- Nano Express
- Open Access
Surface scattering mechanisms of tantalum nitride thin film resistor
Nanoscale Research Letters volume 9, Article number: 177 (2014)
In this letter, we utilize an electrical analysis method to develop a TaN thin film resistor with a stricter spec and near-zero temperature coefficient of resistance (TCR) for car-used electronic applications. Simultaneously, we also propose a physical mechanism mode to explain the origin of near-zero TCR for the TaN thin film resistor (TFR). Through current fitting, the carrier conduction mechanism of the TaN TFR changes from hopping to surface scattering and finally to ohmic conduction for different TaN TFRs with different TaN microstructures. Experimental data of current–voltage measurement under successive increasing temperature confirm the conduction mechanism transition. A model of TaN grain boundary isolation ability is eventually proposed to influence the carrier transport in the TaN thin film resistor, which causes different current conduction mechanisms.
With portable electronic devices being popular worldwide, the integration of memory[1–38], display[39–45], and IC circuits has become important in the recent years. Especially, a high-accuracy thin film resistor (TFR) needs to make a light, thin, short, and small product with a decrease of tolerance for electronic and optical device applications. Tantalum nitride is a mechanically hard, chemically inner, and corrosion-resistant material and has good shock/heat resistance properties[47–50]. These properties make the material attractive for many industrial applications for use as TFR material in portable electronic products. A low or near-zero temperature coefficient of resistance (TCR) is also required for the purpose of high reliability in TFR. In order to make the TFR conform to the requirement of a stricter spec for car-used electronic applications, it is a big challenge to develop a material with near-zero TCR for a large temperature region.
In our research, a TaN thin film resistor chip was fabricated to do the current–voltage measurement and analysis. Different TaN films with different manufacture processes were applied so as to analyze characteristics of the TaN TFR. Conduction current fitting together with varied-temperature current–voltage measurement data was thoroughly investigated, from which current conduction mechanisms were determined. Finally, the TaN grain boundary isolation model was proposed to explain the current conduction mechanisms under different TaN thin film deposition conditions.
The experimental thin film resistor chips (Figure 1) were prepared as follows: Firstly, the conductor silver material was printed on an alumina substrate. Then, TaN films with a thickness of about 150 nm were deposited on the silver-printed substrate by DC sputtering with Ta target in the Ar/N2 mixed gas ambient. The sputtering power was fixed at a DC power of 500 W. After that, all specimens were annealed in an oven with a working pressure of 1e-5 Torr. The annealing process was set at different temperatures to form the TaN films with different TCR values. Finally, the thin film resistor chips were fabricated by capping a termination conductive layer through electroplating process. In order to conduct the electrical measurement and analysis of the TaN thin film resistor, a snake-type pattern (the photo image of Figure 1) was realized by the laser trimming process using a green laser to obtain higher resistance. The entire electrical measurements of devices were performed using an Agilent B1500 semiconductor parameter analyzer (Agilent Technologies Inc., Santa Clara, CA, USA).
Results and discussion
DC sweeping was applied to investigate the properties of current–voltage of the TaN thin film resistor. In our experiment, we mainly focused on the current conduction mechanism in the TaN resistive layer. In order to analyze its characteristics, different TaN resistive layers with different polarities of the TCR value were employed: different TaN layers including TCR larger than zero, TCR smaller than zero, and TCR equal to zero. Through conduction current fitting, a noticeable transition of carrier conduction mechanism was found, which gradually changed from hopping conduction to surface scattering and finally to ohmic conduction with the increase of the TCR value of the TaN TFR shown in Figure 2.
To testify the validity of fitting, varied-temperature I-V measurement was applied and the results are shown in Figure 2. The TCR values in Figure 2 were <0, =0, and >0, respectively. It can be observed from the experimental data that the current of TCR < 0 was directly proportional to temperature, while the current of TCR > 0 was the opposite. The current of TCR = 0 was independent of temperature. All the experimental data were in accordance with their corresponding conduction mechanism.
