TW201923842A - Method for heat-treating substrate - Google Patents

Abstract

The present invention is a method for heat-treating a substrate, the method being characterized by including: (1) a step for preparing a silicon substrate having a region with a boron concentration of 2*1019 atoms/cm3 or more; (2) a step for performing ion implantation A on a surface of the silicon substrate; and (3) a step for performing RTA heat-treatment on the silicon substrate and restoring ion implantation residual defects in the silicon substrate. This provides a method for heat-treating a substrate, the method being convenient and not generating ion implantation residual defects.

Description

Heat treatment method of substrate

The present invention relates to a method for heat treatment of a substrate, and relates to a technique for mitigating a residual defect of ion implantation that remains after applying a crystalline recovery heat treatment (RTA heat treatment) after a silicon substrate or a semiconductor substrate is implanted with atoms or ions.

In the manufacturing process of the semiconductor device, an ion implantation method is used in which impurity atoms are ionized and accelerated, and the semiconductor substrate (silicon substrate) is implanted. To form a diffusion layer in the source region and the drain region, phosphorus, arsenic, and antimony are implanted as n-type impurities, and boron and boron difluoride are implanted as p-type impurities. By implanting ions into a silicon single crystal substrate, silicon atoms at the lattice position will be ejected, and inter-lattice silicon (hereinafter referred to as I) and other vacancies (hereinafter referred to as V) will be generated, which will reduce crystallinity. When the ion implantation amount is large, the crystal structure changes, and an amorphous layer (hereinafter referred to as an amorphous layer) having a short-distance order is formed although there is no long-distance order.

After the above-mentioned ion implantation, although heat treatment is performed in order to restore the crystallinity, there is a problem that I condensation defects remain after the heat treatment and the device characteristics are deteriorated. Ion implantation residual defects are formed without being affected by the structure of the substrate. For example, they are not only a conventional planar type but also a fin structure used in a fine tip device. In addition, especially in recent years, the manufacturing process has been lowered in temperature, and there is a concern that the crystallinity cannot be sufficiently restored and defects remain.

As a method for reducing the residual defects of ion implantation, Patent Document 1 proposes a method of coating a buffer layer on the surface of a semiconductor substrate before performing ion implantation, and ion implanting from the buffer layer to take crystal defects into the buffer layer. And diffusion layer. However, the method described in Patent Document 1 requires a buffer layer to be formed before ion implantation, and there is a problem that the number of processes increases.

Further, Patent Document 2 proposes a semiconductor device substrate in which an epitaxial layer is formed by implanting carbon ions into a substrate, and the precipitation of oxygen is accelerated by carbon to form high-density crystal defects. A method for removing residual defects and reducing defects. However, the method described in Patent Document 2 requires injection of carbon that is not used in a general semiconductor process, and has a problem of low versatility.

Patent Document 3 proposes an epitaxial silicon layer having a CVD oxide film formed on a silicon substrate having a phosphorus or boron concentration of 2 × 10 ¹⁹ atoms / cm ² or more, and a wafer having carbon ions implanted on the surface. Wafer, and manufacturing method of epitaxial wafer. The CVD oxide film inside is used for epitaxial growth, from phosphorus or boron diffuses from the inside of the silicon substrate to the outside, and the atmosphere used to suppress the epitaxial growth is contaminated by doping. Carbon ions are implanted on the surface to suppress the diffusion of doping from the substrate to the substrate of the epitaxial layer. Although the CVD oxide film inside is effective in suppressing out-diffusion, it may cause the warpage of the wafer, and may have an adverse effect on the manufacturing of the device. Further, in the crystalline recovery heat treatment step after the ion implantation, although the temperature of the wafer was measured with a radiation thermometer, the temperature could not be accurately measured due to the presence of a CVD oxide film. The radiation thermometer converts the intensity of infrared rays emitted from a high-temperature object into a temperature. If the pattern is formed or the emissivity is changed, it cannot be accurately measured. Because if the device layer is formed on the wafer surface, the correct temperature cannot be measured. Therefore, although the temperature inside the wafer is measured, if the CVD oxide film is inside, it cannot be accurately measured, which causes a problem. [Previous Technical Literature]

Patent Document 1: Japanese Patent Application Laid-Open No. 5-55232 Patent Document 2: Japanese Patent Application Laid-Open No. 6-338507 Patent Literature 3: Patent Publication No. 5440693

[Problems to be Solved by the Invention] The present invention has been made in view of the problems of the conventional technology described above, and an object thereof is to provide a method for heat treatment of a substrate that has good convenience and does not cause residual defects of ion implantation. [Technical means to solve the problem]

In order to achieve the above-mentioned subject, the present invention provides a method for heat-treating a substrate, including: step one, preparing a silicon substrate having a region having a boron concentration of 2 × 10 ¹⁹ atoms / cm ³ or more; and step two, applying the silicon Ion implantation A is performed on the surface of the substrate; and step 3, RTA heat treatment is performed on the silicon substrate, so that residual defects of ion implantation of the silicon substrate are recovered.

