Classifications

• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10W—GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
  • H10W20/00—Interconnections in chips, wafers or substrates
  • H10W20/01—Manufacture or treatment
  • H10W20/031—Manufacture or treatment of conductive parts of the interconnections
  • H10W20/032—Manufacture or treatment of conductive parts of the interconnections of conductive barrier, adhesion or liner layers
  • H10W20/033—Manufacture or treatment of conductive parts of the interconnections of conductive barrier, adhesion or liner layers in openings in dielectrics
  • H10W20/035—Manufacture or treatment of conductive parts of the interconnections of conductive barrier, adhesion or liner layers in openings in dielectrics combinations of barrier, adhesion or liner layers, e.g. multi-layered barrier layers
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P14/00—Formation of materials, e.g. in the shape of layers or pillars
  • H10P14/40—Formation of materials, e.g. in the shape of layers or pillars of conductive or resistive materials
  • H10P14/42—Formation of materials, e.g. in the shape of layers or pillars of conductive or resistive materials using a gas or vapour
  • H10P14/43—Chemical deposition, e.g. chemical vapour deposition [CVD]
  • H10P14/432—Chemical deposition, e.g. chemical vapour deposition [CVD] using selective deposition
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10W—GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
  • H10W20/00—Interconnections in chips, wafers or substrates
  • H10W20/40—Interconnections external to wafers or substrates, e.g. back-end-of-line [BEOL] metallisations or vias connecting to gate electrodes
  • H10W20/41—Interconnections external to wafers or substrates, e.g. back-end-of-line [BEOL] metallisations or vias connecting to gate electrodes characterised by their conductive parts
  • H10W20/425—Barrier, adhesion or liner layers
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10W—GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
  • H10W20/00—Interconnections in chips, wafers or substrates
  • H10W20/40—Interconnections external to wafers or substrates, e.g. back-end-of-line [BEOL] metallisations or vias connecting to gate electrodes
  • H10W20/45—Interconnections external to wafers or substrates, e.g. back-end-of-line [BEOL] metallisations or vias connecting to gate electrodes characterised by their insulating parts
  • H10W20/48—Insulating materials thereof

Definitions

• the present invention relates generally to diffusion barriers, and more particularly,
• ALD Atomic layer deposition
• tantalum tantalum nitride (Ta/TaN) bilayer for use as a copper (Cu) diffusion barrier by
• PVD physical vapor deposition
• ALD plasma enhanced ALD
• PE-ALD One possible problem of PE-ALD is the common use of atomic hydrogen (H) as a reducing agent to deposit liner materials.
• H atomic hydrogen
• SiLK is widely known to be reactive with atomic hydrogen (H) such that etching occurs when exposed to atomic hydrogen (H).
• H atomic hydrogen
• TaN tantalum-nitride
• the invention includes methods of depositing a tantalum-nitride (TaN) diffusion barrier region on low-k materials.
• the methods include forming a protective layer on the low-k material substrate by performing plasma-enhanced atomic layer deposition (PE- ALD) from a tantalum-based precursor and a nitrogen plasma in a chamber.
• PE- ALD plasma-enhanced atomic layer deposition
• the protective layer has a nitrogen content greater than its tantalum content.
• a substantially stoich ⁇ ome ⁇ c tantalum-nitride layer is then formed by performing PE-ALD from the tantalum-based precursor and a plasma including hydrogen and nitrogen.
• the invention also includes the tantalum-nitride diffusion barrier region so formed.
• the metal precursor includes tantalum penta-chloride (TaCls).
• TaCls tantalum penta-chloride
• the invention generates a sharp interface between low-k materials and liner materials.
• a copper (Cu) interconnect liner with high nitrogen (N) content that is generated by the invention provides a very stable liner structure to prevent the indiffusion of copper (Cu) into the substrate materials.
• the invention also prevents delamination and intermixing of an underlayer.
