• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    A method is disclosed for the production of n-doped silicon single crystals, each having a dish-shaped specific electrical resistance profile in a radial direction about a central axis of the crystal. A silicon single crystal is exposed to a pattern of radiation with neutrons according to the reaction 30Si (n, gamma ) 31Si beta --> 31P. The neutron radiation causes a weaker doping concentration in marginal regions of the crystals due to the production of fewer phosphorus atoms. Either p-conductive silicon crystals or n-conductive silicon crystals may be utilized as an initial material for exposure to the neutron radiation.
    公开号:SU747403A3
    申请号:SU762419003
    申请日:1976-11-15
    公开日:1980-07-23
    发明作者:Хаас Эрнст；Платцедер Карл；Райнфельдер Ханс-Эрих；Шнеллер Манфред
    申请人:Сименс Аг (Фирма)；
    IPC主号:
    专利说明:

    (54) METHOD FOR OBTAINING SILICON A-TYPE
    one
    The invention relates to a method for producing silicon of a conic with a plate-shaped resistivity profile (p) in the radial direction by irradiation with thermal neutrons.
    In general, there is a desire to obtain silicon single crystal rods for the manufacture of semiconductor elements from them, in which in their radial direction there are very homogeneous resistance values.
    For the manufacture of special semiconductor elements, such as large-area locking power thyristors, in which the avalanche sample is sought to move from the edge of the disk to its middle, it is desirable to have silicon crystals that, with a uniform J3 in the middle of the disk, have an increase in electrical resistivity in the edge area / - (disc shape - profile of the distribution of the resistivity of the silicon crystal disk). This means that the distribution of the doping impurity in the radial direction in the marginal zones of the silicon crystal is lower in terms of: the ratio with the middle zones. Conductivity
    It is known from Article 1 that silicon crystals with homogeneous conductivity can be produced by irradiating with thermal neutrons, and the natural isotope 30s {present in silicon} passes when a thermal neutron is received and f-radiation is returned to an unstable isotope 31 which is irradiated with. period
    10 half-life of 2.62 hours goes into a stable phosphorus isotope 31p. With the so-called radiogenic silicon doping by the reaction
    30g. (n, y) - 3lgi - 31r
    15
    There is the following simple interdependence (assuming complete attenuation and neglecting burnout
    ae
    because of its insignificance):
    thirty,
    si Wed 2-O-10 - f t,
    where Cf is the concentration of phosphorus in
    atom / cm, Ф - thermal neutroi flux in
    25
    neutron / cm, sec .; t is the irradiation time in seconds. The purpose of the invention is to obtain a plate resistivity profile in the radial direction.
    30 crystals. with jToO aim, it was proposed that the crystal, in the process of irradiating, rotate the twist of its longitudinal axis and direct a more intense or less intense neutron flux into its center than on its edge. The intensity of the neutron flux directed to the crystal is controlled by varying the width of the diaphragm splines or using the target of the desired profile or detecting the crystal in the reactor zone with a non-linear neutron flux gradient. The invention is illustrated in the drawings, where FIG. 1-9 depict examples of the behavior of a silicon crystal in a neutron field. According to FIG. 1, during neutron irradiation, a slit-shaped diaphragm 2 is installed in front of the vertically fixed silicon crystal rod 2. and the silicon crystal 1 is rotated around its longitudinal axis in the direction of the arrow 3. This uses a movable diaphragm 2 made of cadmium thick 1 mm of borate glass. When the silicon crystal 1 rotates, the middle parts 4 are constantly in the zone of a parallel or slightly divergent neutron beam 5. The edge zones of the silicon crystal b are irradiated less because they are only affected by scattered and diffused neutrons. As can be seen from FIG. 1, increasing the resistance of silicon. In this case, the profile for hanging on the set width of the diaphragm. When using a cadmium diaphragm with a thickness of 1 mm, there is an almost complete absorption of neutrons. In the second case, as shown in FIG. 2, in accordance with an example, the irradiation of a silicon crystal 1 is carried out in a reactor, for example, in a Swimming-Poole (pool) reactor, which in FIG. not shown Irradiation occurs in the zone with flow gradients when the silicon 1 crystal rotates around its longitudinal axis in the direction of arrow 3. A part of the neutron beam 5, which travels a longer path in water 7, loses its intensity. As a result of rotation, as in the case of FIG. 1, a rotationally symmetric p-profile is obtained with a rise in the outer zones, shown in FIG. 