Qualification of Resist Strip Process for Ultra Low-k/Cu Interconnect

Abstract:

• Periodical: Solid State Phenomena (Volumes 103-104)
• Pages: 345-348
• DOI: https://doi.org/10.4028/www.scientific.net/SSP.103-104.345
• Online since: April 2005
• Authors: Han Xu, Amy Shen, Vlad Tarasov, Brian White, Josh Wolf
• Keywords: Low-k Dielectric, OSG, p-MSQ, Porous Low-k, Residue Clean, Resist Strip, Ultra Low-k

References

[1] H. Xu, T. Jacobs, B. White and P. J. Wolf: Proceeding to 14th Annual IEEE/SEMI Advanced Semiconductor Manufacturing Conference and Workshop, Munich, Germany, 2003.

[2] W. Chen, K. Sugita, Y. Morikawa, S. Yasunami, T. Hayashi and T. Uchida, JVST A 19 (2001), p.2936.

[3] N. Kobayashi, 6th International Forum on Semiconductor Technology, California, (2003)

[4] A. E. Braun, Semiconductor International, October 2002 Low High Low High Low High Low High Low High Low High Low High Low High Low High Low High Low High Low High Figure 2: Results of 5 factor screening DOE to optimize ashrate rate and uniformity. Figure 3: Top-down SEM shows top surface is free from any residue after ULVAC's WCP resist ash process. 0 20 40 60 80 100 -14 -13 -12 -11 -10 Log Bridging Current Distribution (%) ULVAC N2-H2 POR N2-H2 Dielectric Etcher WCP Figure 5(c): Bridging current comparison between POR (etch chamber) and ULVAC's WCP process. Figure 4: Cross-section SEM shows that there is more corner rounding of the cap layer after resist strip in a typical dielectric etch chamber. 0 25 50 75 100 1000 1500 2000 2500 3000 RC Product (nanosec) % Distribution POR ULVAC 0 20 40 60 80 100 1.00E-12 1.00E-11 1.00E-10 Comb Capacitance (F) Distribution (%) ULVAC N2-H2 POR N2-H2 Figure 6: RC product distribution comparison between POR (etch chamber) and ULVAC's WCP process. Figure 5(a): Comb capacitance comparison between POR (etch chamber) and ULVAC's WCP process. Low WCP Powe r High WCP Powe r Low WCP Powe r High WCP Powe r 0 20 40 60 80 100 1.00E+05 1.00E+06 Serpentine Line Resistance (Ω) Distribution (%) ULVAC N2-H2 POR N2-H2 Figure 7: Post CMP FIB SEM shows the effect for WCP power to the formation of voids in low-k film. Figure 5(b): Serpentine line resistance comparison between POR (etch chamber) and ULVAC's WCP process. 0 25 50 75 100 1000 1500 2000 2500 3000 RC Product (nanosec) % Distribution ULVAC Diluted O2 POR ULVAC N2/H2 Figure 8: RC product distribution comparison between N2/H2 and diluted O2 processes. 0 25 50 75 100500 1000 1500 2000 RC Product (nanosec) % Distribution After O2 conditioning After resist strip Figure 9: RC product distribution comparison for difference chamber conditions.