By such a substrate heat treatment method, inter-lattice silicon (hereinafter referred to as I) introduced by ion implantation A is combined with boron present at a high concentration to prevent the aggregation of I and prevent the formation of residual defects.

The prepared silicon substrate is preferably doped at a concentration of boron at a concentration of 2 × 10 ¹⁹ atoms / cm ³ or more.

In the present invention, as the prepared silicon substrate, it is possible to use a substance in which the entire silicon substrate is doped with boron at a high concentration.

In addition, the prepared silicon substrate is formed to form a silicon epitaxial layer on the silicon substrate, and the boron concentration of the silicon epitaxial layer is preferably lower than that of the silicon substrate.

By preparing such a silicon substrate, it is possible to obtain a silicon substrate that has undergone RTA heat treatment when it is not intended to use a high-concentration boron layer in the device formation region (upper surface).

At this time, the thickness of the silicon epitaxial layer is preferably 0.01 μm or more and 20 μm or less.

With such a thickness, since the I introduced into the silicon epitaxial layer by ion implantation A can be diffused into the silicon epitaxial layer during the RTA heat treatment step and combined with boron in the silicon substrate, the ion implantation portion can be made. The amount of excess I is reduced, and the formation of residual defects can be prevented.

In addition, the prepared silicon substrate was made of the silicon substrate, and the peak concentration of boron was formed to be 2 × 10 ¹⁹ atoms / cm ³ or more and 5 × 10 by applying ion implantation B of boron or a cluster containing boron. After an area of ²¹ atoms / cm ³ or less, a silicon epitaxial layer is preferably formed on the silicon substrate.

By preparing such a silicon substrate, it is possible to obtain a silicon substrate that is suitable for the RTA heat treatment when the amount of boron on the upper and lower sides is desired and the residual defects are not formed.

At this time, the thickness of the epitaxial layer is preferably 0.01 μm or more and 20 μm or less.

With such a thickness, since the I introduced into the silicon epitaxial layer by ion implantation A can be diffused into the silicon epitaxial layer in the RTA heat treatment step, and the boron implanted by ion implantation B in the silicon substrate Due to the combination, the amount of excess I in the ion implantation portion of the ion implantation A is reduced, and the formation of residual defects can be prevented.

In addition, the prepared silicon substrate was a silicon substrate having a boron concentration of 2 × 10 ¹⁹ atoms / cm ³ or more and a boron concentration of 1 × 10 ¹² atoms / cm ³ or more and 2 × 10 ¹⁹ atoms / cm ³ or less. A silicon epitaxial layer of ³ or more and 1 × 10 ²¹ atoms / cm ³ or less is preferred.

By preparing such a silicon substrate, it is possible to obtain a silicon substrate which is suitable for the RTA heat treatment when it is desired to reduce the amount of boron below the substrate and to prevent the formation of residual defects.

At this time, the thickness of the epitaxial layer is preferably 0.01 μm or more and 100 μm or less.

With such a thickness, the presence of boron in the silicon epitaxial layer is sufficient to capture the I introduced by ion implantation A, so that the formation of defects can be prevented.

At this time, it is preferable to further form a silicon epitaxial layer having a boron concentration of 1 × 10 ¹² atoms / cm ³ or more and 2 × 10 ¹⁹ atoms / cm ³ or less on the surface of the silicon epitaxial layer.

By preparing such a silicon substrate, it is possible to obtain a silicon substrate that is subjected to RTA heat treatment when it is desired that the amount of boron on the upper and lower surfaces is small and that no residual defects are formed.

The thickness of the further formed epitaxial layer is preferably 0.01 μm or more and 20 μm or less.

By having such a thickness, I, which is introduced into the further formed silicon epitaxial layer by ion implantation A, is diffused in the further formed silicon epitaxial layer during the RTA heat treatment step, and can interact with the silicon epitaxial layer. The boron bond reduces the excess amount of I in the ion implantation portion and prevents the formation of defects.

