WO2004109785A1

WO2004109785A1 - Impurity doping method, impurity doping apparatus and semiconductor device produced by using same

Info

Publication number: WO2004109785A1
Application number: PCT/JP2004/008281
Authority: WO
Inventors: Bunji Mizuno; Yuichiro Sasaki; Ichiro Nakayama; Hisataka Kanada
Original assignee: Matsushita Electric Industrial Co., Ltd.
Priority date: 2003-06-09
Filing date: 2004-06-08
Publication date: 2004-12-16
Also published as: TW200504785A; JP2005005328A; CN1806314A

Abstract

An impurity doping method and an impurity doping apparatus are disclosed which enable high-precision control in doping of a substrate with impurities. A substrate to be processed (5) is mounted on a holding stage (4) and rotated about a rotational driving axis (13). After activating a vacuum pump (6), gas evacuation by the vacuum pump (6) is stopped and a certain amount of a substance for plasma generation (a gas substance) in a measuring chamber (7) is introduced into a vacuum chamber (1) through a nozzle (14). The nozzle (14) is provided with many micronozzles (19), and a gas flow (15) is generated through these micronozzles (19) in the vacuum chamber (1) according to the excitation intensity of a plasma. The gas flow (15) is spatially non-uniform within the vacuum chamber (1). A plasma generating unit (2) is then driven by a power supply (3) so that the gas substance non-uniformly introduced in the vacuum chamber (1) is excited into a plasma, and the surface of the substrate to be processed (5) is exposed to the plasma for a certain time.

Description

Impurity introduction method, impurity introduction device, and semiconductor device formed using the same <Technical field>

The present invention relates to an impurity introduction method, an impurity introduction device, and a semiconductor device formed using the same, and more particularly to control of an impurity introduction profile in plasma doping.

Akira <Background technology>

In recent years, with the miniaturization of semiconductor devices, a technology for forming a shallow write junction has been required. In conventional semiconductor manufacturing technology, low-energy ion implantation of impurities of various conductivity types, such as boron (B), phosphorus (P), and arsenic (As), on a semiconductor substrate surface is widely used. .

A shallow junction of a semiconductor device is formed by using this ion implantation method, and although a shallow junction can be formed, there is a limit to the depth that can be formed by ion implantation. For example, it is difficult to introduce boron impurities at a shallow depth, and in ion implantation, the depth of the implantation region has been limited to about 100 nm from the substrate surface.

Therefore, in recent years, various doping methods have been proposed as a technique for enabling a shallower junction, and among them, the plasma doping technique has been attracting attention as being suitable for practical use. The plasma doping is a technique in which a reaction gas containing an impurity to be introduced is plasma-excited, and the substrate surface is irradiated with plasma to introduce the impurity. According to this technique, a shallow junction with a depth of 70 nm can be formed even with boron impurities (for example, see Non-Patent Documents 1 and 2).

(Non-Patent Document 1) Plasma doping technology: Bunji Mizuno (Vol. 70, No. 12, p. 1458—1462 (2001)

(Non-Patent Document 2) Sub-doped by low bias plasma doping Performance of 1 micron p MO SFET: Reliable and enhanced performances of sub-0. I μ ϊίΐ pMOSFETs doped by low biased Plasma Doping _N Damien Lenoble, etc. 0 0 years. At present, the miniaturization of semiconductor devices is progressing rapidly, and the design dimensions for mass production are approaching 100 nm or less. On the other hand, silicon wafers (semiconductor substrates) are increasing in diameter from 200 Omm φ to 300 mm φ. Under these circumstances, a high-precision control technique is required as described below in introducing impurities into the surface of a semiconductor substrate. .

The first is a technique for stably controlling the formation of a shallow junction where the depth near the substrate surface where impurities are introduced is 100 nm or less. The second is a technique for controlling the uniformity of the impurity distribution in the surface of the substrate having a large diameter as described above.

However, with the above-described ion implantation method, it is difficult to reduce the acceleration energy of B ions or BF ₂ ions to a low energy of several keV, particularly in the case of introducing boron impurities. There is a problem that it is difficult to form a shallow junction of 100 nm or less. On the other hand, in the conventional plasma doping method, it is easy to reduce the energy of plasma ions to 100 eV or less, and it is difficult to control a shallow junction having a depth of 50 nm or less as described above. Possible force There is a problem that it is not enough to control the uniformity of the impurity distribution in the surface of the substrate having a large diameter.

In addition, customization of semiconductor device products is progressing, and it is essential to respond to high-mix low-volume production. Here, in order to improve the production efficiency of a wide variety of products, a technology that can freely control the amount of impurities to be introduced in the surface of the semiconductor substrate when introducing impurities to the surface of the semiconductor substrate becomes very effective.

However, it is difficult to freely control the amount of impurities introduced in the above-described large-diameter substrate surface by any of the above-described ion implantation and the conventional plasma doping method. The above-mentioned problem in the impurity introduction is not limited to the semiconductor substrate forming the semiconductor device, but also applies to a matrix substrate serving as a liquid crystal display substrate forming a liquid crystal display device. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an impurity introduction method and an impurity introduction device capable of controlling the introduction of impurities into a substrate with high accuracy.

It is another object of the present invention to control the amount of impurities to be introduced and to achieve the introduction of impurities at an extremely shallow depth with high accuracy.

Another object of the present invention is to reduce the variation in impurity introduction depth or concentration depending on the position, and to introduce impurities to a uniform depth on a large-area substrate.

