Semiconductor device and image sensor including the same

An image sensor comprising:

• a semiconductor substrate of a first conductivity type;
• a pixel isolation structure provided in the semiconductor substrate to define a pixel region;
• a device isolation layer provided in the semiconductor substrate of the pixel region to define an active region;
• a photoelectric conversion region provided in the pixel region and comprising impurities of a second conductivity type;
• a floating diffusion region spaced from the photoelectric conversion region and provided in the pixel region;
• a transfer gate electrode between the photoelectric conversion region and the floating diffusion region;
• and
• transistors connected to the floating diffusion region,
• wherein at least one of the transistors comprises:
• a gate electrode disposed on the active region;
• a gate insulating pattern between the gate electrode and the active region;
• and
• a first impurity region and a second impurity region provided in the active region at both sides of the gate electrode,
• wherein the gate insulating pattern comprises a first edge portion and a second edge portion adjacent to the device isolation layer, and a center portion between the first and second edge portions,
• wherein the first edge portion has a first thickness, and the second edge portion has a second thickness smaller than the first thickness,
• wherein the first impurity region and the second impurity region are spaced from each other in a first direction,
• wherein the first impurity region comprises a source region and the second impurity region comprises a drain region,
• wherein the gate electrode extends along a second direction perpendicular to the first direction,
• wherein the first edge portion, the second edge portion, and the center portion are extended in the second direction, and
• wherein the first edge portion of the gate insulating pattern and the second edge portion of the gate insulating pattern are opposite to each other in the second direction.

An image sensor comprising:

• a semiconductor substrate of a first conductivity type having a first surface and a second surface facing each other;
• a pixel isolation structure disposed in the semiconductor substrate to define first and second pixel regions;
• photoelectric conversion regions of a second conductivity type provided to the first and second pixel regions, respectively;
• a transfer gate electrode disposed on the first surface of the semiconductor substrate in each of the first and second pixel regions;
• a first device isolation layer defining a first active region on the first surface of the semiconductor substrate in the first pixel region;
• a source follower gate electrode disposed on the first active region;
• a first gate insulating pattern between the source follower gate electrode and the first active region;
• a first impurity region and a second impurity region provided in the first active region at both sides of the source follower gate electrode;
• interconnections electrically connected to the photoelectric conversion regions on the first surface of the semiconductor substrate;
• color filters corresponding to the first and second pixel regions on the second surface of the semiconductor substrate;
• and
• micro lenses on the color filters,
• wherein the first active region includes a channel region overlapping the source follower gate electrode, and the channel region comprises a first edge region adjacent to a first sidewall of the first device isolation layer, a second edge region adjacent to a second sidewall of the first device isolation layer, and an effective channel region between the first edge region and the second edge region,
• wherein the first gate insulating pattern comprises a first edge portion having a first thickness and overlapping the first edge region, and a second edge portion having a second thickness smaller than the first thickness and overlapping the second edge region,
• wherein the first impurity region and the second impurity region are spaced from each other in a first direction,
• wherein the first impurity region comprises a source region and the second impurity region comprises a drain region,
• wherein the source follower gate electrode extends along a second direction perpendicular to the first direction,
• wherein the first edge portion, the second edge portion, and the effective channel region are extended in the second direction, and
• wherein the first edge portion of the first gate insulating pattern and the second edge portion of the first gate insulating pattern are opposite to each other in the second direction.