Method of forming trench in semiconductor substrate
The present invention provides a method of forming a trench in a semiconductor substrate. First, a first patterned mask layer is formed on a semiconductor substrate. The first patterned mask layer has a first trench. Then, a material layer is formed along the first trench. Then, a second patterned mask layer is formed on the material layer to completely fill the first trench. A part of the material layer is removed when the portion of the material layer between the second patterned mask layer and the semiconductor substrate is maintained so as to form a second trench. Lastly, an etching process is performed by using the first patterned mask layer and the second patterned mask layer as a mask.
1. A method of forming a trench in a substrate, comprising:
providing a substrate;
forming a first patterned mask layer on the substrate, wherein the first patterned mask layer has a first trench;
forming a material layer comprehensively on the substrate, wherein the material layer is formed on a bottom surface and at least a sidewall of the first trench;
forming a second mask layer on the material layer to completely fill the first trench;
completely removing the second mask layer outside the first trench to keep the second mask layer filled in the first trench to form a second patterned mask layer;
removing a portion of the material layer and maintaining the portion of the material layer between the second patterned mask layer and the substrate to form at least a second trench between the first patterned mask layer and the second patterned mask layer; and
after forming the second trench, performing an etching process by using the first patterned mask layer and the second patterned mask layer as a mask.
2. The method of forming a trench in the substrate according to claim 1 , wherein the etching process is to remove the substrate exposed by the second trench so as to form at least a third trench in the substrate.
3. The method of forming a trench in the substrate according to claim 1 , after forming the second trench, further comprising:
forming at least a second spacer on a sidewall of the second trench to form a fourth trench in the second trench; and
removing the substrate exposed by the fourth trench.
4. The method of forming a trench in the substrate according to claim 1 , wherein the second patterned mask layer has an etching selectivity with respect to the material layer.
5. The method of forming a trench in the substrate according to claim 1 , wherein before forming the first patterned mask layer, further comprising: forming a third mask layer on the substrate.
6. The method of forming a trench in the substrate according to claim 5 , wherein the etching process is to remove the third mask layer exposed by the second trench to form a third patterned mask layer having a fifth trench.
7. The method of forming a trench in the substrate according to claim 6 , after forming the third patterned mask layer, further comprising:
removing the substrate exposed by the fifth trench.
8. The method of forming a trench in the substrate according to claim 6 , after forming the third patterned mask layer, further comprising:
forming at least a fifth spacer on a sidewall of the fifth trench to form a sixth trench in the fifth trench.
9. The method of forming a trench in the substrate according to claim 8 , further comprising removing the substrate exposed by the sixth trench.
10. The method of forming a trench in the substrate according to claim 8 , further comprising:
removing the third patterned mask layer; and
etching the substrate by using the fifth spacer as a mask.
11. The method of forming a trench in the substrate according to claim 6 , wherein the third patterned mask layer has an etching selectivity with respect to the first patterned mask layer and the second patterned mask layer.
12. The method of forming a trench in the substrate according to claim 1 , wherein the first patterned mask layer and the second patterned mask layer comprise the same material.