• a first aspect of the invention is directed to a method of forming a tantalum- nitride diffusion barrier region on a low-k material substrate, the method comprising the steps of: forming a protective layer on the low-k material substrate by plasma-enhanced atomic layer deposition (PE-ALD) from a tantalum-based precursor and a nitrogen plasma; and forming a subsequent substantially stoichiometric tantalum-nitride diffusion barrier layer by PE-ALD from the tantalum-based precursor and a plasma of hydrogen
• PE-ALD plasma-enhanced atomic layer deposition
• a second aspect of the invention is directed to a method of forming a tantalum- nitride diffusion barrier region on a substrate, the method comprising the steps of: forming a protective layer on the low-k material substrate by conducting a first number of first cycles in a chamber, each first cycle including: exposing the substrate to a tantalum- based precursor, evacuating the chamber, plasma-enhanced atomic layer depositing (PE- ALD) from the tantalum-based precursor and a nitrogen plasma, and evacuating the chamber; and forming a subsequent substantially stoichiometric tantalum-nitride diffusion barrier layer by conducting a second number of second cycles in the chamber, each second cycle including: exposing the substrate to a tantalum-based precursor, evacuating the chamber, PE-ALD from the tantalum-based precursor and a plasma of hydrogen and nitrogen, and evacuating the chamber.
• PE- ALD plasma-enhanced atomic layer depositing
• a third aspect of the invention is directed to a tantalum-nitride diffusion barrier region for use with a low-k material, the layer comprising: a protective layer adjacent the low-k material, the protective layer including a tantalum-nitride material having a nitrogen content greater than a tantalum content; and a substantially stoichiometric tantalum-nitride diffusion barrier layer adjacent the protective layer.
• FIG. 1 shows a schematic cross-section view of a tantalum-nitride diffusion barrier region according to the invention.
• FIG.2 shows a flow diagram of a method for generating the TaN diffusion barrier region according to the invention.
• FIG. 3 shows a XRD spectrum for a high nitrogen TaN protective layer created by the method of FIG. 2.
• FIG.4 shows light scatter and sheet resistance graphs for the high nitrogen TaN protective layer during thermal annealing.
• FIGS.5A-5B show transmission electron microscope images of diffusion barrier layer samples.
• FIGS.6A-6B show micro energy dispersed x-ray (EDX) data graphs for the diffusion barrier region samples of FIGS. 5A-5B.
• EDX micro energy dispersed x-ray
• FIG. 1 illustrates a tantalum-nitride (TaN) diffusion barrier region 100 for use with a low-k material 102 according to the invention.
• Barrier region 100 includes: a protective layer 104 including a TaN material having a nitrogen content greater than a tantalum content adjacent low-k material 102; and a subsequent substantially stoichiometric TaN diffusion barrier layer 108 adjacent to protective layer 106.
• low-k material 102 e.g., SiLK
• protective layer 104 successfully prevents the interaction of atomic hydrogen (H) with the SiLK layer 102 during the later formation of substantially stoichiometric TaN layer 108, and allows layer 108 to be successfully grown even on low-k material (e.g., SiLK) 102.
• FIG. 2 a flow diagram of a method of forming a high nitrogen TaN protective layer 104 and substantially stoichiometric TaN diffusion barrier using plasma- enhanced atomic layer deposition (PE-ALD) according to the invention is shown. It should be recognized that the invention will be described relative to one illustrative application of the methods to a sample.
• PE-ALD plasma- enhanced atomic layer deposition
• the method includes repeating a number of cycles as would be expected for a PE-ALD technique.
• the method is carried out in a noncommercial ALD chamber capable of handling sample sizes as large as 200 mm diameter.
• the chamber may include a reactive-gas grade turbo molecular pump with a working base pressure of 10 "7 Torr.
• Sample heating may be conducted using a ceramic resistive heating plate, which provides growth temperatures up to 450°C. The method, in one embodiment, runs at approximately 300°C.
• protective layer 104 (FIG. 1) is formed on low-k material substrate 102 (FIG. 1) by PE-ALD from a tantalum-based precursor and a nitrogen plasma.
• the substrate is exposed to a tantalum-based precursor.
• tantalum pentaiodide Ti 5
• tantalum pentafluoride TiF 5
• tantalum pentabromide TaBr 5
• the glass tube may be maintained at a temperature, e.g., 90°C, to develop adequate vapor pressure.