In addition, the prepared silicon substrate is formed on the silicon substrate by forming a silicon epitaxial layer having a boron concentration of 2 × 10 ¹⁹ atoms / cm ³ or more and 1 × 10 ²¹ atoms / cm ³ or less, and further forming a boron concentration. It is better that the epitaxial layer is lower than the epitaxial layer.

By preparing such a silicon substrate, an RTA heat-treated silicon substrate can be obtained without forming residual defects of ion implantation.

In the third step, the silicon substrate treated with RTA is preferably formed without an oxide film on the surface.

With a silicon substrate heat-treated for such RTA, warpage of the wafer can be suppressed, and the temperature can be easily measured with a radiation thermometer during the RTA heat treatment.

The implantation dose of the ion implantation A is preferably 1 × 10 ¹¹ atoms / cm ² or more and 1 × 10 ¹⁶ atoms / cm ² or less.

By such an implantation dose of the ion implantation A, ions can be implanted stably, and the ion implantation can be performed to the extent that the formation of defects can be prevented by the present invention.

The RTA heat treatment is preferably performed at a temperature of 800 ° C. to 1300 ° C. for a time of 0.1 seconds to 100 seconds.

By adopting such RTA conditions, it is possible to reliably restore crystallinity and prevent the occurrence of defects, and it is possible to prevent the manufacturing process from becoming too long.

In addition, the prepared silicon substrate is preferably formed with a convex Fin structure portion on the silicon substrate.

In the present invention, such a silicon substrate can be prepared and heat-treated, and since the residual defects of ion implantation are formed without being affected by the shape of the substrate, RTA-treated silicon suitable for preventing the formation of defects in the FinFET process can be obtained. Substrate. [Contrast with the effect of the prior art]

As described above, according to the present invention, it is possible to provide a method for heat-treating a substrate that is excellent in convenience and does not cause residual defects of ion implantation. Further, according to the present case, it is possible to prevent the formation of ion implantation residual defects by using a silicon substrate having a region containing boron having a peak concentration of 2 × 10 ¹⁹ atoms / cm ³ or more and 5 × 10 ²¹ atoms / cm ³ or less. , And can obtain high yields.

As described above, it is sought to develop a substrate heat treatment method which is convenient and does not cause residual defects of ion implantation.

As mentioned above, conventional techniques must increase the number of processes or introduce carbon that is not generally used as an ion implantation element. In response to this, the inventors of the present invention have repeatedly and carefully studied the formation of simple and reliable prevention of ion implantation residual defects, and found that, for example, a peak concentration of 2 × 10 ¹⁹ atoms / cm ^{3 to} 5 × 10 ²¹ atoms / cm ^{3 is used} . A silicon substrate in the region of boron, whereby the boron can hinder the agglomeration of I and prevent the formation of residual defects of ion implantation, has completed the present invention.

That is, the present invention is a method for heat treatment of a substrate, including the following steps: preparing a silicon substrate having a region having a boron concentration of 2 × 10 ¹⁹ atoms / cm ³ or more; and performing a second step on the surface of the silicon substrate. Ion implantation A; and step three, performing RTA heat treatment on the silicon substrate to recover the residual defects of ion implantation of the silicon substrate.

Although the present invention is described in detail below, the present invention is not limited thereto.

If ions are implanted into the silicon single crystal substrate, silicon atoms at the lattice position will be ejected, and inter-lattice silicon (hereinafter referred to as I) and other vacancies (hereinafter referred to as V) will be generated. When the heat treatment is performed to restore the crystallinity, V is bonded to I or the implanted atoms, and excess I remains. Excessive I aggregates during the heat treatment to form {311} defects and poorly aligned rings. The {311} defect is a defect where I agglomerates along the {311} plane. In order to prevent the formation of defects, it is important to hinder the agglutination system of I. In the present invention, the I introduced by ion implantation is combined with boron, whereby the aggregation of I can be prevented.

[Step 1] Step 1 is a step of preparing a silicon substrate having a region having a boron concentration of 2 × 10 ¹⁹ atoms / cm ³ or more.

The I introduced by ion implantation is combined with boron, whereby the aggregation of I can be prevented. When the concentration of boron is set to a concentration of 2 × 10 ¹⁹ atoms / cm ³ or more, the formation of residual defects can be prevented.

The manufacturing method of the silicon substrate is not particularly limited, and a silicon substrate manufactured by the Czochralski Method (hereinafter referred to as the CZ method) may be used, or a floating zone method (hereinafter referred to as the Floating Zone Method) may be used. (Referred to as the FZ method).