3. FIG. Figure 4 shows the neutron flux characteristic in a silicon 1 crystal in a neutron field with nonlinear flux gradients. In this case, the distance of the silicon crystal 1 from the surface of the rod combustion in the CM- axis is plotted along the abscissa axis, and the relative concentration of thermal neutrons is along the ordinate axis. In another variant of the subject of the image, the shadow is also provided for the floor. The doctrine of the p-profile by means of a controlled gyPO - yy ray of the dogogype ,. (/ E fast N (YTROHON, on the silicon crystal and the target. At that, the target should be performed as a retarder. P-PrOfil receive thanks to the fact that due to the geometry of the target, less sticking is created on the edge For example, paraffin, graphite, or water. This variant is shown in Fig. 5, where the silicon crystal 1 being irradiated is placed in tube 8 and on its outer surface is covered, at least partially, with a neutron-absorbing material, and each of its end sides closed, at least partially, absorbing neutrons with disks 9 and 10, which have holes 11 and 12 in the middle, respectively, of the desired) profile. The material absorbing neutrons can be borate glass, boron carbide, boron nitride, cadmium oxide and cadmium sheet and / or artificial materials, such as , polyethylene with the addition of a gadolinium compound or silicone rubber, which are applied to the respective surface. Between the neutron source 6 and the absorbing disks 9 and 10 are placed diaphragm tubes 13 and 14 made of cadigi or borate glass, matched by hole size of absorbing discs. The execution of the J profile depends on the different lengths of the diaphragm tubes 13 and 14, on their internal diameter and on the different thickness of the absorbing material. This device (see Fig. 5) for doping with phosphorus by neutron irradiation is mounted in a reactor, which is not shown in the figure. Depicted in FIG. 5, the device may be configured as shown in FIG. 6. Here, for irradiating silicon disks 15 ,, (and only one chamber is shown filled in the figure), tube 8 with non-auger elements FOR1 of silicon crystal disks, which can be made of neutron absorbing material in the form of rings 16, is used from two ends. These elements are placed on the inner surface of the tube 8 at a corresponding distance from each other. The material used may have a greater absorption coefficient than the tube material. By changing the absorbing 5 parts, the production of phosphorus atoms can be additionally changed. With an absorption thickness of, for example, 1 mm (cadmium sheet), the thermal portion of the neutron flux can be reduced to a value below 1/10,000. FIG. Figure 7 shows another variant of the invented method in which the absorbing coating 17 is deposited on the surface of silicon and which can evenly move along the silicon crystal rod 1 in direction 18. At the same time, the J) profile can vary along the length of the absorbing surface. An absorbent coating 17, consisting, for example, of cadmium casting with a thickness of 1 mm, is moved along the length of a silicon crystal rod 1 in m irradiation in such a way that any portion of the surface of the silicon crystal rod 1 coating remains at the same time as the closed absorbing coating. Due to the fact that each edge region of silicon crystal 1, with uniform movement of the absorbing coating 17 along the silicon crystal rod 1, has equal irradiation conditions, the desired Poppet P-profile is created (see Fig. 3). You can also move during the neutron irradiation instead of the absorbing coating. 17 silicon crystal rod 1. The invention is further explained below with reference to FIG. 8 and 9 and of the example, where in FIG. 8 shows in schematic form a device in accordance with the subject invention, consisting of a system with two diaphragms, in front of a silicon crystal rod, and FIG. 9 shows a device of several systems of diaphragms, mounted from the outer surface of the irradiated rod of a silicon crystal 1. From FIG. 8 it can be seen that three zones can be distinguished in the irradiated silicon crystal rod 1 (zone 1, the angle of visibility is limited solely by the diaphragm 19; zone 2, the angle is limited by the edge of the diaphragm 19 and the diaphragm 20; zone 3, the restriction is only by the diaphragm 20 ). By proposing an isotropic neutron distribution in space 21, the ratio of the neutron flux density at (X, Y) (in the silicon crystal rod 1) to the neutron flux density in space 21 is determined by the viewing angle L / 25Г. The calculation of the three possible cases should be carried out separately. Zone 1:
    权利要求:
    Claims (4)
    [1]
