KR20050094115A - Method for detecting a fine defect of semiconductor device - Google Patents

Abstract

 The present invention relates to a method for detecting a micro defect in a semiconductor device, and detects a leakage current that causes a micro defect to detect a micro defect that cannot be detected by a conventional wafer inspection equipment, and determines the existence by observing voltage contrast due to the micro defect. It is an object of the present invention to provide a method for shortening device development and ramp-up time by checking whether or not fine defects are generated during the process.

Description

METHOOD FOR DETECTING A FINE DEFECT OF SEMICONDUCTOR DEVICE

The present invention relates to a method for detecting a fine defect of a semiconductor device, by using the SEM equipment to observe the voltage contrast of the leakage current to determine the presence of fine defects during the process in the fab line, and shorten the device development and ramp-up time The present invention relates to a method for detecting a fine defect of a semiconductor device.

In general, in the method for detecting a micro defect of a semiconductor device according to the related art, a probe test is performed after the semiconductor device is processed, and a malfunction analysis and cause of the semiconductor device are identified. Then, the process of solving the malfunction caused by the micro-defect of the semiconductor device and performing the whole process again. Finally, after the probe test, a step of confirming that the malfunction of the microscopic defects is checked is performed.

1 is a cross-sectional view of a semiconductor device in which microdefects have occurred.

Referring to FIG. 1, it can be seen that a fine defect 60 is generated around the gate electrode 30 of the semiconductor device. These fine defects generate a short between the gate electrode 30 and the contact plug 50, and the short circuit causes a leakage current to cause a malfunction of the device.

2A to 2C are photographs showing a portion where microdefects of the above-described semiconductor element have occurred.

FIG. 2A is a photograph showing that a micro defect 60 in a stringer form is connected between gate electrodes of a semiconductor device. 2B is a photograph showing a tail-shaped fine defect 70 protruding from the lower portion of the gate electrode toward the contact plug. Figure 2c is a photograph showing the micro-defect 80 in the form of a semi-circular mott residue from the bottom of the gate electrode toward the contact plug.

The minute defects on the side of the gate electrode as shown in FIGS. 2A to 2C have a size of 50 nm or less, which is difficult to detect with a conventional wafer inspection apparatus capable of detecting only a minute defect of 100 nm or more. In addition, since the process of identifying and solving the cause of the micro-defect is performed after 4 months or more to confirm the result, there is a problem that it takes a considerable time to develop and ramp up the semiconductor device.

In developing and producing highly integrated semiconductor devices, resolving malfunctions of semiconductor devices due to microscopic defects has been the most important task in shortening development period and ramp-up.

The present invention, in order to solve the time-consuming problem of the micro-defect detection process in the prior art, to determine the presence of the micro-defect during the process in the fab line, the micro-defect of the semiconductor device that can shorten the device development and ramp-up time It is an object to provide a detection method.

The method for detecting fine defects in a semiconductor device according to the present invention comprises the steps of forming a polysilicon gate electrode and a contact plug on the semiconductor substrate;

Irradiating electrons to the semiconductor substrate to emit secondary electrons from the semiconductor substrate;

Observing the voltage contrast of the leakage current generated by electrons moving from the gate electrode to the contact plug using an SEM device

Characterized in that it comprises a.

In forming the contact plug, an ion implantation process is performed to form a source / drain region on the semiconductor substrate before the metal coating used to form the contact plug, and the contact plug uses one selected from aluminum, tungsten, and copper. do.

Hereinafter, with reference to the accompanying drawings and photos of the embodiment of the present invention will be described in detail.

3A to 3C are SEM photographs taken using a method for detecting a micro defect of a semiconductor device according to the present invention.

