JP2009147216A - Manufacturing device of semiconductor device and manufacturing method of semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing device and a manufacturing method of a semiconductor device where, in nitriding an SiO<SB>2</SB>film on an Si substrate, a high generation efficiency of N radical and a lower generation efficiency of N<SB>2</SB><SP>+</SP>radical sufficiently nitride the surface of SiO<SB>2</SB>while preventing nitriding of SiO<SB>2</SB>/Si interface, so that shifting of a threshold voltage of a transistor can be prevented. <P>SOLUTION: In the manufacturing device of a semiconductor device, reaching of N<SB>2</SB><SP>+</SP>to an SiO<SB>2</SB>film on an Si substrate is prevented to disable nitriding of SiO<SB>2</SB>/Si interface. As a first embodiment, at least a process chamber, a radial line slot antenna, a first gas introducing opening for introducing first gas, and a second gas introducing opening for introducing second gas are provided. The process chamber is provided with a metal-made ion removing plate which is charged minus. The first gas introducing opening and second gas introducing opening are provided to the process chamber, at such position as the first gas is mixed with the second gas after it passes the ion removing plate. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a semiconductor device manufacturing apparatus and a manufacturing method.

The performance of VLSI is further improved with the increase in the degree of integration and processing speed. In order to improve such performance, it is essential to increase the capacitance of the gate insulating film. Conventionally, an SiO ₂ film has been used as the gate insulating film, and an increase in electric capacity has been realized by reducing the thickness while improving the insulating characteristics of the SiO ₂ film. However, in recent years, the thickness of the SiO ₂ film has reached about several atomic layers. For example, extremely thin films of 1.5 to ₂ nm have been used in logic devices, and it has become extremely difficult to reduce the thickness further. Therefore, a method for increasing the electric capacity by increasing the dielectric constant of the SiO ₂ film has been studied, and a SiON film in which the dielectric constant is increased by nitriding SiO ₂ is now widely used.

On the other hand, a poly-Si film doped with B (polycrystalline silicon thin film) is used for the gate electrode formed on the upper layer of the gate insulating film. However, this B diffuses into the gate insulating film, and gate insulation is performed. When the film is very thin, there is a problem that it diffuses to the channel below the gate insulating film. Since the SiON film is also effective in preventing B diffusion, for this reason, a SiON film having a dielectric constant increased by nitriding SiO ₂ is used as the gate insulating film.

However, the depth distribution of N in the SiON film is important for preventing B diffusion. In the method of thermally nitriding a conventionally used SiO ₂ film by annealing at a high temperature of about 800 to 1100 ° C. in NO and N ₂ O gas, N is mainly an SiO ₂ film that is a gate insulating film. Is introduced into the SiO ₂ / Si interface between Si and the channel Si, and is hardly introduced into the SiO ₂ film or the SiO ₂ surface. For this reason, even if B diffusion into the channel can be prevented, it is impossible to prevent B diffusion into the SiO ₂ film. Further, N introduced into the SiO ₂ / Si interface has a problem of increasing the shift of the threshold voltage of the transistor over time. Therefore, it is necessary to introduce more N into the surface side of the SiO ₂ film and to suppress N introduction to the SiO ₂ / Si interface as much as possible.

As a method for realizing this suppression, a method of radical nitriding the SiO ₂ film is currently known. Is one way to the radical nitriding, the microwave-excited plasma radical nitridation, microwave is irradiated to the mixed gas of Ar and N _2, and N ₂ dissociation or ionization, N, radicals such as N ₂ ⁺ In this method, the SiO ₂ film is nitrided. Since radicals are extremely reactive, the penetration length in the SiO ₂ film is extremely short. As a result, N in the SiO ₂ film has the highest surface concentration and shows a steep depth distribution on the SiO ₂ surface side, so that the introduction of N into the SiO ₂ / Si interface can be greatly reduced. Is possible.

However, when the thickness of the gate insulating film progresses further, in Ar / N ₂ radical nitridation of the above, inhibition of N introduction into SiO ₂ / Si interface is not sufficient, a part of N is the SiO ₂ / Si interface Introduced, there was a problem that the threshold voltage shifted.

In order to solve this problem, for example, in Patent Document 1, Xe / N ₂ , Kr / N ₂ , Ar / NH ₃ , Kr / NH ₃ , Xe / NH ₃ , Ar / N ₂ / H ₂ , Kr / A method for suppressing the introduction of N into the SiO ₂ / Si interface has been proposed by examining the types and combinations of gases constituting the plasma, such as N ₂ / H ₂ and Xe / N ₂ / H ₂ .

