KR19990028026A - Diffusion for Semiconductor Device Wiring Materials - Google Patents

Abstract

The present invention, Ta / M / Ta (M is W, Zr, Nb and V by the ion beam assisted deposition method in order to obtain a stable sheet resistance value even without the formation of copper silicide to tan silicide even in the subsequent heat treatment at high temperature The stacking prevention film for semiconductor device wiring materials and the capacitor of DRAM and FRAM devices in which a rapid increase in the sheet resistance of the diffusion barrier film following a subsequent heat treatment performed after the deposition of the thin film by stacking a thin film of any one type) Provided are a diffusion barrier and a method of manufacturing the same.

Description

A diffusion barrier film for semiconductor device wiring materials, a diffusion barrier film for DRAM / FRAM device capacitors, and a method of manufacturing the diffusion barrier film.

As a final step of the semiconductor integrated circuit manufacturing process, a wiring process or a metallization process is required to electrically connect the devices formed by the planar process. As the degree of integration of devices increases, the wiring process in the integrated circuit manufacturing process is high. It is becoming a key for yield and reliable device fabrication. In recent years, the wiring of the low resistance is connected in parallel to the upper layer of the semiconductor element, and the multilayer of the wiring which further lowers the resistance is performed. As a multi-layer or single-layer wiring material, aluminum or aluminum-based materials are widely used, but aluminum has a low melting point and low strength, which causes problems in reliability for long-term device operation. Cu, which is widely studied as the next-generation semiconductor wiring material, has lower electrical resistance and higher resistance to cell mobility than Al, but moves very quickly in Si and most metals. That is, it diffuses into Si through the metal layer, resulting in a short circuit of the device. In order to prevent the rapid diffusion of Cu, the diffusion barrier film should be free of chemical affinity with Cu, free from defects such as grain boundaries up to high temperatures, and have high solid solubility and resistance to high diffusion of Cu and Si.

So far, those studied as diffusion barriers between Cu and Si can be classified into six groups as follows.

1.Polycrystalline transition metal prevention film (W, Ti, Cr, Pd, Nb, V, etc.)

2. Polycrystalline or amorphous transition metal alloy prevention film (TiW, FeW, NiNb, IrTa, IrZr, etc.)

3. Polycrystalline or amorphous transition metal-Si barrier (TiSi ₂ , CoSi ₂ , CrSi ₂ , MoSi ₂ , WSi, TaSi ₂ , etc.)

4. Polycrystalline or amorphous transition metals -N, -O and -B protection films (TiN, WN, HfN, TaN, Ta ₂ N, RuO ₂ , TiB2, etc.)

5. Amorphous tertiary barrier (TiSiN, TaSiN, MoSiN, WSiN, TiPN, WBN, etc.)

6. Amorphous-C

Among them, much research has been conducted on Ta as an elemental barrier, and TiN and TiW, which has been successfully used as a diffusion barrier between Al and Si, have been studied as a compound barrier.

TiW can prevent diffusion to Cu to a relatively high temperature, but at a certain temperature, breakage of the diffusion barrier occurs due to decomposition reaction with Si.

TiN can act as a diffusion barrier in a relatively wide temperature range, but Cu diffuses along grain boundaries or defects generated at high temperatures, resulting in breakage of the barrier. However, since the TiN barrier film changes in electrical resistance, density, grain structure, and defect distribution of the TiN thin film according to deposition methods and conditions, the temperature at which the diffusion barrier film is stable for Cu is changed. Recently, research has been conducted to improve the characteristics of the barrier layer by blocking the grain boundaries by adding nitrogen, oxygen, and hydrogen through heat treatment during deposition or after deposition on the TiN diffusion barrier layer. However, unlike Al, a good result has not been obtained.

