JPH09115852A - Device and method for introducing impurity - Google Patents

Abstract

PROBLEM TO BE SOLVED: To introduce a high-concentration impurity to a shallow position on the surface of a sample such as a silicon substrate and safely perform the impurity introducing operation. SOLUTION: A sample table 12 which holds a silicon substrate 11, which is a body to which an impurity is to be introduced, is provided at the bottom of a vacuum chamber 10. A high-frequency power source 14 is connected to the sample table 12 through a coupling capacitor 13, and the self-bias of the high-frequency power source 14 is, for example, 500V. At the bottom of the vacuum chamber 10, a gas introducing means 15 is provided for introducing sputtering gas such as argon gas. At the top of the vacuum chamber 10, a solid-stage target 16 which contains an impurity to be introduced, for example, boron, is arranged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an impurity introducing apparatus and an impurity introducing method for introducing impurities into a sample such as a silicon substrate.

[0002]

2. Description of the Related Art In recent years, with the reduction of design rules of semiconductor devices, it is necessary to reduce the junction depth of a diffusion layer of a transistor in order to prevent the short channel effect and increase the speed of the device. . Therefore, the MOS
For FET, for example, a device having a 0.1 μm rule requires a junction depth of 80 nm or less, and also for a bipolar transistor, the depth of a diffusion layer in a base region is 50 nm or less for speeding up. There is a demand for the above, and an impurity introduction technique for obtaining a shallower junction is being studied.

On the other hand, one of the conventional impurity introduction techniques
As an example, an ion implantation is performed in which a gas containing impurities to be introduced is supplied into a vacuum chamber, the supplied impurity gas is excited to be in an ion state, and the impurity ions are accelerated to be injected into the surface portion of a sample such as a silicon substrate. The law is known.

[0004]

However, a shallow junction (for example, 30 n) is formed by the above-described impurity introduction method of ionizing the impurity gas introduced into the chamber and accelerating the ionized impurities to implant them into the silicon substrate.
m or less), the acceleration energy of impurity ions must be reduced.

However, when the acceleration energy is reduced, the ion current is lowered and the implantation time is lengthened, resulting in poor throughput, and when the acceleration energy is further reduced, the ion current cannot be obtained and the ion implantation itself can be performed. There is a problem of disappearing.

Further, in the conventional ion implantation method, in order to implant impurity ions having a high energy of about several keV, Rp (projection range: average of impurity ions implanted at the time of ion implantation from the surface). (Depth) reaches the inside of a sample such as a silicon substrate, and there is a problem that a high impurity concentration of 1 × 10 ²⁰ (/ cm ³ ) or more on the surface portion of the silicon substrate cannot be obtained. .

Further, as a source gas for impurities used for ion implantation, a highly poisonous gas such as arsine, diborane, or phosphine is generally used, so that a considerably expensive facility is required to safely perform the impurity introduction work. Therefore, there is also a problem that the device cost becomes enormous. Examples of the expensive equipment include high-quality pipes and valves through which highly toxic gas flows, highly toxic gas sensors, and toxic gas treatment facilities.

In view of the above, it is an object of the present invention to allow a high concentration of impurities to be introduced into a shallow position on the surface portion of a sample such as a silicon substrate and to safely perform the impurity introduction work.

[0009]

In order to achieve the above-mentioned object, the present invention has a method in which a sputtering target gas is made to collide with a solid target containing impurities in a plasma state to cause impurities to jump out of the target, and the jumped impurities Is introduced into the surface of the sample.

Specifically, the solution means taken by the invention of claim 1 is directed to an impurity introduction device for introducing impurities into a sample such as a semiconductor substrate, and a vacuum chamber whose inside is kept in a vacuum state, and A sample table provided in a vacuum chamber for holding the sample, a solid target provided in the chamber and containing the impurities,
Gas introducing means for introducing a gas for sputtering into the chamber, and by exciting the gas introduced into the chamber to generate plasma composed of the gas, a gas in a plasma state is made to collide with the target. Plasma sputtering means for sputtering impurities contained in the target, and forming a self-bias between the plasma generated by the plasma generating means and the sample stage to remove impurities sputtered from the target by the sample stage. And a high-frequency power source to be introduced into the sample held in.

According to the first aspect of the present invention, when the gas introduced into the chamber and excited to be in a plasma state is made to collide with a target containing impurities, the impurities contained in the target are sputtered. When a self-bias is formed between the plasma and the sample stage by the high frequency power source, the impurities sputtered from the target are introduced into the surface portion of the sample held on the sample stage.

As described above, since the impurities are sputtered by colliding plasma with the solid target containing impurities, it is not necessary to use a highly toxic gas as in the ion implantation method, so that the impurity introduction work can be performed safely. it can.

Further, since a low voltage of about several tens of V to 2 kV is applied to the sample stage to introduce impurities with low energy, the impurities are intensively introduced to the surface portion of the sample.
A high concentration of impurities can be introduced into a shallow region on the surface of the sample.

Further, the impurities can be introduced even if the sample is held at a low temperature, for example, at a temperature of about 23 to 160 ° C., instead of holding the sample at a high temperature as in the ion implantation method.

According to a second aspect of the present invention, in the structure of the first aspect, the plasma generating means is provided outside the vacuum chamber, and means for introducing a plasma generating wave having a frequency of 1 GHz or more into the vacuum chamber. Is added.

