JP3736249B2 - Chemical mechanical polishing aqueous dispersion used in the manufacture of semiconductor devices - Google Patents

Description

【００４０】
【表２】

【００４１】
表１の結果によれば、マレイン酸カリウムが１〜３部、過酸化水素が０．１〜３部混合された実施例１〜９の水系分散体では、銅膜とタンタル膜及び／又は窒化タンタル膜との研磨速度の比（R_Cu／R_BM）、並びに銅膜と絶縁体との研磨速度の比（R_Cu／R_In）は、いずれも０．５〜２の範囲内であった。特に研磨剤に複合粒子、又は複合粒子とヒュームドシリカの混合物を用いた実施例４〜６は、 R_Cu／R_BM及びR_Cu／R_inが０．８〜１．２の範囲にあり、又銅膜及び絶縁膜のスクラッチが非常に少なく、充分に平坦化された精度の高い仕上げ面が得られうることが示された。
【００４２】
一方、表２の結果によれば、比較例１〜５では、銅膜とタンタル膜及び／又は窒化タンタル膜との研磨速度の比（R_Cu／R_BM）、並びに銅膜と絶縁体との研磨速度の比（R_Cu／R_In）は、非常に大きいか又は非常に小さい値となり、平坦化が不十分な仕上げ面になることが示された。
また、 R_Cu／R_BM＝１００の１段目用水系分散体を用いた比較例６では、銅膜の研磨速度R_Cuは大きいものの、銅膜とタンタル膜及び／又は窒化タンタル膜との研磨速度の比（R_Cu／R_BM）、並びに銅膜と絶縁体との研磨速度の比（R_Cu／R_In）は小さく、平坦化が不十分な仕上げ面しか得られないことが示された。
【００４３】
実施例１０
シリコンからなる基板表面に、深さ１μｍで５、１０、２５、５０、７５、及び１００μｍの幅を有する溝で形成されたパターンを備える絶縁膜を積層した。次いで、絶縁膜の表面に３００ÅのＴａＮ膜を形成し、その後銅をＴａＮ膜で覆われた溝内にスパッタリング及びめっきにより１．３μｍ堆積し、ウェハーを作製した。
研磨装置としてラップマスターＳＦＴ株式会社製の型式「ＬＧＰ−５１０」を使用し、上記で作製したウェハーを以下の条件で２段階研磨した。ただし１段階目の研磨においては、水系分散体としてヒュームドシリカ系水系分散体（ R_Cu／R_BM＝３０）を使用して３分間研磨し、その後２段階目の研磨として、実施例５で使用したものと同様の水系分散体を用いて、残存の銅とＴａＮが完全に除去されるまで研磨した。
テーブル回転数；５０ｒｐｍ、ヘッド回転数；５０ｒｐｍ、研磨圧力；３００ｇ／ｃｍ²、水系分散体供給速度；１００ｍｌ／分、研磨パッド；ロデール・ニッタ株式会社製、品番ＩＣ１０００／ＳＵＢＡ４００の２層構造
研磨終了後、表面粗さ計（ＫＬＡ−Ｔｅｎｃｏｒ社製、形式「Ｐ−１０」）を用いて１００μｍ幅の銅配線におけるディッシングを測定したところ、４５０Åであった。
【００４４】
実施例１１
２段階目の研磨用の水系分散体として、実施例６で使用のものと同様の水系分散体を使用した他は、実施例１０と同様に２段階研磨し、１００μｍ銅配線におけるディッシングを測定した。
研磨終了後の１００μｍ銅配線におけるディッシングは、４７０Åであった。
【００４５】
比較例７
２段階目の研磨用の水系分散体として、比較例３で使用のものと同様の水系分散体を使用した他は、実施例１０と同様に２段階研磨し、１００μｍ銅配線におけるディッシングを測定した。
研磨終了後の１００μｍ銅配線におけるディッシングは、３５００Åであった。
【００４６】
上記のように、本発明の研磨方法による実施例１０及び１１では、研磨終了後の１００μｍ銅配線におけるディッシングは５００Å未満であり、充分に平坦化された精度の高い仕上げ面が得られた。一方、比較例７では、研磨終了後の１００μｍ銅配線におけるディッシングは３５００Åと大きく、平坦化が不十分な仕上げ面しか得られなかった。
【００４７】
【発明の効果】
本発明によれば、被加工膜を適度な速度で同程度に研磨することができ、スクラッチやディッシングを生ずることのない、半導体装置の製造において有用な化学機械研磨用水系分散体を得ることができる。[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a chemical mechanical polishing aqueous dispersion (hereinafter referred to as “chemical mechanical polishing aqueous dispersion”, which is also abbreviated as “aqueous dispersion”) used in the manufacture of semiconductor devices. More specifically, the present invention can efficiently polish various types of work films provided on a semiconductor substrate, and can obtain a sufficiently flat and highly accurate finished surface. The present invention relates to an aqueous dispersion for chemical mechanical polishing.