The polycrystalline diffusion barrier Ta has no chemical affinity and solid solubility with respect to Cu, but at a certain temperature, Cu diffuses along the grain boundaries and the diffusion barrier breaks. In order to prevent the grain boundary diffusion of Cu, there is no grain boundary which is a rapid diffusion path of Cu by adding Si to Ta, and an amorphous TaSi diffusion barrier film having a relatively high crystallization temperature has been developed. When the amorphous TaSi protective film is in contact with Cu, the crystal temperature, which determines the characteristics of the amorphous diffusion barrier film, is significantly reduced, and the protective film is damaged by reacting with Cu at a relatively low temperature. In order to improve the function of the non-crystalline TiSi film, research on amorphous tertiary compound film that increases the crystallization temperature and adds no grain boundary by adding N ₂ , which is not reactive with Cu and has no solid solubility, is performed in the TaSi compound. It is becoming. However, it has not been producing satisfactory results yet.

On the other hand, in the capacitor manufacturing process of DRAM / FRAM, heat treatment is performed at a relatively high temperature, a long time, and an oxidative atmosphere, and thus, the behavior of various chemical species in the ferroelectric material is changed due to the interfacial reaction between the electrode and the ferroelectric thin film. Depending on the interfacial microstructure of the liver, the physical and electrical properties of the ferroelectric are nourished. In addition, oxygen atoms contained in the dielectric thin film diffuse toward the polysilicon to form an oxide, which increases the electrical resistance in the electrode layer.

When platinum (Pt) is used as an electrode, platinum, which is an electrode material, is diffused into silicon substrates, silicides, and polycrystalline silicon to form platinum-silicides, which degrades the reliability of the device, and forms a dielectric thin film on the lower electrode in a high temperature oxygen plasma atmosphere. In this case, oxygen moves through the electrode layer and seriously affects not only the capacitor but also the transistor.

Therefore, there is an urgent need for research into oxygen in dielectric materials that impair the characteristics of capacitors and transistors, platinum as an electrode material, and diffusion barrier films for preventing diffusion of silicon onto electrode surfaces from silicon substrates, salicides and polycrystalline silicides.

Currently, oxygen or nitrogen filled polycrystalline nitride films (TiN, TaN, WN _1-X, etc.) as diffusion barriers of DRAM / FRAM capacitor electrodes are completely free of silicon and oxygen because oxygen and nitrogen easily move at low temperatures. Since it does not block and diffuses along the grain boundary, and the silicon oxide and platinum as electrode materials diffuse to form platinum-silicide, the filled polycrystalline-nitride diffusion barrier does not completely block the diffusion of oxygen, platinum and silicon.

Amorphous-Ta-Si-N, W-Si-N, etc., which has the most excellent characteristics among the diffusion barrier films developed to prevent the diffusion of Cu, which is attracting attention as the next-generation white paper material, are expanded with oxygen and silicon. It is applied as a diffusion barrier of the capacitor electrode to prevent the death, but because it is amorphous, the diffusion is slow, showing better properties than the polycrystalline-nitride diffusion barrier is filled, but does not completely block the diffusion of oxygen, silicon. In addition, since the crystallization occurs at a high temperature and a long heat treatment because it is amorphous, there is a disadvantage that the protective film properties appearing in the polycrystalline diffusion barrier film as it is. Therefore, the amorphous ternary diffusion barrier is superior to the filled polycrystalline-nitride diffusion barrier, but is fundamentally limited as a diffusion barrier for capacitors.

Ta is a material that does not solidify even Cu and 750 ℃ and does not form a compound, and many studies have been conducted as a material having good thermal stability between Cu and Si among pure metals. The present inventors deposited the Ta, which is most actively studied as a single diffusion barrier, by using an electron beam evaporation method and an ion beam assisted deposition method. The breakdown of the Ta diffusion barrier layer in the Cu / Ta / Si structure is known to cause the Cu diffusion to the Si substrate along the grain boundaries present in Ta, resulting in the breakdown of the diffusion barrier layer at 600 ° C or higher.