According to a third aspect of the present invention, the structure of the second aspect further comprises magnetic field generating means for generating a magnetic field for increasing the density of the plasma generated in the vacuum chamber.

According to a fourth aspect of the present invention, the target has a configuration in which the target contains boron and nitrogen as the impurities.

By the way, the N-channel type transistor and the P
In a dual-gate CMOS transistor whose gate has a different conductivity type from that of a channel-type transistor, it is necessary to prevent the exudation of boron from the gate electrode to the substrate, which adversely affects the device characteristics. Therefore, it has been proposed to introduce nitrogen into the gate insulating film in order to prevent the exudation of boron from the gate electrode to the substrate. However, in order to introduce nitrogen into the gate insulating film by the ion implantation method, it is necessary to introduce nitrogen gas into the vacuum chamber and accelerate nitrogen ions to inject them into the gate electrode.
According to this method, a step of implanting nitrogen ions is required before or after the ion implantation step for forming the impurity layer forming the transistor.

On the other hand, according to the configuration of claim 4,
Since the target contains boron and nitrogen as impurities, when a gas in a plasma state is made to collide with the target, the boron and nitrogen contained in the target are sputtered, and the boron is deposited on the n-type semiconductor region and the gate electrode of the semiconductor substrate. Then, the p-type source / drain regions and the p-type gate electrode are formed, and nitrogen atoms are introduced into the gate insulating film.

According to a fifth aspect of the invention, in addition to the configurations of the first to third aspects, the target includes a configuration containing boron nitride.

According to a sixth aspect of the present invention, in addition to the configurations of the first to third aspects, the gas introduced by the gas introducing means includes an argon gas and a nitrogen gas.

According to a seventh aspect of the present invention, a solution means is intended for an impurity introduction device for introducing a first impurity and a second impurity into a sample such as a semiconductor substrate, and the inside is kept in a vacuum state. A first vacuum chamber and a first vacuum chamber for holding the sample, which is provided in the first vacuum chamber
And a solid first target provided in the first chamber and containing the first impurity,
First gas introducing means for introducing a gas for sputtering into the first chamber, and plasma by exciting the gas introduced into the first chamber to generate plasma of the gas. First plasma generating means for causing a gas in a state to collide with the first target to sputter the first impurities contained in the first target; plasma generated by the first plasma generating means; and the first plasma generating means. A first high-frequency power source for introducing the first impurity sputtered from the first target into the sample held on the first sample stage by forming a self-bias with the first sample stage. And a second vacuum chamber whose inside is held in a vacuum state, and a second sample which is provided in the second vacuum chamber and holds the sample. A pedestal, a solid second target provided in the second chamber and containing the second impurity, and a second gas introduction unit for introducing a sputtering gas into the second chamber. And exciting the gas introduced into the second chamber to generate plasma composed of the gas, thereby causing the gas in the plasma state to collide with the second target and to the second target. By forming a self-bias between the second plasma generating means for sputtering the contained second impurities and the plasma generated by the second plasma generating means and the second sample stage, Second high-frequency power source for introducing the second impurity sputtered from the target of No. 2 into the sample held on the second sample stage, and the inside is kept in a vacuum state. A transfer which is in communication with each of the first vacuum chamber and the second vacuum chamber via a shutter, and which has a transfer means for transferring the sample from the first sample stage to the second sample stage. And a room.

According to the structure of claim 7, similarly to the structure of claim 1, in each of the first vacuum chamber and the second vacuum chamber, the first or second sputtering target is sputtered from the first or second target. Impurities are introduced into the surface of the sample held on the sample table. In this case, since the impurities are sputtered by colliding plasma with a solid target containing impurities, it is not necessary to use a highly toxic gas as in the ion implantation method, so that the impurity introduction work can be performed safely and 10V-2
Since a low voltage of about kV can be applied to the sample stage to introduce impurities with low energy, it is possible to introduce high-concentration impurities into a shallow region on the surface of the sample. Also,
Since the impurities can be introduced while keeping the sample at a low temperature, it is possible to perform the impurity introduction process using a normal resist.

Further, the inside is held in a vacuum state and communicates with each of the first vacuum chamber and the second vacuum chamber via shutters, and the sample is moved from the first sample stage to the second sample stage. Since the transport chamber having the transport means for transporting above is provided, the sample into which the first impurity is introduced in the first vacuum chamber is loaded into the second vacuum chamber while being held in a vacuum state, and the second vacuum chamber is loaded. The second impurity can be introduced in the vacuum chamber.

The solution means taken by the invention of claim 8 is directed to an impurity introduction method for introducing impurities into a sample such as a semiconductor substrate, and a sample table provided in a vacuum chamber whose interior is held in a vacuum state. A holding step of holding the sample and a solid target containing the impurities in the vacuum chamber, a gas introduction step of introducing a sputtering gas into the chamber, and a gas introduction step introduced in the gas introduction step. And a plasma generating step of causing a gas in a plasma state to collide with the target to sputter impurities contained in the target by generating a plasma of the gas, and applying high-frequency power to the sample stage to generate the plasma. Forming a self-bias between the plasma generated in the generation step and the sample stage Ri, in which a structure in which the sputtered impurities from the target and an impurity introducing step of introducing the sample held on the sample stage.

