JPH04290241A - Measuring-point selection apparatus for electron-beam tester use - Google Patents

Abstract

PURPOSE:To eliminate a need for the skill of an operator at a selection operation and to shorten the selection time by a method wherein a measuring point whose local field effect on a measuring interconnection is small is selected automatically. CONSTITUTION:At a measuring-point selection apparatus, an operator designates the net name of a measuring interconnection from a keyboard 10 to a computer 12. Then, the computer 12 reads out an interconnection design data corresponding to the designated net name from an external storage device 14, selects from the measuring interconnection a measuring point whose local field effect is small and feeds it to an electron-beam tester 16. A CAD data regarding the interconnection of a semiconductor integrated circuit as a measuring object is stored in the external storage device 14. The following are stored as the data: a net list 14a which expresses the logical connection relationship of the interconnection provided with a net name; a layout data 14c which expresses the shape and the arrangement of the interconnection; and a cross mapping 14b which corresponds to the net list 14a and the layout data 14c.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a measurement point selection device for an electron beam tester.

0002

[Prior Art] When measuring the voltage waveform applied to the internal wiring of a semiconductor integrated circuit using an electron beam tester, in order to improve the measurement accuracy, it is necessary to minimize the local electric field effect within the wiring to be measured. It is necessary to select a position and irradiate this position (measurement point) with an electron beam. This local electric field effect becomes more pronounced as the degree of integration of semiconductor integrated circuits increases, so in recent years as the degree of integration has increased, selection of measurement points using an electron beam tester has become important.

Conventionally, measurement points were selected in the following manner. In other words, the measurement wiring pattern is created using CAD data using an EWS (Engineering Workstation).
At the same time, an SEM image of the wiring to be measured was obtained using an electron beam tester and displayed on the screen. Then, the operator takes these two images into consideration and supplies measurement points to the electron beam tester directly or via the EWS.

0004

[Problems to be Solved by the Invention] However, in order to select a measurement point where the local electric field effect is small, operator skill is required and selection takes a long time.

SUMMARY OF THE INVENTION In view of these problems, an object of the present invention is to provide a measurement point selection device for an electron beam tester that can automatically select a measurement point with a small local field effect from the measurement wiring. .

[0006]

Means for Solving the Problems and Their Effects FIG. 1 shows the principle structure of a measurement point selection device for an electron beam tester according to the present invention. This measurement point selection device for electron beam tester is
It has the following components:

Reference numeral 1 denotes measurement wiring designation means, which designates measurement wiring. This specification is made using, for example, a net name.

Reference numeral 2 denotes a wiring design data storage means, which stores CA consisting of design data representing the shape and arrangement of wiring, such as a net list, layout data, and cross mapping.
D data is stored.

Reference numeral 3 denotes a wiring data extracting means, which reads out from the wiring design data storage means 2 design data corresponding to the designated measurement wiring and design data corresponding to the wiring adjacent to the measurement wiring.

Reference numeral 4 denotes a measurable uppermost layer wiring extracting means, which extracts data of a measurable uppermost layer wiring portion from the read design data.

Reference numeral 5 denotes a measurement point selection means, which selects a measurement point by the electron beam tester 6 from the extracted measurable top layer wiring data based on the width of the measurement wiring and the interval between the measurement wiring and the adjacent wiring. do.

In the measurement point selection device for an electron beam tester configured as described above, when a measurement wiring is designated by, for example, a net name, a measurement point on the measurement wiring with a small local electric field effect is automatically selected. Therefore, this selection does not require any skill on the part of the operator, and can be performed in a short time.

The measurable uppermost layer wiring extraction means 4 includes:
For example, the extracted design data is converted into image data by associating the wiring hierarchy with the bit position of pixel data. Extract the wiring as the measurable top layer wiring.

[0014] With this configuration, it is possible to easily extract the measurable wiring portion of the uppermost layer. Furthermore, since the imaged wiring data is used, subsequent measurement points can be easily selected.

