Patent Application
20080050892
Example embodiments will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings.
Example embodiments will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments are shown. Example embodiments may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of example embodiments to those skilled in the art. For clarification, the thickness of layers and regions illustrated in the drawings are overstated.
Spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. The example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90° or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises”, “comprising,”, “includes” and/or “including”, when used herein, specify the presence of stated features, integers, steps, operations, elements and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and/or groups thereof.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which example embodiments belong. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
The seed layer 6 may be formed to a thickness in a range of about 1 nm-about 10 nm and may be formed by MOCVD (Metal Organic Chemical Vapor Deposition). The seed layer 6 may be formed at a pressure range of about 0.001 Torr-about 10 Torr and a temperature range of about 250° C.-about 500° C. Under these process conditions, the surface property of the seed layer 6 formed on the amorphous material layer 4 may be improved and may affect the film quality of the thin film 8 deposited on the seed layer 6. The amorphous material layer 4 may include one selected from the group consisting of SiO2, SiON and/or Si3N4, which may be used as a material for forming an interlayer insulating film in the manufacture of semiconductor devices.
The seed layer 6 may only provide a nucleation site and thus may not need to be as thick as about 10 nm or greater. Rather, the seed layer 6 may be formed relatively thin. When the seed layer 6 is formed of Sb-doped Ge, the doping concentration of Sb with respect to Ge may be in the range of about 1% to about 30%. In an experiment, when the seed layer 6 was formed with a doping concentration in the above range, the surface property of the seed layer 6 may be improved, and the film quality of the thin film 8 formed on the seed layer 6 may be improved.
In the MOCVD process, a Group VI-precursor, a Group IV-precursor, and a Group V-precursor may each be supplied at a flow rate in the range of about 10 sccm to about 400 sccm. The Group IV-precursor may include at least one selected from the group consisting of (CH3)4Ge, (C2H5)4Ge, (n-C4H9)4Ge, (i-C4H9)4Ge, (C6H5)4Ge, (CH2═CH)4Ge, (CH2CH═CH2)4Ge, (CF2═CF)4Ge, (C6H5CH2CH2CH2)4Ge, (CH3)3(C6H5)Ge, (CH3)3(C6H5CH2)Ge, (CH3)2(C2H5)2Ge, (CH3)2(C6H5)2Ge, CH3(C2H5)3Ge, (CH3)3(CH═CH2)Ge, (CH3)3(CH2CH═CH2)Ge, (C2H5)3(CH2CH═CH2)Ge, (C2H5)3(C5H5)Ge, (CH3)3GeH, (C2H5)3GeH, (C3H7)3GeH, Ge(N(CH3)2)4, Ge(N(CH3)(C2H5))4, Ge(N(C2H5)2)4, Ge(N(i-C3H7)2)4 and/or Ge[N(Si(CH3)3)2]4. The Group V-precursor may include at least one selected from the group consisting of Sb(CH3)3, Sb(C2H5)3, Sb(i-C3H7)3, Sb(n-C3H7)3, Sb(i-C4H9)3, Sb(t-C4H9)3, Sb(N(CH3)2)3, Sb(N(CH3)(C2H5))3, Sb(N(C2H5)2)3, Sb(N(i-C3H7)2)3 and/or Sb[N(Si(CH3)3)2]3. The Group VI-precursor may include at least one selected from the group consisting of Te(CH3)2, Te(C2H5)2, Te(n-C3H7)2, Te(i-C3H7)2, Te(t-C4H9)2, Te(i-C4H9)2, Te(CH2═CH)2, Te(CH2CH═CH2)2 and/or Te[N(Si(CH3)3)2]2.
The thin film 8 may be formed by MOCVD, the same as the seed layer 6. The process conditions for forming the thin film 8 may be similar to the process conditions for forming the seed layer 6. The thin film 8 may be formed at a pressure in the range of about 0.001 Torr-about 10 Torr and a temperature in the range of about 250° C. to about 500° C.