[0002]
[Prior art]
As a recent technology in the manufacture of semiconductor devices, after forming holes or grooves in an insulating film on a process wafer, a barrier metal layer made of hard metal or the like is formed, and then wiring such as tungsten, aluminum, and copper is formed. There is a method of forming wiring by embedding a material and then removing the wiring material and the barrier metal layer above the surface of the insulating film by chemical mechanical polishing. Wiring formed by this method is called damascene wiring.
The polishing for forming the damascene wiring has the following problems.
A relatively soft wiring material such as copper is easily polished, and when the width of the wiring portion is wide, the center portion of the wiring is excessively polished, so-called dishing is likely to occur, and a flat finished surface may not be obtained. In addition, the wiring may be disconnected due to generation of scratches.
In addition, a porous insulating film having a low dielectric constant or the like cannot obtain a sufficient polishing rate when the pH of the aqueous dispersion used for polishing is low, and is excessively polished when the pH is high. . In either case, it is not easy to suppress the generation of scratches.
On the other hand, it is not easy to efficiently polish a barrier metal layer made of a hard metal such as tantalum.
[0003]
Normally, chemical mechanical polishing of a wafer requires another stage of polishing process. Most generally, a two-stage polishing method is employed in which a wiring material such as copper is mainly polished in the first stage and the barrier metal layer is mainly polished in the second stage. Several methods have been proposed for this two-stage polishing, and many aqueous dispersions used for it have been proposed. As a first method, after polishing until copper is completely removed in the first stage polishing, there is a method in which only the barrier metal layer is removed by the second stage polishing. In this case, there is a problem that dishing that occurs at least in the first-stage polishing cannot be corrected by the second-stage polishing that mainly polishes the barrier metal layer, and it may be difficult to form a good damascene wiring.
As a second method, in the first stage polishing, copper is removed incompletely to such an extent that dishing does not occur in the wiring portion, and in the second stage polishing, the barrier metal layer is removed together with the remaining copper. A method has been proposed. According to this method, there may be a problem that the smoothness of the finished surface is insufficient, or that a long time is required for finishing the polishing and the cost is further increased.
[0004]
[Problems to be solved by the invention]
  The present invention solves the above-described conventional problems. That is, an object of the present invention is to provide a chemical mechanical polishing aqueous dispersion that is useful in the manufacture of a semiconductor device and that can provide a sufficiently flat finished surface with high accuracy and can form good damascene wiring. .
[0005]
[Means for Solving the Problems]
  In polishing a film to be processed provided on a semiconductor substrate, an investigation was made for the purpose of obtaining an aqueous dispersion for chemical mechanical polishing capable of sufficiently flattening the finished surface..
[0006]
The invention of claim 1 is a chemical mechanical polishing aqueous dispersion containing an abrasive, water, and a polishing rate adjusting component, wherein the abrasive is at least one of silica and inorganic-organic composite particles. And the polishing rate adjusting component is maleate ion, and the concentration of the maleate ion is 0.005 to 1 mol / liter, an aqueous dispersion for chemical mechanical polishing used for manufacturing a semiconductor device It is.
The invention of claim 2 is characterized in that the pH of the invention of claim 1 is 8-11.
The invention of claim 3 is characterized in that, in the invention of claim 1 or 2, the cation of the maleate ion pair is a potassium ion, and the polishing rate adjusting component is derived from potassium maleate. To do.
According to a fourth aspect of the invention, there is provided the method according to any one of the first to third aspects, wherein the inorganic-organic composite particles are formed by attaching silica particles to the surface of polymethyl methacrylate-based particles.
The invention according to claim 5 is the one according to any one of claims 1 to 4.When the copper film, the barrier metal layer, and the insulating film are polished under the same conditions, the polishing rate (R_Cu) And the barrier metal layer polishing rate (R_BM) Ratio (R)_Cu/ R_BM) Is 0.5 to 2, and the polishing rate of the copper film (R_Cu) And the polishing rate (R_In) Ratio (R)_Cu/ R_In) Is 0.5-2.
  The aqueous dispersion for chemical mechanical polishing of the present invention is useful as an aqueous dispersion used in the damascene wiring forming process, particularly for the second stage polishing.