• delivery lines may be heated between 90-110°C to prohibit condensation of the precursor.
• a carrier gas including, e.g., argon (Ar), maybe used, the flow of which may be controlled by a mass flow controller upstream from the source tube.
• the substrate is exposed to > 1000 Langmuirs (L) of TaCl 5 carried by Ar gas.
• a Langmuir equals exposure for 1 s at 10 "6 Torr.
• Substrates upon which the method may be implemented include any low-k material such as: silicon dioxide (SiO ), hydro-fluoric (HF) dipped silicon (Si), and a low-k dielectric material such as SiLK on silicon dioxide (SiO 2 ).
• the chamber may be evacuated, e.g., using an evacuation pump.
• no purging gas is used between metal precursor and plasma exposure (step S 1 C or step S2C below).
• a purging gas may be used, which should not change the result of the method.
• the substrate is exposed to nitrogen plasma.
• a gate valve fbr nitrogen is opened for a radio frequency (RF) source.
• the RF plasma source may be any conventional plasma source including, for example, a quartz tube wrapped with copper (Cu) coil for producing the plasma.
• PE-ALD from the tantalum-based precursor in the nitrogen plasma (without hydrogen) results in formation of TaN protective layer 104 (FIG. 1) having a higher nitrogen content than tantalum, the benefits of which will be described below.
• step SID the chamber may be evacuated again and one cycle of PE-ALD to form protective layer 104 (FIG. 1) is completed. As shown in FIG.2, step SI may be repeated for a number of cycles, which determines the thickness of protective layer 104 (FIG. 1).
• step S2 subsequent substantially stoichiometric TaN diffusion barrier layer 108 (FIG. 1) is formed by PE-ALD from the tantalum-based precursor and a plasma of hydrogen and nitrogen.
• Steps S2A-S2D represent a repeating of steps S1A-S1D with a change in the plasma to include hydrogen and nitrogen.
• a gate valve for hydrogen and nitrogen is opened for a radio frequency (RF) source.
• RF radio frequency
• a balance between tantalum and nitride content in TaN diffusion barrier layer 108 (FIG. 1) is controlled by controlling the flows of nitrogen (N) and/or hydrogen (H) via one or more leak valves.
• step S2 may be repeated for a number of cycles, which determines the thickness of the substantially stoichiometric TaN diffusion barrier layer 108 (FIG. 1).
• the number of cycles of protective layer 104 (FIG. 1) formation is less than the number of cycles in which the substantially stoichiometric TaN layer 108 (FIG. 1) is formed, i.e., the substantially stoichiometric TaN layer is thicker.
• the number of cycles employed was 100 cycles for the protective layer and 800 cycles for substantially stoichiometric TaN diffusion barrier layer.
• FIG. 1 To illustrate the physical properties of protective layer 104 (FIG. 1), reference is made to FIG. 1 in conjunction with FIGS. 3-4. Referring to FIG.
• an illustrative x-ray diffraction (XRD) spectrum of protective layer 104 deposited using a tantalum-base precursor in the form of TaCl 5 and a nitrogen plasma is shown. Even without atomic H, with only nitrogen plasma, protective layer was deposited.
• RBS analysis has shown that for an illustrative 1200 cycle deposition, 1.360xl0 17 cm 2 of tantalum (Ta) atoms can be deposited with a nitrogen-to-tantalum (N/Ta) ratio of 1.3. While the XRD pattern has been noted to indicate a Ta 3 N 5 phase, other high nitrogen content TaN x phases such as Ta N 5 and Ta 5 N 6 may also be present because all these phases have similar XRD peaks.
• the diffraction pattern is very close to the pattern known in the art to be obtained for Ta 3 N 5 phase deposited by tantalum penta-chloride (TaCls) and ammonia (NH 3 ).
• the chloride (Cl) content that was deposited using NH 3 is high at approximately 300°C by about 5 %.
• the Cl content was below 0.5%, which indicates that the efficiency of chloride (Cl) extraction of
• the nitrogen plasma is at least comparable to that of hydrogen plasma.
