Classifications

• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P70/00—Cleaning of wafers, substrates or parts of devices
  • H10P70/10—Cleaning before device manufacture, i.e. Begin-Of-Line process
  • H10P70/15—Cleaning before device manufacture, i.e. Begin-Of-Line process by wet cleaning only
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P32/00—Diffusion of dopants within, into or out of wafers, substrates or parts of devices
  • H10P32/10—Diffusion of dopants within, into or out of semiconductor bodies or layers
  • H10P32/12—Diffusion of dopants within, into or out of semiconductor bodies or layers between a solid phase and a gaseous phase
  • H10P32/1204—Diffusion of dopants within, into or out of semiconductor bodies or layers between a solid phase and a gaseous phase from a plasma phase

Definitions

• the present invention relates to a method for forming an impurity introduction layer, a method for cleaning an object to be processed, and a method for manufacturing an impurity introduction device and device.
• the present invention relates to a method for forming an impurity-introduced layer by introducing particles into an object to be processed, such as a silicon substrate, by plasma doping ion implantation, deposition, and the like, particularly in a manufacturing process of a semiconductor, a liquid crystal, and the like.
• an object to be processed such as a silicon substrate
• plasma doping ion implantation, deposition, and the like particularly in a manufacturing process of a semiconductor, a liquid crystal, and the like.
• Conventional methods for cleaning semiconductor silicon substrates include the use of a solvent solution such as a mixed solution of hydrofluoric acid, sulfuric acid and aqueous hydrogen peroxide, a mixed solution of aqueous hydrogen peroxide and a mixed solution of aqueous ammonia and hydrogen peroxide.
• a method of inserting a silicon substrate is used. For example, after boron is ion-implanted, a heat treatment is performed on the silicon substrate to diffuse it. Before the heat treatment, the silicon substrate is cleaned by hydrofluoric acid, sulfuric acid, and hydrogen peroxide diluted to a predetermined concentration.
• Tanks such as a mixed solution of water, a mixed solution of hydrochloric acid and hydrogen peroxide, and a mixed solution of aqueous ammonia and hydrogen peroxide, and a tank of ultrapure water are arranged side-by-side, and the combination of solvents and the cleaning time are adjusted according to the application. Cleaning the silicon substrate.
• ion implantation is used as a method for introducing particles into a silicon substrate of a semiconductor.
• plasma doping is expected as a next-generation method that can efficiently introduce particles with extremely low energy.
• the object to be processed after the particles are introduced such as a silicon substrate
• the object to be processed after the particles are introduced has a lower level of metal contamination and the like derived from the impurity introduction device than before the introduction. Is generally reduced. Metal contamination causes a reduction in the yield of semiconductor devices.
• hydrofluoric acid has a higher cleaning ability for metal contamination than a mixed solution of sulfuric acid and hydrogen peroxide solution. Therefore, at present, a solvent containing hydrofluoric acid is often used for cleaning the silicon substrate after introducing the particles.
• the atomic concentration is 1 E 18 t 01113 / particles (- 111 3 become depth 1 5 nm or less, low in particular such that the following 1 0 nm
• cleaning the silicon substrate after the particles are introduced and before the heat treatment has a problem that did not appear in the past, that is, when the particles are introduced into such a shallow portion.
• the silicon substrate is cleaned by the conventional method, the particles introduced as dopants are washed away in the cleaning process, so that the number of particles electrically activated by the subsequent heat treatment is reduced.
• the characteristics described above are not obtained.
• Plasma doping involves not only doping by accelerating charged particles but also introducing particles into the silicon substrate by adsorption and permeation of radicals and gases onto one main surface of the object to be processed, such as the silicon substrate. Is done.
• the introduction of particles by radicals and gases is a very low energy introduction and, unlike the behavior of charged particles, is introduced into a shallow part of the silicon substrate surface regardless of the accelerating voltage.
• a certain level of acceleration voltage for example, several hundred volts
• the particles introduced at such a low energy in the entire dopant are washed away by washing, so that there arises a problem that desired sheet resistance characteristics are not obtained as described above.
• cleaning a semiconductor substrate such as a silicon substrate is indispensable for maintaining the yield of semiconductor devices.
• contamination level has reached the same level as compared to ion implantation in manufacturing, and cleaning methods after doping are important.
• a method is widely used in which a resist is patterned on a silicon substrate, for example, and an impurity is introduced into a portion where one main surface of the silicon substrate is exposed.
• the resist is applied to the silicon substrate in a desired pattern before the impurity is introduced, and is removed after the impurity is introduced and before the annealing step.
• the resist is removed by irradiating the resist with oxygen plasma, a so-called asshing method. If particles are introduced into the shallow part of one main surface of the polysilicon substrate, the resist is removed before annealing (thermal treatment). In the resist removal process that is performed, if the resist is removed by a conventional method, particles introduced as a dopant are removed together with the resist.
• the present invention has been made in view of the above-mentioned circumstances, and after introducing particles and other impurities into a semiconductor substrate (solid substrate) such as a silicon substrate, the solid substrate before heat treatment is required to maintain the yield of electronic devices. It is an object of the present invention to provide a method for cleaning a solid substrate which can be cleaned to a certain level and does not reduce introduced particles in a cleaning step.
• the present inventors have studied plasma doping in which the state of particles injected into a solid substrate (for example, a silicon substrate) from plasma is changed between a case where ions are mainly and a case where mainly gases and radicals are used, from changing the washing time cleaning experiment result, after introducing the particles, prior to heat treatment, the depth of the atomic concentration of particles becomes 1 E 1 8 atoms / cm 3 is 1 5 nm or less, in particular 1 0 nm
• the present invention has been made focusing on this point.
• the present inventors have developed a technology that can change the state of particles to be implanted into those mainly composed of ions and those mainly composed of gas and radicals, and are new findings. .
• impurities are introduced into a silicon substrate in the form of ions, gases and radicals. It has been explained. New knowledge was obtained by conducting experiments for the first time in cleaning and resist removal by changing the ratio of ions, gases and radicals to be introduced.
• the present inventors have proposed a plasma driving method in which the state of particles injected into a solid substrate from plasma is changed between a case where ions are mainly used and a case where gas and radicals are mainly used, and resist removal by oxygen plasma irradiation.
• the present inventors have found that, after introducing particles into the solid substrate, based on the experimental results of resist removal by oxygen plasma irradiation and the experimental results of cleaning using a mixed solution of sulfuric acid and hydrogen peroxide or hydrofluoric acid, By forming an oxide film on one main surface of the solid substrate into which impurities are introduced before heat treatment, it has been found that the dose in the resist removal and cleaning, and the annealing step can be reduced.
• the solid substrate after forming the deposit containing the particles is washed by contacting with a mixed solution of sulfuric acid and hydrogen peroxide before the heat treatment.
• the solid substrate that has been introduced with a very low energy is washed by contacting with a mixed solution of sulfuric acid and hydrogen peroxide solution.
