KR100752504B1 - Fabrication Method of Metal Interconnection by Electroless Plating - Google Patents
Fabrication Method of Metal Interconnection by Electroless Plating Download PDFInfo
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- KR100752504B1 KR100752504B1 KR1020040106239A KR20040106239A KR100752504B1 KR 100752504 B1 KR100752504 B1 KR 100752504B1 KR 1020040106239 A KR1020040106239 A KR 1020040106239A KR 20040106239 A KR20040106239 A KR 20040106239A KR 100752504 B1 KR100752504 B1 KR 100752504B1
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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
- C23C18/38—Coating with copper
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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
- C23C18/1655—Process features
- C23C18/1664—Process features with additional means during the plating process
- C23C18/1669—Agitation, e.g. air introduction
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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
- C23C18/168—Control of temperature, e.g. temperature of bath, substrate
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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
- C23C18/38—Coating with copper
- C23C18/40—Coating with copper using reducing agents
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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
- C23C18/38—Coating with copper
- C23C18/40—Coating with copper using reducing agents
- C23C18/405—Formaldehyde
Abstract
본 발명은 무전해 도금을 이용하여 패턴 내 금속배선을 형성하는 방법에 관한 것으로, 1차 시드층 형성시 코발트 또는 포름알데히드를 환원제로 사용하여 구리 무전해 도금용액에서 얇고 균일한 시드층을 형성하는 단계와, 디시아옥탄디술폰산(4,5-dithiaoctane-1,8-disulfonic acid) 또는 멀캡토프로판술포네이트 (3-mercapto-1-propanesulfonate)를 첨가제로 사용하여 bottom-up filling 방식으로 패턴을 금속으로 채우는 단계를 포함하여 이루어지며, 본 발명에 의한 무전해 도금을 이용한 패턴 내 금속배선 형성방법은 금속 배선의 표면 거칠기를 감소시키고 막질을 향상시키며, 보이드(void)나 씸(seam)과 같은 결점이 없이 bottom-up filling 방식으로 채워 범프(bump)를 형성시킬 수 있는 효과가 있다.The present invention relates to a method for forming a metal wiring in a pattern using an electroless plating, and to form a thin and uniform seed layer in a copper electroless plating solution using cobalt or formaldehyde as a reducing agent when forming the primary seed layer. And a pattern by bottom-up filling method using dimerethane octasulfonic acid (4,5-dithiaoctane-1,8-disulfonic acid) or mercaptopropanesulfonate (3-mercapto-1-propanesulfonate) as an additive. It comprises a step of filling with a metal, the method of forming a metal wiring in the pattern using the electroless plating according to the present invention to reduce the surface roughness of the metal wiring and improve the film quality, such as voids (seam) There is an effect that can form a bump (bump) by filling the bottom-up filling method without a defect.
무전해 도금, 디시아옥탄디술폰산(4,5-dithiaoctane-1,8-disulfonic acid), 멀캡토프로판술포네이트 (3-mercapto-1-propanesulfonate), SPS, MPSA, 보이드(void), 씸(seam), bottom-up filling, 범프(bump)Electroless Plating, 4,5-dithiaoctane-1,8-disulfonic acid, 3-mercapto-1-propanesulfonate, SPS, MPSA, void, 씸 ( seam, bottom-up filling, bump
Description
도 1은 첨가제를 이용하여 패턴을 채우는 과정을 나타낸 모식도이다.1 is a schematic diagram showing a process of filling a pattern using an additive.
도 2은 확산방지막 위에 팔라듐(Palladium)으로 활성화(activation) 시킨 뒤 코발트(Co)를 환원제로 사용한 무전해 도금으로 시드층을 형성한 패턴의 단면도이다.FIG. 2 is a cross-sectional view of a pattern in which a seed layer is formed by electroless plating using cobalt (Co) as a reducing agent after activation with palladium on a diffusion barrier.
도 3은 도 2에서 형성한 시드층을 가진 패턴을 상온에서 디시아옥탄디술폰산(4,5-dithiaoctane-1,8-disulfonic acid)(이하 SPS라 함)를 첨가한 구리 무전해 도금 용액을 이용하여 채운 단면을 시간별로 나타낸 사진이다. FIG. 3 shows a copper electroless plating solution in which a pattern having a seed layer formed in FIG. 2 is added with dithiaoctane disulfonic acid (4,5-dithiaoctane-1,8-disulfonic acid) (hereinafter referred to as SPS) at room temperature. It is a photograph showing the cross-section filled by time.