FIG. 1 shows the sheet resistance measurement results of subsequent heat treatment after depositing a Cu / Ta (300Å) / Si structure by electron beam evaporation. From the results of the sheet resistance measurement, the sheet resistance did not increase at 550 ℃ but the sheet resistance increased rapidly at the temperature of 600 ℃. Figure 1 also shows the results of the sheet resistance measurement of the specimen incorporating ion beam assisted deposition Ta as a diffusion barrier. The sheet resistance at 600 ℃ is not different from that of the unheated specimen, but the sheet resistance can be increased rapidly after 650 ℃ heat treatment. Therefore, it can be seen that the sheet resistance of the ion beam assisted deposition specimens is more thermally stable than the specimens deposited by the electron beam evaporation method.

Figure 2a shows the XRD analysis results according to the temperature of the specimen deposited by the electron beam evaporation method, Figure 2b shows the XRD analysis of the ion beam secondary deposition specimens.

When deposited by electron beam evaporation, Ta and Cu peaks were observed and no compound phase appeared until after 550 ° C heat treatment. However, in the XRD analysis after heat treatment at 600 ° C for 30 minutes, the Ta and Cu peaks at 550 ° C disappeared and TaSi ₂ , Cu The compound phase of ₃ Si appears, indicating that the Ta diffusion barrier film was completely destroyed after 600 ° C. heat treatment. This is in good agreement with the results of the sheet resistance measurement.

When deposited by the ion beam assisted deposition method, Ta and Cu peaks are visible even after 600 ° C. heat treatment, which is the breakdown temperature of the Cu / Ta / Si diffusion barrier film deposited by the electron beam evaporation method, and no silicon compound peaks are observed. However, in the XRD analysis after 650 ° C. heat treatment, the Cu peak and Ta peak disappeared, and the compound phases of TaSi ₂ , Cu ₄ Si, Cu ₃ Si appeared, and the Ta diffusion barrier was destroyed.

The present invention provides a diffusion barrier film which does not have a noticeable change in sheet resistance by using Ta, which is known as a single diffusion barrier material, as the diffusion barrier film material, without the formation of the above-described copper silicide or tantalum silicide even in the subsequent heat treatment at a temperature of 650 ° C or higher. The purpose.

FIG. 1 shows the sheet resistance measurement results of subsequent heat treatment after depositing a Cu / Ta (300Å) / Si structure by electron beam evaporation.

Figure 2a shows the XRD analysis results according to the temperature of the specimen deposited by the electron beam evaporation method, Figure 2b shows the XRD analysis of the ion beam secondary deposition specimens.

FIG. 3 shows the sheet resistance results of specimens in which Cu (100 μs) / Ta (125 μs) / W (50 μs) / Ta (125 μs) / Si structures were deposited by ion beam assisted deposition.

4 shows the results of XRD analysis on specimens of the structure of Cu / Ta / W / Ta / Si deposited by ion beam assisted deposition.

5 shows the results of heat treatment sheet resistance of a specimen having a Cu / Ta / W / Ta / Si structure deposited by ion beam assisted deposition according to the present invention.

Figure 6 shows the XRD analysis results according to the temperature of the specimen deposited by the Cu-Ta / W / Ta / Si structure by ion beam assisted deposition.

7 shows the sheet resistance measurement results after heat treatment of a specimen having a Cu / Ta / Nb / Ta / Si structure deposited by ion beam assisted deposition according to the present invention.

FIG. 8 shows the XRD analysis results according to the temperature of specimens in which Cu / Ta / Zr / Ta / Si structures were deposited by ion beam assisted deposition.

9 shows the sheet resistance measurement results after heat treatment of a specimen having a Cu / Ta / Nb / Ta / Si structure deposited by ion beam assisted deposition according to the present invention.

The present invention has a diffusion barrier thin film configuration of Ta / M / Ta (wherein M is any one of W, Zr, Nb, and V), whereby the sheet resistance of the diffusion barrier is subjected to subsequent heat treatment after deposition of the thin film. Provided are a diffusion barrier film for semiconductor element wiring material and a method for producing the diffusion barrier film by an ion beam assisted deposition method in which rapid increase occurs at 650 ° C or higher.