The thin film 8 may be formed of a GeSbTe-based chalcogenide material. For example, the thin film 8 may include a chalcogenide alloy, (e.g., germanium-antimony-tellurium (Ge—Sb—Te), nitrogen-germanium-antimony-tellurium (N—Ge—Sb—Te), arsenic-antimony-tellurium (As—Sb—Te), indium-antimony-tellurium (In—Sb—Te), germanium-bismuth-tellurium (Ge—Bi—Te), tin-antimony-tellurium (Sn—Sb—Te), silver-indium-antimony-tellurium (Ag—In—Sb—Te), gold-indium-antimony-tellurium (Au—In—Sb—Te), germanium-indium-antimony-tellurium (Ge—In—Sb—Te), selenium-antimony-tellurium (Se—Sb—Te), tin-indium-antimony-tellurium (Sn—In—Sb—Te) and/or arsenic-germanium-antimony-tellurium (As—Ge—Sb—Te)). Alternatively, the thin film 8 may include a Group VA element-antimony-tellurium (e.g., tantalum-antimony-tellurium (Ta—Sb—Te), niobium-antimony-tellurium (Nb—Sb—Te) and/or vanadium-antimony-tellurium (V—Sb—Te)) and/or Group VA element-antimony-selenium (e.g., tantalum-antimony-selenium (Ta—Sb—Se), niobium-antimony-selenium (Nb—Sb—Se) and/or vanadium-antimony-selenium (V—Sb—Se)). Alternatively, the thin film 8 may include a Group VIA element-antimony-tellurium (e.g., tungsten-antimony-tellurium (W—Sb—Te), molybdenum-antimony-tellurium (Mo—Sb—Te) and/or chromium-antimony-tellurium (Cr—Sb—Te)) and/or a Group VIA element-antimony-selenium (e.g., tungsten-antimony-selenium (W—Sb—Se), molybdenum-antimony-selenium (Mo—Sb—Se) and/or chromium-antimony-selenium (Cr—Sb—Se)).
Although it is described above that the thin film 8 may be formed of ternary phase-change chalcogenide alloys, the thin film 8 may be formed of binary phase-change chalcogenide alloys and/or quaternary phase-change chalcogenide alloys. The binary phase-change chalcogenide alloy may include one or more materials of Ga—Sb, Ge—Sb, In—Sb, In—Se, Sb2—Te3 and/or Ge—Te alloy. The ternary phase-change chalcogenide alloy may include one or more materials of Ag—In—Sb—Te, (Ge—Sn)—Sb—Te, Ge—Sb—(Se—Te) and/or Te81—Ge15—Sb2—S2 alloy.
It may be relatively difficult to form the thin film 8 on the SiO2 material layer 4 using a conventional MOCVD process. When the seed layer 6 is formed before forming the thin film 8, the thin film 8 of improved quality may be able to be formed on the SiO2 material layer 4 even though the plasma process may not be used. The thin film 8, having improved crystallinity and improved surface morphology, may be more easily formed on the amorphous material layer 4 (e.g., a SiO2 layer, a Si3N4 layer and/or a SiON layer) by simple MOCVD. The seed layer 6 may be formed of a material of the same type as that of the material forming the thin film 8 using an in-situ process, so that the formation method of the thin film 8 may be simpler.
The switching transistor 20 may include a source region 12 doped with n-type impurities, a drain region 14 doped with n-type impurities, a channel region 16 between the source and drain regions 12 and 14 and a gate stack formed on the channel region 16. The gate stack may include a gate insulating film 18 and a gate electrode 19 that are sequentially stacked. A first insulating film 22 may be stacked on the switching transistor 20, and a first contact hole h1 through which the drain region 14 is exposed may be formed in the first insulating film 22. A conductive plug 24 may be formed in the first contact hole h1 and may connect the drain region 14 to the storage node S1. The first insulating film 22 may be formed of a dielectric material (e.g., SiO2, Si3N4 and/or SiON).
