AST-provide RF magnetic sputtering equipment

The surface Acustic components, owing to a wide range of frequency from 10 MHz to 30 GHz besides being compact, low cost, resilient and easy to produce, have been widely adopted in wireless phones, cell phones and micro satellite communications. A case in point taking to a surface oscillation component adopted in the frequency range of a 1.5GHz cell phone system with a crosstalk electrode pitch rated at between 0.6 and 0,7μm, it is inevitable that the 0.35μm depth micro-electrode design would need to be further refined when the pitch is narrowed to between 0.4 to 0.5μm for improved oscillation filtration taken into account the distortion from insertion, deterioration versus the dependability of having chosen such option.

With the physical bulk of a host of wireless communication products keep shrinking in size, the future trend would dictate that all components be converted into chipsets and condensed circuitries. Yet not as a voltage-rated material that cannot be applied to surface Acustic components, the silica substrate would need to be sputtered with a coat of electrically charged membrane to serve the purpose. While common electrically charged membrane often comes in the form of ZnO and AIN that come with their pros and cons in that ZnO's electromechanical coupling factor is three times higher than that of AlN, but AlN's oscillation twice that of ZnO.

(1).Optimized parameters in RF magnetic sputtering for fabricating ZnO membrane (taken to C axis at (002) and at a high impedance ratio)
1. A substrate-target pitch rated at 50mm.

2. Sputter pressure: 3m torr.

3. Unheated substrate at 80 deg. C, with RF at 150W.

a. The higher the temperature, the more favorable the vapor process will diffuse to form a layered structure.
b. The lower the temperature, the higher the success rate of crystallization gravitating toward the C axis.
c. The slower the sputtering rate, the lesser the defects would be.
d. A reverse correlation between temperature and sputtering rate.

4. Oxygen/argon gas ratio: 2:3.
The higher the oxygen ratio, the slower the rate would become in light that ZnO formation on the target slows down if oxygen content increases, resulting in reduced particle energy gravitating toward C axis.

5.The higher the frequency, the finer the schematic pitch on the substrate has to be, or else the electrode may tend to be shorted disabling the component following an underrated impedance rating on the electrically charged substrate as the intermittent electromagnetic filed increases. Hence besides having the right gravitational axis in the multiplication process, it is also essential to improve the membrane's impedance rate suited for high-frequency component applications of high power, high success rate, Zn moderation and low impedance resistance.

6. Relying on internal stress accumulated from the sputtering process at a curing temperature of 600 to 800 deg. C, the energy-charged heated atoms would move to release the internal stress to facilitate surface oscillation component applications.

(2).Optimized parameters in RF magnetic sputtering for fabricating AIN membrane (taken to a Corning 7059 fiber glass, GaAs or Si substrate) :
1. The substrate and the target would both need to undergo pre-rinse.
2. The sputtering rate needs to be controlled to within 1.1 to 1.5μm/ hour.
3. The RF factor is at approx. 300 watts when working with a 3-inch target material.
4. The nitrogen/argon gas ratio is at approx. 1:3 with a total gas flow of 12 sccm.
5. A process operating pressure rated at 7.5mtorr.
6. A substrate temperature rated at approx. 350 deg. C.
7. A substrate-target pitch rated at approx. 65 mm.