JP2005026704A - METHOD FOR MANUFACTURING SEMICONDUCTOR DEVICE, AND Ti-W MATERIAL FOR MAGNETRON SPUTTERING SYSTEM - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress leakage current of a semiconductor device, in which a film which consists of a high melting-point metal, alloy which consisting of the high melting-point metal, and silicide of the high melting-point metal, nitride of Ti, Ta, W, and Ti-W alloy, is used for a contact barrier layer or a gate electrode or the like, for obtaining a highly reliable semiconductor device. <P>SOLUTION: A method for manufacturing the semiconductor device includes the processes of removing Al from Ti-W material, preparing W material for a magnetron sputtering system whose concentration of Al is 1 ppm or lower, using the Ti-W material, and forming the contact barrier or the gate electrode layer, in which the Al content is suppressed to about 1×10<SP>18</SP>atoms/cm<SP>3</SP>or lower, expressed in terms of the number of the atoms, by a sputtering method. The bonding depth of a source-drain region is 0.3μm or shorter. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a semiconductor element, and a Ti-W material for a magnetron sputtering apparatus capable of forming a high-purity conductive film constituting a contact barrier layer or gate electrode for the semiconductor element.

  In the contact portion of the semiconductor element, as a contact barrier layer for preventing the precipitation of silicon into the aluminum wiring while preventing the Pn junction from being broken by the aluminum atoms diffusing from the aluminum wiring in the direction of the pn substrate. For example, a TiN film or the like is formed between the silicon substrate and the aluminum wiring. Such a material for the contact barrier layer is required to have low resistance and to have characteristics of heat resistance and chemical stability due to requirements in the LSI manufacturing process. In order to satisfy the above-described requirements for the material of the contact barrier layer, application of a refractory metal or an alloy made of a refractory metal, a metal silicide, a Ti, Ta, or Ti-W alloy nitride film is considered. And some have been implemented.

  In recent years, higher integration of semiconductor elements has progressed, and as a result, the element structure tends to be further miniaturized. According to the principle of scaling, it is known that the size of the device in the vertical direction is reduced at substantially the same rate in response to the reduction in the size of the IC in the horizontal direction. According to this, the junction depth of the source-drain region is expected to be 0.1 to 0.15 μm in, for example, a 16M DRAM having a design rule of 0.5 μm. As the junction depth of the source-drain region decreases, the leakage current of the device tends to increase. This is because the influence of impurities contained in the material of the contact barrier layer on the source-drain region becomes relatively large as the junction depth of the source-drain region becomes small, and induces a leakage current. is there. In general, the leakage current of a semiconductor element causes a malfunction and decreases the reliability of the semiconductor element, so it is desired to have a lower value. The increase in leakage current that occurs is considered to be an obstacle to high integration of semiconductor elements in the future.

  As impurities contained in the contact barrier, it is considered that the following impurities may adversely affect the semiconductor element, and the reduction thereof is attempted.

(1) Alkali metals such as Na and K (generation of interface states)
Na, K are easily element is diffused in SiO _2, moves to the interface between the Si and the gate insulating film during the manufacturing process of the device (SiO _2), and in part become positively charged ionized, surfactant Generate a level. The charge at such an interface becomes a problem by trapping charges in Si such as carriers flowing in the channel.

(2) Radioactive elements such as U and Th (soft error)
For U, Th, etc., a trace amount of radioactive material decays, and an α-ray emitted at that time induces an electron-hole pair in Si, causing a temporary malfunction due to the charge.

(3) Heavy metals such as Fe and Cr (decreasing interface properties)
Since heavy metals such as Fe and Cr have higher concentrations in the film than alkali metals such as Na and K, they gather at the Si-SiO ₂ interface even when the mobility increases as Na and K, and interface states. And a threshold voltage.

The semiconductor element material contains about 1 × 10 ¹⁹ atoms / cm ^{3 of} these impurities per unit volume, although it varies depending on the manufacturing process. Some of these impurities are thought to have the effect of increasing the leakage current in addition to the effects such as the generation of interface states and deterioration of interface characteristics, which have already been reduced as much as possible. However, with the high integration of semiconductor elements in the future, further reduction of leakage current is required.

On the other hand, as a gate electrode material for forming a gate portion of a semiconductor element, low resistance and heat resistance are required. Therefore, application of a refractory metal is considered in the same manner as a contact barrier material. Also, as the integration of elements increases, the junction depth of the source-drain region decreases, the distance between the gate electrode and the pn junction interface becomes shorter, and the SiO ₂ film thickness also becomes smaller. As in the case of the contact barrier material, the impurity in the electrode material affects the source-drain region and induces a leakage current from the portion where the drain region is close to each other through SiO ₂ , thereby increasing the leakage current of the semiconductor element. The possibility of is increased.
JP 60-66425 A

  As described above, the increase in leakage current cannot be ignored due to the high integration of semiconductor elements. In order to obtain a highly reliable semiconductor device, a high melting point metal, a high melting point metal alloy, a high melting point metal silicide, a film made of a Ti, Ta, W, or Ti-W alloy nitride is used as a contact barrier layer or gate. It is used for an electrode or the like and aims to suppress a leakage current of a semiconductor element.

In order to achieve the above object, a method for manufacturing a semiconductor device according to the present invention includes, as described in claim 1, W for a magnetron sputtering apparatus in which Al is removed from a Ti—W raw material and an Al concentration is 1 ppm or less. A source characterized in that a material is prepared and a contact barrier or gate electrode layer having an Al content of 1 × 10 ¹⁸ atoms / cm ³ or less is formed by sputtering using this Ti—W material. This is a method for manufacturing a semiconductor element in which the junction depth of the drain region is 0.3 μm or less.

  In the method for manufacturing a semiconductor device, it is preferable that the junction depth of the source-drain region is 0.15 μm or less.

  Furthermore, in the method for manufacturing a semiconductor element, as described in claim 3, it is preferable that the junction depth of the source-drain region is 0.1 μm or less.

In the method for manufacturing a semiconductor device, as described in claim 4, the Al content of the contact barrier or the gate electrode layer is preferably 1 × 10 ¹⁷ atoms / cm ³ or less in terms of the number of atoms.