According to the structure of claim 8, as in the structure of claim 1, in the vacuum chamber, the impurities sputtered from the target are introduced into the surface portion of the sample held on the sample table. In this case, since the impurities are sputtered by colliding plasma with a solid target containing impurities, it is not necessary to use a highly toxic gas as in the ion implantation method, so that the impurity introduction work can be performed safely and Since a low voltage of about 10 V to 2 kV can be applied to the sample stage to introduce impurities with low energy, it is possible to introduce high-concentration impurities into a shallow region on the surface of the sample. Moreover, since the impurities can be introduced while keeping the sample at a low temperature, the impurity introduction process can be performed using a normal resist.

According to a ninth aspect of the present invention, in the structure according to the eighth aspect, the plasma generating step is performed at a pressure of 1 GH in the vacuum chamber.
A configuration including a step of introducing a plasma generation wave having a frequency of z or higher to generate plasma of the gas is added.

The invention of claim 10 is based on the structure of claim 9.
The plasma generation step adds a configuration including a step of increasing the density of plasma generated in the vacuum chamber.

According to an eleventh aspect of the present invention, in addition to the constitutions of the eighth to tenth aspects, the impurities contained in the target are boron and nitrogen.

According to a twelfth aspect of the present invention, in addition to the constitutions of the eighth to tenth aspects, the target includes a constitution containing boron nitride.

According to a thirteenth aspect of the present invention, in addition to the constitutions of the eighth to tenth aspects, the gas introduced in the gas introducing step contains an argon gas and a nitrogen gas.

[0032]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an impurity introduction method and an apparatus therefor according to the present invention and a semiconductor device manufacturing method will be described with reference to the drawings.

(First Embodiment) FIG. 1 shows a first embodiment of the present invention.
2 shows a cross-sectional structure of the impurity introduction device according to the embodiment of the present invention, and as shown in FIG. 1, a vertical cylindrical vacuum chamber 1
Below 0, a sample table 12 for holding a sample such as a semiconductor wafer for LSI, which is a body to which impurities are introduced, for example, a silicon substrate 11 is provided. 800 kHz to 100 MHz on the sample table 12 via the coupling capacitor 13.
Is connected to a high frequency power source 14 for applying high frequency power of, for example, 13.56 MHz, and the self bias of the high frequency power source 14 is, for example, 500V. Further, a gas introducing means 15 for introducing a sputtering gas such as argon gas is provided at the bottom of the vacuum chamber 10. In addition to argon gas, helium gas, nitrogen gas, or the like can be used as the sputtering gas.

Further, around the outside of the vacuum chamber 10, for example, 3 to 4 plate-shaped permanent magnets 17 as magnetic field generating means for generating a magnetic field in the vacuum chamber 10 are arranged at appropriate intervals. In addition, the outside of the vacuum chamber 10 has, for example, 2.
ECR (Electron Cyclotro) as a means for generating plasma that introduces microwaves of 45 GHz
n Resonance) 18 extends from between the permanent magnets 17 and is connected to the vacuum chamber 10. As the magnetic field generating means, a solenoid coil may be provided instead of the plate-shaped permanent magnet 17. Further, as the plasma generating means, instead of the ECR 18,
ICP, helicon, magnetron, two-frequency, triode, LEP and the like can be used as appropriate, but an apparatus capable of introducing a plasma-generated wave having a frequency of 1 GHz or higher is preferable for the reason described later.

As a feature of the first embodiment, a solid target 16 containing an impurity (for example, boron) to be introduced is arranged above the vacuum chamber 10. The impurities contained in the target 16 include, in addition to boron, elements usually used for doping semiconductors such as arsenic, phosphorus, indium, antimony, nitrogen, aluminum and silicon.

A method of introducing impurities into the silicon substrate 11 using the impurity introducing apparatus according to the first embodiment will be described below.

First, when a gas for sputtering (eg, argon) is introduced into the vacuum chamber 10 from the gas introducing means 15 and a microwave is introduced from the ECR 18 into the vacuum chamber 10, the sputtering gas introduced into the vacuum chamber 10 is introduced. The gas is ionized by microwaves and becomes a plasma state. The argon atoms in the plasma state are accelerated by the plasma potential formed in the vacuum chamber 10 and collide with the surface of the target 16 containing impurities.
Impurities are blown off from 6. The impurities blown off from the target 16 are transferred from the argon atoms toward the sample stage 12 by the self-bias generated between the sample stage 12 and the argon atoms in the plasma state by the high frequency power applied to the sample stage 12. And the silicon substrate 11 provided so as to face the target 16.
It is driven into the surface part of.

By the way, in the conventional sputtering apparatus, since the material forming the target is metal,
Plasma is also generated by a parallel plate type plasma generator which does not have plasma generating means such as ECR. However,
When the target 16 containing boron is used as in the first embodiment, since boron has a high insulating property, the generated electric field is diverged, so that plasma is difficult to generate. Therefore, in the first embodiment, the ECR18
Is installed in the vacuum chamber 1 for microwaves of 1 GHz or more.
Introduce into 0. When a microwave of 1 GHz or more is introduced into the vacuum chamber 10 as described above, plasma having a high density of about 1000 times that of the parallel plate type plasma generator is generated. Therefore, impurities such as boron are removed in a short time from the silicon substrate 1.
It can be driven into the surface of 1. Therefore, since the temperature of the silicon substrate 11 does not rise to 300 ° C. or higher, it is possible to avoid the situation where the resist pattern formed on the silicon substrate 11 burns.

