WO2002000971A1 - Procede de fabrication d'une tranche epitaxiale en silicium et tranche epaxiale en silicium ainsi obtenue - Google Patents

Procede de fabrication d'une tranche epitaxiale en silicium et tranche epaxiale en silicium ainsi obtenue Download PDF

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Publication number
WO2002000971A1
WO2002000971A1 PCT/JP2001/005563 JP0105563W WO0200971A1 WO 2002000971 A1 WO2002000971 A1 WO 2002000971A1 JP 0105563 W JP0105563 W JP 0105563W WO 0200971 A1 WO0200971 A1 WO 0200971A1
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WIPO (PCT)
Prior art keywords
impurity concentration
concentration
dopant gas
transition region
phase growth
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PCT/JP2001/005563
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English (en)
Japanese (ja)
Inventor
Hitoshi Kabasawa
Yuji Okubo
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Shin Etsu Handotai Co Ltd
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Shin Etsu Handotai Co Ltd
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    • 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
    • H10P32/15—Diffusion of dopants within, into or out of semiconductor bodies or layers from the substrate during epitaxy, e.g. autodoping; Preventing or using autodoping
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B31/00—Diffusion or doping processes for single crystals or homogeneous polycrystalline material with defined structure; Apparatus therefor
    • C30B31/06—Diffusion or doping processes for single crystals or homogeneous polycrystalline material with defined structure; Apparatus therefor by contacting with diffusion material in the gaseous state

