JPH02231578A - Method and device for deciding destaticization effect - Google Patents

Abstract

PURPOSE:To obtain a stable decision result by charging a detection electrode, which is arranged in an ion atmosphere, electrostatically and then comparing the time up to when its potential drops to a predetermined potential. CONSTITUTION:When an inspection start is indicated through an external input 8, a timer part 6 closes a switch 2. Consequently, a DC voltage source 3 supplies a specific DC current to the detection electrode 1. At this time, the detection electrode 1, for example, is charged electrostatically for a time ts with a potential VM. The specific time ts is counted by the timer part 6 and then the switch 2 is opened to disconnect the electrode 1 from the DC voltage source 3 electrically. Then a surface electrometer 4 begins to measure the potential of the electrode 1 and the timer part 6 measures the time up to when the potential drops to the predetermined potential ts. Thus, the destaticization effect is decided according to the attenuation characteristics of the potential with time, so the stable decision result is obtained.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a technology that can accurately determine the static elimination effect by detecting the degree of ion concentration in a static elimination process using ion blowing. .

[Conventional technology]

2. Description of the Related Art In the manufacturing process of semiconductor devices, it is known that ion blowing is performed for the purpose of removing static electricity charged on semiconductor wafers, packages, etc. during each processing process. There are two methods of ion production: ions are sprayed directly onto the product using a blower or other spraying means, or ions are blown down from the ceiling of the processing chamber to disperse ions into the atmosphere in which the product is placed. Techniques to satisfy this requirement are known.

By the way, in order to judge the static elimination effect of the above-mentioned ion blow, the surface of an actual product such as a semiconductor wafer or package is charged with static electricity and placed in an ion atmosphere, and whether the expected static elimination effect is obtained or not. was determining whether

[Problem to be solved by the invention]

However, with the above technology, it is difficult to judge without using the actual product, and if the charging characteristics vary depending on the product or the charging conditions are different, for example, the manufacturing equipment may be moved, or the ion source (such as a blower) ), it was not possible to immediately respond to changes in the work environment due to abnormalities in the ion generator, etc.

In addition, as this type of ion detection technology,
There is a method described in Japanese Patent No. 113692, but since no consideration was given to the characteristics of potential decay in the sensing electrode, for example, if the amount of static electricity is at a given point in time, how many volts will it be at a certain point in time, what will happen after how many seconds? If the ion concentration is not volt, it cannot be said that the ion concentration is appropriate.
Quantitative measurements such as this have been difficult. Therefore, it has been difficult to accurately control the ion concentration.

The present invention has been made with attention to the above-mentioned problems, and its purpose is to enable quantitative measurement of ion concentration, to appropriately control ion concentration, and to efficiently and reliably remove static electricity. The goal is to provide technology that can be implemented.

The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[Means to solve the problem]

A brief overview of typical inventions disclosed in this application is as follows.

In other words, after charging a detection electrode placed in an ion atmosphere, the ion concentration is determined by comparing the test time (or potential) until a predetermined potential (or test time) is reached with a reference value. This is to detect the suitability of the

[Effect]

According to the above-described means, since the static elimination effect is determined based on the attenuation characteristic of the potential over time at the sensing electrode, a stable determination result can be obtained and the reliability of the determination can be improved. Therefore, it becomes possible to appropriately control the ion concentration, and it becomes possible to realize reliable static elimination from the object to be processed.

As a result of the above, it is possible to prevent electrostatic damage to the object to be processed during the manufacturing process, and to provide a highly reliable product.

〔Example〕

FIG. 1 is a block diagram showing the configuration of a static elimination effect determining device according to an embodiment of the present invention, and FIGS. 2 and 3 are explanatory diagrams showing potential attenuation characteristics at a sensing electrode.

The static elimination effect determining device of this embodiment is as shown in FIG. 1, and includes a sensing electrode 1 that is periodically charged with electric charge, and a predetermined electric charge is supplied to the sensing electrode l via a switch 2. It is comprised of a DC voltage source 3, a surface electrometer 4 that measures the potential of the sensing electrode 1 at any time, and a control section 5 that performs main control of the device.

The detection electrode 1 is a part that is exposed to an ion atmosphere and causes neutralization of charged charges and ions in the atmosphere, and is electrically insulated from other parts of the device. There is.

The control section 5 has a timer section 6 as a counting means, and the output from the timer section 6 is compared with an inspection time signal from an external human power 8 in a comparison section 7, and when a predetermined inspection time is reached, The output of the surface electrometer 4 is sent from the comparison section 7 to the output section I.
It is configured to output to O.

Further, the timer unit 6 is used not only for counting the above-mentioned inspection time but also for timing the supply of charge to the sensing electrode 1.

