In-situ multi-layer dielectric films for application as gate spacer and etch stop layers

A method of forming a spacer in a transistor, comprising:

• performing a deposition cycle, comprising:
• flowing an oxygen source into a chamber;
• flowing a carbon source into the chamber;
• flowing a nitrogen source into the chamber;
• and
• flowing an oxygen source into the chamber;
• and
• repeating the deposition cycle a plurality of times.

A transistor, comprising:

• a pair of spacers, wherein both of the spacers comprise:
• a composition gradient from a first surface to a second surface, wherein the composition gradient has a first oxygen concentration at the first surface, a second oxygen concentration at a midpoint of the spacer between the first surface and the second surface, and a third oxygen concentration at the second surface, wherein the second oxygen concentration is greater than the first oxygen concentration and the third oxygen concentration;
• a channel region between the pair of spacers;
• and
• a gate stack over the channel region.

An electronic system, comprising:

• a board;
• a package substrate coupled to the board;
• a die coupled to the package substrate, wherein the die comprises:
• a channel region;
• a gate stack over the channel region;
• a first spacer on a first end of the gate stack;
• and
• a second spacer on a second end of the gate stack, wherein the first spacer and the second spacer comprise:
• a first surface adjacent to the gate stack;
• a second surface spaced away from the gate stack;
• and
• a bulk layer between the first surface and the second surface, wherein a dielectric constant of the bulk layer is lower than dielectric constants of the first surface and the second surface.