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

Definitions

• Microelectronic structure process for its production and its use in a memory cell.
• the invention relates to an microelectronic structure with a semiconductor structure, a barrier structure, an electrode structure and a dielectric structure made of a high-epsilon material. Such structures are used in particular as part of a capacitor.
• high-epsilon materials are used as a dielectric for capacitor structures. Such capacitors are used in particular as a storage capacitor or as part of a sensor element. Dielectric materials that have a dielectric constant ⁇ > 10 are referred to as high-epsilon material.
• the high-epsilon materials include paraelectric and ferroelectric materials.
• banum strontium titanate (BST) and strontium bismuth tantalate (SBT) are examined with regard to their use as a storage dielectric in a storage capacitor.
• the deposition of high-epsilon materials is usually carried out by metal-organic deposition in MOCVD (metal organic chemical vapor deposition) or MOD (metal organic deposition) processes, which are carried out at high temperatures in an oxygen-containing atmosphere.
• MOCVD metal organic chemical vapor deposition
• MOD metal organic deposition
• post-heating in oxygen is also necessary, which is carried out at BST at 550 ° C.
• TaSiN is to be used.
• additional equipment with expensive targets is he ⁇ conducive for the deposition of these materials.
• the invention is based on the problem to provide a micro-electro- ⁇ African structure with a semiconductor structure, a barrier structure, an electrode structure and a dielectric structure of a high-epsilon material, satisfying the requirements in the preparation of a storage capacitor and which can be manufactured without expensive equipment.
• the microelectronic structure has an electrode structure which has a tensile mechanical layer tension.
• the term stress is also used by experts for mechanical layer tension.
• the invention makes it Take advantage of the knowledge that high-epsilon materials deposited at high temperatures have a tensile layer tension.
• the invention makes use of the knowledge that the layer voltage of the electrode structure determines the total layer voltage of the electrode structure and the barrier structure. Because the electrode structure has a tensile layer voltage in the structure according to the invention, that is to say the layer voltage is greater than 0 Pa and the structure bulges away from the base at the edge of the structure, the dielectric structure and the base on which this creates a similar layer tension. This avoids a change in the layer voltage due to the application of the dielectric structure. Such a change in the layer voltage is responsible for the detachment of the electrode structure from the barrier structure in the known method and for the oxidation of the barrier structure in a known method.
• the dielectric structure can be formed from any high-epsilon material.
• the dielectric structure comprises barium strontium titanate (BST), strontium bismuth tantalate (SBT), lead zirconium titanate (PZT) or the like.
• the electrode structure contains platinum, which is widely used as an electrode material in connection with high-epsilon materials because of its reaction behavior.
• the platinum electrode structure with a specific resistance in the range between 10.5 and 13 ⁇ cm is preferably used. It has been shown that platinum with a specific resistance in this range additionally has a diffusion effect for oxygen. This is probably due to the higher density of the platinum. This diffusion barrier effect makes the underlying one Barrier structure additionally protected against oxidation during the deposition of the dielectric layer.
• the platm m of the electrode structure preferably has an average grain size between 60 and 100 nm. In this large area of the medium grain size, Platm has a sharp [111] texture, which has proven to be advantageous for the quality of the dielectric structure deposited thereon.
• the barrier structure in such a way that it contains a titanium layer and a titanium nitride layer, since these materials are common and well investigated as semiconductor materials in semiconductor technology.
• the titanium nitride layer preferably has a specific resistance in the range between 70 and 200 ⁇ cm. This reduces the layer resistance of the barrier structure and the electrode structure.