The impurity introduction method of the present invention is an impurity introduction method for exciting a substance containing an impurity by plasma and introducing the excited impurity into a substrate, wherein at least a part of the distribution of the plasma can be offset. Thus, the distribution of the substance in the vicinity of the surface of the base is adjusted. That is, the distribution of the substance in the vicinity of the surface of the substrate is adjusted according to the distribution of the plasma.

That is, the distribution of the plasma itself, that is, the distribution of the resulting plasma (the distribution of ions, radicals, neutral particles, etc.) is adjusted in accordance with the distribution of the plasma itself in such a manner as to cancel out the distribution. In practice, a simulation is performed or the material distribution near the substrate surface is adjusted based on the actual impurity introduction results. To cancel at least part of the plasma distribution means to give a material distribution that changes the original plasma distribution, and to generate a material distribution that does not depend on the original plasma distribution. Shall mean. Therefore, it is assumed here that not only the original plasma distribution is canceled out to make it uniform, but also that the original plasma distribution is further expanded.

Alternatively, in the impurity introducing method of the present invention, a step of adjusting the distribution of the substance in the vicinity of the substrate surface to have a distribution corresponding to the plasma distribution and supplying the substance into the chamber; Generating a plasma of the material after the material has equilibrated on the substrate surface.

In ordinary plasma generators, the power for exciting plasma such as high-frequency waves or microphone mouth waves has a limit in spatial uniformity. Therefore, in the impurity introduction method of the present invention, We propose a method that can obtain the impurity distribution that does not depend on the degree of the spatial uniformity by controlling the distribution of the substances excited by plasma.

For example, a material that is plasma-excited to offset this non-uniformity is provided. This makes it possible to introduce impurities with extremely high uniformity into a very shallow region from the substrate surface. Further, even with a substrate having a large diameter such as a semiconductor substrate or a liquid crystal display substrate, it becomes easy to control the uniformity of the impurity distribution.

The present invention enables the profile to be controlled with a high degree of accuracy in the introduction of impurities.The result is obtained by the point that the material is equilibrated on the surface of the substrate and then plasma is excited, and the power distribution of plasma excitation is used. The point of adjusting the substance on the substrate surface so as to cancel the distribution of the plasma (ion radical, neutral particle distribution) that is generated on the surface, and the substance on the substrate surface so that the plasma is gradually distributed on the substrate surface These methods include a method of adjusting the plasma doping or a combination thereof, and these methods enable plasma doping with a desired profile.

Further, according to the impurity introduction method of the present invention in which a substance containing an impurity is plasma-excited and the excited impurity is introduced into a substrate, a spatially arbitrary one is provided in a chamber in which the substrate is disposed. The substance is supplied so as to have a distribution, and the substance having the spatial distribution is excited by plasma to introduce impurities.

With this configuration, regions having different impurity distributions can be freely formed in the base body by a single impurity introduction process. Accordingly, in forming a semiconductor integrated circuit, a margin for mask alignment is not required, and further miniaturization and high integration can be achieved. In addition, it becomes possible to fabricate semiconductor devices having various different performances on a single substrate. In addition, it will be possible to respond quickly to high-mix low-volume production of semiconductor device products and improve the production efficiency of multi-product products. Here, the impurity profile includes the impurity distribution in the depth direction in addition to the in-plane impurity distribution.

In the present invention, the plasma is generated in a state where the supply of the substance is stopped. Plasma is generated with the supply and discharge of the substance stopped. Plasma is generated after the substance supplied into the chamber in which the substrate is placed is in an equilibrium state on the surface of the substrate. Alternatively, the flow rate of the substance is reduced to 10 O m e

After that, take measures such as generating plasma. Thereby, the flow of the substance to be supplied in the chamber can be stabilized quasi-statically. By exciting this stable substance with plasma, the distribution of impurities on the substrate surface is further improved. In this way, the fluctuation component generated by the flow of the substance is reduced, and the disturbance is suppressed only by the plasma. When the flow velocity is reduced to 10 Ome V or less, the phenomenon is that the temperature is almost at room temperature, and the distribution before plasma formation does not significantly change during plasma formation. Can be maintained.

In the present invention, plasma is generated after supplying a certain amount of the substance into the chamber. Here, the fixed amount of the substance to be supplied is determined according to the amount of impurities introduced into the substrate.

By doing so, it is possible to control the amount of impurities introduced to the surface of the substrate to a desired set amount. In addition, very shallow introduction can be controlled with high precision, and extremely shallow junctions can be formed with high precision.

Further, in the present invention, the supply of the substance into the chamber in which the substrate is disposed is performed through a microphone port nozzle. Here, the substance is a gas containing impurities. Alternatively, fine particles or fine droplets containing impurities may be used. The flow rate can be changed by arranging a large number of micro nozzles having a fine opening diameter and controlling each micro nozzle independently.

As a result, the spatial distribution of the substance in the chamber in which the substrate is disposed can be controlled with high accuracy, and the control of the amount of impurities on the surface of the substrate and the independent control of the spatial distribution are further promoted.

Further, the impurity introducing device of the present invention is an impurity introducing device for plasma-exciting a substance containing an impurity and introducing the impurity into the substrate from the excited substance, wherein: The apparatus includes a means for supplying a certain amount of the substance into the chamber, a means for evacuating the inside of the chamber, and a plasma generating means for plasma-forming the certain amount of the substance. The means for supplying a certain amount of the substance has a mechanism for measuring and storing the substance, and this mechanism controls the volume, pressure, and temperature of the storage container to maintain the substance at a constant amount. ing. Further, the storage container stores an amount of the substance corresponding to the amount of impurities introduced into the base.

With this configuration, the introduction of impurities to a large-diameter semiconductor substrate or a substrate that is a liquid crystal display substrate can be performed in a short time in a single wafer process. As a result, the mass production capacity of semiconductor devices or liquid crystal display devices is improved, and production costs can be reduced. The substance is a gas, fine particles, or fine droplets.

