Classifications

• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10B—ELECTRONIC MEMORY DEVICES
  • H10B12/00—Dynamic random access memory [DRAM] devices
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L28/00—Passive two-terminal components without a potential-jump or surface barrier for integrated circuits; Details thereof; Multistep manufacturing processes therefor
  • H01L28/40—Capacitors
  • H01L28/60—Electrodes
  • H01L28/75—Electrodes comprising two or more layers, e.g. comprising a barrier layer and a metal layer
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L28/00—Passive two-terminal components without a potential-jump or surface barrier for integrated circuits; Details thereof; Multistep manufacturing processes therefor
  • H01L28/40—Capacitors
  • H01L28/60—Electrodes
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L28/00—Passive two-terminal components without a potential-jump or surface barrier for integrated circuits; Details thereof; Multistep manufacturing processes therefor
  • H01L28/40—Capacitors
  • H01L28/55—Capacitors with a dielectric comprising a perovskite structure material

Definitions

• the invention is in the field of semiconductor technology and relates to a microelectronic structure which comprises at least one substrate and a first conductive layer. Such microelectronic structures are used in particular in semiconductor memories.
• materials with a high dielectric constant (epsilon> 20) or with ferroelectric properties are increasingly being used.
• the main materials currently of interest are metal oxide dielectrics, which are deposited at relatively high temperatures in the presence of oxygen.
• Prominent representatives are, for example, barium strontium titanate ((Ba, Sr) Ti0 3 , BST), lead zirconate titanate (PbZrTi0 3 , PZT), strontium bismuth tantalate (SrBi 2 Ta 2 0 9 , SBT) and descendants aforementioned materials.
• the barrier layer consists of titanium or titanium-titanium nitride. Unfortunately, titanium is oxidized relatively quickly at the relatively high deposition temperatures (above 500 ° C.) and thereby prevents a conductive connection between the electrode and the silicon. A number of measures have therefore been proposed to protect the barrier layer from oxidation during the deposition of the metal oxides.
• the first conductive layer consists of at least one basic material al with at least one oxygen-binding additive, which contains at least one element from subgroup 4 or from
• the basic idea of the invention is to provide a conductive layer with suitable oxygen-binding additives. These are intended to prevent diffusion of oxygen or of diffusion-friendly oxides and thus protect the structures located under the conductive layer from oxidation.
• the first conductive layer consists of at least one base material which is on the one hand electrically conductive and on the other hand largely resistant to oxygen, and in which the oxygen-binding additive is distributed as evenly as possible. It is important that the oxygen-binding additive is already present in the base material prior to the action of oxygen on the structures to be protected and thereby prevents oxygen diffusion through the first conductive layer.
• the at least one oxygen-binding additive with the base material which can consist of one or more components, usually forms an alloy or a mixed layer, the oxygen-binding additive in the base material also being able to be present, at least in part, as a finely divided precipitate.
• Advantages of a uniform distribution of the oxygen-binding additive are, in particular, the uniform oxygen absorption capacity of the first conductive layer, the adaptation of the absorption capacity by varying the layer thickness of the first conductive layer and a uniform and largely stress-free volume increase due to the oxygen binding.
• Elements from the fourth subgroup and from the lanthanum group have proven to be advantageous oxygen-binding additives, zirconium, hafnium, Cerium or a combination of these elements is preferred.
• the oxygen-binding additive to the base material in a weight proportion between 0.5% and 20%, preferably between 1% and 10%.
• Suitable base materials for the first conductive layer are noble metals, in particular platinum, palladium, rhodium, iridium, ruthenium, osmium, rhenium, conductive oxides of the aforementioned metals or a mixture of the aforementioned compounds and elements.
• the microelectronic structure has a metal oxide dielectric that at least partially covers the first conductive layer.
• the metal oxide dielectric serves, in particular in the case of semiconductor memories, as a capacitor dielectric, the first conductive layer being at least part of an electrode of the storage capacitor. Since the metal oxide dielectric is usually applied directly to the first conductive layer, when it is deposited in an oxygen-containing atmosphere, a barrier layer, which is preferably located under the first conductive layer, must be protected against the attack of oxygen. This is achieved by the oxygen-binding additive, preferably hafnium, in the first conductive layer.