Although it is considered that the frequency of the high frequency power applied to the sample stage 12 is 1 GHz or higher, the effect of the self-bias generated between the sample stage 12 and the plasma is reduced by doing so. Therefore, it becomes difficult for impurities to be implanted into the surface portion of the silicon substrate 11, and 1 GHz
Since it is difficult to provide the electromagnetic wave shielding means for shielding the above microwaves in the vacuum chamber 10, there is a safety problem.

Further, in the first embodiment, since the permanent magnet 18 for generating the magnetic field is provided in the vacuum chamber 10, the microwave introduced by the ECR 18 and the magnetic field generated by the permanent magnet 18 work together. By the action
The ionization efficiency of argon gas is improved. For this reason, impurities such as boron can be implanted into the surface portion of the silicon substrate 11 in a shorter time, so that the temperature rise of the silicon substrate 11 can be further suppressed.

FIG. 2 shows SIMS profiles of a silicon substrate into which impurities have been introduced by the impurity introduction method according to the first embodiment and a silicon substrate into which impurities have been introduced by a conventional ion implantation apparatus.

As is apparent from FIG. 2, according to the impurity introduction method of the first embodiment, the concentration of the impurities introduced into the surface portion of the silicon substrate is 1 × 10 ²¹ (/ cm ³ ), and The junction depth at which the concentration becomes 1 × 10 ¹⁸ (/ cm ³ ) is 18 nm. On the other hand, according to the conventional ion implantation method (accelerating voltage 2 KeV), the concentration of impurities introduced into the surface portion of the silicon substrate is 3 × 10 ²⁰ (/ cm 2).
³ ) and the impurity concentration is 1 × 10 ¹⁸ (/ cm ³ ).
The junction depth is 32 nm.

As described above, as compared with the conventional ion implantation method in which the gas containing the impurity element introduced into the silicon substrate is supplied into the vacuum chamber and the impurity gas is excited to introduce into the silicon substrate. According to the method in which the solid target 16 contains impurities to be introduced into the silicon substrate 11 and the silicon substrate 16 is doped with impurities as in the first embodiment, the potential difference between the plasma and the silicon substrate 11 (several 10V
Plasma doping is performed with low energy of about 2 kV), and impurities are introduced into the surface portion of the silicon substrate 11. In this way, impurities can be introduced with extremely low energy as compared with the potential difference (usually about 30 kV) used in the conventional ion implantation method, so that a shallow and high-concentration impurity layer is formed on the surface of the silicon substrate 11 near the surface. The impurity concentration can be increased. Therefore, for devices with small design rules,
A transistor element having a small short channel effect and a large driving force can be easily obtained.

Further, according to the first embodiment, the target 16 made of solid is used as the impurity to be doped in the silicon substrate 11, and the gaseous impurities are not handled unlike the conventional case, so that it is extremely safe. At the same time, the impurity introduction device can be simplified.

Hereinafter, a method for manufacturing a semiconductor device using the impurity introducing apparatus according to the first embodiment will be described with reference to FIG.
This will be described with reference to FIG.

First, as shown in FIG. 5A, an element isolation region 101 is formed on an n-type semiconductor substrate 100. After that, the degree of vacuum of the semiconductor substrate 100 is several meters to several tens of meters.
Substrate temperature 3 in vacuum chamber 10 kept at r
While maintaining the temperature below 00 ° C., while introducing argon gas from the gas introducing means 15, from the ECR 18 to 1 GHz
A microwave having the above frequency is introduced, and high frequency power is applied to the sample stage 12 from the high frequency power supply 14. In this way, the target 1 containing argon, for example, boron, which has become a plasma state in the vacuum chamber 10
Impurity atoms are emitted from the target 16 by colliding with 6 at a self-bias of 5 keV or less for about several seconds to 10 minutes. Impurity atoms, such as boron, emitted from the target 16 are introduced into the surface portion of the semiconductor substrate 100.

Next, the semiconductor substrate 100 is subjected to heat treatment to diffuse the impurities so that the surface concentration of the semiconductor substrate 100 is 1 × 10 5 as shown in FIG. 5B.
A high-concentration diffusion layer 102 having a diffusion layer depth of ²⁰ (/ cm ³ ) or more and a diffusion layer depth of 100 nm or less is formed.

Next, after depositing an interlayer insulating film 103 over the entire surface of the semiconductor substrate 100, the interlayer insulating film 103 is subjected to photolithography and etching, as shown in FIG. 5C. A contact hole 104 is formed in the interlayer insulating film 103.

Next, as shown in FIG. 5D, the electrode 10 is formed on the interlayer insulating film 103 including the contact hole 104.
By forming 5, a diode is obtained.

Although illustration and detailed description are omitted, an n-channel type or p-channel type MOS transistor can be manufactured by using the impurity introduction device according to the first embodiment.

(Second Embodiment) FIG. 3 shows a second embodiment of the present invention.
4 shows a planar structure of the impurity introducing apparatus according to the embodiment of the present invention, and as shown in FIG. 3, the transfer chamber 23 in which the first vacuum chamber 21 and the second vacuum chamber 22 are kept in vacuum.
A first shutter 24 is provided between the first vacuum chamber 21 and the transfer chamber 23.
A second space is provided between the second vacuum chamber 22 and the transfer chamber 23.
Shutter 25 is provided. In addition, the transfer chamber 23
Is provided with a third shutter 26 for loading and unloading the sample.

