Classifications

• • 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
  • C30B15/00—Single-crystal growth by pulling from a melt, e.g. Czochralski method
  • C30B15/20—Controlling or regulating
• • 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
  • C30B15/00—Single-crystal growth by pulling from a melt, e.g. Czochralski method
  • C30B15/02—Single-crystal growth by pulling from a melt, e.g. Czochralski method adding crystallising materials or reactants forming it in situ to the melt
  • C30B15/04—Single-crystal growth by pulling from a melt, e.g. Czochralski method adding crystallising materials or reactants forming it in situ to the melt adding doping materials, e.g. for n-p-junction
• • 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
  • C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
  • C30B29/02—Elements
  • C30B29/06—Silicon

Definitions

• different impurities in the melt may segregate at different rates which causes their ratio to vary over its length which may cause a type change in the ingot. This causes a portion of the ingot to fall outside of product specifications which increases the "non-prime" portion of the ingot .
• Figure 2 is a binary phase diagram for silicon containing impurity "A" that has a segregation coefficient less than 1;
• concentration of impurity A in the solid can be represented as a function of the fraction solidified using the following:
• the resistivity is related to the concentration of the dopant element by
• Phosphorous has a segregation coefficient (0.35) that is less than boron (0.80) which causes phosphorous to
• a dopant such as gallium or indium which has a smaller segregation
• the first dopant that is added to the crucible is gallium.
• a relatively small amount of gallium is added to the
• indium may be used as the first dopant.
• concentration of indium in the melt after indium is added to the crucible may be less than about 0.5 ppma (as measured after addition of indium and before pulling of the sample ingot) or even less than about 0.1 ppma, less than 0.01 ppma or less than about 0.001 ppma indium.
• concentration of indium in the melt after indium addition is from about 0.00001 ppma to about 0.5 ppma or from about 0.0001 ppma to about 0.1 ppma.
• the amount of alloy that is added to the crucible may depend on the size of the charge and the amount of gallium incorporated therein. In some embodiments, about 0.5 grams to about 50 grams or about 1 gram to about 15 grams of gallium or indium alloy is added to the crucible.
• the first dopant i.e., gallium and/or indium
• the polysilicon material is melted down.
• the amount of second dopant used may be determined based on Equations 2-5 provided above .
• the melting temperature of the material is raised (e.g., from the 29.7°C melting temperature of pure gallium when gallium is used) which eases transfer into the crucible.
• the solid-phase alloy also stays as a solid until it is melted in the polysilicon charge, allowing for ease of handling without the need to keep the material (e.g., pure gallium) refrigerated or cooled to below its melting temperature.
• phosphorous impurity accumulation was modeled and is shown in Figure 5. As shown in Figure 5, type-change from P-type to N-type occurred at about 17% solidified fraction due to the accumulation of phosphorous relative to boron.
• phosphorous and with and without 3xl0 14 atoms/cm 3 gallium are shown in Figure 7. As shown in Figure 7, when gallium was not used the type change to N-type occurred at about 10% of the solidified fraction. Use of gallium allowed the ingot to remain P-type throughout the length of the body.
• a master gallium- silicon alloy was produced.
• the alloy had a gallium concentration in the range of 0.1 to 0.3 wt%. Amounts of silicon and gallium were weighed. The materials were melted and frozen in a quartz container in low gradient furnace. The alloy material was separated from the container and acid washed in HF. The alloy was then dried, crushed, sized and cleaned to less than 3 mm. The

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• Crystallography & Structural Chemistry (AREA)
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• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Crystals, And After-Treatments Of Crystals (AREA)

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• 2017
  • 2017-12-27 US US15/855,466 patent/US10920337B2/en active Active
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