lowetchrate

Low etch rate refers to an etching process in which removal of material proceeds slowly, typically measured in nanometers per minute or micrometers per minute. Such slow removal is often intentional to achieve precise feature transfer, good depth control, and compatibility with underlying layers.

Low etch rates appear in both wet chemical etching and dry etching (such as plasma or reactive ion etching). They contrast with high-etch-rate processes that prioritize throughput. The term describes the rate, not the etchant’s chemical class.

Factors influencing etch rate include etchant composition and concentration, temperature, pressure and power in plasma processes, gas chemistry, agitation, and the material’s bonding energy and crystal orientation. Additives or passivation layers can deliberately slow removal to improve selectivity or anisotropy.

Implications: lower rates can yield better depth control, uniformity, and selectivity, but increase processing time and cost. In manufacturing, achieving a low etch rate requires careful calibration and monitoring of etch time, to avoid under- or over-etching.

Measurement and control: etch rate is determined by comparing substrate thickness before and after etching, using profilometry, interferometry, or ellipsometry, and may be tracked in situ with optical sensors. Applications include thin-film thinning, delicate pattern transfer, and MEMS fabrication where precision outweighs speed.