In addition, it is preferable that the prepared silicon substrate is a product having a convex Fin structure portion formed thereon. Since the ion implantation residual defects are not formed by the shape of the substrate, they are suitable for preventing the formation of defects in the FinFET process.

Hereinafter, each aspect of the prepared silicon substrate having a high-concentration region of boron in step 1 will be described in further detail.

<Like state 1> so that the silicon substrate is prepared through boron-2 × 10 ¹⁹ atom / the doping concentration was preferably at least ³ cm to 2 × 10 ¹⁹ atom / cm ³ or more and 1 × 10 ²¹ atom / cm ³ or less is preferred. In this way, the entire silicon substrate prepared in the present invention is uniformly doped with boron at a high concentration, thereby being able to be a person having a high concentration region of boron. Such a silicon substrate can be prepared by doping boron at a high concentration when a silicon single crystal is grown by the CZ method or the FZ method, and cutting out the silicon substrate from the obtained single crystal rod. When the concentration is lower than 1 × 10 ²¹ atom / cm ³ , boron is easily introduced because the boron is dissolved in the crystal. When the concentration is 2 × 10 ¹⁹ atom / cm ³ or more, since the I introduced into the substrate by ion implantation A and boron are combined, the aggregation of I is hindered, and the formation of residual defects can be prevented.

In addition, as the prepared substrate, a silicon epitaxial layer having a lower boron concentration than that of the silicon substrate can be formed on the silicon substrate.

At this time, since the I generated in the silicon epitaxial layer by ion implantation A will rapidly diffuse, it will diffuse into the epitaxial layer during the RTA heat treatment step, and then diffuse to the silicon substrate containing high concentration boron. The I diffused into the silicon substrate is combined with boron to reduce the amount of excess I in the silicon epitaxial layer of the ion implantation portion, so that the formation of defects can be prevented. Therefore, the ion implantation portion does not need to be included in the high-concentration boron region, and the distance between the ion implantation portion and the high-concentration boron region can also be a distance.

The thickness of the epitaxial layer is preferably 0.01 μm or more and 20 μm or less. With such a thickness, I can diffuse into the epitaxial layer during the RTA heat treatment step, and can be combined with boron in the silicon substrate, thereby reducing the amount of excess I in the ion implantation portion and preventing defects more reliably. Formation.

By preparing such a silicon substrate, it is possible to obtain a silicon substrate subjected to RTA heat treatment, which is suitable when it is not desired to use a high-concentration boron layer in the device formation region (upper surface).

<Pattern 2> The prepared silicon substrate was implanted with B on the silicon substrate by ion implantation of boron or a cluster containing boron to form a peak concentration of boron of 2 × 10 ¹⁹ atoms / cm ³ or more and 5 × 10 ²¹ atoms. After the area below / cm ³ , it is better to form a silicon epitaxial layer on the silicon substrate.

I introduced into the epitaxial layer by ion implantation A diffuses to the silicon substrate by a crystalline recovery heat treatment (RTA heat treatment), and boron in the silicon substrate subjected to ion implantation B combines with I, thereby blocking the aggregation of I. The range of the peak concentration of boron is preferably 2 × 10 ¹⁹ atoms / cm ³ or more and 5 × 10 ²¹ atoms / cm ³ or less. If it is 2 × 10 ¹⁹ atoms / cm ³ or more, the formation of residual defects can be prevented, and if it is 5 × 10 ²¹ atoms / cm ³ or less, it can be prevented that it takes too much time to implant ions by ion implantation B.

In the ion implantation B, boron having a solubility higher than that of the crystal can be introduced. The ion implantation B is not particularly limited as long as the peak concentration of boron is 2 × 10 ¹⁹ atoms / cm ³ or more and 5 × 10 ²¹ atoms / cm ³ or less. The energy can be, for example, 0.1 keV to 600 keV in the case of atoms, and 3 to 100 keV / cluster in the case of using clusters. The doping amount can be adjusted according to the energy. The size of the cluster is not particularly limited as long as it can be implanted with boron. As the cluster, for example, BF ₂ , B _x H _y, etc. (x, y are numbers) can be used.

Ion implantation B can use a conventional ion implanter that has an ion source, a mass analyzer that only takes out specific ions, an accelerator that accelerates ions, and a substrate (wafer) chamber. It can also use an ion source. The plasma doping device in which the acceleration part and the substrate (wafer) are arranged in the same tank. Plasma doping devices can implant ions with lower energy than conventional ion implantation devices at high concentrations in a short time.

