KR101048744B1 - Cobalt Alloy-based Multilayer Diffusion Film Formation by Electroless Plating - Google Patents
Cobalt Alloy-based Multilayer Diffusion Film Formation by Electroless Plating Download PDFInfo
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- KR101048744B1 KR101048744B1 KR1020080092350A KR20080092350A KR101048744B1 KR 101048744 B1 KR101048744 B1 KR 101048744B1 KR 1020080092350 A KR1020080092350 A KR 1020080092350A KR 20080092350 A KR20080092350 A KR 20080092350A KR 101048744 B1 KR101048744 B1 KR 101048744B1
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
- C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
- C23C18/31—Coating with metals
- C23C18/32—Coating with nickel, cobalt or mixtures thereof with phosphorus or boron
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C19/00—Alloys based on nickel or cobalt
- C22C19/07—Alloys based on nickel or cobalt based on cobalt
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
- C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
- C23C18/1601—Process or apparatus
- C23C18/1633—Process of electroless plating
- C23C18/1675—Process conditions
- C23C18/1683—Control of electrolyte composition, e.g. measurement, adjustment
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
- C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
- C23C18/31—Coating with metals
- C23C18/32—Coating with nickel, cobalt or mixtures thereof with phosphorus or boron
- C23C18/34—Coating with nickel, cobalt or mixtures thereof with phosphorus or boron using reducing agents
- C23C18/36—Coating with nickel, cobalt or mixtures thereof with phosphorus or boron using reducing agents using hypophosphites
Abstract
본 발명에 따른 다층 확산방지막 형성방법은, 구리배선의 표면에 2단계의 무전해 도금을 통해 서로 다른 조성을 가지는 2층의 코발트 합금계열의 확산방지막을 순차적으로 형성하는 것을 특징으로 한다. 이러한 예로서, 상기 확산방지막의 하부층은 Co-W-P 합금으로 이루어지고, 상기 확산방지막의 상부층은 Co-B 합금으로 이루어지는 것이 바람직하다. 본 발명에 의하면, 금속 배선 물질인 구리 또는 그의 합금의 신뢰성을 높이기 위해 화학적-기계적 연마 이후 공기 중에 노출되는 구리 배선의 상부 표면에 형성하는 무전해 도금 확산방지막의 성능을 개선시킬 수 있다. 구체적으로 구리 배선의 산화에 대한 저항성이 개선되고, 구리 배선과 확산방지막의 계면 사이의 특성을 개선하여 일렉트로마이그레이션(electromigration) 에 의한 배선의 손상을 최소화시킬 수 있다. The method for forming a multilayer diffusion barrier according to the present invention is characterized by sequentially forming a diffusion barrier of two layers of cobalt alloy series having different compositions through two steps of electroless plating on the surface of a copper wiring. In this example, the lower layer of the diffusion barrier is made of Co-W-P alloy, the upper layer of the diffusion barrier is preferably made of Co-B alloy. According to the present invention, it is possible to improve the performance of the electroless plating diffusion barrier film formed on the upper surface of the copper wiring exposed to air after chemical-mechanical polishing in order to increase the reliability of the copper or alloy thereof as the metal wiring material. Specifically, the resistance to oxidation of the copper wiring can be improved, and the damage between the wiring due to the electromigration can be minimized by improving the characteristics between the copper wiring and the interface of the diffusion barrier.
구리배선, 일렉트로마이그레이션, 산화, 무전해 도금, 코발트 Copper Wiring, Electromigration, Oxidation, Electroless Plating, Cobalt
Description
본 발명은 확산방지막 형성방법에 관한 것으로서, 특히 무전해 도금을 통한 코발트 합금 계열의 다층 확산방지막 형성방법에 관한 것이다.The present invention relates to a method of forming a diffusion barrier, and more particularly, to a method of forming a multilayer diffusion barrier of a cobalt alloy series through electroless plating.