  The copper forming the “copper film” includes not only pure copper but also an alloy containing 95% by weight or more of copper, such as copper-silicon and copper-aluminum. The metal forming the “barrier metal layer” includes tantalum, titanium, and the like, and may be nitrides or oxides thereof. For example, the nitride includes tantalum nitride and titanium nitride. The “tantalum, titanium, etc.” is not limited to pure tantalum and pure titanium, but includes tantalum such as tantalum-niobium, and alloys containing titanium. Further, the “tantalum nitride, titanium nitride” is not limited to a pure product.
  The barrier metal layer is preferably tantalum and / or tantalum nitride.
[0007]
As the insulating film, SiO₂In addition to the film, it also includes a low dielectric constant interlayer insulating film for the purpose of improving the performance of the VLSI. As a low dielectric constant insulating film, fluorine-added SiO₂(Dielectric constant: about 3.3 to 3.5), polyimide resin (dielectric constant: about 2.4 to 3.6, manufactured by Hitachi Chemical Co., Ltd., trade name “PIQ”, manufactured by Allied Signal, trade name "FLARE" etc.), benzocyclobutene (dielectric constant: about 2.7, manufactured by Dow Chemical, trade name "BCB" etc.), hydrogen-containing SOG (dielectric constant: about 2.5-3.5) and organic SOG (Dielectric constant: about 2.9, manufactured by Hitachi Chemical Co., Ltd., trade name “HSGR7”, etc.).
[0008]
The above “same condition” means that a specific type of polishing apparatus is used, and the rotation speed of the platen and head, polishing pressure, polishing time, type of polishing pad used, and supply amount of aqueous dispersion per unit time Means to be the same.
As long as these conditions are compared under the same conditions, appropriate conditions can be adopted, but it is desirable to adopt actual polishing conditions or conditions close thereto. For example, the platen rotation number is 30 to 120 rpm, preferably 40 to 100 rpm, the head rotation number is 30 to 120 rpm, preferably 40 to 100 rpm, and the ratio of the platen rotation number / head rotation number is 0.5 to 2. , Preferably 0.7 to 1.5, and the polishing pressure is 100 to 500 g / cm², Preferably 200 to 350 g / cm²The aqueous dispersion supply rate is 50 to 300 ml / min, preferably 100 to 200 ml / min.
The “ratio” of the polishing rate can be calculated from the values of the respective polishing rates obtained by polishing the copper film, the barrier metal layer, and the insulating film separately under the same conditions. This polishing can be performed using a wafer provided with a copper film, a barrier metal layer, or an insulating film.
[0009]
  In claim 5Copper film polishing rate (R_Cu) And barrier metal layer polishing rate (R_BM) Ratio (R)_Cu/ R_BM) Is 0.5 to 2, preferably 0.7 to 1.5, particularly preferably 0.8 to 1.2, and more preferably 0.9 to 1.1. This ratio (R_Cu/ R_BM) Is less than 0.5, the copper film is not polished at a sufficient speed, and the removal of the copper film other than the grooves or holes on the insulating film is incomplete in the first stage polishing in the two-stage polishing method. In this case, it takes a long time to remove the unnecessary copper film in the second stage polishing. On the other hand, the ratio (R_Cu/ R_BM) Exceeds 2, the copper film is excessively polished, causing dishing and causing a problem that good damascene wiring cannot be formed.
[0010]
  Also,In claim 5Copper film polishing rate (R_Cu) And polishing rate of insulating film (R_In) Ratio (R)_Cu/ R_In) Is 0.5 to 2, preferably 0.7 to 1.5, particularly 0.8 to 1.2, more preferably 0.9 to 1.1. This R_Cu/ R_InWhen the thickness exceeds 2, the copper film is excessively polished, and when this aqueous dispersion is used for polishing a film to be processed provided on a semiconductor substrate, dishing occurs in the wiring portion and the film is sufficiently flattened. It is not possible to obtain a highly accurate finished surface. On the other hand, R_Cu/ R_InIf it is less than 0.5, the insulating film is excessively polished, and good damascene wiring cannot be formed.
[0011]
  In the present invention, as an abrasive,silicaAnd at least one of inorganic-organic composite particles can be used.
[0013]
The inorganic-organic composite particles are not particularly limited as long as the inorganic particles and the organic particles are integrally formed to such an extent that they are not easily separated during polishing.
