JPH0584844B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a pattern line length measuring device for measuring the pattern line length of a circuit pattern formed on an insulating substrate or the like.

[Conventional technology]

Along with advances in semiconductor technology, various devices used in telecommunications and information processing are becoming smaller and lighter, and their manufacturing processes are becoming increasingly automated. In particular, as a technology for interconnecting active elements, passive elements, integrated circuits, individual parts, etc.
Those in which a circuit pattern is formed on an insulating substrate are often used. For example, in the case of semiconductor integrated circuits, wiring has been performed using aluminum vapor deposition. Here, elements such as transistors and resistors formed on a semiconductor substrate are connected using aluminum wires.
However, unevenness occurs in the insulating film or wiring metal on the semiconductor substrate during the manufacturing process of elements, and when a metal or insulating film is further formed on these surfaces, these uneven parts may cause uneven film thickness or unevenness. This will cause discontinuity. This tendency is strong in MOSICs because there is a large step difference between the field insulating film and the gate insulating film.

In some printed wiring boards, wiring is performed by etching copper foil. Here, semiconductor integrated circuits, capacitors, etc. are connected using long and thin copper foils. However, when a circuit is formed on a copper foil on an insulating substrate by photo-etching or the like, short circuits or disconnections may occur in the copper foil due to the adhesion between the mask and the insulating substrate and the management of etching time. In digital circuits, as integrated circuits are mounted in high density, several wires must be connected between their terminals, and this tendency is strong.

Therefore, checking the pattern line length of the wiring, that is, the circuit pattern on these substrates is performed. In other words, this type of pattern line length can be determined by using an electrode prepared facing the outside of the board to be measured and the circuit pattern to be measured, and measuring the capacitance between the two electrodes. It was obtained by calculating the area and then calculating the pattern line length.

[Problem that the invention seeks to solve]

However, in conventional pattern line length measurement, the line length is recognized in the form of an area determined by the width and length of the circuit pattern. Therefore, when determining the presence or absence of a short circuit or disconnection in a circuit pattern, the accuracy deteriorates depending on the location of the short circuit or disconnection, and especially for long patterns, there may be defects in relatively small parts. The drawback was that it was difficult to judge.

[Means for solving problems]

The present invention provides a circuit board under test on which a pattern to be measured is formed, a moving means for moving the circuit board under test to a predetermined position, and a probe that contacts a predetermined location of the pattern to be measured to send and receive electrical signals. , a scattering coefficient measuring device connected to the probe and measuring the coefficients of incident power and reflected power with respect to the pattern to be measured, and a sweep signal generator capable of oscillating a wide range of high frequencies to supply a signal to the scattering coefficient measuring device. a temporary storage circuit that temporarily stores signal changes depending on the frequency obtained from the scattering coefficient measuring device; and an external storage device that stores the signal changes of the temporary storage circuit and also stores comparison data in advance; The moving means, the probe, the scattering coefficient measuring device, the sweep signal generator, the temporary storage circuit, and the external storage device are integrated and controlled, and the measurement results stored in the external storage device are compared with the comparison data to determine the pattern to be measured. It consists of a central processing unit that detects physical shapes.

[Effect]

Since the present invention is configured in this manner, the circuit board under test is moved to a predetermined position, the pattern under test is controlled to come into contact with the probe, and high frequency power is generated from the sweep signal generator to determine the scattering coefficient. Supplies the measuring instrument. Coefficient changes in incident power and reflected power will be measured for this high-frequency power applied through the probe, and these changes will be sequentially memorized.
The quality of the pattern line length is determined by comparing it with data stored separately in advance.

〔Example〕

Embodiments of the present invention will be described with reference to the drawings. The figure is a block diagram showing one embodiment of the present invention. Since the scattering coefficient measuring device 2 is connected to the sweep signal generator 1 which oscillates a wide range of high frequencies,
High frequency power is transferred to and from the circuit board under test 4 by the probe 3 serving as the measurement end.
Changes in the scattering coefficient obtained by the scattering coefficient measuring device 2 are temporarily stored in a temporary storage circuit 5, and sequentially stored in an external storage device 7 via a central processing unit 6. The central processing unit 6 also sequentially moves the table 9 on which the circuit board under test 4 is mounted to the position of the probe 4 via the control circuit 8 . Note that comparison data for a predetermined pattern line length is stored in advance in the external storage device 7.