The thickness of the silicon epitaxial layer is preferably 0.01 μm or more and 20 μm or less. With such a thickness, the I introduced by the ion implantation A can be diffused in the epitaxial layer during the RTA heat treatment step and combined with the boron in the silicon substrate, so that the amount of excess I in the ion implanted portion can be reduced While preventing the formation of defects.

By preparing such a silicon substrate, it is possible to obtain a silicon substrate suitable for RTA treatment when the amount of boron on the upper and lower surfaces is desired and the formation of residual defects is not desired.

<Sample 3> A silicon substrate having a boron concentration of 2 × 10 ¹⁹ atoms / is formed on a silicon substrate having a boron concentration of 1 × 10 ¹² atoms / cm ³ or more and 2 × 10 ¹⁹ atoms / cm ³ or less. A silicon epitaxial layer of cm ³ or more and 1 × 10 ²¹ atoms / cm ³ or less is preferred.

The I introduced into the silicon epitaxial layer by ion implantation A is combined with the boron in the silicon epitaxial layer to prevent the aggregation of I. By setting the boron concentration of the above-mentioned silicon epitaxial layer to 2 × 10 ¹⁹ atoms / cm ³ or more, the formation of residual defects is prevented. Moreover, if it is 1 × 10 ²¹ atoms / cm ³ or less, it is preferable that defects are difficult to form during the growth of the silicon epitaxial layer. An epitaxial layer with such a high boron concentration can be formed by introducing a doping gas at a high concentration during the growth of the epitaxial layer.

The silicon epitaxial layer can be grown on the entire surface of the substrate, and can also be grown around the ion implantation portion.

The thickness of the silicon epitaxial layer is preferably from 0.01 μm to 100 μm. With such a thickness of the silicon epitaxial layer, the presence of boron is sufficient to capture the I introduced by the ion implantation A, thereby preventing the formation of defects.

By preparing such a silicon substrate, it is possible to obtain a silicon substrate that is suitable for the case where it is desired that the amount of boron below the substrate is small, but that the RTA heat treatment is not allowed when residual defects are formed.

Further, it is preferable to further form a silicon epitaxial layer having a boron concentration of 1 × 10 ¹² atoms / cm ³ or more and 2 × 10 ¹⁹ atoms / cm ³ or less on the surface of the silicon epitaxial layer.

The thickness of the further formed epitaxial layer is preferably 0.01 μm or more and 20 μm or less. With such a thickness, ion implantation I introduced into the further formed silicon epitaxial layer I is diffused in the further formed silicon epitaxial layer in the RTA heat treatment step, and can be compared with the underlying silicon epitaxial layer. The boron bonding reduces the amount of excess I in the ion implantation portion and prevents the formation of defects.

By preparing such a silicon substrate, it is possible to obtain a silicon substrate which is suitable for the case where the amount of boron on the upper and lower sides is small, and it is desired not to cause residual defects to be subjected to RTA heat treatment.

<Form 4> In the prepared silicon substrate, a silicon epitaxial layer having a boron concentration of 2 × 10 ¹⁹ atoms / cm ³ or more and 1 × 10 ²¹ atoms / cm ³ or less was formed on the silicon substrate, and then a boron concentration was further formed. It is better that the epitaxial layer is lower than the epitaxial layer. At this time, the boron concentration of the upper epitaxial layer may be lower than the boron concentration of the lower layer, and can be determined according to the purpose. The boron concentration of the silicon substrate forming the epitaxial layer may be arbitrary.

By preparing such a silicon substrate, an RTA-treated silicon substrate can be obtained without forming ion implantation residual defects.

[Step 2] Step 2 is a step of performing ion implantation A on the surface of the silicon substrate prepared in step 1.

The ion implantation A can use a conventional ion implanter that has an ion source, a mass analyzer that only takes out specific ions, an accelerator that accelerates ions, and a substrate (wafer) chamber. The ion source can also be used. The plasma doping device in which the acceleration part and the substrate (wafer) are arranged in the same tank. Plasma doping devices can implant ions with lower energy than conventional ion implantation devices at high concentrations in a short time.

The implantation dose of the ion implantation A is preferably 1 × 10 ¹¹ atoms / cm ² or more and 1 × 10 ¹⁶ atoms / cm ² or less. If it is 1 × 10 ¹¹ atoms / cm ² or more, the time of ion implantation becomes longer, and implantation can be performed more stably. When it is 1 × 10 ¹⁶ atoms / cm ² or less, the amount of I generated does not become excessive, and the formation of defects can be reliably prevented. When the ion implantation amount is large, the crystal structure changes, and an amorphous layer having no long-distance order but a short-distance order is formed, but the presence or absence of the amorphous layer is not particularly limited.