In the method proposed in Patent Document 1, among the types and combinations of gases, radical nitriding by NH ₃ Ar / NH ₃ using, Kr / NH ₃ or Xe / NH _3, is theoretically SiO ₂ / Si Although it was expected that the effect of preventing the introduction of N into the interface was high, non-patent document 1 clarified that it is actually the opposite effect. In the radical nitriding by a combination of _{Ar / N 2 / H 2,} Kr / N 2 / H 2 or Xe / N ₂ / H _2, with H _2, H is taken into the SiO ₂ / Si interface, As reported by Non-Patent Document 2, a threshold voltage shift is caused and the effect of suppressing the introduction of N into the SiO ₂ / Si interface is canceled out, so that a sufficient threshold voltage shift suppressing effect cannot be expected. Furthermore, radical nitriding with Kr / N ₂ has an effect of suppressing introduction of N into the SiO ₂ / Si interface, but N is only about ½ compared with conventional radical nitriding with Ar / N _2. In spite of the fact that Kr gas cannot be suppressed, it is difficult to apply it to mass production from the viewpoint of cost effectiveness because Kr gas is very expensive. Radical nitriding using Xe / N ₂ is the method having the highest effect of suppressing the introduction of N into the SiO ₂ / Si interface among the methods of Patent Document 1, but the N introduction efficiency into the SiO ₂ surface is low, In order to introduce N as much as Ar / N ₂ radical nitriding into the SiO ₂ surface, 2.5 to 3 times or more of time is required, and there is a problem that reduction in production efficiency is inevitable (non-patent) Reference 1).

A radical nitriding apparatus for performing radical nitridation using the Ar / N ₂ plasma is schematically shown in FIG. In the apparatus, a Si substrate 1 having a SiO ₂ film 2 formed on the surface thereof is disposed on a sample stage 3 in a processing chamber 5. The sample stage 3 includes a heating mechanism 4 and can freely set the sample temperature. Above the processing chamber 5, the microwave generated by the microwave generator 13 is supplied to a radical line slot antenna (RLSA) 15 through a microwave waveguide 14. A dielectric plate 16 is disposed under the radial line slot antenna (RLSA) 15. Ar gas and N ₂ gas are supplied to the space below, and Ar / N ₂ plasma is generated by microwaves. In Ar / N ₂ plasma, Ar ⁺ ions (hereinafter referred to as Ar ⁺ ), metastable excited state Ar (hereinafter referred to as Ar ^* ), and unstable excited state Ar are generated. They collide with N _2, dissociating N _2, ionization, or by exciting, N radical, N ₂ ⁺ ion radical, N ₂ metastable excited state (hereinafter N ₂ ^*), the unstable excited state N ₂ etc. are generated. However, since the lifetimes of unstable excited state Ar and unstable excited state N ₂ are extremely short, ranging from 10 ⁻⁹ sec to 10 ⁻¹² sec, collision between N ₂ and unstable excited state Ar or The nitridation of the SiO ₂ film by the stably excited N ₂ is negligible. Since this plasma is weakly ionized plasma, the majority occupies ground state Ar and N ₂ that are neither ionized nor excited.

When plasma is generated using the RLSA, a space of 2.5 cm or less immediately below the RLSA is a region where the plasma is generated (plasma generation region), and spaces farther than that are Ar, Ar ⁺ , Ar ^* , N ₂ , N, N ₂ ⁺ , N ₂ ^* are diffused regions (plasma diffusion regions). Here, the diffused N ₂ ^* reaches the surface of the SiO ₂ film, and when energy is applied to the Si—O bond, N ₂ ^* itself is neither a radical nor an excited state, and changes to a ground state N _2. Therefore, nitriding with N ₂ ^* can be almost ignored. As shown in Non-Patent Document 1, nitriding the SiO ₂ surface is mainly for N radicals having a short penetration depth, and nitriding the SiO ₂ / Si interface is mainly for N ₂ ⁺ radicals having a long penetration depth. It is.

The generation process of N radicals and N ₂ ⁺ radicals in radical nitridation using the conventional Ar / N ₂ plasma shown in FIG. 10 and the process until these radicals reach the SiO ₂ film surface or the SiO ₂ / Si interface. FIG. 13 shows the process as an energy diagram in FIG. Ar ionization energy (15.8 eV), Ar metastable excitation energy (11.6 eV), N ₂ dissociation energy (9.8 eV), ionization energy (15.6 eV), excitation energy (8.4 eV) Only when it is larger than that, energy transition occurs at the time of collision, and the reaction proceeds. In addition, only reactions with the same number of charges occur before and after the collision. 11 and 13, in Ar / N ₂ plasma, N radicals are easily generated by collision of Ar ^* and N ₂ , and N ₂ ⁺ radicals are easily generated by collision of Ar ⁺ and N _2. It is clear that

