JP4455441B2 - Manufacturing method of semiconductor device - Google Patents

Description

  The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a heat treatment technique.

  High integration of LSI has been achieved by miniaturization of elements constituting the LSI. With the reduction in element size, formation of a shallow pn junction, that is, formation of a shallow impurity diffusion region has become important.

  In order to form a shallow impurity diffusion region, it is important to optimize ion implantation with low acceleration energy and subsequent annealing. Boron (B) is used as the p-type impurity, and phosphorus (P) or arsenic (As) is used as the n-type impurity. However, since these impurities have a large diffusion coefficient in silicon (Si), impurities are diffused inward and outward in RTA (Rapid Thermal Anneal) processing using a halogen lamp. Therefore, it has become increasingly difficult to obtain a shallow impurity diffusion layer. When the annealing temperature is lowered in order to suppress impurity diffusion, the impurity activation rate is greatly reduced. Therefore, in the RTA process using a halogen lamp, it is difficult to form an impurity diffusion layer having a shallow junction depth (about 20 nm or less) and a low resistance.

  As a technique for instantaneously supplying energy necessary for activation to the problems described above, a flash lamp annealing method using a xenon (Xe) flash lamp has been studied. The Xe flash lamp is a tube in which Xe gas is sealed in a quartz tube or the like, and emits white light in a range of, for example, several hundred μsec to several msec by discharging electric charge stored in a capacitor or the like in a short time. It is possible. Therefore, it is possible to activate the impurities without changing the distribution of impurity ions implanted into the semiconductor layer.

  However, since the light of the flash lamp is reflected on the surface of the semiconductor substrate, the heating efficiency is deteriorated and it is difficult to sufficiently activate the impurities. When the irradiation energy of the flash lamp is increased to increase the activation rate, the thermal stress increases and the semiconductor substrate is destroyed. That is, in the conventional flash lamp annealing method, although an impurity diffusion region having a shallow junction can be formed, there is a limit to lowering the resistance of the diffusion layer.

  On the other hand, as a conventional technique, a technique of forming a light absorption film in order to efficiently absorb lamp light in an annealing process is known. Japanese Patent Application Laid-Open No. 10-26772 discloses a technique for forming a light absorption film on the surface of a gate insulating film in the manufacture of a TFT (Thin Film Transistor). However, since a light absorption film formed on the surface of the gate insulating film is used, it is difficult to perform efficient heating. Japanese Patent Laid-Open No. 2000-138177 discloses a technique for forming a light absorption film on the surface of an interlayer insulating film in the manufacture of a semiconductor device. However, since a light absorption film formed on the surface of the interlayer insulating film is used, it is still difficult to perform efficient heating.

  As described above, with the high integration of LSI, it is important to control the impurity profile with high precision, such as forming a shallow and low-resistance impurity diffusion layer. It was difficult to control well.

  The present invention has been made to solve the above-described conventional problems, and an object of the present invention is to provide a method of manufacturing a semiconductor device capable of accurately controlling an impurity profile.

The method of manufacturing a semiconductor device according to the present invention includes a step of implanting impurity element ions into a semiconductor region, and a group IV element as a predetermined element or the same conductivity type as the impurity element in the semiconductor region, and the impurity element A step of implanting ions of an element having a larger mass number to form a crystal defect region in an amorphous state, and performing annealing by irradiating light of a flash lamp to the region into which the impurity element and the predetermined element are implanted , A conductive film is formed on the semiconductor region before the step of recovering the crystal defects in the crystal defect region in the amorphous state and activating the impurity element and the step of annealing by irradiating the light of the flash lamp. And maintaining the amorphous state of the crystal defect region by performing an annealing process by irradiating with light from the flash lamp. And performing at the temperature while pre-heating the semiconductor region.

A method of manufacturing a semiconductor device according to the present invention includes the steps of forming a gate insulating film on a semiconductor substrate, forming a gate electrode on the gate insulating film, said gate electrode as a mask, the semiconductor substrate in the step of implanting ions of an impurity element, the gate electrode as a mask, the semiconductor substrate is larger mass number than the impurity element an element or the impurity element of the same conductivity type of group IV as a predetermined element A step of forming an amorphous state crystal defect region by implanting element ions ; and a step of irradiating a flash lamp light to the region into which the impurity element and the predetermined element are implanted to anneal the amorphous state crystal defect A step of recovering crystal defects in the region and activating the impurity element; and annealing by irradiating light of the flash lamp. Forming a conductive film on the semiconductor substrate before the step, and performing annealing by irradiating light from the flash lamp at a temperature at which the amorphous state of the crystal defect region is maintained. It is characterized in that the semiconductor substrate is heated in advance .

The method of manufacturing a semiconductor device according to the present invention includes a step of forming a gate insulating film on a semiconductor substrate, a step of forming a gate electrode on the gate insulating film, and forming a side wall portion on a side wall of the gate electrode. And using the gate electrode and the side wall as a mask, implanting ions of a first impurity element into the semiconductor substrate, annealing the region into which the first impurity element has been implanted, Activating the first impurity element to form a first source / drain diffusion layer; and forming the first source / drain diffusion layer, and then forming a second source on the semiconductor substrate using the gate electrode as a mask. After forming the impurity element ions and forming the first source / drain diffusion layer, the gate electrode is used as a mask to the semiconductor substrate as a predetermined group IV element or element. Implanting ions of an element having the same conductivity type as the second impurity element and having a mass number larger than that of the second impurity element to form an amorphous crystal defect region; and the second impurity element. Then, the region where the predetermined element is implanted is irradiated with light from a flash lamp to perform annealing, thereby recovering crystal defects in the amorphous crystal defect region and activating the second impurity element. A step of forming a second conductive layer on the semiconductor substrate before the step of forming a second source / drain diffusion layer shallower than the source / drain diffusion layer and the step of annealing by irradiating light of the flash lamp And .

  According to the present invention, it is possible to accurately control the impurity profile, for example, by forming a shallow and low-resistance impurity diffusion layer.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1A to FIG. 1C are cross-sectional views showing a method for manufacturing a semiconductor device according to the first embodiment of the present invention. Hereinafter, a manufacturing process of a p-type MOS transistor will be described as an example.

