Improved TMAH Si-etching solution without attacking exposed aluminum

Gui zhen Yan, Philip Ching Ho Chan, I. Ming Hsing, Rajnish K. Sharma, Johnny K O Sin

Research output: Chapter in book / Conference proceedingConference article published in proceeding or bookAcademic researchpeer-review

28 Citations (Scopus)


In this paper, an improved Tetramethyl Ammonium Hydroxide (TMAH) etching method is reported. The process features higher silicon etching rate and resulting in smooth silicon surface and at the same time, no significant aluminum etching is observed. We believe that after TMAH etching the aluminum surface are protected by the coating of by-products, which prevents etching the underlying aluminum films by the TMAH solution. The etchant used in the study consists of 5 wt.% TMAH solution, 1.4 wt.% (or above) dissolved silicon, and 0.4-0.7 wt.% (NH4)2S2O8 oxidant additive. Silicon etching rate of 0.9-1.0 μm/min and zero aluminum etching rate is be achieved using the process. Moreover the silicon surface remains smooth after etching. The etching process demonstration in this work is readily applicable to MEMS device fabrication such as removing polysilicon like sacrificial layer removal after metallization is completed.
Original languageEnglish
Title of host publicationProceedings of the IEEE Micro Electro Mechanical Systems (MEMS)
Number of pages6
Publication statusPublished - 1 Jan 2000
Externally publishedYes
Event13th Annual International Conference on Micro Electro Mechanical Systems (MEMS 2000) - Miyazaki, Japan
Duration: 23 Jan 200027 Jan 2000


Conference13th Annual International Conference on Micro Electro Mechanical Systems (MEMS 2000)

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Electrical and Electronic Engineering
  • Mechanical Engineering

Cite this