• the barrier structure preferably has a layer tension> -200 MPa, so that the combination of barrier structure and electrode structure has a tensile layer tension. It is particularly advantageous if the layer tension of the barrier structure is> 200 MPa, since the barrier structure then also has a tensile layer tension.
• the semiconductor structure preferably contains silicon, the barrier structure titanium nitride and titanium, the titanium layer having a thickness between 10 and 40 nm and the titanium layer having a thickness between 80 and 200 nm.
• the electron structure contains platm and has a thickness between 50 and 200 nm.
• the dielectric structure has BST and a thickness between 8 and 50 nm.
• the dielectric structure contains another high-epsilon material, in particular lead-zirconium-titanate or strontium-bismuth-tantalate.
• the materials of the barrier structure and the electrode structure are adapted to the material of the respective dielectric structure.
• the electrode structure is formed by sputtering platm at a sputtering temperature of at least 200 ° C. It has been shown that the mechanical layer tension of the electrode structure is essentially a function of the deposition temperature. When platinum is deposited by sputtering at a sputtering temperature of at least 200 ° C., the mechanical layer tension, for which the term stress is often used in the specialist literature, is tensile.
• the sputtering temperature for the deposition of the electrode structure from platinum is preferably chosen between 450 and 550 ° C. It has been shown that, at this higher deposition temperature, a lower layer resistance of the platinum, a larger average grain size of the platinum and a pronounced [111] layer texture are additionally achieved. In addition, it was observed that platinum sputtered at a higher temperature is a better diffusion camera for oxygen and thus more effectively protects the underlying barrier structure against oxidation during the deposition of the dielectric structure.
• the sputtering power is set in the range between 0.5 and 2 kW and the sputtering pressure in the range between 1 and 5 mTorr.
• the barrier layer is preferably formed from a titanium layer and a titanium nitride layer.
• the titanium nitride layer is formed by sputtering in an atmosphere with at least 70 percent nitrogen.
• the nitrogen content is determined as the ratio of the gas flows in standard cubic centimeters (sccm).
• a gas mixture of argon and nitrogen is preferably used for sputtering the titanium nitride.
• the pressure is preferably between 5 and 15 mTorr. It has been shown that the oxidability of the barrier structure is reduced by the high nitrogen content m in the sputtering atmosphere.
• the titanium nitride layer is preferably deposited at temperatures between 400 and 500 ° C. and a nitrogen content of 80 percent in the sputtering atmosphere. This further reduces the oxidizability of the barrier structure. In addition, the mechanical layer stresses in the barrier structure become zero or slightly tensile.
• the microelectronic structure can advantageously be used as part of a storage capacitor in a memory cell, the electrode structure representing a first electrode of the storage capacitor.
• the storage capacitor also has a second electrode, which is arranged on the side of the dielectric structure opposite the first electrode.
• microelectronic structure can be used as part of a sensor or actuator.
• FIG. 1 shows a section through a memory cell with a storage capacitor, which has a microelectronic structure with a semiconductor structure, a bar- structure, an electrode structure and a dielectric structure.
• Figure 2 shows the relationship between sputtering temperature and mechanical layer tension of a platinum layer.
• FIG. 3 shows the relationship between the mechanical layer stress and the sputtering temperature of a Pt / TiN / Ti stack.
• Em semiconductor substrate 1 contains a memory cell arrangement with a plurality of memory cells.
• Each of the memory cells has a selection transistor with two source / dram regions 2, a gate oxide region 3, a gate electrode 4 and a storage capacitor with an electrode structure 5, a dielectric structure 6 and an upper electrode structure 7 (see FIG. 1).
• the gate electrode 4 is connected to a word line
• one of the source / dram regions 2 is connected to a bit line 8.
• An intermediate oxide layer 9 covers the selection transistor.
• a contact hole is provided in the intermediate oxide layer 9, which extends to the other source / dram region 2, which is not connected to the bit line 8, and which is filled with a semiconductor structure 10.
• the semiconductor structure 10 contains doped polysilicon.