In the first vacuum chamber 21, as in the first embodiment, the first sample table 29 holding the solid first target 27 containing p-type impurities such as boron and the semiconductor substrate 28 is held. Is provided on the first sample table 29 via the first coupling capacitor 30 and, for example, 8
A first high frequency power supply 31 for applying high frequency power having a frequency of 00 kHz to 100 MHz is connected. Further, in the first vacuum chamber 21, a first microwave generator 32 for introducing a plasma generation wave and a first gas supply device 3 for introducing a sputtering gas such as argon.
3 are provided.

In the second vacuum chamber 22 as well, the second sample stage 3 holding the solid second target 35 and the semiconductor substrate 36 containing the n-type impurity such as arsenic or phosphorus is held.
7 is provided, and for example, 800 kHz to 100 on the second sample stage 37 via the second coupling capacitor 38.
A second high frequency power supply 39 for applying high frequency power having a frequency of MHz is connected. In addition, the second vacuum chamber 22 is provided with a second microwave generator 41 that introduces a plasma-generated wave and a second gas supply device 42 that introduces a sputtering gas such as argon.

The transfer chamber 23 is provided with a transfer device 45 having an arm 45a. The transfer device 45 transfers the semiconductor substrates 28 and 36 into and out of the first chamber 21, and the second chamber 22. It is carried in or out. As a result, the semiconductor substrate in which the p-type impurity is introduced in the first chamber 21 is carried into the second chamber 22 in a vacuum state, and the second chamber 2
An n-type impurity can be introduced within 2.
Since the method of introducing impurities into the semiconductor substrate using the impurity introducing apparatus according to the second embodiment is the same as that of the first embodiment, its explanation is omitted.

A method of manufacturing a semiconductor device using the impurity introducing device according to the second embodiment will be described below with reference to FIG.
This will be described with reference to FIG.

First, as shown in FIG. 6A, a p-type semiconductor region 20 which is an n-channel MOS transistor forming region is formed on a p-type semiconductor substrate 200 made of silicon.
1, p-channel type MOS transistor formation region n
A type semiconductor region 202 and an element isolation layer 203 for separating the p-type semiconductor region 201 and the n-type semiconductor region 202 are formed. After that, a thickness of 4 is formed on the p-type semiconductor region 201.
A first gate insulating film 204 made of a silicon oxide film having a thickness of 10 nm and a first gate electrode 205A made of a polysilicon film having a thickness of 100 nm to 300 nm are sequentially formed, and a thickness is formed on the n-type semiconductor region 202. 4-10n
second gate insulating film 206 made of a silicon oxide film of m
Then, a second gate electrode 207A made of a polysilicon film having a thickness of 100 to 300 nm is sequentially formed.

Next, after depositing a silicon oxide film having a thickness of 100 to 200 nm over the entire surface of the semiconductor substrate 200 by the CVD method, the silicon oxide film is anisotropically etched to form silicon oxide. By etching back the film, as shown in FIG. 6B, the first and second films are formed.
Sidewalls 208 are formed on the side surfaces of the gate electrodes 205A and 207A.

Next, after the semiconductor substrate 200 is loaded into the second vacuum chamber 22, the second vacuum chamber 22 is loaded.
With the inside kept at a degree of vacuum of several m to several tens of mtorr and the temperature of the semiconductor substrate 200 kept at 160 ° C. or lower, plasma argon is applied to the second target 35 containing n-type impurities such as As (arsenic). Collide with a self-bias of 5 keV or less for about several seconds to 10 minutes. In this way, n sputtered from the second target 35
A type impurity such as As is used as the p-type semiconductor region 201 and the first gate electrode 20 by using the sidewall 208 as a mask.
5A, as shown in FIG. 6B, n-type source / drain regions 209 are formed in the p-type semiconductor region 201, and the resistance of the first gate electrode 205A is reduced. It changes to the gate electrode 205B,
An n-type MOS transistor is formed. Then, after the semiconductor substrate 200 is transferred from the second vacuum chamber 22 to the first vacuum chamber 21 by the transfer means 45, the inside of the first vacuum chamber 21 is maintained at a vacuum degree of several m to several tens mtorr and the semiconductor With the temperature of the substrate 200 kept at 160 ° C. or lower, argon in the plasma state is applied to the first target 27 containing p-type impurities such as B (boron).
Collide for several seconds to 10 minutes with a self-bias of keV or less. By doing so, the p-type impurity, for example, B, sputtered from the first target 27 is used as the n-type semiconductor region 202 and the second target region by using the sidewall 208 as a mask.
Of the n-type semiconductor region 2 by being introduced into the gate electrode 207A of
02, a p-type source / drain region 210 is formed, and the second gate electrode 207A has a low resistance p.
Type gate electrode 207B, which results in a p-type MO
An S transistor is formed.

Next, for the semiconductor substrate 200, 900
The impurity ions introduced into the n-type and p-type source / drain regions 209 and 210 are activated by performing heat treatment at a temperature of 1050 ° C. for about 1 to 60 seconds. As a result, the surface impurity concentration of the n-type and p-type source / drain regions 209 and 210 is 1 × 10.
A high-concentration impurity diffusion layer with a diffusion layer depth of ²⁰ (/ cm ³ ) or more and a diffusion layer depth of 100 nm or less is obtained. After that, although not shown, by forming some metal wiring layers on the semiconductor substrate 200 via an interlayer insulating film, a semiconductor device having a CMOS transistor is obtained.