• the energy so that the depth before heat treatment is 15 nm or less, especially 10 nm or less depends on the ion implantation method. For example, when boron is implanted in the drift mode, it is 30 V or more and 500 V or less. It is particularly desirable that the acceleration voltage be 200 V or less.
• the present inventors separately covered the inner wall of the process chamber with quartz, silicon, silicon nitride, a desired impurity and a nitride or oxide containing the desired impurity in an effort to improve the contamination level of the plasma doping apparatus.
• a plasma doping system By using a plasma doping system, the contamination level of the substrate after introducing the particles was successfully reduced.
• particles are introduced using a plasma doping apparatus in which the inner wall of the process chamber is covered with quartz, silicon, silicon nitride, a desired impurity, and a nitride or oxide containing the desired impurity.
• solid substrate contamination level is 1 E 1 0 atoms / cm 2 or less of the substrate after washed by contacting the cleaning solution before the heat treatment.
• the cleaning solution is desirably a mixed solution of sulfuric acid and hydrogen peroxide solution because the solid substrate can be cleaned without reducing particles introduced into the solid substrate to be processed such as a silicon substrate. Any other cleaning solution may be used as long as it forms an oxide film.
• the introduced particles can be maintained on the solid substrate without being washed away into the mixed solution of sulfuric acid and hydrogen peroxide.
• Particles are introduced using a plasma doping apparatus in which the inner wall of the process chamber is covered with quartz, silicon, silicon nitride, a desired impurity, and a nitride or oxide containing the desired impurity.
• the contamination level of the solid substrate is 1E10 atoms Zcm 2 or less, the effect on the dopant when the surface of the solid substrate is cleaned in the cleaning step can be reduced.
• the main purpose of the cleaning step is to clean the back surface of the solid substrate instead of the front surface of the solid substrate, it is not necessary to shorten the cleaning time or reduce the concentration of the solvent.
• the above purpose can be achieved by any device.
• the time for contacting the solid substrate with a mixed solution of sulfuric acid and hydrogen peroxide solution is preferably 10 minutes or less. This is because the dopant particles hardly decrease by washing for less than 10 minutes.
• hydrofluoric acid is often used in conventional cleaning methods, but the contact with hydrofluoric acid causes the particles of the dopant to be washed away quickly in a short time.
• the above-described method for cleaning a solid substrate is also effective as a method for manufacturing devices such as active elements such as semiconductors, liquid crystals and biochips, and passive elements such as resistors, coils and capacitors.
• FIG. 1 is a diagram showing an impurity introducing device used in one embodiment of the present invention
• FIG. 2 is a diagram showing a process flow for explaining one embodiment of the present invention
• FIG. FIG. 5 is a diagram showing a SIMS profile in the depth direction of boron measured using a secondary ion mass spectrometer (hereinafter, referred to as SIMS) when plasma doping is performed in the radical mode according to the present invention
• FIG. 4 shows a SIMS profile when plasma doping is performed with the ion mode according to the present invention
• FIG. 5 is a SIMS immediately after plasma doping with the gas / radical mode after the plasma irradiation amorphization according to the present invention.
• FIG. 6 is a diagram showing a profile
• FIG. 6 is a diagram showing a profile
• FIG. 6 is a diagram for explaining the influence of the introduction of impurities and the assembling method on sheet resistance according to an embodiment of the present invention
• FIG. 7 is an embodiment of the present invention.
• FIG. 8 is a diagram for explaining the effect of the method on the sheet resistance
• FIG. 8 is a diagram for explaining the effect of the cleaning time according to the present invention on the sheet resistance.
• Fig. 10 is a diagram for explaining the influence of the plasma doping method and the cleaning method according to the embodiment of the present invention on the sheet resistance
• Fig. 10 illustrates a device using the method for cleaning an object to be processed according to the present invention. Diagram showing the manufacturing process flow.
• FI G.11 AF I G.11 C is one of the devices manufactured by the process flow of FI G.10.
• FIG. 10 illustrates a device using the method for cleaning an object to be processed according to the present invention. Diagram showing the manufacturing process flow.
• FI G.11 AF I G.11 C is one of the devices manufactured by the process flow of FI
• FIG. 12 schematically shows a cross section
• FIG. 12 shows a process flow when plasma doping is performed in the ion mode according to the present invention
• FIG. 13 shows plasma doping in the gas-radical mode according to the present invention
• FIG. 15A-FIG. 15C shows a process flow when (1) is used. In FIG. 15A-FIG. 15C, the impurity layer (boron-introduced layer) introduced into the silicon substrate in the plasma doping according to the present invention is removed.
• FIG. 16 illustrates the mechanism that remains without intrusion.
• Fig. 16 shows the effect of the cleaning solution using SPM according to the present invention on sheet resistance and the surface of the silicon substrate after hydrofluoric acid according to the comparative example after SPM cleaning.
• Figure showing the effect of contact with F I G. 17 AF I G. 17 B is characteristic diagram for explaining the effect of the cleaning solution with APM according to the present invention is Ru applied to sheet one sheet resistance
• FI G. 18 is according to the present invention
• Jiporan B 2 FIG. 19 shows the relationship between the gas concentration of H 6) and the light absorption coefficient for light having a wavelength of 53 Onm on the silicon surface.
• FIG. 19 shows that the gas concentration of dipolane (B 2 H 6 ) according to the present invention was changed.
• FIG. 20 shows a process flow using an oxide film forming step before performing the cleaning step according to the present invention
• FIG. 21 shows a process flow using an oxide film forming step before performing the cleaning step according to the present invention
• FIG. 22 is a diagram showing a process flow using a plasma amorphization process and an oxide film process.
• FI G. 22 AFIG. 22 B shows an ion using hydrofluoric acid (HF) for comparison with the embodiment of the present invention.
• FIG. 4 is a diagram showing a cleaning process time and a change in sheet resistance when processing is performed in a gas / plasma mode, respectively.
• FIG. 1 shows the device 100 used in one embodiment of the present invention.
• the device 100 consists of a high-frequency power supply 1, a matching box 2, a coil and an antenna 3, a mass flow controller (MFC) 4 and 5, a turbo molecular pump 6, a conductance valve 7, a dry pump 8, a circuit board 9, a power supply 10, and a matching box 1.
• MFC mass flow controller
• the power supply 10 applies a bias power supply.
• An AC power supply with a frequency of 600 kHz was used.
• the numerical value of the acceleration voltage described in the present specification for the plasma doping is Vdc.
• Vdc is the average value of the bias voltage applied by AC.
• the difference between the peaks of the bias voltage is about twice Vdc.
• the object to be processed is a silicon substrate, which is one of semiconductor substrates, as an example.
• a silicon substrate which is one of semiconductor substrates, as an example.
• other solid substrates such as a compound semiconductor substrate, a strained silicon substrate, and an SOI substrate also correspond to the object of the present invention.
• FIG. 1 shows a state in which the silicon substrate 13 has been transported into the process chamber 15 and then set on the lower electrode 14.
• an inlet pipe 16 for the plasma irradiation amorphizing gas and an inlet pipe 17 for the diporane gas were separately provided.
