1. Field of the Invention
The invention relates generally to a transistor in a semiconductor device and a method of manufacturing the same, and more particularly to, a transistor in a semiconductor device and a method of manufacturing the same in which an oxygen ion implantation layer is formed below a LDD region.
2. Description of the Prior Art
Generally, as the integration level of semiconductor devices is higher, the size of a transistor is reduced. Also, as the size of the transistor is reduced, there occurs a problem that various electrical characteristics are degraded.
In order to solve this problem, the transistor is formed recently using a substrate having a SOI (silicon on insulator) structure in which a silicon layer is formed on an insulating film or a SIMOX (separation by implantation of oxygen) structure in which an oxygen layer is formed therein.
If this type of the substrate is used, however, the transistor maintains an electrically floating state with the substrate since it is formed over the insulating film or the oxygen layer. Due to this, a body effect by which the threshold voltage between a junction region and the substrate is changed, a King effect causing a punch through as holes are not discharged into the substrate but moved toward the junction region, and the like are generated to degrade reliability of the device.
In order to prevent this phenomenon, a contact hole through which the insulating film or the oxygen layer is penetrated is formed and a plug is formed therein, so that the transistor is not electrically floated. This method, however, requires additional complex process of forming the contact hole.
Also, as the integration level is higher, there is a problem that the junction leakage current is abruptly increased since silicide is penetrated deep into the substrate.
It is therefore an object of the present invention to provide a transistor in a semiconductor device and method of manufacturing the same, in which a bulk substrate made of a single crystal silicon is used but an insulating layer into which oxygen is injected is formed below a LDD region, thus obtaining the same effect such as using a substrate of a SOI structure or a SIMOX structure and preventing a lowering in an electrical characteristic and an increase in the junction leakage current depending on higher integration of a device.
In order to accomplish the above object, a transistor in a semiconductor device according to the present invention is characterized in that it comprises a semiconductor substrate in which a device isolation film of a trench structure is formed, a gate electrode formed on the semiconductor substrate in a channel region and electrically separated from the semiconductor substrate by a gate insulating film, and a junction region of a LDD structure in the semiconductor substrate on both sides of the gate electrode, wherein the transistor further comprising an insulating layer in which ions are injected below the LDD region in the junction region.
Also, a method of manufacturing a transistor in a semiconductor device according to the present invention is characterized in that it comprises the steps of injecting, by a given depth, ions into an active region in a semiconductor substrate in which a device isolation film is formed to form an insulating layer; forming a gate insulating film and a gate electrode on the semiconductor substrate in the channel region; forming a LDD region in the semiconductor substrate on the LDD region; forming an insulating film on the entire structure, forming an insulating film spatter on sidewalls of the gate electrode and performing an etch process so that the LDD region and the insulating layer are etched to form a groove at the side of the spacer; growing an epitaxial silicon layer in the groove and injecting impurity ions into the epitaxial silicon layer to form a junction region of a LDD structure; and forming a silicide layer on the surface of the gate electrode and the junction region.
The semiconductor substrate is a single crystal silicon substrate manufactured using Czochralski method, the ions is oxygen and the insulating layer is formed in thickness of 500xcx9c1000 xc3x85 from the surface of the semiconductor substrate.