140 results about "Oxygen precipitates" patented technology

The invention relates to a silicon wafer and an epitaxial silicon wafer, which are doped with arsenic (As) as an n-type dopant and are excellent in gettering characteristics. A first silicon wafer has a resistivity of 10 OMEGAcm to 0.001 OMEGAcm as a result of addition of arsenic and has a nitrogen concentration of 1x1013 to 1x1015 atoms/cm3. A second silicon wafer has a resistivity of 0.1 OMEGAcm to 0.005 OMEGAcm and a nitrogen concentration of 1x1014 to 1x1015 atoms/cm3. A third silicon wafer has a resistivity of 0.005 OMEGAcm to 0.001 OMEGAcm and a nitrogen concentration of 1x1013 to 3x1014 atoms/cm3. An epitaxial silicon wafer derived from any of the first to third silicon wafers by forming an epitaxial layer in the surface layer portion is provided. In producing this epitaxial silicon wafer, epitaxial layer formation is desirably carried out after subjecting the silicon wafer to heat treatment for forming oxygen precipitates under conditions of a temperature not lower than 700° C. but lower than 900° C. and a period of 30 minutes to 4 hours. By these, an oxygen precipitate density can be secured and a sufficient gettering effect can be produced in the device producing process in spite of their being n-type silicon wafers doped with a high concentration of arsenic.

By using a two-step RTP (rapid thermal processing) process, the wafer is provided which has an ideal semiconductor device region secured by controlling fine oxygen precipitates and OiSFs (Oxidation Induced Stacking Fault) located on the surface region of the wafer. By performing the disclosed two-step rapid thermal process, the distribution of defects can be accurately controlled and an ideal device active zone can be formed up to a certain distance from the surfaces of the wafer. In addition, it is possible to maximize the internal gettering (IG) efficiency by enabling the oxygen precipitates and the bulk stacking faults to have constant densities in the depth direction in an internal region of the wafer, that is, the bulk region. In order to obtain the constant concentration profile of the oxygen precipitates and the bulk stacking faults in the bulk region, the wafer is subjected to the aforementioned two-step rapid thermal process in a predetermined mixed gas atmosphere.

The present invention is directed to a single crystal Czochralski-type silicon wafer, and a process for the preparation thereof, which has at least a surface layer of high resistivity, the layer having an interstitial oxygen content which renders it incapable of forming thermal donors in an amount sufficient to affect resistivity upon being subjected to a conventional semiconductor device manufacturing process. The present invention further directed to a silicon on insulator structure derived from such a wafer.

A high-resistance silicon wafer is manufactured in which a gettering ability, mechanical strength, and economical efficiency are excellent and an oxygen thermal donor is effectively prevented from being generated in a heat treatment for forming a circuit, which is implemented on the side of a device maker. A heat treatment for forming an oxygen precipitate nucleus is performed at 500 to 900° C. for 5 hours or more in a non-oxidizing atmosphere and a heat treatment for growing an oxygen precipitate is performed at 950 to 1050° C. for 10 hours or more on a high-oxygen and carbon-doped high-resistance silicon wafer in which resistivity is 100 Ωcm or more, an oxygen concentration is 14×10¹⁷ atoms/cm³ (ASTM F-121, 1979) or more and a carbon concentration is 0.5×10¹⁶ atoms/cm³ or more. By these heat treatments, a remaining oxygen concentration in the wafer is controlled to be 12×10¹⁷ atoms/cm³ (ASTM F-121, 1979) or less. Thus, there is provided a high-resistance, low-oxygen and high-strength silicon wafer in which resistivity is 100 Ωcm or more and an oxygen precipitate (BMD) having a size of 0.2 μm is formed so as to have high density of 1×10⁴/cm² or more.

It is possible to provide a silicon wafer that as well as being free of COPs and dislocation clusters, has defects (grown-in defects including silicon oxides), which are not overt in an as-grown state, such as OSF nuclei and oxygen precipitate nuclei existing in the PV region, to be vanished or reduced, by adopting a method for producing a silicon wafer, the method comprising the steps of: growing a single crystal silicon ingot by the Czochralski method; cutting a silicon wafer out of the ingot; subjecting the wafer to an RTP at 1,250° C. or more for 10 seconds or more in an oxidizing atmosphere; and removing a grown-in defect region including silicon oxides in the vicinity of wafer surface layer after the RTP.

A method of manufacturing an SOI wafer includes a bonding step, a thinning and a bonding annealing step. Assuming refractive index n1 of SiO₂ as 1.5, refractive index n2 of Si as 3.5, and optical thickness t_OP of the silicon oxide film 2 and the SOI layer 15 in the infrared wavelength region as t_OP=n1×t1+n2×t2, the thickness t1 of the silicon oxide film 2 and thickness t2 of the SOI layer so as to satisfy a relation of 0.1λ<t_OP<2λ, and so as to make (t1×n1)/(t2×n2) fall within 0.2 to 3. By nuclei killer annealing carried out before the bonding annealing, density of formation of oxygen precipitate in the base wafer after the bonding annealing is adjusted to less than 1×10⁹/cm³. This configuration successfully provides a method of manufacturing the SOI wafer having the thin silicon oxide film and the SOI layer, and being less likely to cause warping.

