KR20030041602A - Preparation of FIB-TEM sample using SOG in Semiconductor wafer - Google Patents

Abstract

PURPOSE: A method for manufacturing an FIB(Focused ion beam)-TEM(Transmission Electron Microscope) sample of a semiconductor wafer using SOG(Spin On Glass) is provided to be capable of preventing the damage of the uppermost layer of the semiconductor wafer due to an FIB process. CONSTITUTION: The first marking portion is formed on a silicon wafer(20) by using the first marking process for indicating a predetermined portion(21). After forming an SOG layer(23) on the resultant structure, the second marking portion(24) is formed in the SOG layer(23) by using the second marking process. A sample is formed by cutting the resultant structure with a dicing saw using the second marking portion(24) as a reference. The sample is then attached on a copper grid. A milling process is carried out on the sample by FIB using the predetermined portion(21) as a reference. At this time, the uppermost portion of the sample is protected by the SOG layer(23).

Description

Fabrication method of FIV-TEM specimens using SOX on semiconductor wafers {Preparation of FIB-TEM sample using SOG in Semiconductor wafer}

The present invention is a TEM specimen manufacturing method that can accurately analyze the defect of a specific region by using the FIB on the wafer, the SOG is applied to the surface of the region to be analyzed by applying SOG before FIB (focused ion beam) processing Fabrication of FIB-TEM specimens using SOG on semiconductor wafers that can be analyzed without damage to the area to be analyzed during TEM analysis such as new product development of semiconductor devices and defect analysis of mass-produced products. It is about a method.

In order to observe a specific part on the wafer during the semiconductor manufacturing process, first, sample the specific part of the wafer to form a sample, and then confirm the test piece with an analysis device to determine the structure of the specific area or the surface shape. Or component investigation.

As a conventional technique for fabricating TEM specimens for such an analysis, a focused ion beam (FIB) method has been proposed.

Figures 1a to 1d is a view showing a TEM specimen manufacturing process according to the prior art.

First, as shown in FIG. 1A, a specific portion 11 to be analyzed on the wafer is marked 12 using a focused ion beam (FIB) or a laser, and a dicing saw is formed as shown in FIG. 1B. Using the cut so that the marked area is in the center.

Subsequently, as shown in FIG. 1C, the specimen cut using dicing saw is fixed to the copper grid 13 cut in half using an adhesive or the like, and then the marking portion 12 is removed in the FIB as shown in FIG. 1D. After confirming, mill both sides around the part that you want to analyze about tens of micrometers in width so that the final thickness of the specimen is less than 1000 되면, and when the specimen is completed, transmit the electron beam through the specimen through TEM (Transmission Electron Microscope) Or analyze the components.

The conventional FIB-TEM specimen manufacturing method has a problem that cannot be analyzed because the surface is damaged in the process of observing the image in the FIB or marking, W coating, milling, etc. for the portion to be analyzed.

The present invention was created to solve the above problems, and an object of the present invention relates to a method for manufacturing a FIB-TEM specimen without damaging the uppermost layer by FIB when analyzing a specific region on a wafer. It is to provide a method for fabricating FIB-TEM specimens using SOG on semiconductor wafers to prevent damage caused by FIB beam on the part to be analyzed by applying SOG before FIB processing when analyzing specific areas such as defect analysis of development and mass production products. .

Figures 1a to 1d is a view showing a TEM specimen manufacturing process according to the prior art.

2a to 2f is a view showing a TEM specimen manufacturing process according to the present invention.

Figure 3 is a view showing a specimen produced by the present invention.