최근 반도체 공정에서 점차 배선의 선폭이 감소함에 따라 배선의 단면적 및 배선 사이의 간격이 감소되고 있다. 배선의 단면적이 감소되면 배선 저항이 증가하게 되고, 배선 사이의 간격이 감소되면 신호의 지연이 발생하여 바람직하지 않다. 따라서 이러한 신호 지연을 줄이기 위해서 배선의 경우는 낮은 비저항 특성을 가지는 구리로, 절연층의 경우는 더 낮은 유전 상수를 가지는 물질로 대체되고 있다.Recently, as the line width of wiring decreases gradually in the semiconductor process, the cross-sectional area of the wiring and the space between the wirings are reduced. If the cross-sectional area of the wiring is reduced, the wiring resistance is increased, and if the distance between the wirings is reduced, signal delay occurs, which is undesirable. Therefore, in order to reduce such signal delay, the wiring is replaced by copper having a low resistivity characteristic and the insulating layer is replaced by a material having a lower dielectric constant.
구리 배선은 다마신 공정을 통해 형성되는데, 이 경우 구리 자체의 확산과 이로 인한 실리콘 기판 위의 소자의 성능 저하를 방지하기 위해, 구리배선을 확산방지막으로 둘러싸는 것이 매우 중요하다. 구리배선의 측면과 하부에 대해서는 구 리 배선 형성 이전에 확산방지막을 먼저 증착하였고, 화학 기계적 연마(CMP) 후에 드러나는 구리배선 표면에 대해서는 전 표면에 치밀한 조성의 절연막, 예컨대 SiCN, SiN 등을 증착하여 확산방지막으로 사용하여 왔다. Copper wiring is formed through a damascene process. In this case, it is very important to surround the copper wiring with a diffusion barrier layer in order to prevent diffusion of copper itself and deterioration of the device on the silicon substrate. On the side and the bottom of the copper wiring, the diffusion barrier film was first deposited before the copper wiring was formed. On the surface of the copper wiring exposed after the chemical mechanical polishing (CMP), an insulating film having a dense composition such as SiCN and SiN was deposited on the entire surface. It has been used as a diffusion barrier.
그러나 최근 들어 집적도가 계속 증가하면서, 이러한 고유전율 절연막이 배선 구조 전체의 유전율을 상당히 높이게 되면서 신호 지연을 증가시키는 효과가 나타나게 되었다. 따라서 최근 들어 절연체 유전막 대신 확산 방지 성능을 가지는 코발트 합금 계열의 무전해 도금 박막을 선택적으로 구리 배선 위에 형성시켜 확산방지막으로 이용하려는 연구가 활발히 진행되고 있다. However, in recent years, as the degree of integration continues to increase, the dielectric constant of such a high dielectric constant insulating layer significantly increases the signal structure. Therefore, in recent years, studies have been actively conducted to form a cobalt alloy-based electroless plating thin film having a diffusion barrier instead of an insulator dielectric layer and selectively use it as a diffusion barrier.
무전해 도금 확산방지막을 통해 얻을 수 있는 부가적인 효과로서 많이 언급되어 온 것은, 일렉트로마이그레이션(electromigration)에 의한 배선의 손상 방지에 무전해 도금 확산방지막이 매우 우수한 성능을 보인다는 것이다. 이러한 현상은 금속성의 무전해 도금 확산방지막이 고유전율 절연막에 비해 상대적으로 구리 배선과 매우 강한 접착력을 가지며, 이로 인해 계면에서의 구리 원자의 이동이 많이 억제되면서 일렉트로마이그레이션에 대한 저항성을 향상시킨다는 가설에 의해 설명되어지고 있다. 실제로, 많은 연구에서 일렉트로마이그레이션에 대한 저항성 개선에 따른 배선의 수명 증가가, 적게는 수 배에서 많게는 수십 배 이상으로 나타난다고 보고되고 있다. 이러한 성능 개선에 있어서는, CoWP 계열의 확산방지막이 우수한 것으로 평가되고 있다.It has been mentioned a lot as an additional effect that can be obtained through the electroless plating diffusion barrier film, and the electroless plating diffusion barrier film has a very excellent performance in preventing the damage of the wiring by electromigration. This phenomenon is based on the hypothesis that metallic electroless plating diffusion barrier has a very strong adhesive strength with copper wiring compared to the high dielectric constant insulating film, thereby suppressing the movement of copper atoms at the interface and improving the resistance to electromigration. It is explained by Indeed, many studies have reported that the lifespan of wiring due to the improved resistance to electromigration can be as small as several times as many as tens of times. In this performance improvement, it is evaluated that CoWP series diffusion barrier film is excellent.