• the plasma irradiation amorphization is a process of irradiating plasma to a main surface of a solid substrate, for example, a silicon substrate to make the surface of the silicon substrate 13 amorphous.
• the term “plasma irradiation amorphization” is used, but the amorphous state is not limited to plasma irradiation.
• Ge, Si ionized material may be ion-implanted to be amorphous.
• the plasma used for the plasma irradiation amorphization is a rare gas plasma such as helium, neon, argon, or xenon, a hydrogen plasma, or a plasma of a mixture thereof.
• plasma containing germanium (Ge) and silicon (Si) may be irradiated.
• Diporane gas is turned into plasma and used for B 2 H 6 plasma doping, or is introduced into the process chamber 15 as it is and used for gas doping.
• Jiporangasu B 4 H 10, B 5 H 9, B 5 Hu, B 6 H 10, B. It may be used gas hydrogen compound containing boron such as H 14.
• a hydrogen compound gas containing boron is more preferable because the etching rate of Si to be etched during plasma irradiation is small, and the process can be performed with almost no etching of the silicon substrate.
• contains boron such as BF 3 , B 2 F 4 Fluoride / compound gas may be used.
• B 2 C 1 4 it may be used gas chloride containing boron such as BC'l 3.
• BI 3 , BB r 3, B 2 ⁇ 3 , B 2 S 3 , or BN may be used.
• the gas flow introduced into the process chamber 15 can be controlled separately by the mass flow controllers 4 and 5. Further, although not shown in FIG. 1, a diluting gas introduction pipe and a mass flow controller are also provided around the process chamber 15 in order to change the dipolane gas dilution ratio. Helium gas was used as the dilution gas.
• FIG. 2 is a schematic diagram of a process flow for explaining an embodiment of the present invention.
• the silicon substrate 13 on the lower electrode 14 After placing the silicon substrate 13 on the lower electrode 14, performs the B 2 H 6 plasma doping S 23 by Jiporangasubura Zuma. Dipolane (B 2 H 6 ) gas diluted with helium (He) gas was used.
• B 2 H 6 plasma doping S 23 is simply referred to as “plasma doping S 23” to simplify the description.
• the plasma doping 23 was performed in two modes: an ion mode S23a and a gas / radical mode S23b.
• Plasma doping by ion mode S 23 a S 23 is a method of introducing impurities into which ions in plasma are mainly implanted into the silicon substrate 13.
• the plasma doping S 23 in the gas / radical mode S 23 b mainly introduces the gas and radicals in the plasma together with the ions into the silicon substrate 13, or attaches and deposits it on one main surface of the silicon substrate 13.
• Conditions bra Zuma doping S 23 is Jiporan in the range of 5% to 95% from the ratio (B 2 H 6 / He gas concentration) 0.025% / 99.975% diluted with helium, a high-frequency power source 1 The source power was varied from 1000 W to 1500 W, and the pressure was varied from 0.9 Pa to 2.5 Pa.
• typical ion mode S 2 3 a is, B 2 H a 6 / the He gas concentration of 0.025% / 99.975%, Sosupa Wa scratch 1 500 W, a pressure of 0. 9 P a This is the case.
• Typical gas radio Mode 23b is the case where the B 2 H 6 ZHe gas concentration is 5% Z95%, the source power is 1000W, and the pressure is 2.5Pa.
• boron is contained in gas and radicals, and is deposited on or adhered to the surface of the silicon substrate 13 or remains at a shallow portion of the silicon substrate 13 in a large proportion.
• boron implanted into the silicon substrate 13 as an ion. Since boron implanted as ions obtains energy from an electric field applied as a bias, boron is introduced from the outermost surface of one main surface of the silicon substrate 13 to a position deeper than the boron introduced as gas / radical.
• FIG. 3 shows a SIMS profile when plasma doping S23 was performed in the typical gas / radical mode 23b with a bias voltage of 100 V and a plasma doping time of 7 seconds.
• the features are that the boron concentration on the outermost surface of the silicon substrate 13 is high and the steepness of the profile is low.
• the steepness of the profile is the distance required for the boron concentration to decrease by an order of magnitude, and is usually expressed as the distance required for the boron concentration to decrease from 1 E 19 cm- 3 to 1 E18 cm- 3 .
• the reason why the steepness is low is that profiles having a boron concentration in the range of 1 E 18 cm- 3 to 1 E2 1 cm- 3 project downward from the lower boron concentration.
• the boron concentration on the outermost surface was about 8E22 cm- 3
• the steepness was 3 nm / dec.
• the proportion of boron implanted as ions is large, so that the proportion of boron implanted deep into the silicon substrate 13 is greater than in the gas radical mode S23b.
• the bias voltage is applied by an alternating current, and the depth of the impurity introduction layer in which each boron is implanted on one main surface of the silicon substrate 13 is determined according to the bias voltage at each moment.
• the proportion of boron implanted as ions is high Therefore, the ratio of deeply introduced boron to the whole introduced boron is higher than that in the gas-radical mode S 23 b.
• the mechanism described above is due to the fact that gas and radicals do not receive driving energy electromagnetically from the bias voltage and have low energy.
• the SIMS profile of boron immediately after performing plasma doping S23 in the ion mode S23a is such that the boron concentration on the surface of the silicon substrate 13 is lower than that in the gas radical mode 23b, and the boron concentration is lower.
• There the collision on the person who is profile boron concentration ranging from 1 E 18 cm- 3 of 1 E 21 cm- 3 decreases as below.
• FIG. 4 shows the SIMS profile when plasma doping S23 was performed in the typical ion mode S23a with a bias of 100 V and a plasma doping time of 30 seconds.
• the features are that the boron concentration on the outermost surface of the silicon substrate 13 is lower than that of the gas radical mode 23b, and that the profile has high steepness.
• the boron concentration on the outermost surface of the silicon substrate 13 was about 8E21 cm- 3 , and the steepness was 2 nm / dec.
• the plasma irradiation amorphization S22 was performed by irradiating rare gas plasma such as helium, neon, argon, and xenon. Hydrogen gas plasma was also used. These mixed plasmas may be used. Alternatively, a plasma containing Ge and Si may be irradiated.
• rare gas plasma such as helium, neon, argon, and xenon.
• Hydrogen gas plasma was also used. These mixed plasmas may be used.
• a plasma containing Ge and Si may be irradiated.
• the results when helium plasma is used are shown.
• the He gas concentration was 100%
• the source power of the high frequency power supply 1 was 1,500 W
• the pressure was 0.9 Pa
• the bias voltage was 150 V
• the plasma irradiation amorphization time was 7 seconds.
• plasma doping S23 was performed in the typical gas-radical mode 23b.
• the plasma irradiation amorphization S22 one main surface of the silicon substrate 13 is made amorphous, so that boron of gas and radicals is formed inside the silicon substrate 13 as compared with the case where the amorphization is not performed. Easy to penetrate.