-Explanation of symbols for the main parts of the drawings-

10, 20: wafer 11, 21: analysis site

12: marking part 13: copper grid

22: first marking portion 23: SOG film

24: second marking site

The present invention for achieving the above object is a first marking process for marking a specific area to be observed on a silicon wafer, the step of applying and drying the SOG after the first marking process, and the optical after SOG application A second marking process for finding and marking a first marking portion or an area to be analyzed on a microscope, a cutting process for cutting with dicing saw after the second marking process, and fixing the specimen cut with the dicing saw to a copper grid And a milling process for milling in FIB centering on a specific region to be analyzed for the specimen fixed to the copper grid, to fabricate a FIB-TEM specimen using SOG in a semiconductor wafer. .

At this time, the thickness of the SOG film applied in the SOG coating process is thousands of ㎛ ~ 1㎛, the process of milling the specimen in the FIB centered on the specific region to analyze the specimen fixed to the copper grid thickness of the specimen less than 1000Å It is characterized by that.

In addition, the first and second marking process, characterized in that the marking using a laser.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings. In addition, the present embodiment is not intended to limit the scope of the present invention, but is presented by way of example only and the same parts as in the conventional configuration using the same reference numerals and names.

2a to 2f is a view showing a TEM specimen manufacturing process according to the present invention.

TEM specimen manufacturing method according to the present invention is made based on the TEM cross-section specimen manufacturing process of a specific area, and the SOG coating process, marking process, cutting process, attachment process and milling process can be made in sequence to produce a TEM analysis cross-section specimen Will be.

First, FIG. 2A is a cross-sectional view showing a first marking portion 22 by performing a first marking process on a portion to be analyzed with a laser on a specific region 21 to be analyzed on a silicon wafer 20. 2A (b) is a cross-sectional view of the first marking portion.

Subsequently, as shown in the cross-sectional view of (a) of FIG. 2b, the SOG 23 is applied and dried in the order of several thousands of micrometers to 1 µm, and then the specific portion 21 to be analyzed as shown in the top view of (a) of FIG. After SOG is applied, the position can be confirmed because light passes through the SOG in the optical microscope, but since FION uses the ION beam, the position cannot be identified. As shown in the cross-sectional view of (b), the second marking portion 24 is formed using a laser.

Subsequently, as illustrated in FIG. 2D, a cutting process of cutting a dicing saw based on the second marking portion 24 is performed, followed by dicing saw as illustrated in FIG. 2E. An attaching step for fixing the cut specimen to the copper grid 13 using an instant adhesive or the like is performed.

As shown in FIG. 2F, the FIB is milled so that the thickness of the final planar specimen is about 1000 mm or less with reference to the second marking portion 24 in the FIB.

Figure 3 is a TEM analysis of the specimen produced by the present invention can be seen that the gate is protected by SOG does not cause damage to the gate.

As described above, in the present invention, when fabricating a TEM specimen for analysis of a specific region on a wafer, SOG is applied before FIB processing so that damage of the FIB beam does not occur on the surface of the part to be analyzed, thereby developing a new semiconductor device. There is an advantage that accurate analysis can be done without damaging specific area analysis such as failure analysis of mass production products.

Claims (4)

A first marking process for marking a specific area to be observed on a silicon wafer; Applying and drying SOG after the first marking process; A second marking process of finding and marking a first marking portion or an area to be analyzed on an optical microscope after the SOG coating; A cutting step of cutting with dicing saw after the second marking step; An attachment step for fixing the specimen cut with the dicing saw to a copper grid; A milling process of milling in FIB centering on a specific region to be analyzed for specimens fixed to the copper grid, FIB-TEM specimen manufacturing method using SOG on a semiconductor wafer comprising a. The method of claim 1, wherein the SOG film applied in the SOG coating process has a thickness of several thousands μm to 1 μm. According to claim 1, wherein the process of milling the specimen in the FIB centered on a specific region to analyze the specimen fixed to the copper grid FIB- using a semiconductor wafer SOG, characterized in that the thickness of the specimen is less than 1000Å How to make TEM specimens. The method of fabricating a FIB-TEM specimen according to claim 1, wherein the semiconductor wafer is marked using a laser during the first and second marking processes.