recent years, a new fine processing technology has been developed in accordance with high integration and high performance of a semiconductor integrated circuit (hereinafter, referred to as LSI). Chemical mechanical polishing (hereinafter referred to as CMP)
The method is one of them. For example, in an LSI manufacturing process, particularly, in a multilayer wiring forming process, an interlayer insulating film is flattened, a metal plug is formed,
This is a technique frequently used in the formation of embedded wiring. This technique is disclosed, for example, in US Pat. No. 4,944,836.
【０００３】また、最近はＬＳＩを高性能化するため
に、配線材料として銅合金の利用が試みられている。し
かし、銅合金は従来のアルミニウム合金配線の形成で頻
繁に用いられたドライエッチング法による微細加工が困
難である。そこで、あらかじめ溝を形成してある絶縁膜
上に銅合金薄膜を堆積して埋め込み、溝部以外の銅合金
薄膜をＣＭＰにより除去して埋め込み配線を形成する、
いわゆるダマシン法が主に採用されている。この技術
は、例えば特開平２−２７８８２２号公報に開示されて
いる。Recently, use of a copper alloy as a wiring material has been attempted in order to improve the performance of an LSI. However, it is difficult to finely process a copper alloy by a dry etching method frequently used in forming a conventional aluminum alloy wiring. Therefore, a copper alloy thin film is deposited and buried on an insulating film in which a groove is formed in advance, and a copper alloy thin film other than the groove is removed by CMP to form a buried wiring.
The so-called damascene method is mainly employed. This technique is disclosed in, for example, Japanese Patent Application Laid-Open No. 2-278822.
【０００４】金属のＣＭＰの一般的な方法は、円形の支
持基体（プラテン）上に研磨布（パッド）を貼り付け、
研磨パッド表面を金属用研磨液で浸し、基板の金属膜を
形成した面を押し付けて、その裏面から所定の圧力（以
下研磨圧力と記す）を加えた状態で支持基体を回し、研
磨液と金属膜の凸部との機械的摩擦によって凸部の金属
膜を除去するものである。[0004] A general method of metal CMP is to attach an abrasive cloth (pad) on a circular support base (platen),
The surface of the polishing pad is immersed in a metal-polishing liquid, the surface of the substrate on which the metal film is formed is pressed, and the support base is rotated with a predetermined pressure (hereinafter referred to as polishing pressure) applied from the back surface, and the polishing liquid and metal The metal film on the convex portion is removed by mechanical friction with the convex portion of the film.
【０００５】ＣＭＰに用いられる金属用研磨液は、一般
には酸化剤及び固体砥粒からなっており必要に応じてさ
らに酸化金属溶解剤、保護膜形成剤が添加される。まず
酸化によって金属膜表面を酸化し、その酸化層を固体砥
粒によって削り取るのが基本的なメカニズムと考えられ
ている。凹部の金属表面の酸化層は研磨パッドにあまり
触れず、固体砥粒による削り取りの効果が及ばないの
で、ＣＭＰの進行とともに凸部の金属層が除去されて基
体表面は平坦化される。この詳細についてはジャ−ナル
・オブ・エレクトロケミカルソサエティ誌（Journal of
ElectrochemicalSociety）の第１３８巻１１号（１９
９１年発行）の３４６０〜３４６４頁に開示されてい
る。[0005] The metal polishing liquid used for CMP generally comprises an oxidizing agent and solid abrasive grains, and if necessary, a metal oxide dissolving agent and a protective film forming agent are further added. It is considered that the basic mechanism is to first oxidize the surface of the metal film by oxidation and to scrape off the oxidized layer with solid abrasive grains. The oxide layer on the metal surface of the concave portion does not substantially touch the polishing pad, and the effect of the shaving by the solid abrasive grains does not reach. Therefore, as the CMP proceeds, the metal layer on the convex portion is removed and the substrate surface is flattened. See the Journal of Electrochemical Society (Journal of
Vol. 138, No. 11 (19)
1991), pages 3460-3364.