  First, as shown in FIG. 1A, an element isolation region 2 is formed on an n-type silicon (Si) substrate 1 in accordance with a normal method for manufacturing a p-type MOS transistor. Thereafter, a gate insulating film (silicon oxide film) 3 is formed, and a gate electrode 4 is further formed on the gate insulating film 3.

Next, as shown in FIG. 1B, germanium (Ge) ions are implanted into the surface region of the n-type silicon substrate 1 using the gate electrode 4 as a mask. The ion implantation conditions are an acceleration energy of 15 keV and a dose amount of 5 × 10 ¹⁴ cm ⁻² . By this ion implantation, a crystal defect region 5 is formed on the surface of the silicon substrate 1. For example, an amorphous crystal defect region 5 is formed. The depth of the end of the crystal defect region 5 is about 20 nm from the surface of the silicon substrate 1.

Next, boron (B) ions are implanted into the surface region of the silicon substrate 1 using the gate electrode 4 as a mask. The ion implantation conditions are an acceleration energy of 0.2 keV and a dose of 1 × 10 ¹⁵ cm ⁻² . By this ion implantation, the impurity region 6 is formed above the crystal defect region 5 so as to overlap the crystal defect region 5.

Next, as shown in FIG. 1C, the entire surface of the substrate is irradiated with light using a xenon (Xe) flash lamp. The irradiation time is 10 ms or less, and the irradiation energy density is 35 J / cm ² . By this light irradiation (flash lamp annealing), the impurity element is activated and defects in the crystal defect region 5 and the impurity region 6 are recovered, and the p-type source / drain diffusion layer 7 is obtained. In the light irradiation, it is desirable to heat the substrate to a temperature of about 400 ° C. before the light irradiation.

  Although the subsequent steps are not shown, a silicon oxide film is formed as an interlayer insulating film on the entire surface at a film forming temperature of 400 ° C. by, for example, atmospheric pressure CVD. Thereafter, contact holes are formed in the interlayer insulating film, and source / drain electrodes, gate electrodes, wirings, and the like are formed.

  FIG. 2A and FIG. 2B are cross-sectional views illustrating a manufacturing method of a comparative example of the first embodiment. In this comparative example, Ge is not ion-implanted into the silicon substrate 1, but B is ion-implanted under the same conditions as in the above-described embodiment, and then xenon flash lamp light is irradiated under the same conditions as in the above-described embodiment.

  FIG. 3 shows the concentration distribution of Ge and B obtained by the steps of FIGS. 1A to 1C, and FIG. 4 shows the concentration of B obtained by the steps of FIGS. 2A and 2B. It shows the concentration distribution.

In this embodiment, the depth at which the concentration is 10 ¹⁸ cm ⁻³ is about 55 nm for Ge and about 12 nm for B. On the other hand, in the comparative example, the depth at which the B concentration is 10 ¹⁸ cm ⁻³ is about 18 nm. That is, in this embodiment, B is distributed in a shallower region than in the comparative example. This is because the ion implantation of Ge, which is heavier than B (having a larger mass number), causes a large amount of crystal defects on the surface of the substrate, resulting in an amorphous state, and the channeling phenomenon of B is suppressed.

  Further, when the sheet resistance of the diffusion layer was measured, it was 7 kΩ / □ in the sample of the comparative example in which Ge was not ion-implanted, whereas it was 510 Ω / □ in the sample of this embodiment in which Ge was ion-implanted. It was found that the resistance of the layer was significantly reduced. Further, when the variation in resistance in the substrate surface was examined, σ = 10% in the sample of the comparative example, whereas σ <1.5% in the sample of the present embodiment, and the uniformity was improved. I found out.

  As described above, the impurity profile can be accurately controlled by combining Ge ion implantation and flash lamp annealing. Therefore, a low resistance p-type source / drain diffusion layer having a shallow junction with a depth of 20 nm or less can be formed.

  In order to investigate the reason for the decrease in the diffusion layer resistance and the improvement in the uniformity of the diffusion layer resistance, the reflectance of the silicon substrate surface was measured. FIG. 5 shows the reflection spectrum of the silicon substrate surface.

Due to the low acceleration ion implantation of B, the reflectance from Si (100) is reduced by about 10% on the short wavelength side of 300 nm or less. Furthermore, the reflectivity on the short wavelength side of 400 nm or less is reduced by several percent by ion implantation of Ge. On the other hand, the reflectivity on the long wavelength side of 450 nm or more is increased by Ge ion implantation. In Si (bare Si) without ion implantation, peaks are observed near 360 nm and 270 nm. These peaks are related to the critical points E ₁ (L _{3 ′} → L ₁ ) and E ₂ (X ₄ → X ₁ ) of the band structure. By implanting Ge ions, these two peaks disappear, suggesting that a large amount of crystal defects occurred on the substrate surface and the periodicity of the crystal was broken.

  FIG. 6 shows the emission spectrum (emission intensity distribution) of the Xe flash lamp and the W halogen lamp and the absorption characteristics of Si. It can be seen that the halogen lamp has a high emission intensity on the longer wavelength side, whereas the flash lamp has a high emission intensity in the visible light region, particularly in the region of about 250 to 500 nm. Si has a high light absorption rate in the visible light region.

  As can be seen from the above, the emission energy is more efficiently absorbed by silicon when the flash lamp is used than when the halogen lamp is used. Furthermore, by generating a large amount of crystal defects in the surface region of the silicon substrate by Ge ion implantation, the reflectance of the silicon substrate surface can be lowered in a wavelength region where the emission intensity of the flash lamp is high. That is, the absorption rate of the silicon substrate surface can be increased. Therefore, by combining Ge ion implantation and flash lamp annealing, the heating efficiency can be increased, and the impurities can be efficiently activated without destroying the profile of impurities such as B.

  FIG. 7 shows the result of examining the relationship between the irradiation energy density and the sheet resistance after the step of FIG. 1C of the present embodiment. A case (a) using a flash lamp that does not cut ultraviolet light and a case (b) using a flash lamp that cuts ultraviolet light of 400 nm or less are shown. When ultraviolet light was cut, it was found that there was about 30% power loss from the change in the sheet resistance of the impurity diffusion layer. In other words, it was found that ultraviolet light effectively heated the Si substrate under normal flash lamp irradiation.

