JPH0772196A - Static potential level measuring instrument - Google Patents

Abstract

PURPOSE:To automatically measure the static potential level of an entire region of an object to be measured with a large surface area and easily evaluate and control the surface potential distribution on a manufacturing line by providing a static potential sensor array and a mapping display means. CONSTITUTION:The static potential level of each part of the surface of an object 2 to be measured is detected according to the relative traveling speed between a static potential sensor array 3 and the object 2 to be measured and each position of the array 3. Measurement data are stored at the memory within a measurement device body 5 and are subjected to mapping processing. Namely, when the threshold of the static potential level of each measurement point is set to, for example, + or -1kV, and the measured static potential level exceeds the threshold, dots are displayed at the measurement points within a CRT display 6, thus mapping static potential level. Then, when the number of dots exceeds a specific value (for example, 100) as a whole, it is judged that the object 2 to be measured was electrified extremely and an alarm signal is output, thus waiting for a judgment for proceeding to a next manufacturing process or not.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic potential sensor for measuring the electrostatic potential level on the surface of an object to be measured such as a semiconductor wafer, a mask plate and a liquid crystal display substrate by using an electrostatic potential sensor array and displaying the distribution state. Level measuring device.

[0002]

2. Description of the Related Art In recent years, rapid progress in manufacturing technology of semiconductors and liquid crystal displays, particularly development of integrated circuit technology, has enabled high density, high integration and power saving of ICs, LSIs, displays, etc. It is possible to improve the economic efficiency and speed up electronic parts of. Along with this, the pattern between elements is becoming finer, and dielectric breakdown due to static electricity and deposition contamination of fine particles are becoming a major problem in quality control.

In a clean room in a factory for manufacturing ICs and the like, various troubles caused by the electrostatic charging phenomenon occur, and these troubles are roughly classified into the following five. (1) Destruction of elements and deterioration of performance (2) Surface contamination of semiconductor wafers, mask plates, glass substrates, etc. due to fine particle deposition (3) Non-uniformity of surface electrostatic potential in spacer particle spraying step in manufacturing process of liquid crystal display Non-uniform distribution of spacer particles due to (4) Malfunction of element due to (1) to (3) above (5) Product yield reduction

From the background as described above, the technology for removing static electricity is becoming more and more important, and the applicant of the present application proposed one of the static electricity removing devices as of July 27, 1993. As a prerequisite for this static electricity removal, it is essential to accurately measure and evaluate the electrostatic potential level on the surface of the object. The reason will be described in detail below.

First, in the case of a liquid crystal display substrate, one substrate often serves as one display unit.
Electrostatic destruction or deposition contamination of particles on a part of the substrate may lead to failure of the entire display unit. Therefore, it is necessary to remove static electricity from the entire surface of the substrate,
For that purpose, it is necessary to measure the electrostatic potential level on the substrate surface to know the electrostatic potential distribution.

On the other hand, liquid crystal displays tend to become larger and larger, and the substrate moves many times on the line in the manufacturing process, so that the electrostatic potential level of a part of the substrate surface was measured to eliminate static electricity. Even then, that portion is recharged by the movement, and as a result, the electrostatic potential distribution on the substrate surface is nonuniform at a certain point. Due to this non-uniformity, the spacer particles may be non-uniformly distributed in the spacer particle spraying step. Therefore, it is necessary to accurately measure the electrostatic potential level over the entire surface of the substrate. However, the large glass substrate 1 flowing on the manufacturing line is required.
It is almost impossible to measure the electrostatic potential level at several tens to several hundreds of points by using the electrostatic potential sensor for each sheet.

Further, in the manufacturing process of the semiconductor LSI, the lithography process is repeatedly performed, and the glass mask pattern is transferred by light exposure each time. that time,
If there is static electricity distribution on the glass mask plate, particles may adhere to the photopotential portion and a mask defect may occur. Therefore, it is necessary to obtain the electrostatic potential distribution on the surface of the mask plate and confirm that there is no abnormality before use.