• FIG. 5 shows a SIMS profile immediately after performing plasma doping S 23 in the typical gas-radical mode 23 b after plasma irradiation amorphization S 22. Its features are that the boron concentration on the outermost surface of the silicon substrate 13 is an intermediate value between the ion mode S 23 a and the gas radical mode 23 b, and that the profile ( ⁇ steepness is high) In FI G. 5, the boron concentration on the outermost surface is 4 E
• the boron adhering to the outermost surface of the silicon substrate 13 is reduced to the total boron introduced into the silicon substrate 13.
• the steepness is low because it accounts for so much.
• the ratio of boron implanted into the silicon substrate 13 to the total amount of boron introduced into the silicon substrate 13 increases, and boron adhering to the outermost surface of the silicon substrate 13 is increased. Is less or almost nonexistent, so the steepness is higher.
• the silicon substrate 13 was taken out from the process chamber 15. After that, assuring S24 or washing S25 was performed. In the flushing S24, the silicon substrate 13 was transported into one process chamber of an unillustrated asshing apparatus. As the asshing apparatus, an apparatus having a down-flow type plasma etching chamber was used. Thereafter, oxygen plasma was irradiated under the conditions of a high frequency power source (not shown) at 1800 W, 260 ° C, and 133 Pa. The oxygen plasma irradiation time was changed at three levels: 10 seconds, 25 seconds, and 60 seconds.
• a high frequency power source not shown
• SPM mixture solution of sulfuric acid and hydrogen peroxide, H 2 S0 4 and H 2 ⁇ 2 were mixed at a ratio of 6: 1, 4: 1 solution), 1% by HF (ultrapure water diluted HF), was used
• APM solution mixed at a ratio of NH 4 ⁇ _H and H 2 ⁇ 2 and H 2 0 1: 1: 5).
• SPM and APM were used at 80 ° C and HF at room temperature.
• the silicon substrate 13 was washed with SPM, HF, and APM, respectively.
• the washed silicon substrate 13 was rinsed with ultrapure water and dried. Further, for comparison, an experiment was conducted in which the process proceeds to the heat treatment S26 without performing the atthing S24 and the cleaning S25.
• the silicon substrate 13 was subjected to a heat treatment 26. Heat treatment 26 was performed at 1100 ° C for 3 minutes using a halogen lamp.
• This heat treatment (anneal) S 26 was selected under conditions that electrically activate the dopants, and thus R s (0) / R s ( t) well reflects the number of dopants left on the silicon substrate 31 by the cleaning S25.
• R s (0) is the sheet resistance when heat treatment S 26 is performed without performing the assuring S 24 and the cleaning S 25 after performing the plasma doping S 23.
• Rs (t) indicates a sheet resistance when the heat treatment S26 is performed after the plasma doping S23 has been performed and the etching S24 has been performed for t seconds or the cleaning S25 has been performed for t minutes.
• R s (0) Z Rs (t) is the ratio between R s (0) and Rs (t).
• FIG. 6 is a characteristic diagram for explaining the influence of the introduction of impurities and the asshing method on the sheet resistance according to one embodiment of the present invention, and is a diagram showing a change in the asshing time and the sheet resistance.
• Heat treatment S26 was performed at 110 T for 3 minutes.
• the vertical axis of FIG. 6 is the ratio between R s (0) and the sheet resistance R s (t) when heat treatment is performed after assembling.
• the horizontal axis is the time of atshing.
• the introduction of the impurities is performed when the plasma doping S 23 is performed in the typical gas-radical mode 23 b, and when the plasma doping S 23 is performed in the typical ion mode S 23 a. After performing plasma irradiation amorphization S22 with the use of the hemiplasma, plasma doping S23 was performed in the above-described typical gas-radical mode 23b.
• sheet resistance was reduced by about 30% by performing asking before heat treatment.
• the sheet resistance hardly changed with the change of the asching time.
• FIG. 7 is a characteristic diagram showing a relationship between cleaning time and sheet resistance according to one embodiment of the present invention. That is, it is a diagram showing a change in sheet resistance depending on a cleaning time.
• the vertical axis represents the ratio between R s (0) and the sheet resistance R s (t) when the substrate is contacted with SPM, cleaned, and then heat-treated before the heat treatment.
• the horizontal axis is the time of contact and cleaning with SPM.
• the plasma doping time was 60 seconds in the typical ion mode S23a.
• the acceleration voltage due to the bias was changed to three plasma potentials, 60 V and 100 V.
• a mixed solution of sulfuric acid and hydrogen peroxide having a mixing ratio of 6: 1 was used.
• the cleaning time by contacting with a mixed solution of sulfuric acid and hydrogen peroxide solution was changed from 30 seconds to '10 minutes. If the accelerating voltage is higher than 60 V, the sheet resistance hardly changes even if cleaning S25 is performed by contacting with a mixed solution of sulfuric acid and hydrogen peroxide before heat treatment S26.
• cleaning S25 reduced the sheet resistance to less than half. The reason is considered that the boron introduced into the silicon substrate 13 in the cleaning S25 was washed away from the silicon substrate 13.
• FIG. 8 is a characteristic diagram for explaining the limitation of the cleaning time according to one embodiment of the present invention.
• the cleaning time with a mixed solution of sulfuric acid and hydrogen peroxide was changed within a range of 30 minutes or less, and the difference in sheet resistance was examined. If the reduction in sheet resistance is to be secured to, for example, 90% or more of the case where cleaning is not performed, the cleaning time is preferably 20 minutes or less. A more preferred washing time is 10 minutes or less. If the cleaning time is 10 minutes or less, the sheet resistance can reliably maintain 90% or more of the value when cleaning was not performed. However, washing for 30 minutes is not preferable because the sheet resistance is reduced to 90% or less before washing.
• Table 1 shows the results obtained by measuring the contamination of one main surface (surface) of the silicon substrate 13 by flameless atomic absorption spectrometry when using a plasma doping apparatus in which the inner wall of the process champer was covered with quartz and when polon was dropped. The result. 52% of the area of the inner wall of the process chamber was covered with quartz. However, the portion covered with quartz is the plasma generation source side of the inner wall of the process chamber cut by the plane where the lower electrode 14 comes, that is, the coil and the antenna 3 side. The metal confinement is transferred to the silicon substrate 13 placed on the lower electrode 14 from the inner wall on the side of the plasma source rather than from the part on the exhaust side of the silicon substrate 13 on the inner wall of the process chamber. This is because the influence of metal contamination is great. Therefore, this corresponds to covering 84% of the area on the plasma source side cut by the plane where the lower electrode 14 on the inner wall of the process chamber comes.
• the plasma doping conditions were changed by two levels, and two wafers each were inspected. By changing the doping conditions, the dose amount and the depth at which the boron concentration becomes 1 E 18 cm “ 3 with as doped were changed.
• the expression as dopedj "was used for” after introducing impurities "or” After introducing the particles ”. It should be understood that the expressions below and Table 1 have the same meaning.
• the accelerating voltage was 60V and 100V, respectively.
• the doses were 7.5 E 14 cm- 2 and 5.2 E 14cnf 2 , respectively.
• the depths at which the concentration of Polon becomes 1 E 18 cm- 3 in as doped were 7.4 nm and 10 nm, respectively.