Also, a Si substrate implanted with B under conditions of 10 keV and 5 × 10 ¹⁵ cm ⁻² , and Si implanted with B under the same conditions and then implanted with Ge under conditions of 1 keV and 5 × 10 ¹⁴ cm ^−2. Substrates were prepared, and flash lamp annealing treatment was performed on each substrate under conditions of a substrate temperature of 400 ° C. and an irradiation energy density of 35 J / cm ² . As a result, the sheet resistance of the sample in which only B was ion-implanted was 320 Ω / □, whereas the sheet resistance of the sample in which Ge and B were ion-implanted was 100 Ω / □. At this time, the depth at which the concentration was 1 × 10 ¹⁸ cm ⁻³ was about 150 nm for B and about 10 nm for Ge. That is, the entire region containing B does not contain Ge. Therefore, the above results mean that the effect of conventional pre-amorphization and the effect of increasing the activation rate of B due to the presence of Ge at a high concentration are different.

  Further, in order to prove that Ge is not an effect that exists at a high concentration, Ge is ion-implanted, followed by annealing at 550 ° C. for 1 hour to recover the crystalline state, and then B is ion-implanted. After that, a flash lamp annealing treatment was performed. The sheet resistance of the diffusion layer of this sample was measured and found to be 7 kΩ / □, and the sheet resistance value could not be reduced.

  From the above, the reduction of the sheet resistance of the impurity diffusion layer and the improvement of the uniformity of the sheet resistance due to the ion implantation of Ge have improved the recovery of crystallinity because the surface region of the Si substrate is made amorphous by Ge. In addition to this, it is considered that the heating efficiency was increased by flash lamp irradiation.

  As described above, according to the present embodiment, the impurity profile can be accurately controlled by combining Ge ion implantation and short-time light irradiation using a flash lamp. Therefore, a high-concentration shallow shallow low-resistance diffusion layer can be formed.

(Embodiment 2)
FIG. 10A to FIG. 10C are cross-sectional views illustrating a method for manufacturing a semiconductor device according to the second embodiment of the present invention. Hereinafter, a manufacturing process of a p-type MOS transistor will be described as an example.

In this embodiment, the Ge (predetermined element) ion implantation region (Ge diffusion layer) is shallower than the B (impurity element) ion implantation region (B diffusion layer). Specifically, the Ge concentration is made lower than the B concentration at the boundary (pn junction boundary) between the n-type semiconductor substrate and the p-type B diffusion layer. From another viewpoint, the position where the Ge concentration is equal to the B concentration at the boundary of the pn junction is set between the surface of the semiconductor substrate and the boundary of the pn junction. The concentration of B at the boundary of the pn junction is, for example, about 1 × 10 ¹⁸ / cm ³ . From another point of view, the position where the Ge concentration distribution is maximized is made shallower than the depth at which the B concentration is 1 × 10 ¹⁹ / cm ³ .

  First, as shown in FIG. 10A, an element isolation region 2 is formed on an n-type silicon substrate 1 in accordance with a normal method for manufacturing a p-type MOS transistor. Thereafter, a gate insulating film (silicon oxide film) 3 is formed, and a gate electrode 4 is further formed on the gate insulating film 3.

Next, as shown in FIG. 10B, Ge is ion-implanted into the surface region of the n-type silicon substrate 1 using the gate electrode 4 as a mask. The ion implantation conditions are an acceleration energy of 1 keV and a dose of 5 × 10 ¹⁴ cm ⁻² . By this ion implantation, a crystal defect region 5 is formed on the surface of the silicon substrate 1. Next, B is ion-implanted into the surface region of the silicon substrate 1 using the gate electrode 4 as a mask. The ion implantation conditions are an acceleration energy of 0.2 keV and a dose of 1 × 10 ¹⁵ cm ⁻² . By this ion implantation, the impurity region 6 is formed below the crystal defect region 5 so as to overlap the crystal defect region 5.

Next, as shown in FIG. 10C, the entire surface of the substrate is irradiated with light using a xenon (Xe) flash lamp. The irradiation time is 10 ms or less, and the irradiation energy density is 35 J / cm ² . By this light irradiation (flash lamp annealing), the impurity element is activated and defects in the crystal defect region 5 and the impurity region 6 are recovered, and the p-type source / drain diffusion layer 7 is obtained. In the light irradiation, it is desirable to heat the substrate to a temperature of about 400 ° C. before the light irradiation.

  Although the subsequent steps are not shown, a silicon oxide film is formed as an interlayer insulating film on the entire surface at a film forming temperature of 400 ° C. by, for example, atmospheric pressure CVD. Thereafter, contact holes are formed in the interlayer insulating film, and source / drain electrodes, gate electrodes, wirings, and the like are formed.

FIG. 11 shows the concentration distribution of Ge and B obtained by the steps of FIGS. 10 (a) to 10 (c). In the present embodiment, the depth at which the concentration is 10 ¹⁸ cm ⁻³ is about 10 nm for Ge and about 14 nm for B. That is, Ge is not distributed over the entire impurity region into which B is implanted, and the Ge diffusion layer is formed shallower than the B diffusion layer.

  Further, when the sheet resistance of the diffusion layer was measured, it was 960Ω / □, which was significantly lower than the case where Ge was not poured. This result means that it is different from the effect of the conventional pre-amorphization and the effect of increasing the activation rate of B due to the presence of Ge at a high concentration.

Further, when the junction leakage current was measured, it was 2 × 10 ⁻¹² A / μm ² in the first embodiment, whereas it was 6 × 10 ⁻¹⁷ A / μm ² in the present embodiment. It was found that the characteristics were greatly improved. This is presumably because the Ge diffusion layer is formed in a region shallower than the B diffusion layer, so that there is no crystal defect due to Ge in the depletion layer. In addition, when crystal defects are formed in a region deeper than the B diffusion layer, B diffusion may be induced in a heat treatment process performed later, and the transistor characteristics may deteriorate. It is possible to suppress such B diffusion.

  As described above, according to the present embodiment, the same effect as that of the first embodiment can be obtained, and since the Ge diffusion layer is shallower than the B diffusion layer, the leakage current is reduced. And B diffusion can be suppressed, and a fine transistor having excellent characteristics and reliability can be obtained.

