Resistance to sulfonylurea herbicides, including bensulfuron-methyl, pyrazosulfuron-ethyl, imazosulfuron and ethoxysulfuron, was discovered in naturally occurring populations of Lindernia micrantha D. Don in rice ®elds that had been treated with sulfonylurea-based herbicides for 3±7 consecutive years. The resistant biotype was approximately 80»300 times more resistant than the susceptible one to the above four sulfonylurea herbicides. This is the second con®rmed occurrence of herbicide resistance resulting from the use of sulfonylurea herbicides in Japan. Several herbicides with dierent modes of action, including pretilachlor, cafenstrole, bifenox, naproanilide, thiobencarb + simetryn + MCPB, MCPA-thioethyl + simetryn and cyhalofop-butyl + bentazone, eectively controlled the resistant biotype in pot trials.

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Because of the poor step coverage of TiN film by sputter and plasma CVD, the blanket-W for contact plug can not be used beyond 256Mbit-DRAMS. Although a thermal LPCVD-TiN using titanium tetrachloride (TiCb)-ammonia ( "3) realizes a conformal deposition, deposition temperature is too high for devices use (> 700°C) El]. We have developed, for the first time, methylhydrazine (MH) -reduced TiN-CVD and succeeded in realizing a low-temperature (e 500°C) TiN film with a low chlorine (Cl) concentration that can fill a 0.2 pn contact hole.A commercial single-wafer LPCVD reactor was used in these experiments. The methylhydrazine [(CH3)HNNH2: MH, m.p.= -80°C, b.p.= 87"C, vapor pressure= 49.6 TOIT/ 25"C] was used as a reduction gas. Wafer was heated from back-side using infrared heater at temperature from 400 to 500OC. Contact resistance was measured using the Kelvin method and the junction leakage current of Si (n+)/Si @-) diode was measured. Sputter Ti film of 300A was used as a contact metal to Si.The deposition rate of h4H-reduced TiN showed a mass transport-limited reaction, increasing with the MH flow rate, and was several order of magnitude higher than that of "3-reduction ( Fig. 1). The high reactivity of MH chemistry agreed with our previous study [2]. The film deposited at 400°C showed a typical 6 phase of TiN structure (Fig. 2).The resistivity decreased as the deposition temperature increased, approaching to 90 p W m at 500°C (Fig. 3). This value was lower than that of MOCVD [3] and was obtained by "3-reduction above 70O0C, as shown in Figure 3. The C1 concentration in TiN film decreased as deposition temperature increased, with a tendency similar to the film resistivity (Fig. 4). The MH-reduced TiN film deposited at 450°C did not generate the A1 corrosion even after exposing to moisture for 168 hours due to the low C1 concentration while the NH3-reduced TiN film generated it (Fig. 5). The A1 corrosion was caused by residual C1 above 3 x 1021 atoms/cm3 in TiN film, as shown by hatched region in Figure 4.The thickness ratio at the bottom to the top was above 70% for the deposition for 0.4 pm contact hole ( Fig. 6-a). Even 0.2 pm contact hole was completely filled with TiN film (Fig. 6-b). This suggests that the TiN film can be used for giga-bit interconnects alternated to blanket-W contact filling.The contact resistance for Si (n+) and Si (p+) using blanket-W/MH-reduced TiN electrode was similar to that of the reference (blanket-WPVD-TiN) (Fig. 7). The specific contact resistance for Si (n+) and Si (p+) was 1.9 x 10-7 Q.cm2 and 6.9 x 10-7 Q.cm2, respectively. The junction leakage current for both the experiment and reference was in the order of lo-" A at 5 V (Fig. 8). Thus, MHreduced TiN film did not damage Si contact and acted as a barrier layer for chemical etching during blanket-W deposition.We have succeeded in filling the 0.2 pm-contact by TiN using MH-reduction of Tick. The Tick-MH reaction proves the capability of low-temperature, low-resistivity, and no-damage contact metallization. The 0.2 pm contact fill...