Definitions

  • the present invention relates to a method for producing a silicon wafer.
  • the silicon single crystal substrate and the silicon single crystal substrate are manufactured. It is important to maintain a constant impurity concentration profile in the transition region where the impurity concentration gradually changes at the interface with the epitaxial layer. In particular, it is important to maintain a constant impurity concentration profile in the transition region in the manufacture of silicon epitaxial wafers for power MOS FETs where the resistivity of the entire epitaxial layer affects the characteristics. .
  • the impurity concentration profile means the distribution of the impurity concentration in the silicon epitaxial wafer in the thickness direction of the wafer.
  • the impurities are once released into the vapor phase from the silicon single crystal substrate, the inner wall of the reactor, or a jig such as a susceptor, and then re-applied to the growing epitaxial layer.
  • the so-called auto-doping phenomenon which is taken in, occurs, and changes the impurity concentration profile of the transition region.
  • the influence of the silicon single crystal substrate becomes large.
  • the amount of auto-doping is expressed by the concentration of impurities taken into the epitaxial layer by the auto-doping phenomenon.
  • concentration of impurities taken into the epitaxial layer by the auto-doping phenomenon.
  • P phosphorus
  • a s arsenic
  • B boron
  • the auto-doping amount is reduced when forming an epitaxial layer on eight surfaces of a semiconductor.
  • the concentration of the dopant gas in the growth gas is increased stepwise and Z or continuously from the start of growth, and the growth is maintained at a constant level after the set concentration is reached.
  • An epitaxy growth method has been proposed.
  • the amount of auto-doping depends not only on the impurity concentration of the silicon single crystal substrate, the amount of etching of the silicon single crystal substrate performed before the epitaxial growth, the vapor growth temperature and the vapor growth rate, but also on the reactor at that time. Since it changes depending on the atmosphere, the impurity concentration profile is eventually affected by changes in the amount of auto-doping, and it has been difficult to maintain a constant impurity concentration profile.
  • An object of the present invention is to provide a method of manufacturing a silicon epitaxial layer that can maintain a constant impurity concentration profile in a transition region of an epitaxial layer. Disclosure of the invention
  • a method of manufacturing a silicon epitaxial wafer according to the present invention comprises a step of growing a silicon epitaxial wafer directly above a silicon single crystal substrate in a reaction furnace by vapor-phase growth.
  • a vapor phase growth step of a stable region for supplying a constant concentration of dopant gas into the reactor is a vapor phase growth step of a stable region for supplying a constant concentration of dopant gas into the reactor.
  • a dopant gas having a concentration that can obtain an impurity concentration higher than the autodoping amount is supplied into the reaction furnace.
  • a dopant gas having a concentration that can obtain an impurity concentration higher than the auto-doping amount is used in the transition region. It is intentionally supplied to intentionally shift the slope of the impurity concentration profile in the transition region to a higher concentration side.
  • the impurity concentration profile of the transition region is set in advance so that the impurity concentration becomes sufficiently higher than the expected amount of quat doping.
  • the impurity concentration in the epitaxial layer tends to be excessive due to the direct diffusion of impurities from the silicon single crystal substrate (outward diffusion described later). Therefore, the concentration of the dopant gas supplied into the reaction furnace is set to be lower than the concentration at which the impurity concentration of the epitaxial layer at the start of the vapor phase growth can be made the same as the impurity concentration of the silicon single crystal substrate. As a result, such a defect is avoided, and the impurity concentration profile in the transition region becomes more constant.
  • FIG. 1 shows the fabrication of a silicon epitaxial wafer with a transition region and a stable region.
  • FIG. 4 is a schematic diagram for explaining a relationship between a dopant gas supply concentration and an obtained impurity concentration profile of a wafer in comparison.
  • FIG. 2 is a schematic diagram showing an example of a non-doped impurity concentration profile.
  • FIG. 3 is a schematic diagram showing an example of an impurity concentration profile for determining a dopant gas supply concentration in a stable region.
  • FIG. 4 is a schematic diagram showing a problem that occurs in the impurity concentration profile when the supply pipe is not purged before the supply of the dopant gas.
  • FIG. 5 is a schematic diagram showing an example of an impurity concentration profile of a silicon epitaxial layer 18 having a transition region and a stable region obtained by the method of the present invention.
  • FIG. 6 is a schematic diagram showing a relationship between a flow rate of a dopant gas and an impurity concentration in a stable region.
  • FIG. 7 is a diagram schematically illustrating the relationship between the supply concentration of a dopant gas and the amount of auto-doping when forming a transition region.
  • FIG. 8 is a diagram conceptually showing an example of a silicon epitaxy wafer manufacturing apparatus. BEST MODE FOR CARRYING OUT THE INVENTION
