Transcript ללא כותרת שקופית - Tel Aviv University

‫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
(0.3m)
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