The Ti-W material for a magnetron sputtering apparatus according to the present invention includes, as described in claim 5, Al content in a contact barrier or gate electrode layer of a semiconductor element having a junction depth of a source-drain region of 0.3 μm or less. The Ti—W material for a magnetron sputtering apparatus, which can be formed in an amount of 1 × 10 ¹⁸ atoms / cm ³ or less in terms of the number of atoms and has an Al concentration of 1 ppm or less.

  Moreover, in the Ti-W material for the magnetron sputtering apparatus, as described in claim 6, it is preferable that the junction depth of the source-drain region is 0.15 μm or less.

  Furthermore, in the Ti-W material for the magnetron sputtering apparatus, as described in claim 7, it is preferable that the junction depth of the source-drain region is 0.1 μm or less.

In the Ti-W material for a magnetron sputtering apparatus, as described in claim 8, the Al content of the contact barrier or the gate electrode layer is 1 × 10 ¹⁷ atoms / cm ³ or less in terms of the number of atoms. preferable.

  Furthermore, in the Ti—W material for the magnetron sputtering apparatus, it is preferable that the contact barrier or the gate electrode layer is made of W nitride as described in claim 9.

In order to achieve the above object, the sputtering target used in the present invention is characterized in that a high-purity conductive film having an Al content of 1 × 10 ¹⁸ atoms / cm ³ or less can be formed. To do.

In addition, the sputtering target used in the present invention is a high-purity conductive film having an Al content of 1 × 10 ¹⁸ atoms / cm ³ or less in terms of the number of atoms (however, a conductive film made of a Mo—W alloy or nitride is used. Except for the above)).

  The high-purity conductive film is made of at least one metal selected from Ti, W, Mo, Zr, Hf, Ta, V, Nb, Ir, Fe, Ni, Cr, Co, Pd, and Pt. Good.

  Further, the high-purity conductive film is a silicide of at least one metal selected from Ti, W, Mo, Zr, Hf, Ta, V, Nb, Ir, Fe, Ni, Cr, Co, Pd and Pt. Consists of.

  Moreover, you may comprise so that the high purity electroconductive film | membrane consisting of a silicide may be obtained by making it react after forming into a film by the sputtering method using a sputtering target.

  The high-purity conductive film is preferably used for a contact barrier layer or gate electrode of a semiconductor element.

  Furthermore, various semiconductor elements are formed using the high-purity conductive film.

The high-purity conductive film is made of a conductor (excluding a conductor made of Mo-W alloy or nitride), and the Al content in the conductor is 1 × 10 ¹⁸ atoms / number. A high-purity conductive film having a size of cm ³ or less is formed by a sputtering method using a sputtering target. Furthermore, the conductor may be made of at least one metal selected from Ti, W, Mo, Zr, Hf, Ta, V, Nb, Ir, Fe, Ni, Cr, Co, Pd, and Pt.

The high-purity conductive film is a silicide of at least one metal selected from Ti, W, Mo, Zr, Hf, Ta, V, Nb, Ir, Fe, Ni, Cr, Co, Pd, and Pt. A high-purity conductive film having an Al content of 1 × 10 ¹⁸ atoms / cm ³ or less in terms of the number of atoms is formed by a sputtering method using a sputtering target. Further, the film may be obtained by reacting after film formation by sputtering.

  The leakage current of the semiconductor element is induced by the impurities contained in the material of the contact barrier layer or the gate electrode affecting the source-drain region. The present invention has been made by finding that the concentration of Al, which has not been considered important as an impurity in the material of the contact barrier layer or the gate electrode, is greatly related to the leakage current.

In the present invention, the Al content is set to 1 × 10 ¹⁸ atoms / cm ³ or less in terms of the number of atoms, the leakage current increases as the Al content increases to an extent exceeding 1 × 10 ¹⁸ atoms / cm ^3. As the junction depth of the source-drain region increases, it becomes susceptible to the influence of Al contained in the contact barrier layer, and the leakage current increases, but if it is set to 1 × 10 ¹⁸ / cm ³ or less, the source-drain This is because the leakage current can be suppressed to a substantially constant low value regardless of the junction depth of the region.

  In the present invention, Ti, W, Mo, Zr, Hf, Ta, V, Nb, Ir, Fe, Ni, Cr, Co, Pd, and Pt used as materials constituting the conductive film formed by the sputtering target are used. Metals and silicides and nitrides of these metals all have excellent conductivity and low resistance characteristics, and are used alone or in combination of two or more.

Among the above conductive films, TiN, Mo, W, TiSi ₂ , CoSi _{2 and the} like are particularly excellent in thermal stability and chemical stability, and have the effect of reducing contact resistance when used as a contact barrier. Practically preferred.

However, Al contained in the thin film segregates at the interface between the contact barrier layer and the source or drain in the subsequent process, reacts with oxygen remaining at the interface, or reduces the native oxide film of Si to reduce Al _2. There is a high possibility of forming O ₃ . As a result, the contact resistance increases and becomes a problem. Therefore, the present inventors investigated the relationship between the Al concentration in the thin film and the contact resistance when a contact barrier layer was formed with these thin films. As a result, when the Al concentration is 1 × 10 ¹⁸ pieces / cm ³ or less, it is clear that the problem of the increase in contact resistance due to the formation of Al ₂ O ₃ as described above can be avoided and no problem is caused in practice. became.

  In the present invention, the effect of reducing the leakage current of the semiconductor element can be obtained whether the crystalline state of the conductive film formed with the sputtering target is crystalline or amorphous (amorphous). In general, amorphous is slightly inferior in thermal stability, but metals such as Ta—Ir, Ni—Nb, and Fe—W are relatively stable, and thus are practically used as amorphous. Since such an amorphous alloy has no grain boundary, Al hardly diffuses at high speed, and a better effect can be obtained.

