Method for manufacturing a semiconductor device

PURPOSE: A method for manufacturing a semiconductor device is provided to minimize loss of a field oxide layer, and to reduce contact resistance by etching an etch stop layer using isotropic etching when forming a contact hole in a region with EFH(Effective Fox Height). CONSTITUTION: A substrate(100) defined by a low-voltage region(A) and a high-voltage region(B) is prepared. A thin gate oxide layer(102a) and a thick gate oxide layer(102b) are formed on the low and high voltage region, respectively. Gate lines with a hard mask are formed. A plurality of trenches are formed in the substrate. Field oxide layer(110) are filled in the trenches. An etch barrier layer(112) and an isolating oxide layer(114) are formed on the resultant structure. Contact holes are formed on the low-voltage region by selectively etching the isolating oxide layer. The exposed etch barrier layer is etched to expose the substrate by isotropic etching. Metal plugs(118) are filled in the contact holes. 본 발명은 반도체 소자의 제조방법에 관한 것으로, EFH(Effective Fox Height) 단차가 존재하는 지역에 드레인 콘택을 위한 콘택홀 형성공정시, 등방성 식각 특성을 가지는 식각공정을 이용하여 필드 산화막 식각 방지용 질화막을 식각함으로써 이 부위에서의 필드 산화막의 손실을 최대한 방지하여 액티브 지역(active region)의 면적을 증대시키는 것이 가능하며, 이에 따라, 이 부위에서의 콘택저항을 감소시킬 수 있는 반도체 소자의 제조방법을 제공한다.