Cheonman Shim

Significant improvement of electrical and thermal properties of low dielectric constant plasma polymerized paraxylene thin films by postdeposition H2+He plasma treatment

Electrical and thermal properties of plasma polymerized paraxylene (PPpX) thin films were significantly improved by postdeposition H2+He plasma treatment. Plasma treatment decreased dielectric constants and increased thermal stability. As the plasma treatment time increased from 0 to 6 min, the relative dielectric constant k decreased from 3.23 to 2.77. Suppression of C=O and O–H group formation and increase of C–H groups in the PPpX film were thought to contribute to the reduction of the k values. Plasma treatment enhanced the thermal stability of PPpX thin films. While the untreated PPpX thin film was stable only to 400 °C, plasma-treated films were stable up to 450 °C. H2+He plasma treatment did not increase the leakage current through the PPpX films notably and did not degrade the surface smoothness, either.

Plasma enhanced CVD of low dielectric constant plasma polymerized decahydronaphthalene thin films

Properties of low dielectric constant, plasma polymerized decahydronaphthalene (PPDHN) thin films deposited by plasma enhanced (PE) CVD were investigated. Plasma power significantly affected the dielectric constants and thermal stability of the deposited films. As plasma power was increased from 30 W to 90 W, the relative dielectric constant, k, of the deposited PPDHN thin films increased from 2.65 to 3.12. With the increase in plasma power, integrated peak areas of C=O stretching (-1700 cm -1 ) and O-H stretching (-3400 cm -1 ) vibrations increased, while that of the CH x stretching (-2900 cm -1 ) vibration decreased. All the PPDHN films were thermally stable to 350°C. Upon annealing at 400°C, the film deposited at 30 W showed -35 % thickness reduction, while the film deposited at 90 W showed only -15 % thickness reduction. All the deposited thin films showed a leakage current density below 10 -8 A cm -2 at 1 MVcm -1 .

Characteristics under bias-temperature-stress of Cu/low-k a-SiCO:H structures prepared by plasma enhanced chemical vapor deposition using a hexamethyldisilane precursor and Cu sputtering

Interactions of Cu films deposited on low dielectric constant (low-k) a-SiCO:H films under bias-temperature-stress (BTS) were investigated. The low-ka-SiCO:H film with a relative dielectric constant k of 2.75 was deposited by plasma enhanced chemical vapor deposition (PECVD) using hexamethyldisilane (HMDS) as a precursor. From the BTS data, it was evaluated that the low-ka-SiCO:H film can be remaining insulating, when put adjacent to Cu, for 105 h at 180°C under 1 MV/cm. The reason of very slow Cu diffusion into our low-ka-SiCO:H film under BTS can be speculated due to a high amount of carbon species and low amounts of SiOx species and polar groups in the film.

Effects of Post-Deposition Heat Treatment on the Properties of Low Dielectric Constant Plasma Polymerized Decahydronaphthalene Thin Films Deposited by Plasma-Enhanced Chemical Vapor Deposition

Effects of post-deposition heat treatment on the properties of plasma polymerized decahydronaphthalene (PPDHN) thin films were studied. Heat treatment at 150°C and 250°C decreased the relative dielectric constant k from 2.80, the k value of the as-deposited film, to 2.52 and 2.63, respectively. With the increase of the temperature of heat treatment, the thermal stability of the PPDHN thin film improved. Changes of the k value and thermal stability were related to changes of C-H, C=O and O-H group density.

Characteristics of Copper Diffusion into Low Dielectric Constant Plasma Polymerized Cyclohexane Thin Films

Copper (Cu) diffusion into low dielectric constant plasma polymerized cyclohexane (PPCHex) thin films deposited by plasma enhanced chemical vapor deposition upon annealing was investigated. Cu diffusion was analyzed by current–voltage (I–V) measurement, Rutherford backscattering spectroscopy (RBS), and transmission electron microscopy (TEM). From I–V measurement and TEM analysis, it was revealed that PPCHex thin films were resistant to Cu diffusion up to 400°C, while there was a notable amount of Cu diffused into the PPCHex thin films after 450°C annealing. RBS was not sensitive enough to detect a small amount of Cu diffused into the PPCHex films. Improved Cu diffusion resistance of our PPCHex thin films compared to thin films of chemically synthesized polymers is thought to be due to high cross-linking among film-forming species of plasma polymers.