In the present invention, the conductive film formed by the sputtering target is manufactured, for example, in the following manner. That is, when forming a high-melting point metal or high-melting point alloy film, a high-melting point metal silicide film, a high-purity contact barrier film made of a nitride film of Ti, Ta, W, or Ti—W alloy, or a gate electrode film, The sputtering method generally used for film formation of the element is used, and at that time, the Al content in the generated film is suppressed by forming a film using a sputtering target in which the Al concentration is reduced to a predetermined value or less. There is a correlation between the concentration of Al in the sputtering target and that in the film. For example, to suppress the content of Al atoms in the Ti—W alloy and Mo silicide films to 1 × 10 ¹⁸ atoms / cm ³ or less, The Al concentration in the Ti—W alloy sputtering target or Mo silicide sputtering target is suppressed to 30 ppm or less, preferably 10 ppm or less, more preferably 1 ppm or less in terms of atomic ratio, and sputtering is performed using this target to form a film.

In the case of forming a conductive film with a refractory metal, an alloy composed of a refractory metal, and a metal silicide, a target having an Al concentration of 30 ppm or less, preferably 10 ppm or less, more preferably 1 ppm or less is used. By performing sputtering, the Al content in the film can be suppressed to 1 × 10 ¹⁸ pieces / cm ³ or less. Further, when the conductive film is formed of a nitride of Ti, Ta, W, Ti—W alloy, the Al concentration in the target made of Ti, Ta, W, Ti—W alloy is 30 ppm or less, preferably 10 ppm or less, More preferably, it is 1 ppm or less, and by performing active sputtering in a nitrogen gas atmosphere, the Al content in the film can be suppressed to the above value (1 × 10 ¹⁸ / cm ³ ) or less. Further, it is necessary to sufficiently reduce the concentrations of heavy metal elements and alkali metals which have been conventionally gathered at the interface of the laminated film to deteriorate the interface characteristics and cause junction leakage.

  Hereinafter, the present invention will be described in detail by way of examples.

  In the present invention, by using a high-purity conductive film for a semiconductor element formed using a sputtering target and forming a contact barrier, a gate electrode, or the like, there is an effect of suppressing a leakage current, and a highly reliable semiconductor element is obtained. As a result, it can sufficiently cope with future high integration of semiconductor elements.

Example 1
As shown in FIG. 15, a contact barrier layer 1 as a conductive film made of Ti-W is formed on a p + region 2 formed on an n-type substrate 3, and an Al layer 4 as a wiring film is further formed thereon. The formed diode was produced as a semiconductor element. The junction depth of the source-drain region of this diode is about 0.3 μm, and the area of the opening is 1.5 × 1.5 μm ² . This diode models a contact portion of a semiconductor element, and the area of the contact portion, the thickness of the contact barrier layer, and the junction depth of the source-drain region simulate an actual device.

  Here, the contact barrier layer was formed as follows.

A high purity Ar powder having a maximum particle size of 10 μm or less (average particle size of 4 μm) and a high purity Ti powder having a maximum particle size of 50 μm or less (average particle size of 30 μm) are mixed so as to be 10 wt% Ti-W. The mixture was mixed for 48 hours in a ball mill replaced with gas. Next, a BN mold release agent was applied to a graphite mold, a Ta plate was attached to the surface, and the mixed powder was filled into the mold. This molding die was inserted into a hot press apparatus, and was densified and sintered at a pressure of 250 kg / cm ² at 1400 ° C. for 3 hours in a vacuum of 5 × 10 ⁻⁴ Torr or less (first manufacturing method) ). The obtained sintered body was finished into a target having a diameter of 260 mm and a thickness of 6 mm by machining. When the concentration of Al in the target was analyzed, it was 0.8 ppm.

  A similar target was produced by the same production method as the first production method except that no Ta plate was used during hot pressing, and the Al concentration in this target was analyzed and found to be 15 ppm.

  Further, a W plate having a purity of 99.9 wt% and a maximum particle size of 50 μm or less (average particle size of 30 μm) and a Ti powder having a purity of 99.9 wt% and a maximum particle size of 100 μm (average particle size of 70 μm) are used during hot pressing. A similar target was produced by the same production method as in the first production method except that was not used, and the Al concentration in the target was analyzed and found to be 50 ppm.

Using these targets, a contact barrier layer made of Ti—W was formed by sputtering. When measured by flameless atomic absorption, the Al content in each Ti-W film was 1 × 10 ¹⁷ pieces / cm ³ , 1 × 10 ¹⁸ pieces / cm ³ , and 1 × 10 ¹⁹ pieces / cm ^{3, respectively.} It was. Each film thickness is about 80 nm.

Next, the relationship between the Al content in the Ti—W contact barrier layer and the pn junction leakage current was examined. First, a reverse bias voltage was applied to each diode from OV, the voltage was gradually increased, and the leakage current of each diode until breakdown was examined. The result is shown in FIG. The horizontal axis in FIG. 1 represents the reverse bias voltage, and the vertical axis represents the leakage current. In FIG. 1, the curve A has an Al content of 1 × 10 ¹⁹ pieces / cm ³ , the curve B has an Al content of 1 × 10 ¹⁸ pieces / cm ³ , and the curve C has an Al content of 1 × 10 ¹⁷ pieces / cm 3. ³ shows current-voltage characteristics of a diode using the film No. ³ . The content of impurities other than Al is sufficient for all samples in which heavy metals other than Al, Ti and W are 5 × 10 ¹⁶ atoms / cm ³ or less in terms of the number of atoms and alkali metals are 5 × 10 ¹⁶ atoms / cm ³ or less. It is a low value.

  As is apparent from the results of FIG. 1, when the Al content is controlled to be equal to or lower than the predetermined value, the leakage current value hardly changes between B and C, but greatly increases in the sample of A. Since the concentration of other harmful impurities is sufficiently low, the increase in leakage current is considered to be due to the increase in Al content. Therefore, an increase in leakage current can be effectively suppressed by reducing the Al content in the film.

Example 2
The relationship between the Al content in the Ta-Ir amorphous contact barrier layer and the pn junction leakage current was examined using a diode having a contact barrier layer made of Ta-Ir and others having the same configuration as in Example 1. The Ta—Ir amorphous contact barrier layer was formed using a 48.5 wt% Ta—Ir composite target having Al concentrations of 100 ppm and 30 ppm, respectively. When each barrier layer was measured by flameless atomic absorption, the Al content in each film was 8 × 10 ¹⁸ pieces / cm ³ and 4 × 10 ¹⁷ pieces / cm ³ . The film thickness is about 90 nm. Each measurement was performed in the same manner as in Example 1. The measurement result of the pn junction leakage current value with respect to the reverse bias voltage is shown in FIG.

