JPH04279042A - Etching residual inspection method - Google Patents

Abstract

PURPOSE:To enable the number of generated etching fine residuals in cylindrical shape which are formed on a substrate to be measured and inspected accurately by forming a side-wall portion corresponding to the etching residual being in contact with the etching residual and then measuring the number of side-wall portions by an optical means. CONSTITUTION:An SiO2 film 6 is formed on an Si substrate 1 where a cylindrical etching fine residual 5 is formed by a CVD device etc. After that, the SiO2 film 6 is etched back by dry etching for elimination. In this case, a side-wall spacer 6a according to SiO2 is formed in semi-spherical shape at the residual portion where the cylindrical etching fine residual 5 exists. After forming the SiO2 side-wall spacer 6a at a peripheral portion of the residual, the number of etching residuals which are formed on the Si substrate can be measured accurately by measuring the number of fine particles on a surface of the Si substrate 1 by a laser particle counter.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring and inspecting minute columnar etching residues, and more particularly to a method for quantitatively inspecting minute columnar etching residues generated during dry etching in the manufacture of semiconductor devices such as LSIs.

0002

2. Description of the Related Art With the increase in the degree of integration of semiconductor devices such as LSIs, advances in microfabrication techniques such as etching techniques have been remarkable in recent years. However, despite the rapid progress in microfabrication technology,
In particular, the problem of etching residue generated during dry etching is known.

[0003] First, single crystal silicon (Si)
During trench etching, residues (black silicon) are generated due to natural oxide film caused by the atmosphere in the chamber, etc. Second, residues (black silicon) are generated due to local etch rate differences due to Si segregation in Al-Si during Al etching. Si
A caused by residue and thirdly non-volatile substances such as Cu.
The fourth problem is the problem of the residue during l-Si-Cu etching, and the fourth problem is the needle-like residue caused by the natural oxide film mask as in the case of the single crystal trench etching. These etching residues are large enough to be observed with an optical microscope, so capacity evaluation is relatively easy, and measures to suppress them have now been established.

0004

[Problem to be Solved by the Invention] Residues other than those mentioned above, such as tungsten (W) polycide, that is, WSix/
For example, columnar etching residues that are assumed to be generated during dry etching of n+poly-Si include those with a diameter of 0.2 μm or less, so quantitative inspection of the number of generated residues can be performed using known optical means. There was a detection limit. FIG. 2 shows a process diagram of the formation of columnar etching minute residues. That is, as shown in FIG. 2(a), S
i-substrate 1, SiO2 film 2, n+polySi layer 3, Ws
If a deposit 7 such as a carbon-based polymer is deposited on the wafer on which the ix layer 4 is sequentially formed, the deposit slows down the etching rate of the material to be etched under the deposit, and as shown in FIG. After the intermediate etching process shown in FIG. 2(b), a small columnar etching residue shown at 5 in FIG. 2(c) remains.

An object of the present invention is to accurately measure and inspect the number of columnar etching minute residues formed on a substrate.

[0006]

[Means for Solving the Problems] According to the present invention, the above-mentioned problem is solved in a method for quantitatively inspecting columnar etching residues generated when a material to be etched is subjected to anisotropic etching. The problem is solved by an etching residue inspection method characterized in that the etching residue is quantitatively measured by forming sidewall parts corresponding to the number of etching residues and then measuring the number of sidewall parts by optical means.

The materials to be etched used in the present invention include polycide compounds of high-melting point metals such as titanium (Ti), tungsten (W), and molybdenum (Mo), as well as all materials that generate residues by the above-mentioned mechanism, such as polySi. Applicable to In addition, methods for forming sidewalls in contact with the etching residue include a residual formation method such as etchback, an adhesion formation method in which a part of the etching residue material is selectively grown, and a method for forming the sidewall portion in contact with the etching residue material. Alteration formation method that alters a part (for example, changing Si to S
iO2) etc. are preferably used. Note that it is preferable that the side wall material has an optical property that diffusely reflects light.

[0008] As the optical means used in the present invention, a particle counter, SEM, optical microscope, etc. are preferable.

[0009]

[Operation] According to the present invention, columnar etching residues having a minute horizontal cross section can be expanded in the horizontal direction and placed within the inspection resolution range of optical means, so the number of residues can be measured with high accuracy. It becomes possible to do so.

0010

Embodiments Hereinafter, embodiments of the present invention will be explained based on the drawings. FIG. 1 is a process sectional view for explaining an embodiment of the method according to the present invention.

In FIG. 1(a), for example, a width (diameter) W1 of about 0 is formed on a SiO2 film 2 formed on a Si substrate 1.
．． 2 μm circular columnar etching minute residue 5 (n+p
(consisting of an olySi layer 3 and a WSix layer 4) is formed.

Next, as shown in FIG. 1B, a SiO2 film 6 is formed on the Si substrate 1 on which the columnar etching minute residue 5 has been formed using a CVD (chemical vapor deposition) device or the like. Si
The thickness of the O2 film 6 was greater than the height of the columnar etching minute residue 5, and was, for example, 0.25 μm. Therefore, the SiO2 film 6 with a thickness of about 0.25 μm is also formed on the columnar etching minute residue 5. After that, Si was etched by dry etching.
The O2 film 6 is removed by etching back. At this time, where the columnar etching minute residue 5 exists,
A side wall spacer 6a made of SiO2 is formed in the residual portion in a hemispherical shape as shown in FIG. 1(c). The diameter W2 of this hemispherical sidewall spacer 6a is about twice the height of the columnar etching minute residue 5, that is, about 0.4
μm, and when the viewpoint is placed directly above the residue, the size of the residue becomes enlarged by SiO2 (that is, falls within the conventional measurement range). After forming the SiO2 sidewall spacer 6a around the residue, by measuring the number of microparticles on the surface of the Si substrate 1 using a laser particle counter, it is possible to accurately measure the number of etching residues formed on the Si substrate. .

Note that in the dry etching used in this example, C2Cl3F3-based and HBr-based gases were used.

[0014]

As described above, according to the present invention, it is possible to accurately measure and inspect the number of columnar etching minute residues generated when anisotropic dry etching is performed on a material to be etched.

[Brief explanation of the drawing]

FIG. 1 is a process sectional view for explaining an embodiment of the method according to the present invention.

FIG. 2 is a process cross-sectional view showing the process of forming columnar etching minute residues.

[Explanation of symbols]

1 Si substrate 2,6 SiO2 film 3 n+polySi layer 4 WSix layer 5 Column-shaped etching minute residue 6a Side wall spacer 7 Adherence

Claims (1)

[Claims] 1. In a method for quantitatively inspecting columnar etching residues generated when anisotropic etching is performed on a material to be etched, after forming sidewall portions corresponding to the number of etching residues in contact with the etching residues, An etching residue inspection method characterized in that the etching residue is quantitatively measured by measuring the number of the sidewall portions by optical means.