Method of forming a shallow trench isolation structure in a semiconductor device
View Patent ↗An isolation method in a semiconductor device is disclosed. The example method sequentially forms a pad oxide layer and a pad nitride layer on a semiconductor substrate, patterns the pad nitride and oxide layers to form an opening exposing a portion of the substrate, and forms a trench in exposed portion of the substrate. The example method also etches the patterned pad nitride layer to extend the opening, carries out SAC oxidation on the extended opening and the trench to provide a rounded corner to an upper corner of the substrate in the vicinity of the trench, and fills the trench with an insulating layer.
1. An isolation method in a semiconductor device, comprising:
sequentially forming a pad oxide layer and a pad nitride layer on a substrate;
forming a mask on the pad nitride layer;
sequentially etching, by using the mask, the pad nitride and oxide layers to form an opening exposing a portion of the substrate;
forming a trench in the exposed portion of the substrate;
removing the mask from the pad nitride layer, wherein the pad nitride layer has rounded corners after removing the mask;
further selectively etching the etched pad nitride layer to extend the opening;
carrying out SAC oxidation on the extended opening and the trench to provide a rounded corner to an upper corner of the substrate in the vicinity of the trench; and
filling the trench with an insulating layer.
2. The isolation method of claim 1 , wherein further selectively etching the etched pad nitride layer is performed using a H 3 PO 4 solution at 100˜200° C.
3. The isolation method of claim 1 , wherein the opening is extended to a length of 200˜500 Å.
4. The isolation method of claim 1 , wherein a radius of the upper corner is adjustable by an extended length of the extended opening.
5. The isolation method of claim 1 , wherein the mask is removed from the pad nitride layer before further selectively etching the etched pad nitride layer.
6. The isolation method of claim 1 , wherein the mask is removed from the pad nitride layer after sequentially etching the pad nitride and oxide layers to form the opening exposing the portion of the substrate.
7. The isolation method of claim 1 , wherein the opening is extended by a length of 200-500 Å.
8. The isolation method of claim 1 , wherein a radius of the upper corner is determined by a distance by which the etched pad nitride layer is further selectively etched.
9. An isolation method in a semiconductor device, comprising:
sequentially forming a pad oxide layer and a pad nitride layer on a substrate;
forming a mask on the nad nitride layer;
sequentially etching, by using the mask, the pad nitride and oxide layers to form an opening exposing a portion of the substrate;
forming a trench in the exposed portion of the substrate;
removing the mask from the pad nitride layer;
further selectively etching the etched pad nitride layer to extend the opening, wherein after sequentially etching the pad nitride and oxide layers and before further selectively etching the etched pad nitride layer, the pad nitride layer has rounded corners;
carrying out SAC oxidation on the extended opening and the trench to provide a rounded corner to an upper corner of the substrate in the vicinity of the trench; and
filling the trench with an insulating layer.
10. The isolation method of claim 9 , wherein the pad nitride layer has rounded corners after removing the mask.