In FIG. 2, curve A shows the current-voltage characteristics of a diode in which an Al content is 8 × 10 ¹⁸ pieces / cm ³ , and curve B shows a diode having an Al content of 4 × 10 ¹⁷ pieces / cm ^3. Yes. In any film, the contents of heavy metal elements other than Ta are sufficiently low values of 1 × 10 ¹⁷ pieces / cm ³ or less and alkali metal of 0.5 × 10 ¹⁶ pieces / cm ³ or less. As is apparent from the curve B in FIG. 2, an increase in leakage current can be effectively suppressed by setting the Al content in the film to a predetermined value or less.

Example 3
A contact barrier layer made of Ni—Nb amorphous is used, and the rest of the Al content in the Ni—Nb amorphous contact barrier layer and the pn junction leakage current are measured using a diode having the same configuration as in Example 1 and the measurement method. Relevance was examined. The Ni—Nb amorphous contact barrier layer was formed using a 61 wt% Ni—Nb composite target having Al concentrations of 180 ppm and 10 ppm, respectively. When each barrier layer was measured by flameless atomic absorption, the Al content in each Ni—Nb amorphous contact barrier film was 1.5 × 10 ¹⁹ / cm ³ and 1 × 10 ¹⁷ / cm ³ . there were. The film thickness is about 90 nm. Each measurement was performed in the same manner as in Example 1. The measurement result of the pn junction leakage current value with respect to the reverse bias voltage is shown in FIG.

In FIG. 3, curve A shows the current-voltage characteristics of a diode using a film having an Al content of 1.5 × 10 ¹⁹ pieces / cm ³ , and curve B shows a Al content of 1 × 10 ¹⁷ pieces / cm ^3. Yes. In any of the films, the content of heavy metal elements other than Ni and Nb is 1 × 10 ¹⁷ pieces / cm ³ or less and the alkali metal is 3 × 10 ¹⁶ pieces / cm ³ or less, which are sufficiently low values. As apparent from curve B in FIG. 3, an increase in leakage current can be effectively suppressed by reducing the Al content in the film below a predetermined value.

Example 4
Using a diode having the same structure as that of Example 1 and the measuring method, the Al content in the Fe-W amorphous contact barrier layer and the pn junction leakage current The relevance of was investigated. The formation of the Fe—W amorphous contact barrier layer was performed using a 23.3 wt% Fe—W composite target having Al concentrations of 150 ppm and 15 ppm, respectively. When each barrier layer was measured by flameless atomic absorption, the Al content in each Fe—W amorphous contact barrier film was 2.6 × 10 ¹⁸ pieces / cm ³ and 1 × 10 ¹⁷ pieces / cm ³ . there were. The film thickness is about 90 nm. Each measurement was performed in the same manner as in Example 1. The measurement result of the pn junction leakage current value with respect to the reverse bias voltage is shown in FIG.

In FIG. 4, curve A shows the current-voltage characteristics of a diode using a film with an Al content of 2.6 × 10 ¹⁸ pieces / cm ³ and curve B with an Al content of 1 × 10 ¹⁷ pieces / cm ^3. ing. In any film, the content of heavy metal elements other than Fe and W is 1 × 10 ¹⁷ pieces / cm ³ or less, and the alkali metal is 0.5 × 10 ¹⁶ pieces / cm ³ or less. As apparent from curve B in FIG. 4, an increase in leakage current can be effectively suppressed by reducing the Al content in the film to a predetermined value or less.

Example 5
The relationship between the Al content in the Ti silicide contact barrier layer and the pn junction leakage current was examined using a diode having a contact barrier layer made of Ti silicide and the other structure having the same structure as in Example 1. Here, the Ti silicide contact barrier layer was formed by sputtering using a 56.0 wt% Ti—Si composite target having an Al concentration of 150 ppm and 10 ppm in Ti, respectively.

  Here, the Ti-Si composite target having an Al concentration of 150 ppm is obtained by arc-melting sponge Ti produced by the crawl method to form a Ti ingot having a diameter of 140 mm, this ingot is forged hot, and further shaped into a predetermined shape by mechanical grinding. A base material was processed to form a target, and Si blocks having a purity of 5N were arranged in a mosaic pattern on the surface of the Ti target so that Ti was 56% in area ratio.

On the other hand, a target having an Al concentration of 10 ppm was charged with an electrode made of sponge Ti in a KCl-NaCl electrolytic bath (KCl: 16% by weight, NaCl: 84% by weight), with an electrolysis temperature of 755 ° C., a current of 200 A, and a voltage of 8V. Molten salt electrolysis was performed to produce granular acicular Ti. Next, in order to remove Al remaining on the surface of the needle-like Ti, it is further washed with an NaOH solution, washed with water, and then subjected to electron beam melting (EB melting) under the conditions of 5 × 10 ⁻⁵ mbar and output 30 KW. A Ti ingot having a diameter of 135 mm was used. This Ti ingot was cold forged to make a base material, and the target was made in the same process as the target having an Al concentration of 150 ppm. In addition, when the Al concentration in the Si block used as the silicon component of both targets was measured, both levels were 1 ppm or less.

When films formed by sputtering using these targets were measured by flameless atomic absorption, the Al content in each film was 5 × 10 ¹⁸ pieces / cm ³ and 1 × 10 ¹⁷ pieces / cm ³ . there were. The film thickness is about 90 nm. Each measurement was performed in the same manner as in Example 1. The measurement result of the pn junction leakage current value with respect to the reverse bias voltage is shown in FIG.

In FIG. 5, curve A shows the current-voltage characteristics of a diode using a film having an Al content of 5 × 10 ¹⁸ pieces / cm ³ and curve B using an Al content of 1 × 10 ¹⁷ pieces / cm ³ . . In any of the films, the content of heavy metal elements other than Ti is sufficiently low, 2 × 10 ¹⁷ pieces / cm ³ or less and alkali metal is 1 × 10 ¹⁶ pieces / cm ³ or less. As is clear from curve B in FIG. 5, an increase in leakage current can be effectively suppressed by reducing the Al content in the film to a predetermined value or less.