도 4는 확산방지막 위에 팔라듐으로 활성화 시킨 뒤 포름알데히드를 환원제로 사용한 무전해 도금으로 시드층을 형성한 뒤, 상온에서 SPS를 첨가한 구리 무전해 도금 용액을 이용하여 채운 단면을 나타낸 사진이다.Figure 4 is a photograph showing a cross-section using a copper electroless plating solution added with SPS at room temperature after forming a seed layer by electroless plating using formaldehyde as a reducing agent after activating with a palladium on the diffusion barrier.
도 5는 1차 구리 시드층을 패턴을 채움에 있어서 전착 온도를 50도로 한 결과를 나타낸 사진이다.5 is a photograph showing a result of electrodeposition temperature of 50 degrees in filling the primary copper seed layer with a pattern.
도 6은 1차 구리 시드층이 형성된 패턴을 채움에 있어서 전착 온도를 70도로 하고 SPS와 함께 2,2'-dipyridyl을 첨가하여 막질을 개선한 결과를 나타낸 사진이다. Figure 6 is a photograph showing the result of improving the film quality by adding the 2,2'-dipyridyl with the SPS and the electrodeposition temperature in filling the pattern formed with the primary copper seed layer.
도 7은 건식법(PVD)에 의한 방법으로 구리 시드층을 형성시킨 기판에 패턴 채움을 실시한 결과를 나타낸 사진이다. 7 is a photograph showing a result of pattern filling on a substrate on which a copper seed layer is formed by a dry method (PVD).
본 발명은 무전해 도금을 이용한 패턴 내 금속배선 형성방법에 관한 것이다. 더욱 상세하게는, 1차 시드층 형성시 코발트를 환원제로 사용하여 구리 무전해 도금용액에서 얇고 균일한 시드층을 형성하는 단계와, 디시아옥탄디술폰산(4,5-dithiaoctane-1,8-disulfonic acid) 또는 멀캡토프로판술포네이트 (3-mercapto-1-propanesulfonate)를 첨가제로 사용하여 bottom-up filling 방식으로 패턴을 금속으로 채우는 단계를 수행하여 패턴 내 금속배선을 형성하는 방법에 관한 것이다. The present invention relates to a method for forming metal wiring in a pattern using electroless plating. More specifically, forming a thin and uniform seed layer in a copper electroless plating solution using cobalt as a reducing agent when forming the primary seed layer, and dicyoctane disulfonic acid (4,5-dithiaoctane-1,8- The present invention relates to a method of forming metal wiring in a pattern by performing a step of filling the pattern with a metal by a bottom-up filling method using disulfonic acid) or mercapto-1-propanesulfonate as an additive.
반도체 배선에서 구리막의 형성공정은 기존의 알루미늄 공정을 대체하여 차세대 로직칩(logic chip)과 디램(DRAM) 등의 성능을 향상시키기 위해 중요한 역할을 하는 것으로 인식되고 있다. 특히, PVD나 CVD와 같은 건식법 이외에 전해도금, 무전해 도금과 같은 전기화학적인 구리 형성 방법은 다마신 공정을 위한 핵심 기술로 여겨지고 있다. The process of forming a copper film in semiconductor wiring has been recognized to play an important role in improving performance of next-generation logic chips and DRAMs, replacing the existing aluminum process. In particular, in addition to dry methods such as PVD and CVD, electrochemical copper formation methods such as electroplating and electroless plating are considered to be key technologies for the damascene process.
일반적인 구리 전해도금 방식은 확산방지막 위에 얇은 시드층을 건식 또는 습식법으로 형성한 후, 첨가제를 이용하여 보이드(void)나 씸(seam)과 같은 결함(defect)가 없이 패턴을 채우는 방식의 연구가 이루어져 왔다. The general copper electroplating method is a method of forming a thin seed layer on the diffusion barrier layer by dry or wet method, and then filling the pattern without defects such as voids or seams using additives. come.
무전해 도금의 경우, 낮은 증착속도와 컨포멀(conformal)한 형태의 구리막 형성으로 인해 전해도금을 위한 시드층 형성과 같은 응용분야로 연구가 이루어져 왔으며, 무전해 도금만을 이용한 패턴 채움에 관한 연구는 부족한 실정이다. In the case of electroless plating, research has been conducted into application fields such as seed layer formation for electroplating due to the low deposition rate and conformal copper film formation, and pattern filling using only electroless plating. Is not enough.