In addition, the present invention has a diffusion barrier thin film configuration of Ta / M / Ta (M is any one of W, Zr, Nb and V), so that the diffusion barrier of the diffusion prevention film according to the subsequent heat treatment after the deposition of the thin film Provided are a diffusion barrier film for capacitors of DRAM and FRAM devices in which sheet resistance is rapidly increased at 650 占 폚 or higher, and a method of manufacturing the diffusion barrier film by ion beam assisted deposition.

Description of the Preferred Embodiments

The diffusion barrier fracture mechanism of Cu, a wiring material developed so far, is caused by the formation of copper silicide (η˝-Cu ₃ Si) at the diffusion barrier layer / Si interface through the microstructure defect of the barrier layer during heat treatment. It is reported. In addition, in the DRAM / FRAM capacitor, the diffusion barrier is formed by dispersing oxygen, electrode material, silicon, etc. through defects such as grain boundaries of the electrode material and diffusion barrier during deposition or post-heat treatment to form corals and silicides, thereby preventing the barrier from breaking. I'm reporting. Therefore, since the microstructure of the diffusion barrier itself affects the diffusion barrier properties, the control of the microstructure is very important for improving the diffusion barrier performance. In order to improve the diffusion barrier properties, various single metal and compound barrier films have been studied, and these microstructures are reported to be changed according to deposition methods and conditions.

The ion beam co-deposition method simultaneously irradiates an ion beam from a separate ion source when depositing a thin film, so that the deposited film has density, resistance to oxidation, stress state, and average grain size. ), It has been reported to induce changes in physical properties such as electrical and mechanical quality by inducing changes in crystal grains having preferred oriention, improvement in adhesion between the thin film and the substrate, and the like. These changes in the thin film to be formed are ion pinning caused by momentum transfer from the ion guns irradiated simultaneously from the ion gun irradiated at the nucleation in the initial stage of deposition and the growth of the thin film. As a result, thin film morphoiogy results from decomposition of small clusters by ion peening effect, ion bombardment enhanved adatom diffusion, and resputtering effect. The microstructure, defect concentraton, preferred orientation, stress state and physical properties change.

The inventors have observed that the specimens of Cu / Ta / Si structure deposited by electron beam evaporation method from the above-described sheet resistance measurement results and XRD analysis results maintain the structure of Cu / Ta / Si without increasing the sheet resistance and reaction products up to 550 ° C. It was found that the pre-deposited specimen was stable up to 600 ° C., which was 50 ° C. higher.

The inventors of the above-described studies of Cu / Ta (300 Pa) / Si structure revealed that the Ta diffusion barrier film deposited by the ion beam assisted deposition method was superior to the Ta diffusion barrier film deposited by the electromagnet evaporation method. However, the Ta diffusion barrier film deposited by ion beam assisted deposition method has no change in thermal stability up to 600 ° C, so that the Ta / Si interface is very stable, but at 650 ° C, Cu diffuses along the dense Ta grain boundary and at the same time, It was found out that Ta diffused out to destroy the diffusion barrier.

The present inventors have found the following facts after continuous research for improving the performance of the diffusion barrier.

That is, since the ion diffusion assisted Ta diffusion barrier has a grain boundary and Cu diffuses along the grain boundary, introducing a new interface to block the grain boundary between the Ta layers effectively prevents the diffusion of Cu and Si. Therefore, the performance of the diffusion barrier can be improved. In the present invention, M (W, Zr, Nb, V), which can play such a role, is introduced between Ta as a blocking layer. That is, W, Zr, Nb, and V are elements that react with Si at 600 ° C. or higher and do not react with Ta even at a temperature of 800 ° C., and thus, W, Zr, Nb, and V are introduced into the intercalation layer of the Ta layer of the diffusion barrier film in the present invention.