For example, the gas includes any of B ₂ H ₆ , BF ₃ , As H ₃ , and PH ₃ . Further, any of B, As, P, Sb, In, and A1 can be used as the fine particles or solid. Here, the term “droplet” refers to a solution in which these fine particles and gas are dissolved or turbid. In addition, the surface may be covered so as to be wet.

Further, the timing of generating the plasma may be determined based on a result of simulating the profile of the impurity concentration in the vicinity of the surface of the base and simulating the result. Furthermore, instead of simulating the profile of the impurity concentration, at least one selected from the group consisting of gas, fine particles or fine droplet flow velocity, number of gas molecules, and pressure was measured, and the standard deviation reached less than 2%. Plasma may be generated in the state.

The present invention makes it possible to control the profile with high precision in the introduction of impurities.It is based on the point that the substance is equilibrated on the surface of the substrate and then plasma is excited, and the power distribution of plasma excitation is used. The point of adjusting the substance on the substrate surface so as to offset the distribution of the resulting plasma (ion radial, distribution of neutral particles) is that the plasma is gradually distributed on the substrate surface. These include methods for adjusting the material or a combination thereof, and these methods enable plasma doping with a desired profile. <Brief description of drawings>

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

FIG. 2 is a schematic cross-sectional view of a main body of the impurity introduction device for describing the impurity introduction method according to the first embodiment of the present invention. FIG. 3 is a diagram showing a drive timing of the impurity introduction device according to the first embodiment of the present invention.

FIG. 4 is a diagram showing a drive timing of the impurity introduction device according to the second embodiment of the present invention.

FIG. 5 is a schematic cross-sectional view of a main body of the impurity introduction device according to the third embodiment of the present invention.

FIG. 6 is a schematic cross-sectional view of another impurity introduction device according to the fourth embodiment of the present invention.

FIG. 7 is a schematic cross-sectional view of a main body of an impurity introduction device for describing an impurity introduction method according to a fifth embodiment of the present invention.

FIGS. 8A and 8B are explanatory diagrams of a fifth embodiment of the present invention. FIG. 8A is a diagram showing plasma intensity, FIG. 8B is a diagram showing distribution of a supplied substance (dopant), and FIG. It is a figure which shows a distribution.

FIG. 9 is a schematic cross-sectional view of a main body of an impurity introduction device for describing an impurity introduction method according to the sixth embodiment of the present invention.

FIG. 10 is a plan view of a silicon wafer substrate showing an impurity distribution according to the sixth embodiment of the present invention.

FIG. 11 is a graph showing characteristics of the MOSFET formed according to the sixth embodiment of the present invention.

FIG. 12 is a schematic cross-sectional view of a main body of an impurity introduction device for describing an impurity introduction method according to a seventh embodiment of the present invention.

FIG. 13 is a graph showing an impurity distribution according to the seventh embodiment of the present invention. FIGS. 14A and 14B are explanatory diagrams of the eighth embodiment of the present invention. FIG. 14A is a diagram showing the plasma intensity, FIG. 14B is a diagram showing the distribution of the supplied material (dopant), and FIG. It is a figure which shows a distribution. In the figure, reference numeral 1 denotes a vacuum chamber, 2 denotes a plasma generating unit, 3 denotes a power source, 4 denotes a holding table, 5 denotes a substrate to be processed, 6 denotes a vacuum pump, 7a and 7b denote measuring chambers, 8 and 14 is a nozzle, 9 is a supply device, 10 is a mass flow controller, and 11 is a pressure A gyrator, 1 2 is a plasma, 1 3 is a rotary drive shaft, 1 5 is a gas flow, 1 6 is a high frequency power supply, 1 7 is a counter electrode, 1 8 is a gas introduction pipe, 1 is a micro nozzle, 2 is a deflected plasma, Pl and P2 are pressure gauges, and T1 and T2 are thermometers. <Best mode for carrying out the invention>

(First Embodiment)

Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. The impurity introduction device is characterized in that the impurity introduction profile can be adjusted by adjusting the distribution of the substance near the surface of the base. FIG. 1 is a cross-sectional view schematically showing an impurity introducing device of the present invention, and FIG. 2 is a main body of the above-described device for explaining the impurity introducing method of the present invention.

As shown in FIG. 1, this apparatus includes a vacuum chamber 1, a plasma generator 2 and a power supply 3 for supplying power thereto, and a holding table 4 is provided in the vacuum chamber 11, and a processing substrate 5 is provided. Is placed. Then, a vacuum pump 6 for adjusting the degree of vacuum of the vacuum chamber 11 is provided. The main body of the impurity introduction device is configured in this way, but this device is a single-wafer type and requires the minimum volume of the entire vacuum chamber 1 in order to enable rapid processing. That is important. Here, the plasma generation unit 2 is a helicon wave plasma source, an ECR (ElectronCytronTronOnRec ancen) plasma source, or the like, and a plasma generation source having a high response speed is preferable. With such a plasma source, a substance containing an impurity to be introduced into the substrate 5 to be processed, here a gas, is plasma-excited.