8 and FIG. 9 show a substrate temperature of 400 ° C. and an irradiation energy density of 35 J for a Si substrate implanted with B under conditions of acceleration energy of 0.2 to 0.5 keV and a dose of 1 × 10 ¹⁵ cm ^−2. The relationship between Ge ion implantation acceleration conditions (dose amount is 5 × 10 ¹⁴ cm ⁻² ) and sheet resistance, and Ge ion implantation acceleration energy and pn when flash lamp annealing is performed under the conditions of / cm ² It is the figure which showed the relationship with junction leakage current.

  As shown in FIG. 8, the sheet resistance decreases as the acceleration energy of Ge increases. For example, when the acceleration energy of B is 0.2 keV, a sheet resistance of 1000Ω / □ or less can be obtained by injecting Ge with an acceleration energy of 0.8 keV or more. When the acceleration energy of B is 0.5 keV, a sheet resistance of 1000Ω / □ or less can be obtained by injecting Ge with an acceleration energy of 0.5 keV or more.

On the other hand, as shown in FIG. 9, the pn junction leakage current increases as the acceleration energy of Ge increases. For example, when the acceleration energy of B is 0.2 keV, the junction leakage current becomes 10 ⁻¹⁶ A / μm ² or more when the acceleration energy of Ge exceeds 4 keV. When the acceleration energy of B is 0.5 keV, the junction leakage current becomes 10 ⁻¹⁶ A / μm ² or more when the acceleration energy of Ge exceeds 6 keV.

  Accordingly, when the acceleration energy of B is 0.2 keV, the acceleration energy of Ge is preferably 0.8 keV or more and 4 keV or less, and when the acceleration energy of B is 0.5 keV, the acceleration energy of Ge Is preferably 0.5 keV or more and 6 keV or less.

For example, under the above conditions, the position where the B concentration is 10 ¹⁸ cm ⁻³ (the boundary of the pn junction) can be set in a region having a depth of 20 nm or less. Under the above conditions, the average range of Ge ion implantation (the maximum point of the Ge concentration distribution) can be made shallower than the boundary of the pn junction. Further, a value (depth) obtained by adding the standard deviation of the concentration distribution to the average range can be made shallower than the boundary of the pn junction.

In the first and second embodiments described above, Ge is ion-implanted as a group IV element into a silicon substrate (group IV semiconductor substrate), and then B is ion-implanted as an impurity element. The group IV element may be ion-implanted after the implantation. In addition to Ge, Si, Sn (tin) or Pb (lead) can be used as the group IV element. Further, the dose of IV group element, Si range causing certain level of crystal defects in the surface region of the substrate (preferably, a range of the surface region of the Si substrate in an amorphous state) may be a, 1 × 10 ¹⁴ it is preferably in the range of 1 × 10 ¹⁶ cm ^-2 or less cm ^-2 or more.

  In the first and second embodiments described above, the p-channel MOS (MIS) FET has been described. However, the same method can be applied to an n-channel MOS (MIS) FET. In this case, phosphorus (P) or arsenic (As) is used as the n-type impurity implanted into the p-type silicon substrate. In the case of an n-type impurity, it is known that in a rapid thermal annealing (RTA) process using a halogen lamp as a heat source, the carrier concentration decreases as the Ge addition amount increases, and the resistance value of the diffusion layer increases. . By using flash lamp annealing, the heating efficiency can be increased, so that the resistance value of the diffusion layer can be effectively reduced.

(Embodiment 3)
12A to 12C are cross-sectional views illustrating a method for manufacturing a semiconductor device according to the third embodiment of the present invention. Hereinafter, a manufacturing process of a p-type MOS transistor will be described as an example.

  In this embodiment, Ga is used instead of Ge as an element for forming the crystal defect region 5. The Ga (predetermined element) ion implantation region (Ga diffusion layer) is shallower than the B (impurity element) ion implantation region (B diffusion layer).

  First, as shown in FIG. 12A, an element isolation region 2 is formed on an n-type silicon substrate 1 in accordance with a normal method for manufacturing a p-type MOS transistor. Thereafter, a gate insulating film (silicon oxide film) 3 is formed, and a gate electrode 4 is further formed on the gate insulating film 3.

Next, as shown in FIG. 12B, Ga ions are implanted into the surface region of the n-type silicon substrate 1 using the gate electrode 4 as a mask. The ion implantation conditions are an acceleration energy of 1 keV and a dose of 5 × 10 ¹⁴ cm ⁻² . By this ion implantation, for example, an amorphous region is formed as the crystal defect region 5 on the surface of the silicon substrate 1. Next, B is ion-implanted into the surface region of the silicon substrate 1 using the gate electrode 4 as a mask. The ion implantation conditions are an acceleration energy of 0.2 keV and a dose of 1 × 10 ¹⁵ cm ⁻² . By this ion implantation, the impurity region 6 is formed below the crystal defect region 5 so as to overlap the crystal defect region 5.

Next, as shown in FIG. 12C, the entire surface of the substrate is irradiated with light using a xenon (Xe) flash lamp. The irradiation time is 10 ms or less, and the irradiation energy density is 35 J / cm ² . By this light irradiation (flash lamp annealing), the impurity element is activated and defects in the crystal defect region 5 and the impurity region 6 are recovered, and the p-type source / drain diffusion layer 7 is obtained. In the light irradiation, it is desirable to heat the substrate to a temperature of about 400 ° C. before the light irradiation.

  Although the subsequent steps are not shown, a silicon oxide film is formed as an interlayer insulating film on the entire surface at a film forming temperature of 400 ° C. by, for example, atmospheric pressure CVD. Thereafter, contact holes are formed in the interlayer insulating film, and source / drain electrodes, gate electrodes, wirings, and the like are formed.

FIG. 13 shows the concentration distribution of Ga and B obtained by the steps of FIGS. 12 (a) to 12 (c). In the present embodiment, the depth at which the concentration is 10 ¹⁸ cm ⁻³ is about 11 nm for Ga and about 14 nm for B. That is, Ga is not distributed over the entire impurity region into which B is implanted, and the Ga diffusion layer is formed shallower than the B diffusion layer.

  The sheet resistance of the diffusion layer was measured and found to be 850Ω / □. The lower sheet resistance than in the second embodiment is due to the activation of Ga, which is the same conductivity type as B. Further, when the junction leakage current was measured, no increase in leakage current was observed. That is, no deterioration of the pn junction characteristics due to Ga ion implantation was observed.