Example 6
A high-purity W powder having a maximum particle size of 10 μm or less and a high-purity Si powder having a maximum particle size of 30 μm or less were mixed so as to be 70.8 wt% W-Si, and mixed for 48 hours in a ball mill substituted with high-purity Ar gas. . Next, a BN mold release agent was applied to a graphite mold, and a Ta plate was attached to the surface of the mold. The mixed powder was filled in the mold. This molding die was inserted into a hot press apparatus, and in a vacuum of 5 × 10 ⁻⁴ Torr or less, silicide synthesis was performed at 1250 ° C. × 2 hr, pressing force 50 kg / cm ² , and deoxygenation and decarbonization at 1350 ° C. × 5 hr. Thereafter, it was densified and sintered at 1400 ° C. × 5 hr and a pressing force of 270 kg / cm ² . The obtained sintered body was ground and polished, and was subjected to electric discharge machining to finish a target having a diameter of 260 mm and a thickness of 6 mm. When the Al concentration in the target was analyzed, it was 0.3 ppm.

  On the other hand, using a low-purity Si powder having an Al content of about 450 ppm and mixing with a high-purity W powder having a maximum particle size of 10 μm or less, a target was prepared under the same conditions as described above, and the Al concentration was analyzed. It was.

Using these two types of targets, a contact barrier layer made of W silicide is formed by sputtering, and the other is the same as in Example 1, and the Al content and pn in each W silicide contact barrier layer are used. The relationship with junction leakage current was investigated. When each barrier layer was measured by flameless atomic absorption, the Al content in each film was 2.5 × 10 ¹⁸ pieces / cm ³ , 1 × 10 ¹⁶ pieces / cm ³ , and the film thickness was about 90 nm. It is. Each measurement was performed in the same manner as in Example 1. FIG. 6 shows the measurement result of the leakage current value of the pn junction with respect to the reverse bias voltage for each diode.

In FIG. 6, curve A shows the current-voltage characteristics of a diode using a film with an Al content of 2.5 × 10 ¹⁸ pieces / cm ³ and curve B with an Al content of 1 × 10 ¹⁶ pieces / cm ^3. ing. In any film, the content of heavy metal elements other than W is 1 × 10 ¹⁷ pieces / cm ³ or less, and the alkali metal is 3 × 10 ¹⁶ pieces / cm ³ or less. As is apparent from curve B in FIG. 6, an increase in leakage current can be effectively suppressed by reducing the Al content in the film to a predetermined value or less.

Example 7
A high-purity Mo powder with a maximum particle size of 10 μm or less and a high-purity Si powder with a maximum particle size of 30 μm or less were blended so as to be 63.1 wt% Mo—Si, and mixed for 48 hours in a ball mill substituted with high-purity Ar gas. . Next, a BN mold release agent was applied to a graphite mold, and a Ta plate was attached to the surface of the mold. The mixed powder was filled in the mold. This molding die was inserted into a hot press apparatus, and in a vacuum of 5 × 10 ⁻⁴ Torr or less, silicide synthesis was performed at 1100 ° C. × 2 hr, a pressing force of 40 kg / cm ² , and deoxygenation and decarbonization at 1350 ° C. × 5 hr. Thereafter, it was densified and sintered at 1400 ° C. × 5 hr and a pressing force of 280 kg / cm ² . The obtained sintered body was ground and polished, and was subjected to electric discharge machining to finish a target having a diameter of 260 mm and a thickness of 6 mm. When the Al concentration in the target was analyzed, it was 0.4 ppm.

  On the other hand, using a low-purity Si powder having an Al content of about 450 ppm and about 120 ppm, mixing with a high-purity Mo powder having a maximum particle size of 10 μm or less, preparing a target under the same conditions as above, and analyzing the Al concentration, They were 150 ppm and 30 ppm, respectively.

Using these three types of targets, a contact barrier layer made of Mo silicide is formed by sputtering, and the rest of the diodes have the same structure as in Example 1, and the Al content and pn in each Mo silicide contact barrier layer are used. The relationship with junction leakage current was investigated. When each barrier layer was measured by flameless atomic absorption, the Al content in the film was 2 × 10 ¹⁹ pieces / cm ³ , 1 × 10 ¹⁸ pieces / cm ³ , and 1 × 10 ¹⁶ pieces / cm ³ , respectively. there were. The film thickness is about 90 nm. Each measurement was performed in the same manner as in Example 1. FIG. 7 shows the measurement results of the leakage current value of the pn junction with respect to the reverse bias voltage for each diode.

In FIG. 7, curve A has an Al content of 2 × 10 ¹⁹ pieces / cm ³ , curve B has an Al content of 1 × 10 ¹⁸ pieces / cm ³ , and curve C has an Al content of 1 × 10 ¹⁶ pieces / cm 3. ³ shows current-voltage characteristics of a diode using the film No. ³ . In any film, the content of heavy metal elements other than Mo is 5 × 10 ¹⁶ pieces / cm ³ or less, and the alkali metal is 5 × 10 ¹⁶ pieces / cm ³ or less. As is apparent from the curves B and C in FIG. 7, an increase in leakage current can be effectively suppressed by reducing the Al content in the film to a predetermined value or less.

Example 8
A high-purity Ta powder having a maximum particle size of 10 μm or less and a high-purity Si powder having a maximum particle size of 30 μm or less were blended so as to be 76.3 wt% Ta—Si, and mixed for 48 hours in a ball mill substituted with high-purity Ar gas. . Next, a BN mold release agent was applied to a graphite mold, and a Ta plate was attached to the surface of the mold. The mixed powder was filled in the mold. This molding die was inserted into a hot press apparatus, and in a vacuum of 5 × 10 ⁻⁴ Torr or less, silicide synthesis was performed at 1150 ° C. × 3 hr, pressing force 60 kg / cm ² , and deoxygenation and decarbonization at 1300 ° C. × 5 hr. Thereafter, densification and sintering were performed at 1360 ° C. × 5 hr and a pressing force of 280 kg / cm ² . The obtained sintered body was ground and polished, and was subjected to electric discharge machining to finish a target having a diameter of 260 mm and a thickness of 6 mm. When the Al concentration in the target was analyzed, it was 0.4 ppm.