Further, the radical nitriding apparatus using Xe / N ₂ plasma disclosed in Patent Document 1 is the same apparatus as FIG. 10 showing the conventional radical nitriding apparatus described above, and Xe gas is introduced as the gas 10 introduced from the gas inlet 8. Except for the above, the configuration is the same as that of the conventional radical nitridation. FIG. 12 is a diagram showing a process of generating N radicals and N ₂ ⁺ radicals in radical nitridation using Xe / N ₂ plasma disclosed in Patent Document 1. FIG. 14 shows the generation of N radicals or N ₂ ⁺ radicals in the Xe / N ₂ radical nitridation disclosed in Patent Document 1, and the process until these radicals reach the SiO ₂ film surface or the SiO ₂ / Si interface. FIG. The ionization energy of Xe (12.1 eV) and the metastable excitation energy of Xe (8.5 eV) are slightly smaller than those of Ar. For this reason, generation of N radical due to collision between Xe ^* and N ₂ and generation of N ₂ ⁺ due to collision between Xe ⁺ and N ₂ do not occur. In addition, N radicals and N ₂ ⁺ radicals are not generated once through N ₂ ^* . The molecule having the highest probability of collision of N ₂ ⁺ generated in this way is the most abundant ground state Xe, but the ionization energy of Xe is smaller than the ionization energy of N _2. When N ₂ ⁺ and Xe collide, N ₂ ⁺ changes to N ₂ and a reaction occurs in which Xe is ionized to Xe ⁺ . Naturally, such a reaction does not occur in the collision between N ₂ ⁺ and Ar. This is the reason why the generation efficiency of N ₂ ⁺ is reduced in radical nitridation using Xe / N ₂ plasma. Xe has the effect of reducing N ₂ ^{+ in} this way, but in the conventional Xe / N ₂ radical nitridation, the efficiency of N introduction to the SiO ₂ surface is low because the generation efficiency of N radicals also decreases. In order to introduce as much N as the Ar / N ₂ radical nitridation into the SiO ₂ surface, 2.5 to 3 times or more of time is required, and the problem that the production efficiency decreases is unavoidable.

That is, in radical nitridation, N radicals efficiently nitride the SiO ₂ surface as disclosed in Non-Patent Document 1 above, but simultaneously generated N ₂ ⁺ radicals have a deep penetration length and a SiO ₂ / Si interface. Is increased to increase the threshold voltage shift of the transistor. It is important to generate as much N radicals that nitride the SiO ₂ surface as possible and to suppress the generation of N ₂ ⁺ radicals that nitride the SiO ₂ / Si interface as much as possible. However, as described above, radical nitridation using conventional Ar / N ₂ plasma is
・ A large amount of N radicals can be generated by collision between Ar ^* and N ₂ ,
There is a problem that a large amount of N ₂ ⁺ radicals are generated due to collision between Ar ⁺ and N ₂ , while radical nitriding using Xe / N ₂ plasma shown in Patent Document 1
Can be reduced N ₂ ⁺ radicals by the · Xe and N ₂ ⁺ radical collision,
There is a problem that the generation efficiency of N radicals due to collision between Xe ^* and N ₂ is also reduced.

Therefore, there is a strong demand to reduce the N introduction effect to the SiO ₂ / Si interface as much as possible without reducing the N introduction effect to the SiO ₂ surface. In other words, there is a strong demand for reducing the N ₂ ⁺ radical production efficiency as much as possible without reducing the N radical production efficiency.
JP 2006-245528 A K. Kawase et al, "Control of Nitrogen Depth Profile near Silicon Oxynitride / Si (100) Interface Formed by Radial Nitridation", Jap. J. et al. Appl. Phys. August 2006, vol. 45, p. 6203-6209 N. Kimizuka, K. et al. Yamaguchi, K .; Imai, T .; Iisuka, C.I. T.A. Liu, R.A. C. Keller, T .; Horiuchi, Symp. VLSI Technology, 2000, p. 92

The present invention has been made in order to solve the above-described problem. In manufacturing a semiconductor device having a SiON film on a Si substrate, the introduction of N into the SiO ₂ surface is not reduced, and the SiON / Si interface is reduced. An object of the present invention is to provide a semiconductor device manufacturing method in which N introduction is suppressed.

  That is, a first aspect of the present invention is a semiconductor device comprising at least a processing chamber, a radial line slot antenna, a first gas introduction port for introducing a first gas, and a second gas introduction port for introducing a second gas. The processing chamber is provided with a negatively charged metal ion removal plate, the first gas inlet and the second gas inlet are provided in the processing chamber, and the first gas is ion-removed. The present invention relates to a semiconductor device manufacturing apparatus provided at a position where it is mixed with a second gas after passing through a plate.

  As a second aspect of the present invention, in the semiconductor device manufacturing apparatus, a rectifying plate made of an insulator and a third gas introduction port for introducing a third gas are further introduced into a processing chamber of the semiconductor device manufacturing apparatus. The third gas introduction port is provided at a position where the first gas and the second gas that have passed through the ion removal plate are mixed and passed through the rectifying plate and then mixed with the third gas.

  As a third aspect of the present invention, a processing chamber, a radial line slot antenna, a first gas introduction port for introducing a first gas, a second gas introduction port for introducing a second gas, A semiconductor device manufacturing apparatus including at least a third gas introduction port for introducing gas, wherein the processing chamber includes a rectifying plate made of an insulator, and includes a first gas introduction port, a second gas introduction port, and a third gas introduction plate. The gas introduction port is provided in the processing chamber, and the third gas introduction port is provided at a position where the mixed gas of the first gas and the second gas is mixed with the third gas after passing through the rectifying plate. It relates to a manufacturing apparatus.

The present invention is, for example, a method for manufacturing a semiconductor device in which a SiO ₂ film on a Si substrate is nitrided by using the semiconductor device manufacturing apparatus according to the first aspect having the above-described configuration. Ar plasma generation step for generating plasma containing at least ions and metastable excited Ar molecules, and Ar ion removal step for removing Ar ions by passing the plasma through a negatively charged metal ion removal plate A radical generating step of causing N ₂ molecules to collide with metastable excited Ar molecules contained in the plasma passed through the ion removal plate to generate N radicals, and nitriding for nitriding the SiO ₂ film by the generated N radicals The present invention relates to a method for manufacturing a semiconductor device including at least steps in this order.