Further, the diameter of semiconductor wafers such as Si is also increasing year by year, and currently 8 inches is the mainstream.
For the next generation, 10-inch or 12-inch ones will be the mainstream. In the LSI manufacturing process as well, static electricity removal on the surface of the semiconductor wafer is necessary for the reasons described above, and is also essential for eliminating wafer transfer mistakes. In particular, if a film or groove is partially formed on the wafer surface, the electrostatic potential level may increase partially, so it is necessary to accurately measure the electrostatic potential level in order to ensure static elimination. Becomes

Here, Table 1 shows the breakdown voltage of each element with respect to the electrostatic potential level. These elements are also used in a liquid crystal display, and in many cases, MOSFETs having a breakdown voltage of 10 to 100 [V] are arranged in an array. Therefore, electrostatic level monitoring and neutralization is required over the entire surface.

[0010]

[Table 1]

Due to the above-mentioned needs, various electrostatic potential level measuring instruments as described below have been conventionally provided.

(A) Rotating sector static electricity measuring instrument This measuring instrument measures an electrostatic potential level by utilizing an electrostatic induction phenomenon that occurs when a conductor is placed in an electrostatic field.

(B) Current collector type static electricity measuring device In this measuring device, the detector is constituted by a weak radiation source so that α particles are irradiated in the vicinity thereof to ionize air into + and −, and a weak electric field is generated. To form. In this state, when a charged object, which is an object to be detected, is placed in a weak electric field, the principle of applying the principle that ions having a polarity opposite to the charged charge move to carry the charge is applied.

(C) Pulse-synchronized static electricity measuring device This measuring device is arranged so that the charged object, which is an object to be detected, and the sensitive electrode are kept at a constant distance from each other, and the two are opposed to each other. By periodically changing the bundle, the potential of the surface to be measured is taken out as an alternating voltage.

(D) Inductive potential type static electricity measuring instrument This measuring instrument is used for electrostatic potential measurement of a phenomenon in which only a very small current can be detected especially at a high voltage, and it detects an induced potential by an object to be measured. However, a high degree of insulation is required for the detection electrode.

(E) Vibration capacitance type static electricity measuring instrument This measuring instrument is a modulation type electrometer having a capacitor whose capacitance changes periodically and has an advantage that it has little zero-point drift and high sensitivity. have.

[0017]

At present, the measurer individually measures the electrostatic potential level of each part of the object to be measured using the above-mentioned various static electricity measuring devices, and evaluates whether or not this is within an allowable range. It is carried out. However, according to this method, it takes a lot of manpower and time to measure the electrostatic potential level and organize the data, and measurement errors and misalignment are likely to occur.
It is difficult to take measures such as immediately applying the measurement result to the static elimination process on the manufacturing line. Therefore, conventionally, it was practically impossible to evaluate and manage the surface potential distribution on the manufacturing line.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to automatically measure the electrostatic potential level over the entire area of an object to be measured having a large surface area. An object of the present invention is to provide an electrostatic potential level measuring device that facilitates evaluation and management of the surface potential distribution above.

[0019]

In order to achieve the above object, the present invention is arranged above an object to be measured which moves relatively, and measures electrostatic potential levels at a large number of measurement points on the surface of the object to be measured. It is provided with an electrostatic potential sensor array and means for processing a measurement signal from the electrostatic potential sensor array and mapping and displaying the electrostatic potential distribution for each measurement point on the display.

[0020]

In the present invention, the surface of the object to be measured is planarly scanned by the electrostatic potential sensor array that moves relative to the object to be measured, and the electrostatic potential levels at a large number of measurement points are measured. These measurement signals are input to a microcomputer, and after comparison with a threshold value or the like, the electrostatic potential distribution state for each measurement point represented by using dots or the like is mapped and displayed on the display.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration of the electrostatic potential level measuring device of this embodiment. In the figure, reference numeral 1 denotes a belt conveyor which moves at a constant speed, and on the belt conveyor 1, a semiconductor wafer, a mask plate, a liquid crystal display for measuring the electrostatic potential level of each part of the surface, in other words, the electrostatic potential distribution state of the surface. An object to be measured 2 such as a substrate for measurement is placed.