【０００６】ＣＭＰによる研磨速度を高める方法として
酸化金属溶解剤を添加することが有効とされている。固
体砥粒によって削り取られた金属酸化物の粒を研磨液に
溶解させてしまうと固体砥粒による削り取りの効果が増
すためであると解釈できる。但し、凹部の金属膜表面の
酸化層も溶解（以下エッチングと記す）されて金属膜表
面が露出すると、酸化剤によって金属膜表面がさらに酸
化され、これが繰り返されると凹部の金属膜のエッチン
グが進行してしまい、平坦化効果が損なわれることが懸
念される。これを防ぐためにさらに保護膜形成剤が添加
される。酸化金属溶解剤と保護膜形成剤の効果のバラン
スを取ることが重要であり、凹部の金属膜表面の酸化層
はあまりエッチングされず、削り取られた酸化層の粒が
効率良く溶解されＣＭＰによる研磨速度が大きいことが
望ましい。As a method of increasing the polishing rate by CMP, it is effective to add a metal oxide dissolving agent. It can be interpreted that dissolving the metal oxide particles removed by the solid abrasive grains in the polishing liquid increases the effect of the solid abrasive grains. However, when the oxide layer on the surface of the metal film in the recess is also dissolved (hereinafter referred to as etching) and the surface of the metal film is exposed, the surface of the metal film is further oxidized by the oxidizing agent. It is feared that the flattening effect is impaired. In order to prevent this, a protective film forming agent is further added. It is important to balance the effects of the metal oxide dissolving agent and the protective film forming agent. The oxide layer on the surface of the metal film in the concave portion is not etched so much, the particles of the cut oxide layer are efficiently dissolved, and polishing by CMP is performed. High speed is desirable.
【０００７】このように酸化金属溶解剤と保護膜形成剤
を添加して化学反応の効果を加えることにより、ＣＭＰ
速度（ＣＭＰによる研磨速度）が向上すると共に、ＣＭ
Ｐされる金属層表面の損傷（ダメ−ジ）も低減される効
果が得られる。As described above, by adding the metal oxide dissolving agent and the protective film forming agent to add the effect of the chemical reaction, the CMP
The speed (polishing speed by CMP) is improved and the CM
The effect of reducing the damage (damage) on the surface of the metal layer to be P is obtained.
【０００８】一方、配線の銅或いは銅合金等の下層に
は、層間絶縁膜中への銅拡散防止のためにバリア層とし
て、チタンやチタン合金及び窒化チタン等のチタン化合
物、タンタルやタンタル合金及び窒化タンタル等のタン
タル化合物等が形成される。これらの材料は導体である
ため、銅或いは銅合金を埋め込む配線部分以外では、露
出したバリア層をＣＭＰにより取り除く必要がある。し
かし、これらのバリア層は、銅或いは銅合金に比べ硬度
が高いために、銅或いは銅合金用の研磨材料の組み合わ
せでは十分なＣＭＰ速度が得られない場合が多い。そこ
で、銅或いは銅合金を研磨する第１工程と、バリア層を
研磨する第２工程からなる２段研磨方法が検討されてい
る。またバリア層材料は銅或いは銅合金に比べて抵抗率
が大きいため、なるべく薄く形成することが求められて
おり、一般的にその膜厚は５０ｎｍ以下とされている。On the other hand, under the wiring such as copper or copper alloy, as a barrier layer for preventing copper diffusion into the interlayer insulating film, titanium compounds such as titanium, titanium alloy and titanium nitride, tantalum and tantalum alloy and A tantalum compound such as tantalum nitride is formed. Since these materials are conductors, it is necessary to remove the exposed barrier layer by CMP except for the wiring portion where copper or a copper alloy is embedded. However, since these barrier layers have higher hardness than copper or copper alloy, a combination of polishing materials for copper or copper alloy often cannot provide a sufficient CMP rate. Therefore, a two-step polishing method including a first step of polishing copper or a copper alloy and a second step of polishing a barrier layer has been studied. Further, since the barrier layer material has a higher resistivity than copper or a copper alloy, it is required to be formed as thin as possible, and the film thickness is generally set to 50 nm or less.
【０００９】銅或いは銅合金を研磨する第１工程と、バ
リア層を研磨する第２工程からなる２段研磨方法では、
被研磨膜の硬度や化学的性質が異なるために、研磨液の
ｐＨ、固体砥粒及び添加剤等の組成物について、異なる
性質のものが検討されている。In a two-stage polishing method comprising a first step of polishing copper or a copper alloy and a second step of polishing a barrier layer,
Since the hardness and chemical properties of the films to be polished are different, compositions having different properties are being studied for the pH of the polishing liquid, solid abrasive grains, additives and the like.