  On the other hand, using a low-purity Si powder having an Al content of about 430 ppm and mixing with a high-purity Ta powder having a maximum particle size of 10 μm or less, a target was prepared under the same conditions as described above, and the Al concentration was analyzed. there were.

Using these two types of targets, a contact barrier layer made of Ta silicide is formed by sputtering, and the rest of the diodes have the same structure as in Example 1, and the Al content in each Ta silicide contact barrier layer is The relationship with the pn junction leakage current was investigated. Each barrier layer has an Al content of 4 × 10 ¹⁸ pieces / cm ³ , 2 × 10 ¹⁶ pieces / cm ³ , and a film thickness of about 90 nm. Each measurement was performed in the same manner as in Example 1. FIG. 8 shows the measurement result of the leakage current value of the pn junction with respect to the reverse bias voltage for each diode.

In FIG. 8, a curve A shows current-voltage characteristics of a diode using a film having an Al content of 4 × 10 ¹⁸ pieces / cm ³ and a curve B using an Al content of 2 × 10 ¹⁶ pieces / cm ³ . . In any film, the content of heavy metal elements other than Ta is 1 × 10 ¹⁷ pieces / cm ³ or less, and the alkali metal is 5 × 10 ¹⁶ pieces / cm ³ or less. As is apparent from the curve B in FIG. 8, an increase in leakage current can be effectively suppressed by reducing the Al content in the film to a predetermined value or less.

Example 9
A high-purity Ni powder having a maximum particle size of 10 μm or less and a high-purity Si powder having a maximum particle size of 30 μm or less were mixed so as to be 51.1 wt% Ni—Si, and mixed for 48 hours in a ball mill substituted with high-purity Ar gas. . Next, a BN mold release agent was applied to a graphite mold, and a Ta plate was attached to the surface of the mold. The mixed powder was filled in the mold. This molding die was inserted into a hot press apparatus, and in a vacuum of 5 × 10 ⁻⁴ Torr or less, silicide synthesis was performed at 750 ° C. × 3 hr, pressing force 50 kg / cm ² , deoxygenation and decarbonization at 900 ° C. × 5 hr. Thereafter, densification and sintering were performed at 940 ° C. × 5 hr and a pressing force of 280 kg / cm ² . The obtained sintered body was ground and polished, and was subjected to electric discharge machining to finish a target having a diameter of 260 mm and a thickness of 6 mm. When the Al concentration in the target was analyzed, it was 0.5 ppm.

  On the other hand, using a low-purity Si powder having an Al content of about 400 ppm and mixing with a high-purity Ni powder having a maximum particle size of 10 μm or less, a target was prepared under the same conditions as described above, and the Al concentration was analyzed. there were.

Using these two types of targets, a contact barrier layer made of Ni silicide is formed by sputtering, and the rest is the same as in Example 1 except that a diode having the same structure is used. The relationship with junction leakage current was investigated. Moreover, when each barrier layer was measured by the flameless atomic absorption method, the Al content in the film was 8 × 10 ¹⁸ pieces / cm ³ and 3 × 10 ¹⁶ pieces / cm ³ . The film thickness is about 90 nm. Each measurement was performed in the same manner as in Example 1. FIG. 9 shows the measurement result of the leakage current value of the pn junction with respect to the reverse bias voltage for each diode.

In FIG. 9, a curve A shows current-voltage characteristics of a diode using a film having an Al content of 8 × 10 ¹⁸ pieces / cm ³ and a curve B using an Al content of 3 × 10 ¹⁶ pieces / cm ³ . . In any film, the content of heavy metal elements other than Ni is 2 × 10 ¹⁷ pieces / cm ³ or less, and the content of alkali metal is 1 × 10 ¹⁶ pieces / cm ³ or less. As is apparent from the curve B in FIG. 9, an increase in leakage current can be effectively suppressed by reducing the Al content in the film to a predetermined value or less.

Example 10
A high-purity Co powder having a maximum particle size of 10 μm or less and a high-purity Si powder having a maximum particle size of 30 μm or less were mixed so as to be 51.2 wt% Co—Si, and mixed for 48 hours in a ball mill substituted with high-purity Ar gas. . Next, a BN mold release agent was applied to a graphite mold, and a Ta plate was attached to the surface of the mold. The mixed powder was filled in the mold. This molding die was inserted into a hot press apparatus, and in a vacuum of 5 × 10 ⁻⁴ Torr or less, silicide synthesis was performed at 1000 ° C. × 3 hr, pressing force 40 kg / cm ² , and deoxygenation and decarbonization at 1150 ° C. × 5 hr. Thereafter, it was densified and sintered at 1240 ° C. × 5 hr and a pressing force of 280 kg / cm ² . The obtained sintered body was ground and polished, and was subjected to electric discharge machining to finish a target having a diameter of 260 mm and a thickness of 6 mm. When the Al concentration in the target was analyzed, it was 0.6 ppm.

  On the other hand, using a low-purity Si powder having an Al content of about 320 ppm and mixing with a high-purity Co powder having a maximum particle size of 10 μm or less, a target was prepared under the same conditions as described above, and the Al concentration was analyzed. there were.

Using these two types of targets, a contact barrier layer made of Co silicide was formed by sputtering, and the rest of the diode was used in the same configuration as in Example 1 to determine the Al content in each Co silicide contact barrier layer. The relationship with the pn junction leakage current was investigated. Moreover, when each barrier layer was measured by the flameless atomic absorption method, the Al content in the film was 0.5 × 10 ¹⁹ pieces / cm ³ and 2 × 10 ¹⁶ pieces / cm ³ . The film thickness is about 80 nm. Each measurement was performed in the same manner as in Example 1. FIG. 10 shows the measurement result of the leakage current value of the pn junction with respect to the reverse bias voltage for each diode.