• F e when these, C r, N i, Cu , N a, a C a, K, Mg, contamination levels of A 1 in 1 E 10 at oms / cm 2 or less was. This is a very good result. This has made it possible to reduce the load on the substrate surface during cleaning to remove metal contamination and the like.
• the process chamber is made of a metal containing aluminum.
• the contamination level of aluminum has an allowable level as compared with the contamination of other metals in Table 1. high. Therefore, among the elements of Fe, Cr, Ni, Cu, Na, Ca, K, Mg, and Al, the aluminum confinement should not be overspecified.
• the area covered with quartz may be appropriately selected according to the specific apparatus and process conditions.
• an object to be processed for example,
• the semiconductor substrate silicon substrate
• the substrate can be set to a level of contamination necessary for maintaining the yield of semiconductor devices, and that the substrate can be cleaned without reducing introduced particles in the cleaning process.
• FIG. 9 is a characteristic diagram showing the relationship between the plasma doping method and the cleaning method according to one embodiment of the present invention, which affects the sheet resistance.
• the vertical axis represents the ratio between R s (0) and the sheet resistance R s (t) when the substrate is brought into contact with SPM before cleaning, washed, and then heat-treated.
• the horizontal axis represents the time of cleaning by contact with SPM.
• the plasma doping S23 has a plasma doping time of 30 seconds in the typical ion mode S23a and a plasma doping time of 7 seconds in the typical gas-radical mode S23b. In the case where the plasma doping time is set to 7 seconds in the typical gas-radical mode S 23 b after performing the plasma irradiation of the Made by kind.
• the acceleration voltage by the bias was changed to 60V and 100V.
• a mixed solution of sulfuric acid and hydrogen peroxide was used with a mixture ratio of sulfuric acid and hydrogen peroxide of 4: 1.
• Cleaning S25 was performed at 80 ° C for 5 minutes and 10 minutes, respectively. . For comparison, the sheet resistance when heat treatment was performed without washing was also measured.
• the sheet resistance did not increase by 10% or more even when the substrate was washed by contacting with a mixed solution of sulfuric acid and hydrogen peroxide before the heat treatment.
• the cleaning S25 reduced the sheet resistance.
• Amorphization by plasma irradiation After performing S22, the result of sheet resistance when plasma doping S23 was performed in gas-radical mode S23b was as follows: Plasma doping S23 in ion mode S23a The value was an intermediate value between the case where the plasma doping was performed and the case where the plasma doping S 23 was performed in the gas / radical mode S 23 b.
• FIG.10 shows a process flow according to Example 1 of the present invention.
• FIG. 11C is a cross-sectional view schematically showing a device formed on the silicon substrate 31, for example, an impurity introduction layer constituting a part of a transistor.
• the “silicon substrate 31” is substantially the same as the “silicon substrate 13” so far.
• the cross-sectional view shown in FIG. 11A-FIG. 11C shows an electronic device, such as a diode, a resistor, a capacitor or a coil, in a very simple and schematic manner. Please understand that.
• a silicon substrate 31 is prepared, a resist is formed on one main surface thereof, and a desired resist patterning S27 is performed by a well-known etching process.
• a desired resist patterning S27 is performed by a well-known etching process.
• the completed state at that time is shown in Fig. 11A.
• the typical ion mode S 2 3 a was subjected to plasma doping S 2 3 of Jipora emissions (B 2 H 6).
• the amorphous S 22 may be performed by irradiating a plasma of a rare gas, hydrogen, or a mixed gas thereof.
• the surface of the silicon substrate 31 is made amorphous by plasma irradiation amorphization. Exposure to the plasma used. Therefore, the surface of the silicon substrate 31 is made amorphous, or boron is introduced into one main surface of the silicon substrate 31, so that the impurity introduction layer 33 is formed as shown in FIG. 11B.
• oxygen plasma is exposed to the resist formed on one main surface of the silicon substrate 31 to perform asking.
• the impurity introduction layer 33 is exposed to oxygen plasma.
• the boron becomes silicon. It is not diffused outside the substrate 31 (so-called outward diffusion). Rather, the rate at which boron is lost to the outside of the silicon due to the ashes decreases, so that the sheet resistance after annealing can be reduced and the resist can be removed.
• the surface of the impurity layer 33 constituting the source and drain of the transistor is exposed on one main surface of the silicon substrate 31, for example. .
• one main surface of the silicon substrate 31 is exposed to SPM or APM for cleaning.
• the impurity introduction layer 33 of FIG. 11C is also exposed to SPM and APM.
• plasma doping S 23 is performed in the ion mode S 23 a and SPM is used, boron is not eroded or diffused out of the silicon substrate 31, and the sheet resistance is reduced. It is more desirable to use When the plasma doping S23 is performed in the ion mode S23a and the APM is used, boron is hardly eroded or diffused outside the silicon substrate 31, which is preferable.
• FIG. 12 shows a process flow according to Example 2 of the present invention.
• a resist is formed on the silicon substrate 31 (S31), and desired resist patterning S27 is performed.
• a resist pattern 30 and an opening 32 are formed on one main surface of the silicon substrate 31 by the processes S31 and S27.
• plasma doping S 23 is performed in the typical ion mode S 23 a.
• the amorphous S22 may be performed by irradiating a plasma of a rare gas, hydrogen, or a mixed gas thereof. Due to the plasma doping S 23 and the amorphization S 22, the opening 32 shown in FIG.
• the impurity introduction layer 33 is formed as shown in FIG.
• the rate of loss of boron outside the silicon substrate 31 is reduced by cleaning the silicon substrate 31, so that the sheet resistance after annealing can be reduced and the resist can be removed. it can.
• APM when the plasma doping S23 was performed in the ion mode S23a in the ion mode S23a, and when the plasma doping S23 was performed in the ion mode S23a after the plasma irradiation amorphous S22, boron was changed to silicon. The rate of loss outside the substrate 31 is small.
• the impurity introduction layer 33 is left on one main surface of the silicon substrate 31, as shown in FIG. 11C. After that, the surface of the silicon substrate 31 is exposed to SPM or APM for cleaning. At this time, the impurity introduction layer 33 of FIG. 11C is also exposed to SPM and APM.
• the sheet resistance after the FIG. 12 process flow is applied, and the resist patterning S 27, the resist removal S 28 a, and the cleaning S 25 a in the FIG. 12 process flow are omitted.
• the sheet resistance after the process flow of FIG. 12 was lower.
• APM is used for both the resist removal S 28 a or the cleaning 'S 25 a'
• the sheet resistance is the same as the resist patterning S 27 in the FIG. 12 process flow.
• the values were the same as those when resist removal S 28 a and cleaning S 25 a were omitted.
• the resist removal S 28 a and the cleaning S 25 a can be simultaneously performed as one process using the same solution. That is why the symbols S28a and S25a are surrounded by the symbol S53a (dotted line).
• one of the methods of forming the impurity-doped layer according to one embodiment of the present invention employs the process flow of FIG. 12 to remove the resist and to form the electronic device. It can be left on one main surface of the silicon substrate 31 which is a surface and inside thereof.