【００１０】[0010]
【発明が解決しようとする課題】従来の固体砥粒を含む
研磨液を用いて2段研磨によりＣＭＰによる埋め込み配
線形成を行う場合には、銅或いは銅合金用の研磨液を用
い銅或いは銅合金層を研磨した後、バリヤ層用の研磨液
を用いてバリア層の研磨を行い下地絶縁膜が露出するま
で研磨を行う。金属積層膜の最上層に形成された銅或い
は銅合金は、膜形成時の膜厚の不均一性および研磨速度
の不均一性等により、研磨終了時間が同一基板内で異な
っている。このため研磨が早く進んだ部分では下地のバ
リヤ層も研磨されてバリヤ層の膜厚が薄くなるという問
題があった。第１段目の銅或いは銅合金研磨時にバリヤ
層の薄い部分が生じると、続く第２段目のバリヤ層の研
磨でバリヤ層の研磨時間に分布が生じ、下地の絶縁膜が
研磨され結果として配線膜厚の薄い部分（エロージョ
ン）が発生するという問題があった。本発明は、銅或い
は銅合金とバリア層との研磨速度比を大きくして、高平
坦化、エロージョン量低減を可能とし、信頼性の高い金
属膜の埋め込みパタ−ン形成を可能とする研磨方法を提
供するものである。When the embedded wiring is formed by CMP using two-stage polishing with a conventional polishing liquid containing solid abrasive grains, a polishing liquid for copper or copper alloy is used. After the layer is polished, the barrier layer is polished by using a polishing liquid for the barrier layer, and the polishing is performed until the underlying insulating film is exposed. The copper or copper alloy formed on the uppermost layer of the metal laminated film has a different polishing end time within the same substrate due to non-uniformity of the film thickness at the time of film formation and non-uniformity of the polishing rate. For this reason, there has been a problem that the underlying barrier layer is also polished in the portion where polishing has progressed quickly, and the thickness of the barrier layer is reduced. If a thin portion of the barrier layer is formed during the first-stage copper or copper alloy polishing, the polishing of the barrier layer will have a distribution in the subsequent polishing of the second-stage barrier layer, and the underlying insulating film will be polished as a result. There is a problem that a portion (erosion) where the wiring film thickness is small occurs. The present invention increases the polishing rate ratio between copper or a copper alloy and a barrier layer, enables high flatness, reduces the amount of erosion, and enables formation of a highly reliable buried pattern of a metal film. Is provided.
【００１１】[0011]
【課題を解決するための手段】本発明は、表面に凹凸の
有る金属積層膜を有する基板を支持基体に貼り付けた研
磨布に押し付け、研磨布上に研磨液を供給しながら前記
基板と前記支持基体とを相対的に動かすことにより、前
記金属積層膜を研磨し前記金属膜表面の凹凸を平坦化す
る研磨方法において、前記金属積層膜の1層目の研磨に
前記研磨液に固体砥粒を含まない研磨液を使用し、続く
2層目の研磨に固体砥粒を含む研磨液を使用することを
特徴とする。本発明の研磨方法は、金属積層膜の1層目
が銅或いは銅合金であり、2層目がチタン、タンタル、
タングステン及びそれらの合金（含窒化物）の何れかを
含む場合に有効である。固体砥粒を含む研磨液は、固体
砥粒を含まない研磨液に固体砥粒分散液を、研磨布上ま
たは研磨布に供給する直前に混合することにより作製さ
れることが簡便で好ましい。固体砥粒を含まない研磨液
は、過酸化水素、リンゴ酸、ベンゾトリアゾール、ポリ
アクリル酸及び水を含む研磨液であることが好ましい。
本発明では埋め込み配線形成のための研磨方法として、
銅或いは銅合金の研磨にはバリヤメタルの研磨速度の小
さい固体砥粒を含まない研磨液を使用し、バリヤ層の研
磨には従来から用いられている固体砥粒を含む研磨液を
使用して研磨する。これにより、銅或いは銅合金の研磨
速度の面内分布等があった場合でも、バリヤメタルが早
く露出した部分でもバリヤメタルの研磨が進まないた
め、銅或いは銅合金を選択的に研磨することが可能にな
り、基板の面内均一性を向上させることができる。この
ため引き続いてバリヤメタルを研磨した後の均一性が向
上し、エロージョン等による配線膜厚の低減を防止する
ことができるため、信頼性を向上させることができる。According to the present invention, a substrate having a metal laminated film having an uneven surface is pressed against a polishing cloth adhered to a supporting base, and the substrate is mixed with the polishing liquid while supplying a polishing liquid onto the polishing cloth. In a polishing method for polishing the metal laminate film and flattening irregularities on the surface of the metal film by relatively moving a support base, solid abrasive grains are added to the polishing liquid for polishing the first layer of the metal laminate film. Using a polishing liquid that does not contain
It is characterized in that a polishing liquid containing solid abrasive grains is used for polishing the second layer. In the polishing method of the present invention, the first layer of the metal laminated film is copper or a copper alloy, and the second layer is titanium, tantalum,
It is effective when it contains any of tungsten and their alloys (nitrides). The polishing liquid containing the solid abrasive grains is preferably simply and preferably prepared by mixing the solid abrasive dispersion liquid with the polishing liquid not containing the solid abrasive grains immediately before or on the polishing cloth. The polishing liquid containing no solid abrasive grains is preferably a polishing liquid containing hydrogen peroxide, malic acid, benzotriazole, polyacrylic acid and water.
