KR20050073282A - Method for detecting defects of semiconductor devices - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting a defect in a semiconductor device, and after the formation of a gate spacer, cleaning of residual polysilicon on an active region connected to the gate polysilicon also removes the gate polysilicon under the gate electrode and then scans a scanning electron microscope. By detecting the defect of the device by using the difference in brightness of light on), it is possible to prevent unnecessary subsequent processes to improve the process yield and the reliability of the device.

Description

Fault detection method of semiconductor device {METHOD FOR DETECTING DEFECTS OF SEMICONDUCTOR DEVICES}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting defects in semiconductor devices. In particular, SEM (scanning electron) is removed after removing the gate polysilicon under the gate electrode by cleaning residual polysilicon on the active region connected to the gate polysilicon after the formation of the gate spacer. The present invention relates to a method for detecting a defect of a semiconductor device, by detecting a defect of a device by using a difference in brightness of light on a microscope, thereby preventing unnecessary subsequent processes, thereby improving process yield and reliability of the device.

As the pattern becomes finer in the semiconductor device manufacturing process, minimizing the effect on defects has become a key factor in securing process yield. Observation of defects on patterned wafers is indispensable for follow-up and countermeasures in the event of process failures, so finding more defects can lead to process causes, measures and countermeasures, resulting in faster process stabilization and improved process yield. There is an advantage.

The defect caused by the residual polysilicon causes the semiconductor device to be electrically damaged due to the residual polysilicon remaining in the moat, causing bridges between gates, bridges between gates and landing plug contacts, and bridges between gates and bitline contacts. It is causing serious damage to its operation.

1 is a cross-sectional SEM photograph of a semiconductor device.

Referring to FIG. 1, it can be seen that a residue of polysilicon connected to the gate polysilicon pattern is in the active region. This means that there is a defect in the device.

2 is a planar SEM photograph of the semiconductor device.

Referring to FIG. 2, the photograph of the left side shows that the polysilicon residue is formed, and the photograph of the right side shows that the polysilicon residue is not formed and thus the semiconductor device is free of defects.

However, a defect such as a residue on the active region of the gate polysilicon is not classified as a scanning electron microscope (SEM), which is a conventional defect detection device, and thus there is a problem that defects cannot be detected.

The present invention is to solve the above problems, an object of the present invention after removing the gate polysilicon under the gate electrode by cleaning the residual polysilicon on the active region connected to the gate polysilicon after the gate spacer is formed The present invention provides a method for detecting a defect in a semiconductor device that can detect a defect of a device by using a difference in brightness of light on a scanning electron microscope, thereby improving process yield and device reliability by preventing unnecessary subsequent processes. .

The present invention is to achieve the above object, the characteristics of the defect detection method of a semiconductor device according to the present invention,

In the defect detection method of a semiconductor element,

Forming a gate electrode formed of a laminated structure of polysilicon, tungsten nitride and a hard mask on a semiconductor substrate;

Depositing a nitride film on the entire surface of the structure;

Forming a spacer by performing an entire surface etching process on the structure;

Cleaning the polysilicon residue between the gate electrodes;

The present invention provides a process for detecting defects by observing contrast differences of SEM pictures of the above structure.

In addition, another feature of the present invention, the cleaning step is characterized in that using NH4OH.

3A and 3B show a defect detection process diagram of a semiconductor device according to the present invention.

Referring to FIG. 3A, a gate electrode 18 having a stacked structure of polysilicon 12, tungsten nitride 14, and hard mask 16 is formed on semiconductor substrate 10.

Thereafter, a nitride film (not shown) is deposited on the entire surface of the structure, and then the gate spacer 20 is formed by performing a front etching process on the structure. At this time, the remaining polysilicon connected to the polysilicon 12 for the gate electrode is placed on the active region of the semiconductor substrate 10.

Referring to FIG. 3B, the polysilicon residue between the gate electrodes 18 is cleaned. Here, it is preferable to use NH4OH for the washing step.

The washing with NH4OH does not affect word lines without generation of residual polysilicon, but in the wordline with residual polysilicon, residual polysilicon is etched and even polysilicon in the gate electrode is etched under the gate electrode. Create an empty space.

The defects are then detected by observing the contrast differences in the SEM pictures of the structure.

4 is a planar SEM photograph of semiconductor device defects detected in accordance with the present invention. Here, the bright word line and the dark word line can be observed on the SEM image, where the dark word line represents an empty space under the gate electrode. As a result, it can be seen that the word line has a defect.

As described above, in the defect detection method of the semiconductor device according to the present invention, after removing the gate polysilicon under the gate electrode by cleaning the residual polysilicon on the active region connected to the gate polysilicon after the gate spacer is formed. By detecting the defect of the device by using the difference in brightness of the light on the scanning electron microscope (SEM), it is possible to prevent unnecessary subsequent processes to improve the process yield and the reliability of the device.

1 is a cross-sectional SEM photograph of a semiconductor device.

2 is a planar SEM photograph of a semiconductor device.

3A and 3B are defect detection process diagrams of a semiconductor device according to the present invention.

4 is a planar SEM photograph of a semiconductor device defect detected in accordance with the present invention.

<Description of the reference numerals for the main parts of the drawings>

10 semiconductor substrate 12 polysilicon

14 tungsten silicide 16: hard mask

18 gate electrode 20 gate spacer

Claims (2)

Forming a gate electrode formed of a laminated structure of polysilicon, tungsten nitride and a hard mask on a semiconductor substrate; Depositing a nitride film on the entire surface of the structure; Forming a spacer by performing an entire surface etching process on the structure; Cleaning the polysilicon residue between the gate electrodes; A defect detection method of a semiconductor device, comprising the step of detecting a defect by observing the contrast difference of the SEM photograph of the structure. The method of claim 1, The cleaning process is a defect detection method of a semiconductor device, characterized in that using NH4OH.