1：Experimental Design and Method Selection:

The study uses a galvanic etch method with patterned backside platinum electrodes to improve uniformity. The rationale is to mimic the frontside silicon pattern on the backside to provide a consistent etch current. Theoretical models include electrochemical cell principles and electric field considerations.

2：Sample Selection and Data Sources:

Silicon wafers are 525 μm thick, 1-10 ?·cm, boron doped, with Si3N4 protective layers. Patterns are applied using photolithography. Data sources include SEM and profilometry for depth measurements.

3：List of Experimental Equipment and Materials:

Equipment includes Karl Suss aligner for backside alignment, reactive ion etcher, sputter deposition system for platinum, ion milling system, optical profilometer (Veeco WYKO NT1100), stylus profilometer (Ambios Technology, Inc. XP-2), SEM. Materials include silicon wafers, Si3N4, photoresist (EMB Performance Materials AZ5214), platinum, HF, EtOH, H2O2, NaOH.

4：Experimental Procedures and Operational Workflow:

Steps involve patterning frontside and backside with photoresist and Si3N4 removal, optional MEMS integration, platinum deposition and patterning via ion milling, galvanic etching in HF:EtOH:H2O2 solution for 10-20 minutes, rinsing, drying, and depth measurement after porous silicon removal with NaOH.

5：Data Analysis Methods:

Depth variation is calculated using a formula (depthd - depths)/depths * 100. Profilometry and SEM are used for quantitative analysis.