From the experimental results, a carrier conduction model of the TaN resistive layer was proposed (Figure 3). As the oxidation of TaN grain boundary was the main reason for the change of carrier transport mechanism in the TaN resistive layer, it is easier to increase the TCR value with the increase of TaN oxidation degree. Thus, the level of oxidation in the grain boundary of TaN should be controlled carefully to achieve the target of TCR = 0. A TaN resistive layer with TCR < 0 was greatly oxidized so that the TaN grain was isolated completely, which resulted in carrier hopping conduction owing to the discrete TaN precipitates (left-side diagram of Figure 3). With the decreasing oxidation of the TaN grain boundary, the carrier conduction will be limited between two TaN grain boundaries and the surface scattering became easier for those discrete TaN grains to join and merge with each other, from which relative complete filaments can be formed, as shown in the middle diagram of Figure 3. Because of the formation of a smoother carrier conduction path and the independence of temperature, the carrier conduction mechanism transformed from hopping conduction to surface scattering (Figure 2). However, the filament is not thick enough for numerous carriers to conduct through it, which leads to the crowding of carriers. The carriers have to be forced out from the restricted filament which is also the reason why we can find space scattering conduction. Meanwhile, the measurement result of Figure 2 also complies with surface scattering mechanism as current is independent with temperature. If the level of oxidation in the TaN film was decreased, ohmic conduction mechanism will dominate due to the formation of a thicker and more continuous filament (right-side diagram of Figure 3). The fitting result of ohmic conduction is shown in Figure 2.
In conclusion, the carrier conduction mechanisms of TaN thin film resistors with different TCR values are thoroughly investigated. With the increase of the TCR value, the conduction mechanism transforms from hopping conduction to surface scattering and finally to ohmic conduction. The transition of the carrier conduction mechanism is explained by our model, from which the relationship of the TCR value and oxidation degree of the TaN thin film resistor can be better understood. Based on the relationship, the near-zero TCR TaN resistive layer can be fabricated by controlling the level of oxidation and can be demonstrated by electrical current measurement and fitting analysis.
Zhu CX, Huo ZL, Xu ZG, Zhang MH, Wang Q, Liu J, Long S, Liu M: Performance enhancement of multilevel cell nonvolatile memory by using a bandgap engineered high-kappa trapping layer. Appl Phys Lett 2010, 97: 253503. 10.1063/1.3531559
Chang TC, Jian FY, Chen SC, Tsai YT: Developments in nanocrystal memory. Mater Today 2011, 14(12):608. 10.1016/S1369-7021(11)70302-9
Syu YE, Chang TC, Tsai TM, Hung YC, Chang KC, Tsai MJ, Kao MJ, Sze SM: Redox reaction switching mechanism in RRAM device with Pt/CoSiOX/TiN structure. IEEE Electron Device Lett 2011, 32(4):545–547.
Liu M, Abid Z, Wang W, He X, Liu Q, Guan W: Multilevel resistive switching with ionic and metallic filaments. Appl Phys Lett 2009, 94: 233106. 10.1063/1.3151822
Chen MC, Chang TC, Tsai CT, Huang SY, Chen SC, Hu CW, Sze SM, Tsai MJ: Influence of electrode material on the resistive memory switching property of indium gallium zinc oxide thin films. Appl Phys Lett 2010, 96: 262110. 10.1063/1.3456379
Chu TJ, Tsai TM, Chang TC, Chang KC, Zhang R, Chen KH, Chen JH, Young TF, Huang JW, Lou JC, Chen MC, Huang SY, Chen HL, Syu YE, Bao DH, Sze SM: Tri-resistive switching behavior of hydrogen induced resistance random access memory. IEEE Electron Device Lett 2014, 35(2):217–219.
Lin CC, Kuo Y: Memory functions of nanocrystalline cadmium selenide embedded ZrHfO high-k dielectric stack. J Appl Phys 2014, 115: 084113. 10.1063/1.4867215
Lin CC, Kuo Y, Zhang S: Nonvolatile memory devices with AlOx embedded Zr-doped HfO2 high-k gate dielectric stack. J Vac Sci Technol B 2014, 32(3):1–03D116.
Chang KC, Chen JH, Tsai TM, Chang TC, Huang SY, Zhang R, Chen KH, Syu YE, Chang GW, Chu TJ, Liu GR, Su YT, Chen MC, Pan JH, Liao KH, Tai YH, Young TF, Sze SM, Ai CF, Wang MC, Huang JW: Improvement mechanism of resistance random access memory with supercritical CO2 fluid treatment. J Supercrit Fluids 2014, 85: 183–189.
Su YT, Chang KC, Chang TC, Tsai TM, Zhang R, Lou JC, Chen JH, Young TF, Chen KH, Tseng BH, Shih CC, Yang YL, Chen MC, Chu TJ, Pan CH, Syu YE, Sze SM: Characteristics of hafnium oxide resistance random access memory with different setting compliance current. Appl Phys Lett 2013, 103(16):163502. 10.1063/1.4825104
Long SB, Lian XJ, Cagli C, Cartoixa X, Rurali R, Miranda E, Jimenez D, Perniola L, Liu M, Sune J: Quantum-size effects in hafnium-oxide resistive switching. Appl Phys Lett 2013, 102(18):183505. 10.1063/1.4802265
Long SB, Perniola L, Cagli C, Buckley J, Lian XJ, Miranda E, Pan F, Liu M, Sune J: Voltage and power-controlled regimes in the progressive unipolar RESET transition of HfO2-based RRAM. Sci Rep 2013, 3: 2929.