An epitaxial wafer and a high-temperature heat treatment wafer having an excellent gettering capability are obtained by performing epitaxial growth or a high-temperature heat treatment. A relational equation relating the density to the radius of an oxygen precipitate introduced in a silicon crystal doped with nitrogen at the time of crystal growth can be derived from the nitrogen concentration and the cooling rate around 1100° C. during crystal growth, and the oxygen precipitate density to be obtained after a heat treatment can be predicted from the derived relational equation relating the oxygen precipitate density to the radius, the oxygen concentration, and the wafer heat treatment process. Also, an epitaxially grown wafer and a high-temperature annealed wafer whose oxygen precipitate density has been controlled to an appropriate density are obtained, using conditions predicted by the method.

A process for imparting controlled oxygen precipitation behavior to a single crystal silicon wafer. Specifically, prior to formation of the oxygen precipitates, the wafer bulk comprises dopant stabilized oxygen precipitate nucleation centers. The dopant is selected from a group consisting of nitrogen and carbon, and the concentration of the dopant is sufficient to allow the oxygen precipitate nucleation centers to withstand thermal processing, such as an epitaxial deposition process, while maintaining the ability to dissolve any grown-in nucleation centers.

A process for the preparation of low resistivity arsensic or phosphorous doped (N+/N++) silicon wafers which, during the heat treatment cycles of essentially any arbitrary electronic device manufacturing process, reliably form oxygen precipitates.

It is possible to efficiently capture heavy metal contamination due to ion implantation or high-temperature heat treatment in a bulk layer.

It is characterized that the present method comprises: a step of implanting oxygen ions into a wafer 11; a step of applying first heat treatment to a wafer under a predetermined gas atmosphere at 1,300 to 1,390° C. and forming a buried oxide layer 12 and an SOI layer 13 by applying first heat treatment to a wafer at 1,300 to 1390° C.; a second heat treatment step in which a wafer before oxygen ions are implanted has an oxygen concentration of 9×10¹⁷ to 1.8×10¹⁸ atoms/cm³ (old ASTM) and a buried oxide layer is formed entirely or locally in the wafer to form oxygen precipitate nuclei 14b formed in the wafer before the oxygen ion implantation step or between the oxygen ion implantation step and the first heat treatment step; and a third heat treatment step of growing oxygen precipitate nuclei 14b formed in the wafer so as to be oxygen precipitates 14c.

A silicon epitaxial wafer 100 formed by growing a silicon epitaxial layer 2 on a silicon single crystal substrate 1, produced by a CZ method, and doped with boron so that a resistivity thereof is in the range of 0.009 Ω·cm or higher and 0.012 Ω·cm or lower. The silicon single crystal substrate 1 has a density of the oxygen precipitation nuclei of 1×10¹⁰ cm⁻³ or higher. A width of a no-oxygen-precipitation-nucleus-forming-region 15, formed between the silicon epitaxial layer 2 and the silicon single substrate 1, is in the range of more than 0 μm and less than 10 μm. Thereby, provided is a silicon epitaxial wafer using a boron doped p⁺ CZ substrate, wherein a formed width of no-oxygen-precipitation-nucleus-forming-region is reduced sufficiently, and oxygen precipitates can be formed having a density sufficient enough to exert an IG effect.

An object of the present invention is to provide an epitaxial wafer on which dislocation is preventable even when a LSA treatment is performed in device processes. An epitaxial wafer according to the present invention includes a wafer 11 whose nitrogen concentration is 1×10¹² atoms/cm³ or more or whose specific resistance is 20 mΩ·cm or less by boron doping, and an epitaxial layer 12 provided on the wafer 11. On the wafer 11, if a thermal treatment is performed at 750° C. for 4 hours and then at 1,000° C. for 4 hours, polyhedron oxygen precipitates grow predominantly over plate-like oxygen precipitates. Therefore, in the device processes, plate-like oxygen precipitates cannot be easily formed. As a result, even when the LSA treatment is performed after various thermal histories in the device processes, it is possible to prevent the dislocation, which is triggered by oxygen precipitates, from generating.

The present invention relates to a single crystal silicon ingot or wafer wherein the lateral incorporation effect of intrinsic point defects has been manipulated such that the formation of agglomerated intrinsic point defects and/or oxygen precipitate clusters in a ring extending radially inward from about the lateral surface of the ingot segment is limited.