  • FIG. 1 is a schematic representation of the setting of the dopant gas supply concentration according to the present invention (upper figure) and the resulting impurity concentration profile in the silicon epitaxial wafer (lower figure). is there.
  • the impurity concentration profiles shown below are all semilogarithmic graphs, and the impurity concentration shown on the vertical axis is a logarithmic value.
  • FIG. 8 schematically shows an example of an apparatus used for manufacturing a silicon epitaxial wafer, in which a silicon single crystal substrate W is held in a susceptor in a reaction furnace 1 and heated to a predetermined temperature by a heater 2. Heat. Then, by flowing a predetermined ratio of a source gas and a dopant gas together with a carrier gas into the reaction furnace 1 through the gas supply pipe 3, the silicon single crystal substrate W is formed on the main surface of the silicon single crystal substrate W. Silicon epis of the same conductivity type The epitaxial layer is grown by vapor phase to obtain a silicon epitaxial wafer.
  • a dopant gas having a concentration that can obtain an impurity concentration higher than the autodoping amount is supplied.
  • the auto-doping amount varies depending on the atmosphere in the reaction furnace 1 at that time.Before starting the production of Silicon Epitaxial A-8, the following preliminary investigation test is performed to use it for the production. Check the atmosphere inside the reactor.
  • an epitaxial layer having a desired thickness is vapor-phase grown directly on a silicon single crystal substrate without supplying a dopant gas (non-doped). Then, a non-doped impurity concentration profile as shown in FIG. 2 (hereinafter simply referred to as a non-doped profile) is obtained.
  • the non-doped profile epitaxial layer is composed of an outward diffusion dominant region and an autodoping dominant region.
  • outward diffusion refers to the direct diffusion of impurities from a silicon single crystal substrate into an epitaxial layer.
  • the amount of outward diffusion mainly depends on the shape of the impurity concentration profile. To decide.
  • the amount of auto-doping controlled region the amount of auto-doping mainly determines the shape of the impurity concentration profile.
  • the out-diffusion-dominated region appears on the profile as a linear section in which the impurity concentration is reduced at a substantially constant gradient from the start of vapor phase growth.
  • the auto-doping dominant region appears as a flared curved region following the out-diffusion-dominated region in a form deviating from the extension of the out-diffusion-dominated region to the high concentration side.
  • the outer diffusion dominating region and the autodoping dominant region can be approximately determined by drawing an extension 1 of the outer diffusion dominating region on the impurity concentration profile.
  • the region where extension line 1 and the impurity concentration profile overlap is the out-diffusion region, and the boundary point where the impurity concentration profile deviates from extension line 1 to the higher concentration side is P, and the region after point P.
  • Auto-doping It is a dominant area.
  • D of the impurity concentration. / 2 is Contribution from outdiffusion, residual D. / 2 can be considered as a contribution from the autodoping phenomenon. That is, it can be estimated that the impurity concentration due to the auto-doping phenomenon at the point P is D 0/2 .
  • the supply concentration of the dopant gas required to form a desired impurity concentration as a stable region is determined. Specifically, by changing the flow rate of the dopant gas to be supplied and the flow rate of hydrogen for diluting the dopant gas, the supply concentration of the dopant gas is varied to produce various silicon epitaxial wafers, The average impurity concentration in each stable region is measured.
  • FIG. 3 is an example of an impurity concentration profile having a stable region.
  • Dt and Ds are the impurity concentrations in the stable region of the silicon single crystal substrate and the epitaxial layer, respectively.
  • a concentration-flow rate relationship curve as shown in FIG. 6 is obtained.
  • the purpose is to determine the impurity concentration in the stable region corresponding to the change in the supply concentration of the dopant gas. There is no. However, naturally, the obtained impurity concentration profile (Fig. 3) is the same as the conventional one, and the profile of the transition region varies greatly depending on the amount of auto-doping.
  • the supply concentration of the dopant gas at the starting point ( ⁇ ') of the transition region is calculated as shown in Fig. 7 (lower figure). Determined using a single flow rate relationship curve.
  • the dopant gas supply concentration at M ′ is higher than the estimated autodoping amount, and is equal to or lower than the impurity concentration Dt of the silicon single crystal substrate, for example, a value obtained by subtracting a predetermined amount ⁇ from Dt ( Set to a concentration C (D t -hi) that can be adjusted to D t -hi.
  • the doping concentration of the dopant gas is set to a concentration that can be higher than the impurity concentration Dt of the silicon single crystal substrate, the amount of impurities adhering to the inner wall of the reaction furnace or a jig such as a susceptor is reduced. From the substrate This is not preferable because the amount of impurities becomes larger than the outward diffusion amount and the amount of auto-doping is unnecessarily increased.
  • purging means flowing a dopant gas without supplying it into the reactor 1. If purging is not performed, the gas flow rate will not be stable before the dopant gas flow control device changes from the closed state to the set value, and an abnormal impurity concentration profile as shown in Fig. 4 may occur. Because there is.