(Third Embodiment) FIG. 4 shows a third embodiment of the present invention.
4 shows a cross-sectional structure of the impurity introducing device according to the embodiment of the present invention. As shown in FIG. 4, a sample table 52 for holding, for example, a silicon substrate 51 is provided in the vacuum chamber 50, and the sample table 52 is provided. Is a coupling capacitor 53
A high frequency power source 54 for applying high frequency power having a frequency of 800 kHz to 100 MHz is connected via
The self-bias of the high frequency power supply 54 is, for example, 500V. Further, in the vacuum chamber 50, a solid target 55 containing impurities (for example, boron) to be introduced.
Is arranged.

As a feature of the third embodiment, a first gas introducing means 56 for introducing a sputtering gas such as argon and a second gas introducing means for introducing an inert gas such as nitrogen into the vacuum chamber 50. The gas introduction means 57 is provided.

Although not shown, generation of plasma for supplying plasma generation waves such as ECR, ICP, helicon, magnetron, dual frequency, triode or LEP to the impurity introduction device according to the third embodiment. By providing the means, high-density plasma can be generated for the same reason as in the first embodiment.

Hereinafter, a method of introducing impurities into the silicon substrate 51, which is performed using the impurity introducing apparatus according to the third embodiment, will be described.

First, the argon gas is introduced into the vacuum chamber 50 from the first gas introducing means 56 and the second gas is introduced into the vacuum chamber 50.
When the nitrogen gas is introduced from the gas introduction means 57, the argon gas and the nitrogen gas are ionized by the high frequency power applied by the high frequency power source 54 to be in the plasma state.
The argon atoms and nitrogen atoms in the plasma state are accelerated in the vacuum chamber 50 by the plasma potential and collide with the target 55, and impurities such as boron are repelled from the target 55. The impurities and the nitrogen atoms in the plasma state, which are repelled from the target 55, are introduced into the surface portion of the silicon substrate 51 by the self-bias between the plasma and the silicon substrate 51.

When the impurity introducing method according to the third embodiment is applied to the step of forming a p-type MOS transistor in the method of manufacturing a semiconductor device as described with reference to FIG. 6, the boron blown off from the target 55 is removed. The nitrogen atoms are introduced into the second insulating film 206 while being introduced into the n-type semiconductor region 202 and the second gate electrode 207A to form the p-type source / drain region 210 and the p-type gate electrode 207B. Therefore, the second insulating film 20
The nitrogen atoms introduced into 6 prevent boron introduced into the p-type gate electrode 207B from seeping out into the channel region of the n-type semiconductor region 202 in the heat treatment process performed later, and thus the characteristics of the p-type MOS transistor are reduced. Is improved. FIG. 7 shows the relationship between the gate voltage and the drain current when the nitrogen atom is not introduced and when it is introduced. As can be seen from FIG. 7, when the nitrogen atom is introduced, the drain current increases and the transistor The characteristics are improved.

Instead of providing the first gas introducing means 56 for introducing the argon gas and the second gas introducing means 57 for introducing the nitrogen gas in the vacuum chamber 50, the target 55 is introduced into the semiconductor substrate 51. The effect similar to that of the third embodiment can be obtained by using a material containing nitrogen in addition to the impurities described above or a material containing boron nitride.

[0067]

According to the impurity introducing apparatus of the first aspect of the present invention, since the impurities can be introduced without using a deadly poisonous gas as in the ion implantation method, the impurity introducing work can be carried out safely. This eliminates the need for expensive equipment such as high-quality pipes and valves, highly toxic gas sensors, and toxic gas processing equipment, which enables downsizing of the device and cost reduction of the device.

Further, a high concentration of impurities can be introduced into the shallow region on the surface of the sample, and the junction depth is 30 n.
Since an extremely shallow junction of m or less can be realized, the short channel effect can be prevented and the device can be speeded up in the MOSFET having a small design rule, and in the bipolar transistor, the diffusion layer of the base region can be formed. Since the depth can be reduced, the speed of the device can be increased.

Further, the sample is subjected to a low temperature, for example, 23 to 160 ° C.
Since the impurities can be introduced even if the temperature is maintained at about a certain temperature, the impurity introduction process can be performed using an ordinary resist.

According to the impurity introducing apparatus of the second aspect of the present invention, since the plasma introducing means is provided outside the vacuum chamber and introduces the plasma generating wave having a frequency of 1 GHz or more into the vacuum chamber, the vacuum is generated. Since high-density plasma can be generated in the chamber, impurities having a predetermined concentration can be introduced into the surface portion of the semiconductor substrate in a short time. For this reason, it is possible to prevent the temperature of the semiconductor substrate from rising to a temperature at which the resist pattern is burnt, so that the impurities can be surely introduced into a predetermined region of the semiconductor substrate.

According to the impurity introducing apparatus of the third aspect of the present invention, since it is provided with the magnetic field generating means for generating the magnetic field for increasing the density of the plasma generated in the vacuum chamber,
Since the ionization efficiency of the introduced gas is improved and the plasma density is further increased by the synergistic action with the plasma generation means for introducing the plasma generation wave having the frequency of 1 GHz or more into the vacuum chamber, the time is further shortened. Impurities having a predetermined concentration can be introduced into the surface portion of the semiconductor substrate.

