Method for fabricating semiconductor structure
A method for fabricating semiconductor structure is provided. A substrate having a plurality of blocks is provided. Each of the blocks includes a first region and a second region. The first region and the second region are disposed alternately. A plurality of composite layers is formed on the substrate. The top-most layer of the composite layers is patterned. A plurality of composite blocks is formed on the first region of the substrate. The composite layers and the composite blocks on the blocks are removed successively by a removal process. A staircase structure is formed on the substrate.
1. A method for fabricating semiconductor structure, comprising:
providing a substrate, the substrate comprising a plurality of blocks, each of the blocks respectively comprising a first region and a second region, the first region and the second region being disposed alternately;
forming a plurality of composite layers on the substrate;
patterning the top-most layer of the composite layers, so as to form a plurality of composite blocks on the first regions of the substrate; and
successively removing the composite layers and the composite blocks on the blocks by a removal process, so as to form a staircase structure on the substrate, wherein a method for successively removing the composite layers and the composite blocks on the blocks by the removal process comprises:
forming a photoresist layer on the substrate, the photoresist layer covering the composite layers and the composite blocks on one block;
removing the composite layers and the composite blocks not covered by the photoresist layer, so as to form the staircase structure on the substrate; and
repeating the removal process, wherein for each repetition of the removal process, the photoresist layer further covers the composite layers on one more block.
2. The method for fabricating semiconductor structure as recited in claim 1 , wherein the composite layers are N layers, and the number of times of performing the removal process is N/2−1, wherein N≧2 and N is an even number.
3. The method for fabricating semiconductor structure as recited in claim 1 , wherein the composite layers are N layers, and the number of times of performing the removal process is (N+1)/2−1, wherein N≧2 and N is an odd number.
4. The method for fabricating semiconductor structure as recited in claim 1 , wherein the number of the composite layers covered by the photoresist layer is two more than the number of the composite layers that are previously covered by the photoresist layer.
5. The method for fabricating semiconductor structure as recited in claim 1 , wherein the method for removing the composite layers not covered by the photoresist layer comprises simultaneously removing two of the composite layers.
6. The method for fabricating semiconductor structure as recited in claim 1 , wherein the method for removing the composite layers and the composite blocks not covered by the photoresist layer comprises simultaneously removing each of the composite blocks and the composite layer located under each of the composite blocks.
7. The method for fabricating semiconductor structure as recited in claim 1 , wherein the method for forming the composite blocks on the first regions of the substrate comprises:
forming a mask layer on the composite layers of the first regions;
removing parts of the top-most layer of the composite layers not covered by the mask layer; and
removing the mask layer, so as to form the composite blocks on the first regions of the substrate.
8. The method for fabricating semiconductor structure as recited in claim 1 , wherein the composite layers are N layers, and the number of photomask required for performing the removal process is at least N/2−1, wherein N≧2 and N is an even number.
9. The method for fabricating semiconductor structure as recited in claim 1 , wherein the composite layers are N layers, and the number of photomask required for performing the removal process is at least (N+1)/2−1, wherein N≧2 and N is an odd number.
10. The method for fabricating semiconductor structure as recited in claim 1 , wherein the composite layers comprise a conductor layer, a semiconductor layer, a dielectric layer, or a combination thereof.
11. The method for fabricating semiconductor structure as recited in claim 1 , wherein each of the composite layers comprises a conductor layer and a dielectric layer, and the conductor layers in two adjacent composite layers are electrically isolated by the dielectric layer.
12. The method for fabricating semiconductor structure as recited in claim 11 , wherein the staircase structure comprises a plurality of exposed surfaces, and each of the exposed surfaces exposes a part of the dielectric layer.
13. The method for fabricating semiconductor structure as recited in claim 1 , wherein the staircase structure comprises a plurality of stairs, and a width of each of the stairs is equal to a width of each of the first regions of the substrate.