Process for the generation of metal-containing films

Abstract

Described herein is a process for preparing inorganic metal-containing films including bringing a solid substrate in contact with a compound of general formula (I) or (II) in the gaseous state ##STR00001## where A is NR.sub.2 or OR with R being an alkyl group, an alkenyl group, an aryl group, or a silyl group, E is NR or O, n is 1, 2 or 3, and R′ is hydrogen, an alkyl group, an alkenyl group, an aryl group, or a silyl group, wherein if n is 2 and E is NR or A is OR, at least one R in NR or OR bears no hydrogen atom in the 1-position.

Claims

1. A process for preparing inorganic metal-containing films comprising bringing a solid substrate in contact with a compound of general formula (I) or (II) in the gaseous state ##STR00035## wherein A is NR.sub.2 or OR with R being an alkyl group, an alkenyl group, an aryl group, or a silyl group, E is NR or 0, n is 1, 2 or 3, and R′ is hydrogen, an alkyl group, an alkenyl group, an aryl group, or a silyl group, wherein if n is 2 and E is NR or A is OR, at least one R in NR or OR bears no hydrogen atom in the 1-position, wherein a metal-containing compound is deposited from the gaseous state onto the solid substrate before bringing it in contact with a compound of general formula (I) or (II).

2. The process according to claim 1, wherein R is methyl, ethyl, tert-butyl, trimethylsilyl, or the two R in A when A is NR.sub.2 form together a five membered ring, and R′ is hydrogen.

3. The process according to claim 1, wherein the metal-containing compound contains Ti, Ta, Mn, Mo, W, Al, Co, Ga, Ge, Sb, or Te.

4. The process according to claim 1, wherein the metal-containing compound is a metal halide.

5. The process according to claim 1, wherein the process optionally further comprises decomposing the compound of general formula (I) or (II) that adsorbs to a surface of the solid substrate, and wherein the process is performed at least twice.

6. The process according to claim 1, wherein the compound of general formula (I) has a molecular weight of not more than 600 g/mol.

7. The process according to claim 1, wherein the compound of general formula (I) has a vapor pressure at least 1 mbar at a temperature of 200° C.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1 shows the thermogravimetric analyses (TGA) of compound (Ie-1), (Ie-5) and (III-1).

(2) FIG. 2 shows the X-ray crystal structure of compound (Ie-5).

(3) FIG. 3 top left demonstrates the growth rate and bulk resistivity versus pulse length of compound (Ie-1). FIG. 3 top right demonstrates the growth rate and resistivity versus pulse length of TiCl.sub.4. FIG. 3 lower left demonstrates the growth rate and resistivity versus temperature. FIG. 3 lower right demonstrates the film thickness versus number of cycles.

(4) FIG. 4 shows the GI-XRD patterns of TiC.sub.xN.sub.y films deposited at 280° C. (bottom) and 400° C. (top).

(5) FIG. 5 demonstrates the growth rate and film resistivity versus temperature for films deposited from WCl.sub.6 and compound (Ie-1) after 250 ALD cycles.

(6) FIG. 6 shows the cross-sectional SEM image of a 42 nm Al film deposited on a Cu substrate at 120° C. after 125 ALD cycles of AlCl.sub.3 and compound (Ie-1).

(7) FIG. 7 demonstrates the GI-XRD pattern of a 400 nm thick Al film deposited on a thermal oxide (100 nm on Si) at 120° C. after 1000 ALD cycles.

EXAMPLES

Example 1a

Synthesis of the Ligand of Compound (Ie-1)

(8) ##STR00029##

(9) A 250 mL round-bottomed flask was charged with 2-chloro-N,N-dimethylethylamine hydrochloride (25.0 g, 0.175 mol), tert-butylamine (115 mL, 1.1 mol, 6. 3 equiv.), water (5 mL), and heated to gentle reflux at 70° C. for 18 h. After cooling to ambient temperature, hexanes and water (40 mL each) were added and transferred to a separatory funnel. The aqueous fraction was washed with hexanes (3×20 mL) and the combined hexanes fractions were washed with brine, dried over MgSO.sub.4, and evaporated under reduced pressure to yield a clear, colorless oil. (10.898 g, 43%) The analytically pure product was used routinely without further purification, but it can be purified by vacuum distillation at 65° C., 18 Torr.