Example

In order to change the microstructure of the diffusion barrier film, a diffusion barrier film was deposited by ion beam assisted deposition. At this time, the ion beam energy and the ion current density were controlled by the deposition parameters. The ion beam energy is preferably 100 to 250 eV, more preferably 150 to 200 eV. The ion beam current density is preferably 0.1 to 0.15 mA, more preferably 0.1 to 0.13 mA. By adjusting the ion beam energy within the above range, the structure of Cu / Ta / M / Ta / Si (M = W, Zr, Nb, V) was deposited by evaporation with a vacuum beam on the Ta diffusion preventing film while changing the microstructure. Configured.

(Example 1)

For Cu / Ta / W / Ta / Si

FIG. 3 shows the results of measuring sheet resistance of specimens in which Cu (1000 Å) / Ta (125 Å) / W (50 Å) / Ta (125 Å) / Si structures were deposited by ion beam assisted deposition. Up to 600 ° C, the sheet resistance of the specimens unannealed was the same. At 650 ° C and 700 ° C, the sheet resistance decreased slightly. After the heat treatment at 750 ℃, the sheet resistance increased to 1.4 Ω / �. From the sheet resistance measurement results, it can be seen that after 750 ° C. heat treatment, Cu began to diffuse through the diffusion barrier.

That is, when comparing the Cu / Ta / Si structure deposited by the electron beam evaporation method or the ion beam assisted deposition method with the ion beam assisted deposition Cu / Ta / W / Ta / Si structure according to the present invention, Cu / Ta It can be seen that the sheet resistance increased at a temperature of 100 ° C. higher than the / Si structure.

4 shows the results of XRD analysis on specimens of the structure of Cu / Ta / W / Ta / Si deposited by ion beam assisted deposition. Although the Ta peak was hardly seen in the analysis results of the unannealed specimens, three Ta peaks were clearly visible after the 700 ° C. heat treatment, and the Cu (111) peak intensity was significantly increased. After the 750 ° C. heat treatment, the Ta peak disappeared and the Cu (111) peak intensity appeared to decrease slightly. From the above results, it can be seen that in the specimen according to the present invention, Si and Ta did not react up to 750 ° C.

(Example 2)

For Cu / Ta / Zr / Ta / Si

5 shows the sheet resistance measurement results after heat treatment of a specimen having a Cu / Ta / Zr / Ta / Si structure deposited by ion beam assisted deposition according to the present invention. There was no increase in sheet resistance up to 750 ℃, and the sheet resistance increased rapidly at 800 ℃ to 20Ω / �. In the case of ion-assisted deposition of Cu / Ta / Zr / Ta / Si, sheet resistance began to increase at 150 ℃ higher than Cu / Ta / Si and 50 ℃ higher than Cu / Ta / W / Ta / Si. Sheet resistance began to increase.

Figure 6 shows the XRD analysis results according to the temperature of the specimen deposited by Cu-Ta / Zr / Ta / Si structure by ion beam assisted deposition. It can be seen that in the specimen which was not heat-treated, there was no apparent peak other than the Cu (111) peak. One Ta peak was observed in the 750 ° C analysis, and the Cu (111) peak intensity was increased. After 800 ℃ heat treatment, Cu peak disappeared completely, and Ta, TaSi ₂ , Cu ₄ Si, Cu ₃ Si peaks were seen.

In the sheet resistance measurement results and XRD analysis results, the Cu / Ta / Zr / Ta / Si structured specimens were etched at 800 ° C., and the diffusion barrier was destroyed at 800 ° C., and Cu reacted with Si to form a Cu ₄ Si phase.

(Example 3)

For Cu / Ta / Nb / Ta / Si

7 shows the sheet resistance measurement results after heat treatment of a specimen having a Cu / Ta / Nb / Ta / Si structure deposited by ion beam assisted deposition according to the present invention. There was no increase in sheet resistance up to 750 ℃ and the sheet resistance increased rapidly at 800 ℃ to 7Ω / �. Ion Beam Assisted Cu / Ta / Nb / Ta

As with Cu / Ta / Zr / Ta / Si, the sheet resistance began to increase at 150 ℃ higher than that of Cu / Ta / Si and the sheet resistance at 50 ℃ higher than that of Cu / Ta / W / Ta / Si. This began to increase.