  The method for manufacturing a semiconductor device further includes a rectification step for passing the rectifying plate after the radical generation step and before the nitriding step, and a contact step for contacting the Xe gas with the plasma that has passed through the rectifying plate. It is good also as an aspect.

The present invention also relates to a method of manufacturing a semiconductor device for nitriding a SiO ₂ film on a Si substrate, wherein plasma containing at least N radicals and N ₂ ⁺ radicals is generated by a mixed gas of Ar gas and N ₂ gas N plasma generation step to be performed, a rectification step to pass the generated plasma through the rectification plate, a contact step to contact the Xe gas with the plasma that has passed through the rectification plate, and nitriding the SiO ₂ film by plasma composed of N radicals The present invention relates to a method of manufacturing a semiconductor device including at least the nitriding step in this order.

N radicals are the majority of the radical species that reach the SiO ₂ film on the Si substrate, and N ₂ ⁺ ion radicals are negligible. Since nitridation by N ₂ ⁺ radicals having a long penetration depth is suppressed, nitriding at the SiO ₂ / Si interface is extremely small. Further, since nitridation by N radicals having a short penetration depth occupies most, only the SiO ₂ surface is efficiently nitrided. As a result, the shift of the threshold voltage can be suppressed, sufficient B diffusion can be prevented, and the dielectric constant of the gate insulating film can be increased, that is, the film thickness can be reduced.

The present invention provides a semiconductor device manufacturing apparatus that can be suitably used for radical nitridation of a SiO ₂ film formed on a Si substrate. In order to generate a large amount of N radicals and reduce N ₂ ⁺ radicals, These three methods and an apparatus for achieving the three methods are provided.
(1) By removing Ar ⁺ from the Ar / N ₂ plasma, N ₂ ⁺ is prevented from being generated by Ar ⁺ while generating a large amount of N radicals by Ar ^* .
(2) After generating a large amount of N radicals and N ₂ ⁺ radicals by Ar / N ₂ plasma, Xe and N ₂ ⁺ radicals collide to reduce N ₂ ⁺ .
(3) Suppression and reduction of N ₂ ⁺ production by the methods (1) and (2) above.

That is, in the first aspect of the semiconductor device manufacturing apparatus, which is a semiconductor device manufacturing apparatus according to the present invention, plasma is generated by Ar gas, Ar ions are removed, and only the excited Ar is allowed to pass through. A removal plate is provided, and by mixing N ₂ gas only with substantially excited Ar, a large amount of N radicals are generated and generation of N ₂ ⁺ radicals is reduced.

According to a second aspect of the present invention, the semiconductor device manufacturing apparatus includes a rectifying plate in addition to the ion removal plate. In this embodiment, a plasma is generated with Ar gas, and then, as described above, Ar ions are removed by a metal ion removing plate that allows only Ar in the excited state to pass, and substantially consists only of Ar in the excited state. By mixing N ₂ gas with plasma, a large amount of N radicals are efficiently generated, and the generation of N ₂ ⁺ radicals is reduced. After that, it is further passed through a rectifying plate made of an insulator and mixed with Xe gas, so that a slight amount of remaining N ₂ ⁺ radicals collide with Xe in the ground state, and Xe is ionized so that N ₂ ⁺ is grounded. By changing the state to N ₂ , it is possible to further reduce N ₂ ⁺ radicals.

In a third aspect of the present invention, the semiconductor device manufacturing apparatus is provided with a rectifying plate made of an insulator, and plasma is generated with a mixed gas of Ar gas and N ₂ gas, so that N radicals and N ₂ ⁺ A large amount of radicals are generated, and after passing through the rectifying plate made of the insulator, they are mixed with Xe gas, so that N ₂ ⁺ radicals collide with Xe in the ground state, and Xe is ionized to cause N ₂ ^By changing ⁺ to N ₂ in the ground state, N ₂ ⁺ radicals can be reduced.

Incidentally, without mixing with a rare gas such as Ar, in the method of generating plasma with 100% N ₂ gas, by the N ₂ is ionized to produce a pair of N ₂ ⁺ and electrons, plasma is generated . Therefore, in principle, it is impossible to suppress the generation of N ₂ ⁺ radicals that nitride the SiO ₂ / Si interface. However, in a plasma using a mixed gas of a rare gas and N ₂ , plasma is generated by generating a pair of rare gas ions and electrons, and therefore N ₂ ⁺ radical generation is not essential for plasma generation. . That is, in order to generate plasma with low N ₂ ⁺ radical generation efficiency, it becomes possible only by using a mixed gas with a rare gas.

  Hereinafter, the present invention will be described in more detail. In the following description of the embodiments, the description is made with reference to the drawings. In the drawings of the present application, the same reference numerals denote the same or corresponding parts.