    takes place under the condition of a full wage. When translated into polar (1.1 x g r y g gb ((d i-rsinp; HS tan g 2d r & mP d-b Zone 3: similar to 1-ccd 2bz (dg.sin4)), rstn P -d2-b Zone 2. (((2 (X -anrtan; s.CHG2T - t «nt (j I AtsAFragm d arcs4o | n - arctan y -v. arclan (,) (,),)) (.dQ (X-ÜLSJr-x) (ytd,) (y4d2; 4 (.) tX (.da-ol.) b, (d, + dj) x (b, -bj + ol, d, -b , b, carc-tan SinPCbi-tb2) trcoS-P () + b-, d2.b; di r rsinP () + rcoSP (b, -bj,) d ,, b The desired doped f (G) profile is radiated by averaging all angles (- rotation of a silicon crystal 1). ZK f (g) J (. (g, h) acz. A digital calculation was performed for a different shape of the slits and a crystal core with a radius of 25 mm. In this case, two identical systems were used. Obtaining an absolute value of n: 5, doping concentrations can be poured by replacing the flux density of neutrons F in the usual equation by f (g). In addition, it is necessary to take into account that 100% reward material of the diaphragm was taken into account in the calculation. No, that is.% of all neutrons passes through the diffraction material, then this means decreasing the constant function to Y by numerical profiles m. In the equation for tivation, in this section F should be replaced in 100th. f f (g) TosG Numerical example: For the reaction 30g | {nS) Tukhani 3lgi and neglecting the benefits of 30gj, (since it is very significant), the next is Avg Wed 2-05-10. t. F 100 x I where Cf is the concentration of phosphorus in atom / cm2; F is the neutron warm neutron flux / cm sec, I t is the irradiation time in seconds X is the transmittance of the blend material in%; f (g) is the screening factor (see text). Take for example: F a 5 102. t 10 half-open aperture 19: b., 10 half-open aperture 20: b 5 distance from the middle of the silicon crystal rod to 19: d, 30 dpi, 30 from the middle of the silicon crystal rod to the aperture 320: dg 25 For tea absorption coefficient then: radius (m) concentration of phosphorus. atom, cm и and. This would correspond to a decrease in doping by 35% from the center to the edge by selecting other diaphragm systems or other diaphragm material (with less absorption). This value can be easily changed in wide mastabas. Besides; it is not excluded that homogeneous irradiation of a silicon crystal with neutrons is possible, followed by additional irradiation. Claim 1. A method of producing silicon of n-type conductance by irradiating a single crystal with a thermal neutron flux, characterized in that, in order to obtain a plate-shaped resistivity profile in the radial direction of the crystal, the radiation is rotated around its longitudinal axis and directed in its direction the middle is a more intense or less intense neutron flux than on its edge.
    [2]
    2. A method according to claim 1, characterized in that the intensity of the neutron flux directed to the crystal is adjusted by changing the width of the diaphragm splines,
    [3]
    3. Method of pop, 1, characterized in that the intensity of the neutron flux directed to the crystal is changed by using the target of the desired profile.
    [4]
    4. Method according to claim 1, characterized in that the crystal is irradiated in the reactor zone with a nonlinear neutron flux gradient. Sources of information taken into account in the examination 1, Oh, Electpochem, Zoe. 1961, 108, p. 171-179 (prototype).
    My / y- ff -y-
    I)
    nineteen
    20
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    引用文献:
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    US3255050A|1962-03-23|1966-06-07|Carl N Klahr|Fabrication of semiconductor devices by transmutation doping|
    DE2433991A1|1974-07-15|1976-02-05|Siemens Ag|METHOD OF DOPING A SEMICONDUCTOR LAYER|DE2753488C2|1977-12-01|1986-06-19|Wacker-Chemitronic Gesellschaft für Elektronik-Grundstoffe mbH, 8263 Burghausen|Process for the production of n-doped silicon by means of neutron irradiation|
    US4348351A|1980-04-21|1982-09-07|Monsanto Company|Method for producing neutron doped silicon having controlled dopant variation|
    JPS5958866A|1982-09-28|1984-04-04|Mitsubishi Electric Corp|Thyristor|
    DE3511363A1|1985-03-28|1986-10-09|Siemens AG, 1000 Berlin und 8000 München|METHOD FOR PRODUCING AREAS WITH ADJUSTABLE, SAME-SHAPED DOPING IN SILICON CRYSTAL DISCS BY NEUTRONIC RADIATION, AND USE OF THIS METHOD FOR PRODUCING PERFORMANCE TYRISTORS|
    EP1540048B1|2002-09-19|2010-05-12|Showa Denko K.K.|Silicon carbide single crystal and method and apparatus for producing the same|
    US7563319B2|2003-02-14|2009-07-21|Sumitomo Mitsubishi Silicon Corporation|Manufacturing method of silicon wafer|
    US10468148B2|2017-04-24|2019-11-05|Infineon Technologies Ag|Apparatus and method for neutron transmutation doping of semiconductor wafers|
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    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    DE2552621A|DE2552621C3|1975-11-24|1975-11-24|Process for the production of n-doped silicon single crystals with a plate-shaped profile of the specific resistance in the radial direction|
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