CN101819944A - Method for forming copper contact interconnection structure - Google Patents

Abstract

Translated fromChinese

本发明属于半导体器件技术领域，具体为一种形成铜接触互连结构的方法。具体为，在接触层的介质开孔露出硅片上源漏的金属硅化物层上形成扩散阻挡层，然后进行铜材料的填充，从而形成互连和硅器件的接触。其中扩散阻挡层的材料为含Si的三元金属氮化物，或含C的三元金属氮化物，金属为难熔金属，该扩散阻挡层的电阻率在100-1000Ωcm之间，厚度在2-50纳米之间。本发明可在半导体元件中源漏与互连之间形成高质量的、黏附性好的铜接触互连结构。

The invention belongs to the technical field of semiconductor devices, in particular to a method for forming a copper contact interconnection structure. Specifically, a diffusion barrier layer is formed on the metal silicide layer that exposes the source and drain on the silicon chip through the dielectric opening of the contact layer, and then the copper material is filled to form the interconnection and the contact of the silicon device. The material of the diffusion barrier layer is a ternary metal nitride containing Si, or a ternary metal nitride containing C, the metal is a refractory metal, the resistivity of the diffusion barrier layer is between 100-1000Ωcm, and the thickness is 2-50 between nanometers. The invention can form a copper contact interconnection structure with high quality and good adhesion between the source drain and the interconnection in the semiconductor element.

Description

A kind of method that forms copper contact interconnection structure

Technical field

The invention belongs to technical field of semiconductor device, be specifically related to a kind of method that forms copper contact interconnection structure.

Background technology

Traditional contact layer in the integrated circuit interconnection is filled by tungsten and is formed, but along with further dwindling of device size, the depth-to-width ratio aggravation of more and more littler while of the contact area of tungsten plug, tungsten plug resistance enlarges markedly under this structure, and owing to factors such as the resistivity of tungsten plug own are big, circuit delay is increased, had a strong impact on the speed and the performance of circuit.Adopt the low copper of resistivity can solve the big problem of tungsten plug resistance, can be consistent with copper wiring technique simultaneously, promptly adopt mosaic technology to realize as the contact layer material.

But copper is very easily diffusion in materials such as silicon, nisiloy, has a strong impact on device performance.The copper conductor that is used for copper-connection is all surrounded by diffusion impervious layer usually, to prevent or to slow down its diffusion to greatest extent.And contact layer and the close contact of device source drain region, if adopt copper as the contact layer material, then the diffusion impervious layer performance of copper contact then is crucial.

Requirement to diffusion impervious layer is different because of different structure.Diffusion impervious layer will have good adhesion and close thermal coefficient of expansion with following material layer under the diffusion barrier performance situation of guaranteeing copper, to guarantee the stability of whole system under the heat treatment situation.Be used for being the source drain contact below the diffusion impervious layer of copper contact, be generally metal silicide, be different from the upper copper interconnection structure, therefore need a kind of diffusion impervious layer that the good diffusion barrier properties is arranged on metal silicide.The diffusion impervious layer that is used for copper-connection at present has lot of materials, as silicon nitride, the insoluble metal nitride (TaN, TiN, WN) etc.Author's of the present invention work has been reported at silicide (NiSi) and has been gone up preparation Ta/TaN, structures such as Ru/TaN are as diffusion impervious layer, form the copper contact process, the diffusion barrier performance on metal silicide (as NiSi etc.) can descend to some extent but tantalum nitride is found in experiment.Therefore need a kind of and source drain contact material that the diffusion impervious layer of better coupling is arranged.

Summary of the invention

The object of the present invention is to provide a kind of in semiconductor element the source leak with interconnection between the method for the copper contact interconnection structure that formation is high-quality, adhesion is good.

The present invention proposes method, its step comprises, expose the source at medium holes and leak on the metal silicide surface deposit diffusion impervious layer, adhesion layer/Cu inculating crystal layer successively, and utilize electroplating technology that metal level is filled into window, form needed ground floor contact process after the chemico-mechanical polishing.

In this method, this diffusion barrier material is an emphasis of the present invention.The material of this diffusion impervious layer comprises the ternary metal nitride that contains Si, or contains the ternary metal nitride of C.Wherein metal is a refractory metal, as tantalum, titanium, tungsten etc.The resistivity of this diffusion impervious layer is between 100-1000 μ Ω cm, and thickness is between the 2-50 nanometer.Can utilize physical vapor deposition or atomic layer deposition method to prepare.Above-mentioned ternary metal nitride such as TaSiN, TiSiN, WSiN, TaCN, WCN etc.