According to the impurity introduction device of the fourth aspect of the present invention, since the target contains boron and nitrogen as impurities, boron is introduced into the n-type semiconductor region and the gate electrode of the semiconductor substrate, and the p-type source is introduced. A nitrogen atom is introduced into the gate insulating film while the drain region and the p-type gate electrode are formed, and the nitrogen atom introduced into the gate insulating film is boron introduced into the p-type gate electrode in a heat treatment process performed later. Are prevented from seeping into the channel region of the n-type semiconductor region, so that the characteristics of the p-type MOS transistor are improved.

According to the impurity introducing apparatus of the fifth aspect of the present invention, since the target contains boron nitride, when a plasma-like gas is made to collide with the target, boron atoms and nitrogen atoms are sputtered from the target. As in the third aspect of the invention, it is possible to prevent nitrogen atoms introduced into the gate insulating film from exuding boron introduced into the p-type gate electrode into the channel region of the n-type semiconductor region.

According to the impurity introducing apparatus of the sixth aspect of the invention, since the gas introduced by the gas introducing means contains the argon gas and the nitrogen gas, the nitrogen atom is included in the gate insulating film as in the invention of the fourth aspect. Is introduced to prevent the boron introduced into the p-type gate electrode from seeping out to the channel region of the n-type semiconductor region.

According to the impurity introducing apparatus of the seventh aspect of the present invention, the impurity introducing operation can be performed safely and the high concentration impurity is introduced into the shallow region of the surface portion of the sample, like the first aspect of the invention. In addition, the impurity introduction process can be performed using a normal resist.

Further, the sample into which the first impurity has been introduced in the first vacuum chamber can be carried into the second vacuum chamber while being kept in a vacuum state, and the second impurity can be introduced in the second vacuum chamber. , For example CMO
It becomes possible to easily manufacture a semiconductor device such as an S-transistor in which it is necessary to introduce two kinds of impurities without deteriorating the characteristics.

According to the impurity introducing method of the eighth aspect of the present invention, like the first aspect of the invention, the impurity can be introduced without using a highly poisonous gas as in the ion implantation method. Therefore, the impurity introducing work can be performed safely. In addition, it is possible to prevent a short channel effect in a MOSFET having a small design rule, to speed up the device, and to speed up the bipolar transistor. 23
Since the impurities can be introduced even if the temperature is maintained at about 160 ° C., the impurity introduction process can be performed using a normal resist.

According to the impurity introducing method of the ninth aspect of the present invention, the plasma generating step is performed in the vacuum chamber at 1 GH.
Since the method includes the step of introducing a plasma generation wave having a frequency of z or more to generate plasma composed of the gas, high density plasma can be generated in the vacuum chamber as in the invention of claim 2. Impurities having a predetermined concentration can be introduced into the surface portion of the semiconductor substrate in a short time.

According to the impurity introducing method of the tenth aspect of the invention, the plasma generating step includes the step of increasing the density of the plasma generated in the vacuum chamber by the magnetic field. Since the gas ionization efficiency is improved and the plasma density is further increased, it is possible to introduce impurities of a predetermined concentration into the surface portion of the semiconductor substrate in a shorter time.

According to the impurity introducing method of the eleventh aspect of the present invention, since the impurities contained in the target are boron and nitrogen, the nitrogen atoms introduced into the gate insulating film are later removed as in the fourth aspect of the invention. The boron introduced into the p-type gate electrode in the heat treatment step is prevented from seeping out to the channel region of the n-type semiconductor region.
The characteristics of the OS transistor are improved.

According to the impurity introducing method of the twelfth aspect of the invention, the target contains boron nitride,
As in the fifth aspect of the invention, it is possible to prevent nitrogen atoms introduced into the gate insulating film from exuding boron introduced into the p-type gate electrode into the channel region of the n-type semiconductor region.

According to the impurity introducing method of the thirteenth aspect, since the gas introduced in the gas introducing step contains the argon gas and the nitrogen gas, the nitrogen atom is introduced into the gate insulating film as in the sixth aspect. Thus, the boron introduced into the p-type gate electrode can be prevented from seeping out to the channel region of the n-type semiconductor region.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an impurity introduction device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing an impurity profile in a depth direction of a sample when impurities are introduced using the impurity introducing apparatus according to the first embodiment and a conventional ion implantation apparatus.

FIG. 3 is a plan view of an impurity introduction device according to a second embodiment of the present invention.

FIG. 4 is a sectional view of an impurity introducing device according to a third embodiment of the present invention.

5A to 5D are cross-sectional views showing respective steps of a method for manufacturing a semiconductor device using the impurity introducing apparatus according to the first embodiment.

6A to 6C are cross-sectional views showing respective steps of a method for manufacturing a semiconductor device using the impurity introducing apparatus according to the second embodiment.

FIG. 7 is a diagram showing a relationship between a gate voltage and a drain current when a nitrogen atom is not introduced into a gate insulating film of a MOSFET and when it is introduced.