The composite particles are obtained by polycondensing alkoxysilane, aluminum alkoxide, titanium alkoxide, etc. in the presence of polymer particles such as polystyrene, polymethylmethacrylate, etc., and polysiloxane etc. are bonded to at least the surface of the polymer particles. Things can be used. The produced polycondensate may be directly bonded to the functional group of the polymer particles, or may be bonded via a silane coupling agent or the like.
In addition, this polycondensate does not necessarily need to be chemically bonded to the polymer particles. In particular, the polycondensate grown in three dimensions is physically held on the surface of the polymer particles. There may be. Further, silica particles, alumina particles, or the like can be used instead of alkoxysilane or the like. These may be held in entanglement with polysiloxane or the like, or may be chemically bonded to the polymer particles by a functional group such as a hydroxyl group which they have.
[0014]
As the composite particles, an aqueous dispersion containing inorganic particles having different zeta potentials and organic particles having different signs can be used in which these particles are combined by electrostatic force.
The zeta potential of polymer particles is often negative over the entire pH range or a wide range excluding the low pH range, but by making polymer particles having carboxyl groups, sulfonic acid groups, etc., more The polymer particles can surely have a negative zeta potential. Moreover, it can also be set as the polymer particle which has a positive zeta potential in a specific pH range by setting it as the polymer particle which has an amino group etc.
On the other hand, the zeta potential of inorganic particles is highly pH-dependent and has an isoelectric point at which this potential becomes 0, and the sign of the zeta potential is reversed before and after that.
Therefore, by combining specific inorganic particles and organic particles and mixing them in a pH range in which the zeta potential has an opposite sign, the inorganic particles and the organic particles can be combined together by electrostatic force. Further, even when the zeta potential has the same sign during mixing, the inorganic particles and the organic particles can be integrated by changing the pH and setting the zeta potential to the opposite sign.
[0015]
Furthermore, as the composite particles, in the presence of the particles integrally combined by electrostatic force as described above, alkoxysilane, aluminum alkoxide, titanium alkoxide and the like are polycondensed as described above, and at least on the surface of the particles, Further, a compound obtained by combining polysiloxane and the like can also be used.
[0016]
It is preferable that the average particle diameter of an abrasive grain is 0.01-3 micrometers. If this average particle diameter is less than 0.01 μm, an aqueous dispersion having a sufficiently high polishing rate may not be obtained. On the other hand, when the average particle diameter of the abrasive grains exceeds 3 μm, the abrasive grains settle and separate, and it is not easy to obtain a stable aqueous dispersion. The average particle size is 0.05 to 1.0 μm, and more preferably 0.1 to 0.7 μm. An abrasive having an average particle diameter in this range can provide a stable aqueous dispersion for CMP that has a sufficient polishing rate and does not cause sedimentation or separation of particles. The average particle diameter can be measured by observing with a transmission electron microscope.
[0017]
  The content of the abrasive grains can be 0.05 to 30 parts, preferably 0.1 to 30 parts, when the aqueous dispersion is 100 parts by weight (hereinafter abbreviated as “parts”). It is preferably 20 parts, particularly 0.5 to 10 parts, more preferably 1 to 7 parts. When the abrasive content is less than 0.05 part, the polishing rate is insufficient. On the other hand, if the content exceeds 30 parts, the cost increases and the stability of the aqueous dispersion decreases, which is not preferable.
  Function as these abrasive grainssilicaThe shape of the composite particles is preferably spherical. The spherical shape also means a substantially spherical shape that does not have an acute angle portion, and is not necessarily close to a true sphere. By using spherical abrasive grains, polishing can be performed at a sufficient speed, and generation of scratches and the like on the surface to be polished can be suppressed.
[0018]
  The aqueous dispersion of the present invention achieves the above specific polishing rate ratio by containing a polishing rate adjusting component.
  Such polishing rate adjusting componentIsMaleic acidIt is.
[0019]
  The aboveMaleic acidIs added to the aqueous dispersion, the dissociation part may or may not be dissociated. Also,Maleic acidThe dissociation part may be monovalent or more. Moreover, the cation of the pair of dissociation part may be any of hydrogen ions and other cations derived from additives that are optionally added, such as ammonium ions and potassium ions.
  In addition, the aboveMaleneAcidMaleic acidion(Maleic acidSalt)), in this caseMaleic acidThe ion may be monovalent or more in the dissociation part. Moreover, the cation of the pair of dissociation part may be any of hydrogen ions and other cations derived from additives that are optionally added, such as ammonium ions and potassium ions.
[0020]
  Maleic acid is dissociated substantially in its entirety in the aqueous dispersion to form maleate ions and a pair of cations. Here, the pair of cations may be any of hydrogen ions and other cations derived from additives that are optionally added, such as ammonium ions and potassium ions, but potassium ions are preferred.