Among the present invention, physical vapor deposition comprises and adopts metal Ta or Ti or W target and Si target at Ar/N₂Cosputtering method under the atmosphere, or adopt TaSi, TiSi, WSi alloys target sputtering method.Behind preparation ternary metal nitride, general deposit one deck adhesion layer on this metal nitride, material such as metal Ti, Ta, Ru, Rh, Co, Mo, Pd, Os etc., its thickness is between the 1-20 nanometer.For metal Ru, can directly not have seed crystal Cu thereon and electroplate, and for Ti and Ta material, because its oxidation characteristic, therefore Direct Electroplating copper thereon also need with physical vapor deposition or chemical vapor deposition layer of copper inculating crystal layer again, and thickness is between the 5-100 nanometer.For Ru, Rh, Co, Pd, metals such as Os can directly carry out the electroplating technology of copper.And then with electro-plating method carry out copper the end of from and on fill process.

Description of drawings

Fig. 1, copper contact sample structure schematic diagram.1 is dielectric layer, and 2 is contact hole, and 3 is metal silicide, and 4 is diffusion impervious layer, and 5 is adhesion layer, and 6 is copper seed layer, and 7 is electrodeposited coating.

Fig. 2 (a), the plane copper contact process sample with Cu/Ru/TaSiN/NiSi/Si structure.

Fig. 2 (b), online XRD test spectrum (In-situ XRD), online annealing heating rate is 0.2 ℃/s.Sample structure is respectively Cu (50nm)/Ru (5nm)/TaSiN (10nm)/NiSi (40nm)/Si.

Fig. 3 (a), the plane copper contact process sample with Cu/Ru/TaN/NiSi/Si structure.

Fig. 3 (b), online XRD test spectrum (In-situ XRD), online annealing heating rate is 0.2 ℃/s.Sample structure is respectively Cu (50nm)/Ru (5nm)/TaSiN (10nm)/NiSi (40nm)/Si.

Number in the figure: 1 is dielectric layer, and 2 is contact hole, and 3 is metal silicide, and 4 is diffusion impervious layer, and 5 is adhesion layer, and 6 is copper seed layer, and 7 is electrodeposited coating.

Embodiment

Below in conjunction with accompanying drawing implementation method of the present invention is further described, but the present invention is not limited only to example.

Embodiment 1

1, on metal silicide, adopt TaSiN as the ternary diffusion impervious layer.Utilize the method for magnetron sputtering, be controlled at Ar gas and N in the sputter procedure₂Flow-rate ratio, Ta that sputter is high-purity and Si target.By the sputtering power of control Ta target and Si target, and Ar gas and N in sputter procedure₂Flow-rate ratio, can control the atomic ratio of Ta: Si: N.In sputter procedure, base vacuum is less than 1 * 10^-4Handkerchief.The power of Ta and Si can change to 200W from 50W; Ar: N₂Than changing to 10: 1 from 1: 1; The thickness of film changes to 50 nanometers from 2 nanometers, and this experiment vacuum degree is 2 * 10^-5Handkerchief, Ar operating air pressure are 5 * 10^-1Handkerchief, gas atmosphere is than Ar: N₂=5: 1, about 10 nanometers of TaSiN thickness.The ratio of Ta: Si: N can be regulated by the control sputtering power, and a typical atomic ratio is 1: 0.5: 1.

2, utilize magnetically controlled sputter method deposit Ru adhesion layer on TaSiN, its thickness is in the 1-20 nanometer, and this experiment thickness is about 5 nanometers.

3, at Ru adhesion layer deposit Cu inculating crystal layer, its thickness is in the 5-100 nanometer.The structure (2) that above-mentioned three steps form is seen schematic diagram 2 (a).

4, said structure is immersed in carries out copper in the electroplating solution and electroplate, form the filling of copper product.The structure that forms is seen schematic diagram 1.

5, carry out the copper surface finish with cmp method, be polished to diffusion impervious layer and stop.

6, adopt online XRD to observe the thing phase change of sandwich construction in annealing process, show this Cu/Ru/TaNSi/NiSi structure its Cu in the annealing process in position₃The temperature that Si forms is 650 degree, shown in Fig. 2 (b).