(10) .sup.1H NMR (400 MHz, C.sub.6D.sub.6) δ=2.56 (t, 2H), 2.34 (t, 2H), 2.06 (s, 6H), 1.29 (bs, 1H), 1.06 (s, 9H) .sup.13C NMR (100 MHz, C6D.sub.6) δ=60.52, 50.00, 45.74, 40.53, 29.61

Example 1b

Synthesis of Compound (Ie-1)

(11) ##STR00030##

(12) A 250 mL Schlenk flask was charged with LiAlH.sub.4 (0.854 g, 22.5 mmol), diethyl ether (70 mL), and cooled to 0° C. on an ice bath. A separate 100 mL Schlenk flask was charged with AlCl.sub.3 (1.000 g, 7.5 mmol) and diethyl ether (50 mL). The AlCl.sub.3 solution was cannulated into the LiAlH.sub.4 solution and the resulting cloudy solution stirred at ambient temperature for 30 min. The mixture was cooled to −30° C. and a solution of 1-tert-butylamino-2-dimethylaminoethane (3.934 g, 27.3 mmol) in diethyl ether (25 mL) was added. The resulting mixture stirred at ambient temperature over 4 h and was then filtered through Celite and evaporated under reduced pressure. When most of the diethyl ether had been evaporated, the flask was cooled on an ice bath to solidify the low-melting product (3.345 g, 71%). M.P.: 31-32° C.

(13) .sup.1H NMR (600 MHz, C.sub.6D.sub.6) δ=4.52 (bs, 2H), 2.73 (t, 2H), 2.15 (t, 2H), 1.83 (s, 6H), 1.35 (s, 9H) .sup.13C NMR (150 MHz, C.sub.6D.sub.6) δ=61.62, 51.25, 44.83, 41.73, 30.52 IR (ATR) v/cm.sup.−1=3001, 2961, 2895, 2853, 2812, 1852, 1782, 1728, 1485, 1462, 1429, 1406, 1383, 1352, 1342, 1290, 1238, 1223, 1205, 1184, 1157, 1118, 1101, 1065, 1057, 1014, 1003, 947, 916, 895, 800, 775, 679, 619, 596, 580, 546, 511, 465

(14) Cryoscopic Molecular Weight calcd. for C.sub.8H.sub.21AlN.sub.2 172.25 found 179.06, degree of association=1.04

Example 2a

Synthesis of the Ligand of Compound (Ie-5)

(15) ##STR00031##

(16) A 250 mL round-bottomed flask was charged with 1-(2-chloroethyl)pyrrolidine hydrochloride (24.85 g, 0.146 mol), tert-butylamine (115 mL, 1.1 mol, 6. 3 equiv.), water (5 mL), and heated to gentle reflux at 70° C. for 18 h. After cooling to ambient temperature, hexanes and water (40 mL each) were added and transferred to a separatory funnel. The aqueous fraction was washed with hexanes (3×20 mL) and the combined hexanes fractions were washed with brine, dried over MgSO.sub.4, and evaporated under reduced pressure to yield a slightly red oil that was purified by vacuum distillation at 100° C. and 18 Torr. (14.466 g, 58.1%)

(17) .sup.1H NMR (400 MHz, C.sub.6D.sub.6) δ=2.67-2.56 (m, 4H), 2.39 (t, 4H), 1.59 (p, 4H), 1.07 (s, 9H) .sup.13C NMR (100 MHz, C.sub.6D.sub.6) δ=57.40, 54.55, 50.08, 41.88, 29.64, 24.28

Example 2b

Synthesis of Compound (Ie-5)

