Novel stacked capacitor technology for 1 Gbit DRAMs with CVD-(Ba,Sr)TiO/sub 3/ thin films on a thick storage node of Ru

Yuuki, Akimasa; Yamamuka, Mikio; Makita, Tetsuro; Horikawa, Tsuyoshi; Shibano, Teruo; Hirano, N.; Maeda, Hiroaki; Mikami, Naohiko; Ono, Ken; Ogata, Hidenori; Abe, Haruhiko

doi:10.1109/iedm.1995.497195

Cited by 35 publications

(26 citation statements)

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“…Despite the reported differences in work functions, the leakage current of sputtered BST on Ru bottom electrodes is similar to that ofBST deposited on Pt bottom electrodes [94]. Films of BST with low leakage current densities have been achieved on patterned Pt [35,95,96], Ru [76,97] and RU02 [17,98].…”

Section: Leakage Currentmentioning

confidence: 84%

“…MOCVD B~T deposited on patterned Ru electrodes as described in Figure 22 using the 2 deposition step process has very similar electrical properties to planar [76]. The patterned Ru electrode should have increased the area by a factor of 1.7 and the corresponding capacitance increased by 1.6 (60 fF/Ilm2 to 92 fF/llm2) [76].…”

Section: Properties Of Mocvd Bst On 3d Structuresmentioning

confidence: 98%

“…Storage nodes were 0.24 11m wide, 0.6 11m long and 0.15 11m high each spaced 0.14 11m apart. Table 9: Capacitance at OV and leakage current at IV of BST deposited using 2 step deposition process on planar capacitors versus patterned Ru capacitors as described in Figure 23 [76]. S-N pattern increased area by factor of 1.7 but the capacitance increased by only 1.6.…”

Section: Properties Of Mocvd Bst On 3d Structuresmentioning

confidence: 98%

“…The conformality was not good with 85 nm BST on top and 34 nm on the sidewall. The capacitance of the 34 nm thick BST on the sidewall was calculated to be 53 fF/Ilm2 (teq = 0.65 nm) by measuring capacitance versus sidewall area [76]. The leakage current of ST on patterned RU02 electrodes was comparable with planar RU02 electrodes [17,78].…”

Section: Properties Of Mocvd Bst On 3d Structuresmentioning

confidence: 99%

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(Ba,Sr)TiO3 Thin Films for Dram’s

Summerfelt

1997

Thin Film Ferroelectric Materials and Devices

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Section: Leakage Currentmentioning

confidence: 84%

Section: Properties Of Mocvd Bst On 3d Structuresmentioning

confidence: 98%

Section: Properties Of Mocvd Bst On 3d Structuresmentioning

confidence: 98%

Section: Properties Of Mocvd Bst On 3d Structuresmentioning

confidence: 99%

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(Ba,Sr)TiO3 Thin Films for Dram’s

Summerfelt

1997

Thin Film Ferroelectric Materials and Devices

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“…[1][2][3][4][5] Chemical vapor deposition ͑CVD͒ has been known as the most promising method for fabricating high-quality BST films for DRAM devices where conformal coverage over complex topography is required. [6][7][8][9][10][11] A key to a successful CVD process is the availability of suitable precursors with sufficient volatility and stability. However, developing such precursors for BST films has been challenging due to the low volatility of the barium and strontium compounds stemming from their tendency to oligomerize.…”

mentioning

confidence: 99%

Low-Temperature Growth of Highly Crystalline (Ba, Sr)TiO[sub 3] Films by CLCB Method

Kang

Park

Kim

et al. 2004

Electrochem. Solid-State Lett.