In the supply system of the gaseous substance containing the above impurities, the measuring chambers 7a and 7b are provided, and the gaseous substance is supplied from the nozzle 8 to the vacuum chamber 1 through the measuring chamber 17a or 7b in a fixed amount. Is done. Here, the measuring chambers 7a and 7b are configured to store a certain amount of gaseous substances. This storage amount is determined by the volume of the measuring chambers 7a and 7b, gas temperature, and gas pressure, and monitored by thermometers Tl and Τ2 and pressure gauges Ρ1 and Ρ2, respectively. The gas temperature and pressure are controlled stably by the unit and the pressure control unit. This measuring chamber will be added as needed. The gas supply to the measuring chamber 1 is performed through the mass flow controller 10 from the supply device 9. The amount of gas supplied to the measuring chambers 7 a and 7 b is strictly controlled by the pressure regulator 10. Can be specified. Here, the gas is B ₂ H ₆ , BF ₃ , As H ₃ , PH ₃ , or a gas obtained by diluting them with an inert gas.

The impurity introduction apparatus of the present invention excites a substance containing an impurity by plasma excitation to dope an impurity into a substrate. An RIE (Reactive Ion E) which continuously supplies a reaction gas to a reaction chamber and generates a plasma. Unlike dry etching (CVD) or CVD (Chemical Vapor Dep osition), the impurity introduction apparatus of the present invention uses a certain amount of gas corresponding to the impurity introduction amount (dose amount) to the substrate. It can be converted to plasma with high accuracy. With this configuration, it is possible to introduce an impurity having an extremely shallow depth, and it is possible to control the impurity introduction depth with high precision.

In addition, it is possible to rapidly introduce impurities into a substrate, which is a large-diameter semiconductor substrate, so that single-wafer processing can be performed in a short time. For this reason, it becomes possible to form a highly accurate and highly reliable semiconductor device with high productivity. When used for a liquid crystal display substrate, the mass production capacity of the liquid crystal display device is improved, and the production cost can be reduced. In the impurity introducing apparatus shown in FIG. 1, the holding table 4 may be made of a conductor, and a direct current (DC) power supply or an RF power supply, which is a high-frequency power supply, may be attached to the holding table 4. Here, the RF power supply is a high-frequency power supply having a frequency of 100 kHz to 10 MHz. A DC potential in the range of several eV to 1 keV can be formed between the plasma generated by these power supplies and the substrate 5 to be processed. Also, a mechanism that can rotate the holding table 4 may be attached. By applying a rotation of, for example, about 10 rpm to the substrate 5 to be processed on a horizontal plane by this rotating mechanism, the uniformity of the impurity dose in the surface of the substrate 5 to be processed is further improved.

In addition, as substances containing impurities, in addition to those which are gas at normal temperature and normal pressure as described above, fine particles such as B, As, P, Sb, In, Al, and Si fine particles can be used. A solid, a liquid containing the above impurities, or a solid particle surrounded by a liquid may be used. However, in this case, the supply system shown in Fig. 1 will be slightly different It is necessary to be able to supply a certain amount of substances containing power impurities.

Next, the impurity introduction method of the present invention will be described with reference to FIGS. Here, the same parts as those shown in FIG. 1 are denoted by the same reference numerals. 3 (a) to 3 (c) are timing charts showing the driving states of the vacuum pump 6, the gas supply nozzle 8, and the plasma excitation power supply 3, respectively. As shown in FIG. 2, for example, a silicon wafer having a diameter of 30 μππππφ is placed as a substrate 5 to be processed on the holding table 4 and fixed by electrostatic attraction. Then, after the vacuum pump 6 is operated to reduce the degree of vacuum in the vacuum chamber 11 to about 10 ″ ³ Pa, the gas exhaust by the vacuum pump 6 is stopped.

After such a state, the above-mentioned fixed amount of the gas substance in the measuring chambers 7a and 7b is supplied into the vacuum chamber 11 through the nozzle 8. Here, since the vacuum pump 6 is in a stopped state, the flow rate of the gas substance flowing into the vacuum chamber 11 decreases with time. When the flow of the gaseous substance near the surface of the substrate 5 to be processed or in the vacuum chamber 11 is in an equilibrium state and is stabilized in a quasi-static state, the plasma generator 2 is driven by the power source 3 to vacuum the vacuum. Excitation of the gas substance filling chamber 1 into plasma (section P: see Fig. 3). Here, when the flow rate of this gaseous substance becomes equal to or lower than a predetermined value (converted value: 100 meV) by actual measurement or simulation, the plasma generation unit 2 is driven to start the vacuum chamber. Excitation of the gas substance filling 1 into plasma.

In this way, the plasma 12 having a uniform spatial distribution is generated, and the surface of the substrate 5 to be processed is exposed to the plasma 12 for a predetermined time (for example, one minute). Here, the plasma 12 is a thermal non-equilibrium plasma in which the electron temperature and the ion temperature are extremely different, and the ion temperature is usually several tens of degrees and its thermal kinetic energy is small. By the above-described plasma irradiation of the substrate 5 to be processed, a substance containing impurities to be introduced is ion-implanted into the surface of or within the substrate 5 to be processed or in the form of adsorption or low energy (several eV to lkeV as described above). Introduced in form. Here, in the adsorption mode, the substance is physically adsorbed on the surface of the substrate 5 to be processed, and active species such as neutral radicals mainly generated by the plasma excitation are chemically adsorbed. In the ion implantation mode, the ionized impurity material in the above substance is ionized, but part of the ionized material is injected into the surface by thermal motion. (As described above, the thermal kinetic energy is small and the amount is small. At the same time, the ion implantation is mainly accelerated by a DC voltage such as an ion sheath generated on the surface of the plasma 12 and the surface of the substrate 5 to be processed or a so-called self-bias.

After that, RTA (rapid heat treatment) is performed in another chamber of a multi-chamber configuration, not shown in FIG. In this way, according to the impurity introduction method of the present invention, uniform and shallow impurity introduction can be performed near the surface of the substrate 5 to be processed. Further, in order to supply a certain amount of gaseous substance into the vacuum chamber 11, the amount of impurities introduced to the surface of the base can be controlled so as to be a desired set amount.