A gate electrode is formed on a semiconductor substrate, and a gate spacer is formed on sidewalls of the gate electrode. Next, an ion implantation process is performed to form source / drain regions, and the contact plug is formed using one selected from aluminum, tungsten and copper. Next, when electrons are irradiated onto the wafer in the process of observing the micro defect generation portion by the SEM, secondary electrons are generated on the wafer, and the secondary electrons are detected by the detector of the SEM. At this time, electron irradiation conditions should be set so that secondary electrons are emitted from the wafer.

3A is a top view of the top portion of the process of observing voltage contrast 90 under the conditions described above.

3B is a photograph showing a partial voltage contrast observation process in which a micro defect occurs. Compared with the planar photograph of the top portion, the portion that appears brighter than the other portion due to the generation of the voltage contrast 90 is the portion where the fine defect is generated.

FIG. 3C is a photograph showing a result of checking a cross section of a portion in which a micro defect observed in FIG. 3B has occurred. It can be seen that a triangular white fine defect occurred on the side of the gate electrode.

4A and 4B are equivalent circuits of a semiconductor device in which fine defect detection does not occur and the generated device, respectively.

FIG. 4A is an equivalent circuit showing a normal portion in which microscopic defects do not occur, as shown in FIG. 3A. Since the gate and the LPP are normally insulated, leakage current does not occur, and voltage contrast does not occur even under conditions in which secondary electrons diverge. It is a circuit that represents.

FIG. 4B is an equivalent circuit showing a portion where fine defects occur, as shown in FIG. 3B. The gate and the LPP come into contact with each other, whereby electrons move from the gate poly to the LPP, and a leakage current is generated. Defects can be observed.

5A to 5B are FIB photographs taken using a method for detecting a micro defect of a semiconductor device according to the present invention.

5A is a photograph of a state in which micro-defects are observed by FIB. As in the method of observing with the SEM, a voltage contrast 90 is generated in the micro-defect generation part by leakage current.

5B is a cross-sectional photograph of a portion where the voltage contrast 90 of FIG. 5A is generated. It can be seen that fine defects occurred on the side of the gate electrode in the same manner as the photograph taken by the SEM.

In the method for detecting a fine defect of a semiconductor device according to the present invention, the occurrence of fine defects is determined by observing the voltage contrast due to leakage current which causes the micro defects to detect the micro defects that cannot be detected by conventional wafer inspection equipment. Whether or not it can be checked during the process can reduce the device development and ramp-up time.

1 is a cross-sectional view of a semiconductor device in which microdefects have occurred.

2A to 2C are photographs showing a portion where microdefects occur in a semiconductor device according to the prior art.

3A to 3C are SEM photographs taken using a method for detecting microscopic defects of a semiconductor device according to the present invention.

4A to 4B are equivalent circuits of a semiconductor device and a device in which microdefects of the semiconductor device according to the present invention do not occur.

5A to 5B are FIB photographs taken using a method for detecting a micro defect in a semiconductor device according to the present invention.

<Description of Signs of Major Parts of Drawings>

10: semiconductor substrate 20: source / drain region

30 gate electrode 40 gate spacer

50: contact plug 60, 70, 80: fine defect

90: voltage contrast generation portion

Claims (5)

Forming a polysilicon gate electrode and a contact plug on the semiconductor substrate; Irradiating electrons onto the semiconductor substrate to emit secondary electrons from the semiconductor substrate; And Observing voltage contrast with leakage current generated by electrons moving from the gate electrode to the contact plug using SEM equipment Micro-defect detection method of a semiconductor device comprising a. The method of claim 1, The contact plug is a fine defect detection method of a semiconductor device, characterized in that using one selected from aluminum, tungsten and copper. The method of claim 1, And detecting the polysilicon deposition temperature above a polysilicon crystallization threshold temperature. The method of claim 1, And an ion implantation process for forming source / drain regions on the semiconductor substrate prior to the metal coating used to form the contact plugs when forming the contact plugs. The method of claim 1, Method for detecting a fine defect of a semiconductor device, characterized in that the FIB equipment can be used to observe the leakage current.