In the present invention, as a polishing method for forming embedded wiring,
For polishing copper or copper alloy, use a polishing liquid that does not contain solid abrasive grains with a low polishing rate for barrier metal, and use a polishing liquid that contains conventionally used solid abrasive grains for polishing the barrier layer. I do. As a result, even if there is an in-plane distribution of the polishing rate of copper or copper alloy, etc., the polishing of the barrier metal does not proceed even in the portion where the barrier metal is exposed early, so that copper or copper alloy can be selectively polished. Thus, the in-plane uniformity of the substrate can be improved. For this reason, the uniformity after the subsequent polishing of the barrier metal is improved, and a reduction in the wiring film thickness due to erosion or the like can be prevented, so that reliability can be improved.
【００１２】[0012]
【発明の実施の形態】本発明においては、表面に凹部を
有する絶縁膜を形成した基板上に、Ｔａ（タンタル）、
Ｔｉ（チタン）、Ｗ（タングステン）等の高融点金属膜
またはそれらの窒化物膜、続いて銅或いは銅合金膜を形
成・充填する。この基板を本発明による研磨方法でＣＭ
Ｐすると、基板の凸部の金属膜が選択的にＣＭＰされ
て、凹部に金属膜が残されて所望の導体パタ−ンが得ら
れる。本発明の研磨方法は、支持基体に貼り付けた研磨
布上に前記の研磨液を供給しながら、被研磨膜を有する
基板を研磨布に押圧した状態で支持基体と基板を相対的
に動かすことによって被研磨膜を研磨する研磨方法であ
る。研磨する装置としては、半導体基板を保持するホル
ダと研磨布（パッド）を貼り付けた定盤を有する一般的
な研磨装置が使用できる。研磨布としては、一般的な不
織布、発泡ポリウレタン、多孔質フッ素樹脂などが使用
でき、特に制限がない。銅或いは銅合金の研磨には、固
体砥粒を含まない研磨液を使用する。ここで固体砥粒を
含まない研磨液とは固体砥粒濃度が１重量％未満の研磨
液であり、好ましくは０．１重量％未満の研磨液であ
る。Ｔａ、Ｔｉ、Ｗ等の高融点金属またはそれらの窒化
物は硬度の大きい材料であるため固体砥粒を含まない研
磨液ではほとんど研磨されない。このため銅或いは銅合
金の研磨速度に分布があり、銅或いは銅合金の研磨速度
の早い部分でバリヤメタルが早く露出しても、バリヤメ
タルで研磨が停止するため銅或いは銅合金のみ選択的に
研磨することができる。このため均一性を向上させるこ
とが可能となる。一方、固体砥粒入りの研磨液で継続し
て全ての銅或いは銅合金が研磨除去されるまで研磨する
と、固体砥粒による研磨作用が大きいためバリヤメタル
も研磨されてしまう。このバリヤメタルが一部研磨され
た状態で、バリヤメタル用の研磨液で2段目の研磨を行
うと、バリヤメタルの下地層であるシリカ膜も研磨さ
れ、配線深さの小さい部分が生じ、配線抵抗の増加や断
線など信頼性の低下を生じる。この傾向は特に配線密度
が高い部分で顕著である。固体砥粒を含まない研磨液か
ら固体砥粒を含む研磨液への転換は研磨時間または、支
持基体回転のトルク変動をモニターすることにより可能
である。研磨液の切り替えは、固体砥粒入り、固体砥粒
無の２種類の研磨液を準備し、逐次切り替えて供給して
もよいし、固体砥粒無しの研磨液と、固体砥粒の分散液
を準備し、２種のポンプで別々に供給し、研磨布上で混
合すること、または研磨布上に供給する前に混合し供給
することが可能である。この方法では固体砥粒の添加量
が任意に制御することが可能である。研磨条件に制限は
ないが、定盤の回転速度は基板が飛び出さないように２
００ｒｐｍ以下の低回転が好ましい。被研磨膜を有する
半導体基板の研磨布への押し付け圧力は、９．８〜４９
ＫＰａ（１００〜５００ｇｆ／ｃｍ2）であることが好
ましく、ＣＭＰ速度のウエハ面内均一性及びパターンの
平坦性を満足するためには、１４．７〜３９．２ＫＰａ
（１５０〜４００ｇｆ／ｃｍ2）であることがより好ま
しい。研磨している間、研磨布には研磨液をポンプ等で
連続的に供給する。この供給量に制限はないが、研磨布
の表面が常に研磨液で覆われていることが好ましい。固
体砥粒を含まない研磨液としては、スループットを向上
させるため、銅及び銅合金の研磨速度が大きいことが望
ましく、過酸化水素、リンゴ酸、ベンゾトリアゾール、
ポリアクリル酸を含む研磨液であることが好ましい。本
研磨液は固体砥粒を含まなくても１５０ｎｍ／ｍｉｎ以
上の研磨速度が得られる。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, Ta (tantalum), Ta (tantalum),
A refractory metal film such as Ti (titanium) and W (tungsten) or a nitride film thereof, and subsequently a copper or copper alloy film are formed and filled. The substrate is subjected to CM by the polishing method according to the present invention.
