1. A method of fabricating a three-dimensional (3D) semiconductor device comprising:
forming a stack structure including a plurality of horizontal layers and a plurality of interlayer insulating layers alternately stacked on a substrate, the substrate including a cell array region and a contact region;
forming a first mask pattern covering the cell array region, the first mask pattern defining openings extending in one direction over the contact region;
performing a first etching process with a first etch-depth using the first mask pattern as an etch mask on the stack structure;
forming a second mask pattern covering the cell array region and exposing a part of the contact region; and
performing a second etching process with a second etch-depth using the second mask pattern as an etch mask structure on the stack structure, the second etch-depth being greater than the first etch-depth,
after performing the second etching process, repeatedly performing a process of shrinking a planar area of the second mask pattern and performing the second etching process using the shrunk second mask pattern as the etch mask structure.
2. A method of fabricating a three-dimensional (3D) semiconductor device comprising:
forming a stack structure including a plurality of horizontal layers sequentially stacked on a substrate,
the substrate including a cell array region and a contact region;
forming a first mask pattern covering the cell array region,
the first mask pattern defining openings extending in one direction over the contact region;
performing a first etching process with a first etch-depth using the first mask pattern as an etch mask on the stack structure,
the performing the first etching process including etching a part of the stack structure exposed by the first mask pattern to the first etch-depth using the first mask pattern as the etch mask, and
the first etch-depth corresponds to a vertical pitch of one of the plurality of horizontal layers; and
forming a second mask pattern covering the cell array region and exposing a part of the contact region;
performing a second etching process with a second etch-depth using the second mask pattern as an etch mask structure on the stack structure,
the second etch-depth being greater than the first etch-depth,
the performing the second etching process including
etching a portion of the stack structure exposed by the second mask pattern to the second etch-depth using the second etch pattern as the etch mask structure, and
the second etch-depth corresponds to at least twice the vertical pitch of one of the plurality of horizontal layers.
3. The method of claim 1, wherein the performing the first etching process comprises forming horizontal patterns by anisotropically etching an uppermost horizontal layer of the plurality of horizontal layers in the stack structure.
4. The method of claim 3, wherein the performing the second etching process comprises removing an outermost one of the horizontal patterns.
5. The method of claim 1, wherein
the number of the horizontal layers in the stack structure is 2N,
N is a natural number, and
the second etching process is repeatedly performed N\u22121 times.
6. The method of claim 1, wherein the repeatedly performing the process of shrinking the planar area of the second mask pattern includes laterally moving a sidewall of the second mask pattern by twice a width of the opening of the first mask pattern.
7. The method of claim 1, wherein the forming the first mask pattern on the stack structure occurs after the repeatedly performing the process of shrinking the planar area of the second mask pattern and the second etching process.
8. The method of claim 7, wherein performing the first etching process comprises anisotropically etching even-numbered horizontal layers of the stacked horizontal layers in the stack structure by using the first mask pattern as the etch mask.
9. The method of claim 1, wherein
the cell array region is adjacent to the contact region in a second direction,
the substrate includes a dummy region,
the cell array region is adjacent to the dummy region in the first direction,
the second direction is perpendicular to the first direction,
the first mask pattern covers the dummy region, and
the second mask pattern exposes a portion of the dummy region.
10. A method of fabricating a three-dimensional (3D) semiconductor device comprising:
forming a stack structure including a plurality of horizontal layers stacked on a first region and a second region of a substrate,
the plurality of horizontal layers including odd horizontal layers alternately stacked with even horizontal layers;
performing one of a first process and a first method on the stack structure,
the first process including,
forming a mask on the first and second regions of the substrate,
the mask defining a plurality of openings that are spaced apart from each other over the second region of the substrate, and
etching through at least one of the even horizontal layers using the mask as an etch mask structure on the stack structure without substantially etching one of the odd horizontal layers,
the first method including,
forming a mask pattern on the first and second regions of the substrate,
the mask pattern exposing a part of the second region of the substrate,
etching through at least a pair of the plurality of horizontal layers using the mask pattern as an etch mask pattern on the stack structure,
each pair of the plurality of horizontal layers including one of the even horizontal layers that is adjacent to one of the odd horizontal layers; and
performing an other of the first process and the first method on the stack structure.
11. The method of claim 10, wherein the performing the first process occurs before the performing the first method.
12. The method of claim 10, wherein the performing the first method occurs before the performing the first process.
13. The method of claim 10, wherein the first method includes:
after performing the second etching process a first time, repeatedly performing a shrinking-and-etch process including,
shrinking a planar area of the mask pattern so more of the second region of the substrate is exposed,
repeating the etching through at least a pair of the plurality of horizontal layers using the shrunken mask pattern as the etch mask pattern.
14. The method of claim 13, wherein the stack structure includes a plurality of interlayers alternately stacked in between the plurality of horizontal layers.
15. The method of claim 1, wherein the part of the contact region exposed by the second mask pattern includes a part of an area of the contact region exposed by the first mask pattern.
16. The method of claim 1, wherein the openings defined by the first mask are spaced apart from each other in a second direction perpendicular to the first direction.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A fluid dynamic bearing system used particularly for a spindle motor having a shaft (1; 101) that is accommodated in a bearing bush (2; 102) and rotatably supported with respect to the bearing bush,
characterized in that the bearing bush (2; 102) is made of plastics.
2. A fluid dynamic bearing system according to claim 1, characterized in that an elastic element (4) is disposed at outside circumference of the bearing bush (2) by means of which the bearing bush is held in a sleeve (3) or in a baseplate (9) of a spindle motor.
3. A fluid dynamic bearing system according to claim 2, characterized in that the elastic element (4) is given the form of an elastic coating on the bearing bush.
4. A fluid dynamic bearing system according to claim 2, characterized in that the elastic element (4) is given the form of an elastic mounting between the bearing bush (2) and the sleeve (3).
5. A fluid dynamic bearing system according to claim 1, characterized in that the bearing bush (102) is formed as a part of a spindle motor hub made of plastic.
6. A fluid dynamic bearing system according to claim 1, characterized in that an elastic element (115) is disposed at the outside circumference of the bearing bush (113) by means of which the bearing bush is held in a hub (114) of a spindle motors.
7. A fluid dynamic bearing system according to claim 1, characterized in that bearing patterns are formed in a bearing surface of the bearing bush (2; 102).