  Maleate ion concentration is 0.005 to 1 mol / literAndIn particular, 0.01 to 0.5 mol / liter is preferable. In order to realize the concentration range of maleic acid ions, the amount of maleic acid added may be 0.06 to 11.6% by mass, particularly 0.1 to 5.8% by mass.
  When the maleate ion concentration is less than 0.005 mol / liter, the polishing rate of the copper film and the barrier metal may be insufficient. On the other hand, when the concentration of maleate ions exceeds 1 mol / liter, the surface to be polished may be corroded, and a good finished surface with high accuracy may not be obtained. The concentration of maleate ions can be measured by ion chromatography.
[0021]
Potassium ions generated as a pair of cations and the like also have an action of improving the polishing rate and can be an aqueous dispersion having a higher polishing rate. An appropriate concentration of potassium ions can be adopted, but it is preferably 0.01 to 2 mol / liter, more preferably 0.02 to 1 mol / liter. In this case, if the potassium ion concentration is less than 0.01 mol / liter, the effect of improving the polishing rate may not be sufficiently exhibited, whereas if it exceeds 2 mol / liter, scratches may be easily generated.
In order to produce the maleate ion and potassium ion, it is most convenient and effective to use potassium maleate. Potassium ions include those generated from potassium maleate, those generated from potassium hydroxide used to adjust the pH of aqueous dispersions, and those derived from optional additives. Also good.
[0022]
The aqueous dispersion of the present invention preferably contains an oxidizing agent. By containing the oxidizing agent, the polishing rate is improved.
A wide range of oxidizing agents can be used as the oxidizing agent, but suitable oxidizing agents include oxidizing metal salts, oxidizing metal complexes, non-metallic oxidizing agents such as peracetic acid, periodic acid, and iron ions. For example, ditolate, sulfate, EDTA, citrate, potassium ferricyanide, aluminum salts, sodium salts, potassium salts, ammonium salts, quaternary ammonium salts, phosphonium salts, or other cationic salts of peroxides, chlorates, chlorides Acid salts, nitrates, manganates, persulfates, and mixtures thereof.
[0023]
As the “oxidant”, hydrogen peroxide is particularly preferable. At least a part of hydrogen peroxide is dissociated to generate hydrogen peroxide ions. “Hydrogen peroxide” means one containing the hydrogen peroxide ions in addition to molecular hydrogen peroxide.
The concentration of hydrogen peroxide in the above can be arbitrarily set in the range of 0.01 to 5.0% by mass, more preferably 0.05 to 3.0% by mass, and 0.07 to 1.%. It is especially preferable to set it as 0 mass%. If the concentration of hydrogen peroxide is less than 0.01% by mass, polishing may not be possible at a sufficient rate, while if it exceeds 5.0% by mass, the surface to be polished may corrode.
[0024]
The aqueous dispersion of the present invention may contain a polyvalent metal ion that has an action of promoting the function of hydrogen peroxide as an oxidizing agent and can further improve the polishing rate.
Examples of the polyvalent metal ions include ions of metals such as aluminum, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, germanium, zirconium, molybdenum, tin, antimony, tantalum, tungsten, lead, and cerium. Is mentioned. These may be only one kind, or two or more kinds of polyvalent metal ions may coexist.
The content of the polyvalent metal ion can be 3000 ppm or less, particularly 10 to 2000 ppm with respect to the aqueous dispersion.
This polyvalent metal ion can be generated by blending a salt or complex such as nitrate, sulfate, acetate, etc. containing a polyvalent metal element in an aqueous medium, and by blending an oxide of a polyvalent metal element. It can also be made. Moreover, even if it is a compound mix | blended with an aqueous medium and a monovalent | monohydric metal ion produces | generates, what this ion turns into a polyvalent metal ion with an oxidizing agent can also be used. Of the various salts and complexes, iron nitrate is particularly preferable because it is particularly excellent in the action of improving the polishing rate.
[0025]
The pH of the aqueous dispersion of the present invention is preferably 8 to 11, and is preferably adjusted to 8.5 to 10.5, particularly 9 to 10. The pH can be adjusted with an acid such as nitric acid or sulfuric acid, or an alkali such as potassium hydroxide, sodium hydroxide or ammonia. When the pH of the aqueous dispersion is less than 8, the etching effect on the film to be processed such as copper is strong, and dishing, erosion, and the like may easily occur. On the other hand, if the pH exceeds 11, there may be a problem that the insulating film is excessively polished and a good wiring pattern cannot be obtained.