When P, the metal film in the convex portion of the substrate is selectively CMPed, leaving the metal film in the concave portion to obtain a desired conductor pattern. In the polishing method of the present invention, the substrate having a film to be polished is relatively moved while the substrate having the film to be polished is pressed against the polishing cloth while the polishing liquid is supplied onto the polishing cloth attached to the supporting substrate. This is a polishing method for polishing a film to be polished by the above method. As a polishing apparatus, a general polishing apparatus having a holder for holding a semiconductor substrate and a surface plate to which a polishing cloth (pad) is attached can be used. As the polishing cloth, general nonwoven fabric, foamed polyurethane, porous fluororesin and the like can be used, and there is no particular limitation. For polishing copper or a copper alloy, a polishing liquid containing no solid abrasive grains is used. Here, the polishing liquid containing no solid abrasive is a polishing liquid having a solid abrasive concentration of less than 1% by weight, preferably a polishing liquid having a concentration of less than 0.1% by weight. Refractory metals such as Ta, Ti, W and the like or nitrides thereof are materials having high hardness and are hardly polished by a polishing liquid containing no solid abrasive grains. For this reason, there is a distribution in the polishing rate of copper or copper alloy, and even if the barrier metal is exposed early in a portion where the polishing rate of copper or copper alloy is high, polishing stops at the barrier metal, so that only copper or copper alloy is selectively polished. be able to. For this reason, the uniformity can be improved. On the other hand, if the polishing is continuously performed with the polishing liquid containing the solid abrasive grains until all the copper or copper alloy is polished and removed, the barrier metal is polished because the solid abrasive grains have a large polishing action. When the barrier metal is partially polished and the second polishing step is performed with a polishing liquid for the barrier metal, the silica film which is a base layer of the barrier metal is also polished, and a portion having a small wiring depth is generated, and the wiring resistance is reduced. The reliability may decrease such as increase or disconnection. This tendency is particularly remarkable in a portion where the wiring density is high. The conversion from the polishing liquid not containing the solid abrasive grains to the polishing liquid containing the solid abrasive grains can be performed by monitoring the polishing time or the fluctuation of the torque of the rotation of the supporting substrate. For the switching of the polishing liquid, two types of polishing liquids containing solid abrasive grains and without solid abrasive grains may be prepared and sequentially supplied and supplied, or a polishing liquid without solid abrasive grains and a dispersion liquid of solid abrasive grains Can be supplied separately by two types of pumps and mixed on a polishing cloth, or mixed and supplied before supplying on a polishing cloth. In this method, the amount of solid abrasive added can be arbitrarily controlled. The polishing conditions are not limited, but the rotation speed of the platen should be 2 so that the substrate does not pop out.
A low rotation of not more than 00 rpm is preferred. The pressing pressure of the semiconductor substrate having the film to be polished against the polishing cloth is 9.8 to 49.
KPa (100 to 500 gf / cm 2 ). In order to satisfy the uniformity of the CMP rate in the wafer surface and the flatness of the pattern, 14.7 to 39.2 KPa is required.