무전해 도금은 용액 내에서 환원제가 산화하면서 발생한 전자를 이용해 금속 이온을 환원시키는 방법으로, 확산방지막과 같은 기판 위에서 무전해 도금을 하기 위해서는, 팔라듐, 구리, 은, 금과 같은 촉매를 이용하여 기판표면을 활성화시켜야 한다. 그 뒤에 촉매로 활성화된 기판을 금속이온, 환원제, 착화제, 첨가제, pH 조절제 등으로 구성되어 있는 무전해 도금 용액에 담지하여 무전해 도금을 완성하게 된다. Electroless plating is a method of reducing metal ions using electrons generated by oxidation of a reducing agent in a solution. In order to electroless plate on a substrate such as a diffusion barrier, a substrate such as palladium, copper, silver, and gold is used. The surface must be activated. Subsequently, the substrate activated by the catalyst is supported on an electroless plating solution composed of metal ions, reducing agents, complexing agents, additives, pH adjusting agents, and the like to complete the electroless plating.
첨가제는 금속이온과의 결합을 통해 착화합물을 형성시켜 용액 내에서 금속을 안정화시키는 안정제(stabilizer)나 표면장력을 감소시키고 환원제의 탈수소화 (dehydrogenation)반응을 통한 무전해 도금에서 발생되는 수소와 같은 부산물을 효과적으로 제거 시켜주는 표면활성제(surfactant), SPS, MPSA와 같이 박막 형성 속도를 빠르게 하는 촉진제(accelerator)등이 있다. 특히, SPS나 MPSA와 같은 촉진제는 패턴을 보이드(void)나 씸(seam)없이 채울 수 있도록 도와준다. 하지만, 이를 사용하였을 때 표면의 거칠기와 막질이 떨어지는 문제점이 있었다.Additives are stabilizers that stabilize complex metals in combination with metal ions to reduce the surface tension, and by-products such as hydrogen from electroless plating through dehydrogenation of the reducing agent. Surfactants, SPS, MPSA, etc., which effectively remove the active material, such as accelerators (accelerator) to speed up the formation of thin films. In particular, accelerators such as SPS and MPSA help to fill the pattern without voids or seams. However, when using this, there was a problem that the surface roughness and film quality fall.
상기와 같은 문제점을 해결하기 위하여 본 발명은, 무전해 도금에서 SPS나 MPSA와 같은 촉진제를 사용하여 패턴을 금속으로 채움에 있어서 표면의 거칠기와 막질을 향상시키기 위해서 1차 시드층을 형성하는 단계에서 얇고 균일한 막을 형성하고, 또한 2차 구리패턴 채움 단계에 있어서 온도를 조절하거나 첨가제를 넣어 막 질을 향상시키고, 막 형성 속도를 제어할 수 있도록 한 무전해 도금을 이용한 패턴 내 금속배선 형성방법을 제공하는 것을 목적으로 한다.In order to solve the above problems, the present invention, in the step of forming the primary seed layer to improve the surface roughness and film quality in filling the pattern with a metal using an accelerator such as SPS or MPSA in electroless plating A method of forming a metal wiring in a pattern using electroless plating to form a thin and uniform film and to control the temperature or add an additive to improve the film quality and to control the film formation rate in the secondary copper pattern filling step It aims to provide.
본 발명의 상기 목적 및 기타 목적들은 하기 설명되는 본 발명에 의하여 모두 달성될 수 있다. The above and other objects of the present invention can be achieved by the present invention described below.
상기 목적을 달성하기 위하여, 본 발명은In order to achieve the above object, the present invention
패턴이 형성된 기판을 첨가제가 함유되지 않은 구리 무전해 도금 용액에서 코발트를 환원제로 사용하여 습식법으로 1차 구리 무전해 도금을 실시하여 시드층을 형성하는 제1단계; 및 상기 제1단계를 거친 기판을 첨가제가 함유된 구리 무전해 도금 용액에 침지하여 2차로 패턴을 채우는 제2단계;를 포함하여 이루어지는 것을 특징으로 하는 무전해 도금을 이용한 패턴 내 금속배선 형성방법을 제공한다.A first step of forming a seed layer by performing a primary copper electroless plating by a wet method using cobalt as a reducing agent in a copper electroless plating solution containing no pattern on an additive-containing substrate; And a second step of immersing the substrate subjected to the first step in a copper electroless plating solution containing an additive to fill a pattern in a second manner. The method for forming metal wirings in a pattern using an electroless plating, comprising: to provide.