[0026]
The aqueous dispersion of the present invention is useful in the second stage polishing in the two stage polishing. In the first stage of polishing, R_Cu/ R_BMIs particularly useful in the second stage polishing when an aqueous dispersion of 20 or more, particularly 40 or more, and further 50 or more is used.
When the aqueous dispersion of the present invention is used in a one-step polishing method and / or when used in the first step of a two-step polishing method, it takes time for polishing, and a large amount of an aqueous dispersion is required. This may be economically disadvantageous.
When the aqueous dispersion of the present invention is used in the second stage of the two-stage polishing method, the R of the aqueous dispersion used in the first stage polishing is used._Cu/ R_BMIs less than 20, it takes a long time for the first stage polishing and a large amount of aqueous dispersion is required, which is not preferable.
[0027]
  Polishing of a film to be processed and a barrier metal layer of a semiconductor device is performed using a commercially available chemical mechanical polishing apparatus (for example, LGP510, LGP552 (hereinafter, manufactured by LAPMASTER SFT), EPO-113, EPO-222 (hereinafter, EBARA CORPORATION). ), Mirra (Applied Materials), AVANTI-472 (Ipec) and the like.
  In this polishing, it is preferable to remove the polishing agent remaining on the surface to be polished after polishing. The removal of the abrasive can be performed by a normal cleaning method..
[0028]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in more detail by way of examples.
[1] Preparation of aqueous dispersion containing abrasive grains
(1) Preparation of aqueous dispersion containing inorganic particles
(1) Preparation of aqueous dispersion containing fumed silica or fumed alumina
In a 2 liter polyethylene bottle, 100 g of fumed silica particles (Nippon Aerosil Co., Ltd., trade name “Aerosil # 90”), fumed alumina particles (Degussa Co., Ltd., trade name “Aluminium Oxide C”) After the addition, ion exchange water was added to make the total amount 1000 g. Next, the particles were dispersed by an ultrasonic disperser to prepare an aqueous dispersion containing 10 parts of fumed silica particles or fumed alumina particles.
[0029]
(2) Preparation of aqueous dispersion containing colloidal silica
A 2 liter flask is charged with 70 g of 25% by mass ammonia water, 40 g of ion exchange water, 175 g of ethanol and 21 g of tetraethoxysilane, heated to 60 ° C. with stirring at 180 rpm, and stirred at this temperature for 2 hours. After continuing, the mixture was cooled to obtain a colloidal silica / alcohol dispersion having an average particle size of 0.23 μm. Subsequently, an evaporator was used several times to remove the alcohol content while adding ion-exchanged water to the dispersion at a temperature of 80 ° C., and the alcohol in the dispersion was removed and water having a solid content concentration of 8% by mass. A dispersion was obtained.
[0030]
(2) Preparation of aqueous dispersion containing composite particles
(1) Aqueous dispersion containing polymer particles
90 parts of methyl methacrylate, 5 parts of methoxypolyethylene glycol methacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., trade name “NK Ester M-90G”, # 400), 5 parts of 4-vinylpyridine, azo polymerization initiator ( 2 parts of Wako Pure Chemical Industries, Ltd., trade name “V50”) and 400 parts of ion-exchanged water are put into a 2 liter flask and heated to 70 ° C. with stirring in a nitrogen gas atmosphere for 6 hours. Polymerized. As a result, an aqueous dispersion containing polymethylmethacrylate particles having an amino group cation and a functional group having a polyethylene glycol chain and an average particle diameter of 0.15 μm was obtained. The polymerization yield was 95%.
[0031]
(2) Water dispersion containing composite particles
100 parts of an aqueous dispersion containing 10% by weight of the polymethyl methacrylate particles obtained in (1) was put into a 2 liter flask, 1 part of methyltrimethoxysilane was added, and the mixture was stirred at 40 ° C. for 2 hours. . Thereafter, the pH was adjusted to 2 with nitric acid to obtain an aqueous dispersion (a). Further, the pH of an aqueous dispersion containing 10% by mass of colloidal silica (manufactured by Nissan Chemical Co., Ltd., trade name “Snowtex O”) was adjusted to 8 with potassium hydroxide to obtain an aqueous dispersion (b). The zeta potential of the polymethylmethacrylate particles contained in the water dispersion (a) was +17 mV, and the zeta potential of the silica particles contained in the water dispersion (b) was −40 mV.