(Second embodiment)

In the first embodiment, as shown in the timing chart of FIG. 3, the plasma excitation is performed while supplying a substance that is an impurity, but in the present embodiment, the timing of the plasma excitation is changed. As shown in the timing chart of Fig. 4, the plasma excitation is performed after the supply of impurities is stopped.

Fig. 4 (a) shows the timing chart of the vacuum pump. That is, as described above, after the degree of vacuum in the vacuum chamber 11 is reduced to about 10 to ³ Pa, the gas exhaust is stopped (FIG. 4B). Then, after supplying the above-mentioned fixed amount of gaseous substance in the measuring chambers 7a and 7b through the nozzle 8 into the vacuum chamber 11, the supply is also stopped by an electromagnetic valve (not shown).

Thereafter, the plasma generator 2 is driven to generate the plasma 12 (FIG. 4 (c)). Thereafter, impurities are introduced into the surface of the substrate 5 to be processed during the interval P in the same manner as described above. In such a method, the measuring chambers 7a and 7b are not necessarily required. This is because even if a gas substance is directly introduced into the vacuum chamber 11 from the supply device 9 shown in FIG. 1, the amount of the gas substance can be strictly defined by the mass flow controller 10.

Also in this case, as described above, the gas substance is plasma-excited when the flow of the gas substance in the vacuum chamber 11 becomes equilibrium and is stabilized in a quasi-static state. (Third embodiment)

Next, a third embodiment of the present invention will be described with reference to FIG.

This embodiment is different from the first and second embodiments in that the impurity-containing gas introduced into the vacuum chamber 11 is intentionally given a predetermined spatial distribution, and the impurity dose to the substrate 5 to be processed is changed. It is characterized by improving the uniformity of the amount. FIG. 5 is a schematic cross-sectional view of a main body of the impurity introduction device of the present invention. Here, the same parts as those in the first embodiment are denoted by the same reference numerals.

This apparatus is characterized in that a nozzle 14 having a large number of ejection ports is connected to a measuring chamber, and is adjusted so as to have a distribution in the ejection amount of gas containing impurities from the nozzle 14.

In FIG. 5, as described in the first embodiment, a vacuum chamber 11, a plasma generator 2 and a power supply 3 for supplying power thereto are provided, and a holding table 4 is provided in the vacuum chamber 11. The substrate 5 to be processed is provided. Here, the rotary drive shaft 13 is attached to the holding base 4 so as to rotate in the direction of the arrow.

Further, a vacuum pump 6 for adjusting the degree of vacuum of the vacuum chamber 11 is provided. As shown in FIG. 5, a nozzle 14 having a large number of ejection ports is connected to the measuring chamber 17 described above, and this nozzle 14 is inserted into the vacuum chamber 11. Here, the nozzle 14 may be tubular or may have a planar spread. Here, it is preferable that the ejection port is composed of an aggregate of micro nozzles having a diameter of / order. Then, when the gas is introduced from the measuring chamber 7, a spatially non-uniform gas flow 15 can be generated as shown by the distribution of arrows in FIG.

By controlling the amount of gas supplied from the nozzle in this way, it is possible to offset the variation in plasma caused by various conditions such as the position and to form a uniform distribution.

(Fourth embodiment) Next, an impurity introducing device according to a fourth embodiment of the present invention will be described. As shown in Fig. 6, unlike the helicon wave plasma and ECR plasma generation, this impurity introduction device generates plasma by applying a high frequency of 13.56 MHz to parallel plate electrodes. . In FIG. 5, as described in the first embodiment, a holding table 4 is provided in a vacuum chamber 1 and a substrate 5 to be processed is placed thereon. Here, a high-frequency power supply 16 is attached to the holding base 4 made of a conductor, and serves as one electrode of a parallel plate electrode. Further, a counter pump 17 and a vacuum pump 6 for adjusting the degree of vacuum of the vacuum chamber 11 are provided.

The counter electrode 17 described above is provided with a large number of ejection ports, and is connected to the measurement chamber 17 through the gas introduction pipe 18. Here, the ejection port is composed of an aggregate of micro nozzles with a diameter of the order of 10 x m. Then, when introducing the gas substance from the measuring chamber 17 into the vacuum chamber 1, a spatially non-uniform gas flow 15 can be generated as shown in FIG. In this example, since the electric field is weaker in the vicinity of the periphery of the holding base 4 and the counter electrode 17 constituting the electrode than in the center, the gas flow 15 in the periphery should be adjusted to have a higher concentration. As a result, the plasma distribution becomes uniform in the substrate plane.

Note that a magnetic field parallel to the parallel plate electrodes may be applied by a permanent magnet or the like, and even in this case, high-density plasma can be easily generated. The magnetic field shown in Fig. 6 represents this, as well as the electric field due to high frequency.

(Fifth embodiment)

Next, a fifth embodiment will be described with reference to FIGS. Even in this case, the method described in the first embodiment is basically used, but the present embodiment is characterized in that the introduction of the gas substance has a spatial distribution as described above. Normally, the generated plasma has a spatial distribution because the electromagnetic energy density of the high frequency or microwave used for plasma excitation has a spatial distribution and is not always uniform.

Therefore, in this embodiment, the spatial distribution of the gaseous substance is so set as to cancel the spatial distribution of the plasma generated for the above reason (hereinafter referred to as the plasma distribution). Hold the cloth. Here, the above plasma distribution can be measured by well-known plasma emission spectroscopy, Faraday force or Langmuir probe.