  As described above, also in this embodiment, it is possible to obtain the same effects as those in the first embodiment. Further, as in the second embodiment, the Ga diffusion layer is shallower than the B diffusion layer, so that the leakage current can be reduced and the B diffusion can be suppressed, and the fine characteristics and reliability are excellent. It is possible to obtain a simple transistor.

In the third embodiment described above, B is ion-implanted after ion-implanting Ga (group III element), which is the same group as B (impurity element), but conversely, the group III element is ion-implanted after ion implantation of the impurity element. May be ion-implanted. Further, as the group III element, an element heavier than the impurity element (having a larger mass number than the impurity element) can be used, and in addition to Ga, In (indium) or Tl (thallium) can be used. is there. Further, the dose of III elements, Si range causing certain level of crystal defects in the surface region of the substrate (preferably, a range of the surface region of the Si substrate in an amorphous state) may be a, 1 × 10 ¹⁴ cm It is desirable that the range be ⁻² or more and 1 × 10 ¹⁶ cm ⁻² or less.

  In the third embodiment described above, the p-channel MOS (MIS) FET has been described. However, the same method can be applied to an n-channel MOS (MIS) FET. In this case, phosphorus (P) or arsenic (As) is used as the n-type impurity implanted into the p-type silicon substrate. In this case, Sb or Bi heavier than phosphorus and arsenic (having a larger mass number than phosphorus and arsenic) can be used as an element in the same group as phosphorus and arsenic (group V element).

In the first to third embodiments described above, the irradiation energy density is 35 J / cm ² and the substrate temperature is 400 ° C. as flash lamp annealing conditions, but the substrate temperature is in the range of 200 to 550 ° C. The irradiation energy density can be changed in the range of 10 to 60 J / cm ² . The reason why the substrate temperature is set to 550 ° C. or lower is to prevent the crystal defect region from being recovered before irradiation with the flash lamp. The reason why the irradiation energy density is set to 60 J / cm ² or less is to prevent an increase in thermal stress due to excessive and rapid irradiation energy and to prevent damage such as slips and cracks in the Si substrate. The reason why the substrate temperature is set to 200 ° C. or more is that irradiation energy exceeding 60 J / cm ² is required to activate the impurities at a substrate temperature lower than 200 ° C. As a substrate preheating method, lamp heating with a halogen lamp or the like, or heater heating with a hot plate or the like can be used.

  In the first to third embodiments described above, the formation of the shallow source / drain diffusion layer, that is, the formation of the extension region has been described. However, the above-described method includes the formation of the deep source / drain diffusion layer, the polysilicon gate. The present invention can also be applied to formation of electrodes or channel regions.

  In the first to third embodiments described above, the annealing using the flash lamp as the light source has been described. However, if the maximum point of the emission intensity distribution is 600 nm or less (preferably 500 nm or less), the flash is used. It is also possible to use a light source other than a lamp. The light emission period is preferably 100 milliseconds or less, more preferably 10 milliseconds or less. An excimer laser can be used as a light source other than the flash lamp.

(Embodiment 4)
FIG. 14A to FIG. 14F are cross-sectional views showing a method for manufacturing a semiconductor device according to the fourth embodiment of the present invention. The present embodiment relates to a method for manufacturing a MOS transistor using the techniques of the first to third embodiments described above. Therefore, basically, various items described in the first to third embodiments can be applied as appropriate (the same applies to the fifth to seventh embodiments).

  First, as shown in FIG. 14A, an element isolation region 2 is formed on an n-type silicon substrate 1 in accordance with a normal MOS transistor manufacturing method. Thereafter, a gate insulating film (silicon oxide film) 3 is formed, and a gate electrode 4 is further formed on the gate insulating film 3.

Next, as shown in FIG. 14B, Ge is ion-implanted into the surface region of the silicon substrate 1 using the gate electrode 4 as a mask. The ion implantation conditions are an acceleration energy of 1 keV and a dose of 5 × 10 ¹⁴ cm ⁻² . By this ion implantation, a crystal defect region 5 is formed from the surface of the silicon substrate 1 to a depth of 10 nm. Next, B is ion-implanted into the surface region of the silicon substrate 1 using the gate electrode 4 as a mask. The ion implantation conditions are an acceleration energy of 0.2 keV and a dose of 1 × 10 ¹⁵ cm ⁻² . By this ion implantation, the impurity region 6 is formed so as to overlap the crystal defect region 5.

Next, as shown in FIG. 14C, the entire surface of the substrate is irradiated with light from a Xe flash lamp while the substrate is heated to a temperature of about 400.degree. The irradiation time is 10 ms or less, and the irradiation energy density is 35 J / cm ² . By this light irradiation, the impurity element is activated and defects in the crystal defect region 5 and the impurity region 6 are recovered, and a shallow source / drain diffusion layer 7 (extension region) adjacent to the gate electrode 4 is obtained.

Next, as shown in FIG. 14D, a silicon nitride film (SiN film) and a silicon oxide film (SiO ₂ film) are sequentially deposited by the CVD method. Subsequently, the silicon nitride film 8 and the silicon oxide film 9 are selectively left on the side wall of the gate electrode 4 by RIE to form a multi-layered side wall spacer.

Next, as shown in FIG. 14E, B is ion-implanted using a side wall spacer made of the gate electrode 4, the silicon nitride film 8 and the silicon oxide film 9 as a mask. The ion implantation conditions are an acceleration energy of 5 keV and a dose of 3 × 10 ¹⁵ cm ⁻² . By this ion implantation, a deep impurity region 10 separated from the end of the gate electrode 4 is formed. Further, B is also implanted into the gate electrode (polysilicon) by this ion implantation.

Next, as shown in FIG. 14F, the entire surface of the substrate is irradiated with light from a Xe flash lamp while the substrate is heated to a temperature of about 400.degree. The irradiation time is 10 ms or less, and the irradiation energy density is 35 J / cm ² . By this light irradiation, the impurity elements implanted with ions are activated, crystal defects such as the impurity regions 10 are recovered, and a deep source / drain diffusion layer 11 separated from the end of the gate electrode 4 is obtained.

  Although the subsequent steps are not shown, a silicon oxide film is formed as an interlayer insulating film on the entire surface at a film forming temperature of 400 ° C. by, for example, atmospheric pressure CVD. Thereafter, contact holes are formed in the interlayer insulating film, and source / drain electrodes, gate electrodes, wirings, and the like are formed.