• the barner structure 11 comprises a titanium layer 111 and a titanium nitride layer 112 arranged above it.
• the titanium layer 111 has a thickness of 20 nm.
• the titanium nitride layer 112 has a thickness of 100 nm.
• the barrier structure 11 is electrically conductive. Together with the semiconductor structure 10 made of n + -doped polysilicon with a dopant concentration of 5 xl ⁇ l9 k ls 5 x it establishes an electrical connection between the Source / Dram Geb ⁇ et 2 and the lower electrode structure 5 of the storage capacitor.
• the lower electrode structure 5 of the storage capacitor has a thickness of 100 nm. It contains platinum.
• the dielectric structure 6 contains BST and has a thickness of 50 nm.
• the upper electrode structure 7 contains platm and has a thickness of 100 nm.
• a 20 nm thick titanium layer 111 is first deposited m Ar at a pressure of 1 to 5 mTorr and a sputtering power between 1 and 5 kW. Then, in a reactive sputtering process, a gas mixture of argon and nitrogen at a pressure between 5 and 15 mTorr, a sputtering power of 6.5 kW and a nitrogen content of 80 percent in the sputtering atmosphere, the 100 nm thick titanium nitride layer 112 is deposited. The temperature during the deposition is 400 to 500 ° C. With these deposition insulation, the mechanical layer tension of the barrier structure 11 is zero to slightly tensile.
• these deposition conditions mean that the nitrogen content m of the titanium nitride layer 112 with a stoichiometry N: T ⁇ > 1.
• the barrier structure 11 has a specific sheet resistance of 90 ⁇ cm.
• the lower electrode structure 5 is deposited from platm in a sputtering process at a deposition temperature between 450 and 550 ° C., a pressure of 3.5 mTorr and a sputtering power of 0.5 kW. With these deposition parameters, the lower electrode structure 5 has a tensile layer tension. Furthermore, the lower electrode structure 5 has a specific resistance of 11 ⁇ cm. It has a sharp [111] texture. Due to the separation conditions, the lower electrode structure 5 also shows a good diffusion barrier effect for oxygen.
• FIG. 2 shows the dependence of the mechanical layer tension, also called stress, on a 100 nm thick platinum layer, which was deposited with a sputtering power of 0.5 kW, a gas flow of 65 sccm argon and a sputtering pressure of 3.5 mTorr, m Dependence of the temperature T m ° C shown. It shows that the mechanical layer tension S> 0 becomes from a deposition temperature of about 200 ° C. This means that the layer has a tensile layer tension.
• the layer tension S is determined as follows: The shape or position of the wafer between the capacitor plates is determined capacitively or by means of a laser at various points on the wafer. By comparing with a plan
• Layer voltage S and the sputtering temperature T are shown for a stack which has a 20 nm thick titanium layer, a 100 nm thick titanium nitride layer arranged thereon and a 100 nm thick platinum layer arranged thereon.
• Curve 3a shows the relationship in the event that the titanium layer and titanium nitride layer are deposited at a deposition temperature of 450 ° C., while the deposition temperature of the platinum layer varies.
• Curve 3b shows the relationship in the event that the platinum layer is deposited at 500 ° C. and the deposition temperature of the titanium nitride layer and the titanium layer varies.
• the mechanical layer stress S of the platinum layer is a function of the deposition temperature of the platinum layer. This means that the resulting layer tension of the stack (see FIG. 3) is essentially determined by the layer tension of the platinum layer.

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• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Computer Hardware Design (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Semiconductor Memories (AREA)
• Semiconductor Integrated Circuits (AREA)
• Electrodes Of Semiconductors (AREA)

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• 1999
  • 1999-07-20 TW TW088112279A patent/TW457703B/zh active
  • 1999-08-02 CN CNB998105082A patent/CN1165974C/zh not_active Expired - Fee Related
  • 1999-08-02 KR KR10-2001-7002709A patent/KR100499429B1/ko not_active IP Right Cessation
  • 1999-08-02 JP JP2000568116A patent/JP2002524850A/ja active Pending
  • 1999-08-02 WO PCT/DE1999/002414 patent/WO2000013224A1/de not_active Application Discontinuation
  • 1999-08-02 EP EP99952272A patent/EP1114451A1/de not_active Withdrawn
• 2001
  • 2001-02-28 US US09/796,208 patent/US6670668B2/en not_active Expired - Lifetime

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