The operation of one embodiment configured in this manner will be described. In response to a command from the central processing unit 6, the table 9 is moved via the control circuit 8, and the pattern to be measured on the circuit board under test 4 mounted on the table 9 is faced to the position where one end thereof contacts the probe 3. 3 is brought into contact with the pattern to be measured on the circuit board 4 to be tested. The high frequency power generated by the sweep signal generator 1 is applied to the pattern to be measured on the circuit board under test 4 by the probe 3 of the scattering coefficient measuring device 2 . The frequency of the sweep signal generator 1 is changed, and the coefficient change of the incident power and reflected power at each frequency is measured by the scattering coefficient measuring device 2, and the obtained results are stored in the temporary storage circuit 5. When a predetermined result is obtained, the result is transferred to the external storage device 7 and saved as data.
Regarding other patterns to be measured on the circuit board under test 4, the table is moved in the same manner, and the measurement results are sequentially stored in the external storage device 7. Now,
The central processing unit 6 controls a series of these operations, controls the external storage device 7, and stores the data observed in advance using a perfect product with no defects as expected values, or stores the data of the circuit pattern and circuit board material. Information calculated based on physical shape and properties is saved as an expected value. Therefore, by comparing the measurement results of the circuit board under test 4 stored in the external storage device 7 with this separately stored data in the central processing unit 6, the length of the circuit pattern, the number of branches, and the The physical shape of a circuit pattern, including information such as the length of a portion, can be recognized, and the quality of the pattern line length can be determined.

〔Effect of the invention〕

The present invention generates a wide range of high frequencies, and analyzes the physical shape of the circuit pattern, including information such as the length of the circuit pattern to be measured, the number of branches, the length of the branch part, and the electrical characteristics in the ultra-high frequency region. In other words, by replacing it with a combination of distributed constant circuits at high frequencies and recognizing it in the form of measuring scattering coefficients, it is possible to detect minute defects, such as shorts in wiring of less than 1 cm, that cannot be identified by time-domain observation using pulses. Can be measured with precision.

[Brief explanation of the drawing]

The figure is a block diagram showing one embodiment of the present invention. 1... Sweep signal generator, 2... Scattering coefficient measuring device, 3... Probe, 4... Circuit board under test, 5
...Temporary memory circuit, 6...Central processing unit, 7...
External storage device, 8... control circuit, 9... table.

Claims (1)

[Scope of Claims] 1. A circuit board under test on which a pattern to be measured is formed, a moving means for moving the circuit board under test to a predetermined position, and a means for transmitting and receiving electrical signals by contacting a predetermined location of the pattern to be measured. a scattering coefficient measuring device connected to the probe and measuring coefficients of incident power and reflected power with respect to the pattern to be measured; and a sweep capable of generating a wide range of high frequencies to supply signals to the scattering coefficient measuring device. a signal generator, a temporary storage circuit that temporarily stores the signal change depending on the frequency obtained from the scattering coefficient measuring device, and an external storage device that stores the signal change of the temporary storage circuit and also stores comparison data in advance. , the moving means, the probe, the scattering coefficient measuring device, the sweep signal generator, the temporary storage circuit, and the external storage device are integrated and controlled, and the measurement results stored in the external storage device are compared with the comparison data to determine the target object. A pattern line length measuring device comprising a central processing unit that detects the physical shape of a measurement pattern. 2. The moving means includes a table provided with a movable mechanism for moving the measuring point of the pattern to be measured to the position of the probe and bringing it into contact with the probe, and a control circuit that controls the movement of the table based on a signal from the central processing unit. A pattern line length measuring device according to claim 1.