[Explanation of symbols]

 10 Vacuum Chamber 11 Silicon Substrate 12 Sample Stage 13 Coupling Capacitor 14 High Frequency Power Supply 15 Gas Injecting Means 16 Target 17 Permanent Magnet 18 ECR 21 First Vacuum Chamber 22 Second Vacuum Chamber 23 Transfer Chamber 24 First Shutter 25 Second Shutter 26 third shutter 27 first target 28 semiconductor substrate 29 first sample stage 30 first coupling capacitor 31 first high-frequency power supply 32 first microwave generator 33 first gas supply device 35 Second target 36 Semiconductor substrate 37 Second sample stage 38 Second coupling capacitor 39 Second high frequency power supply 41 Second microwave generator 42 Second gas supply device 45 Transfer device 45a Arm 100 Semiconductor substrate 101 Element isolation region 102 High-concentration diffusion layer 103 Interlayer insulating film 104 Contact hole 105 Electrode 200 Semiconductor substrate 201 p-type semiconductor region 202 n-type semiconductor region 203 Element isolation layer 204 First gate insulating film 205A First gate electrode 205B N-type gate electrode 206th Second gate insulating film 207A Second gate electrode 207B P-type gate electrode 208 Side wall 209 n-type source / drain region 210 p-type source / drain region

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ichiro Nakayama 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (13)

[Claims] 1. An impurity introduction device for introducing impurities into a sample such as a semiconductor substrate, wherein a vacuum chamber whose inside is kept in a vacuum state, and an inside of the vacuum chamber which holds the sample A sample stage, a solid target provided in the chamber and containing the impurities, a gas introducing means for introducing a gas for sputtering into the chamber, and exciting the gas introduced into the chamber. Plasma generated by the gas and causing the gas in the plasma state to collide with the target to sputter impurities contained in the target, plasma generated by the plasma generating means, and the sample stage. Is sputtered from the target by forming a self-bias between And a high frequency power source for introducing impurities into the surface of the sample held on the sample stage. 2. The plasma generating means is provided outside the vacuum chamber, and 1 G is provided inside the vacuum chamber.
The impurity introduction device according to claim 1, which is a means for introducing a plasma-generated wave having a frequency of not less than Hz. 3. The impurity introduction device according to claim 2, further comprising magnetic field generation means for generating a magnetic field for increasing the density of the plasma generated in the vacuum chamber. 4. The target according to claim 1, wherein the target contains boron and nitrogen as the impurities.
4. The impurity introduction device according to any one of 3 above. 5. The impurity introducing apparatus according to claim 1, wherein the target contains boron nitride. 6. The impurity introduction device according to claim 1, wherein the gas introduced by the gas introduction unit contains an argon gas and a nitrogen gas. 7. An impurity introduction apparatus for introducing a first impurity and a second impurity into a sample such as a semiconductor substrate, the first vacuum chamber having an internal vacuum state, and the first vacuum chamber. A first sample table provided in the vacuum chamber for holding the sample; a solid first target provided in the first chamber and containing the first impurity; A first gas introduction means for introducing a sputtering gas into the first chamber; and a plasma formed of the gas by exciting the gas introduced into the first chamber to generate a plasma of the gas. A first plasma generating unit configured to cause a gas to collide with the first target to sputter a first impurity contained in the first target; and the first plasma generating unit. By introducing a self-bias between the generated plasma and the first sample stage, the first impurities sputtered from the first target are introduced into the sample held on the first sample stage. A first high-frequency power supply, a second vacuum chamber whose inside is held in a vacuum state, a second sample table which is provided in the second vacuum chamber and holds the sample, and the second A solid second target provided in the chamber of the second impurity and containing a second impurity; a second gas introduction unit for introducing a sputtering gas into the second chamber; Exciting the gas introduced into the chamber to generate plasma of the gas causes the gas in the plasma state to collide with the second target to cause the second target. By forming a self-bias between the second plasma generating means for sputtering the contained second impurities and the plasma generated by the second plasma generating means and the second sample stage, Second high frequency power source for introducing the second impurity sputtered from the target of the second sample into the sample held on the second sample stage, the inside of which is kept in a vacuum state, And a transfer chamber that is in communication with each of the vacuum chambers via a shutter and that has a transfer unit that transfers the sample from the first sample stage to the second sample stage. Impurity introduction device. 8. An impurity introduction method for introducing impurities into a sample such as a semiconductor substrate, wherein the sample is held on a sample table provided in a vacuum chamber whose inside is held in a vacuum state, and the vacuum chamber is used. A holding step of holding a solid target containing the impurities therein, a gas introducing step of introducing a sputtering gas into the chamber, and generating a plasma of the gas introduced in the gas introducing step. A plasma generating step in which a gas in a plasma state is made to collide with the target to sputter impurities contained in the target; and a high frequency power is applied to the sample stage to generate the plasma and the sample stage in the plasma generating step. Sputtering from the target by forming a self-bias between Impurity introduction method characterized in that comprises an impurity introduction step of introducing the ring impurities in samples held by the sample stage. 9. The plasma generating step according to claim 8, further comprising the step of introducing a plasma generating wave having a frequency of 1 GHz or higher into the vacuum chamber to generate plasma of the gas. Method for introducing impurities. 10. The method of introducing impurities according to claim 9, wherein the plasma generating step includes a step of increasing the density of plasma generated in the vacuum chamber. 11. The impurity introducing method according to claim 8, wherein the impurities contained in the target are boron and nitrogen. 12. The impurity introducing method according to claim 8, wherein the target contains boron nitride. 13. The method of introducing impurities according to claim 8, wherein the gas introduced in the gas introducing step includes an argon gas and a nitrogen gas.