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High-quality barium strontium titanate ͑BST͒ thin films were fabricated using charged liquid cluster beam ͑CLCB͒ method. The X-ray diffraction patterns of the as-deposited BST films indicated that the perovskite phase appeared at 450°C without any intermediate phase and high film crystallinity was achieved at 500°C. The Ba:Sr:Ti ratio in the precursor solution was transferred to the deposited film without any loss. The crystallinity, dielectric constant, dissipation factor, and leakage current density were measured and compared for the as-deposited films prepared at 500°C and the films deposited at 400°C and postannealed at 700°C. © 2004 The Electrochemical Society. ͓DOI: 10.1149/1.1809551͔ All rights reserved. Barium strontium titanate ͑BST͒ thin films have attracted much attention due to their potential applications in the dynamic random access memory ͑DRAM͒ and tunable microwave devices, which derive from their high dielectric constant, low leakage current density, and low dielectric loss and high tunability at room temperature.1-5 Chemical vapor deposition ͑CVD͒ has been known as the most promising method for fabricating high-quality BST films for DRAM devices where conformal coverage over complex topography is required.6-11 A key to a successful CVD process is the availability of suitable precursors with sufficient volatility and stability. However, developing such precursors for BST films has been challenging due to the low volatility of the barium and strontium compounds stemming from their tendency to oligomerize. Thus, the control on film stoichiometry is, in general, problematic. In addition, the films deposited by CVD require high-temperature post-annealing processes under O 2 ambience to obtain perovskite phase, which would cause the oxidation of poly-silicon at the interface of ULSI.12-14 With sol-gel processing or chemical solution deposition methods, which require no precursor volatility, the control of film stoichiometry is facile. [15][16][17][18][19][20][21][22][23][24] However, in these cases the formation of intermediate phase has been commonly observed and hightemperature postannealing processes are required to obtain perovskite phase. Besides, problems such as cracks in the deposited films and low throughput arise when the precursor materials are applied onto the substrates using conventional spin-coating technique.Herein, we report the growth of BST thin films by the charged liquid cluster beam ͑CLCB͒ method in an effort to circumvent the problems in the above-mentioned chemical processes. The deposited BST films exhibited smooth and dense surface morphology with good electrical properties. The Ba:Sr:Ti ratio in the precursor solution was preserved in the deposited films.The CLCB method is a novel thin-film deposition method in which flow-limited field-injection electrostatic spraying ͑FFESS͒ is invoked to produce charged nanodrops of a precursor solution. 25,26 These charged nanodrops are subsequently accelerated toward a heated substrate for film deposition. Detailed descriptions of the ...

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Liquid source chemical vapor deposition of high-dielectric-constant (Ba, Sr)TiO3 films

et al. 1998

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High‐dielectric‐constant (Ba, Sr)TiO3 [BST] films were deposited by the liquid source chemical vapor deposition (CVD) method. The system consisted of a single‐wafer, low‐pressure thermal CVD reactor, a vaporizer for liquid source materials, and a shower‐type gas nozzle head, giving stable BST film deposition on a 6‐in. diam. substrate with uniform thickness and uniform chemical composition ratio. The source materials employed were Ba(DPM)2, Sr(DPM)2, and TiO(DPM)2 dissolved in tetrahydrofuran (THF), resulting in conformal step coverage of BST films at lowered substrate temperatures, where DPM denotes dipivaloylmethanate. Moreover, the two‐step deposition technique was developed to restart protrusions formed on BST film surfaces at low temperatures, where the BST films consisted of a buffer layer and a main layer; the buffer layer was a layer about 60 Å thick of CVD‐BST film annealed in N2. Thus, the two‐step CVD deposition of BST films on Pt and Ru electrodes achieved an equivalent SiO2 thickness of teq ∼ 0.5 nm, a leakage current of JL ∼ 1.0 × 10−8 A/cm2 (at +1.1 V), and a dielectric loss of tan δ ∼ 0.01 at a total film thickness of 250 Å, along with conformal coverage of 80% for a trench with an aspect ratio of 0.65. Then, for BST films deposited on patterned electrodes 0.24 μm wide, 0.60 μm deep, and 0.15 μm high (each spaced by 0.14 μm), the capacitance was demonstrated to be increased without significant deterioration of the leakage current: the capacitance was increased in comparison with that for films on flat electrodes, by a factor corresponding to the increase in surface area due to sidewalls of storage‐node‐like pattern features. This capacitance increase reflects the most characteristic advantage of CVD, an excellent step coverage on microscopic pattern features. These electrical properties satisfy the specifications for capacitors for Gb‐scale dynamic random access memories (DRAMs), giving a storage capacitance of more than 25 fF/cell for a stacked capacitor having a storage node 0.2 to 0.3 μm high. © 1998 Scripta Technica, Electr Eng Jpn, 125(1): 47–54, 1998

show abstract

Novel stacked capacitor technology for 1 Gbit DRAMs with CVD-(Ba,Sr)TiO/sub 3/ thin films on a thick storage node of Ru

Cited by 35 publications

References 1 publication

(Ba,Sr)TiO3 Thin Films for Dram’s

(Ba,Sr)TiO3 Thin Films for Dram’s

Low-Temperature Growth of Highly Crystalline (Ba, Sr)TiO[sub 3] Films by CLCB Method

Liquid source chemical vapor deposition of high-dielectric-constant (Ba, Sr)TiO3 films

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