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.

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.

Direct Patterning of Low-k Hydrogen Silsesquioxane Using X-Ray Exposure Technology †Electrochemical and Solid-State Letters, 6, G69 „2003...‡ T. C. Chang, T. M. Tsai, P. T. Liu, Y. S. Mor, C. W. Chen, J. T. Sheu, and T. Y. Tseng Department of Physics, National Sun Yat-Sen University, Kaohsiung, Taiwan Institute of Electronics, National Chiao Tung University, Hsin-Chu, Taiwan National Nano Device Laboratory, Hsin-Chu 300, Taiwan Department of Electrical Engineering, National Chi Nan University, Puli-Nantou, Taiwan 545

The interaction between low dielectric constant (low-k) hybrid organic siloxane polymer (HOSP) and O-2 plasma ashing has been investigated. O-2 plasma ashing is commonly performed to remove the photoresist (PR) during integrated circuit fabrication. However, dielectric loss usually occurs in the HOSP films during the PR removal process. In order to eliminate dielectric loss originating from an O-2 plasma attack, hexamethyldisilazane (HMDS) treatment is proposed to repair the damage in the HOSP film. HMDS can react with Si-OH bonds and reduce moisture uptake. Moreover, the leakage current and the dielectric constant is decreased significantly when damaged HOSP film undergoes HMDS treatment. For this reason, HMDS treatment is a promising method to apply to the photoresist removal. (C) 2002 The Electrochemical Society.

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.

The dielectric properties of organic-porous silica films deteriorate after photoresist removal processing. O-2 plasma ashing has been commonly used to remove photoresist. Nevertheless, the O-2 plasma will destroy the functional groups and induce moisture uptake in porous silica films. In this study, trimethylchlorosilane (TMCS) is used to repair the damage to porous silica caused by the O-2 plasma ashing process. The leakage current and dielectric constant will decrease significantly after the TMCS treatment is applied to damaged porous silica. These experimental results show that the TMCS treatment is a promising technique to repair the damage to porous silica during photoresist removal processing. (C) 2002 The Electrochemical Society.

An organic low dielectric constant (low-k) material, hybrid-organic-siloxane-polymer (HOSP), is integrated into multilevel interconnection using X-ray exposure technology. In conventional IC integration processes, photoresist (PR) stripping with O2 plasma and wet chemical stripper is an inevitable step. However, dielectric degradation often occurs when low-k dielectrics undergo the PR stripping process. This limits the application of incorporating low-k material into semiconductor fabrication. In order to overcome the integration issue, a novel pattern method, X-ray direct patterning is proposed. In this technology, the dielectric regions illuminated by X-ray will be cross-linked, forming the desired patterns. At the same time, the regions without X-ray illumination are dissolvable in a solvent of HOSP film. Direct-patterning processes have several advantages: (1) they do not need PR to define patterns; thereby the damage from PR stripping can be eliminated, (2) the complex etching on low-k dielectrics can be eliminated, (3) the process steps are simplified. In this work, we will investigate the dielectric properties of HOSP film with X-ray curing for the first time. Additionally, a scanning electron microscope image of circle pattern was made to verify the process practicability.

The interaction between low-k organosilicate glass (OSG) and photoresist removal is investigated. O2 plasma ashing and chemical wet stripper are commonly performed to remove photoresist (PR) in integrated circuit fabrication. However, O2 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.

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 O2 plasma ashing and chemical wet stripper, which leads to electrical degradation. In order to avoid the issue, H2 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, H2 plasma treatment is an effective technique to enhance the resistance of HOSP film against photoresist stripping damage.

O 2 plasma ashing is commonly used to remove photoresist. The effect of O2 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 O2 plasma-damaged POSG undergoes HMDS treatment at 80 °C for 15 min. Therefore, HMDS treatment is the effective technique to repair the electrical degradation to POSG film during photoresist stripping processing.

The integration process, low-k hybrid-organic-siloxane-polymers (HOSP) and photoresist stripping process have been investigated. The dielectric properties of HOSP films are degradated after photoresist removal. This is because photoresist stripping processes destroy the functional groups and induce moisture uptake in HOSP films. In this study, NH3-plasma treatment was used for HOSP films to form a thin nitrogen-containing layer, preventing HOSP films from O2 plasma ashing and chemical wet stripper damage during photoresist removal. The leakage current is decreased significantly and the dielectric constant is maintained at a low value after photoresist removal. These experimental results show that NH3 treatment is a promising technique to enhance the resistance of HOSP films to the photoresist stripping process.

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.

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, H2-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 H2-plasma pre-treatment.