The types of atoms and clusters used for ion implantation A are not particularly limited. The present invention is effective because excess I is generated regardless of the type of atoms or clusters implanted.

The energy of the ions may be changed depending on the purpose, and is not particularly limited. For example, the energy of ions can be 0.1 keV to 10 MeV when using atoms, and 3 to 100 keV / cluster when using clusters.

[Step 3] Step 3 is a step of performing RTA heat treatment on the silicon substrate ion-implanted in step 2 to recover the residual defects of the ion implantation of the silicon substrate.

The RTA heat treatment is preferably performed at a temperature of 800 ° C. to 1300 ° C. for a time of 0.1 seconds to 100 seconds. When it is maintained at a temperature of 800 ° C. or higher and 1300 ° C. or lower for 0.1 second or longer, I is sufficiently diffused and bonded to boron, so that the occurrence of defects can be prevented more reliably. If it is within 100 seconds, the process can be prevented from becoming too long.

The RTA heat-treated silicon substrate is preferably formed without a CVD oxide film (oxide film) on the surface. Although the CVD oxide film on the surface is effective at the point of suppressing out-diffusion of doping, it may cause warpage of the wafer and may adversely affect the manufacturing of the device. In addition, in the RTA heat treatment furnace, although the temperature of the wafer is measured with a radiation thermometer, the temperature cannot be accurately measured due to the presence of a CVD oxide film. The radiation thermometer converts the intensity of infrared rays radiated from a high-temperature object into a temperature. For example, if a pattern is formed on a silicon substrate heat-treated by RTA or the emissivity is changed, it cannot be accurately measured. Since a device layer is formed on a silicon substrate (wafer), the correct temperature cannot be measured. Therefore, although the temperature on the lower surface (inside) of the silicon substrate (wafer) is measured, if a CVD oxide film is provided on the lower surface (inside). It cannot be measured correctly, causing problems.

In addition, the "surface" here refers to any surface of a silicon substrate heat-treated by RTA, and the "surface" includes an upper surface, a lower surface (inside), and the like.

As mentioned above, the present invention is a method for heat treatment of a substrate that has good convenience and does not cause residual defects of ion implantation.

Although the present invention will be specifically described below using examples and comparative examples, the present invention is not limited thereto.

[Example 1] Epitaxial silicon substrates having a boron concentration of 2 × 10 ¹⁹ atoms / cm ³ and 7 × 10 ¹⁹ atoms / cm ³ were prepared as substrates, respectively. The conductivity type, diameter, crystal orientation, resistivity of the epitaxial layer, conductivity type, and thickness of the silicon substrate are shown below.

Next, arsenic is ion-implanted A on the prepared silicon substrate. The implantation dose was 1 × 10 ¹⁵ atoms / cm ² and the energy was 400 keV. Next, in order to restore the crystallinity, the silicon substrate to be subjected to the RTA heat treatment is subjected to an RTA (Rapid Thermal Annealing) heat treatment without forming an oxide film. The temperature was 1000 ° C, the time was 10 seconds, and the atmosphere was nitrogen.

[Comparative Example 1] The substrate was prepared in the same manner as in Example 1 except that the boron concentration of the prepared silicon substrate was 1 × 10 ¹⁵ atoms / cm ³ , 6 × 10 ¹⁸ atoms / cm ^3, and 1 × 10 ¹⁹ atoms / cm ³ . Heat treatment step.

Thereafter, the substrates subjected to the RTA heat treatment in Example 1 and Comparative Example 1 were subjected to cross-section TEM (Transmission Electron Microscopy) observation of residual defects by ion implantation. The observation results are shown in FIG. 1. When the boron concentration is low, the defect layer is formed into two layers. The deep-side defect is an EOR (End Of Range) defect formed in a portion deeper than the electron range, and the shallow-side defect is a defect formed due to a high concentration of arsenic. The origin of the defects is the aggregate of I. It can be seen that, in Example 1, since the boron concentration was 2 × 10 ¹⁹ atoms / cm ³ or more, no shallow-side defect was observed. On the other hand, in Comparative Example 1, not only EOR due to arsenic, but also shallow-side defects were observed.

In addition, in order to count the density of defects, the samples after the RTA heat treatment were ground with a dimple grinder and observed by plane TEM. The results of adjusting the relationship between the boron concentration and the defect density are shown in FIG. 2. It can be seen that the defects on the shallow side decrease as the boron concentration increases. If the defect density is 5 × 10 ⁸ cm ^-3 or less, the number of defects contained in the active area of the device will be one or less, so it is considered that the device performance will not be affected.