  • a purge pipe 6 for flowing the raw material gas and the dopant gas in a form bypassing the reactor 1 and a supply valve for switching between supply and purge in the furnace are shown. 4 and a purge valve 5 are provided.
  • the impurity concentration of that is, the dopant gas to be higher than O over preparative doping amount of P in terms of non-doped profile described above The supply concentration is set in advance.
  • the impurity concentration at point P is 2 XD. Can be set so that This is, at point P, already D. Since the impurity concentration equivalent to is supplied by the outward diffusion and the auto-doping phenomenon, D. This means supplying a concentration C (D 0 ) that can obtain only impurity concentration as dopant gas.
  • the estimated autodoping amount at point P is D. Therefore, setting the supply concentration of the dopant gas to C (D 0 ) means setting the concentration higher than the auto-doping amount.
  • the dopant gas is supplied while always supplying a dopant gas having an impurity concentration higher than the autodoping amount.
  • the supply concentration of the punt gas is changed. If the supply concentration of the dopant gas is gradually reduced linearly or stepwise, for example, as shown in FIG. An impurity concentration profile is obtained.
  • the vapor deposition of the transition region when you grow thickness x p rest of Epitakisharu layer corresponding to the boundary point P, at least, sufficiently higher than the auto-doping amount of impurities
  • the concentration of impurities is indicated by the broken line in Fig. 7 (upper figure), when the dopant supply amount is not corrected to exceed the auto-doping amount.
  • the tilt amount shifts to the higher density side than the density profile. As a result, even if the amount of auto-doping changes, the amount falls within the allowable change range of the inclined impurity concentration profile. Further, as shown in FIG.
  • the impurity concentration profile of the transition region has two or more sections in which the logarithm of the impurity concentration gradually decreases in the growth direction of the epitaxial layer. This is because a dopant gas having a concentration that can obtain an impurity concentration sufficiently higher than the photodoping amount after the boundary point P is supplied, and the supply concentration of the dopant gas is gradually or linearly increased. It can be formed by reducing to
  • n + type impurity concentration: 3 ⁇ 10 19 cm 3
  • a s arsenic
  • an n-type epitaxial layer doped with phosphorus (P) as an impurity at a lower concentration than the substrate as follows.
  • a silicon epitaxial wafer was manufactured by vapor-phase growth on a silicon single crystal substrate. That is, the target impurity concentration at the start point of the transition region (point M in FIG. 7 (upper figure)) is lower than the impurity concentration Dt (3 ⁇ 10 19 Zcm 3 ) of the silicon single crystal substrate. And impurity concentration D at point P.
  • the supply concentration of the dopant gas was adjusted so as to obtain a higher impurity concentration of 5 ⁇ 10 17 (Z cm 3 ), and the dopant gas was purged at the set value.
  • a vapor phase growth process was started by introducing the dopant gas into the reaction furnace together with the source gas with the above supply concentration as an initial value.
  • the impurity concentration is always higher than the expected amount of auto doubling, and the impurity concentration added at the position corresponding to the point P is 1 ⁇ 10 17 Z cm 3
  • the supply concentration of the dopant gas was adjusted so that Then, the supply amount of the dopant gas was gradually reduced linearly.
  • a dopant gas whose concentration is adjusted so that the impurity concentration becomes 1 ⁇ 10 15 Z cm 3 is supplied at a constant supply concentration, and the n-type gas is supplied.
  • a 15 m vapor phase was grown on the epitaxial layer.
  • a silicon epitaxial wafer having a total thickness of 20 m of an epitaxial layer formed on a silicon single crystal substrate was obtained.
  • the vapor growth temperature and furnace pressure are the same as in the preliminary investigation.
  • the impurity concentration profile of the silicon epitaxial wafer thus obtained was measured, a profile as shown in FIG. 5 was obtained.
  • the thickness of the transition region was about 5 ⁇ m, the impurity concentration in the P point 1.
  • 5 X 1 0 17 atoms / cm 3 the impurity concentration in the stable region is met 1 X 1 0 15 atoms Z cm 3 was.
  • a linear gradient section where the logarithmic value of the dopant concentration decreases almost linearly was formed between the point P and the stable region.
  • the logarithm of the impurity concentration also decreases linearly in the section corresponding to the outward diffusion control region from the growth start point of the epitaxial layer to point P.
  • the impurity concentration profile of the transition region in the example has two sections where the logarithmic value of the impurity concentration decreases linearly in the growth direction of the epitaxial layer.
  • the specific mode of changing the supply concentration of the dopant gas in the vapor phase growth step of the transition region is not limited to the mode of monotonically decreasing the concentration as described above, but may be a concentration at which an impurity concentration higher than the auto-doping amount can be obtained.
  • the impurity concentration profile in the transition region may be increased in order to obtain a desired shape, or a period in which the supply concentration is kept constant may be provided in the middle. It is possible to appropriately combine two or more of the fixed holdings.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Crystals, And After-Treatments Of Crystals (AREA)
  • Chemical Vapour Deposition (AREA)