The storage node S1 may include a bottom electrode (BE) 30, a bottom electrode contact (BEC) 30a, a seed layer 36, a thin film 38 and a top electrode (TE) 40 which are sequentially stacked. A second insulating layer 32 may be formed of a dielectric material (e.g., SiO2, Si3N4 and/or SiON) on the BE 30. A second contact hole h2 exposing a predetermined or given area of the BE 30 may be formed in the second insulating layer 32. The BEC 30a may be formed in the second contact hole h2 to serve as a resistive heater. The seed layer 36 may be formed on the second insulating layer 32 and may cover the upper surface of the BEC 30a. The thin film 38 may be formed on the seed layer 36. The TE 40 may be formed on the thin film 38. The BEC 30a may serve as a resistive heater and thus may heat the thin film 38 according to a set or reset pulse which is applied to the BEC 30a. The BEC 30a may be formed of TiAlN and/or TiN. The BEC 30a may contact the thin film 38 in a relatively small area because it may have a smaller width than the upper surface of the BE 30. The heating efficiency of the thin film 38 may be improved.
The seed layer 36 may have improved adhesion to the BEC 30a formed of TiAlN and/or TiN and the second insulating layer 32 formed of SiO2, SiON and/or Si3N4 and may provide a nucleation site for the formation of the thin film 38. The surface morphology and the crystallinity of the thin film 38 formed on the seed layer 36 may be enhanced to thereby manufacture the improved-quality thin film 38. Because the seed layer 6 is formed of a material of the same type as the material used to form the thin film 38, the seed layer 6 may also have improved adhesion to the thin film 38. The seed layer 36 may be formed of Ge, Sb, Te, Sb2Te3 and/or Sb-doped Ge and may be formed by MOCVD. The seed layer 36 may be formed to a thickness of about 1 nm to about 10 nm. The thin film 38 may be formed of a GeSbTe-based chalcogenide material.
Referring to
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The seed layer 36 may provide a nucleation site for the formation of the thin film 38, and thus the surface morphology and the crystallinity of the thin film 38 may be improved, resulting in an improved-quality thin film 38. The seed layer 36 may be formed of a material of the same type as that of a material used to form the thin film 38, and thus may have improved adhesion to the thin film 38. In addition, deposition processes for forming the seed layer 36 and the thin film 38 may be consecutively performed while maintaining the vacuum state of a deposition chamber by an in-situ process.
When the seed layer 36 is formed of Sb-doped Ge, the doping concentration of Sb with respect to Ge may be about 1% to about 30%. In an experiment, when the seed layer 36 was formed at the doping concentration range, the surface property of the seed layer 36 may be improved and the film quality of the thin film 38 formed on the seed layer 36 may be improved.
In the above MOCVD, each of the Group IV-precursor, the Group V-precursor and the Group VI-precursor may be supplied at a flowrate of about 10 sccm to about 400 sccm. The Group IV-precursor may include at least one selected from the group consisting of (CH3)4Ge, (C2H5)4Ge, (n-C4H9)4Ge, (i-C4H9)4Ge, (C6H5)4Ge, (CH2═CH)4Ge, (CH2CH═CH2)4Ge, (CF2═CF)4Ge, (C6H5CH2CH2CH2)4Ge, (CH3)3(C6H5)Ge, (CH3)3(C6H5CH2)Ge, (CH3)2(C2H5)2Ge, (CH3)2(C6H5)2Ge, CH3(C2H5)3Ge, (CH3)3(CH═CH2)Ge, (CH3)3(CH2CH═CH2)Ge, (C2H5)3(CH2CH═CH2)Ge, (C2H5)3(C5H5)Ge, (CH3)3GeH, (C2H5)3GeH, (C3H7)3GeH, Ge(N(CH3)2)4, Ge(N(CH3)(C2H5))4, Ge(N(C2H5)2)4, Ge(N(i-C3H7)2)4 and/or Ge[N(Si(CH3)3)2]4. The Group V-precursor may include at least one selected from the group consisting of Sb(CH3)3, Sb(C2H5)3, Sb(i-C3H7)3, Sb(n-C3H7)3, Sb(i-C4H9)3, Sb(t-C4H9)3, Sb(N(CH3)2)3, Sb(N(CH3)(C2H5))3, Sb(N(C2H5)2)3, Sb(N(i-C3H7)2)3 and/or Sb[N(Si(CH3)3)2]3. The Group VI-precursor may include at least one selected from the group consisting of Te(CH3)2, Te(C2H5)2, Te(n-C3H7)2, Te(i-C3H7)2, Te(t-C4H9)2, Te(i-C4H9)2, Te(CH2═CH)2, Te(CH2CH═CH2)2 and/or Te[N(Si(CH3)3)2]2. The thin film 38 may be formed by MOCVD like the seed layer 36. The process conditions for the thin film 38 may be similar to those for the seed layer 36. The thin film 38 may be formed at a temperature of about 250° C. to about 500° C. and a pressure of about 0.001 Torr to about 10 Torr.