[0032]
Thereafter, 50 parts of water dispersion (b) is gradually added to 100 parts of water dispersion (a) over 2 hours, mixed, stirred for 2 hours, and preliminary particles having silica particles attached to polymethyl methacrylate particles. An aqueous dispersion containing was obtained. Next, 2 parts of vinyltriethoxysilane is added to this aqueous dispersion and stirred for 1 hour, then 1 part of tetraethoxysilane is added, the temperature is raised to 60 ° C., and stirring is continued for 3 hours, followed by cooling. As a result, an aqueous dispersion containing composite particles was obtained. The average particle size of the composite particles was 180 nm, and silica particles were attached to 80% of the surface of the polymethyl methacrylate particles.
[0033]
[2] Preparation of chemical mechanical polishing aqueous dispersion
Example 1
[1] The aqueous dispersion containing fumed silica prepared in (1), (1) was added so that the fumed silica was 5 parts, and potassium maleate and hydrogen peroxide were each 1% by mass. The aqueous dispersion for CMP was obtained by blending in ion exchange water to a concentration of 0.1% by mass and adjusting the pH to 9.5 with potassium hydroxide.
[0034]
Examples 2-9
An aqueous dispersion for CMP having a specific pH was obtained in the same manner as in Example 1 except that the type and amount of abrasive grains and the amount of potassium maleate and hydrogen peroxide were as shown in Table 1.
[0035]
Comparative Example 1
An aqueous dispersion for CMP having a specific pH was obtained in the same manner as in Example 1 except that the polishing rate adjusting component was not added.
Comparative Examples 2-6
An aqueous dispersion for CMP having a specific pH was obtained in the same manner as in Example 1 except that the abrasive grains, the type and mixing amount of the polishing rate adjusting component, and the mixing amount of hydrogen peroxide were changed as shown in Table 2. It was. However, in Comparative Example 5, the pH was adjusted to a specific pH using nitric acid instead of potassium hydroxide.
[0036]
As described above, using the chemical mechanical polishing aqueous dispersions of Examples 1 to 9 and Comparative Examples 1 to 6, a wafer with an 8-inch copper film, a wafer with an 8-inch tantalum film, a wafer with an 8-inch tantalum nitride film, and an 8-inch plasma The wafer with TEOS film was polished. The results are shown in Tables 1 and 2.
[0037]
A model “LGP-510” manufactured by Lapmaster Co., Ltd. was used as a polishing apparatus, the film provided on each wafer was polished under the following conditions, and the polishing rate was calculated according to the following formula.
Table rotation speed: 50 rpm, head rotation speed: 50 rpm, polishing pressure: 300 g / cm², Aqueous dispersion supply rate: 100 ml / min, polishing time: 1 minute, polishing pad; two-layer structure of Rodel Nitta Co., product number IC1000 / SUBA400
Polishing rate (Å / min) = (thickness of each film before polishing−thickness of each film after polishing) / polishing time
[0038]
The thickness of each film is determined by measuring the sheet resistance by a direct current four-probe method using a resistivity measuring device (manufactured by NPS, model “Σ-5”), and the sheet resistance value and copper, tantalum, tantalum nitride or It calculated by the following formula from the resistivity of plasma TEOS.
Thickness (Å) of each film = [sheet resistance value (Ω / cm²) × Resistivity of copper, tantalum, tantalum nitride or plasma TEOS (Ω / cm)] × 10⁸
Moreover, the evaluation of the scratch of the copper film was performed by irradiating a spotlight in a dark room and visually confirming the presence or absence of the scratch.
For evaluation of scratches on the insulating film, photographs were taken with a differential interference microscope, and scratches in a field of view of 100 μm × 100 μm were counted.
[0039]
[Table 1]

[0040]
[Table 2]

[0041]
According to the results of Table 1, in the aqueous dispersions of Examples 1 to 9 in which 1 to 3 parts of potassium maleate and 0.1 to 3 parts of hydrogen peroxide were mixed, a copper film and a tantalum film and / or nitriding Ratio of polishing rate with tantalum film (R_Cu/ R_BM), And ratio of polishing rate between copper film and insulator (R_Cu/ R_In) Was in the range of 0.5-2. In particular, Examples 4 to 6 using composite particles or a mixture of composite particles and fumed silica as the abrasive were R_Cu/ R_BMAnd R_Cu/ R_inIn the range of 0.8 to 1.2, the scratches of the copper film and the insulating film are very small, and it is shown that a sufficiently flat finished surface with high accuracy can be obtained.
