Control of RIE Etch Profiles And Reactor Contamination by Programmed Temperatures
Original Publication Date: 1991-May-01
Included in the Prior Art Database: 2005-Apr-02
Bartha, J: AUTHOR [+2]
An anisotropic plasma etch process is proposed which, during the etching of deep trenches, provides for a profile change by substrate temperature ramping.
Control of RIE Etch Profiles And Reactor Contamination by
anisotropic plasma etch process is proposed which,
during the etching of deep trenches, provides for a profile change by
substrate temperature ramping.
technology, microstructures are predominantly
produced by dry processes. In many cases, however, it may be
necessary to produce microstructure sidewalls with different slope
angles. An example of this is shown in the cross-sectional view of a
deep trench in the figure. Trenches of this kind, which are
currently used in memory chips, will also be used in future logic
chips. By deposition processes, such a trench must be filled
homogeneously, i.e., without voids. For this purpose, the angle of
the sidewalls must be positive throughout (less than 90o).
Chamfering the upper region ensures that the trench is reliably
filled with, e.g., polysilicon. At the lower end of the trench the
slope angle is also changed. Desirable are rounded trench ends to
minimize substrate stress during oxidation at a later stage.
there are several techniques for producing sidewalls
with variable angles. One technique varies the pressure during
plasma etching, another varies the gas mixture and a further one uses
a multi-step process in the course of which the shape of the mask is
deep trenches with a side wall angle of, e.g.,
88o, techniques are required using a passivation layer to protect the
sidewalls during etching. For a pressure range of about 100 mTorr,