(18) ##STR00032##

(19) A 250 mL Schlenk flask was charged with LiAlH.sub.4 (0.925 g, 24.37 mmol), diethyl ether (70 mL), and cooled to 0° C. on an ice bath. A separate 100 mL Schlenk flask was charged with AlCl.sub.3 (1.083 g, 8.12 mmol) and diethyl ether (50 mL). The AlCl.sub.3 solution was cannulated into the LiAlH.sub.4 solution and the resulting cloudy solution stirred at ambient temperature for 30 min. The mixture was cooled to −30° C. and a solution of the ligand of compound (Ie-5) (5.531 g, 32.48 mmol) in diethyl ether (25 mL) was added. The resulting mixture stirred at ambient temperature over 4 h and was then filtered through Celite and evaporated under reduced pressure. When most of the diethyl ether had been evaporated, the flask was cooled on an ice bath to solidify the low-melting product (3.600 g, 56%).

(20) M.P.: 28-29° C.

(21) .sup.1H NMR (600 MHz, C.sub.6D.sub.6) δ=4.47 (bs, 2H), 3.08 (m, 2H), 2.82 (t, 2H), 2.43 (t, 2H), 1.66 (m, 4H), 1.37 (s, 9H), 1.22 (m, 2H)

(22) .sup.13C NMR (150 MHz, C.sub.6D.sub.6) δ=59.45, 54.84, 51.52, 42.99, 30.48, 23.23

Example 3

Synthesis of chlorinated analogue of Compound (Ie-1)

(23) ##STR00033##

(24) A 100 mL Schlenk flask was charged with 1-tert-butylamino-2-dimethylaminoethane (500 mg, 3.47 mmol), toluene (25 mL), and cooled to 0° C. on an ice bath. n-Butyllithium solution (1.39 mL, 3.47 mmol) was added dropwise and the mixture was allowed to stir on the ice bath for 30 min then the ice bath was removed and the mixture warmed to ambient temperature over 2 h. A separate 100 mL Schlenk flask was charged with AlCl.sub.3 (463 mg, 3.47 mmol), toluene (15 mL), and cooled to 0° C. on an ice bath. The ligand solution was then cannulated into the AlCl.sub.3 solution and the resulting mixture warmed slowly to ambient temperature over 3 h before being filtered through Celite and evaporated under reduced pressure to yield an orange solid. Sublimation of the crude (100° C., 50 mTorr) yielded colorless crystals (388 mg, 48%).

(25) M.P.: 87-89° C.

(26) .sup.1H NMR (400 MHz, C.sub.6D.sub.6) δ=2.49 (t, 2H), 1.97 (t, 2H), 1.76 (s, 6 H), 1.27 (s, 9H)

(27) .sup.13C NMR (100 MHz, C.sub.6D.sub.6) δ=60.20, 50.74, 44.92, 39.71, 30.41

Example 4

Synthesis of Compound (III-1)

(28) ##STR00034##

(29) A 200 mL Schlenk flask was charged with AlCl.sub.3 (481 mg, 3.605 mmol) and diethyl ether (40 mL) and cooled on an ice bath. A 100 mL Schlenk flask was charged with LiAlH.sub.4 (410 mg, 10.815 mmol) and diethyl ether (40 mL) and the resulting LiAlH.sub.4 solution was transferred by cannula to the AlCl.sub.3 solution. The resulting diethyl ether solution of AlH.sub.3 (14.421 mmol, 1.1 equiv.) was stirred at ambient temperature for 30 min. A separate 100 mL Schlenk flask was charged with 1,3-diethyl-4,5-dimethylimidazol-2-ylidene (1.996 g, 13.11 mmol), and diethyl ether (20 mL). This solution was then transferred by cannula to the AlH.sub.3 solution that had been re-cooled on an ice bath. The resulting mixture stirred at ambient temperature for 18 h, then the mixture was filtered through Celite, the solids washed with diethyl ether (2×15 mL) and the combined diethyl ether fractions were evaporated under reduced pressure yielding a white powder. (1.960 g, 82%) Purified by sublimation at 110° C., 50 mTorr.

(30) M.P.: 115-116° C.