<Semiconductor device manufacturing equipment>
The semiconductor device manufacturing apparatus of the present invention includes at least one of an ion removal plate and a rectifying plate. By providing at least one of the ion removal plate and the rectifying plate, Ar ⁺ can be changed to Ar in the ground state, and the majority of N radicals are nitride radical species that reach the SiO ₂ film provided on the Si substrate. Thus, the N ₂ ⁺ ion radical can be minimized. Further, since nitridation by N ₂ ⁺ radicals having a long penetration depth is suppressed, nitridation at the SiO ₂ film / Si substrate interface is extremely reduced. Further, since nitridation by N radicals having a short penetration depth occupies most, only the SiO ₂ surface is efficiently nitrided. As a result, the shift of the threshold voltage can be suppressed, sufficient B diffusion can be prevented, and the dielectric constant of the gate insulating film can be increased, that is, the film thickness can be reduced.

<Radial line slot antenna (RLSA)>
The radial line slot antenna is not particularly limited as long as a desired low electron temperature and high density plasma can be generated. For example, RLSA capable of generating a low electron temperature high density plasma of 0.2 eV to 2 eV can be used.

<Dielectric plate>
In the present invention, the dielectric plate is disposed so as to cover the entire surface of the RLSA. For example, a quartz plate can be used as the dielectric. The thickness of the dielectric plate may be set to 0.5 mm to 10 mm, for example, from the plasma generation efficiency.

<Ion removal plate>
Radical nitriding apparatus of the present invention, by providing the ion removal plate, can be removed Ar ^+, for Ar ⁺ and the generation of N ₂ ⁺ by collision of N ₂ is suppressed, SiO ₂ by N ₂ ⁺ Nitriding at the film / Si substrate interface is suppressed, and a shift in threshold voltage of the transistor can be suppressed.

The ion removal plate is a plate made of a metal such as Al, Al alloy, SUS, or Cr, and has a large number of holes, and a negative bias voltage is applied thereto. For example, the ion removal plate can be used by forming holes having an average pore diameter of 200 μm to ² mm so as to be 4 / cm ^{2 to} 20 / cm ² . The negative bias voltage to be applied is not particularly limited as long as Ar ⁺ can be returned to the ground state. However, by applying a voltage of 1 to 100 V, Ar ⁺ ions can be efficiently generated. It can be removed from the plasma.

  The thickness of the ion removal plate is not particularly limited as long as the voltage can be applied. For example, a plate of 0.5 mm to 5 mm is preferably used.

<Rectifying plate>
When the rectifying plate is provided in the present invention, the gas inlet for introducing the Xe gas can be separated from the plasma generation region, and Ar ^* and N ₂ can be efficiently contacted upstream of the rectifying plate. ₂ can be dissociated to generate N radicals efficiently. Further, in the downstream of the rectification plate, Ar ^* and N and N ₂ ⁺ generated by the _second collision, can be brought into contact with and Xe efficiently, can be a N ₂ ⁺ and N ₂ of the ground state, N _The amount of ²⁺ reaching the SiO ₂ film / Si substrate interface can be suppressed. Further, downstream of the rectifying plate, it is possible Ar ⁺ is to be changed to Ar in the ground state by colliding with Ar ⁺ and Xe, and Ar ⁺ from a position in which a rectifying plate in the lower (SiO ₂ film surface side) it is possible to suppress the generation of N ₂ ⁺ by collision with N _2. As a result, nitridation at the SiO ₂ film / Si substrate interface due to N ₂ ⁺ is suppressed, and a shift in the threshold voltage of the transistor is suppressed.

The rectifying plate is, for example, a plate made of an insulator such as quartz glass, ceramic, or aluminum oxide, and has a large number of holes having an average hole diameter of 200 μm to 2 mm so as to be 4 / cm ^{2 to} 20 / cm ^2. Can be used.

  Hereinafter, the present invention will be described in more detail with reference to embodiments, but the present invention is not limited thereto.

<Embodiment 1>
FIG. 1 shows a schematic diagram of an apparatus for manufacturing an SiO ₂ film semiconductor device according to Embodiment 1 of the present invention. In the processing chamber 5, the Si substrate 1 having the SiO ₂ film 2 formed on the surface is disposed on the sample stage 3. The sample stage 3 includes a heating mechanism 4 and can freely set the sample temperature. For example, it is kept at room temperature to about 500 ° C.

A microwave generator 13 is provided above the processing chamber 5, and the microwave generated by the microwave generator 13 is supplied to a radial line slot antenna (RLSA) 15 through a waveguide 14. For example, a microwave of 2.45 to 8.3 GHz is irradiated at a power density of about 0.5 to ⁵ W / cm ² . A dielectric plate 16 is disposed immediately below the radial line slot antenna (RLSA) 15, and an ion removal plate 17 is disposed at a distance of about 2.5 cm or more from the RLSA. Ar gas (gas 10) is supplied as the first gas from the first gas introduction port 8 to the space divided by the RLSA and the ion removal plate 17, and Ar plasma is generated by the microwave supplied to the processing chamber 5. To do. At this time, the processing chamber 5 is set to a pressure of about 0.1 to 100 Pa, for example. Ar ⁺ and Ar ^* are generated in the Ar plasma, but the majority of the Ar plasma is ground state Ar that is not ionized or excited. In the case of plasma generated using RLSA, a space up to 2.5 cm or less immediately below RLSA (a space up to about 2 to 3 cm or less directly below RLSA depending on the dielectric plate) is a region where plasma is generated (plasma generation). In the region 19), the space farther than that is a region (plasma diffusion region 20) where generated Ar ⁺ and Ar ^* diffuse.

