Mumbai University > Electronics Engineering > Sem 8 > MEMS Technology

Marks: 3M

Topography on the surface of the wafer, such as deep cavities and trenches, are common in MEMS and pose challenges to both resist. Spinning and imaging.

For cavities deeper than about 10 µm, thinning of the resist at corners and accumulation inside the cavity create problems with exposure and with learing insufficient resist thickness during etches.

Exposing a pattern on a surface with height variations in excess of 10 µm is also a difficult task because of the limited depth of focus.

Contact and proximity tools are not suitable for this task unless a significant loss of resolution is tolerable.

Where the no. of height level is limited (<3) projection lithography can be used. To perform

Exposure with focus adjustment at each of these height levels but it is costly.