  According to this embodiment, the heat treatment time for activating the shallow impurity region 6 adjacent to the gate electrode 4 can be shortened by using flash lamp annealing. Therefore, impurity diffusion under the gate electrode can be minimized, and the short channel effect can be suppressed. Further, since the crystal defect region is formed in the surface region of the Si substrate by Ge ion implantation before the flash lamp light irradiation, the heating efficiency is increased. Therefore, the resistance of the diffusion layer can be effectively reduced, and the current drive capability of the MOS transistor can be improved.

(Embodiment 5)
FIG. 15A to FIG. 15F are cross-sectional views showing a method for manufacturing a semiconductor device according to the fifth embodiment of the present invention. This embodiment also relates to a method for manufacturing a MOS transistor using the techniques of the first to third embodiments described above.

  First, as shown in FIG. 15A, an element isolation region 2 is formed on an n-type silicon substrate 1 in accordance with a normal MOS transistor manufacturing method. Thereafter, a gate insulating film (silicon oxide film) 3 is formed, and a gate electrode 4 is further formed on the gate insulating film 3.

Next, as shown in FIG. 15B, ions of B are implanted into the surface region of the silicon substrate 1 using the gate electrode 4 as a mask. The ion implantation conditions are an acceleration energy of 0.2 keV and a dose of 1 × 10 ¹⁵ cm ⁻² . By this ion implantation, an impurity region 6 is formed.

  Next, as shown in FIG. 15C, RTA processing using a halogen lamp is performed. The annealing conditions are a substrate temperature of 800 ° C. and a heating time of 10 seconds. By this annealing treatment, the impurity element is activated, the defects in the impurity region 6 are recovered, and a shallow source / drain diffusion layer 7 (extension region) adjacent to the gate electrode 4 is obtained.

Next, as shown in FIG. 15D, a silicon nitride film (SiN film) and a silicon oxide film (SiO ₂ film) are sequentially deposited by the CVD method. Subsequently, the silicon nitride film 8 and the silicon oxide film 9 are selectively left on the side wall of the gate electrode 4 by RIE to form a multi-layered side wall spacer.

Next, as shown in FIG. 15E, Ge is ion-implanted using a side wall spacer made of the gate electrode 4, the silicon nitride film 8, and the silicon oxide film 9 as a mask. The ion implantation conditions are an acceleration energy of 15 keV and a dose amount of 5 × 10 ¹⁴ cm ⁻² . By this ion implantation, an amorphous region (crystal defect region 5) is formed from the surface of the silicon substrate 1 to a depth of 20 nm. Next, B is ion-implanted using the gate electrode and the sidewall spacer as a mask. The ion implantation conditions are an acceleration energy of 5 keV and a dose of 3 × 10 ¹⁵ cm ⁻² . By this ion implantation, a deep impurity region 10 separated from the end of the gate electrode 4 is formed. Further, B is also implanted into the gate electrode (polysilicon) by this ion implantation.

Next, as shown in FIG. 15F, the entire surface of the substrate is irradiated with light from a Xe flash lamp while the substrate is heated to a temperature of about 400.degree. The irradiation time is 10 ms or less, and the irradiation energy density is 35 J / cm ² . By this light irradiation, the impurity elements implanted with ions are activated, crystal defects such as the impurity regions 10 are recovered, and a deep source / drain diffusion layer 11 separated from the end of the gate electrode 4 is obtained.

  Although the subsequent steps are not shown, a silicon oxide film is formed as an interlayer insulating film on the entire surface at a film forming temperature of 400 ° C. by, for example, atmospheric pressure CVD. Thereafter, contact holes are formed in the interlayer insulating film, and source / drain electrodes, gate electrodes, wirings, and the like are formed.

  According to the present embodiment, the shallow impurity diffusion layer 7 is exposed to a high temperature only in the flash lamp annealing process for activating the deep impurity region 10. Therefore, impurity diffusion under the gate electrode can be minimized and the short channel effect can be suppressed. In addition, since the number of times of flash lamp irradiation is reduced, it is possible to suppress the occurrence of thermal stress due to a rapid temperature rise. Therefore, substrate damage can be reduced and yield can be improved. In addition, since the surface region of the Si substrate is made amorphous by Ge ion implantation before flash lamp light irradiation, the crystallinity is improved and the heating efficiency is increased. Therefore, the resistance of the diffusion layer can be effectively reduced, and the current drive capability of the MOS transistor can be improved.

(Embodiment 6)
FIG. 16A to FIG. 16F are cross-sectional views showing a method for manufacturing a semiconductor device according to the sixth embodiment of the present invention. This embodiment also relates to a method for manufacturing a MOS transistor using the techniques of the first to third embodiments described above.

First, as shown in FIG. 16A, an element isolation region 2 is formed on an n-type silicon substrate 1 in accordance with a normal MOS transistor manufacturing method. Thereafter, a gate insulating film (silicon oxide film) 3 is formed, and a gate electrode 4 is further formed on the gate insulating film 3. Thereafter, a silicon nitride film (SiN film) and a silicon oxide film (SiO ₂ film) are sequentially deposited by the CVD method. Subsequently, the silicon nitride film 8 and the silicon oxide film 9 are selectively left on the side wall of the gate electrode 4 by RIE to form a multi-layered side wall spacer.

Next, as shown in FIG. 16B, B is ion-implanted using the gate electrode and the sidewall spacer as a mask. The ion implantation conditions are an acceleration energy of 5 keV and a dose of 3 × 10 ¹⁵ cm ⁻² . By this ion implantation, a deep impurity region 10 separated from the end of the gate electrode 4 is formed. Further, B is also implanted into the gate electrode (polysilicon) by this ion implantation.

  Next, as shown in FIG. 16C, RTA processing using a halogen lamp is performed. The annealing conditions are a substrate temperature of 1015 ° C. and a heating time of 10 seconds. By this annealing treatment, the impurity element is activated, the defect in the impurity region 10 is recovered, and the deep source / drain diffusion layer 11 separated from the gate electrode 4 is obtained.

  Next, as shown in FIG. 16D, the silicon oxide film 9 constituting a part of the sidewall spacer is selectively etched with hydrofluoric acid (HF).