The ion removal plate is a metal plate with a large number of holes, and a negative bias is applied. Since the processing chamber 5 is exhausted from below by the exhaust pump 6, Ar ⁺ , Ar ^* , and Ar in the ground state tend to flow downward through the ion removal plate. However, since the ion removal plate is negatively charged, Ar ⁺ is attracted to the ion removal plate, and is brought into contact with the ion removal plate to be supplied with electrons, thereby changing to Ar in the ground state. For this reason, Ar ⁺ remains in the form of ions and cannot pass through the ion removal plate. Accordingly, only Ar ^* and the ground state Ar pass through the ion removal plate.

A second gas introduction port 11 is provided in a space below the ion removal plate 17 and N ₂ gas is supplied as the gas 9 (second gas), so that collision between N _{2 in} the ground state and Ar ^* occurs. . In the collision between the ground state N ₂ and the ground state Ar, momentum is merely exchanged, and N ₂ is not ionized or excited, and can be ignored. Ar and N ₂ are supplied, for example, at a volume flow ratio of about 90:10. The supplied rare gas is recovered by the rare gas recovery device 7 and sent from the rare gas recovery port 12 to the purification device for recycling. By using the rare gas recovery device in this way, an increase in cost can be avoided even when expensive Xe is used.

FIG. 4 is a diagram showing a process of generating N radicals and N ₂ ⁺ radicals in Embodiment 1 of the present invention. FIG. 7 shows the processes until the N radicals or N ₂ ⁺ radicals are generated and the radicals reach the SiO ₂ film 2 surface or the SiO ₂ film 2 / Si substrate 1 interface in the first embodiment of the present invention. FIG. Comparing Figure 11 and Figure 4 or Figure 13 and Figure 7, Ar ^* the generation of N radicals by collision of N ₂ takes place in the same manner but, Ar ⁺ and N ₂ or Ar ⁺ and N ₂ ^* in accordance N ₂ ⁺ a Since generation does not occur, it can be seen that the generation efficiency of N ₂ ⁺ radicals decreases. In this way, production efficiency was maintained by reducing the amount of N ₂ ⁺ that nitrides the SiO ₂ film 2 / Si substrate 1 interface while maintaining the amount of N radicals that nitride the SiO ₂ surface. The threshold voltage shift can be reduced.

<Embodiment 2>
FIG. 2 is a diagram showing an apparatus for manufacturing a semiconductor device having a SiO ₂ film according to Embodiment 2 of the present invention. In the processing chamber 5, the Si substrate 1 having the SiO ₂ film 2 formed on the surface is disposed on the sample stage 3. The sample stage 3 includes a heating mechanism 4 and can freely set the sample temperature. For example, it is kept at room temperature to about 500 ° C.

Above the processing chamber 5, the microwave generated by the microwave generator 13 is supplied to the RLSA 15 (radial line slot antenna) via the microwave waveguide 14. For example, a microwave of 2.45 to 8.3 GHz is irradiated at a power density of about 0.5 to ⁵ W / cm ² . A dielectric plate 16 is disposed immediately below the RLSA 15. Further, the rectifying plate 18 is disposed under the RLSA 15 with a distance of about 2.5 cm or more. Ar gas is supplied from the first gas inlet 8 as the gas 10 to the space between the RLSA 15 and the rectifying plate 18, and N ₂ gas is supplied as the gas 11 (second gas) from the second gas inlet 9. Ar / N ₂ plasma is generated by the microwave. The generation of these plasmas is performed under a pressure of about 0.1 to 100 Pa, for example. Ar ⁺ , Ar ^* , N, N ₂ ⁺ and N ₂ ^* are generated in the Ar / N ₂ plasma. However, the majority occupies ground state Ar and N ₂ that are neither ionized nor excited. In the case of a plasma generated using RLSA, a space of 2.5 cm or less immediately below RLSA is a region where plasma is generated (plasma generation region 19), and a space farther than that is generated Ar ⁺ , Ar ^*. , N, N ₂ ⁺ , N ₂ ^* are diffused regions (plasma diffusion regions 20).

The rectifying plate is a plate made of an insulating material with a large number of holes. Since the processing chamber 5 is exhausted from below by the exhaust pump 6, Ar, Ar ⁺ , Ar ^* , N ₂ , N, N ₂ ⁺ , and N ₂ ^* pass through the rectifying plate and are below (in a direction away from the RLSA). Flowing into. Xe gas is supplied as gas 21 (third gas) from the third gas inlet 22 into the space below the rectifying plate, and these molecules that have passed through the rectifying plate collide with Xe in the ground state. When N ₂ ⁺ collides with Xe in the ground state, Xe is ionized and N ₂ changes to the ground state. Since Ar ⁺ also collides with Xe in the ground state, Xe is ionized, and Ar ⁺ changes to Ar in the ground state. Therefore, generation of N ₂ ⁺ due to collision between Ar ⁺ and N ₂ newly occurs in this space. There is nothing. Ar, N ₂ , and Xe are supplied at a volume flow ratio of about 90: 10: 5, for example. Note that, as in the first embodiment, the supplied rare gas is recovered by the rare gas recovery device 7, sent from the rare gas recovery port 12 to the purification device, and recycled.