• protective layer deposited to, for example, about 25 A thickness.
• copper In particular, copper
• thermocouple a K-type thermocouple, which was calibrated using eutectic melting points of various metals in contact with silicon (Si) for an accuracy of ⁇ 3°C.
• a chopped helium-neon (HeNe) laser beam was brought into the annealing chamber through a fiber optic cable and focused through a lens onto the sample surface at an
• lateral length scales of approximately 5 mm and 0.5 mm, respectively.
• This optical scattering technique detects changes in the
• barrier failure may cause (e.g., coexistence of multiple phase composition domains).
• the second in situ technique used was a four-point probe sheet resistance measurement as a function of temperature.
• Four spring-loaded tantalum (Ta) probes arranged approximately in a square geometry maintained contact with the sample surface while 25 mA of current passes through two of the probes, and voltage is measured across the other two. This allowed for a relative sheet resistance measurement that is scaled using a room temperature, absolute measurement made with a fixed in-line four-point probe geometry.
• protective layer 104 has a thermal stability of greater than approximately 820°C, which is a much higher temperature compared to a substantially stoichiometric TaN ALD layer, which fails around 620°C (not shown).
• FIGS. 5A-5B and 6A-6B show the results of number of test analysis on two different samples prepared on SiLK material.
• the samples were prepared by the deposition of ALD TaN x on 150 nm polycrystalline silicon to electrically isolate the silicon substrate during the sheet resistance analysis.
• the first sample (FIGS. 5A and 6A) was prepared using a conventional PE-ALD cubic TaN layer deposition using hydrogen and nitrogen mixture plasma.
• the second sample (FIGS. 5B and 6B) was generated according to the invention.
• the method included protective layer formation (nitrogen-only plasma) for 100 cycles followed by a substantially stoichiometric TaN layer formation (hydrogen and/or nitrogen) for 800 cycles.
• TEM Analytical transmission electron microscopy
• FIG. 5A shows TEM analysis of deposition of tantalum-nitride on low-k material (e.g., SiLK) according to the prior art approach
• FIG. 5B shows TEM analysis of deposition of TaN x on low-k material (e.g., SiLK) according to the present invention.
• low-k materials such as SiLK are vulnerable when exposed to atomic H during plasma deposition.
• FIG. 5 A illustrates the results of a hydrogen plasma to deposit substantially stoichiometric TaN layer 10 on SiLK layer 12. After deposition for 800 cycles, macroscopic delamination is observed for the films, resulting from the reactivity of SiLK with the hydrogen plasma. In particular, the interface is very rough between TaN layer 10 and SiLK layer 12, and mixing is clearly visible.
• FIG. 5B illustrates a TEM image of a second sample that was prepared
• low-k material 102 e.g., S ⁇ LK
• protective layer 104 resulting in a very-k
• FIGS. 6A-6B illustrate micro energy dispersed x-ray (EDX) data that has been obtained for the samples shown in FIGS.5A-5B, respectively.
• EDX micro energy dispersed x-ray
• FIG. 6A the conventional tantalum (Ta) profile shows severe intermixing and the interface is very diffuse.
• FIG. 6B shows the tantalum (Ta) profile generated by the present invention in which the profile shows very little, if any, intermixing and a very smooth interface.

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• Chemical Vapour Deposition (AREA)
• Internal Circuitry In Semiconductor Integrated Circuit Devices (AREA)
• Electrodes Of Semiconductors (AREA)

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• 2004
  • 2004-06-02 US US10/709,865 patent/US7211507B2/en not_active Expired - Lifetime
• 2005
  • 2005-05-30 TW TW094117722A patent/TWI345273B/zh not_active IP Right Cessation
  • 2005-05-31 JP JP2007515460A patent/JP4791456B2/ja not_active Expired - Fee Related
  • 2005-05-31 EP EP05755089.9A patent/EP1756856B1/en not_active Expired - Lifetime
  • 2005-05-31 WO PCT/US2005/018953 patent/WO2005122253A2/en not_active Ceased
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