• the metal oxide dielectric preferably consists of a compound of the general type ABO, where 0 stands for oxygen, A and B each for at least one element from the group barium, strontium, tantalum, titanium, lead, zirconium, niobium, lanthanum, calcium and potassium.
• the general compound ABO often has a perovskite-like crystal structure, which is crucial for the desired dielectric (high dielectric constant) or for the ferroelectric properties.
• An example of such a connection is SrBi 2 Ta 2 0 9 .
• a second conductive layer which preferably consists of a noble metal, in particular platinum, is preferably arranged between the first conductive layer and the metal oxide dielectric.
• This additional conductive layer on the one hand represents an inner and smooth interface for the growth of the metal oxide dielectric and on the other hand supports the crystal growth of the metal oxide dielectric during its deposition or during a subsequent temperature treatment and also represents additional oxidation protection.
• the binding capacity of the first conductive layer with regard to oxygen should be suitably set by choosing the admixture level, so that additional additional layers which prevent oxygen diffusion are not necessary.
• an admixture between 8 and 10% is sufficient to almost completely suppress the oxygen diffusion occurring during the deposition or tempering of the metal oxide dielectrics through the first conductive layer with a thickness of approximately 100 nm.
• the first conductive layer can be made thinner in order to save costs.
• the second part of the object is achieved by a method for producing a microelectronic structure which comprises at least one substrate and a first conductive layer, the first conductive layer consisting of at least one base material with at least one oxygen-binding additive which comprises at least one element the 4th subgroup or from the lanthanum group, with the following steps: - providing the substrate; and - Simultaneous application of the base material and the oxygen-binding additive to the substrate to form the first conductive layer.
• the base material and the oxygen-binding additive are preferably applied simultaneously to the substrate, so that the first conductive layer is formed there as a mixture of the base material and the oxygen-binding additive.
• the deposition temperatures and the amount of admixture of the oxygen-binding additive the latter can be at least partially eliminated from the base material or form a mixed crystal together with the base material.
• the base material and the oxygen-binding additive to the substrate by means of a physical atomization process (sputtering).
• sputtering a physical atomization process
• This is preferably carried out using a common source for the base material and the oxygen-binding additive, this being done in a simple manner by means of a sputtering target consisting of the base material with disks placed thereon, which contain the oxygen-binding additive. It is therefore not necessary to provide a mixed source. Rather, the type of oxygen-binding additive and its admixture level can be varied in a simple manner.
• an iridium layer with an oxygen-binding hafnium additive is preferably produced at a pressure of approximately 0.02 mbar and a substrate temperature of approximately 200 ° C.
• the metal oxide dielectric is applied by means of the MOCVD method or spin-on method.
• the microelectronic structure is preferably used in a memory device, the first conductive layer representing a first electrode which, together with a further electrode and the metal oxide dielectric arranged between these electrodes, form a storage capacitor.
• a plurality of such storage capacitors is preferably arranged on a substrate.
• the microelectronic structure is also generally suitable as an oxygen diffusion barrier in order to protect oxygen-sensitive regions of the microelectronic structure, in particular a semiconductor structure, from an oxygen attack.
• FIG. 1 to 3 different embodiments of storage capacitors using the microelectronic according to the invention
• Structure, and Figure 4 shows a sputter reactor for producing such a microelectronic structure.
• FIG. 1 shows a storage capacitor 5 which is arranged on a substrate 10.
• the storage capacitor 5 comprises a lower electrode 15, which is built up in layers from an iridium oxide layer 20, an iridium layer 25 and a plate layer 30.
• ruthenium oxide and ruthenium instead of iridium oxide and iridium is also possible.
• the iridium oxide layer 20 and the iridium layer 25 constitute the first conductive layer.
• At least one of the iridium oxide 20 and iridium layers 25 contains an oxygen-binding additive, which is preferably by Hafnium is formed. This can depend on his
• Addition levels between 1% and 10% form a mixed crystal with the respective layer or are partially present as a precipitate.
• the platinum layer 30 represents the second conductive layer.