무전해 도금 확산방지막에 의한 또 하나의 부가적인 성능 개선으로서, 산화 방지에 대한 영향이 있다. 구리는 공기중에 노출될 경우 알루미늄에서 나타나는 자 체 산화 방지막의 형성이 없다. 따라서 구리가 장시간 고온에서 노출되면 연속적으로 산화반응을 일으키게 되며, 이로 인해 형성된 산화막은 구리 박막의 비저항을 증가시킬 뿐만 아니라, 상부에 형성되는 확산방지막과의 접착력을 감소시킴으로서 일렉트로마이그레이션에 대한 저항성을 떨어트리는 원인이 되기도 한다. 많은 연구에서, CoB 계열의 무전해 도금 확산방지막이 산화에 대해 우수한 저항성을 가지는 것으로 나타났다. As an additional performance improvement by the electroless plating diffusion barrier, there is an effect on the prevention of oxidation. Copper does not form its own antioxidant film that appears in aluminum when exposed to air. Therefore, when copper is exposed to high temperature for a long time, the oxidation reaction is continuously performed, and the oxide film formed thereby not only increases the resistivity of the copper thin film but also decreases the adhesion to the diffusion barrier film formed thereon, thereby reducing the resistance to electromigration. Trees can also be the cause. Many studies have shown that the CoB series electroless plating diffusion barrier has excellent resistance to oxidation.
그러나 아직까지 이러한 확산방지막들 중 두 가지 성능이 모두 우수한 경우에 대해서는 알려지지 않고 있다. 즉 CoWP의 경우 우수한 확산방지 성능과 일렉트로마이그레이션에 대한 저항성을 가지고 있지만 산화에 대한 저항성은 상대적으로 떨어진다고 알려져 있으며, CoB의 경우 CoWP에 비해 확산방지 성능과 일렉트로마이그레이션에 대한 저항성이 떨어진다고 알려져 있다. However, it is not known yet that both of these diffusion barriers have excellent performance. In other words, CoWP is known to have excellent diffusion prevention performance and resistance to electromigration, but is relatively inferior to oxidation, and CoB is known to have low diffusion prevention performance and electromigration resistance compared to CoWP.
따라서 본 발명이 해결하고자 하는 과제는, 서로 다른 조성을 가지는 두 종류의 코발트 합금 박막을 무전해 도금으로 2층으로 구리배선 상에 형성하여 구리배선의 산화 저항성과 일렉트로마이그레이션에 대한 저항성을 동시에 개선시키는 코발트 합금계열의 다층 확산방지막 형성방법을 제공하는 데 있다. Accordingly, the problem to be solved by the present invention is to form two layers of cobalt alloy thin films having different compositions on the copper wiring by electroless plating, thereby simultaneously improving the oxidation resistance of the copper wiring and the resistance to the electromigration. The present invention provides a method of forming an alloy-based multilayer diffusion barrier film.
상기 과제를 달성하기 위한 본 발명에 따른 다층 확산방지막 형성방법은, 구리배선의 표면에 2단계의 무전해 도금을 통해 서로 다른 조성을 가지는 2층의 코발트 합금계열의 확산방지막을 순차적으로 형성하는 것을 특징으로 한다. The multi-layer diffusion barrier film forming method according to the present invention for achieving the above object is characterized by sequentially forming a diffusion barrier of two layers of cobalt alloy series having a different composition through the two-step electroless plating on the surface of the copper wiring. It is done.
이 때, 상기 확산방지막의 하부층은 상기 상부층에 비해 상기 구리배선의 일렉트로마이그레이션에 대해 더 우수한 저항성을 가지는 코발트 합금계열의 확산방지막으로 이루어지고, 상기 확산방지막의 상부층은 상기 하부층에 비하여 구리배선의 산화에 대해 더 우수한 저항성을 가지는 코발트 합금계열의 확산방지막으로 이루어지는 것이 바람직하다. 이러한 예로서, 상기 확산방지막의 하부층은 Co-W-P 합금으로 이루어지고, 상기 확산방지막의 상부층은 Co-B 합금으로 이루어지는 것이 바람직하다. At this time, the lower layer of the diffusion barrier film is made of a diffusion barrier film of cobalt alloy series having a better resistance to the electromigration of the copper wiring than the upper layer, the upper layer of the diffusion barrier film of the copper wiring compared to the lower layer. It is preferable that it is made of a diffusion barrier film of cobalt alloy series having better resistance to. In this example, the lower layer of the diffusion barrier is made of Co-W-P alloy, the upper layer of the diffusion barrier is preferably made of Co-B alloy.