Relationship between C=C bonds and mechanical properties of carbon rich low-k films deposited by plasma enhanced chemical vapor deposition

We have studied the relationship between C=C bonds and the mechanical properties of different low-k films deposited by plasma enhanced chemical vapor deposition (PECVD) using a p-xylene and/or hexamethyldisilane (HMDS) precursor. The three types of films were called plasma polymerized p-xylene (PPpX) using p-xylene only, plasma polymerized p-xylene:hexamethyldisilane (PPpX:HMDS) using a mixture of p-xylene and HMDS, and plasma polymerized hexamethyldisilane (PPHMDS) using HMDS only as precursors. The mechanical strengths such as Youngs modulus and hardness decreased as a function of annealing temperature, while C=C bonds increased in number. We suggest that the mechanical properties of low-k films containing a large amount of C and small amounts of Si and/or O are closely related to the generation of C=C bonds in the films after annealing, and not to the decrease in the film density. This was investigated by Fourier transform Raman (FT-Raman) spectroscopy.

Effects of annealing on the properties of Cu/low k polymer/Si structures prepared by plasma polymerization of decahydronaphthalene and tetraethylorthosilicate and Cu sputtering

Abstract Effects of annealing on the properties of a structure made of copper (Cu) and low dielectric constant (low- k ) plasma polymer films were investigated. Low- k plasma polymer films used in the experiment were deposited using a mixture of decahydronaphthalene (C 10 H 18 : DHN) and tetraethylorthosilicate (Si–(O–C 2 H 5 ) 4 : TEOS) as the precursors and were referred to as PPDHN:TEOS films. In current–voltage measurements of Cu/PPDHN:TEOS/Si/Al structures for which Cu/PPDHN:TEOS/Si were annealed before the Al back-contact deposition, 400 and 450 °C annealed samples showed lower leakage current than the not-annealed sample possibly due to improvement of the Cu/PPDHN:TEOS interface. 500 and 580 °C annealed samples showed slightly and significantly higher leakage currents, respectively, than 400 and 450 °C annealed samples. Secondary ion mass spectroscopy analysis of Cu/PPDHN:TEOS structures and Fourier transform infrared absorption spectroscopy analysis of the PPDHN:TEOS films suggested that the increase of leakage current of Cu/PPDHN:TEOS/Si/Al structures after 500 and 580 °C annealing is caused by the compositional and structural change of the PPDHN:TEOS films, rather than by the diffusion of Cu into the PPDHN:TEOS films

Copper Hillock Induced Copper Diffusion and Corrosion Behavior in a Dual Damascene Process

A copper hillock induced interconnect failure mechanism is presented. The copper hillock is frequently generated during a copper dual damascene process and hillock formation is found to degrade the interconnect integrity by affecting the following process steps. The copper hillock appears to damage the SiN capping layer and results in copper corrosion during via etch. The corrosion generates copper particles inside via holes and the defects are found to make the following metal depositions incomplete during via formation. Based on the observations, a copper hillock induced defect model is proposed and a new copper process is suggested to reduce copper hillocks.

Effects of Postdeposition in situ Heat Treatment on the Properties of Low Dielectric Constant Plasma Polymer Films Deposited Using Decahydronaphthalene and Tetraethyl Orthosilicate as the Precursors

We investigated effects of postdeposition heat treatment (HT) on the properties of plasma polymer films deposited by plasma-enhanced chemical vapor deposition using a mixture of decahydronaphthalene and tetraethyl orthosilicate as the precursors, which were referred to as plasma-polymerized decahydronaphthalene:tetraethyl orthosilicate (PPDHN:TEOS) films. HTs at 350, 450, and 500 °C decreased the relative dielectric constant k of the PPDHN:TEOS films from 3.16, the k value of the as-deposited film, to 2.82, 2.72, and 3.02, respectively. The change of k value as a function of HT temperature was correlated with the change of Fourier transform infrared absorption peaks of O-H, C = O, and Si-related groups. As the HT temperature increased, the thermal stability of the PPDHN:TEOS film increased. PPDHN:TEOS films, as-deposited or heat treated, showed leakage current density in the order of 10 - 7 A/cm 2 at 1 MV/cm.

Selectively Formed Metal Organic Chemical Vapor Deposition TiSiN and Ta Barrier Metal Using Direct Contact Via Process for Sub-65 nm Interconnects

We report integration of metal organic chemical vapor deposition (MOCVD) TiSiN barrier metal into 65 nm low-k dielectric (k=2.9) interconnects. Selective TiSiN barrier was formed along via trench wall using direct contact via (DCV) process and subsequent Ta incorporation into Cu was found to significantly improve electromigration (EM) reliability. Also, a large reduction of 0.1 µm via/line resistances is achieved. The proposed integration method allows MOCVD TiSiN usable as a barrier metal for the nano scale interconnects, taking advantages of high throughput and excellent step coverage of MOCVD process compared to other barrier processes.