(31) .sup.1H NMR (600 MHz, C.sub.6D.sub.6) δ=3.82 (q, 4H), 1.26 (s, 6H), 1.01 (t, 6H)

(32) .sup.13C NMR (150 MHz, C.sub.6D.sub.6) δ=124.97, 42.40, 16.61, 7.99

(33) IR (ATR) v/cm.sup.−1 =2967, 2924, 2872, 2818, 1767, 1720, 1639, 1470, 1447, 1420, 1396, 1379, 1356, 1344, 1315, 1298, 1242, 1205, 1159, 1118, 1094, 970, 903, 822, 741, 696, 586, 523, 498

Example 5

Titanium Carbonitride Film Growth from TiCl.SUB.4 .and Compound (Ie-1)

(34) ALD growth of thin films was evaluated using compound (Ie-1) and TiCl.sub.4 on SiO.sub.2 substrates (100 nm thermal oxide on Si) in a Picosun R-75 ALD reactor equipped with a load-lock and ultra-high purity N.sub.2 (<100 ppt H.sub.2O, O.sub.2) as carrier gas. Precursor and co-reactant vapor was pulsed into the deposition chamber sequentially using inert gas valving and separated by purge periods.

(35) Depositions at temperatures above 180° C. produced light gold colored films where were conductive and stable in air.

(36) Self-limiting growth was demonstrated for both precursor and co-reacant at 300° C. by investigating growth rate as a function of precursor and co-reactant pulse length. The top of FIG. 3 demonstrate that growth rate was constant at 1.7 Å/cycle after 250 ALD cycles for pulse lengths ≥0.2 s for TiCl.sub.4 and ≥2.0 s for compound (Ie-1). The observation of self-limiting behavior for compound (Ie-1) was unexpected and surprising, since the film growth temperature of 300° C. is well above its solid-state thermal decomposition temperature of 185° C. Above co-reactant decomposition temperatures, loss of self-limiting growth and increasing growth rate is usually observed. n this case, no film growth was observed in the absence of either precursor or co-reactant even up to 400° C.

(37) Using the saturative pulse scheme of 0.2 s TiCl.sub.4, 5 s compound (Ie-1), and 10 s N.sub.2 purges, growth rate after 250 cycles was evaluated as a function of substrate temperature, as demonstrated by FIG. 3 lower left. Between 220-400° C., growth rate was approximately independent of substrate temperature at 1.6-2.0 Å/cycle. Film resistivities were between 600-650 μΩ.Math.cm across the temperature range 280-400° C. Linear film growth was observed between 75-375 cycles with a growth rate according to linear regression of 1.78 Å/cycle (FIG. 6D). The y-intercept of −16.577 could indicate a slight nucleation delay of about 9 cycles before steady-state growth is reached.

(38) X-ray photoelectron spectroscopy (XPS) was used to determine film composition and revealed the presence of Ti, C, and N with small amounts of O, Cl, and Al as demonstrated in Table 2 below.

(39) TABLE-US-00001 TABLE 2 XPS film composition using TiCl.sub.4 and compound (le-1) Temperature Ti/at % C/at % N/at % Al/at % Cl/at % O/at % 300 38.9 29.0 21.0 3.7 3.9 3.5 400 29.5 31.6 23.5 6.1 2.5 6.9

(40) As demonstrated in FIG. 4, the structure of the films was found to be nanocrystalline TiN/TiC by grazing incidence XRD (GI-XRD) analysis of 40-50 nm films deposited at 280 and 400° C. Low intensity reflections were observed corresponding to the 111 and 200 lattice planes of TiN/TiC.

Example 6

Tungsten Carbide Film Growth from WCl.SUB.6 .and Compound (Ie-1)

(41) Initial ALD film growth trials using WCl.sub.6 and compound (Ie-1) deposited silver-grey films with growth rates between 1.6-1.8 Å/cycle and resistivities between 850-1350 μΩ.Math.cm at growth temperatures of 275-375° C. (FIG. 5). These results were similar to those obtained using TiCl.sub.4 and compound (Ie-1). Film composition based on energy-dispersive X-ray spectroscopy (EDS) consisted of W and C with low Cl and Al content. No N was detected by EDS whereas a clear N signal was observed for films deposited from TiCl.sub.4 and compound (Ie-1). Thus, these films are likely WC.sub.x and not WC.sub.xN.sub.y. It is possible that W metal films are formed at lower temperatures based on the easier reduction of W versus Ti.