The organic low-k hybrid-organic-siloxane-polymer (HOSP(R)) has been investigated as an intermetal dielectric. The presence of Si-H and Si-CH3 bonds instead of partial Si-O bonds lowers the dielectric constant compared to conventional siloxane-based spin-on glass. However, dielectric degradation occurs due to the destruction of functional groups in HOSP during the photoresist ashing process. In this work, we have applied NH3 plasma nitridation to improve the quality of HOSP films. The NH3 plasma process converts the organic HOSP surface into an inorganic surface by formation of a thin inert SiNx passivation layer. The inert layer can enhance the resistance of the HOSP film to moisture uptake and O-2 plasma attack during photoresist stripping. In addition, it effectively prevents copper from penetrating the HOSP film. (C) 2001 The Electrochemical Society. All rights reserved.

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.

This work has investigated the electrical and material characteristics of post-chemical mechanical planarization (CMP) methylsilsesquioxane (MSQ). Experimental results have shown that the dielectric properties of low k MSQ deteriorate after the CMP process. However, by applying H-2-plasma post-treatment, the degraded characteristics can be restored to a similar state as that of a pre-CMP MSQ film. Material and electrical analyses were performed to elucidate the detailed mechanisms of H-2-plasma treatment on post-CMP MSQ. H-2-plasma treatment provides active hydro en radicals to passivate the dangling bonds exposed in the MSQ after the CMP process. The hydrogen-rich passivation layer is hydrophobic and effectively prevents further moisture uptake. Therefore, a degradation-free CMP process can be achieved employing H-2-plasma treatment. (C) 2000 The Electrochemical Society. S0013-4651(00)04-098-2. All rights reserved.

The organic silsesquioxane, methylsilsesquioxane (MSQ), has a low dielectric constant because of its low film density compared to thermal oxide. However, the quality of the MSQ film is degraded by the damage caused by oxygen plasma and hygroscopic behavior during photoresist stripping. In this work, we have studied the ability of H2 plasma treatment to improve the quality of MSQ. The leakage current of MSQ decreases as the H2 plasma treatment time is increased. The dielectric constant of treated samples remains constant (∼2.7). In addition, the thermal stability of MSQ film is significantly promoted. The H2 plasma treatment can provide additional hydrogen to passivate the inner structure of porous MSQ film, and reduce the probability of moisture uptake. Therefore, H2 plasma treatment can improve the quality of low-k MSQ film and reduce the issue of photoresist stripping in the integrated process.

The new solutions, hydroxylamine sulfate [(NH2OH)2H2SO4] combined with CuSO4, for cleaning Al via were investigated. It is found that the cleaning capability of hydroxylamine sulfate combined with CuSO4 is better than that of hydroxylamine sulfate. Low via resistance of electrical test structure is obtained if the via is cleaned by this new cleaning solution. The hydroxylamine sulfate can efficiently remove Al3O2 and leave the clean Al on the surface of via. Then, the Cu ion in this new solution will immediately react with clean Al and form a copper passivating layer on the surface of via. The copper is more stable than aluminum in the environment and hard to be oxidized. Therefore, hydroxylamine sulfate combined with CuSO4 can provide excellent cleaning capability for aluminum via holes. Also, the clean surface on the bottom of via is helpful for tungsten nucleation in via during CVD-W deposition. Therefore, a low via resistance and good selectivity of tungsten plug are obtained when the Al via is precleaned with this new solution.

The quality of organic low-k methylsilsesquioxane (MSQ) film is degraded by the damage of oxygen plasma and hygroscopic behavior during photoresist stripping. In addition, the interaction between MSQ and copper is worth investigating. In this work, we have studied the H2 plasma treatment to improve the quality and enhance the copper penetration resistance of MSQ. Experimental results show the leakage current of MSQ decreases as the H2 plasma treatment time is increased. The dielectric constant of treated samples also remains constant (∼2.7). In addition, the copper diffusion resistance of MSQ film is significantly promoted. The H2 plasma treatment can provide additional hydrogen to passivate the inner structure of porous MSQ film as well as reduce the probability of moisture uptake and interaction with Cu atoms. Therefore, the low-k dielectric properties of MSQ are significantly enhanced by H2 plasma treatment.

The organic silsesquioxane, methylsilsesquioxane (MSQ), has a low dielectric constant because of its lower film density compared to thermal oxide. However. the quality of MSQ film is degraded by the damage of oxygen plasma and hygroscopic behavior during photoresist stripping. In this work, we studied the N2O plasma treatment for improving the quality of MSQ. The leakage current of MSQ decreases as the N2O plasma treatment time is increased. The dielectric constant of N2O plasma-treated sample remains constant (similar to 2.7). In addition, the thermal stability of MSQ film can be enhanced. The role of N2O plasma is to convert the surface layer of organic MSQ into inorganic type by decomposition of the alkyl group and thus form a passivation layer. The inert passivation layer enhances the resistance to moisture uptake and O-2 plasma attack. Therefore, N2O plasma-treatment greatly improves the quality of low k MSQ film and removes the issue of photoresist stripping in the integrated process. (C) 1999 The Electrochemical Society. S0013-4651(98)10-071-X. All rights reserved.