상기 무전해 도금에 사용되는 무전해 도금 용액은 탈이온수를 주용매제로 하여, Co 이온(II) 함유 화합물, 환원제, pH 조절제, 착물 형성제, 및 기타 첨가제를 포함한다. 상기 확산방지막의 하부층을 형성하는 경우에는 상기 첨가제가 텅스텐 성분을 함유하고, 상기 확산방지막의 상부층을 형성하는 경우에는 상기 첨가제가 텅스텐 성분을 함유하지 않는 것이 바람직하다. 상기 확산방지막의 하부층을 형성하는 경우에 사용되는 상기 첨가제의 예로는 Na2WO4 를 들 수 있다. The electroless plating solution used for the electroless plating includes a Co ion (II) -containing compound, a reducing agent, a pH adjusting agent, a complex forming agent, and other additives using deionized water as the main solvent. When the lower layer of the diffusion barrier is formed, the additive contains a tungsten component, and when the upper layer of the diffusion barrier is formed, the additive does not contain a tungsten component. An example of the additive used in forming the lower layer of the diffusion barrier is Na 2 WO 4 .
상기 확산방지막의 하부층을 형성하는 경우에는 상기 하부층에 인이 포함되도록 상기 환원제로서 sodium hypophosphite, potassium hypophosphite, 및 ammonium hypophosphite 중에서 선택된 적어도 어느 하나를 포함한 것을 사용하 고, 상기 확산방지막의 상부층을 형성하는 경우에는 상기 상부층에 붕소가 포함되도록 상기 환원제로서 dimethylamine borane 및 sodium borohydride 중에서 선택된 적어도 어느 하나를 포함한 것을 사용하는 것이 바람직하다. In the case of forming the lower layer of the diffusion barrier layer, at least one selected from sodium hypophosphite, potassium hypophosphite, and ammonium hypophosphite is used as the reducing agent so that phosphorus is included in the lower layer, and the upper layer of the diffusion barrier layer is formed. It is preferable to use at least any one selected from dimethylamine borane and sodium borohydride as the reducing agent so that boron is included in the upper layer.
상기 무전해 도금에 사용되는 무전해 도금 용액의 pH는 8~11인 것이 바람직하며, 상기 무전해 도금은 40℃ 내지 90℃의 온도범위에서 이루어지는 것이 바람직하다. The pH of the electroless plating solution used for the electroless plating is preferably 8 to 11, the electroless plating is preferably made in a temperature range of 40 ℃ to 90 ℃.
본 발명에 의하면, 금속 배선 물질인 구리 또는 그의 합금의 신뢰성을 높이기 위해 화학적-기계적 연마 (CMP, Chemical mechanical polishing) 이후 공기 중에 노출되는 구리 배선의 상부 표면에 형성하는 무전해 도금 확산방지막의 성능을 개선시킬 수 있다. 구체적으로 구리 배선의 산화에 대한 저항성이 개선되고, 구리 배선과 확산방지막의 계면 사이의 특성을 개선하여 일렉트로마이그레이션(electromigration) 에 의한 배선의 손상을 최소화시킬 수 있다. According to the present invention, the electroless plating diffusion barrier layer formed on the upper surface of the copper wiring exposed to the air after chemical mechanical polishing (CMP) to improve the reliability of the metal wiring material copper or its alloys is improved. Can be improved. Specifically, the resistance to oxidation of the copper wiring can be improved, and the damage between the wiring due to the electromigration can be minimized by improving the characteristics between the copper wiring and the interface of the diffusion barrier.
이하에서, 본 발명의 바람직한 실시예를 첨부한 도면들을 참조하여 상세히 설명한다. 아래의 실시예는 본 발명의 내용을 이해하기 위해 제시된 것일 뿐이며 당 분야에서 통상의 지식을 가진 자라면 본 발명의 기술적 사상 내에서 많은 변형이 가능할 것이다. 따라서 본 발명의 권리범위가 이러한 실시예에 한정되는 것으로 해석돼서는 안 된다. Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following examples are only presented to understand the content of the present invention, and those skilled in the art will be capable of many modifications within the technical spirit of the present invention. Therefore, the scope of the present invention should not be construed as limited to these embodiments.