Example 7

Aluminum Metal Film Growth from AlCl.SUB.3 .and Compound (Ie-1)

(42) Using AlCl.sub.3 as the metal precursor and with compound (Ie-1) as the reducing agent, Al metal films were deposited at 120° C. The pulse sequence was 2 s AlCl.sub.3 pulse, 20 s N.sub.2 purge, 5 s compound (Ie-1) pulse, 10 s N.sub.2 purge for 125 cycles which deposited a 42 nm film on a Cu substrate (FIG. 6). The sheet resistivity was 1.56 Ω/square which corresponds to a calculated bulk resistivity of 6.5 μΩ.Math.cm, close to the resistivity of bulk Al metal (2.74 μΩ.Math.cm). After 250 cycles, 80 nm thick films deposited on Cu and TiN substrates had sheet resistivities of 0.65 Ω/square and bulk resistivities of 5.0 μΩ.Math.cm.

(43) The as-deposited films are crystalline Al metal according to GI-XRD. FIG. 7 shows the GI-XRD pattern of a 400 nm thick Al film deposited on an SiO.sub.2 (100 nm thermal oxide on Si) substrate with typical 111 and 200 reflections of Al metal.

Example 8a

Synthesis of the Ligand of Compound (Ii-3)

(44) A mixture of 3-dimethylaminopropyl chloride hydrochloride (10.046 g, 0.062 mol), tert-butylamine (30 mL, 0.280 mol), and water (5 mL) was refluxed for 18 h in a 100 mL round bottomed flask. Hexane (25 mL) and water (20 mL) were added to the resultant solution at ambient temperature. The flask contents were transferred to a separatory funnel. The aqueous fraction was washed with hexane (9×25 mL) and the combined organic fractions were dried over anhydrous MgSO.sub.4. The solvent was evaporated under reduced pressure to yield a colorless oil (3.798 g, 39% yield).

(45) .sup.1H NMR (400 MHz, C.sub.6D.sub.6) δ=1.03 (s, 9H), 1.56 (pentet, 2H), 2.11 (s, 6H), 2.26 (t, 2H), 2.55 (t, 2H).

(46) .sup.13C NMR (100 MHz, C.sub.6D.sub.6) δ=29.69, 30.17, 41.48, 46.10, 50.32, 58.85.

Example 8b

Synthesis of Compound (Ii-3)

(47) A solution of AlCl.sub.3 (0.800 g, 6 mmol) in 30 mL of diethyl ether was cannulated into a stirred solution of LiAlH.sub.4(0.719 g, 18 mmol) in 45 mL of diethyl ether at 0° C. in an ice bath. The resultant cloudy solution was warmed to room temperature, stirred for 40 min and re-cooled to −30° C. Then, a solution of [3-(tert-butylamino)propyl]dimethylamine (3.798 g, 24 mmol) in 45 mL of diethyl ether was added dropwise. The resultant mixture was stirred at ambient temperature for 18 h and was then filtered through a 2-cm plug of Celite on a coarse glass frit. The diethyl ether was evaporated from the filtrate under reduced pressure to collect the white semi-solid. The crude product was purified by distillation around 60° C. under reduced pressure affording a colorless oil (1.301 g, 30% yield).

(48) .sup.1H NMR (400 MHz, C.sub.6D.sub.6) δ=1.27 (pentet, 2H), 1.30 (s, 9H), 1.95 (s, 6H), 2.08 (t, 2H), 2.99 (t, 2H).

(49) .sup.13C NMR (100 MHz, C.sub.6D.sub.6) δ=28.79, 31.77, 45.73, 45.82, 53.01, 62.02. IR: v.sub.AlH/cm.sup.−1 1801.