• resist removal S 28 a and cleaning S 25 a are more preferably performed by using SPM because the sheet resistance can be further reduced.
• FIG.13 shows a process flow according to the third embodiment.
• the main difference from Example 1 shown in FIG. 10 is that the mode of plasma doping S 23 is gas radical mode 23 b and the cleaning process is slightly different.
• Example 3 will be described with reference to FIGS. 13 and 11.
• a resist is formed on a silicon substrate 31 to form a desired resist pattern.
• This state is shown in FIG.
• the amorphous S22 is performed by irradiating a plasma of a rare gas, hydrogen, or a mixed gas thereof.
• plasma doping S 23 is performed in the typical gas-radical mode 23 b.
• one main surface (surface) of the silicon substrate 31 is exposed to plasma irradiated by plasma irradiation amorphization S22 or plasma during plasma doping S23. Therefore, after the silicon is made amorphous, boron is introduced into or penetrated into the silicon to form the impurity introduction layer 33 as in FIG. 1 IB.
• resist removal S28 oxygen plasma is exposed to the resist to perform asshing.
• the impurity introduction layer 33 introduced through the opening 32 shown in FIG. 11B is exposed to oxygen plasma.
• the plasma doping S23 is performed in the gas-radical mode 23b after performing the plasma irradiation amorphization S22, boron is not attached to one main surface of the silicon substrate 31. Boron easily penetrates inside. Therefore, the exposure of the silicon plasma 31 to the oxygen plasma causes the boron on one main surface of the silicon substrate 31 to fly away, so that the boron is less likely to be eaten and lost outside the silicon.
• the rate of loss of boron to the outside of the silicon substrate 31 is reduced by performing the asshing, so that the sheet resistance after the heat treatment (anneal) S26 is reduced and the resist can be removed.
• FIG. 11C After the step of resist removal S28, it becomes as shown in FIG. 11C. Thereafter, one main surface of the silicon substrate 31 is exposed to SPM for cleaning. At this time, the impurity introduction layer 33 of FIG. 11C is also exposed to SPM.
• the plasma doping S23 is performed in the gas 'radical mode' 23 and SPM is used, boron is not eaten out of the silicon substrate 31 and is not lost. Therefore, it is more preferable to use SPM.
• the resist can be removed, and boron can be left on one main surface of the silicon substrate 31 and the inside thereof.
• Gas la When plasma doping S23 is performed using dicalcium S23b, it is preferable to use SPM because the sheet resistance can be maintained without increasing.
• FIG. 14 shows another process flow according to the method for forming an impurity-doped layer of the present invention.
• An example of a device manufactured by the process flow of FIG. 14 is shown in FIG. 11A-FIG. 11C.
• Example 4 will be described with reference to FIG. 11A-FIG. 11C and FIG. 14.
• a silicon substrate 31 is prepared.
• a resist is formed (coated) on one main surface of the silicon substrate, and a predetermined resist patterning S27 is performed, so that a resist pattern 30 and an opening 32 are formed. This state is shown in FIG. 11A.
• amorphous S 22 may be performed by irradiating a plasma of a rare gas, hydrogen, or a mixed gas thereof. This Tossa,
• One main surface of the silicon substrate 31 is exposed to plasma irradiated by plasma irradiation and plasma doping S 22 by plasma amorphous at the opening 32 of the resist of FI G. 11 A. . Therefore, one main surface of the silicon substrate 31 becomes amorphous, or boron is introduced into one main surface of the silicon substrate 31, and as shown in FIG. 11B, an impurity introduction layer is formed in the opening 32. 3 3 is formed.
• the impurity introduction layer 33 is exposed to SPM.
• the plasma doping S 23 was performed in the gas radical mode S 23 b after the plasma doping S 23 was performed in the gas radical mode S 23 b and the plasma irradiation amorphization S 22 was performed.
• boron is less likely to be eaten by the outside of the silicon substrate 31 or to be lost due to outward diffusion. That is, in the case of SPM, boron is lost outside the silicon substrate 31 by performing the cleaning S25b. Since the ratio of the sheet resistance decreases, the sheet resistance after annealing can be reduced, and the resist can be removed.
• the sheet resistance after applying the process flow of FI G.14 was the same as that when resist patterning S27, resist removal S28b, and cleaning S25b were omitted. .
• the resist can be removed, and boron can leave a predetermined impurity amount on one main surface of the silicon substrate 31 and the inside thereof. Note that the resist removal S28b and the cleaning S25b can be simultaneously performed as one step using the same solution.
• FIG. 15A-FI G. 15C is that the boron introduced into the silicon substrate 31 in the plasma doping S23 is not removed from the silicon until the process after the heat treatment (anneal) by oxygen plasma or SPM cleaning.
• FIG. 4 is a diagram for explaining a mechanism.
• FIG. 15A is a diagram schematically showing a state immediately after boron 36 has been introduced into one main surface of the silicon substrate 31 by deposition, plasma doping or ion implantation.
• FI G. 15B is, for example, immediately after the cleaning S 25 b shown in FI G. 14 is performed
• FI G. 15C is, for example, Polon 36 immediately after performing the heat treatment S 26 shown in FI G. 14.
• FIG. 2 is a diagram schematically showing the behavior of
• the stage of SPM and oxygen plasma is an example, and the stage of HF and APM is a comparative example.
• the APM is an example when the mode of the plasma doping S23 is the ion mode S23a.
• performing the SPM cleaning S25b or performing asshing with oxygen plasma reduces the dose loss of boron introduced in the plasma doping S23. Reduction is a new finding.
• the SPM cleaning S25b and the ashes with oxygen plasma oxidize one main surface of the silicon substrate 31 to form an oxide film 29 on the surface of the impurity introduction layer.
• the boron 36 adhering or accumulating on the surface of the impurity introduction layer is not lost to the outside of the silicon substrate 31 during SPM cleaning S 25 b or oxygen plasma irradiation, but is lost to the oxide film 29. It is captured.
• the boron 36 adhered to one main surface of the silicon substrate 31 and introduced into the silicon substrate 31 is taken into the oxide film 29 formed by the SPM or oxygen plasma, and even during annealing, the silicon substrate 31 Protects from being lost by out-diffusion outside of 31.
• the silicon substrate 31 is etched during cleaning. Then, the boron 36 attached to one main surface of the silicon substrate 31 is washed away.
• the role of the boron 36 in the dose loss is intermediate between HF and SPM.
• FI G.16 is an experimental result illustrating the above mechanism.
• the plasma doping S 23 should be performed before the heat treatment S 26. It has been found that it is effective to form the oxide film 29 on one main surface of the silicon substrate 31.
• the oxide film 29 can be formed by irradiating oxygen plasma, contacting the SPM solution with the silicon substrate 31, applying an oxide film by CVD, or applying an oxide film by ion plating (Example 6).
• FIG. 17 is a characteristic diagram showing a change in sheet resistance with respect to a cleaning treatment time according to Example 6.
• Example 6 describes the effect of APM cleaning on the dose loss of boron.
• the silicon substrate 13 (31) was taken out of the process chamber 15.