본 발명은 구리 배선의 표면에 서로 다른 조성을 가지는 코발트 합금계열의 확산방지막을 하부층과 상부층으로 구분되도록 무전해 도금 방법으로 순차적으로 2층 적층하되, 구리배선의 표면에 닿는 하부층으로는 상부층에 비해 구리배선의 일렉트로마이그레이션에 대해 더 우수한 저항성을 가지는 것을 증착하고, 그 위의 상부층으로는 하부층에 비하여 구리배선의 산화에 대해 더 우수한 저항성을 가지는 것을 증착하는 것을 특징으로 한다. According to the present invention, two layers of cobalt-based diffusion barriers having different compositions on the surface of the copper wiring are sequentially laminated by an electroless plating method so as to be divided into a lower layer and an upper layer. It is characterized by depositing a better resistance to the electromigration of the wiring, and having a higher resistance to the oxidation of the copper wiring than the lower layer as the upper layer thereon.
이 때 사용되는 무전해 도금 용액은 탈이온수(de-ionized water)를 주용매제로 사용하며, Co 이온(II) 함유 화합물, 환원제, pH 조절제, 착물 형성제, 및 기타 첨가제를 포함한다. 그리고 상기 첨가제로는 무전해 도금시 환원제의 분해로부터 발생하는 수소기포의 발생을 억제하기 위한 적절한 계면활성제나 소포제와, 용액의 안정을 유지하기 위한 안정제 등을 들 수 있다. The electroless plating solution used at this time uses de-ionized water as the main solvent, and includes a Co ion (II) -containing compound, a reducing agent, a pH adjusting agent, a complex forming agent, and other additives. Examples of the additive include suitable surfactants and antifoams for suppressing the generation of hydrogen bubbles resulting from decomposition of the reducing agent during electroless plating, and stabilizers for maintaining the stability of the solution.
상기 Co 이온(II) 함유 화합물로는 Cobalt(II) acetate, Cobalt(II) acetate tetrahydrate, Cobalt(II) acetylacetonate, Cobalt(II) acetylacetonate hydrate, Cobalt(II) benzoylacetonate, Cobalt(II) bromide, Cobalt(II) bromide hydrate, Cobalt(II) carbonate hydrate, Cobalt(II) chloride, Cobalt(II) chloride hexahydrate, Cobalt(II) cyanide dihydrate, Cobalt(II) 2-ethylhexanoate, Cobalt(II) fluoride, Cobalt(II) fluoride tetrahydrate, Cobalt(II) hexafluoroacetylacetonate, Cobalt(II) hydroxide, Cobalt(II) iodide, Cobalt(II) 2,3-naphthalocyanine, Cobalt(II) nitrate hexahydrate, Cobalt(II) oxalate dihydrate, Cobalt(II) oxide, Cobalt(II) perchlorate hexahydrate, Cobalt(II) phosphate hydrate, Cobalt(II) phthalocyanine, Cobalt(II) selenide, Cobalt(II) sulfate heptahydrate, Cobalt(II) sulfate hydrate, Cobalt(II) tetrafluoroborate, 및 Cobalt(II) thiocyanate 중에서 1 종 또는 2 종 이상이 혼합된 것을 사용할 수 있다. Co 이온(II) 함유 화합물의 첨가량은 0.001 wt% 내지 20 wt%가 바람직하며, 0.005 wt% 내지 10 wt%를 첨가하였을 때 효과적으로 코발트 합금 계열의 확산방지막(캡핑막)이 형성된다. Cobalt (II) -containing compounds include Cobalt (II) acetate, Cobalt (II) acetate tetrahydrate, Cobalt (II) acetylacetonate, Cobalt (II) acetylacetonate hydrate, Cobalt (II) benzoylacetonate, Cobalt (II) bromide, Cobalt ( II) bromide hydrate, Cobalt (II) carbonate hydrate, Cobalt (II) chloride, Cobalt (II) chloride hexahydrate, Cobalt (II) cyanide dihydrate, Cobalt (II) 2-ethylhexanoate, Cobalt (II) fluoride, Cobalt (II) fluoride tetrahydrate, Cobalt (II) hexafluoroacetylacetonate, Cobalt (II) hydroxide, Cobalt (II) iodide, Cobalt (II) 2,3-naphthalocyanine, Cobalt (II) nitrate hexahydrate, Cobalt (II) oxalate dihydrate, Cobalt (II) oxide , Cobalt (II) perchlorate hexahydrate, Cobalt (II) phosphate hydrate, Cobalt (II) phthalocyanine, Cobalt (II) selenide, Cobalt (II) sulfate heptahydrate, Cobalt (II) sulfate hydrate, Cobalt (II) tetrafluoroborate, and Cobalt ( II) Thiocyanate can use 1 type (s) or 2 or more types in mixture. The amount of the Co ion (II) -containing compound is preferably 0.001 wt% to 20 wt%, and when 0.005 wt% to 10 wt% is added, a cobalt alloy series diffusion barrier film (capping film) is effectively formed.