Above the belt conveyor 1, for example, an electrostatic potential sensor array 3 of a vibration capacitance type static electricity measuring device is arranged. The sensor array 3 may be a sensor array of another type of static electricity measuring device. The sensor array 3 is attached to the uniaxial scanner 4, and in a system in which the object to be measured 2 is stationary, the sensor array 3 scans the entire surface of the object to be measured 2 by moving in the left-right direction in the drawing. It is considered to be possible.

Reference numeral 5 denotes a measuring device main body. The main body 5 processes a measurement signal from the sensor array 3, outputs the result to a CRT display 6 or a printer 7, and controls the drive of the uniaxial scanner 4. A computer (not shown) is built in. Further, the measurement result can be transmitted to the outside through a communication interface, so that the measurement result can be centrally managed, and the measurement result can be used in the subsequent static elimination step in the manufacturing process.

Next, the operation of this embodiment will be described. The electrostatic potential level of each part of the surface of the object to be measured 2 is the relative moving speed between the electrostatic potential sensor array 3 and the object to be measured 2 and the array 3.
Detected according to the individual position of the. For example, DUT 2
Is a 40 cm square glass substrate and the sensor array 3
Has a pitch of 20 [mm] and a moving range detection range of 20
If the moving speed is [mm] and the moving speed is 40 [mm / sec], the electrostatic potential level of 400 points can be measured at least 10 [sec]. These measurement data are stored in the memory in the main body 5, and the mapping process as described below is executed.

That is, the threshold value of the electrostatic potential level at each measurement point is set to, for example, ± 1 [kV], and when the measured electrostatic potential level exceeds the threshold value, the CRT is set.
The electrostatic potential level is mapped by displaying a dot at that measurement point in the display 6. FIG. 2 is an example of this mapping. When the total number of dots exceeds a predetermined value (for example, 100), it is determined that the DUT 2 is significantly charged, and an alarm signal is output to determine whether to proceed to the next manufacturing process. Wait for the decision.

The mapping result can be output as a hard copy by the printer 7 if necessary. Further, the number of measurement points, the threshold value for mapping, the number of dots for outputting an alarm signal, etc. can be set arbitrarily. The electrostatic potential level at each measurement point may be increased by one dot each time it exceeds 1 [kV], for example. As a result, it becomes possible to visually recognize that the electrostatic potential level is particularly high in the portion where the dots are dense.

[0027]

As described above, according to the present invention, the surface of the object to be measured is planarly scanned by the electrostatic potential sensor array that moves relative to the object to be measured, and electrostatic potentials at a large number of measurement points are obtained. As each level is measured and the electrostatic potential distribution state at each measurement point is mapped on the display, even relatively large semiconductor wafers and substrates for liquid crystal displays can be automatically surfaced in a short time. It is possible to detect the electrostatic potential level or electrostatic potential distribution over the entire area. Therefore, the charged state can be accurately evaluated, and the subsequent static elimination step can be quickly performed, and the introduction to the manufacturing line is facilitated.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention.

FIG. 2 is an example of mapping showing electrostatic potential distribution.

[Explanation of symbols]

 1 Belt Conveyor 2 Object to be Measured 3 Electrostatic Position Sensor Array 4 Uniaxial Scanner 5 Measuring Device Main Body 6 CRT Display 7 Printer

Claims (1)

[Claims] 1. An electrostatic potential sensor array arranged above a relatively moving object to be measured, for measuring electrostatic potential levels at a large number of measurement points on the surface of the object to be measured, and processing signals measured by the electrostatic potential sensor array. An electrostatic potential level measuring device comprising means for mapping and displaying the electrostatic potential distribution at each measurement point on the display.