Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
שיקוע מפאזה גזית - יישומים • יישומי מבודדים ומוליכים ליצירת חיבורי ביניים פרופ ’יוסי שחם המחלקה לאלקטרוניקה פיזיקלית ,אונ ’ ת”א. מבודדים • • • • תחמוצת סיליקון סיליקון ניטריד פולימרים אורגנים מבודדים עם מקדם דיאלקטרי נמוך)( LOW-K תחמוצת סיליקון Crystalline forms: quartz, cristobalite, tridymite Amorphous: silica (brand name, can be mixed) Methods of preparation: Deposition Thermal oxidation מבנה תחמוצת סיליקון The oxygen atoms are electronegative, and some of the silicon valence electron density is transferred to the oxygen neighbors, מבנה מולקולת תחמוצת סיליקון The Si-O distance is 1.61 A (0.16 nm) which is slightly smaller than the sum of the covalent "radii" of the atoms: Si (0.11 nm) + O(0.066 nm) = 0.18 nm תחמוצת סיליקון היא אמורפית • The result of this flexibility in the bridge bonds is that SiO2 can easily form amorphous materials • amorphous silicon dioxide will not crystallize upon annealing at normal temperatures. (process known as "Devitrification" ) מבנה תחמוצת סיליקון The amorphous structure is tends to be very "open": even in thermally-grown oxides, channels exist through which small positive ions such as Na+ and K+ can readily migrate. These ions can move under the influence of electric fields within the gate oxides of MOS transistors, causing shifts in the voltage at which the transistor turns on ("threshold shifts"). Exclusion of such ions is imperative for reliable operation of MOS transistors and integrated circuits. תחמוצת סיליקון r, density = 2.0-2.3 gm/cm3 s= varies widely EBV >1E7 V/cm in thermal oxides; Thermal conductivity = 0.01 W/cm K (bulk) Thermal diffusivity = 0.009 cm2/sec (bulk) CTE = 0.5 ppm/ K n= 1.46 [thermal oxide] er = 3.9 [thermal oxide]; note: properties of CVD oxides vary widely depending on H עם מים ראקציות • The first reaction has little change in enthalpy and is nearly reversible; locally strained bonds, with reduced bond energy, are particularly vulnerable to attack by water ("hydrolysis"). Oxides containing large amounts of SiOH are more hygroscopic, and readily adsorb water molecules from the air. • The water can migrate through the deposited materials to the gate oxide, there causing drifts in performance of transistors under bias, impairing hot electron reliability, also known as gate oxide integrity or GOI. The water molecules can, however, be consumed by the reactions with Si-H groups: this is the basis of the use of silicon-rich oxides as water getters or barriers. תחמוצות סיליקון עם סימום • Phosphosilicate glass (PSG) flows readily at 1000 C for 6-8 weight% P • Borophosphosilicate glass (BPSG) can achieve a lower flow temperature: typically around 900 C for 4-5 wt.% of each dopant. (notethat 4 weight % of boron is a very large mole percentage -- around 12 at.% depending on composition-- because B atoms are so light.) שיטות לשיקוע מבודדים Precursors SiH4, O2; PH3 and B2H6 as dopants; 400-500 C TEOS, O2; TMP and TMB as dopants SiH4, N2O TEOS, O3; TMP and TMB as dopants Technique Showerhead APCVD Tube LPCVD Injector APCVD Tube LPCVD ("HTO"); Applications obsolete BPSG BPSG, PSG final passivation spacer oxides, gate oxide sandwich, isolation sandwich; PECVD; 300 - 350 C BPSG ILDs cap layers for BPSG or PSG; final passivation PECVD, 200-450 C cap layers and barrier layers for spin-on glass; final passivation Showerhead "SACVD", IMD sandwich; BPSG; final 200-700 Torr, 350-500 passivation; spacer oxide C, or injector APCVD, 350-500 C SiO2 CVD from Silane +oxygen SiO2 CVD from Silane +oxygen SiO2 CVD from Silane +oxygen (3) תלות קצב השיקוע Magnetic enhancement TEOS-Tetra Ethyle Ortho SIlicate TEOS CVD שיקוע תחמוצת על משטח בעזרת TEOS TEOS - CVD (3) TEOS +OZONE CVD הוספת אוזון מעלה את קצב השיקוע ריאקצית השיקוע המאמץ בשיכבה מולקולת אמוניה שיקוע טיטנים ניטריד מפאזה גזית TiN + byproducts שיקוע טיטנים ניטריד מפאזה גזית TiN + byproducts Diffusion barrier comparison, (M. Mossavi et al., IITC 98) Properties Ta - IMP TaN - IMP TiN - CVD Resistivity 170 .cm 250 .cm 130 .cm Stress +350 MPa +1500 MPa -750 MPa Barrier performance 6x1016 at/cm3 6x1017 at/cm3 1017 at/cm3 40%/40% 100%/100% 20 1 Sidewall/bottom 20%/40% coverage (0.3m) CMP selectivity 23 vs. Cu MOCVD TiN Precursors: Tetrakis-dimethylamino Titanium Ternary phase diagrams •The lack of Ta-Cu compounds yield a broad range of compositions in equilibrium with Cu. •Ti-rich compositions are expected to react with Cu N N TiN TaN Ti2N Ta2N Cu Ta Cu Cu Ti Cu Ti 4 4 3 CuTi CuTi2 Ti שיקוע מגעW שיקוע שער עם Wסיליסייד שיקוע סלקטיבי בתוך מגע -שלבI שיקוע סלקטיבי בתוך מגע -שלבII אמינות של מגעW אמינות של מגע W -היווצרות VOID High K materials (I) קבל אגירת מטען ל- DRAM חומרים לקבלי אגירה סיכום יישומי CVDכיום טונגסטן טיטניום ניטריד ,טנטלום ניטריד נחושת? מבודדים -תחמוצת סיליקון ו- LOW-K