(150 to 400 gf / cm 2 ). During polishing, a polishing liquid is continuously supplied to the polishing cloth by a pump or the like. The supply amount is not limited, but it is preferable that the surface of the polishing pad is always covered with the polishing liquid. As a polishing liquid containing no solid abrasive grains, in order to improve the throughput, it is desirable that the polishing rate of copper and copper alloy is high, hydrogen peroxide, malic acid, benzotriazole,
The polishing liquid preferably contains polyacrylic acid. This polishing liquid can obtain a polishing rate of 150 nm / min or more even without containing solid abrasive grains.
【００１３】[0013]
【実施例】以下、実施例により本発明を具体的に説明す
る。本発明はこれらの実施例により限定されるものでは
ない。 （基板の作製）シリコンウエハーにプラズマＣＶＤ法で
酸化シリコン膜を８００ｎｍ形成し、フォトリソグラフ
ィー法で幅４．５μｍ、溝深さ８００ｎｍの凹部からな
る埋め込み配線部分と幅０．５μｍの凸部からなるスペ
ース部を交互に形成したエロージョン評価部と、幅１０
０μｍ、溝深さ８００ｎｍの凹部からなる埋め込み配線
形成部分と幅１００μｍの凸部からなるスペース部を交
互に形成したディッシング評価部を形成した。次にスパ
ッタ法でバリヤメタルとしてタンタル膜を５０ｎｍ形成
し、続いてメッキ膜のシード層としてスパッタ法で銅を
１００ｎｍ、メッキ法で銅を１４００ｎｍ形成し、凹凸
を持つ絶縁膜上にタンタル、銅の２層膜をもつ半導体基
板を作製した。The present invention will be described below in detail with reference to examples. The present invention is not limited by these examples. (Preparation of Substrate) A silicon oxide film is formed on a silicon wafer to a thickness of 800 nm by a plasma CVD method, and a buried wiring portion consisting of a concave portion having a width of 4.5 μm and a groove depth of 800 nm is formed by photolithography and a convex portion having a width of 0.5 μm. An erosion evaluation section in which spaces are alternately formed, and a width of 10
A dishing evaluation portion was formed in which a buried wiring forming portion formed of a concave portion having a depth of 800 nm and a space portion formed of a convex portion having a width of 100 μm were alternately formed. Next, a tantalum film is formed to a thickness of 50 nm as a barrier metal by a sputtering method, subsequently, 100 nm of copper is formed by a sputtering method and 1400 nm of copper is formed by a plating method as a seed layer of a plating film. A semiconductor substrate having a layer film was manufactured.
【００１４】（研磨液の作製）ＤＬ−リンゴ酸（試薬特
級）０．１５重量部に水７０重量部を加えて溶解し、こ
れにベンゾトリアゾール０．２重量部、分子量１５００
０のポリアクリル酸０．０５重量部を加えた。最後に過
酸化水素水（試薬特級、３０重量％水溶液）３３．２重
量部を加えて得られたものを固体砥粒を含まない研磨液
Ａとした。珪酸ナトリウムのイオン交換法で作製した固
体砥粒濃度４０重量％、平均粒径８０ｎｍのコロイダル
シリカ懸濁液を研磨液Ｂとした。(Preparation of Polishing Solution) To 0.15 parts by weight of DL-malic acid (special grade reagent), 70 parts by weight of water were added and dissolved, and 0.2 parts by weight of benzotriazole and a molecular weight of 1500 were added.
0 part by weight of polyacrylic acid was added. Finally, 33.2 parts by weight of a hydrogen peroxide solution (special grade of reagent, 30% by weight aqueous solution) was added to obtain a polishing liquid A containing no solid abrasive grains. A polishing liquid B was a colloidal silica suspension having a solid abrasive concentration of 40% by weight and an average particle diameter of 80 nm produced by a sodium silicate ion exchange method.
【００１５】（研磨条件）研磨布に独立気泡を持つ発泡
ポリウレタン樹脂を使用し、研磨圧力：２０．６ＫＰａ
（２１０ｇ／ｃｍ2）、基板と支持基体との相対速度：
３６ｍ／ｍｉｎで研磨を行った。研磨液は研磨液Ａを９
０ｍｌ／ｍｉｎで供給し、７分３０秒研磨を行い、銅膜
の研磨を行った。続いて固体砥粒入り研磨液Ｂを１０ｍ
ｌ／ｍｉｎ別の配管で供給し、パッドへ供給直前に研磨
液Ａに混合し固体砥粒濃度４重量％の研磨液にした。こ
の固体砥粒を含む研磨液で１分間研磨を行いタンタル膜
の研磨を行った。 （研磨品の評価）ＣＭＰ後の基板の目視および光学顕微
鏡による表面観察および触針式段差計によるディッシン
グ及びエロ−ジョン量の評価を行った。目視及び光学顕
微鏡により表面観察の結果、銅およびタンタル膜は残り
なく完全に研磨されていることが分かった。触針式段差
計でディッシング及びエロ−ジョンを測定したところ、
エロージョンは、４．５／０．５μｍライン／スペース
部で１０ｎｍ、ディッシングは１００／１００μｍライ
ン／スペース部で３０ｎｍであった。(Polishing conditions) A foaming polyurethane resin having closed cells was used for the polishing cloth, and the polishing pressure was 20.6 KPa.