Chu TJ, Chang TC, Tsai TM, Wu HH, Chen JH, Chang KC, Young TF, Chen KH, Syu YE, Chang GW, Chang YF, Chen MC, Lou JH, Pan JH, Chen JY, Tai YH, Ye C, Wang H, Sze SM: Charge quantity influence on resistance switching characteristic during forming process. IEEE Electron Device Lett 2013, 34(4):502–504.
Chang KC, Zhang R, Chang TC, Tsai TM, Lou JC, Chen JH, Young TF, Chen MC, Yang YL, Pan YC, Chang GW, Chu TJ, Shih CC, Chen JY, Pan CH, Su YT, Syu YE, Tai YH, Sze SM: Origin of hopping conduction in graphene-oxide-doped silicon oxide resistance random access memory devices. IEEE Electron Device Lett 2013, 34(5):677.
Long SB, Lian XJ, Cagli C, Perniola L, Miranda E, Liu M, Sune J: A model for the set statistics of RRAM inspired in the percolation model of oxide breakdown. IEEE Electron Device Lett 2013, 34(8):999–1001.
Chang KC, Huang JW, Chang TC, Tsai TM, Chen KH, Young TF, Chen JH, Zhang R, Lou JC, Huang SY, Pan YC, Huang HC, Syu YE, Gan DS, Bao DH, Sze SM: Space electric field concentrated effect for Zr: SiO2 RRAM devices using porous SiO2 buffer layer. Nanoscale Res Lett 2013, 8: 523. 10.1186/1556-276X-8-523
Guan WH, Long S, Jia R, Liu M: Nonvolatile resistive switching memory utilizing gold nanocrystals embedded in zirconium oxide. Appl Phys Lett 2007, 91: 062111. 10.1063/1.2760156
Zhang R, Chang KC, Chang TC, Tsai TM, Chen KH, Lou JC, Chen JH, Young TF, Shih CC, Yang YL, Pan YC, Chu TJ, Huang SY, Pan CH, Su YT, Syu YE, Sze SM: High performance of graphene oxide-doped silicon oxide-based resistance random access memory. Nanoscale Res Lett 2013, 8: 497. 10.1186/1556-276X-8-497
Syu YE, Chang TC, Tsai TM, Chang GW, Chang KC, Lou JH, Tai YH, Tsai MJ, Wang YL, Sze SM: Asymmetric carrier conduction mechanism by tip electric field in WSiOX resistance switching device. IEEE Electron Device Lett 2012, 33(3):342–344.
Chang KC, Tsai TM, Zhang R, Chang TC, Chen KH, Chen JH, Young TF, Lou JC, Chu TJ, Shih CC, Pan JH, Su YT, Syu YE, Tung CW, Chen MC, Wu JJ, Hu Y, Sze SM: Electrical conduction mechanism of Zn: SiOx resistance random access memory with supercritical CO2 fluid process. Appl Phys Lett 2013, 103: 083509. 10.1063/1.4819162
Liu Q, Guan WH, Long SB, Jia R, Liu M, Chen J: Resistive switching memory effect of ZrO2 films with Zr + implanted. Appl Phys Lett 2008, 92: 012117. 10.1063/1.2832660
Tsai TM, Chang KC, Zhang R, Chang TC, Lou JC, Chen JH, Young TF, Tseng BH, Shih CC, Pan YC, Chen MC, Pan JH, Syu YE, Sze SM: Performance and characteristics of double layer porous silicon oxide resistance random access memory. Appl Phys Lett 2013, 102: 253509. 10.1063/1.4812474
Lin CC, Kuo Y: Temperature effects on nanocrystalline molybdenum oxide embedded ZrHfO high-k nonvolatile memory functions. ECS J Solid State Sci Technol 2013, 2(1):Q16.
Syu YE, Chang TC, Lou JH, Tsai TM, Chang KC, Tsai MJ, Wang YL, Liu M, Simon MS: Atomic-level quantized reaction of HfOx memristor. Appl Phys Lett 2013, 102: 172903. 10.1063/1.4802821
Chang KC, Pan CH, Chang TC, Tsai TM, Zhang R, Lou JC, Young TF, Chen JH, Shih CC, Chu TJ, Chen JY, Su YT, Jiang JP, Chen KH, Huang HC, Syu YE, Gan DS, Sze SM: Hopping effect of hydrogen-doped silicon oxide insert RRAM by supercritical CO2 fluid treatment. IEEE Electron Device Lett 2013, 34(5):617–619.