• the plasma doping S23 was performed in two types, the typical ion mode S23a and the typical gas-radical mode 23b.
• the bias voltage was set to 60V and 100V.
• the silicon substrate 31 was subjected to APM cleaning S25a at 80 ° C.
• a PM includes a silicon substrate 31 after c washing with a solution in a mixing ratio of NH 4 OH and H 2 0 2 and H 2 ⁇ 1: 1: 5, rinsed with ultra-pure water and dried.
• experiments were also performed on a case where heat treatment was performed without performing AMP cleaning. The heat treatment was performed at 1100 ° C for 3 minutes using a halogen lamp.
• FIG. 17A and FIG. 17B are characteristic diagrams showing changes in sheet resistance depending on the cleaning processing time using APM.
• FIG. 17A shows a case where boron is introduced in the plasma doping S23 of the typical ion mode S23a.
• FIG. 17B shows a case in which boron is introduced in the typical gas-radical mode 23b plasma doping S23.
• the vertical axis shows the sheet resistance R when the silicon substrate doped with boron by plasma doping S 23 is heat-treated, respectively. It is the ratio of s (0) to the sheet resistance Rs (t) when the substrate is cleaned by contact with APM before heat treatment and then heat treated.
• the horizontal axis represents the cleaning time in contact with the APM, and the cleaning time was changed within a range of 10 minutes or less.
• Plasma in which 6 gases are extremely diluted with helium gas is used.
• the gas / radical mode 23b plasma having a high concentration of B 2 H 6 gas is used.
• the ion mode S 23 a amorphous formation occurs at the same time as the doping of boron 36, and boron as a gas or a radical component permeates into the silicon substrate 31 without adhering to one main surface of the silicon substrate 31.
• the gas-radical mode 23 b the formation of the amorphous phase does not proceed sufficiently, and the boron 36 easily adheres to one main surface of the silicon substrate 31.
• the difference between the ion mode S23a and the gas radical mode 23b is that the difference can be distinguished by comparing the light absorption coefficient of the amorphous layer on one main surface of the silicon base plate after plasma doping S23. explain in detail.
• a helicon wave plasma source was used as the plasma source.
• the gas used was a mixed gas of helium gas and diporane gas. The mixing ratio is from 95% helium gas to 5% diporane gas to 99% helium gas.
• the gas concentration was changed in the range of 0.025% at 975%.
• the silicon substrate 13 (31) was irradiated with plasma.
• the plasma irradiation conditions were as follows: source power of the high-frequency power supply 1 was 1500 W, pressure was 0.9 Pa, and plasma irradiation time was 7 seconds.
• the bias voltage was set at 60V. Thereafter, the plasma irradiation was stopped, the inside of the vacuum chamber 115 was evacuated to a vacuum, and purged with nitrogen gas, and the silicon substrate 13 (31) was taken out of the vacuum chamber 115.
• FI G. 18 is, 530 nm of B 2 H 6 mixture occupying the gas B 2 H 6 by changing the proportion of gas when performing bra Zuma doping S 23 B 2 H 6 gas concentration and the surface of the silicon substrate 31 Is the relationship of the light absorption coefficient for light of the wavelength The maximum light absorption coefficient was obtained when the plasma was made amorphous with He gas alone.
• the gas concentration of B 2 H 6 and He has not changed much optical absorption coefficient at 0. 1% Z99. 9% in the range of 0.025% Bruno 99.97 5% B 2 H 6 Roh He .
• the light absorption coefficient decreased as the B 2 H 6 gas concentration increased.
• B 2 optical absorption coefficient of the H 6 ZHE gas concentration amorphous layer was fabricated in a 5% / 95%, the 55% level when the B 2 H 6 ZHe gas concentration 0.1% / 99.9% And decreased to a level of 46% compared to the case where He was 100%.
• the light absorption coefficient is 6.3 times that of cSi.
• FIG. 19 shows a change in the thickness of the amorphous layer when plasma doping is performed by changing the B 2 H 6 / He gas concentration. Basically, it was found that an amorphous layer having the same level of thickness as when amorphous was formed with 100% He was formed.
• the B 2 H 6 ZHe gas concentration is most preferably set to 0.05% / 99.95% to 0.1% 99.9%.
• the B 2 H 6 gas concentration is increased beyond 0.1%, the light absorption coefficient decreases despite the same thickness of the amorphous layer because the degree of amorphousness decreases. It is thought that there is. In other words, the lower the concentration of B 2 H 6 gas and the higher the concentration of helium gas, the higher the degree to which the crystals fall apart. In order to form an amorphous layer having a high light absorption coefficient, it is more preferable that the B 2 H 6 gas concentration is 0.1% or less and the helium gas concentration is 99.9% or more.
• the amorphous layer having a high light absorption coefficient has a high degree of amorphousness, and gas-radical boron easily penetrates into the amorphous layer.
• an amorphous layer having a low light absorption coefficient is not sufficiently amorphous and is close to crystalline silicon. Therefore, it is difficult for gas and radical boron to penetrate, and the rate of adhesion to the surface is increased.
• the light absorption coefficient when plasma doping S23 was performed with the typical gas-radio force mode 23b at a bias voltage of 60V and plasma doping of 7 seconds was 8.4E4 cm- 1 . This was the same level as when the B 2 H 6 concentration of FI G. 18 was 5%. Also, even when the B 2 H 6 concentration was higher than 5%, the light absorption coefficient did not decrease significantly, and the decrease was saturated at 6E 4 cm ⁇ 1 .
• the boundary between the ion mode S 23a and the gas-radical mode 23b had a light absorption coefficient for light at 530 nm between 1.3 E5 cm- 1 and 6E4 cm- 1 . Since the change in the light absorption coefficient with respect to the change in the B 2 H 6 concentration is continuous, the boundary is the center of the light absorption coefficient of 1.3E 5 cm- 1 and 6E4 cm- 1 9.5 E4 cm- have been found to be 1 to become B 2 H 6 concentration. This B 2 H 6 concentration can be read from FIG. 18 as 0.7%. That is, when the B 2 H 6 concentration is 0.7% or less, the ion mode S 23a is used.
• FIG.20 relates to Example 7 of the present invention.
• This embodiment differs from the other embodiments in that an oxide film formation step S29 is provided after the plasma doping step S23. Other steps are almost the same as those of the other embodiments.
• one or more steps selected from resist removal and cleaning S30 are performed after the step of oxide film formation S29.
• the step of oxide film formation S29 may be performed simultaneously with one or more steps selected from resist removal and cleaning S30.
• An oxide film may be formed by CVD or ion plating. Thereafter, heat treatment S26 is performed. By doing so, the dose loss of boron 36 introduced by plasma doping S23 can be reduced.
• a step S31 for preparing the silicon substrate 31 a step S27 for performing resist patterning, a heat treatment S26, and the like are the same as those used in the other embodiments, and therefore detailed description is omitted.
• FIG. 21 shows the process flow of the eighth embodiment.
• a method selected from low energy ion implantation and gas doping may be used for impurity introduction.
• plasma irradiation amorphousization S22 is performed before the impurity introduction.