The thin film 38 may be formed of a GeSbTe-based chalcogenide material. For example, the thin film 38 may include chalcogenide alloys, (e.g., germanium-antimony-tellurium (Ge—Sb—Te), nitrogen-germanium-antimony-tellurium (N—Ge—Sb—Te), arsenic-antimony-tellurium (As—Sb—Te), indium-antimony-tellurium (In—Sb—Te), germanium-bismuth-tellurium (Ge—Bi—Te), tin-antimony-tellurium (Sn—Sb—Te), silver-indium-antimony-tellurium (Ag—In—Sb—Te), gold-indium-antimony-tellurium (Au—In—Sb—Te), germanium-indium-antimony-tellurium (Ge—In—Sb—Te), selenium-antimony-tellurium (Se—Sb—Te), tin-indium-antimony-tellurium (Sn—In—Sb—Te) and/or arsenic-germanium-antimony-tellurium (As—Ge—Sb—Te)). Alternatively, the thin film 8 may include a Group VA element-antimony-tellurium (e.g., tantalum-antimony-tellurium (Ta—Sb—Te), niobium-antimony-tellurium (Nb—Sb—Te) and/or vanadium-antimony-tellurium (V—Sb—Te)) and/or a Group VA element-antimony-selenium (e.g., tantalum-antimony-selenium (Ta—Sb—Se), niobium-antimony-selenium (Nb—Sb—Se) and/or vanadium-antimony-selenium (V—Sb—Se)). Alternatively, the thin film 8 may include a Group VIA element-antimony-tellurium (e.g., tungsten-antimony-tellurium (W—Sb—Te), molybdenum-antimony-tellurium (Mo—Sb—Te) and/or chromium-antimony-tellurium (Cr—Sb—Te)) and/or a Group VIA element-antimony-selenium (e.g., tungsten-antimony-selenium (W—Sb—Se), molybdenum-antimony-selenium (Mo—Sb—Se) and/or chromium-antimony-selenium (Cr—Sb—Se)).
Although it is described above that the thin film 8 may be formed of ternary phase-change chalcogenide alloys, the thin film 8 may be formed of binary phase-change chalcogenide alloys and/or quaternary phase-change chalcogenide alloys. The binary phase-change chalcogenide alloy may include one or more materials of a Ga—Sb, Ge—Sb, In—Sb, In—Se, Sb2—Te3 and/or Ge—Te alloy. The ternary phase-change chalcogenide alloy may include one or more materials of an Ag—In—Sb—Te, (Ge—Sn)—Sb—Te, Ge—Sb—(Se—Te) and/or Te81—Ge15—Sb2—S2 alloy. The TE 40 may be formed on the thin film 38. The material used to form the TE 40 and the formation method thereof may be known in the field of PRAM device manufacturing processes, so detailed descriptions thereof will be omitted.
Referring to the storage node S3 of
It may be relatively difficult to form a thin film on a SiO2 substrate using a conventional MOCVD process. When a seed layer is formed prior to forming the thin film, an improved-quality thin film may be formed on the SiO2 substrate even when a plasma process is not used. A thin film with an improved surface morphology and improved crystallinity may be more easily formed on an amorphous material layer (e.g., a SiO2 layer, a Si3N4 layer and/or an SiON layer) using a MOCVD process. The seed layer may be formed of a material of the same type as the material used to form the thin film and thus may be formed by an in-situ process. The formation of the thin film according to example embodiments may be relatively simple. When a PRAM device including a thin film is manufactured using the same method as the thin film forming method according to example embodiments, it may be possible to form a improved-quality thin film on two different types of surfaces, for example, an insulating film formed of SiON and/or SiO2 and a BEC formed of TiAlN and/or TiN, to a relatively uniform thickness at the same time. Thus, the reliability and the reproducibility of the PRAM device may be improved.
While example embodiments have been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2006-0055912 | Jun 2006 | KR | national |
