Method for forming isolation layer in semiconductor device

Abstract

A method for forming an isolation layer in a semiconductor device includes forming a trench in a semiconductor substrate. A liner layer that includes a liner nitride layer and a liner oxide layer is formed on an exposed surface of the trench. A flowable insulation layer is formed to fill the trench. The flowable insulation layer is recessed to expose a portion of the liner nitride layer on an upper portion of the trench. A first preheating process is performed to release stress of the liner layer. A second preheating process is performed to oxidize the exposed liner nitride layer. A buffer layer is formed on a portion of the liner layer that is formed on a sidewall of the trench and exposed after the flowable insulation layer is recessed. The buffer layer is etched to smoothen a rough portion of the liner layer that is formed when the flowable insulation layer is recessed. A buried insulation layer is deposited in the trench.

1 .- 13 . (canceled) 
     
     
         14 . A method for forming an isolation structure in a semiconductor device, the method comprising:
 forming a trench in a semiconductor substrate;   forming a liner layer on an exposed surface of the trench, the liner layer comprising a liner nitride layer and a liner oxide layer;   forming a flowable insulation layer to fill the trench and cover the liner nitride layer;   recessing the flowable insulation layer to expose a portion of the liner nitride layer on an upper portion of the trench;   loading the semiconductor substrate into a chamber after the recessing step;   performing a first preheating process by supplying a first preheating gas to the chamber so as to release stress of the liner layer;   performing a second preheating process by supplying a second preheating gas to the chamber so as to oxidize the exposed liner nitride layer;   forming a buffer layer on the exposed liner nitride layer;   etching the buffer layer by supplying an etch gas to the buffer layer so as to smoothen the exposed liner nitride layer; and   depositing a buried insulation layer in the trench to foam an isolation structure.   
     
     
         15 . The method of  claim 14 , wherein the first preheating gas comprises argon (Ar) and helium (He) gases, and the second preheating gas comprises oxygen (O 2 ), argon (Ar), and helium (He) gases. 
     
     
         16 . The method of  claim 14 , wherein the recessing of the flowable insulation layer is performed using a wet etch chemical comprising a hydrofluoric acid (HF), wherein the flowable insulation layer is recessed about 1100 Å to about 1400 Å. 
     
     
         17 . The method of  claim 14 , wherein the performing of the first preheating process, the performing of the second preheating process, the forming of the buffer layer, the etching of the buffer layer, and the depositing of the buried insulation layer are performed using an HDP process. 
     
     
         18 . The method of  claim 14 , wherein the first and second preheating processes are complete within sixty seconds. 
     
     
         19 . The method of  claim 14 , wherein the forming of the buffer layer comprises:
 forming a first buffer layer on the portion of the liner layer to a predetermined thickness for preventing generation of a void in the sidewall of the trench by supplying oxygen (O 2 ), silane (SiH 4 ), and helium (He) gases to the trench; and   forming a second buffer layer as a seed layer for the buried insulation layer by supplying oxygen (O 2 ), silane (SiH 4 ), hydrogen (H 2 ), and helium (He) gases to the first buffer layer.   
     
     
         20 . The method of  claim 19 , wherein each of the first and second buffer layers has a thickness of about 250 Å to about 350 Å. 
     
     
         21 . The method of  claim 14 , wherein the etching of the buffer layer is performed such that the liner nitride layer remains on the exposed surface of the trench. 
     
     
         22 . The method of  claim 14 , wherein the depositing of the buried insulation layer comprises:
 after the etching of the buffer layer, forming an HDP oxide layer on the buffer layer by supplying an HDP deposition source to the semiconductor substrate;   etching away an overhang of the HDP oxide layer formed at an upper portion of the trench; and   repeating the forming of the HDP oxide layer and the etching of the overhang to form the buried insulation layer.   
     
     
         23 . The method of  claim 22 , wherein the forming of the HDP oxide layer and the etching of the overhang are repeated three, four, or five times. 
     
     
         24 . The method of  claim 22 , wherein the HDP deposition source comprises oxygen (O 2 ), silane (SiH 4 ), hydrogen (H 2 ), and helium (He) gases.