FIG. 8 shows the XRD analysis results according to the temperature of specimens in which Cu / Ta / Zr / Ta / Si structures were deposited by ion beam assisted deposition. It can be seen that in the specimen which was not heat-treated, there was no apparent peak other than the Cu (111) peak. One Ta peak was observed in the 750 ° C analysis, and the Cu (111) peak intensity was increased. After 800 ℃ heat treatment, Cu peak disappeared completely, and Ta, TaSi ₂ , Cu ₃ Si peaks were seen.

In the sheet resistance measurement results and XRD analysis results, it can be seen that in the specimens of Cu / Ta / Nb / Ta / Si structure with ion beam assisted deposition, the diffusion barrier was destroyed at 800 ° C., and Cu reacted with Si to form a Cu ₃ Si phase.

(Example 4)

Cu / Ta / V / Ta / Si

9 shows the sheet resistance measurement results after heat treatment of a specimen having a Cu / Ta / Nb / Ta / Si structure deposited by ion beam assisted deposition according to the present invention. There was no increase in sheet resistance up to 750 ℃ and the sheet resistance increased rapidly to 9 ℃ / � at 800 ℃. Cu / Ta / V / Ta / Si based on ion beam assisted deposition also had a sheet resistance at a temperature 150 ° C higher than Cu / Ta / Si based on Cu / Ta / Zr / Ta / Si and Cu / Ta / Nb / Ta / Si. It started to increase and the sheet resistance began to increase at a temperature of 50 ° C. higher than the Cu / Ta / W / Ta / Si system.

As described above, the interdiffusion at the Cu / Ta / M / Ta / Si (M is any one of W, Zr, Nb, or V) interface is caused by the diffusion of Cu and the flying M in the Cu / Ta / Si system. The increase in thermal stability when inserted is thought to be because the blocking layer formed by the Ta / M mixture by ion beam assisted deposition effectively prevented the diffusion of Cu.

According to the present invention, a diffusion barrier film for semiconductor device wiring materials and a capacitor diffusion barrier film for capacitors of DRAM and FRAM devices can be obtained in which stable sheet resistance values can be obtained without formation of copper silicide or tantalum silicide even at high temperature subsequent heat treatment of 650 ° C or higher. .

Claims (6)

Having a diffusion barrier thin film configuration of Ta / M / Ta (wherein M is any one of W, Zr, Nb, and V), a rapid increase in sheet resistance of the diffusion barrier is 650 due to subsequent heat treatment after deposition of the thin film. Diffusion prevention film for semiconductor element wiring materials characterized by above-mentioned degree C. The diffusion barrier for semiconductor device wiring material according to claim 1, wherein the total thickness of the diffusion barrier is 500 kPa or less. Having a diffusion barrier thin film configuration of Ta / M / Ta (wherein M is any one of W, Zr, Nb, and V), a rapid increase in sheet resistance of the diffusion barrier due to subsequent heat treatment performed after deposition of the thin film is 650. A diffusion barrier film for capacitors in DRAM and FRAM devices, characterized in that it is made at or above 캜. The diffusion barrier for capacitors of DRAM and FRAM devices according to claim 1, wherein the total thickness of the diffusion barrier is 500 kPa or less. In the ion beam assisted deposition method, a diffusion barrier thin film having a structure of Ta / M / Ta (wherein M is any one of W, Zr, Nb, and V) while controlling ion beam energy and ion beam energy to 100 to 250 eV and 0.1 to 0.15 GHz, respectively. A method for producing a diffusion barrier for semiconductor element wiring material, characterized in that the layer is laminated. In the ion beam assisted deposition method, a diffusion barrier thin film having a structure of Ta / M / Ta (wherein M is any one of W, Zr, Nb, and V) while controlling ion beam energy and ion beam energy to 100 to 250 eV and 0.1 to 0.15 GHz, respectively. A method of manufacturing a diffusion barrier for a DRAM and a FRAM element capacitor, characterized in that the lamination.