FIG. 5 is a diagram showing a process of generating N radicals and N ₂ ⁺ radicals in Embodiment 2 of the present invention. FIG. 8 shows the process until the generation of N radicals or N ₂ ⁺ radicals and the arrival of these radicals at the SiO ₂ film 2 surface or the SiO ₂ film 2 / Si substrate 1 interface in the second embodiment of the present invention. FIG. Comparing Figure 11 and Figure 5 or Figure 13 and Figure 8, Ar ^* is the generation of N radicals by the collision of the N ₂ is caused similarly, the change to the ground state of N ₂ by collision of N ₂ ⁺ and Xe is As a result, it can be seen that the generation efficiency of N ₂ ⁺ radicals decreases. In this way, the threshold voltage is maintained while maintaining the production efficiency by reducing the arrival amount of N ₂ ⁺ nitriding the SiO ₂ / Si interface while maintaining the arrival amount of N radicals that nitride the SiO ₂ surface. Shift can be reduced.

<Embodiment 3>
FIG. 3 is a diagram showing a nitriding apparatus for SiO ₂ film according to Embodiment 3 of the present invention. In the processing chamber 5, the Si substrate 1 having the SiO ₂ film 2 formed on the surface is disposed on the sample stage 3. The sample stage 3 includes a heating mechanism 4 and can freely set the sample temperature. For example, it is kept at room temperature to about 500 ° C.

Above the processing chamber 5, the microwave generated by the microwave generator 13 is supplied to a radial line slot antenna (RLSA) 15 through a microwave waveguide 14. For example, a microwave of 2.45 to 8.3 GHz is irradiated at a power density of about 0.5 to ⁵ W / cm ² . A dielectric plate 16 is disposed under the RLSA 15. Under the RLSA 15, an ion removal plate 24 is disposed at a distance of about 2.5 cm or more. Ar gas is supplied to the space between the RLSA and the ion removal plate, and Ar plasma is generated by the microwave. For example, it is performed under a pressure of about 0.1 to 100 Pa. Ar ⁺ and Ar ^* are generated in the Ar plasma. However, the majority occupies ground state Ar that is neither ionized nor excited. In the case of a plasma generated using RLSA, a space of 2.5 cm or less immediately below RLSA is a region where plasma is generated (plasma generation region 19), and a space farther than that is generated Ar ⁺ , Ar ^*. Is a region where the plasma diffuses (plasma diffusion region 20).

As described above, the ion removal plate is a metal plate having a large number of holes, and a negative bias commensurate with taking in Ar ⁺ is applied. Since the processing chamber 5 is exhausted from below by the exhaust pump 6, Ar ⁺ , Ar ^* , and Ar in the ground state tend to flow downward through the ion removal plate. However, since the ion removal plate is negatively charged, Ar + is attracted to the ion removal plate, and is brought into contact with the ion removal plate to be supplied with electrons, thereby changing to Ar in the ground state. For this reason, Ar ⁺ cannot pass through the ion removal plate in the form of ions. Therefore, only Ar ^* and ground state Ar pass through the ion removal plate.

A rectifying plate 18 is disposed below the ion removal plate 17. N ₂ gas is supplied to the space between the ion removal plate and the rectifying plate, and collision between N _{2 in} the ground state and Ar ^* occurs. As a result, N, N ₂ ⁺ and N ₂ ^* are generated.

Since the processing chamber 5 is exhausted from below by the exhaust pump 6, N ₂ , N, N ₂ ⁺ and N ₂ ^* flow downward through the rectifying plate. Xe gas is supplied to the space below the rectifying plate, and these molecules collide with Xe in the ground state. When N ₂ ⁺ collides with Xe in the ground state, Xe is ionized and N ₂ changes to the ground state. Ar, N ₂ , and Xe are supplied at a flow rate ratio of about 90: 10: 5, for example. Note that, as in the first embodiment, the supplied rare gas is recovered by the rare gas recovery device 7, sent from the rare gas recovery port 12 to the purification device, and recycled.

FIG. 6 is a diagram showing a process of generating N radicals and N ₂ ⁺ radicals in Embodiment 3 of the present invention. FIG. 9 is a diagram showing the generation of N radicals or N ₂ ⁺ radicals and the process until these radicals reach the SiO ₂ film surface or the SiO ₂ / Si interface in the third embodiment of the present invention. Comparing Figure 11 and Figure 6 or Figure 13 and Figure 9, Ar ^* the generation of N radicals by collision of N ₂ takes place in the same manner but, Ar ⁺ and N ₂ or Ar ⁺ and N ₂ ^* in accordance N ₂ ⁺ a Since generation does not occur, it can be seen that the generation efficiency of N ₂ ⁺ radicals decreases. Furthermore, it can be seen that the generation efficiency of N ₂ ⁺ radicals is further reduced because the change of N _{2 to} the ground state due to collision of N ₂ ⁺ and Xe occurs. In this way, the threshold voltage is maintained while maintaining the production efficiency by drastically reducing the arrival amount of N ₂ ⁺ nitriding the SiO ₂ / Si interface while maintaining the arrival amount of N radicals that nitride the SiO ₂ surface. Shift can be reduced.

