A new process of fabricating inverted-staggered tri-layer thin-film transistors

A new method of fabricating a-Si:H TFT with etching-stop structure has been proposed. Only one plasma-enhanced chemical vapor deposition is required in this new method and a PH/sub 3//H/sub 2/ plasma treatment during the deposition has been used to form the TFT contact and thus saved another plasma deposition. With this method, a TFT of 500 /spl Aring/ active layer has been fabricated successfully. The drain current and saturation mobility of this device is 2.4/spl times/10/sup -7/ A and 0.1 cm/sup 2//V sec, respectively, which is comparable to the conventional fabricating method. The plasma treatment will also form an additional leakage path on the TFT top surface and increase the TFT subthreshold slope. However, a current of less than 1 pA at V/sub G/=-2.4 V can still be obtained. The possible mechanism of the contact formation by the plasma treatment is also discussed.<
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