Metal oxide layer composition control by atomic layer deposition for thin film transistor

A method comprising:

• providing a substrate;
• depositing by atomic layer deposition (ALD) a first metal oxide in a first deposition cycle;
• depositing by ALD a second metal oxide in a second deposition cycle;
• and
• forming a multi-component metal oxide semiconductor thin film on the substrate over a plurality of first deposition cycles and second deposition cycles in a deposition sequence, wherein the first deposition cycles occur with increasing frequency during the deposition sequence.

An apparatus, comprising:

• a substrate;
• and
• a thin film transistor (TFT) over the substrate, the TFT comprising:
• a gate metal over the substrate;
• a dielectric layer over the substrate and the gate metal;
• an oxide semiconductor layer over the dielectric layer, wherein the oxide semiconductor layer has a source region, a drain region, and a channel region, wherein the channel region is between the source region and the drain region, and wherein the oxide semiconductor layer includes at least two metal oxides, the at least two metal oxides having a varying concentration relative to one another between a lower surface and an upper surface of the oxide semiconductor layer;
• a source metal adjacent to the source region of the oxide semiconductor layer;
• and
• a drain metal adjacent to the drain region of the oxide semiconductor layer.

An apparatus, comprising:

• a substrate;
• and
• a thin film transistor (TFT) over the substrate, the TFT comprising:
• an oxide semiconductor layer over the substrate, wherein the oxide semiconductor layer has a source region, a drain region, and a channel region, wherein the channel region is between the source region and the drain region, and wherein the oxide semiconductor layer includes at least two metal oxides, the at least two metal oxides having a varying concentration relative to one another between a lower surface and an upper surface of the oxide semiconductor layer;
• a dielectric layer over the channel region of the oxide semiconductor layer;
• a gate metal over the dielectric layer;
• a source metal adjacent to the source region of the oxide semiconductor layer;
• and
• a drain metal adjacent to the drain region of the oxide semiconductor layer.