상기 환원제로는 상부 확산방지막과 하부 확산방지막의 형성에 사용되는 것이 다르다. The reducing agent is different from that used for forming the upper diffusion barrier and the lower diffusion barrier.
하부 확산방지막의 경우에는 구리 기판 위에서 직접 무전해 도금을 가능하게 하는 환원제를 1종 또는 2종 이상 포함하여야 하는데 그 예로 sodium hypophosphite, potassium hypophosphite, 및 ammonium hypophosphite 등을 들 수 있으며, 이러한 확산방지막 형성용 환원제를 통해서 무전해 도금 과정에서 하부 확산방지막에 인이 포함된다. 그리고, 하부 확산방지막에 텅스텐이 포함되도록 하부 확산방지막 형성용 무전해 도금용액은 텅스텐 성분을 함유하는 첨가제, 예컨대 sodium tungstate를 포함한다. 이 경우 하부 확산방지막으로서 Co-W-P 합금 박막이 형성된다. In the case of the lower diffusion barrier layer, one or two or more reducing agents that enable electroless plating directly on the copper substrate may be included. Examples thereof include sodium hypophosphite, potassium hypophosphite, and ammonium hypophosphite. Phosphorus is included in the lower diffusion barrier during the electroless plating process through the reducing agent. In addition, the electroless plating solution for forming the lower diffusion barrier layer includes an additive containing a tungsten component such as sodium tungstate so that tungsten is included in the lower diffusion barrier layer. In this case, a Co-W-P alloy thin film is formed as a lower diffusion barrier.
상부 확산방지막의 경우에는 환원제로서 dimethylamine borane, sodium borohydride 등을 사용할 수 있으며, 이러한 상부 확산방지막 환원제를 통해서 무전해 도금 과정에서 상부 확산방지막에 붕소가 포함된다. 상부 확산 방지막 형성용 무전해 도금용액에는 텅스텐 성분을 함유하는 첨가제가 포함되지 않는다. 이 경우 상부 확산방지막으로서 Co-B 합금 박막이 형성된다. 환원제의 첨가량은 0.001 wt% 내지 30 wt%가 바람직하며, 확산방지막의 보다 빠른 형성을 위해 0.005 wt% 내지 10 wt%를 첨가하는 것이 바람직하다. In the case of the upper diffusion barrier, dimethylamine borane, sodium borohydride, etc. may be used as the reducing agent, and boron is included in the upper diffusion barrier during the electroless plating process through the upper diffusion barrier reducing agent. The electroless plating solution for forming the upper diffusion barrier film does not contain an additive containing a tungsten component. In this case, a Co-B alloy thin film is formed as an upper diffusion barrier. The addition amount of the reducing agent is preferably 0.001 wt% to 30 wt%, and it is preferable to add 0.005 wt% to 10 wt% for faster formation of the diffusion barrier.
상기 pH 조절제로는 boric acid와 NaOH를 혼합하여 사용하는 것이 바람직하다. 도금액의 pH는 8~11인 것이 바람직하며, NaOH 대신에 KOH, tetramethylammonium hydroxide 등을 사용할 수도 있다. boric acid는 pH 조절의 완충제 역할을 한다. pH 조절제의 첨가량은 0.01 wt% 내지 20 wt%가 바람직하며, 용액의 안정을 위해 0.05 wt% 내지 10 wt%를 첨가하는 것이 바람직하다.As the pH adjusting agent, it is preferable to use a mixture of boric acid and NaOH. The pH of the plating solution is preferably 8-11, and KOH, tetramethylammonium hydroxide, or the like may be used instead of NaOH. Boric acid acts as a buffer for pH regulation. The addition amount of the pH adjusting agent is preferably 0.01 wt% to 20 wt%, and it is preferable to add 0.05 wt% to 10 wt% for the stability of the solution.