Long SB, Cagli C, Ielmini D, Liu M, Sune J: Analysis and modeling of resistive switching statistics. J App Phys 2012, 111(7):074508. 10.1063/1.3699369
Chang KC, Tsai TM, Chang TC, Wu HH, Chen KH, Chen JH, Young TF, Chu TJ, Chen JY, Pan CH, Su YT, Syu YE, Tung CW, Chang GW, Chen MC, Huang HC, Tai YH, Gan DS, Wu JJ, Hu Y, Sze SM: Low temperature improvement method on Zn: SiOx resistive random access memory devices. IEEE Electron Device Lett 2013, 34(4):511–513.
Wang Y, Liu Q, Long SB, Wang W, Wang Q, Zhang MH, Zhang S, Li YT, Zuo QY, Yang JH, Liu M: Investigation of resistive switching in Cu-doped HfO2 thin film for multilevel non-volatile memory applications. Nanotechnology 2010, 21: 045202. 10.1088/0957-4484/21/4/045202
Chang KC, Tsai TM, Chang TC, Wu HH, Chen JH, Syu YE, Chang GW, Chu TJ, Liu GR, Su YT, Chen MC, Pan JH, Chen JY, Tung CW, Huang HC, Tai YH, Gan DS, Sze SM: Characteristics and mechanisms of silicon oxide based resistance random access memory. IEEE Electron Device Lett 2013, 34(3):399–401.
Tsai TM, Chang KC, Chang TC, Chang GW, Syu YE, Su YT, Liu GR, Liao KH, Chen MC, Huang HC, Tai YH, Gan DS, Sze SM: Origin of hopping conduction in Sn-doped silicon oxide RRAM with supercritical CO2 fluid treatment. IEEE Electron Device Lett 2012, 33(12):1693–1695.
Tsai TM, Chang KC, Chang TC, Syu YE, Chuang SL, Chang GW, Liu GR, Chen MC, Huang HC, Liu SK, Tai YH, Gan DS, Yang YL, Young TF, Tseng BH, Chen KH, Tsai MJ, Ye C, Wang H, Sze SM: Bipolar resistive RAM characteristics induced by nickel incorporated into silicon oxide dielectrics for IC applications. IEEE Electron Device Lett 2012, 33(12):1696–1698.
Tsai TM, Chang KC, Chang TC, Syu YE, Liao KH, Tseng BH, Sze SM: Dehydroxyl effect of Sn-doped silicon oxide resistance random access memory with supercritical CO2 fluid treatment. Appl Phys Lett 2012, 101: 112906. 10.1063/1.4750235
Li YT, Long SB, Zhang MH, Liu Q, Zhang S, Wang Y, Zuo QY, Liu S, Liu M: Resistive switching properties of Au/ZrO2/Ag structure for low voltage nonvolatile memory applications. IEEE Electron Device Lett 2010, 31(2):117–119.
Chang KC, Tsai TM, Chang TC, Syu YE, Liao KH, Chuang SL, Li CH, Gan DS, Sze SM: The effect of silicon oxide based RRAM with tin doping. Electrochem Solid-State Lett 2012, 15(3):H65-H68. 10.1149/2.013203esl
Chang KC, Tsai TM, Chang TC, Syu YE, Wang C-C, Liu SK, Chuang SL, Li CH, Gan DS, Sze SM: Reducing operation current of Ni-doped silicon oxide resistance random access memory by supercritical CO2 fluid treatment. Appl Phys Lett 2011, 99(26):263501. 10.1063/1.3671991
Chen WR, Chang TC, Yeh JL, Sze SM, Chang CY: Reliability characteristics of NiSi nanocrystals embedded in oxide and nitride layers for nonvolatile memory application. Appl Phys Lett 2008, 92(15):152114. 10.1063/1.2905812
Tsai YT, Chang TC, Lin CC, Chen SC, Chen CW, Sze SM, Yeh FS, Tseng TY: Influence of nanocrystals on resistive switching characteristic in binary metal oxides memory devices. Electrochem Solid-State Lett 2011, 14(3):H135. 10.1149/1.3531843
Wang SY, Huang CW, Lee DY, Tseng TY, Chang TC: Multilevel resistive switching in Ti/CuxO/Pt memory devices. J Appl Phys 2010, 108(11):114110. 10.1063/1.3518514
Chen HB, Chang CY, Lu NH, Wu JJ, Han MH, Cheng YC, Wu YC: Characteristics of gate-all-around junctionless poly-Si TFTs with an ultrathin channel. IEEE Electron Device Lett 2013, 34(7):897–899.