Embodiment 2

1, adopt TaSiN as the ternary diffusion impervious layer in this example.Utilize the atomic layer deposition method.Adopt PDMAT, NH₃And SiH₄As Ta, the first body of N and Si is by control flow, the content of control Ta, N and Si respectively.The temperature of reaction chamber is between the 50-300 degree, and the temperature of PDMAT heating is between the 40-80 degree.Can control film thickness by number of cycles, the thickness of film changes to 10 nanometers from 2 nanometers.The typical atomic ratio of Ta: Si: N is 1: 0.5: 1.

2, utilize the atomic layer deposition method to continue deposit Ru adhesion layer on TaSiN, adopt Ru (EtCp₂) as first body, utilize NH₃As reducing gas.Its thickness is in the 1-20 nanometer.

3, utilize PVD method deposit Cu inculating crystal layer on the Ru adhesion layer, its thickness is in the 5-100 nanometer.

4, said structure is immersed in carries out copper in the electroplating solution and electroplate, form the filling of copper product.

5, carry out the copper surface finish with cmp method, be polished to diffusion impervious layer and stop.

Comparative example 1:

1, on metal silicide, adopt TaN as diffusion impervious layer.Utilize the reactive magnetron sputtering method, be controlled at Ar gas and N in the sputter procedure₂Flow-rate ratio, a TaN atomic ratio of optimizing the TaN material is 1: 1.Thickness is in the 2-50 nanometer.

2, utilize magnetically controlled sputter method deposit Ru adhesion layer on TaN, its thickness is in the 1-20 nanometer.

3, at Ru adhesion layer deposit Cu inculating crystal layer, its thickness is in the 5-100 nanometer.The structure (2) that above-mentioned three steps form is seen schematic diagram 3 (a).

4, said structure is immersed in carries out copper in the electroplating solution and electroplate, form the filling of copper product.Carry out the copper surface finish with cmp method, be polished to diffusion impervious layer and stop.

5, adopt online XRD to observe the thing phase change of sandwich construction (2) in annealing process, show this Cu/Ru/TaNSi/NiSi structure its Cu in the annealing process in position₃The temperature that Si forms is 500 degree, shown in Fig. 3 (b).

Claims (4)

Translated fromChinese

1.一种形成铜接触互连结构的方法，其特征在于具体步骤如下：在介质孔露出源漏金属硅化物表面上依次淀积扩散阻挡层、黏附层/Cu籽晶层，并利用电镀工艺将金属层填进窗口，化学机械抛光后形成所需要的第一层接触工艺；其中，所述扩散阻挡层的材料为含Si的三元金属氮化物，或含C的三元金属氮化物，金属为难熔金属，该扩散阻挡层的电阻率在100-1000μΩ·cm之间，厚度在2-50纳米之间。1. A method for forming a copper contact interconnection structure is characterized in that the specific steps are as follows: a diffusion barrier layer, an adhesion layer/Cu seed layer are deposited sequentially on the surface of the source-drain metal silicide in the dielectric hole, and an electroplating process is used to Fill the metal layer into the window, and form the required first layer contact process after chemical mechanical polishing; wherein, the material of the diffusion barrier layer is a ternary metal nitride containing Si, or a ternary metal nitride containing C, The metal is a refractory metal, the resistivity of the diffusion barrier layer is between 100-1000 μΩ·cm, and the thickness is between 2-50 nanometers.2.根据权利要求1所述的形成铜接触互连结构的方法，其特征在于所述扩散阻挡层的材料为TaSiN、TiSiN、WSiN、TaCN或WCN。2. The method for forming a copper contact interconnection structure according to claim 1, characterized in that the material of the diffusion barrier layer is TaSiN, TiSiN, WSiN, TaCN or WCN.3.根据权利要求1所述的形成铜接触互连结构的方法，其特征在于所述粘附层材料为金属Ti，Ta，Ru，Rh，Co，Mo，Pd，或Os，其厚度在1-20纳米之间。3. The method for forming a copper contact interconnect structure according to claim 1, characterized in that said adhesion layer material is metal Ti, Ta, Ru, Rh, Co, Mo, Pd, or Os, and its thickness is between 1 -20 nm.4.根据权利要求1所述的形成铜接触互连结构的方法，其特征在于所述Cu籽晶层厚度在5-100纳米之间。4. The method for forming a copper contact interconnection structure according to claim 1, characterized in that the thickness of the Cu seed layer is between 5-100 nanometers.

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