(210 g / cm 2 ), relative speed between substrate and supporting substrate:
Polishing was performed at 36 m / min. Polishing liquid A is 9
The slurry was supplied at 0 ml / min, polished for 7 minutes 30 seconds, and polished the copper film. Subsequently, 10 m of polishing liquid B containing solid abrasive grains is applied.
1 / min, the mixture was supplied through a separate pipe, and was mixed with the polishing liquid A immediately before the supply to the pad to obtain a polishing liquid having a solid abrasive concentration of 4% by weight. The tantalum film was polished by polishing for 1 minute with the polishing liquid containing the solid abrasive grains. (Evaluation of Polished Product) The substrate after CMP was visually observed, the surface was observed with an optical microscope, and the amount of dishing and erosion was evaluated with a stylus-type profilometer. As a result of visual observation and surface observation by an optical microscope, it was found that the copper and tantalum films were completely polished without any remaining. When dishing and erosion were measured with a stylus step meter,
The erosion was 10 nm at the 4.5 / 0.5 μm line / space part, and the dishing was 30 nm at the 100/100 μm line / space part.
【００１６】（比較例）上記の実施例において研磨液は
研磨液Ａを９０ｍｌ／ｍｉｎ、固体砥粒入り研磨液Ｂを
１０ｍｌ／ｍｉｎ別々のポンプで供給し、研磨布へ供給
直前に混合し固体砥粒濃度４重量％の研磨液にし、この
研磨液で６分間研磨を行い、銅およびタンタルを連続で
研磨した以外は実施例と同様に研磨を行った。目視及び
光学顕微鏡により表面観察を行った結果、銅およびタン
タルは残りなく完全に研磨されていた。触針式段差計で
エロ−ジョン及びディッシングを測定したところ、エロ
ージョンは４．５／０．５μｍライン／スペース部で１
１０ｎｍ、ディシングは１００／１００μｍライン／ス
ペース部で１００ｎｍであった。(Comparative Example) In the above embodiment, the polishing liquid A was supplied at 90 ml / min and the polishing liquid B containing solid abrasive grains was supplied at 10 ml / min by separate pumps. Polishing was performed in the same manner as in Example except that a polishing liquid having an abrasive concentration of 4% by weight was used, and polishing was performed for 6 minutes with this polishing liquid, and copper and tantalum were continuously polished. As a result of visual observation and surface observation by an optical microscope, copper and tantalum were completely polished without any residue. When erosion and dishing were measured using a stylus-type step meter, erosion was 1 at 4.5 / 0.5 μm line / space.
10 nm, and the dishing was 100 nm in a 100/100 μm line / space portion.
【００１７】本発明の研磨方法によれば、エロージョン
を低下させることが可能になることが分かる。またディ
シング特性も併せて改善されており、信頼性の高い埋め
込み配線形成が可能であることが分かる。It can be seen that according to the polishing method of the present invention, erosion can be reduced. In addition, the dishing characteristics are also improved, and it can be seen that highly reliable embedded wiring can be formed.
【００１８】[0018]
【発明の効果】本発明の研磨方法は、銅或いは銅合金層
の研磨に研磨固体砥粒を含まない研磨液を使用すること
によりバリヤメタル研磨速度を低下させ、エロージョン
を生じることなく銅或いは銅合金層の均一な研磨を達成
し、信頼性の高い埋め込み配線パタ−ンを形成すること
ができる。According to the polishing method of the present invention, the polishing rate of the barrier metal is reduced by using a polishing liquid which does not contain abrasive solid abrasive grains for polishing the copper or copper alloy layer. A uniform polishing of the layer can be achieved, and a highly reliable embedded wiring pattern can be formed.