[0042]
On the other hand, according to the results of Table 2, in Comparative Examples 1 to 5, the ratio of the polishing rate between the copper film and the tantalum film and / or the tantalum nitride film (R_Cu/ R_BM), And ratio of polishing rate between copper film and insulator (R_Cu/ R_In) Was very large or very small, indicating a finished surface with poor planarization.
R_Cu/ R_BMIn Comparative Example 6 using the first-stage aqueous dispersion with = 100, the polishing rate R of the copper film was R_CuIs the ratio of the polishing rate between the copper film and the tantalum film and / or tantalum nitride film (R_Cu/ R_BM), And ratio of polishing rate between copper film and insulator (R_Cu/ R_In) Is small, indicating that only a finished surface with insufficient planarization can be obtained.
[0043]
Example 10
On the surface of the substrate made of silicon, an insulating film having a pattern formed by grooves having a depth of 5, 10, 25, 50, 75, and 100 μm at a depth of 1 μm was laminated. Next, a 300-nm TaN film was formed on the surface of the insulating film, and then copper was deposited by sputtering and plating in a groove covered with the TaN film to produce a wafer.
A model “LGP-510” manufactured by LAPMASTER SFT Co., Ltd. was used as a polishing apparatus, and the wafer prepared above was polished in two stages under the following conditions. However, in the first stage polishing, the fumed silica aqueous dispersion (R_Cu/ R_BM= 30) for 3 minutes, and then polishing as a second stage polishing using the same aqueous dispersion as used in Example 5 until the remaining copper and TaN are completely removed did.
Table rotation speed: 50 rpm, head rotation speed: 50 rpm, polishing pressure: 300 g / cm², Aqueous dispersion supply rate: 100 ml / min, polishing pad; two-layer structure of Rodel Nitta, part number IC1000 / SUBA400
After polishing, the dishing in a copper wiring with a width of 100 μm was measured using a surface roughness meter (model “P-10” manufactured by KLA-Tencor), and it was 450 mm.
[0044]
Example 11
As the aqueous dispersion for polishing at the second stage, the same aqueous dispersion as that used in Example 6 was used, but the two-stage polishing was performed in the same manner as in Example 10, and dishing in a 100 μm copper wiring was measured. .
The dishing in the 100 μm copper wiring after the polishing was 470 mm.
[0045]
Comparative Example 7
As the aqueous dispersion for polishing at the second stage, the same aqueous dispersion as that used in Comparative Example 3 was used, except that two-stage polishing was performed in the same manner as in Example 10, and dishing in a 100 μm copper wiring was measured. .
The dishing in the 100 μm copper wiring after polishing was 3500 mm.
[0046]
As described above, in Examples 10 and 11 according to the polishing method of the present invention, the dishing in the 100 μm copper wiring after the polishing was less than 500 mm, and a sufficiently smooth and highly accurate finished surface was obtained. On the other hand, in Comparative Example 7, the dishing in the 100 μm copper wiring after polishing was as large as 3500 mm, and only a finished surface with insufficient planarization was obtained.
[0047]
【The invention's effect】
  According to the present invention, it is possible to obtain a chemical mechanical polishing aqueous dispersion that can polish a film to be processed to the same extent at an appropriate speed and that is useful in the manufacture of semiconductor devices without causing scratches or dishing. it can.

Claims (5)

  A chemical mechanical polishing aqueous dispersion comprising an abrasive, water, and a polishing rate adjusting component,
  The abrasive is at least one of silica and inorganic-organic composite particles;
  An aqueous dispersion for chemical mechanical polishing used in the production of a semiconductor device, wherein the polishing rate adjusting component is maleate ions, and the concentration of the maleate ions is 0.005 to 1 mol / liter.   The chemical mechanical polishing aqueous dispersion according to claim 1, wherein the pH is 8 to 11.   3. The chemical mechanical polishing aqueous dispersion according to claim 1, wherein the cation of the maleate ion pair is potassium ion, and the polishing rate adjusting component is derived from potassium maleate.   4. The chemical mechanical polishing aqueous dispersion according to claim 1, wherein the inorganic-organic composite particles are formed by attaching silica particles to the surface of polymethyl methacrylate particles. 5.   When the copper film, barrier metal film, and insulating film are polished under the same conditions, the polishing rate of the copper film ( R _Cu ) And the barrier metal film polishing rate ( R _BM ) Ratio ( R _Cu / R _BM ) Is 0.5 to 2, and the polishing rate of the copper film ( R _Cu ) And the polishing rate of the insulating film ( R _In ) Ratio ( R _Cu / R _In The chemical mechanical polishing aqueous dispersion according to any one of claims 1 to 4, wherein: