Browsing by Author "Tsai, TM"

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CMP of low-k methylsilsesquiazane with oxygen plasma treatment for multilevel interconnect applications
(2004)
Chang, TC
;
Tsai, TM
;
Liu, PT
;
Chen, CW
;
Yan, ST
The effect of oxygen plasma treatment on methylsilsesquiazane (MSZ) dielectric was investigated for chemical mechanical planarization (CMP) process. Oxygen plasma treatment was implemented before CMP. Experimental results have shown that the polishing rate of MSZ film with O-2 plasma pretreatment is increased as much as two order of magnitude more than that of MSZ without O-2 plasma pretreatment. Moreover, the electrical properties of post-CMP MSZ are close to those of an as-cured MSZ. These results indicate that the modified surfaces resulting from O-2 plasma treatment increase the polishing rate of MSZ. After polishing, the MSZ film still maintains a low-k quality. (C) 2004 The Electrochemical Society.
CMP of ultra low-k material porous-polysilazane (PPSZ) for interconnect applications
(2004-01-30)
Chang, TC
;
Tsai, TM
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Liu, PT
;
Chen, CW
;
Yan, ST
In this article, we investigated the impact of chemical mechanical polishing (CMP) on an ultra low dielectric constant (ultra low-k) material Porous-Polysilazane (PPSZ) with slurries of metal polishing during interconnect manufacture process. Since the CMP processing of metals such as TaN and Cu are inevitable steps for interconnect fabrication, we have utilized two types of slurries (marked as TaN and Cu slurries) to evaluate their effects on the dielectric properties of PPSZ films. Electrical and material analyses have shown surface planarity and dielectric properties of PPSZ films will not be degraded during these metal CMP processes. This indicates that the ultra low-k PPSZ films are promising for inter-level dielectric (ILD) applications in ultra large-scale integrated circuits (ULSI) technology. (C) 2003 Elsevier B.V. All rights reserved.
Cu-penetration induced breakdown mechanism for a-SiCN
(2004-12-22)
Chen, CW
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Liu, PT
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Chang, TC
;
Yang, JH
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Tsai, TM
We have investigated the leakage mechanism of amorphous SiCN (a-SiCN) films after bias-temperature-stress (BTS) with Cu electrode. The leakage current became very large and breakdown due to the Cu ions penetration after strict BTS condition. The distribution profile of Cu penetration was depicted by SIMS spectrum. It is apparent that Cu ions penetrated into the a-SiCN film and even reached to the interface between a-SiCN/Si due to BTS. The Cu ions existing in a-SiCN would be taken as trap states and could enhance the carriers to transport. The main characteristics of post-breakdown a-SiCN followed the space-charge-limited current (SCLC) mechanism at 298 K. With decreasing the temperature to 100 K, the Fowler-Nordheim tunneling dominated the conduction in medium fields. However, electrons obeyed the SCLC again in high fields (>3.3 MV/cm) at 100 K. We purpose a physical model to interpret the leakage mechanism of breakdown a-SiCN films due to Cu ions. (C) 2004 Elsevier B.V. All rights reserved.
Dielectric characteristics of low-permittivity silicate using electron beam direct patterning for intermetal dielectric applications
(2003-11-17)
Liu, PT
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Chang, TC
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Tsai, TM
;
Lin, ZW
;
Chen, CW
A direct patterning technology of low-permittivity silicate-based polymer is investigated with electron-beam lithography for multilevel interconnections. The smallest feature size of 60 nm for damascene lines can be directly patterned in the silicate film. In this direct patterning, dielectric regions exposed by electron beam are crosslinked and form desirable patterns, while the others are dissolvable in an aqueous solution containing 2.38% tetramethylammonium hydroxide. With an optimum condition of electron-beam lithography, the electron-beam-irradiated silicate exhibits superior dielectric properties than that of the furnace-cured silicate film, due to minimizing the break of Si-H bonds and moisture uptake. The explanation is in agreement with the analyses of Fourier transform infrared spectroscopy and thermal desorption spectroscopy. (C) 2003 American Institute of Physics.
Direct Patterning of low-k hydrogen silsesquioxane using X-ray exposure technology
(2003-05-01)
Chang, TC
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Tsai, TM
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Liu, PT
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Mor, YS
;
Chen, CW
An inorganic low-k material, hydrogen silsesquioxane (HSQ), patterned directly using X-ray exposure technology was investigated. In conventional integrated circuit integration processes, photoresist (PR) stripping with O-2 plasma and wet chemical stripper are inevitable steps. However, dielectric degradation often occurs when low-k dielectrics undergo PR stripping processes. To overcome the integration issue X-ray direct patterning is proposed. In this technology, the dielectric regions illuminated by X-ray are cross-linked and form desired patterns, while the regions without X-ray illumination are dissolvable in the solvent of HSQ solution. An optical microscope image of an HSQ linear pattern was demonstrated for the first time to verify process feasibility. (C) 2003 The Electrochemical Society.
Direct Patterning of low-k hydrogen silsesquioxane using X-ray exposure technology (vol 6, pg G69, 2003)
(2003-07-01)
Chang, TC
;
Tsai, TM
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Liu, PT
;
Mor, YS
;
Chen, CW
Effective repair to ultra-low-k dielectric material (k-2.0) by hexamethyidisilazane treatment
(2002-07-01)
Mor, YS
;
Chang, TC
;
Liu, PT
;
Tsai, TM
;
Chen, CW
O-2 plasma ashing is commonly used to remove photoresist. The effect of O-2 plasma ashing on the porous organosilicate glass (CH3SiO1.5)(n), one of the spin-on materials, is investigated. O2 plasma can oxidize the methyl groups in porous organosilicate glass (POSG), which leads to the formation of Si-OH groups. The hydrophilic Si-OH groups will induce moisture uptake so that electrical degradation will occur in POSG film. Pure hexamethyldisilazane (HMDS) vapor (100% HMDS) can react with the Si-OH groups in POSG film. It converts hydrophilic Si-OH groups into hydrophobic Si-O-Si(CH3)(3) groups against moisture uptake. The leakage current density decreases by a factor of 2-3 and the dielectric constant decreases from 3.62 to 2.4 when O-2 plasma-damaged POSG undergoes HMDS treatment at 80degreesC for 15 min. Therefore, HMDS treatment is the effective technique to repair the electrical degradation to POSG film during photoresist stripping processing. (C) 2002 American Vacuum Society.
Effective strategy for porous organosilicate to suppress oxygen ashing damage
(2002-03-01)
Liu, PT
;
Chang, TC
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Mor, YS
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Chen, CW
;
Tsai, TM
Photoresist stripping with oxygen plasma ashing destroys numerous functional groups in porous organosilicate glasses (OSGs), This impact makes the porous OSG relatively hydrophilic and causes low-k dielectric degradation, To mitigate these issues, various strategies are investigated to enhance oxygen plasma resistance of the porous OSG. These include physical and chemical procedures. Both structural and electrical analyses are used to determine their efficiency. In addition, an optimum prescription that consists of H, plasma and chemical trimethylchlorosilane treatment is developed in this work. The enhancement of oxygen plasma resistance can provide the porous OSG for practical application in the multilevel interconnection. (C) 2002 The Electrochemical Society.
Effectiveness of NH3 plasma treatment in preventing wet stripper damage to low-k hydrogen silsesquioxane (HSQ)
(2001-12-01)
Chang, TC
;
Mor, YS
;
Liu, PT
;
Tsai, TM
;
Chen, CW
Wet stripper is commonly used to remove photoresist in IC integration processing. However, the high alkalinity of the wet stripper solution often leads to the hydrolysis of hydrogen silsesquioxane (HSQ) film and induces water uptake. As a result, both the leakage current and dielectric constant of HSQ increase. In this study, NH3 plasma treatment was applied to the HSQ film to form a thin nitrogen-containing layer on the HSQ surface and prevents the hydrolysis of HSQ during photoresist stripping. Dielectric degradation can be prevented by NH3 plasma treatment.
Effects of oxygen plasma ashing on barrier dielectric SiCN film
(2005)
Chen, CW
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Chang, TC
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Liu, PT
;
Tsai, TM
;
Tseng, TY
Effects of oxygen plasma ashing on barrier dielectric SiCN films have been studied for various ashing conditions. According to X-ray photoelectron spectra analyses, Si-O-2 bonds appear at the surface of SiCN film after O-2 plasma ashing. The formation of the oxidized layer, SiOxCN, at the surface of the SiCN film effectively reduces the leakage current as a consequence. The leakage conduction of the SiCN films has been investigated to be Schottky emission at the fields between 0.4 and 1.2 MV/cm. Also, the increase of Schottky barrier height between SiCN and the metal is calculated to be 42 meV after O-2 plasma ashing. (C) 2004 The Electrochemical Society.
Electrical degradation of N-channel poly-Si TFT under AC stress
(2005)
Chen, CW
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Chang, TC
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Liu, PT
;
Lu, HY
;
Tsai, TM
The degradation of n-channel poly-silicon thin film transistor (poly-Si TFT) has been investigated under dynamic voltage stress. The ON-current of TFT is 0.03 times the initial value after 1000 s stress. However, both the sub-threshold swing and threshold voltage almost kept well during the ac stress. The current crowding effect was rapidly increased with the increasing of stress duration. The creation of effective trap density in tail-states of poly-Si film is responsible for the electrical degradation of poly-Si TFT. Moreover, the damaged regions were evidenced to be mainly near the source/drain regions according to the electrical analyses. (c) 2005 The Electrochemical Society. All rights reserved.
Eliminating dielectric degradation of low-k organosilicate glass by trimethylchlorosilane treatment
(2002-07-01)
Chang, TC
;
Liu, PT
;
Mor, YS
;
Tsai, TM
;
Chen, CW
The interaction between low-k organosilicate glass (OSG) and photoresist removal is investigated. O-2 plasma ashing and chemical wet stripper are commonly performed to remove photoresist (PR) in integrated circuit fabrication. However, O-2 plasma or wet stripper will attack function groups and cause Si-OH group formation in OSG film during PR removal processing. The Si-OH groups often lead to moisture uptake and consequently dielectric degradation will occur in OSG film. Trimethylchlorosilane (TMCS) treatment can negate the damage in the OSG film after the PR removal process. In addition, chemical TMCS can react with Si-OH groups and reduces moisture uptake so that the dielectric characteristic of OSG can be maintained. Hence, TMCS treatment is a promising method for photoresist removal. (C) 2002 American Vacuum Society.
Elimination of dielectric degradation for chemical-mechanical planarization of low-k hydrogen silisesquioxane
(2001-05-01)
Chang, TC
;
Liu, PT
;
Tsai, TM
;
Yeh, FS
;
Tseng, TY
The characteristics of post-chemical mechanical polishing (post-CMP) low-k hydrogen silsesquioxane (HSQ) have been investigated in this work. Dielectric properties of HSQ are damaged by the CMP process. We propose NH3-plasma treatment to improve the characteristics of post-CMP HSQ film. Both of the leakage current and dielectric constant of NH3 plasma-treated HSQ are significantly decreased as compared with those of untreated HSQ. NH3 plasma treatment slightly nitridates the surfaces of the polished HSQ film. The thin nitride layer prevents moisture absorption in the post-CMP HSQ. As a result, the dielectric degradation of HSQ after the CMP process can be effectively recovered using the NH3 plasma treatment.
Enhancing the resistance of low-k hydrogen silsesquioxane (HSQ) to wet stripper damage
(2001-11-01)
Chang, TC
;
Mor, YS
;
Liu, PT
;
Tsai, TM
;
Chen, CW
The interaction between low-k hydrogen silsesquioxane (HSQ) film and wet stripper was investigated. The wet stripper has been commonly used to remove photoresister in IC integration processing. However, the high content of alkalinity in the stripper solution often leads to the hydrolysis of HSQ film, forming dangling bonds in the HSQ. The dangling bonds in the HSQ film can easily react with hydroxide ion (OH-) in wet stripper solution and form Si-OH bonds. The resultant HSQ film will tend to uptake water and consequently increase both the leakage current and dielectric constant. In this study, H-plasma pre-treatment was applied to the HSQ film. The hydrogen plasma treatment passivates the HSQ surface and prevent HSQ from water uptake during photoresist stripping. Therefore, dielectric degradation can be avoided with the H-2-plasma pre-treatment. (C) 2001 Elsevier Science B.V. All rights reserved.
Improvement of low dielectric constant methylsilsesquioxane by boron implantation treatment
(2001-11-01)
Chang, TC
;
Mor, YS
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Liu, PT
;
Tsai, TM
;
Chen, CW
The organic silsesquioxane, methylsilsesquioxane (MSQ), exhibits a low dielectric constant because of its lower film density compared with thermal oxide. In this study, boron implantation treatment is investigated in order to improve the quality of MSQ. The small size of boron atoms do not damage the chemical bonding of the MSQ film. In addition, the formation of densified surfaces after boron implantation can reduce the probability of moisture uptake into the MSQ. Therefore, the leakage current of MSQ film is significantly decreased and the low-k properties of MSQ film can be maintained. (C) 2001 Elsevier Science B.V. All rights reserved.
Investigation of the electrical properties and reliability of amorphous SiCN
(2004-01-30)
Chen, CW
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Chang, TC
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Liu, PT
;
Tsai, TM
;
Huang, HC
Amorphous SiCN (a-SiCN) is a candidate for barrier dielectric and has lower dielectric constant (ksimilar to5) relative to the commonly used barrier SiN (ksimilar to7). In this study, we investigate the leaky behavior and barrier characteristics of a-SiCN (k: 4similar to5) doped with different nitrogen concentration. The leaky behavior of a-SiCN is Poole-Frenkel at high electric field. This is similar to SiN. Thermal stability of a-SiCN films is good enough to meet the prescription in back-end-of-line fabrication process. The bias-temperature stress (BTS) test has been conducted on a-SiCN to investigate the barrier ability against copper 15/16penetration. We find that a-SiCN could sustain the stress of electric field up to 4 mV/cm at 150 degreesC. In addition, a-SiCN films with higher nitrogen concentration exhibit better barrier property against copper penetration. The SIMS spectra also have been used to monitor the distributions of copper after different BTS conditions, confirming our inference on leakage mechanism. (C) 2003 Elsevier Science B.V. All rights reserved.
Leakage conduction behavior in electron-beam-cured nanoporous silicate films
(2005-05-02)
Liu, PT
;
Tsai, TM
;
Chang, TC
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電子工程學系及電子研究所
;
光電工程學系
This letter explores the application of electron-beam curing on nanoporous silicate films. The electrical conduction mechanism for the nanoporous silicate film cured by electron-beam radiation has been studied with metal-insulator-semiconductor capacitors. Electrical analyses over a varying temperature range from room temperature to 150 degrees C provide evidence for space-charge-limited conduction in the electron-beam-cured thin film, while Schottky-emission-type leaky behavior is seen in the counterpart typically cured by a thermal furnace. A physical model consistent with electrical analyses is also proposed to deduce the origin of conduction behavior in the nanoporous silicate thin film. (c) 2005 American Institute of Physics.
Method to improve chemical-mechanical-planarization polishing rate of low-k methyl-silsesquiazane for ultralarge scale integrated interconnect application
(2004-05-01)
Chang, TC
;
Tsai, TM
;
Liu, PT
;
Yan, ST
;
Chang, YC
In this work, characteristics of low-k methyl-silsesquiazane (MSZ) for the chemical-mechanical-planarization (CMP) process using oxygen plasma pretreatment were investigated in detail. The low-dielectric-constant (low-k) MSZ was prepared by a spin-on deposition process. The resultant wafers were followed by an oxygen (O-2) plasma treatment. After oxygen plasma treatment, the CMP process was implemented. Electrical and material analyses were utilized to explore the characteristics of post-CMP MSZ. Experimental results showed that the polish rate. of MSZ film with O-2 plasma pretreatment was increased as much as two times in magnitude, as compared to that of the MSZ without O-2 plasma pretreatment. In addition, the post-CMP MSZ exhibited superior electrical properties. These results clearly indicated that the modification surfaces that resulted from O-2-plasma treatment facilitated CMP MSZ. After CMP polishing, the MSZ film still maintained low-k quality. (C) 2004 American Vacuum Society.
Moisture-induced material instability of porous organosilicate glass
(2003-04-01)
Chang, TC
;
Chen, CW
;
Liu, PT
;
Mor, YS
;
Tsai, HM
The mechanism of leakage current of porous organosilicate glass (POSG) with O-2 plasma ashing is investigated. The O-2 plasma ashing often deteriorates the POSG film, causing moisture uptake. We find that the leakage-current mechanism of POSG transforms from Schottky emission into ionic conduction after O-2 plasma treatment. The mobile ions (H+,OH-) supported by absorbing moisture move easily when an external electric field is applied to POSG film, which leads to the ionic conduction leakage current across the moisture-absorbing POSG film. Hence, the leakage current density is drastically increased about four to five orders of magnitude compared with untreated POSG film. (C) 2003 The Electrochemical Society.
Preventing dielectric damage of low-k organic siloxane by passivation treatment
(2002-04-01)
Chang, TC
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Mor, YS
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Liu, PT
;
Tsai, TM
;
Chen, CW
An organic SOG, the Hybird-Organic-Siloxane-Polymer (HOSP), has high applicability to ULSI processes, because of the low dielectric constant of about 2.5. However, the HOSP film will be damaged after photoresist removal. The function groups of HOSP will be destroyed by O-2 plasma ashing and chemical wet stripper, which leads to electrical degradation. In order to avoid the issue, H-2 plasma treatment is proposed to prevent HOSP film from photoresisit stripping damage. It is found that leakage current is decreased significantly and the dielectric constant is still maintained at a low k value even after photoresist stripping. Therefore, H-2 plasma treatment is an effective technique to enhance the resistance of HOSP film against photoresist stripping damage. (C) 2002 Elsevier Science B.V. All rights reserved.