Next, as shown in FIG. 16E, Ge is ion-implanted using the gate electrode 4 and the silicon nitride film 8 as a mask. The ion implantation conditions are an acceleration energy of 1 keV and a dose of 5 × 10 ¹⁴ cm ⁻² . By this ion implantation, a crystal defect region 5 is formed from the surface of the silicon substrate 1 to a depth of 10 nm. Next, B is ion-implanted using the gate electrode 4 and the silicon nitride film 8 as a mask. The ion implantation conditions are an acceleration energy of 0.2 keV and a dose of 1 × 10 ¹⁵ cm ⁻² . By this ion implantation, a shallow impurity region 6 adjacent to the end of the gate electrode 4 is formed.

Next, as shown in FIG. 16F, the entire surface of the substrate is irradiated with light from a Xe flash lamp while the substrate is heated to a temperature of about 400.degree. The irradiation time is 10 ms or less, and the irradiation energy density is 35 J / cm ² . By this light irradiation, the ion-implanted impurity element is activated, crystal defects such as the impurity region 6 are recovered, and a shallow source / drain diffusion layer 7 adjacent to the gate electrode 4 is obtained.

  Although the subsequent steps are not shown, a silicon oxide film is formed as an interlayer insulating film on the entire surface at a film forming temperature of 400 ° C. by, for example, atmospheric pressure CVD. Thereafter, contact holes are formed in the interlayer insulating film, and source / drain electrodes, gate electrodes, wirings, and the like are formed.

  According to this embodiment, the shallow source / drain diffusion layer 7 is formed after the deep source / drain diffusion layer 11. Therefore, the shallow impurity region 6 is not exposed to a high temperature on the order of seconds for activating the deep impurity region 10. Therefore, impurity diffusion under the gate electrode can be minimized and the short channel effect can be suppressed. In addition, since the number of times of flash lamp irradiation is reduced, it is possible to suppress the occurrence of thermal stress due to a rapid temperature rise. Therefore, substrate damage can be reduced and yield can be improved. Further, since the crystal defect region is formed in the surface region of the Si substrate by the ion implantation of Ge before the flash lamp light irradiation, the heating efficiency is increased. Therefore, the resistance of the diffusion layer can be effectively reduced, and the current drive capability of the MOS transistor can be improved.

  In the fourth to sixth embodiments described above, examples of p-type MOS transistors have been described. However, the above-described method can also be applied to n-type MOS transistors. Various modifications as described in the first to third embodiments are possible.

(Embodiment 7)
FIG. 17A to FIG. 17E are cross-sectional views showing a method for manufacturing a semiconductor device according to the seventh embodiment of the present invention.

First, as shown in FIG. 17A, a silicon oxide film (SiO ₂ film) 22 having a thickness of 200 nm is deposited on an n-type silicon substrate 21 by a CVD method. Next, as shown in FIG. 17B, the silicon oxide film 22 is patterned to form a contact hole 23 of 0.3 μm × 0.3 μm.

Next, as shown in FIG. 17C, Ge is ion-implanted into the surface region of the silicon substrate 21 using the silicon oxide film 22 as a mask. The ion implantation conditions are an acceleration energy of 15 keV and a dose amount of 5 × 10 ¹⁴ cm ⁻² . By this ion implantation, for example, an amorphous region is formed as the crystal defect region 24 on the surface of the silicon substrate 21. Next, B is ion-implanted into the surface region of the silicon substrate 21 using the silicon oxide film 22 as a mask. The ion implantation conditions are an acceleration energy of 5 keV and a dose of 5 × 10 ¹⁵ cm ⁻² . By this ion implantation, the impurity region 25 is formed below the crystal defect region 24 so as to overlap the crystal defect region 24.

  Next, as shown in FIG. 17D, a metal film 26 having a thickness of 30 nm or less is formed on the entire surface. For the metal film 26, it is desirable to use a metal capable of reducing the natural oxide film on the silicon substrate, such as Ti. In general, it is possible to use a refractory metal of group IIIa, group IVa, or group Va.

Next, with the substrate heated to a temperature of about 400 ° C., the entire surface of the substrate is irradiated with light from a Xe flash lamp. The irradiation time is 10 ms or less, and the irradiation energy density is 35 J / cm ² . By this light irradiation (flash lamp annealing), the impurity element is activated, and defects in the crystal defect region 24 and the impurity region 25 are recovered, and the diffusion layer 27 is obtained. Also, a good ohmic contact between the metal film 26 and the diffusion layer 27 can be obtained by this flash lamp annealing.

  Next, as shown in FIG. 17E, for example, an Al film (film thickness 400 n) is deposited as the low resistivity metal film 28. Further, the metal films 26 and 28 are patterned to form electrodes.

The contact resistance between the Al electrode 28 and the silicon substrate 21 obtained by the above-described process was measured and found to be 6 × 10 ⁻⁸ Ωcm ² . On the other hand, in the sample of the comparative example in which only B was ion-implanted without Ge ion implantation, the contact resistance was 3 × 10 ⁻⁷ Ωcm ² . From these results, it is understood that the contact resistance is remarkably reduced in this embodiment as compared with the comparative example.

  In general, in contact between a metal and a semiconductor, a barrier layer exists in the semiconductor, and this is a cause of contact resistance. By injecting Ge ions, crystal defects are generated on the substrate surface (amorphizing the substrate surface), whereby localized levels can be formed in the barrier layer. Thereby, even if the carriers do not cross the barrier as in the case of thermionic emission current, the carriers easily move through the levels formed in the barrier. Therefore, in this embodiment, it is considered that the contact resistance is remarkably reduced as a result of the formation of the recombination ohmic contact.

  In the above-described embodiment, the Ge (predetermined element) ion implantation step, the B (impurity element) ion implantation step, and the metal film (conductive film) 26 formation step can be performed in any order. .

  As described above, according to the present embodiment, as described in the first to third embodiments, a low-resistance shallow diffusion layer can be obtained, and a good ohmic contact can be obtained.

  Also in this embodiment, various modifications as described in the first to third embodiments are possible. For example, in this embodiment, the p-type diffusion layer is formed by ion implantation of boron (B), but it is also possible to form the n-type diffusion layer by ion implantation of phosphorus (P) or arsenic (As). It is. Further, instead of ion implantation of Ge, Si, Sn or Pb can be ion implanted as a group IV element. Further, when forming a p-type diffusion layer, it is also possible to ion-implant group III elements Ga, In or Tl instead of ion-implanting Ge. Furthermore, when forming an n-type diffusion layer, it is also possible to ion-implant Sb or Bi, which is a group V element, instead of ion-implanting Ge.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. Furthermore, the above embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining the disclosed constituent elements. For example, even if several constituent requirements are deleted from the disclosed constituent requirements, the invention can be extracted as an invention as long as a predetermined effect can be obtained.