Abstract

Afin de maintenir constant le profil de la concentration d'impuretés dans une zone de transition pouvant être soumise aux effets d'un phénomène d'auto-dopage, un gaz dopant dont la concentration est telle que la concentration d'impuretés est supérieure à la quantité d'auto-dopage est chargé dans la zone de transition de manière à transférer le gradient du profil de la concentration d'impuretés de la zone de transition côté concentration plus élevée. En d'autres termes, le profil de la concentration d'impuretés de la zone de transition est présélectionné de telle sorte que ladite concentration soit suffisamment plus élevée que la quantité d'auto-dopage estimée. La quantité d'auto-dopage est limitée, même si elle est modifiée, à une gamme de modification acceptable du gradient du profil de la concentration d'impuretés, de sorte qu'un dispositif semi-conducteur fabriqué à partir d'une tranche épitaxiale en silicium ne soient pas soumis aux effets d'un phénomène d'auto-dopage.
PCT/JP2001/005563 2000-06-29 2001-06-27 Procede de fabrication d'une tranche epitaxiale en silicium et tranche epaxiale en silicium ainsi obtenue Ceased WO2002000971A1 (fr)

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JP2000195880A JP3791667B2 (ja) 2000-06-29 2000-06-29 シリコンエピタキシャルウェーハの製造方法
JP2000-195880 2000-06-29

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Publication number Priority date Publication date Assignee Title
JP5227670B2 (ja) * 2008-06-12 2013-07-03 Ｓｕｍｃｏ Ｔｅｃｈｘｉｖ株式会社 エピタキシャルウェーハの製造方法
WO2011125305A1 (fr) * 2010-04-08 2011-10-13 信越半導体株式会社 Tranche épitaxiale de silicium, son procédé de fabrication, et procédé de production d'un élément semi-conducteur ou d'un circuit intégré
JP6330718B2 (ja) * 2015-04-17 2018-05-30 信越半導体株式会社 エピタキシャルウェーハの製造方法
JP6332698B2 (ja) * 2015-07-24 2018-05-30 信越半導体株式会社 エピタキシャルウェーハの製造方法
CN113322512B (zh) * 2021-08-03 2021-12-17 南京国盛电子有限公司 一种提高外延片过渡区一致性的工艺方法

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0684809A (ja) * 1992-09-04 1994-03-25 Rohm Co Ltd エピタキシャル層の形成法
JPH0817737A (ja) * 1994-07-04 1996-01-19 Komatsu Electron Metals Co Ltd エピタキシャル成長法及びエピタキシャル成長基板
JP2000191395A (ja) * 1998-12-25 2000-07-11 Komatsu Electronic Metals Co Ltd 半導体ウェ―ハの薄膜形成方法および半導体ウェ―ハ

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0684809A (ja) * 1992-09-04 1994-03-25 Rohm Co Ltd エピタキシャル層の形成法
JPH0817737A (ja) * 1994-07-04 1996-01-19 Komatsu Electron Metals Co Ltd エピタキシャル成長法及びエピタキシャル成長基板
JP2000191395A (ja) * 1998-12-25 2000-07-11 Komatsu Electronic Metals Co Ltd 半導体ウェ―ハの薄膜形成方法および半導体ウェ―ハ

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TW507025B (en) 2002-10-21
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