상기 첨가제는 디시아옥탄디술폰산(4,5-dithiaoctane-1,8-disulfonic acid)(이하 'SPS'라 칭한다) 또는 멀캡토프로판술포네이트(3-mercapto-1-propanesulfonate)(이하 'MPSA'라 칭한다)일 수 있다.The additive may be dicyoctane disulfonic acid (4,5-dithiaoctane-1,8-disulfonic acid) (hereinafter referred to as 'SPS') or mercapto-1-propanesulfonate (hereinafter referred to as 'MPSA'). It may be referred to as).
상기 디시아옥탄디술폰산(SPS)의 농도는 0.2 내지 10 mg/L 이며, 상기 멀캡토프로판술포네이트(MPSA)의 농도는 0.4 내지 20 mg/L 일 수 있다. The concentration of dithiaoctane disulfonic acid (SPS) may be 0.2 to 10 mg / L, and the concentration of mercaptopropanesulfonate (MPSA) may be 0.4 to 20 mg / L.
상기 제2단계의 온도는 15 내지 80℃일 수 있다. The temperature of the second step may be 15 to 80 ℃.
상기 제1단계의 교반 속도는 1 내지 100 rpm 일 수 있다. The stirring speed of the first step may be 1 to 100 rpm.
상기 제2단계에서는 교반을 하지 않을 수 있다. In the second step, the stirring may not be performed.
상기 제1단계는 건식법에 의하여 수행될 수 있다. The first step may be performed by a dry method.
상기 제1단계의 구리 무전해 도금용액은 구리염으로서 0.5 내지 10 g/L 염화구리, 착화제로서 10 내지 80 mL/L 에틸렌디아민, 환원제로서 12 내지 60 g/L 제이질산코발트육수화물, pH 조절제로서 10 내지 50 mL/L의 질산을 포함하여 이루어지며, 구리 무전해 도금용액의 pH는 6 내지 8 일 수 있다. The copper electroless plating solution of the first step is 0.5 to 10 g / L copper chloride as the copper salt, 10 to 80 mL / L ethylenediamine as the complexing agent, 12 to 60 g / L cobalt dinitrate hexahydrate as the reducing agent, pH It comprises 10 to 50 mL / L nitric acid as a regulator, the pH of the copper electroless plating solution may be 6 to 8.
상기 제1단계의 구리 무전해 도금용액은 구리염으로서 5 내지 8 g/L의 황산구리, 착화제로 14 내지 18 g/L 에틸렌디아민사아세트산(EDTA), 환원제로서 2 내지 3.5 g/L 포름알데히드, pH 조절제로서 수산화칼슘 20 내지 35 g/L 를 포함하여 이루어지며, 구리 무전해 도금용액의 pH는 12 내지 14일 수 있다. The copper electroless plating solution of the first step is 5 to 8 g / L copper sulfate as a copper salt, 14 to 18 g / L ethylenediamine tetraacetic acid (EDTA) as a complexing agent, 2 to 3.5 g / L formaldehyde as a reducing agent, Containing calcium hydroxide 20 to 35 g / L as a pH adjusting agent, the pH of the copper electroless plating solution may be 12 to 14.
이하, 본 발명에 대하여 상세히 설명하면 다음과 같다.Hereinafter, the present invention will be described in detail.
본 발명에서는 무전해 도금시 첨가제로 SPS 또는 MPSA를 사용하여 기판에 형성된 패턴에 금속을 채울 때 1차 시드층 형성 단계에서 금속이온의 농도를 희석 또는 전체 용액을 희석하여 증착속도를 줄이고 시드층의 막질을 개선하기 위하여 상온 또는 상온보다 높은 온도에서 무전해 도금을 실시하는 것을 특징으로 한다. In the present invention, when the metal is filled in the pattern formed on the substrate using SPS or MPSA as an additive during electroless plating, the concentration of metal ions or the total solution are diluted in the first seed layer forming step to reduce the deposition rate and In order to improve the film quality, electroless plating is performed at a temperature higher than room temperature.
1차 시드층의 거친 표면은 후속의 2차 패턴 채움 단계에서 증착되는 금속막의 특성에 영향을 미쳐 거친 표면을 유발하고 이는 금속막의 전기적, 기계적 특성을 저하시키기 때문에 얇고 균일한 시드층의 형성은 매우 중요하다 할 수 있다. The rough surface of the primary seed layer influences the properties of the metal film deposited in the subsequent secondary pattern filling step, resulting in a rough surface, which degrades the electrical and mechanical properties of the metal film, thus forming a thin and uniform seed layer. It can be important.