[0015] The measurement point selection means 5 selects, for example, the center of a circle inscribed in the measurement wiring having the maximum diameter as a measurement candidate point.

[0016] The wider the same potential range around the measurement point, the smaller the local electric field effect, so the measurement candidate point obtained in this way definitely has a smaller local electric field effect.

Further, the measurement point selection means 5 selects the center as a measurement candidate when there is no adjacent wiring within a circle having a reference radius, for example, a radius of 5 μm, centered on the center of a circle inscribed in the measurement wiring. Point.

Normally, if there are no adjacent wiring lines within a circle with a radius of 5 μm, the influence of the local electric field effect can be ignored, so the measurement candidate points obtained in this way will definitely have a small local electric field effect.

The measurement point selection means 5 selects, for example, the center of a circle inscribed in the measurement wiring with the maximum diameter as a measurement candidate point, and from such measurement candidate points further selects a center of the measurement candidate point. Select a wire that has no adjacent wiring within a circle with a reference radius of .

[0020] With this configuration, the local electric field effect is further reliably reduced.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 is a block diagram showing the configuration of a measurement point selection device for an electron beam tester. In this measurement point selection device, when the operator specifies the net name of the measurement wiring to the computer 12 from the keyboard 10, the computer 12 reads the wiring design data corresponding to the specified net name from the external storage device 14, and selects the wiring from the measurement wiring. A measurement point with a small local electric field effect is selected and supplied to the electron beam tester 16.

The hardware of the computer 12 has a well-known configuration, and FIG. 2 shows its software configuration as functional blocks 12a to 12j.

The external storage device 14 stores CAD data regarding wiring of a semiconductor integrated circuit to be measured. This data includes a netlist 14A representing the logical connection relationship of wires with net names, layout data 14B representing the shape and arrangement of the wires, and netlist 1
Cross mapping 14C that associates 4A with layout data 14B is stored. This CAD data does not need to be specially processed for the measurement point selection device for the electron beam tester, and can be used as is.

The wiring data extraction unit 12a extracts the keyboard 1 from the keyboard 1.
The wiring data of the specified net name starting from 0 is saved to external storage device 1.
4, convert it into image data, and write it into the measurement wiring image storage section 12b. The pixel data constituting this image data is represented by the lower five bits of one byte, for example, as shown in FIG.
=0 to 4) represents the presence or absence of the i-th wiring layer. The 0th wiring layer is a substrate. For example, hexadecimal number 2 indicates that wiring exists only in the first wiring layer, and hexadecimal number 12 indicates that wiring exists in the first wiring layer and the fourth wiring layer.

FIG. 4 shows a wiring image simplified for explanation, and the numerical values in the wiring correspond to the above pixel data (16
decimal number). FIG. 2A shows an image of the measurement wiring, which includes the measurement wiring 18 and the measurement wiring 20. The measurement wiring 18 is in the second wiring layer, and the measurement wiring 2
0 exists in the third wiring layer. In FIG. 2, the wiring data extraction unit 12a next selects a region slightly wider than the measurement wiring image area.
For example, the data of adjacent wirings in an area whose periphery is 5 μm wider than the area is read from the external storage device 14, converted to image data, and then stored in the adjacent wiring image storage unit 14.
Store in c. FIG. 4B shows an image of the adjacent wiring, which includes an adjacent wiring 22 and an adjacent wiring 24. The adjacent wiring 22 is in the first wiring layer, and the adjacent wiring 24
exists in the fourth wiring layer.

