Methods for solving epitaxial growth loading effect at different pattern density regions

A method for reducing an epitaxial growth loading effect in a patterned device, the method comprising:

• forming a first trench and a second trench in a substrate and in a first insulating layer over the substrate to form a low pattern density region and a high pattern density region, wherein the first trench has a larger cross-sectional area than the second trench;
• isolating the first trench from the second trench by using a first mask;
• disposing a second insulating layer in the first trench;
• removing a portion of the first mask in order to expose the second trench;
• and
• growing an epitaxial layer in the second trench.

A method for fabricating a patterned device, the method comprising:

• forming a first trench and a second trench in a substrate and in a first insulating layer over the substrate to form a low pattern density region and a high pattern density region, wherein the first trench has a larger cross-sectional area than the second trench;
• disposing a first mask above the first insulating layer covering the first trench and the second trench;
• patterning a second mask above the low pattern density region in order to expose the first mask;
• removing at least a portion of the first mask in order to expose the first trench;
• disposing a second insulating layer in the first trench;
• removing a further portion of the first mask in order to expose the second trench;
• and
• growing an epitaxial layer in the second trench.