상기 환원제로 사용되는 코발트는, 제이질산코발트육수화물, 제이염화코발트육수화물 등이 사용가능하며, 특히 제이질산코발트육수화물이 바람직하다. 상기 환원제는 에틸렌디아민과 착화합물을 이루어 환원제 역할을 한다.As the cobalt used as the reducing agent, cobalt dinitrate hexahydrate, cobalt dichloride hexahydrate and the like can be used, and cobalt dinitrate hexahydrate is particularly preferable. The reducing agent forms a complex with ethylenediamine to serve as a reducing agent.
상기 제1단계는 습식법 또는 PVD 또는 CVD와 같은 건식법에 의하여 수행될 수 있다. 만일 습식법에 의하여 수행되는 경우에는, 교반을 하지 않거나, 100rpm의 속도에서 수행하는 것이 바람직하다. 만일 100rpm을 초과하는 경우에는 막이 너무 두꺼워 지는 문제점이 발생하게 된다.The first step may be performed by a wet method or a dry method such as PVD or CVD. If it is carried out by the wet method, it is preferable to perform no stirring or at a speed of 100 rpm. If it exceeds 100rpm, the film becomes too thick.
상기 첨가제는 디시아옥탄디술폰산(4,5-dithiaoctane-1,8-disulfonic acid)(SPS), SPS의 단량체(monomer)인 멀캡토프로판술포네이트(3-mercapto-1-propanesulfonate)(MPSA), 디피에스(N,N-Dimethyl dithiocarbamic acid (3-sulfopropyl) ester)(DPS)이 사용될 수 있으며, 이들은 박막형성 속도를 촉진하는 역할을 한다. 바람직하게는 SPS 또는 MPSA가 좋다.The additive is dimethyl octadisulfonic acid (4,5-dithiaoctane-1,8-disulfonic acid) (SPS), the monomer of the SPS (mermer) (3-mercapto-1-propanesulfonate) (MPSA) N, N-Dimethyl dithiocarbamic acid (3-sulfopropyl) ester (DPS) may be used, and these may promote the formation rate of the thin film. Preferably SPS or MPSA is preferred.
상기 SPS의 농도는 0.2 내지 10 mg/L가 바람직하다. 만일 SPS의 농도가 0.2 mg/L 미만인 경우에는 가속효과가 나타나기 힘들고, 10 mg/L를 초과하는 경우에는 억제효과가 나타나 구리의 환원을 막는다. 또한 상기 MPSA의 농도는 0.4 내지 20 mg/L가 바람직하며, 만일 MPSA의 농도가 0.4 mg/L 미만인 경우에는 가속효과가 나타나기 힘들고, 20 mg/L를 초과하는 경우에는 억제효과가 나타나 구리의 환원을 막는다. The concentration of SPS is preferably 0.2 to 10 mg / L. If the concentration of SPS is less than 0.2 mg / L, it is difficult to show an acceleration effect, when it exceeds 10 mg / L to suppress the reduction of copper. In addition, the concentration of MPSA is preferably 0.4 to 20 mg / L, and if the concentration of MPSA is less than 0.4 mg / L, the acceleration effect is less likely to occur. To prevent.
상기 제1단계는 반응온도 15∼70℃에서 수행되는 것이 바람직하며, 제2단계는 15∼80℃에서 수행되는 것이 바람직하다. 상기 온도범위를 미달하는 경우에는 표면이 거칠고 막 내부에 불순물이 포함되며, 상기 온도범위를 초과하는 경우 용액의 안정성이 떨어지게 된다.The first step is preferably carried out at a reaction temperature of 15 to 70 ℃, the second step is preferably carried out at 15 to 80 ℃. When the temperature is below the temperature range, the surface is rough and impurities are contained in the film, and when the temperature is exceeded, the stability of the solution is deteriorated.
상기 제1단계에서의 구리 무전해 도금용액은 구리염으로서 0.5 내지 10 g/L 염화구리, 착화제로서 10 내지 80 mL/L 에틸렌디아민, 환원제로서 12 내지 60 g/L 제이질산코발트육수화물, pH 조절제로서 10 내지 50 mL/L의 질산을 포함하는 것이 바람직하다. 또한 용액의 pH는 6 내지 8 인 것이 좋다. 용액의 pH가 6보다 낮을 때는 균일한 막의 형성이 어려우며, 8보다 높을 경우 불순물의 함유가 많으며 비저항이 증가한다. 상기 용액은 전체를 희석하여 사용하거나, 특정성분을 희석하여 사용하는 것도 가능하다. The copper electroless plating solution in the first step is 0.5 to 10 g / L copper chloride as the copper salt, 10 to 80 mL / L ethylenediamine as the complexing agent, 12 to 60 g / L cobalt nitrate hexahydrate as the reducing agent, Preference is given to including 10-50 mL / L nitric acid as the pH adjusting agent. In addition, the pH of the solution is preferably 6 to 8. When the pH of the solution is lower than 6, it is difficult to form a uniform film. When the pH is higher than 8, the content of impurities is high and the resistivity increases. The solution may be used by diluting the whole, or by diluting a specific component.