In FIG. 2, the measurable uppermost layer wiring extraction section 12d extracts a measurable uppermost layer wiring portion from among the measurement wirings. That is, in FIG. 4, from the measurement wirings 18 and 20 shown in (A), the measurement wirings 18 and 20
A wiring portion where there is no adjacent wiring shown in (B) in the layer immediately above is extracted, and its image data is stored in the measurable uppermost layer wiring image storage section 12e shown in FIG. In this example, the measurable uppermost layer wiring image storage unit 12e stores a wiring image including measurement wirings 18, 20a, and 20b as shown in FIG. 4(C). The measurable top layer wiring extraction unit 12d further extracts these measurement wirings 18,
From among 20a and 20b, only the measurement wiring 20a and the measurement wiring 20b, which are the wiring parts of the uppermost layer, are left, and the measurement wiring 1 is
Clear 8. Therefore, the measurable uppermost layer wiring image storage unit 12e stores a wiring image as shown in FIG. 4(D). By visualizing the wiring data in this way, it is possible to easily extract the measurable wiring portion of the uppermost layer.

The first stage measurement point selection unit 12f selects the measurement candidate point with the minimum local electric field effect from the viewpoint that the wider the same potential range around the measurement point, the smaller the local electric field effect. It is selected from the wiring images stored in the layer wiring image storage section 12e and stored in the measurement candidate point storage section 12h. FIG. 5 shows such measurement candidate points in a simplified manner for the sake of explanation. The measurement candidate point is the center of the circle inscribed in the wiring where the diameter is the maximum, and in the case of the measurement wiring 26 including a pad as shown in FIG. , in the case of a bent line measurement wiring 28 as shown in FIG. , becomes a line C connecting the points C1 and C2 at both ends.

If there is only one measurement candidate point as shown in FIG.
Supply to 6.

When two or more measurement candidate points are stored in the measurement candidate point storage section 12h, the second stage measurement point selection section 12i stores the adjacent wiring image storage section 12c and the measurable top layer wiring image. Referring to the wiring image stored in the storage unit 12e, the measurement candidate point storage unit 12h determines whether the measurement candidate point is more than a certain distance away from the adjacent wiring.
A measurement candidate point is selected from among the measurement candidate points stored in the . As shown in FIG. 6, this selection is performed based on whether or not adjacent wirings 32 and 34 exist within a circle having a reference radius, for example, a radius of 5 μm, centered on the measurement candidate point. Normally, if no adjacent wiring exists within a circle with a radius of 5 μm, the influence of the local electric field effect can be ignored.

By selecting measurement candidate points in two stages as described above, in the case of a polygonal line pattern as shown in FIG.
Measurement candidate point B1 is selected from measurement candidate points B1 and B2, and in the case of a straight line pattern as shown in FIG. A measurement candidate line D from points C1 to C3 is selected. This selection process is easily performed because it uses imaged wiring data.

In FIG. 2, the second stage measurement point selection section 12i
If the measurement candidate points can be narrowed down to one through this selection, this is supplied as the measurement point to the electron beam tester 16 via the output section 12g.

When there are a plurality of measurement candidate points as shown in FIG. 6(B), the selection section 12j selects one measurement candidate point from among them at random or according to a certain rule, and outputs it. It is supplied to the electron beam tester 16 via the section 12g. This rule is, for example, to select a measurement candidate point for which the sum of the values of the X and Y coordinates of the measurement candidate point is the minimum, or to select a measurement candidate point that is the maximum distance away from the adjacent wiring.

In this way, by simply specifying the net name of the measurement wiring, a measurement point with a small local electric field effect is automatically selected. The electron beam tester 16 irradiates this measurement point with an electron beam to measure the voltage of the measurement wiring.

Note that the present invention includes various other modifications. For example, measurement wiring can be specified using a terminal name instead of a net name. Alternatively, a configuration may be adopted in which a plurality of measurement candidate points are displayed on the screen and the operator selects one of them without using the selection section 12j.

[0036]

【Effect of the invention】

[0037]

As explained above, according to the measurement point selection device for an electron beam tester according to the present invention, by specifying the measurement wiring by, for example, a net name, measurement points with small local electric field effects on the measurement wiring can be selected. The selection is automatically made, so the selection does not require the operator's skill, and the selection can be done in a short time, which is an excellent effect.