상기 착물 형성제로는 2염기 또는 3염기의 구연산염을 포함하는 화합물을 사용하는 것을 특징으로 한다. 그 예로는 ammonium citrate, di-ammonium hydrogen citrate, calcium citrate tribasic tetrahydrate, lithium citrate hydrate, sodium dihydrogen citrate, potassium citrate-1-hydrate, tri-sodium citrate hydrate, sodium citrate, sodium citrate tribasic dihydrate, tributyl citrate, triethyl citrate, trimethyl citrate, citrate phosphate, triethyl O-acetyl citrate, tributyl O-acetyl citrate, trimethyl O-acetyl citrate, sodium citrate dihydrate, potassium citrate, sodium citrate tribasic trihydrate, sodium citrate tribasic dihydrate, phosphate citrate 등을 들 수 있다. 착물 형성제의 첨가량은 0.1 wt% 내지 30 wt%가 바람직하며, 효과적인 확산방지막 형성을 위해 0.5 wt% 내지 20 wt%를 첨가하는 것이 바람직하다.The complex forming agent is characterized by using a compound containing a citrate of dibasic or tribasic. Examples include ammonium citrate, di-ammonium hydrogen citrate, calcium citrate tribasic tetrahydrate, lithium citrate hydrate, sodium dihydrogen citrate, potassium citrate-1-hydrate, tri-sodium citrate hydrate, sodium citrate, sodium citrate tribasic dihydrate, tributyl citrate, triethyl citrate, trimethyl citrate, citrate phosphate, triethyl O-acetyl citrate, tributyl O-acetyl citrate, trimethyl O-acetyl citrate, sodium citrate dihydrate, potassium citrate, sodium citrate tribasic trihydrate, sodium citrate tribasic dihydrate, phosphate citrate . The addition amount of the complex forming agent is preferably 0.1 wt% to 30 wt%, and 0.5 wt% to 20 wt% is preferably added for effective diffusion barrier film formation.
하부 및 상부 확산방지막의 형성 속도를 높이기 위해 상기 무전해 도금용액은 40℃ 내지 90℃로 유지되어야 하며, 적절한 무전해 도금의 속도를 고려할 때 60℃ 내지 80℃로 유지되는 것이 바람직하나 실제 적용되는 환경에 따라 다양한 조건에서 진행될 수 있다.In order to increase the formation rate of the lower and upper diffusion barriers, the electroless plating solution should be maintained at 40 ° C to 90 ° C. Depending on the environment, it can be carried out under various conditions.
[실시예][Example]
Si 기판 위에 습식산화(wet oxidation)를 통해 10000Å 두께의 실리콘 산화물층(silicon oxide)을 성장시킨 후, 상기 실리콘 산화물층에 PVD를 사용하여 Ta과 TaN층을 순차적으로 각각 500Å과 300Å의 두께만큼 형성시켰다. 그리고 상기 TaN층 상에 PVD를 통해 9000Å 두께의 구리막을 형성시켰다. After 10000 100 thick silicon oxide was grown on the Si substrate by wet oxidation, Ta and TaN layers were sequentially formed with a thickness of 500Å and 300Å by using PVD on the silicon oxide layer, respectively. I was. A copper film having a thickness of 9000 막 was formed on the TaN layer through PVD.
그리고 무전해 도금을 통하여 상기 구리막 상에 하부 확산방지막으로서 CoWP층을, 상부 확산방지막으로서 CoB층을 형성하여 CoB/CoWP/Cu 구조를 완성하였다. 표 1은 하부 확산방지막의 형성에 사용되는 무전해 도금 용액의 조성을 나타낸 것이고, 표 2는 상부 확산방지막의 형성에 사용되는 무전해 도금 용액의 조성을 나타낸 것이다. 무전해 도금 용액의 온도는 70℃로 유지하였고, pH는 9가 되도록 하였다. A CoWP layer was formed on the copper film as a lower diffusion barrier and a CoB layer was formed on the copper layer through electroless plating to complete a CoB / CoWP / Cu structure. Table 1 shows the composition of the electroless plating solution used for the formation of the lower diffusion barrier, and Table 2 shows the composition of the electroless plating solution used for the formation of the upper diffusion barrier. The temperature of the electroless plating solution was maintained at 70 ° C. and the pH was brought to 9.