[Example 2] The resistivity, diameter, and crystal orientation of the p-type silicon substrate used in Example 2 and Comparative Example 2 are as follows:

Next, boron is ion-implanted into B on a silicon substrate. The implantation dose was 5 × 10 ¹⁴ atoms / cm ² and the energy was 80 keV. Next, a silicon epitaxial layer is formed thereon. The conductivity type of the silicon epitaxial layer is p-type, the resistivity is 2 Ω · cm, and the thickness of the silicon epitaxial layer is 3 μm. After that, the boron concentration was measured by SIMS (Secondary Ion Mass Spectrometry). As a result, the peak concentration of boron was 2 × 10 ¹⁹ atoms / cm ³ . Then, arsenic is ion-implanted on the silicon substrate prepared as described above. The implantation dose was 1 × 10 ¹⁵ atoms / cm ² and the energy was 400 keV. Next, in order to restore crystallinity, RTA heat treatment is performed. The temperature was 1000 ° C, the time was 10 seconds, and the atmosphere was nitrogen.

[Comparative Example 2] An RTA heat treatment step was performed in the same manner as in Example ² except that ion implantation B was not performed on the silicon substrate and the implantation dose was 2.5 × 10 ¹⁴ aotms / cm ² . In addition, the peak concentration of boron measured by SIMS on the substrate subjected to ion implantation at an implantation dose of 2.5 × 10 ¹⁴ atoms / cm ² was 1 × 10 ¹⁹ atoms / cm ³ .

Thereafter, the substrates subjected to the RTA heat treatment in Example 2 and Comparative Example 2 were subjected to cross-sectional TEM observation by implanting residual defects in the ions. The observation results are shown in FIG. 3. It can be seen that in the second embodiment, since the peak concentration of boron is 2 × 10 ¹⁹ atoms / cm ³ or more, no shallow-side defect is observed. On the other hand, in Comparative Example 2, a shallow defect was observed.

[Example 3] The resistivity, diameter, and crystal orientation of the p-type silicon substrate used in Example 3 and Comparative Example 3 are as follows:

Next, a silicon epitaxial layer having a thickness of 10 nm and a boron concentration of 2 × 10 ¹⁹ atoms / cm ³ was formed on the silicon substrate. A silicon epitaxial layer having a thickness of 3 μm and a boron concentration of 1 × 10 ¹⁵ atoms / cm ³ was further formed thereon. Next, arsenic was ion-implanted on the silicon substrate prepared as described above. The implantation dose was 1 × 10 ¹⁵ atoms / cm ² and the energy was 400 keV. Next, in order to restore crystallinity, RTA heat treatment is performed. The temperature was 1000 ° C, the time was 10 seconds, and the atmosphere was nitrogen.

[Comparative Example 3] A substrate heat treatment step was performed in the same manner as in Example ³ , except that the boron concentration of the underlying silicon epitaxial layer was 1 × 10 ¹⁵ atoms / cm ³ and 1 × 10 ¹⁹ atoms / cm ³ .

After that, the substrates subjected to the RTA heat treatment in Example 3 and Comparative Example 3 were subjected to cross-sectional TEM observation by implanting residual defects in the ions. The observation results are shown in FIG. 4. It can be seen that in Example 3, since the concentration of boron was 2 × 10 ¹⁹ atoms / cm ³ or more, no shallow-side defect was observed. On the other hand, in Comparative Example 3, defects on the shallow side were observed.

As described above, it is clearly understood that the present invention is a method for heat treatment of a substrate that has good convenience and does not cause residual defects of ion implantation.

In addition, the present invention is not limited by the foregoing embodiments. The foregoing embodiments are examples, and those having substantially the same configuration as the technical idea described in the patent application scope of the present invention and achieving the same effects are all included in the technical scope of the present invention.

FIG. 1 is a transmission electron microscope image of a cross section of a silicon substrate subjected to RTA heat treatment in Example 1 and Comparative Example 1. FIG. FIG. 2 is a relationship between boron concentration and defect density in Example 1 and Comparative Example 1. FIG. FIG. 3 is a transmission electron microscope image of a cross section of a silicon substrate subjected to RTA heat treatment in Example 2 and Comparative Example 2. FIG. 4 is a transmission electron microscope image of a cross section of a silicon substrate subjected to RTA heat treatment in Example 3 and Comparative Example 3. FIG.

