JPS63228014A - Solid-state shape evaluating device - Google Patents

Abstract

PURPOSE:To evaluate the shape of a round shape formed in a sample and to evaluate the solid shape of the sample without destroying it by inputting an image of the state of the slanted sample and approximating the round hole to an ellipse. CONSTITUTION:A semiconductor wafer S where a contact hole H is formed is placed on a sample base 1, which is slanted by a tilt angle theta,; and the angle thetais stored in a numeral memory part 2 and an image input part 3 inputs the image of the slanted wafer S and stores it in an image memory art 4. In general, a scanning electron microscope is used as the input part 3, but an image obtained by it has a high noise level, so the contour of the hole H is detected only partially. For the purpose, the image stored in the memory part 4 is processed by an image processing part 5 to obtain the edge of the hole H, from which the expression of the ellipse is estimated; and an arithmetic part 6 calculates the depth of the hole H and the diameter of its reverse surface from the position of the edge and the angle theta.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a three-dimensional shape evaluation device for evaluating the shape of, for example, a contact hole in a semiconductor wafer.

[Conventional technology]

Fig. 2 is a cross-sectional view showing a contact hole χ of a semiconductor wafer for evaluating a conventional three-dimensional shape. , and a nine-figure contact hole H having a depth D is provided.

Next, evaluation of the three-dimensional shape, that is, the contact hole H, will be explained.

First, when evaluating the contact hole H1' of the semiconductor wafer S, the semiconductor wafer Sft is opened and the contour hole A is
By observing the cross section of /H, the diameter d0. Measure d, # and depth DY.

The aforementioned three-dimensional shape evaluation method is described, for example, on page 119 of Semiconductor Lingraphy Technology (Hiroichi Otori, published by Sangyo Tosho on July 30, 1980).

[Problem that the invention seeks to solve]

Since the conventional three-dimensional shape evaluation is performed as described above, there is a problem in that the semiconductor substrate S must be destroyed in order to evaluate the three-dimensional shape.

Does this invention have the above problems? This was done to solve the problem, and is it possible to obtain a three-dimensional shape evaluation device that can evaluate the sample without destroying it? purpose.

[Means for solving problems]

The three-dimensional shape evaluation device according to the present invention evaluates the shape χ of a round hole by inputting an image χ of a tilted sample and approximating the round hole formed in the sample to an ellipse. be.

[Effect]

The three-dimensional shape evaluation device according to the present invention calculates data (evaluation parameters) Y of a round hole based on the shape approximated to an ellipse.

〔Example〕

Hereinafter, one embodiment of the present invention shown in FIG. Y will be described.

In FIG. 1, 1 indicates a sample stage, on which a semiconductor wafer S as a sample is placed. And semiconductor wafer S&L
A contact hole H (see FIG. 2) is formed as a round hole.

2 & Numerical memory section for storing the inclination angle θY of the specimen stage 1, 6
Is this an image of semiconductor wafer S? 4 is an image memory section for storing image input from the image input section 6;
6 is an image processing unit that performs processing χ on the input image of the image memory unit 40 to detect contact holes HY, and 6 is an arithmetic unit ? data (evaluation parameter) of the contact hole H from the inclination angle θ from the numerical memory section 2 and the output of the image processing section 5?
calculate.

Reference numeral 7 indicates a display unit that displays the data obtained by the calculation unit 6.

Next, the operation will be explained.

First, the semiconductor wafer St in which the contact hole H is formed is placed on the sample stage 1, the sample stage 1χ is tilted at an inclination angle θ, and the inclination angle θY is stored in the numerical memory section 2. At the same time, the semiconductor wafer S is A tilted image RY is input and stored in the image memory s4.

When inputting an image from the image input unit 6 in this way, if the cross-sectional shape of the contact hole H is the cross-sectional shape shown in FIG. Become.

Generally, one diameter d4), d, &'! of a contact hole H in a highly integrated semiconductor wafer S is d4), d, &'! , on the order of submicrons, and a scanning electron microscope is used as the image input unit 6 from the viewpoint of resolution.

The image taken by this scanning electron microscope was processed, but since the image was noisy, the outline of the contact hole H shown in @3 causes (
Solid line *) Since tX can only be detected partially, the image stored in the image memo IJ m4 is processed by the image processing unit 5. An ellipse equation χ is estimated from the obtained edge of the contact hole H, and the Depth D-? Calculate the diameter of the lower surface doya.

The procedure for calculating the data mentioned above will be explained below. First, if we take the coordinate system as shown in Figure 3, the equations for the upper and lower ellipses are: 2a Major axis of the upper ellipse 2b Shorter axis of the upper ellipse Diameter YoG! Y coordinate of the center of the ellipse on the lower surface k &X is the ratio of the lower surface diameter to the upper surface diameter.

Furthermore, when the inclination angle θ is used, the relationship between a and b becomes the following relationship.

b==a θ ・・・・・・・・・
...(3) The values of g, a, and b can be obtained by measurement from an edge image subjected to image processing χ.

Next, for example, two points A (Xl, Y,) and B (Yt,
Yt) was extracted from the two equations and substituted into equation (2).'! Atk becomes .

Therefore, the aforementioned y. , the diameter d6 from k to the bottom surface - and the depth D is do=kd1=2ka...
・・・・・・・・・・・・ (6) D = I yo I
/a sum θ ・・・・・・・・・・・・
... It can be obtained as (7).

The above calculations are performed by the calculation section 6, and the results are displayed on the output section 7.

What? In the above embodiment, the measurement of the contact hole H of the semiconductor block /S3 was explained, but it goes without saying that other contact holes may be used as long as they have a similar round hole shape.

Furthermore, edge detection was difficult because a scanning electron microscope was used as the image input section 6, but data can be calculated with high accuracy if a device that can clearly obtain images is used.

〔Effect of the invention〕

As described above, according to the present invention, data for evaluating the shape of a round hole can be obtained from a single image of a sample, which simplifies the configuration and allows for non-destructive sample preparation.
It has the excellent effect of allowing non-contact evaluation.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing a three-dimensional shape evaluation apparatus according to an embodiment of the present invention, FIG. 2 is a sectional view showing a contact hole for a semiconductor probe, and FIG. 3 is an explanatory diagram showing an image captured by an image input section. . In the figure, 1 is a sample stage, 2 is a numerical memory section, 3 is an image input section, 4 is an image memory section, 5 is an image processing section, 6 is a calculation section, S is a semiconductor wafer, and H is a contact hole χ 8. In the figures, the same reference numerals indicate the same or corresponding parts. Fig. 1 Fig. 1: Sample analysis 3: Image input @p S: Flat conductor wafer Fig. 2 Fig. 3

Claims (1)

[Claims] A sample stage on which a sample with a round hole is placed, a number memory unit that stores the tilt angle of this sample stage, and an image input unit that inputs an inclined image of the sample placed on the sample stage. an image memory section that stores an input image from the image input section; an image processing section that performs image processing on the input image stored in the image memory section to detect edges of the round hole;
A three-dimensional shape evaluation device comprising: a calculation unit that calculates data regarding the round hole based on the position of the edge of the round hole and the inclination angle stored in the numerical memory unit.