[표1. 하부 확산방지막용 무전해 도금 용액(100mL 기준)]Table 1. Electroless Plating Solution for Bottom Diffusion Barrier (100mL)]
[표2. 상부 확산방지막용 무전해 도금 용액(100mL 기준)]Table 2. Electroless Plating Solution for Upper Diffusion Barrier (100mL)]
도 1은 상기 실시예에 따라 형성된 다층 확산방지막의 400℃에서의 산화 저항성을 나타낸 그래프이다. 여기서, 산화도는 공기 중에서의 산화 반응 이후의 박막의 면저항의 변화의 상대값을 나타낸 것으로, 0은 전혀 면저항에 변화가 없는 경우를, 그리고 1은 완전히 산화되어 저항값이 매우 증가한 경우를 의미한다. 산화도의 증가는 산화 실험 후 금속박막의 산화로 인해 저항이 증가함을 의미한다. 단일한 조성을 가지는 확산방지막의 경우, CoB 조성의 박막이 CoWP 조성의 박막에 비해 훨씬 우수한 산화 저항성을 가지는 것으로 나타난다. 1 is a graph showing oxidation resistance at 400 ° C. of a multilayer diffusion barrier film formed according to the embodiment. Here, the degree of oxidation represents the relative value of the sheet resistance change of the thin film after the oxidation reaction in air, where 0 means no change in sheet resistance at all, and 1 means completely oxidized and the resistance value is greatly increased. . Increasing the degree of oxidation means that the resistance increases due to oxidation of the metal thin film after the oxidation experiment. In the case of a diffusion barrier having a single composition, the thin film of CoB composition appears to have much better oxidation resistance than the thin film of CoWP composition.
도 1에서는 상기 실시예에서 얻어지는 CoB/CoWP/Cu 구조 뿐만 아니라, 동일한 조건에서 확산방지막의 형성순서만 달리 하여 얻어지는 CoWP/CoB/Cu 구조에 대해서 종래의 경우와 비교하였다. 도 1에서 알 수 있듯이, CoB/CoWP/Cu 구조를 가지는 박막이 단일한 CoB 구조를 가지는 박막과 거의 유사한 우수한 산화 저항성을 가지며, 또한 CoWP/CoB/Cu의 뒤집힌 구조의 박막에 비해 월등히 우수한 산화 저항성을 가지는 것을 확인할 수 있다.In FIG. 1, not only the CoB / CoWP / Cu structure obtained in the above embodiment, but also the CoWP / CoB / Cu structure obtained by differently forming the diffusion barrier film under the same conditions was compared with the conventional case. As can be seen in FIG. 1, the thin film having the CoB / CoWP / Cu structure has excellent oxidation resistance, which is almost similar to the thin film having the single CoB structure, and the oxidation resistance is much better than that of the inverted thin film of CoWP / CoB / Cu. It can be confirmed that has a.
도 1은 본 발명에 따른 다층 확산방지막의 400℃에서의 산화 저항성을 설명하기 위한 그래프이다. 1 is a graph illustrating the oxidation resistance at 400 ° C. of a multilayer diffusion barrier according to the present invention.
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| US6144099A (en) | 1999-03-30 | 2000-11-07 | Advanced Micro Devices, Inc. | Semiconductor metalization barrier |
| KR20040039591A (en) * | 2002-11-04 | 2004-05-12 | 주식회사 하이닉스반도체 | Method for forming a copper anti-diffusion film and Method for manufacturing a copper metal line using the same |
| KR20060074346A (en) * | 2004-12-27 | 2006-07-03 | 매그나칩 반도체 유한회사 | Method of forming metal interconnect of the semiconductor device |
| US7205233B2 (en) * | 2003-11-07 | 2007-04-17 | Applied Materials, Inc. | Method for forming CoWRe alloys by electroless deposition |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US6144099A (en) | 1999-03-30 | 2000-11-07 | Advanced Micro Devices, Inc. | Semiconductor metalization barrier |
| KR20040039591A (en) * | 2002-11-04 | 2004-05-12 | 주식회사 하이닉스반도체 | Method for forming a copper anti-diffusion film and Method for manufacturing a copper metal line using the same |
| US7205233B2 (en) * | 2003-11-07 | 2007-04-17 | Applied Materials, Inc. | Method for forming CoWRe alloys by electroless deposition |
| KR20060074346A (en) * | 2004-12-27 | 2006-07-03 | 매그나칩 반도체 유한회사 | Method of forming metal interconnect of the semiconductor device |
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