• the layered lower electrode 15 was preferably structured by etching the three layers 20, 25 and 30 together. This is done, for example, by an anisotropic etching process with a high physical component, which is achieved, for example, in an argon sputtering process. To support the argon plasma, chlorine or hydrogen bromide (HBr) can be added.
• HBr hydrogen bromide
• a titanium-containing barrier layer 35 is located below the lower electrode 15. This serves on the one hand to improve the adhesive properties of the lower electrode 15 on the substrate 10 and on the other hand to prevent silicon diffusion. This is particularly necessary because the lower electrode 15 is connected to a selection transistor (not shown here) through a contact hole 40 in the substrate 10 filled with polysilicon.
• the barrier layer 35 consisting of titanium-titanium nitride is preferably structured together with the lower electrode 15. As a result, only a single etching step is necessary for the structure consisting of lower electrode 15 and barrier layer 35.
• the lower electrode 15 is completely covered by an SBT layer 45, the latter representing the metal oxide dielectric.
• the SBT layer 45 thus also has direct contact with the edge regions of the barrier layer 35. This means that these regions are unprotected when the SBT layer 45 is deposited. However, since the depth of penetration of the acid diffusion into the barrier layer 35 is limited, the entire barrier layer 35 is not oxidized but only the areas immediately adjacent to the SBT layer 45.
• the central region of the barrier layer 35 which is located in particular in the region of the contact hole 40, is protected from oxidation by the lower electrode 15 arranged above it and in particular by the hafnium additive located in the iridium oxide layer 20 or iridium layer 25.
• the iridium layer 25 itself already acts as a protective layer, since iridium is at least partially oxidized under the SBT process conditions (about 800 ° C., oxygen-containing atmosphere) and thereby impedes oxygen diffusion.
• a further electrode 50 is deposited over the entire surface of the SBT layer 45. Together with the lower electrode 15 and the SBT layer 45, the further electrode 50 forms the ferroelectric storage capacitor 5.
• the platinum layer 30 also covers the side regions of the layer stack consisting of the barrier layer 35, the iridium oxide layer 20 and the iridium layer 25, so that the SBT layer 45 has no direct contact with the barrier layer 35.
• the entire interface of the lower electrode 15 with the SBT layer 45 is formed by the platinum layer 30, and thereby the interface properties and the storage properties of the SBT layer 45 are improved.
• FIG. 3 Another structure is shown in FIG. 3.
• the barrier layer 35 is formed only in the region of the contact hole 40, so that the barrier layer 35 is completely covered by the iridium oxide layer 20.
• the barrier layer 35 is completely protected against oxidation during the SBT deposition.
• Iridiumoxidtik 20 and the iridium layer 25 are performed to improve the capacitor properties.
• a sputter reactor 55 is schematically shown here, which has a substrate carrier 60 and a target holder 65, which simultaneously serve as cathode or anode.
• a silicon wafer 70 is located on the substrate carrier 60, which further represents the substrate 10.
• An iridium disk 75 with hafnium disks 80 placed thereon is attached to the target holder 65 arranged opposite the silicon wafer 70. These disks together represent the common source during the sputtering process. The proportion of the deposited hafnium can be adjusted by selecting the disk size of the hafnium disk.
• Hafnium and iridium are knocked out of the respective sources together by the argon plasma excited in the sputter reactor 55 and applied to the silicon wafer 70 as a mixture. It is also possible to replace the iridium disk 75 with an iridium oxide disk.
• the latter can be heated by a heater attached underneath the wafer.
• Favorable temperatures are in the range of 200 ° to 500 ° C.

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• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Computer Hardware Design (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Semiconductor Memories (AREA)
• Television Systems (AREA)
• Picture Signal Circuits (AREA)

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• 1998
  • 1998-12-10 DE DE19857039A patent/DE19857039A1/de not_active Withdrawn
• 1999
  • 1999-12-01 JP JP2000587359A patent/JP2002532872A/ja active Pending
  • 1999-12-01 CN CNB998161349A patent/CN1179396C/zh not_active Expired - Fee Related
  • 1999-12-01 EP EP99964386A patent/EP1149408A1/de not_active Withdrawn
  • 1999-12-01 KR KR1020017007231A patent/KR20010080742A/ko active IP Right Grant
  • 1999-12-01 WO PCT/DE1999/003832 patent/WO2000034988A1/de not_active Application Discontinuation
  • 1999-12-09 US US09/458,219 patent/US6377311B1/en not_active Expired - Fee Related
• 2001
  • 2001-06-11 US US09/878,735 patent/US20020017676A1/en not_active Abandoned

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