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.7 識別記号 ＦＩ テーマコート゛(参考） Ｈ０１Ｌ 21/306 Ｈ０１Ｌ 21/306 Ｆ Ｍ (72)発明者 内田 剛 茨城県つくば市和台48 日立化成工業株式 会社総合研究所内 (72)発明者 寺崎 裕樹 茨城県つくば市和台48 日立化成工業株式 会社総合研究所内 (72)発明者 五十嵐 明子 茨城県つくば市和台48 日立化成工業株式 会社総合研究所内 Ｆターム(参考） 3C058 AA07 AC01 AC04 BA02 BA09 CB02 DA17 5F043 AA22 AA26 BB15 BB18 DD16 EE08 GG02 ──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. 7 Identification symbol FI Theme coat ゛ (Reference) H01L 21/306 H01L 21/306 FM (72) Inventor Go Uchida 48 Wadai, Tsukuba, Ibaraki Prefecture Hitachi Chemical Co., Ltd. (72) Inventor Hiroki Terasaki 48 Wadai, Tsukuba, Ibaraki Prefecture Hitachi Chemical Co., Ltd. (72) Inventor Akiko Igarashi 48 Wadai, Tsukuba, Ibaraki Prefecture F within Hitachi Chemical Co., Ltd. Terms (reference) 3C058 AA07 AC01 AC04 BA02 BA09 CB02 DA17 5F043 AA22 AA26 BB15 BB18 DD16 EE08 GG02
Claims (4)
板を、支持基体に貼り付けた研磨布に押し付け、研磨布
上に研磨液を供給しながら前記基板と前記支持基体とを
相対的に動かすことにより、前記金属積層膜を研磨し表
面の凹凸を平坦化する研磨方法において、前記金属積層
膜の1層目の研磨に前記研磨液に固体砥粒を含まない研
磨液を使用し、続く2層目の研磨に固体砥粒を含む研磨
液を使用することを特徴とする研磨方法。1. A substrate having a metal laminate film having irregularities on its surface is pressed against a polishing cloth attached to a supporting substrate, and the substrate and the supporting substrate are relatively moved while supplying a polishing liquid onto the polishing cloth. By moving, in the polishing method for polishing the metal laminated film and flattening the surface irregularities, using a polishing liquid containing no solid abrasive in the polishing liquid for polishing the first layer of the metal laminated film, followed by A polishing method characterized by using a polishing liquid containing solid abrasive grains for polishing the second layer.
金であり、2層目がチタン、タンタル、タングステン及
びそれらの合金の何れかを含むことを特徴とする請求項
１に記載の研磨方法。2. The method according to claim 1, wherein the first layer of the metal laminated film is made of copper or a copper alloy, and the second layer contains any of titanium, tantalum, tungsten, and alloys thereof. Polishing method.
砥粒を含まない研磨液に固体砥粒分散液を、研磨布上ま
たは研磨布に供給する直前に混合することにより作製さ
れることを特徴とする請求項１または請求項２に記載の
研磨方法。3. A polishing liquid containing the solid abrasive grains is prepared by mixing a solid abrasive dispersion liquid with a polishing liquid not containing the solid abrasive grains just before supplying it onto a polishing cloth or to a polishing cloth. The polishing method according to claim 1 or 2, wherein
素、リンゴ酸、ベンゾトリアゾール、ポリアクリル酸及
び水を含むことを特徴とする請求項1ないし請求項３の
いずれかに記載の研磨方法。4. The polishing liquid according to claim 1, wherein the polishing liquid containing no solid abrasive contains hydrogen peroxide, malic acid, benzotriazole, polyacrylic acid and water. Polishing method.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP32399599A JP2001144062A (en) | 1999-11-15 | 1999-11-15 | Polishing method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP32399599A JP2001144062A (en) | 1999-11-15 | 1999-11-15 | Polishing method |
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| Publication Number | Publication Date |
|---|---|
| JP2001144062A true JP2001144062A (en) | 2001-05-25 |
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| Application Number | Title | Priority Date | Filing Date |
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| JP32399599A Pending JP2001144062A (en) | 1999-11-15 | 1999-11-15 | Polishing method |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001185515A (en) * | 1999-12-27 | 2001-07-06 | Hitachi Ltd | Polishing method, wire forming method, method for manufacturing semiconductor device and semiconductor integrated circuit device |
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1999
- 1999-11-15 JP JP32399599A patent/JP2001144062A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001185515A (en) * | 1999-12-27 | 2001-07-06 | Hitachi Ltd | Polishing method, wire forming method, method for manufacturing semiconductor device and semiconductor integrated circuit device |
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