상기 제 1단계에서의 구리 무전해 도금용액은 또한, 구리염으로서 5 내지 8 g/L의 황산구리, 착화제로 14 내지 18 g/L 에틸렌디아민사아세트산(EDTA), 환원제로서 2 내지 3.5 g/L 포름알데히드, pH 조절제로서 수산화칼슘 20 내지 35 g/L 를 포함한 것을 pH 12 내지 14 의 범위에서 사용할 수 있다. 또한 이 용액에 SPS 0.2∼10 mg/L 또는 MPSA 0.4∼20mg/L를 첨가하여 제2단계의 구리 무전해 도금용액으로 사용할 수 있다.The copper electroless plating solution in the first step is also 5 to 8 g / L copper sulfate as the copper salt, 14 to 18 g / L ethylenediamine tetraacetic acid (EDTA) as the complexing agent, 2 to 3.5 g / L as the reducing agent Formaldehyde, those containing 20 to 35 g / L calcium hydroxide as the pH adjusting agent can be used in the range of pH 12 to 14. In addition, 0.2 to 10 mg / L of SPS or 0.4 to 20 mg / L of MPSA can be added to this solution to be used as the copper electroless plating solution of the second step.
2차 패턴 채움 단계에서 구리의 막질을 개선하기 위하여, SPS나 MPSA와 함께 0.1 mg/L 내지 1 g/L의 2,2'-dipyridyl을 첨가할 수 있다. 이 때, 함께 첨가하는 SPS의 농도는 0.02∼10 mg/L, MPSA는 0.04∼20 mg/L 이어야 한다. In order to improve the film quality of copper in the second pattern filling step, 0.1 mg / L to 1 g / L of 2,2'-dipyridyl may be added together with SPS or MPSA. At this time, the concentration of SPS added together should be 0.02 to 10 mg / L, and MPSA should be 0.04 to 20 mg / L.
상기 기판의 확산방지막 층이 TiN, Pd로 활성화(activation)된 Ta 또는 TaN로 형성될 수 있다.The diffusion barrier layer of the substrate may be formed of Ta or TaN activated with TiN, Pd.
이하, 하기의 실시예를 통하여 본 발명을 더욱 상세히 설명하지만, 본 발명의 범위가 실시예에 한정되는 것은 아니다.Hereinafter, the present invention will be described in more detail with reference to the following examples, but the scope of the present invention is not limited to the examples.
구리 무전해 도금을 하기 위한 기판으로는 실리콘 웨이퍼 상에 15 nm 두께의 티타늄 및 10 nm 두께의 질화티타늄을 확산방지막으로 형성한 질화티타늄/티타늄/ 실리콘 구조를 사용하였다. As a substrate for copper electroless plating, a titanium nitride / titanium / silicon structure in which 15 nm thick titanium and 10 nm titanium nitride were formed as a diffusion barrier on a silicon wafer was used.
[실시예 1]Example 1
구리 무전해 도금을 이용하여 시드층을 형성시키기 위해 먼저, 표면의 자연산화막인 산화 티타늄막을 불산 및 이온제거수(De-Ionized Water)로 이루어진 1% 불산 용액에 10분간 침지시킨 후, 이온제거수에서 잔류물을 제거했다. 그 다음, 기판 표면을 이온제거수 200 mL에 염화팔라듐 (PdCl2) 1 g, 50%의 불산 5mL, 및 35%의 염산(HCl) 3mL가 혼합된 팔라듐 활성화 용액에 20초간 침지시켜 표면을 활성화 시켰다. In order to form a seed layer using copper electroless plating, first, a titanium oxide film, which is a natural oxide film on the surface, is immersed in a 1% hydrofluoric acid solution composed of hydrofluoric acid and de-ionized water for 10 minutes, and then deionized water The residue was removed from. Subsequently, the surface of the substrate was immersed in a palladium activation solution mixed with 200 mL of deionized water and 1 g of palladium chloride (PdCl 2 ), 5 mL of 50% hydrofluoric acid, and 3 mL of 35% hydrochloric acid (HCl) for 20 seconds to activate the surface. I was.