Claims (20)

A method for heat treatment of a substrate, comprising: step one, preparing a silicon substrate having a region having a boron concentration of 2 × 10 ¹⁹ atoms / cm ³ or more; step two, performing ion implantation A on the surface of the silicon substrate; And step three, performing RTA heat treatment on the silicon substrate to recover the residual defects of ion implantation of the silicon substrate. The method for heat-treating a substrate according to claim 1, wherein the prepared silicon substrate is doped with boron having a concentration of 2 × 10 ¹⁹ atoms / cm ³ or more. The method for heat-treating a substrate according to claim 2, wherein the prepared silicon substrate is to form a silicon epitaxial layer on the silicon substrate, and the boron concentration of the silicon epitaxial layer is lower than that of the silicon substrate. The heat treatment method for a substrate according to claim 3, wherein the thickness of the silicon epitaxial layer is 0.01 μm or more and 20 μm or less. The method for heat-treating a substrate according to claim 1, wherein the prepared silicon substrate is made of the silicon substrate, and a peak concentration of boron is formed by applying ion implantation B of boron or a cluster containing boron to a B × After a region of 10 ¹⁹ atoms / cm ³ or more and 5 × 10 ²¹ atoms / cm ³ or less, a silicon epitaxial layer is formed on the silicon substrate. The heat treatment method for a substrate according to claim 5, wherein the thickness of the epitaxial layer is 0.01 μm or more and 20 μm or less. The heat treatment method for a substrate according to claim 1, wherein the prepared silicon substrate is formed on a silicon substrate having a boron concentration of 1 × 10 ¹² atoms / cm ³ or more and 2 × 10 ¹⁹ atoms / cm ³ or less. There is a silicon epitaxial layer with a boron concentration of 2 × 10 ¹⁹ atoms / cm ³ or more and 1 × 10 ²¹ atoms / cm ³ or less. The heat treatment method for a substrate according to claim 7, wherein the thickness of the epitaxial layer is 0.01 μm or more and 100 μm or less. The heat treatment method for a substrate according to claim 7, wherein a silicon epitaxial crystal having a boron concentration of 1 × 10 ¹² atoms / cm ³ or more and 2 × 10 ¹⁹ atoms / cm ³ or less is further formed on the surface of the silicon epitaxial layer. Floor. The heat treatment method for a substrate according to claim 8, wherein a silicon epitaxial crystal having a boron concentration of 1 × 10 ¹² atoms / cm ³ or more and 2 × 10 ¹⁹ atoms / cm ³ or less is further formed on the surface of the silicon epitaxial layer. Floor. The heat treatment method for a substrate according to claim 9, wherein a thickness of the further formed epitaxial layer is 0.01 μm or more and 20 μm or less. The method for heat-treating a substrate according to claim 10, wherein the thickness of the further formed epitaxial layer is 0.01 μm or more and 20 μm or less. The method for heat-treating a substrate according to claim 1, wherein the silicon substrate is prepared to form a silicon substrate having a boron concentration of 2 × 10 ¹⁹ atoms / cm ³ or more and 1 × 10 ²¹ atoms / cm ³ or less. After a silicon epitaxial layer, a silicon epitaxial layer having a lower boron concentration than the silicon epitaxial layer is further formed. According to the method for heat-treating a substrate according to any one of claims 1 to 13, in the third step, the silicon substrate treated with RTA has no oxide film formed on the surface. The method for heat-treating a substrate according to any one of claims 1 to 13, wherein an implantation dose of the ion implantation A is 1 × 10 ¹¹ atoms / cm ² or more and 1 × 10 ¹⁶ atoms / cm ² or less. The heat treatment method for a substrate according to claim 14, wherein the implantation dose of the ion implantation A is 1 × 10 ¹¹ atoms / cm ² or more and 1 × 10 ¹⁶ atoms / cm ² or less. The heat treatment method for a substrate according to any one of claims 1 to 13, wherein the RTA heat treatment is performed at a temperature of 800 ° C or more and 1300 ° C or less for a time of 0.1 seconds or more and 100 seconds or less. The heat treatment method for a substrate according to claim 14, wherein the RTA heat treatment is performed at a temperature of 800 ° C to 1300 ° C for a time of 0.1 seconds to 100 seconds. The method for heat-treating a substrate according to any one of claims 1 to 13, wherein the prepared silicon substrate is formed with a convex Fin structure portion on the silicon substrate. The heat treatment method for a substrate according to claim 14, wherein the prepared silicon substrate is formed with a convex Fin structure portion on the silicon substrate.