The measurable top layer wiring extraction means converts the extracted design data into image data by associating the wiring hierarchy with the bit position of the pixel data, and detects that there is an adjacent wiring in the layer directly above the measurement wiring. If the configuration is such that the top layer wiring is extracted as the measurable top layer wiring from among the wiring portions that are not measured, it is possible to easily extract the measurable top layer wiring. Since data is used, subsequent measurement points can be easily selected.

If the measurement point selection means is configured to take the center of the circle inscribed in the measurement wiring and has the maximum diameter as the measurement candidate point, the wider the same potential range around the measurement point, the greater the local electric field effect. is small, so the measurement candidate points obtained in this way have the effect that the local electric field effect is reliably small.

[0040] Furthermore, if the measurement point selection means is configured to use the center as the measurement candidate point when there is no adjacent wiring within a circle with a reference radius centered on the center of the circle inscribed in the measurement wiring, this The measurement candidate points obtained in this manner have the effect that local electric field effects are reliably reduced.

The measurement point selection means selects the center of the circle inscribed in the measurement wiring having the maximum diameter as a measurement candidate point, and further selects a measurement candidate point from among these measurement candidate points. If a configuration is adopted in which adjacent wiring does not exist within a circle having a reference radius, the local electric field effect can be further reduced more reliably.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the principle configuration of the present invention.

FIG. 2 is a block diagram of a measurement point selection device for an electron beam tester according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram of one pixel data of a wiring image.

FIG. 4 is an explanatory diagram for extracting measurable uppermost layer wiring.

FIG. 5 is an explanatory diagram of measurement point selection in the first stage.

FIG. 6 is an explanatory diagram of measurement point selection in the second stage.

[Explanation of symbols]

10 Keyboard 12 Computer 12a Wiring data extraction section 12b Measured wiring image storage section 12c Adjacent wiring image storage section 12d Measurable uppermost layer wiring extraction section 12e Measurable uppermost layer wiring image storage section 12f 1st stage measurement point selection section 12g Output Section 12h Measurement candidate point storage section 12i Second stage measurement point selection section 12j Selection section 14 External storage device 16 Electron beam tester 18, 20, 20a, 20b, 26, 28, 30 Measurement wiring 32, 34 Adjacent wiring A, B1 , B2, C1, C2, C3 measurement candidate point C,
D Measurement candidate line

Claims (5)

[Claims] Claim 1: A measurement wiring designating means (1) for specifying a measurement wiring, a wiring design data storage means (2) storing design data representing the shape and arrangement of the wiring, and a wiring design data storage means (2) corresponding to the specified measurement wiring. wiring data extracting means (3) for reading out design data corresponding to the measured wiring and wiring adjacent to the measured wiring from the wiring design data storage means; and a top layer wiring that can be measured from the read design data. Measurable top layer wiring extraction means (4
), measurement point selection means (5) for selecting a measurement point by the electron beam tester (6) from the extracted measurable top layer wiring data based on the width of the measurement wiring and the interval between the measurement wiring and the adjacent wiring. ), a measurement point selection device for an electron beam tester. 2. The measurable top layer wiring extraction means (
4) converts the extracted design data into image data by associating the wiring hierarchy with the bit position of the pixel data, and converts the extracted design data into image data by matching the hierarchy of the wiring and the bit position of the pixel data. 2. The measurement point selection device for an electron beam tester according to claim 1, wherein the upper layer wiring is extracted as the measurable uppermost layer wiring. 3. The measurement point selection means (5) selects the center of a circle inscribed in the measurement wiring, which has the maximum diameter, as the measurement candidate point. Measurement point selection device for electron beam tester. 4. The measurement point selection means (5) is configured to select a measurement point within a circle having a reference radius centered on the center of a circle inscribed in the measurement wiring.
3. The measurement point selection device for an electron beam tester according to claim 1, wherein when there is no adjacent wiring, the center is selected as the measurement candidate point. 5. Claim 4, characterized in that the measurement candidate points of claim 4 are selected from among the measurement candidate points of claim 3.
Measurement point selection device for an electron beam tester as described.