Sectional drawing which showed the manufacturing method of the semiconductor device which concerns on the 1st Embodiment of this invention. Sectional drawing which showed the manufacturing method of the comparative example of 1st Embodiment. The figure which showed density | concentration distribution of Ge and B in the semiconductor device obtained by the process of Fig.1 (a)-FIG.1 (c). FIG. 3 is a diagram showing a concentration distribution of B in the semiconductor device obtained by the steps of FIGS. 2A and 2B. The figure which showed the reflection spectrum of the silicon substrate surface. The figure which showed the emission spectrum of Xe flash lamp and W halogen lamp, and the absorption characteristic of Si. The figure which showed the relationship between irradiation energy density and sheet resistance. The figure which showed the relationship between the acceleration energy of Ge, and sheet resistance. The figure which showed the relationship between the acceleration energy of Ge, and junction leakage current. Sectional drawing which showed the manufacturing method of the semiconductor device which concerns on the 2nd Embodiment of this invention. The figure which showed concentration distribution of Ge and B in the semiconductor device obtained by the process of Fig.10 (a)-FIG.10 (c). Sectional drawing which showed the manufacturing method of the semiconductor device which concerns on the 3rd Embodiment of this invention. FIG. 13 is a diagram showing Ga and B concentration distributions in the semiconductor device obtained by the steps of FIGS. 12 (a) to 12 (c). Sectional drawing which showed the manufacturing method of the semiconductor device which concerns on the 4th Embodiment of this invention. Sectional drawing which showed the manufacturing method of the semiconductor device which concerns on the 5th Embodiment of this invention. Sectional drawing which showed the manufacturing method of the semiconductor device which concerns on the 6th Embodiment of this invention. Sectional drawing which showed the manufacturing method of the semiconductor device which concerns on the 7th Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Silicon substrate 2 ... Element isolation region 3 ... Gate insulating film 4 ... Gate electrode 5 ... Crystal defect region 6, 10 ... Impurity region 7, 11 ... Source-drain diffused layer 8 ... Silicon nitride film 9 ... Silicon oxide film 21 ... Silicon substrate 22 ... Silicon oxide film 23 ... Contact hole 24 ... Crystal defect region 25 ... Impurity region 26, 28 ... Metal film 27 ... Diffusion layer

Claims (8)

Implanting impurity element ions into the semiconductor region;
A step of implanting ions of a group IV element as a predetermined element or an element having the same conductivity type as the predetermined element and having a mass number larger than the impurity element into the semiconductor region to form an amorphous crystal defect region; ,
Irradiating the region where the impurity element and the predetermined element are implanted with light from a flash lamp to perform annealing, recovering crystal defects in the crystal defect region in the amorphous state, and activating the impurity element;
A step of forming a conductive film on the semiconductor region before the step of performing annealing by irradiating light of the flash lamp;
With
The method of manufacturing a semiconductor device, wherein the step of performing annealing by irradiating light from the flash lamp is performed in a state where the semiconductor region is preheated at a temperature at which the amorphous state of the crystal defect region is maintained. Forming a gate insulating film on the semiconductor substrate;
Forming a gate electrode on the gate insulating film;
It said gate electrode as a mask, implanting ions of an impurity element into the semiconductor substrate,
Using the gate electrode as a mask, the semiconductor substrate is implanted with ions of a group IV element as a predetermined element or an element having the same conductivity type as the impurity element and having a mass number larger than that of the impurity element. Forming a defect region;
Irradiating the region where the impurity element and the predetermined element are implanted with light from a flash lamp to perform annealing, recovering crystal defects in the crystal defect region in the amorphous state, and activating the impurity element;
A step of forming a conductive film on the semiconductor substrate before the step of performing annealing by irradiating light of the flash lamp;
With
The method of manufacturing a semiconductor device, wherein the step of performing annealing by irradiating light of the flash lamp is performed in a state where the semiconductor substrate is preheated at a temperature at which the amorphous state of the crystal defect region is maintained. Forming a gate insulating film on the semiconductor substrate;
Forming a gate electrode on the gate insulating film, and forming a sidewall portion on the sidewall of the gate electrode ;
As the gate electrode and masking the sidewall portion, and a step of implanting ions of a first impurity element into the semiconductor substrate,
Annealing the region implanted with the first impurity element to activate the first impurity element to form a first source / drain diffusion layer;
After forming the first source-drain diffusion layer, said gate electrode as a mask, implanting ions of the second impurity element to said semiconductor substrate,
After forming the first source-drain diffusion layer, said gate electrode as a mask, the semiconductor substrate, wherein a group IV element or the second identical conductivity type and an impurity element of a predetermined element second Implanting ions of an element having a mass number larger than that of the impurity element to form an amorphous crystal defect region;
The region where the second impurity element and the predetermined element are implanted is irradiated with light from a flash lamp and annealed to recover crystal defects in the amorphous crystal defect region and activate the second impurity element. Forming a second source / drain diffusion layer shallower than the first source / drain diffusion layer;
A step of forming a conductive film on the semiconductor substrate before the step of performing annealing by irradiating light of the flash lamp;
A method for manufacturing a semiconductor device, comprising: The method of manufacturing a semiconductor device according to claim 1, wherein the light of the flash lamp has a maximum point of emission intensity distribution in a wavelength region of 600 nm or less. The method for manufacturing a semiconductor device according to claim 1 , wherein the predetermined element is selected from Si, Ge, Sn, Pb, Ga, In, Tl, Sb, and Bi. The method of manufacturing a semiconductor device according to claim 1 , wherein the flash lamp has a light emission period of 100 milliseconds or less. 4. The method of manufacturing a semiconductor device according to claim 1, wherein an irradiation energy density of the flash lamp is 10 J / cm ² or more and 60 J / cm ² or less. 5. 4. The semiconductor according to claim 3 , wherein the step of performing annealing by irradiating light of the flash lamp is performed in a state where the semiconductor substrate is preheated at a temperature at which the amorphous state of the crystal defect region is maintained. Device manufacturing method.

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