Image sensor and method for manufacturing the same

Abstract

An image sensor and a method for manufacturing the same are provided. In the method, a photoresist is formed on a substrate including a photodiode region and a gate electrode opposite to the photodiode region on the basis of the gate electrode. An oxide layer is formed to a specific thickness on both the photodiode region and a part of the gate electrode. The photoresist is removed from the substrate and cleaned. A first oxide film is formed on the substrate, the gate electrode, and the oxide layer remaining on the photodiode region. A nitride film is formed on the first oxide film. And a second oxide film is formed on the nitride film. Blank etching is performed on the first oxide film, the nitride film, and the second oxide film to form a spacer at the side of the gate electrode.

1 . A method for manufacturing an image sensor, the method comprising: 
 forming a photoresist on a substrate including a photodiode region and a gate electrode opposite to the photodiode region;    forming an oxide layer on both the photodiode region and a part of the gate electrode;    removing the photoresist from the substrate and cleaning the substrate;    forming a first oxide film on the substrate, the gate electrode, and the oxide layer remaining on the photodiode region;    forming a nitride film on the first oxide film;    forming a second oxide film on the nitride film; and    performing blank etching on the first oxide film, the nitride film, and the second oxide film to form a spacer at the side of the gate electrode.    
   
   
       2 . The method according to  claim 1 , further comprising forming a Pre-Metal Dielectric (PMD) layer on both the oxide layer remaining on the photodiode region and the spacer formed at the side of the gate electrode.  
   
   
       3 . The method according to  claim 2 , wherein the PMD layer is formed by depositing and annealing a material selected from borosilicate glass (BSG), phosphosilicate glass (PSG), borophosphosilicate glass (BPSG), and undoped silicate glass (USG) and then flattening a surface of the PMD layer through a Chemical Mechanical Polishing (CMP) process.  
   
   
       4 . The method according to  claim 1 , wherein the oxide layer includes a SiO 2  layer that is formed having a thickness of 3000-3500 Å by depositing SiO 2  in a low temperature atmosphere with silane gas in a Chemical Vapor Deposition (CVD) chamber and then performing a CMP process.  
   
   
       5 . The method according to  claim 1 , wherein the blank etching is performed using a Reactive Ion Etching (RIE) method so that a portion of the oxide layer remains.  
   
   
       6 . The method according to  claim 2 , wherein the PMD layer is formed using the same material as that of the oxide layer.  
   
   
       7 . An image sensor comprising: 
 a substrate including a photodiode region formed therein;    a gate electrode formed on the substrate, the gate electrode being in contact with the photodiode region;    an oxide layer formed on the photodiode region; and    a spacer provided at one side of the gate electrode opposite to the oxide layer.    
   
   
       8 . The image sensor according to  claim 7 , further comprising a Pre-Metal Dielectric (PMD) layer that covers the spacer and the substrate.  
   
   
       9 . The image sensor according to  claim 7 , wherein the oxide layer includes SiO 2  and has a thickness of 3000-3500 Å.  
   
   
       10 . The image sensor according to  claim 7 , wherein the spacer has a multilayer structure including a first oxide film, a nitride film, and a second oxide film that are sequentially layered on both the substrate and one side surface of the gate electrode.  
   
   
       11 . The image sensor according to  claim 8 , wherein the PMD layer and the oxide layer are formed of SiO 2 .