As shown in FIG. 7, for example, a substrate 5 to be processed is placed on a holding table 4, fixed by electrostatic attraction, and rotated by a rotation drive shaft 13. For example, rotate horizontally at 20 rpm. Then, the vacuum pump 6 is operated to set the degree of vacuum in the vacuum chamber 11 to about 10 Pa to ³ Pa, and then gas exhaust by the vacuum pump 6 is stopped. After such a state, a certain amount of the above-mentioned substance for generating plasma in the measuring chamber 7 is introduced into the vacuum chamber 1 through the nozzle 14. Here, the nozzle 14 is provided with a large number of micro nozzles 19, and a spatially non-uniform gas flow 15 is generated in the vacuum chamber 11 through the micro nozzle 19. Then, when the flow of the substance for plasma generation in the vicinity of the surface of the substrate 5 to be processed or in the vacuum chamber 11 is in an equilibrium state and is stabilized in a quasi-static state, the plasma generation unit 2 is turned on by the power source 3. Is driven to excite the plasma generating substance (gas substance) filling the vacuum chamber 1 with plasma.

For example, when the flow rate of the gaseous substance falls below a predetermined value (converted value: lOOmeV), the plasma generation part is driven to excite the gaseous substance introduced unevenly into the vacuum chamber 11 by plasma excitation. I do. By the plasma excitation, the gas flow 15 is adjusted so that a large amount of gas substance exists in a space having a low electromagnetic energy density and a small amount of gas substance exists in a space having a high electromagnetic energy density. Then, the surface of the substrate 5 is exposed to plasma for a predetermined time (for example, one minute). Thereafter, the same processing as that described in the first embodiment is performed.

Explaining this result with reference to FIG. 8, as shown in FIG. 8 (a), a plasma distribution is generated from the spatial distribution of the electromagnetic energy density of the high frequency or microwave used for plasma excitation. That is, when viewed from the rotating substrate 5 to be processed, the plasma distribution usually has a concentric distribution shape. In order to offset the distribution of plasma (distribution of ions, radicals, and neutral particles) resulting from the power distribution and the like of the plasma excitation, the material (gas) for generating plasma shown in Fig. 8 (b) is canceled out. Have a spatial distribution of Here, the spatial distribution may be in the vicinity of the surface of the substrate 5 to be processed, or may be in the vacuum chamber 1. Such a spatial distribution of the gaseous substance is obtained from a simulation or a trial experiment of a gas flow taking into account a so-called thermal motion. Here, also in this case, the spatial distribution of the gaseous substance viewed from the rotating target substrate 5 is shown. When a gas substance having such a spatial distribution is excited by plasma, a plasma having a uniform spatial distribution is generated as viewed from the substrate 5 to be processed, as shown in FIG. 8 (c). It will be exposed to various plasmas. In this way, it is possible to uniformly introduce impurities in the surface of the substrate 5 to be processed. In addition, the supply of the gaseous substance through the micro nozzle as described above makes it possible to control the spatial distribution of the substance in the chamber in which the base is arranged with high precision.

As described in the first embodiment, the impurities introduced by the plasma irradiation on the substrate 5 to be processed are introduced in the form of adsorption or ion implantation with low energy. Here, in the adsorption form, active species such as neutral radicals are chemically adsorbed. In the ion implantation mode, the ionized material is accelerated and implanted by plasma and an ion sheath generated on the surface of the substrate 5 or a DC voltage such as a so-called self-bias. The results shown in FIGS. 8 (a) to 8 (c) show that by controlling the spatial distribution of the gaseous substances, the introduction of impurities in the form of adsorption can also be adjusted.

(Sixth embodiment)

Next, an impurity introduction method according to the sixth embodiment will be described. This embodiment is different from the third embodiment in that the gas substance introduced into the vacuum chamber 11 is intentionally given a predetermined spatial distribution, and the impurity dose to the substrate 5 to be processed is not in-plane. This is the case where control is performed so as to be uniform. In this case, the same impurity introducing device as that described in the second embodiment may be used.

In the main body of the impurity introducing apparatus shown in FIG. 9, for example, a substrate 5 to be processed is placed on a holding table 4 in a vacuum chamber 11 and fixed by electrostatic attraction. Then, as shown in the figure, the vacuum pump 6 provided at the lower left end of the vacuum chamber 11 is operated. Further, the gas substance to the vacuum chamber 11 is introduced from the measuring chamber 17 through a nozzle 8 provided at the upper right end of the vacuum chamber 11. After the gas substance flows from the upper right to the lower left in the vacuum chamber 11 in this way, the plasma generator 2 is driven by the power source 3 to uniformly distribute the gas substance introduced into the vacuum chamber 11. Excitation of plasma.

In this way, as shown schematically by the oblique lines in FIG. 9, the deflected plasma 20 whose plasma density decreases from right to left is generated. Then, the surface of the substrate 5 is exposed to the deflected plasma 20 for a predetermined time (for example, 10 seconds). Thereafter, the same processing as that described in the first embodiment is performed.

The result will be described with reference to FIG. FIG. 9 shows the impurity distribution in the silicon wafer surface after the boron impurity was introduced into a silicon wafer of 300 mιηφ (substrate 5 to be processed). The substrate 5 to be processed shows a sheet resistance distribution. The sheet resistance increases in the direction of the arrow in FIG. Here, the upper part of the substrate 5 shown in FIG. 10 corresponds to the right-hand side in FIG. 9, and the lower part of the substrate 5 shown in FIG. 10 corresponds to the right-hand side in FIG. As described above, by imparting a spatial distribution of the gas substance in the vacuum chamber 11, impurities having desired non-uniformity can be introduced in the surface of the substrate 5 to be processed.