In FIG. 10, curve A shows the current-voltage characteristics of a diode using a film having an Al content of 0.5 × 10 ¹⁹ pieces / cm ³ and curve B using an Al content of 2 × 10 ¹⁶ pieces / cm ^3. ing. In any film, the content of heavy metal elements other than Co is 2 × 10 ¹⁷ pieces / cm ³ or less, and the content of alkali metal is 1 × 10 ¹⁶ pieces / cm ³ or less. As is apparent from curve B in FIG. 10, an increase in leakage current can be effectively suppressed by reducing the Al content in the film to a predetermined value or less.

Example 11
The relationship between the Al content in the Ti nitride contact barrier layer and the pn junction leakage current was examined using a diode having a contact barrier layer made of Ti nitride and the other structure having the same structure as in Example 1. . Here, the Ti nitride contact barrier layer was formed by an active sputtering method in a nitrogen atmosphere using three types of Ti targets having Al concentrations of 150 ppm, 10 ppm, and 3 ppm, respectively. In this active sputtering method, a direct current bipolar (DC) magnetron sputtering apparatus is evacuated to 1 × 10 ⁻⁶ Torr or less, Ar 50% + N ₂ 50% gas is introduced into the chamber at 5 × 10 ⁻³ Torr, and DC Coating is performed using a current output of 400 W (4 inch disk-shaped Ti target).

  Here, a Ti target having an Al concentration of 150 ppm was arc-melted by sponge arc obtained by a crawl method to form a Ti ingot having a diameter of 140 mm, and then hot forged to obtain a target having a predetermined shape.

  On the other hand, a Ti target having an Al concentration of 10 ppm was prepared by the same method as in Example 5.

  Further, the Ti target having an Al concentration of 3 ppm was immersed in a mixed acid obtained by mixing the Ti raw material obtained by the above-described method in a ratio of 2: 1: 1: 196 with hydrofluoric acid, nitric acid, hydrochloric acid and water for 3 minutes. After the removal of Al, an EB dissolution treatment similar to Example 5 was used as a target.

When the Al concentration in each conductive film formed by the sputter link method using these three types of targets was measured by flameless atomic absorption, 1 × 10 ¹⁹ pieces / cm ³ and 1 × 10 ¹⁸ pieces / cm, respectively. ³ and 1 × 10 ¹⁷ pieces / cm ³ . The film thickness is about 100 nm. Each measurement was performed in the same manner as in Example 1. FIG. 11 shows the measurement result of the pn junction leakage current value with respect to the reverse bias voltage for each diode.

In FIG. 11, curve A has an Al content of 1 × 10 ¹⁹ pieces / cm ³ , curve B has an Al content of 1 × 10 ¹⁸ pieces / cm ³ , and curve C has an Al content of 1 × 10 ¹⁷ pieces / cm 3. ³ shows current-voltage characteristics of a diode using the film No. ³ . In any film, the content of heavy metal elements other than Ti is 5 × 10 ¹⁶ pieces / cm ³ or less, and the content of alkali metal is 5 × 10 ¹⁶ pieces / cm ³ or less, which are sufficiently low values. As is clear from the curves B and C in FIG. 11, an increase in leakage current can be effectively suppressed by reducing the Al content in the film to a predetermined value (1 × 10 ¹⁸ ) or less.

Example 12
A contact barrier layer made of Ta nitride was formed, and other than that, using a diode having the same configuration as in Example 1, the relationship between the Al content in each Ta nitride contact barrier layer and the pn junction leakage current was investigated. It was. The contact barrier layer made of Ta nitride was formed by an active sputtering method in a nitrogen atmosphere using two types of Ta targets having an Al concentration of about 150 ppm and 1 ppm or less, respectively. In this active sputtering method, a direct current bipolar (DC) magnetron sputtering apparatus is evacuated to 1 × 10 ⁻⁶ Torr or less, Ar 50% + N ₂ 50% gas is introduced into the chamber at 5 × 10 ⁻³ Torr, and DC Coating is performed using a current output of 350 W (4 inch disk-shaped Ti target).

When each barrier layer was measured by flameless atomic absorption, the Al content in each conductive film was 4 × 10 ¹⁸ pieces / cm ³ and 1 × 10 ¹⁷ pieces / cm ³ . Each film thickness is about 80 nm. Each measurement was performed in the same manner as in Example 1. FIG. 12 shows the measurement result of the leakage current value of the pn junction with respect to the reverse bias voltage for each diode.

In FIG. 12, curve A shows the current-voltage characteristics of a diode using a film having an Al content of 4 × 10 ¹⁸ pieces / cm ³ and curve B using an Al content of 1 × 10 ¹⁷ pieces / cm ³ . . In any film, the content of heavy metal elements other than Ta is 1 × 10 ¹⁷ pieces / cm ³ or less, and the content of alkali metal is 3 × 10 ¹⁶ pieces / cm ³ or less. As is apparent from curve B in FIG. 12, an increase in leakage current can be effectively suppressed by reducing the Al content in the film to a predetermined value or less.

Example 13
A contact barrier layer made of Ti—W alloy nitride was formed, and the rest of the structure was the same as in Example 1, and the Al content in the Ti—W alloy nitride contact barrier layer, the pn junction leakage current, The relevance of was investigated. Formation of the contact barrier layer made of Ti—W alloy nitride was performed by an active sputtering method in a nitrogen atmosphere using two types of 10 wt% Ti—W composite targets having an Al concentration of about 200 ppm and 1 ppm or less, respectively. In this active sputtering method, a direct current bipolar (DC) magnetron sputtering apparatus is evacuated to 1 × 10 ⁻⁶ Torr or less, Ar 50% + N ₂ 50% gas is introduced into the chamber at 5 × 10 ⁻³ Torr, and DC Coating is performed using a current output of 420 W (4 inch disk-shaped Ti target).

When each barrier layer was measured by a flameless atomic absorption method, the Al content in the film was 5 × 10 ¹⁸ pieces / cm ³ and 2 × 10 ¹⁷ pieces / cm ³ , respectively. Each film thickness is about 80 nm. Each measurement was performed in the same manner as in Example 1. FIG. 13 shows the measurement results of the leakage current value of the pn junction with respect to the reverse bias voltage for each diode.