The invention relates to a method for producing electrodeposited cobalt, which belongs to the technical field of production methods of the electrodeposited cobalt. The method for producing the electrodeposited cobalt by a non-hydrochloric acid electrolyte is characterized in that the method comprises the steps of: the preparation of a CoCl2 solution, extraction and transformation, dechlorination, the removal of an organic substance by a physical method, the preparation of a cobalt electrolyte, and the production of the electrodeposited cobalt. The method adds an acid fog inhibitor into the electrolyte to ensure that the expansive force on the surface of the electrolyte is reduced and oxygen precipitated by an anode smoothly passes through the liquid level so as to prevent acid from being brought into production field. The method effectively improves work environment and prevent the pollution to the ambient environment. The method for producing the electrodeposited cobalt by the non-hydrochloric acid electrolyte, due to adopting solution transformation and chlorine washing processes, ensures that Cl<-> in the electrolyte is lower than 0.1g.l<-1>, and basically meets the requirement of no precipitation of chlorine gas during the electrodeposition.

The present invention is directed to a single crystal Czochralski-type silicon wafer, and a process for the preparation thereof, which has a non-uniform distribution of stabilized oxygen precipitate nucleation centers therein. Specifically, the peak concentration is located in the wafer bulk and a precipitate-free zone extends inward from a surface.

This invention generally relates to a process for suppressing oxygen precipitation in epitaxial silicon wafers having a heavily doped silicon substrate and a lightly N-doped silicon epitaxial layer by dissolving existing oxygen clusters and precipitates within the substrate. Furthermore, the formation of oxygen precipitates is prevented upon subsequent oxygen precipitation heat treatment.

There is obtained a silicon wafer which has a large diameter, where no slip generated therein in a wide range of a density of oxygen precipitates even though a heat treatment such as SLA or FLA is applied thereto, and which has high strength.

First, by inputting as input parameters combinations of a plurality of types of oxygen concentrations and thermal histories set for manufacture of a silicon wafer a Fokker-Planck equation is solved to calculate each of a diagonal length L and a density D of oxygen precipitates in the wafer after a heat treatment step to form the oxygen precipitates (11) and immediately before a heat treatment step of a device manufacturing process is calculated. Then, a maximum heat stress S acting in a tangent line direction of an outer peripheral portion of the wafer in the heat treatment step of the device manufacturing process is calculated based on a heat treatment furnace structure and a heat treatment temperature used in the heat treatment step of the device manufacturing process, and then an oxygen concentration or the like satisfying the following Expression (1) is determined:

12000×D^−0.26≦L≦51000×S^−1.55  (1)

[Problem] An object of the present invention is to provide an epitaxial substrate and a method for producing the same capable of suppressing metal contamination and thereby reducing occurrence of white defects of a solid state imaging sensor by maintaining sufficient gettering capability during a device manufacturing process.

[Solving Means] The present invention is a method of producing an epitaxial substrate, comprising a step of growing an epitaxial layer on a silicon substrate containing carbon as a dopant to form an epitaxial substrate; and, after the formation of the epitaxial substrate, a step of applying a first thermal treatment and a second thermal treatment to the epitaxial substrate such that a density of oxygen precipitates in a surface layer of the silicon substrate constituting the epitaxial substrate is larger than a density of oxygen precipitates at a center of the silicon substrate in a thickness direction.

This disclosure is aimed at providing a method for producing an epitaxial wafer allowing uniform occurrence of oxygen precipitate in a substrate plane in the radial direction in a base plate and excelling in the crystal quality of an epi-layer.

A method for the production of an epitaxial wafer, characterized by using as a substrate a base plate of nitrogen- and carbon-added silicon single crystal having a nitrogen concentration of 5×10¹⁴ to 5×10¹⁵ atoms/cm³ and a carbon concentration of 1×10¹⁶ to 1×10¹⁸ atoms/cm³, having a crystal growth condition during the production of silicon single crystal in a range in which the whole surface of substrate becomes an OSF region, and being pulled at a cooling speed of not less than 4° C./minute between 1100 and 1000° C. during the growth of crystal, and depositing the silicon single crystal layer on the surface of the substrate by the epitaxial method.

By specifying an initial oxygen concentration in a silicon single crystal and a concentration of thermal donors produced according to a thermal history from 400° C. to 550° C. that the silicon single crystal undergoes during crystal growth, a nucleation rate of oxygen precipitates produced in the silicon single crystal while the silicon single crystal is subjected to a heat treatment is determined. Further, by specifying the heat treatment condition of the silicon single crystal, an oxygen precipitate density and an amount of precipitated oxygen under a given heat treatment condition are predicted by calculation.

The present invention is directed to a single crystal Czochralski silicon wafer having a non-uniform distribution of lattice vacancies with peak concentration at a hypothetical In the bulk of the wafer between the central plane and a surface, such that after a heat treatment cycle in essentially any electronic device manufacturing process, the wafer forms oxygen precipitates in the bulk and a thin or shallow no-sedimentation zone.