FIG. 11 shows the transistor characteristics after introducing impurities having non-uniformity as shown in FIG. 10 and performing channel doping for the MOSF, and shows the drain current and the drain current when the gate voltage is constant. The relationship between the drain voltages is shown. Here, X and Υ in the figure correspond to the M OS F の of the semiconductor chip at the Χ and Υ positions shown in FIG. 10, respectively. In this way, it becomes possible to manufacture a large number of semiconductor chips having different MOS FETs with different characteristics by introducing impurities into the substrate 5 once.

(Seventh embodiment)

Next, another impurity introduction method according to the seventh embodiment will be described. The impurity introducing device in this case is the same as that described in the third embodiment shown in FIG. However, in this case, there is no rotary drive shaft 13 and the substrate 5 to be processed is not rotated. In the main body of the impurity introducing apparatus shown in FIG. 11, for example, a substrate 5 to be processed is placed on a holding table 4 in a vacuum chamber 11 and fixed by electrostatic attraction. And true After the empty pump 6 is operated to reduce the degree of vacuum in the vacuum chamber 11 to about 10 to ³ Pa, the gas exhaust by the vacuum pump 6 is stopped.

Then, a substance (gas substance) for plasma generation in the measuring chamber 17 is introduced into the vacuum chamber 1 through the nozzle 14. Here, the nozzle 14 is provided with a large number of micro nozzles 19, and a spatially non-uniform gas flow 15 is generated in the vacuum chamber 11 through the micro nozzles 19. Then, the plasma generating unit 2 is driven by the power source 3 to excite the gas substance introduced non-uniformly into the vacuum chamber 11, and the surface of the substrate 5 to be processed is plasma-treated for a predetermined time (for example, 10 seconds). Exposure. Thereafter, processing similar to that described in the first embodiment is performed.

As a result, as shown in FIG. 13, plasma having a step-shaped plasma density is generated in the vacuum chamber 11. That is, it is possible to generate plasma that decreases stepwise from the left side to the right side of the substrate 5 to be processed. In this case, the supply of the gaseous substance through the microphone nozzle can control the spatial distribution of the substance in the chamber in which the substrate is disposed with high precision. Further, control of the amount of impurities on the surface of the base and free control of the distribution thereof are further promoted.

Therefore, it becomes possible to introduce non-uniform impurities with higher precision than the case shown in FIG. In addition to the channel doping of the MOSFET, formation of a diffusion layer serving as a source-drain region and formation of a well layer can be realized with high accuracy. In the seventh embodiment of the present invention, since it is easy to freely control the amount of impurities introduced into the surface of the semiconductor substrate when the impurities are introduced into the surface of the semiconductor substrate, regions having different impurity distributions are formed in the same substrate. Can be freely formed by a single impurity introduction treatment. Therefore, in forming a semiconductor integrated circuit, a margin for mask alignment is not required, and further miniaturization and high integration can be achieved. In addition, the response to high-mix low-volume production of semiconductor device products will be accelerated. In addition, in the trial manufacture of semiconductor devices, semiconductor chips in which impurities are introduced under a number of different conditions can be formed on a single silicon wafer, so that the optimization of semiconductor device manufacturing can be accelerated. In addition, in manufacturing semiconductor devices, it becomes possible to quickly respond to customer needs.

(Eighth embodiment) In the above embodiments, the semiconductor substrate forming the semiconductor device has been described as the substrate to be processed. However, the present invention is applied to the case where the substrate to be processed is a matrix substrate forming a liquid crystal display device. Is done. This is realized by using the same impurity introduction device as that used in the first embodiment.However, in the case of a large-area substrate, the plasma excitation power is easily distributed in the vacuum chamber, and FIG. As shown in a), the edges are particularly likely to be low. Therefore, in this case, as shown in FIG. 14 (b), the gas supply amount is increased at the end as an eighth embodiment of the present invention, and as a result, as shown in FIG. 14 (c), A uniform plasma density can be realized. Therefore, a large-area substrate can be formed.

Further, the present invention is not limited to the above embodiments, and the embodiments can be appropriately changed within the scope of the technical idea of the present invention. For example, in the third and seventh embodiments, a case where a certain amount of a plasma generating substance (gas substance) is introduced from the measuring chamber 17 into the vacuum chamber 11 and the plasma is excited therefrom. Although described, a similar effect is produced even if a gaseous substance is introduced from the supply device 9 through the mass flow controller 10 without passing through the measuring chamber 17. In this case, plasma excitation may be performed while operating the vacuum pump 6 to exhaust gas substances. In this case, the impurity doping amount can be controlled by the total introduction amount of the gas substance obtained by integrating from the mass flow controller 10. A feature of the impurity introduction device of the present invention is that rapid treatment is possible. Therefore, the plasma generation unit 2 may generate a high-density plasma such as ICP (Inductiv eCooledPla sma). However, even in this case, it is necessary to enable a high-speed response as described above.

In the above embodiment, the method of introducing impurities under reduced pressure has been described. It is also possible to introduce impurities under normal pressure. Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention.

This application is based on Japanese Patent Application No. 2003-164249 filed on June 9, 2003 And its contents are hereby incorporated by reference. Industrial applicability>

As described above, the present invention relates to an impurity introduction method for plasma-exciting a substance containing an impurity and introducing an impurity into the substrate from the excited substance, wherein the space of the substance in one chamber in which the substrate is disposed is provided. Adjust the distribution according to the plasma distribution. Alternatively, the impurity introduction method of the present invention comprises the steps of: adjusting the distribution of the substance in the vicinity of the substrate surface to have a distribution corresponding to the plasma distribution, and supplying the substance into the chamber; Generating a plasma after reaching an equilibrium state.