무전해 도금을 통해 1차 시드층을 형성하기 위해 팔라듐으로 표면이 활성화된 기판을 3.4 g/L의 염화구리, 32 mL/L 에틸렌디아민, 환원제로서 35 g/L의 제이질산코발트육수화물, pH조절제로서 26.4 mL/L의 질산이 포함된 무전해 도금용액에서 90초동안 도금하였다. 이때 교반속도는 50rpm로 하였으며, 증착 온도는 상온에서 진행하였다. 이렇게 형성된 시드층은 도 2에서 볼 수 있듯이 패턴에 약 65nm의 균일한 두께로 형성되었다. 3.4 g / L copper chloride, 32 mL / L ethylenediamine, 35 g / L cobalt dinitrate hexahydrate as reducing agent, pH, for palladium surface-activated substrates to form a primary seed layer through electroless plating Plated for 90 seconds in an electroless plating solution containing 26.4 mL / L nitric acid as a regulator. At this time, the stirring speed was 50rpm, and the deposition temperature was performed at room temperature. The seed layer thus formed was formed with a uniform thickness of about 65 nm in the pattern as shown in FIG.
[실시예 2]Example 2
1차로 형성된 시드층에 2 mg/L의 SPS가 포함된 구리무전해 도금용액에서 패턴 채움을 실시하였다. 이때 구리 무전해 도금액은 0.9 g/L 황산구리, 0.41 g/L 포름알데히드, 2.3 g/L 에틸렌디아민사아세트산 (ethylenediaminetetraacetic acid; EDTA), 3.9 g/L 수산화칼륨 등으로 구성하였으며, 패턴 채움이 일어나는 과정을 3, 4, 6, 8, 15분 단위로 촬영하여 이를 도 3에 나타내었다.The seed layer formed primarily was pattern-filled in a copper electroless plating solution containing 2 mg / L SPS. The copper electroless plating solution was composed of 0.9 g / L copper sulfate, 0.41 g / L formaldehyde, 2.3 g / L ethylenediaminetetraacetic acid (EDTA), and 3.9 g / L potassium hydroxide. Was taken in 3, 4, 6, 8, 15 minutes each is shown in Figure 3.
도 3에서 보는 바와 같이 시간에 따라 바닥에서 채움이 일어나는 이른바 bottom-up filling이 일어나는 것을 확인할 수 있었으며, 표면의 거칠기가 하기의 비교 예에서 보인 것보다 감소함을 확인할 수 있었다.As shown in Figure 3 it was confirmed that the so-called bottom-up filling occurs in the bottom over time, the surface roughness was confirmed to decrease than shown in the comparative example below.
[비교예 1]Comparative Example 1
팔라듐으로 활성화된 질화 티타늄 기판에 1차 시드층을 형성하기 위해 0.9 g /L 황산구리, 0.41 g/L 포름알데히드, 2.3 g/L 에틸렌디아민사아세트산, 3.9 g/L 수산화칼륨으로 이루어진 무전해 도금에 90초간 담지하였다.(도 4 좌측) 그 뒤에 같은 성분과 농도로 이루어진 구리 무전해 도금 용액에 2 mg/L의 SPS을 첨가하여 패턴 채움을 실시하였다. 그 결과 도 4의 우측사진에서 보는 바와 같이 표면이 매우 거침을 알 수 있었다.Electroless plating consisting of 0.9 g / L copper sulfate, 0.41 g / L formaldehyde, 2.3 g / L ethylenediaminetetraacetic acid and 3.9 g / L potassium hydroxide to form a primary seed layer on a palladium-activated titanium nitride substrate It was supported for 90 seconds (left of FIG. 4). Then, pattern filling was performed by adding 2 mg / L of SPS to a copper electroless plating solution having the same components and concentrations. As a result, as shown in the right picture of Fig. 4, the surface was found to be very rough.
[실시예 3]Example 3
실시예 1에서와 같이 형성된 1차 구리 시드층을 실시예 2에서 보인 바와 같이 패턴을 채움에 있어서 증착 온도를 50도로 하여 1, 3, 6, 10분 간격으로 이를 촬영하여 도 5에 나타내었다.As shown in Example 2, the primary copper seed layer formed as in Example 1 was photographed at intervals of 1, 3, 6, and 10 minutes at a deposition temperature of 50 degrees, and is shown in FIG. 5.
그 결과, 도 5에서 보는 바와 같이 표면이 더욱 개선되었으며 완전히 패턴을 채운 후에 가속제를 이용한 bottom-up filling의 흔적을 알 수 있는 범프(bump)가 생긴 것을 확인할 수 있었다. 또한, 50도에서 증착속도는 상온과 비교했을 때 증가한 것을 확인할 수 있었다. As a result, as shown in FIG. 5, the surface was further improved, and after the pattern was completely filled, it was confirmed that a bump was generated in which a trace of bottom-up filling using an accelerator was found. In addition, the deposition rate at 50 degrees was confirmed to increase compared to room temperature.
