میکروفن خازنی با اندازه کوچک و حساسیت بالا با به کار گیری دیافراگم دایروی با مرکز ثابت

محورهای موضوعی : ادوات نیمه هادی

نسترن نادمی ¹ (کارشناس ارشد - دانشکده مهندسی برق – واحد تهران جنوب، دانشگاه آزاد اسلامی، تهران، ایران)
جواد کرمدل ² (دانشیار - دانشکده مهندسی برق – واحد تهران جنوب، دانشگاه آزاد اسلامی، تهران، ایران)

تاریخ دریافت : 1394/02/15 تاریخ پذیرش : 1394/09/28 تاریخ انتشار : 1394/11/01

کلید واژه: میکروفن خازنی, ولتاژ کششی, مبدل های صوتی, الکترواستاتیکی, سیستمهای میکرو الکترومکانیکی (MEMS),

چکیده مقاله :

در این مقاله، یک میکروفن خازنیMEMS جدید تک تراشه بر روی ویفر سیلیکونی با کمینه کردن اندازه و کاهش استحکام مکانیکی با استفاده از دیافراگم دایروی با مرکز ثابت پیشنهاد شده است. در میکروفن پیشنهادی دیافراگم شامل تعدادی حفره می‌باشد که موجب عبور هوا در شکاف مابین صفحه پشتی و دیافراگم می‌شود و به این ترتیب میرائی مربوط به صدا را در میکروفن کاهش می‌دهد. ‌تازگی این روش، ایجاد میکروفن دایروی با مرکز ثابت می‌باشد که قطر دیافراگم کمتر از میکروفن خازنی مرسوم به دست می‌آید. ابتدا تحلیل مکانیکی روی دیافراگم میکروفن انجام می‌گیرد تا ولتاژ کششی به دست آید. ولتاژ کششی میکروفن دایروی پیشنهادی 14 ولت می‌باشد. با توجه به ولتاژ کششی بدست آمده٬ ولتاژ بایاس به میکروفن اعمال شده و پارامترهای مختلف مانند ظرفیت خازنی و حساسیت اندازه‌گیری شد. با توجه به نتایج شبیه‌سازی کامسول (COMSOL)، میکروفن پیشنهادی با دیافراگم به قطر 400 میکرومتر و ضخامت 5/1 میکرومتر، حساسیت‌ 23- دسی‌بل را نشان داد. در مقایسه با کارهای قبلی، میکروفن پیشنهادی با ولتاژ تغذیه کمتر عملکرد فرکانسی بهتر و حساسیت بیشتری را برای سنس نمودن صدا عرضه می‌کند

چکیده انگلیسی:

In this paper, a new single-chip MEMS capacitor microphone on a silicon wafer by minimizing the size and the reduction of mechanical strength using a circular diaphragm with a fixed center is proposed. In the proposed microphone, the diaphragm includes a number of holes to pass the air through the gap between the back plate and diaphragm, and thus reduces the damping of the sound from the microphone. Novelty of this method, creating a circular microphone with fixed center, which the diameter of diaphragm is less than the conventional condenser microphone. At first, the mechanical analysis was conducted on microphone diaphragm in order to achieve the pull-in voltage. The pull-in voltage of the proposed circular microphone is 14 volts. According to the obtained pull-in voltage, the bias voltage were applied to the microphone, and various parameters such as capacitance and sensitivity were measured. Based on the simulation results of COMSOL, the proposed microphone with diaphragm diameter of 400 μm and a thickness of 1.5 μm, the sensitivity of -23 dB is shown. In comparison with previous works, the proposed microphone with lower supply voltage is provided the better frequency performance, and higher sensitivity, in order to sense the sound.

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