  As described above, the embodiments of the present invention have been described, but it is also planned from the beginning to appropriately combine the configurations of the above-described embodiments.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1 is a schematic diagram showing an outline of a nitriding apparatus for a SiO ₂ film according to Embodiment 1 of the present invention. Is a schematic view showing an outline of a nitriding apparatus of the SiO ₂ film according to the second embodiment of the present invention. Is a schematic view showing an outline of a nitriding apparatus of the SiO ₂ film according to the third embodiment of the present invention. In the first embodiment of the present invention and showing a process of generating N radicals and N ₂ ⁺ radical. In a second embodiment of the present invention and showing a process of generating N radicals and N ₂ ⁺ radical. In the third embodiment of the present invention and showing a process of generating N radicals and N ₂ ⁺ radical. In the first embodiment of the present invention and showing a process until reaching the N radical and N ₂ ⁺ product and the SiO ₂ film. In a second embodiment of the present invention and showing a process until reaching the N radical and N ₂ ⁺ product and the SiO ₂ film. In the third embodiment of the present invention and showing a process until reaching the N radical and N ₂ ⁺ product and the SiO ₂ film. It is a schematic diagram which shows the outline of the conventional radical nitriding apparatus. Is a diagram illustrating a process of generating N radicals and N ₂ ⁺ radicals in radical nitriding using a conventional Ar / N ₂ plasma. It is a diagram illustrating a process of generating N radicals and N ₂ ⁺ radicals in radical nitridation using Xe / N ₂ plasma disclosed in Patent Document 1. It is a diagram showing a process until reaching the conventional Ar / N ₂ radical N radicals in nitride and N ₂ ⁺ product and the SiO ₂ film. Is a diagram showing a process until reaching the N radical and N ₂ ⁺ product and the SiO ₂ film in the Xe / N ₂ radical nitriding shown in Patent Document 1.

Explanation of symbols

1 Si substrate, 2 SiO ₂ film, 3 sample stage, 4 heating mechanism, 5 processing chamber, 6 exhaust pump, 7 noble gas recovery device, 8, 9, 21 gas inlet, 10, 11, 22 gas, 12 noble gas Recovery port, 13 microwave generator, 14 waveguide, 15 RLSA, 16 dielectric plate, 17 ion removal plate, 18 rectifying plate, 19 plasma generation region, 20 plasma diffusion region.

Claims (6)

A semiconductor device manufacturing apparatus comprising at least a processing chamber, a radial line slot antenna, a first gas introduction port for introducing a first gas, and a second gas introduction port for introducing a second gas,
The processing chamber includes a negatively charged metal ion removal plate,
The first gas inlet and the second gas inlet are provided in the processing chamber, and are provided at positions where the first gas is mixed with the second gas after passing through the ion removal plate. Semiconductor device manufacturing equipment. The processing chamber further includes a rectifying plate made of an insulator and a third gas introduction port for introducing a third gas,
The third gas introduction port is provided at a position where the first gas and the second gas that have passed through the ion removal plate are mixed and passed through the rectifying plate and then mixed with the third gas. The manufacturing apparatus of the semiconductor device as described in 2. above. At least a processing chamber, a radial line slot antenna, a first gas introduction port for introducing a first gas, a second gas introduction port for introducing a second gas, and a third gas introduction port for introducing a third gas; A semiconductor device manufacturing apparatus comprising:
The processing chamber includes a rectifying plate made of an insulating material,
The first gas inlet, the second gas inlet, and the third gas inlet are provided in the processing chamber,
The apparatus for manufacturing a semiconductor device, wherein the third gas introduction port is provided at a position where a mixed gas of the first gas and the second gas is mixed with the third gas after passing through the rectifying plate. A method of manufacturing a semiconductor device for nitriding a SiO ₂ film on a Si substrate,
An Ar plasma generation step for generating a plasma containing at least Ar ions and metastable excited Ar molecules from Ar gas;
An Ar ion removal step of removing Ar ions from the plasma by passing the plasma through a negatively charged metal ion removal plate;
A radical generation step of causing N ₂ molecules to collide with Ar molecules in a metastable excited state contained in the plasma that has passed through the ion removal plate to generate N radicals;
And a nitriding step of nitriding the SiO ₂ film with the generated N radical in this order. After the radical generation step and before the nitridation step,
A rectifying step of passing the plasma through a rectifying plate;
The method of manufacturing a semiconductor device according to claim 4, further comprising a contact step of bringing Xe gas into contact with the plasma that has passed through the rectifying plate. A method of manufacturing a semiconductor device for nitriding a SiO ₂ film on a Si substrate,
An N plasma generation step of generating a plasma containing at least N radicals and N ₂ ⁺ radicals from a mixed gas of Ar gas and N ₂ gas;
A rectifying step of passing the generated plasma through a rectifying plate;
Contacting the Xe gas with the plasma that has passed through the rectifying plate;
A method of manufacturing a semiconductor device, comprising at least a nitriding step of nitriding the SiO ₂ film with the plasma comprising N radicals in this order.

Images