• gas doping it is preferable that boron contained in the gas is easily permeated into the silicon substrate 31 by performing plasma irradiation amorphization S22.
• gas doping is a process in which a silicon substrate 13 (31) is subjected to plasma irradiation amorphization S22 in a process chamber 15 and then the plasma irradiation is stopped, and then a gas containing boron such as dipolane is removed. This is a method for introducing impurities introduced into the interior of the process chamber 15.
• an oxide film 29 after the impurity is introduced there is a step of forming an oxide film 29 after the impurity is introduced.
• one or more steps selected from resist removal and cleaning S32 are performed.
• the oxide film formation S29 may be performed simultaneously with one or more steps selected from resist removal and cleaning S30.
• heat treatment S26 is performed. By performing such a series of treatments, dose loss of boron introduced with low energy can be reduced.
• the amorphization S 22 before the plasma doping may be performed by ion implantation instead of plasma irradiation as described above.
• G e Si ions may be ion-implanted to be amorphous.
• ions of a rare gas may be implanted.
• the same effect can be expected by using an ion shower.
• an apparatus having a plasma generation chamber, a mesh, and a table on which a silicon substrate is placed is used. The mesh is disposed between the plasma and the silicon substrate, and can apply a desired potential to the mesh.
• dispersed ion irradiation which is called an ion shower
• the amount of ion beam current applied to the silicon substrate surface is smaller than that of plasma doping that is directly exposed to plasma, but is orders of magnitude larger than that of ion implantation. Therefore, even a light element having a relatively small atomic weight can be efficiently made amorphous. For example, it is expected that elements with the smallest atomic weight, such as helium and hydrogen, can be made amorphous.
• FI G. 7, FI G. 8, FI G. 9 A, FI G. 9 B, FI G. 16 FI G. 17 A, FI G. 17 B, FI G. 22 A and FI G. G.22B shows the results of annealing (heat treatment) of the halogen (1100 ° C, 3 minutes) with the halogen lamp, but using the spike RT A at 1775 ° C. As for the dose loss ratio, the same result as that of anneal for 3 minutes at 110 ° C was obtained.
• the same effect can be obtained by replacing the plasma mode doping S 23 of the ion mode S 23 a with an ion shower.
• the ion shower here is basically the same as that used for the above-mentioned amorphization, and is different in that desired impurity particles are included in the plasma.
• this is a method in which plasma containing a desired impurity such as boron is guided to the silicon substrate surface through a mesh and irradiated with ions containing desired particles. Since ion mass separation is not performed, the amount of ion beam current containing the desired particles irradiated to the solid substrate is smaller than that of plasma doping directly exposed to plasma, but is orders of magnitude larger than that of ion implantation.
• impurities can be efficiently introduced. Mainly low due to the principle of impurity introduction in ion shower It is expected that the same effect as that of the plasma doping S23 in the ion mode S23a in which the ions of the energy are mainly introduced is obtained.
• Low-energy ion implantation includes gas cluster ion implantation using ion beam and molecular ion beam.
• Ion implantation using gas class ion beam means, for example, argon gas from a mixed gas of argon gas and B 2 H 6 gas.
• Gas clusters are formed by loosely bonding gas and boron, ionizing them, accelerating and transporting them by an electromagnetic field, and irradiating the silicon substrate with the gas clusters. The loose bonds break apart and the accelerating energy is allocated to each molecule of the gas cluster.
• the acceleration energy of one boron becomes very small.
• the acceleration energy of one boron is 10 / (n + m) k eV.
• the acceleration energy of one boron is about 100 eV, which is low energy.
• the ion implantation using a molecular ion beam accelerates, for example, B10Hx +, which is a decapoline ion. In this case, too, the molecules are dispersed on the silicon substrate surface, so the acceleration energy per boron becomes smaller. For example, if the accelerating voltage is 5 kV, one boron is equivalent to being implanted with a low energy of about 500 eV.
• ion implantation using a gas cluster-one ion beam or a molecular ion beam has a relatively high energy of at least kV or more, but the effective energy of a desired particle such as boron is high. Is small, resulting in a shallow implant.
• atomic concentration is 1 E 18 at 01 13 / particles (- becomes 111 3 become depth 1 5 nm or less, particularly 10 nm or less!
• the problems described in the present invention are manifested similarly to the case of the boron in the drift mode, and it can be easily estimated that the present embodiment can solve the problem.
• the silicon substrate 13 (31) was taken out from the process chamber 15.
• the plasma doping S23 was performed in two types, the typical ion mode S23a and the typical gas-radical mode 23b.
• the silicon substrate 13 (31) was subjected to HF cleaning at room temperature. Hydrofluoric acid with a concentration of 1% was used. The cleaned silicon substrate 13 (31) was rinsed with ultrapure water and dried. For comparison, an experiment was also conducted when heat treatment was performed without performing HF cleaning. The heat treatment was performed at 1100 ° C for 3 minutes using a halogen lamp.
• FIGS. 22A and 22B are characteristic diagrams showing the relationship between the cleaning time using HF and the sheet resistance.
• FIG.22A is a case where boron is introduced in the plasma doping S23 of the typical ion mode S23a.
• FIG.22B is a case where boron is introduced in the plasma doping S23 in the typical gas-radical mode 23b.
• the vertical axis shows the sheet resistance R s when heat-treating the silicon substrate 13 (13) doped with polon by plasma doping S23.
• the horizontal axis represents the time for cleaning by contact with HF, and the cleaning time was changed within a range of 10 minutes or less.
• the horizontal axis represents the cleaning time in contact with hydrofluoric acid, and the cleaning time was changed within a range of 10 minutes or less. Hydrofluoric acid with a concentration of 1% was used. The acceleration voltage by the bias was changed to plasma potential, 60V, 100V, and 200V.
• the value of (Rs (0) / Rs (t)) can be reduced by performing cleaning without depending on the doping acceleration voltage. That is, it was found that the sheet resistance after washing was increased. This is because the dopant (impurity) was washed away from the silicon substrate 31 by the cleaning. An increase in sheet resistance was also observed in so-called short-time cleaning with a cleaning time of 5 minutes or less. Based on these facts, the conventional cleaning recipe including the step of contacting with hydrofluoric acid even for a short time is based on the consideration that the sheet resistance is high. It causes rise.
• a solid substrate such as a silicon substrate into which a dopant (impurity) is introduced by plasma doping, low energy ion implantation, deposition on a surface such as deposition, or shallow implantation is used.
• a dopant impurity
• the substrate before heat treatment can be cleaned to a level necessary for maintaining the yield of semiconductor devices, and a method of cleaning the substrate without reducing the introduced particles in the cleaning process is provided. It is possible to do.
• the present invention is particularly applicable to a method and an apparatus for introducing impurities including cleaning a substrate after introducing particles into the substrate by plasma doping injection, deposition, etc., in a manufacturing process of a semiconductor, a liquid crystal, etc., and removing a resist. Can be.
• it since it can be used in the manufacturing method of devices such as resistors, coils, and capacitors, its industrial utility value is high.

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