[실시예 4] Example 4
실시예 1에서와 같이 형성된 1차 구리 시드층을 실시예 2에서 보인 바와 같이 패턴을 채움에 있어서 증착 온도를 70도로 하고 SPS와 함께 2,2'-dipyridyl을 첨가하여 막질을 개선하였다. 도 6에서 보는 바와 같이, 표면이 더욱 개선되었으며 완전히 패턴을 채운 후에 가속제를 이용한 bottom-up filling의 흔적을 알 수 있는 범프(bump)가 생긴 것을 확인할 수 있었다. As shown in Example 2, the primary copper seed layer formed as in Example 1 was deposited with a deposition temperature of 70 degrees and 2,2'-dipyridyl was added with SPS to improve the film quality. As shown in FIG. 6, the surface was further improved, and it was confirmed that a bump was generated in which a trace of bottom-up filling using an accelerator was observed after the pattern was completely filled.
[실시예 5] Example 5
SPS의 가속효과 및 패턴 채움 효과가 습식법으로 형성된 구리 시드층 이외에 건식법으로 형성된 시드층에서도 나타나는 지를 확인하기 위해서 PVD 방법으로 구리 시드층을 형성시킨 기판에서 실험을 실시하였다. 먼저 구리 시드의 표면에 있는 자연 산화막을 제거하기 위해 1:200의 비율로 희석된 수산화암모늄(NH4OH)용액에 기판을 30초 동안 침지시킨 후 이온 제거수로 세정하였다. 그 뒤에 이 기판을 실시예 2에서 보인 바와 같이 SPS가 첨가된 구리 무전해 도금 용액에서 패턴 채움을 실시하였다. 그 결과, 도 7에서 보인 바와 같이 씸(seam)이 발생하지 않았다.In order to confirm whether the accelerating effect and the pattern filling effect of SPS appear in the seed layer formed by the dry method in addition to the copper seed layer formed by the wet method, an experiment was performed on the substrate on which the copper seed layer was formed by the PVD method. First, the substrate was immersed in a solution of ammonium hydroxide (NH 4 OH) diluted in a ratio of 1: 200 for 30 seconds to remove the native oxide film on the surface of the copper seed, followed by washing with ion removal water. This substrate was then pattern filled in a copper electroless plating solution with SPS added as shown in Example 2. As a result, no seam occurred as shown in FIG.
이상에서 설명한 바와 같이, 본 발명에 의한 무전해 도금을 이용한 패턴 내 금속배선 형성방법은 SPS나 MPSA와 같은 첨가제를 사용함에 있어 1차 시드층 형성시 코발트를 환원제로 사용한 구리 무전해 도금용액에서 얇고 균일한 시드층을 형성할 수 있었으며, 패턴채움 시 온도를 15 내지 80도로 유지함으로써, 빠른 증착속도로 낮은 표면 거칠기를 갖도록 할 수 있었으며, 습식방법이 아닌 건식법의 시드 층에서도 SPS효과가 나타났으며, 또한, SPS와 함께 2,2'-dipyridyl을 사용하여 채워진 구리의 막질을 상당히 개선시킬 수 있는 효과가 있는 유용한 발명이다.As described above, the method for forming the metal wiring in the pattern using the electroless plating according to the present invention is thin in a copper electroless plating solution using cobalt as a reducing agent when forming the primary seed layer in using an additive such as SPS or MPSA. A uniform seed layer could be formed, and by maintaining the temperature at 15 to 80 degrees during pattern filling, it was possible to have a low surface roughness at a fast deposition rate, and the SPS effect was also observed in the dry seed layer rather than the wet method. In addition, 2,2'-dipyridyl in combination with SPS is a useful invention that has the effect of significantly improving the film quality of the filled copper.
상기에서 본 발명은 기재된 구체예를 중심으로 상세히 설명되었지만, 본 발명의 범주 및 기술사상 범위 내에서 다양한 변형 및 수정이 가능함은 당업자에게 있어서 명백한 것이며, 이러한 변형 및 수정이 첨부된 특허청구범위에 속하는 것도 당연한 것이다.While the invention has been described in detail above with reference to the described embodiments, it will be apparent to those skilled in the art that various modifications and variations are possible within the scope and spirit of the invention, and such modifications and variations fall within the scope of the appended claims. It is also natural.
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