For this reason, the present invention enables the introduction of highly uniform impurities into an extremely shallow region from the substrate surface, even if the spatial uniformity of power for plasma excitation such as high frequency or microwave is poor. It is possible to provide an impurity introduction method having an effect of reducing the impurity concentration.

Claims

The scope of the claims

1. An impurity introduction method for exciting a substance containing an impurity to be introduced by plasma, and introducing a plasma of the impurity into the substrate from the excited substance, wherein at least a part of the distribution of the plasma is offset. A method of introducing impurities, wherein the distribution of the substance in the vicinity of the surface of the substrate is adjusted so as to obtain.

2. The method for introducing impurities according to claim 1, wherein

Adjusting the distribution of the substance in the vicinity of the surface of the substrate so that at least a part of the distribution of the plasma can be offset, and supplying the substance into a chamber in which the substrate is disposed;

Generating plasma after the substance is in an equilibrium state on the substrate surface.

3. The method for introducing impurities according to claim 2, wherein

The step of supplying the substance is an impurity introduction method in which the impurity introduced into the base is adjusted to be uniform.

4. The method for introducing impurities according to claim 2, wherein

The step of supplying the substance is a method of introducing impurities in which impurities introduced into the base are adjusted to have a predetermined distribution.

5. The method for introducing impurities according to any one of claims 1 to 4, wherein

A method for introducing impurities, wherein plasma is generated while the supply of the substance is stopped.

6. The method for introducing impurities according to any one of claims 1 to 4, wherein

A method of introducing impurities, characterized in that plasma is generated while supply and discharge of the substance are stopped.

7. An impurity introducing method, comprising: plasma-exciting a substance containing an impurity; and introducing the impurity into the substrate from the excited substance, A method of introducing impurities, wherein plasma is generated in a state where supply of the substance into one chamber in which the substrate is disposed is stopped.

8. A method for introducing an impurity into a substrate, wherein the material containing the impurity is plasma-excited, and the impurity is introduced into the substrate from the excited material,

A method of introducing impurities, wherein plasma is generated in a state in which supply and discharge of the substance into and out of a chamber in which the substrate is disposed are stopped.

9. A method for introducing an impurity into a substrate, comprising exciting a substance containing an impurity by plasma, and introducing the impurity into the substrate from the excited substance.

An impurity introduction method, characterized in that plasma is generated after the substance supplied into one of the chambers in which the substrate is placed is in an equilibrium state on the surface of the substrate.

10. The method for introducing impurities according to any one of claims 1 to 9, wherein

Plasma is generated after the flow rate of the substance becomes equal to or less than 10 OmeV in terms of a conversion rate, and plasma is generated.

11. The method for introducing impurities according to any one of claims 1 to 10, wherein

A method of introducing impurities, comprising: generating plasma after supplying a certain amount of the substance into a champer on which the base is arranged.

12. The method for introducing impurities according to claim 11, wherein

The method of introducing impurities, wherein a certain amount of the substance to be supplied is determined according to an amount of impurities to be introduced into the substrate.

13. The method for introducing impurities according to any one of claims 1 to 12, wherein

The method of introducing impurities, wherein the supply of the substance into the chamber in which the substrate is disposed is performed through a micro nozzle while adjusting the distribution of the impurities.

14. The method for introducing impurities according to any one of claims 1 to 13, wherein

The method for introducing impurities, wherein the substance is a gas.

15. The method for introducing impurities according to claim 14, wherein: A method for introducing impurities into which the gas contains any of B ₂ H ₆ , BF ₃ , As H ₃ , and PH ₃ .

16. The method for introducing impurities according to any one of claims 1 to 13, wherein

The impurity introducing method, wherein the substance is fine particles.

17. The method for introducing impurities according to any one of claims 1 to 13, wherein

The method for introducing impurities, wherein the substance is a fine droplet.

18. The method for introducing impurities according to claim 16 or claim 17, wherein the fine particles contain any one of B, As, P, Sb, In, and A1. Introduction method.

19. An impurity introducing apparatus for exciting a substance containing an impurity by plasma and introducing the impurity into the substrate from the excited substance,

A chamber for disposing the substrate,

Means for supplying the substance into the chamber;

Means for evacuating the inside of the chamber,

An impurity introduction device, comprising: a plasma generating means for performing plasma while maintaining the substance in an equilibrium state.

20. The impurity introducing apparatus according to claim 19, wherein

An impurity introduction device, wherein the means for supplying the substance has a mechanism for measuring and storing the substance.

21. The impurity introducing apparatus according to claim 20, wherein

A mechanism for measuring and storing the substance, wherein the apparatus controls the volume, pressure, and temperature of a storage container to maintain the substance at a constant amount.

22. The impurity introducing apparatus according to claim 20, wherein the container for measuring and storing the substance comprises a substance having an amount corresponding to an impurity amount introduced into the base. Impurity introducing device, characterized in that the impurity introducing device can be stored.

23. The impurity introducing apparatus according to any one of claims 19 to 22, wherein An impurity introducing device, wherein the substance is a gas, fine particles or fine droplets.

24. In the impurity introducing method according to any one of claims 1 to 18,

Simulating the behavior of the substance,

An impurity introduction method wherein the timing for generating the plasma is adjusted based on the simulation result.

25. The method for introducing an impurity according to any one of claims 1 to 18 and 24 or the apparatus for introducing an impurity according to any one of claims 15 to 23. A semiconductor device formed by using

A semiconductor device having an element region formed by introducing the impurity.

26. The semiconductor device according to claim 25, wherein

The semiconductor device according to claim 1, wherein the element region includes a plurality of impurity introduction regions having different impurity profiles.