In FIG. 13, curve A shows the current-voltage characteristics of a diode using a conductive film with an Al content of 5 × 10 ¹⁸ pieces / cm ³ and curve B with an Al content of 2 × 10 ¹⁷ pieces / cm ^3. ing. In addition, the content of heavy metal elements other than Ti is 2 × 10 ¹⁷ pieces / cm ³ or less, and the content of alkali metal is 1 × 10 ¹⁶ pieces / cm ³ or less. As is apparent from curve B in FIG. 13, an increase in leakage current can be effectively suppressed by reducing the Al content in the film to a predetermined value or less.

Example 14
A contact barrier layer made of W nitride is formed, and other than that, using a diode having the same configuration as in Example 1, the relationship between the Al content in each W nitride contact barrier layer and the pn junction leakage current is examined. It was. The contact barrier layer made of W nitride was formed by active sputtering in a nitrogen atmosphere using two types of W targets having an Al concentration of about 170 ppm and 1 ppm or less, respectively. In this active sputtering method, a direct current bipolar (DC) magnetron sputtering apparatus is evacuated to 1 × 10 ⁻⁶ Torr or less, Ar 50% + N ₂ 50% gas is introduced into the chamber at 5 × 10 ⁻³ Torr, and DC Coating is performed using a current output of 450 W (4 inch disk-shaped Ti target). When each barrier layer was measured by flameless atomic absorption, the Al content in the film was 3 × 10 ¹⁸ pieces / cm ³ and 1 × 10 ¹⁷ pieces / cm ³ , respectively. Each film thickness is about 90 nm. Each measurement was performed in the same manner as in Example 1. FIG. 14 shows the measurement result of the leakage current value of the pn junction with respect to the reverse bias voltage for each diode.

In FIG. 14, curve A shows the current-voltage characteristics of a diode using a film with an Al content of 3 × 10 ¹⁸ pieces / cm ³ and curve B with an Al content of 1 × 10 ¹⁷ pieces / cm ³ . . In any film, the content of heavy metal elements other than W is 1 × 10 ¹⁷ pieces / cm ³ or less, and the content of alkali metal is 1 × 10 ¹⁶ pieces / cm ³ or less. As is apparent from the curve B in FIG. 14, an increase in leakage current can be effectively suppressed by reducing the Al content in the film to a predetermined value (1 × 10 ¹⁸ ) or less.

The characteristic view which shows the leakage current characteristic of the diode which formed the contact barrier layer which consists of Ti-W from which Al content differs. The characteristic view which shows the leakage current characteristic of the diode which formed the contact barrier layer which consists of Ta-Ir from which Al content differs. The characteristic view which shows the leakage current characteristic of the diode which formed the contact barrier layer which consists of Ni-Nb from which Al content differs. The characteristic view which shows the leakage current characteristic of the diode which formed the contact barrier layer which consists of Fe-W from which Al content differs. The characteristic view which shows the leakage current characteristic of the diode which formed the contact barrier layer which consists of Ti-Si from which Al content differs. The characteristic view which shows the leakage current characteristic of the diode which formed the contact barrier layer which consists of W-Si from which Al content differs. The characteristic view which shows the leakage current characteristic of the diode which formed the contact barrier layer which consists of Mo-Si from which Al content differs. The characteristic view which shows the leakage current characteristic of the diode which formed the contact barrier layer which consists of Ta-Si from which Al content differs. The characteristic view which shows the leakage current characteristic of the diode which formed the contact barrier layer which consists of Ni-Si from which Al content differs. The characteristic view which shows the leakage current characteristic of the diode which formed the contact barrier layer which consists of Co-Si from which Al content differs. The characteristic view which shows the leakage current characteristic of the diode which formed the contact barrier layer which consists of TiN from which Al content differs. The characteristic view which shows the leakage current characteristic of the diode which formed the contact barrier layer which consists of TaN from which Al content differs. The characteristic view which shows the leakage current characteristic of the diode which formed the contact barrier layer which consists of Ti-W (N) from which Al content differs. The characteristic view which shows the leakage current characteristic of the diode which formed the contact barrier layer which consists of WN from which Al content differs. Schematic which shows the structural example of the diode as a semiconductor element created in Examples 1-14.

Explanation of symbols

1 Contact barrier layer 2 p + region 3 n-type substrate 4 Al layer 5 SiO ₂

Claims (9)

Al is removed from the Ti—W raw material to prepare a W material for a magnetron sputtering apparatus having an Al concentration of 1 ppm or less. Using this Ti—W material, the Al content is 1 × 10 ¹⁸ atoms / cm ^3. A method of manufacturing a semiconductor device having a junction depth of a source-drain region of 0.3 μm or less, wherein a contact barrier or a gate electrode layer as described below is formed by a sputtering method. 2. The method of manufacturing a semiconductor device according to claim 1, wherein a junction depth of the source-drain region is 0.15 [mu] m or less. 2. The method of manufacturing a semiconductor device according to claim 1, wherein a junction depth of the source-drain region is 0.1 [mu] m or less. 4. The method of manufacturing a semiconductor device according to claim 1, wherein an Al content of the contact barrier or the gate electrode layer is 1 × 10 ¹⁷ atoms / cm ³ or less in terms of the number of atoms. It is possible to form the Al content of the contact barrier or gate electrode layer of the semiconductor element having a junction depth of the source-drain region of 0.3 μm or less to 1 × 10 ¹⁸ atoms / cm ³ or less in terms of the number of atoms, A Ti-W material for a magnetron sputtering apparatus, wherein the Al concentration is 1 ppm or less. 6. The Ti-W material for a magnetron sputtering apparatus according to claim 5, wherein the junction depth of the source-drain region is 0.15 [mu] m or less. 6. The Ti-W material for a magnetron sputtering apparatus according to claim 5, wherein the junction depth of the source-drain region is 0.1 [mu] m or less. 8. The Ti-W material for a magnetron sputtering apparatus according to claim 5, wherein an Al content of the contact barrier or the gate electrode layer is 1 × 10 ¹⁷ atoms / cm ³ or less in terms of the number of atoms. . 9. The Ti-W material for a magnetron sputtering apparatus according to claim 5, wherein the contact barrier or the gate electrode layer is made of a nitride of W.

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