Chen SC, Chang TC, Liu PT, Wu YC, Lin PS, Tseng BH, Shy JH, Sze SM, Chang CY, Lien CH: A novel nanowire channel poly-Si TFT functioning as transistor and nonvolatile SONOS memory. IEEE Electron Device Lett 2007, 28(9):809–811.
Tsai CT, Chang TC, Chen SC, Lo I, Tsao SW, Hung MC, Chang JJ, Wu CY, Huang CY: Influence of positive bias stress on N2O plasma improved InGaZnO thin film transistor. Appl Phys Lett 2010, 96: 242105. 10.1063/1.3453870
Chen TC, Chang TC, Tsai CT, Hsieh TY, Chen SC, Lin CS, Hung MC, Tu CH, Chang JJ, Chen PL: Behaviors of InGaZnO thin film transistor under illuminated positive gate-bias stress. Appl Phys Lett 2010, 97: 112104. 10.1063/1.3481676
Liu PT, Chou YT, Teng LF: Charge pumping method for photo-sensor application by using amorphous indium-zinc oxide thin film transistors. Appl Phys Lett 2009, 94(24):242101. 10.1063/1.3155507
Chung WF, Chang TC, Li HW, Chen CW, Chen YC, Chen SC, Tseng TY, Tai YH: Influence of H2O dipole on subthreshold swing of amorphous indium-gallium-zinc-oxide thin film transistors. Electrochem Solid-State Lett 2011, 14(3):H114. 10.1149/1.3526097
Huang SY, Chang TC, Chen MC, Chen SC, Tsai CT, Hung MC, Tu CH, Chen CH, Chang JJ, Liau WL: Effects of ambient atmosphere on electrical characteristics of Al2O3 passivated InGaZnO thin film transistors during positive-bias-temperature-stress operation. Electrochem Solid-State Lett 2011, 14(4):H177. 10.1149/1.3534828
Lin CC, Kuo Y: Improvement of zirconium-doped hafnium oxide high-k dielectric properties by adding molybdenum. J Vac Sci Technol B 2013, 31(3):030605–1. 10.1116/1.4802778
Lovejoy ML, Patrizi GA, Reger DJ, Barbour JC: Thin-film tantalum-nitride resistor technology for phosphite-based optoelectronics. Thin Solid Films 1996, 290–291: 513–517.
Riekkinen T, Molarius J, Laurila T, Nurmela A, Suni I, Kivilahti JK: Reactive sputter deposition and properties of TaxN thin films. Microelectron Eng 2002, 64: 289. 10.1016/S0167-9317(02)00801-8
Yuan ZL, Zhang DH, Li CY, Prasad K, Tan CM, Tang LJ: A new method for deposition of cubic Ta diffusion barrier for Cu metallization. Thin Solid Films 2003, 434: 126. 10.1016/S0040-6090(03)00532-7
Yang LY, Zhang DH, Li CY, Foo PD: Organic thin film transistor memory with gold nanocrystals embedded in polyimide gate dielectric. Thin Solid Films 2004, 462–463: 176.
Takagi S, Toriumi A, Iwase M, Tango H: On the universality of inversion layer mobility in Si MOSFET's: part I-effects of substrate impurity concentration. IEEE Trans Electron Device 1994, 41(12):2357–2362. 10.1109/16.337449
This work was performed at the National Science Council Core Facilities Laboratory for Nano-Science and Nano-Technology in the Kaohsiung-Pingtung area and was supported by the National Science Council of the Republic of China under Contract Nos. NSC-102-2120-M-110-001.
The authors declare that they have no competing interests.
HRC designed and set up the experimental procedure. YCC and TCC planned the experiments and agreed with the paper's publication. TMT revised the manuscript critically. KCC, TJC, and CCS conducted the electrical measurement of the devices. NCC fabricated the devices with the assistance of KYW. All authors read and approved the final manuscript.
About this article
Cite this article
Chen, HR., Chen, YC., Chang, TC. et al. Surface scattering mechanisms of tantalum nitride thin film resistor. Nanoscale Res Lett 9, 177 (2014). https://doi.org/10.1186/1556-276X-9-177
- Thin film resistor
- Temperature coefficient of resistance
- Surface scattering