Non-destructive inter-level dielectric via in-line process monitoring by atomic force microscopy
A new application using atomic force microscopy (AFM) for in-line process control monitoring (PCM) of an interlevel dielectric via etching step is reported. The AFM with its near atomic-level resolution is capable of nondestructively measuring whether micron-sized vias have been etched to completion. Etch completion is determined by comparing the AFM measured etch depth of adjacent via holes through {approximately}4000 {Angstrom} thick Si{sub 3}N{sub 4} over Au-based ohmic and W gate metallizations. Due to etch selectivity, of the SF{sub 6}/0{sub 2} reactive ion etch (RIIE) generated plasma, the ohmic metal acts as an etch stop whereas the W-based refractory gate continues to etch. For etch times beyond endpoint in the range of 20 to 50%, the AFM measured via etch depth differences is 250 to 400 {Angstrom} when comparing via depths over ohmic metal and W gate metal. This etch depth difference is a specific marker for etch completion and it is measured nondestructively at a point in the process where rework is still a feasible option.
- Research Organization:
- Sandia National Labs., Albuquerque, NM (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC04-94AL85000
- OSTI ID:
- 29436
- Report Number(s):
- SAND--94-2823C; CONF-9505189--1; ON: DE95008516
- Country of Publication:
- United States
- Language:
- English
Similar Records
Dry etch development of W/WSi short Gate MESFETs
Plasma etching of refractory metals (W, Mo, Ta) and silicon in SF/sub 6/ and SF/sub 6/-O/sub 2/. An analysis of the reaction products