Note that each of the mechanisms described above is supplied with a predetermined operating voltage from the main power supply section 11.

The output section 10 is composed of a microcomputer system equipped with, for example, a microprocessor and memory, and based on the output signal from the comparison section 7, as will be described later,
It is designed to determine whether the ion concentration is appropriate. If there is an abnormality as a result of the determination by the output unit 10, the output unit 10 notifies the operator using an LED or a buzzer, and also controls the output of the ion source (not shown).

Next, a specific determination method using the above-described static elimination effect determination device will be described using FIG. 2.

First, an attenuation characteristic curve B serving as a reference (threshold value) is determined by the following method.

First, when an instruction to start the test is given through the external human power 8, the timer unit 6 closes the switch 2. As a result, a predetermined DC current is applied to the sensing electrode 1 from the DC voltage source 3.
supplied for. At this time, for example, as shown in FIG. 2, the sensing electrode 1 is charged with a potential of vx for a time t. After a predetermined time t has elapsed as determined by the timer section 6, the switch 2 is opened and the sensing electrode 1 and the DC voltage source 3 are electrically disconnected. Next, the surface electrometer 4 starts measuring the potential of the sensing electrode 1, and the timer section 6 measures the time until this potential attenuates to a predetermined potential V.

This measurement of time t, is repeated a plurality of times, and these measured values are averaged to determine the value of 1.

Further, a time obtained by adding a predetermined margin time Δ1 to this 1, ie, t+Δt, is calculated and used as the determination time.

Next, the determination time 1, +Δt, obtained as above,
A case will be described in which the actual static elimination effect is determined based on the following.

First, it is assumed that the same measurement as in the case of curve B above is carried out, and the time tA until the potential decays to V, is obtained from the characteristic curve shown in A in FIG. In this case, tA<1, +ΔtJ
It can be seen that the charge on the detection electrode 1 is more actively neutralized with the ions in the atmosphere than in the case of the reference characteristic curve B, and that the ion concentration in the atmosphere is appropriate.

Next, it is assumed that the characteristic curve shown in FIG. 2C is obtained, and the time tc until the potential decays to VB is obtained. In this case, 1
c>1, +Δt, and the charge on the sensing electrode 1 is not sufficiently neutralized with the ions in the atmosphere, and the ion concentration is determined to be abnormal.

In such a case, the output unit 10 notifies the operator of the abnormality in ion concentration using an LED or a buzzer, but the output unit 10 may directly control the ion source.

In the above embodiment, the ion concentration is determined by comparing the time required to reach a predetermined potential Vs with the determination time 1, +ΔtJ.
As shown in the figure, a reference time t may be fixedly determined in advance, and the suitability of the ion concentration may be determined based on whether the potential of the sensing electrode exceeds the judgment potential VJ +ΔV at this reference time 1s. .

In the example shown in FIG. 3, when the characteristic curve A is shown, the potential VA at the reference time 1 s is vA<V+ΔVJ
Since the static elimination effect is remarkable, the ion concentration is appropriate, and in the case shown by characteristic curve B, VA>V. +ΔV
, and it is determined that the ion concentration is abnormal due to insufficient neutralization of the discharge. Thus, according to this embodiment, the static elimination effect is determined based on the attenuation characteristic of the potential over time at the sensing electrode 1. Therefore, stable determination results can be obtained.

Therefore, it becomes possible to appropriately control the ion concentration, and it becomes possible to realize reliable static elimination in a semiconductor wafer or a package of a semiconductor device.

As a result of the above, it is possible to prevent electrostatic damage to the semiconductor chip during the manufacturing process, and to provide a highly reliable semiconductor device.

Furthermore, since the ion concentration can be determined without directly using a semiconductor device as a product, inspection efficiency can be improved.

Although the invention made by the present inventor has been specifically explained above based on Examples, it goes without saying that the present invention is not limited to the above Examples and can be modified in various ways without departing from the gist thereof. Nor.

For example, for convenience of explanation, in the example, a case was explained in which the suitability of the ion concentration was determined by one measurement. However, after one measurement, the detection electrode l is charged again and the determination is repeated continuously. By determining whether or not the ion concentration is appropriate based on the results of multiple measurements, a more reliable determination can be made.

In the above explanation, the invention made by the present inventor was mainly applied to the field of application, which is the technique for determining the static elimination effect in the manufacturing process of semiconductor devices, but the present invention is not limited to this, and may be applied to other applications. It can be widely applied to the determination of the static elimination effect of static elimination means using ion blow.

〔Effect of the invention〕

A brief explanation of the effects obtained by typical inventions disclosed in this application is as follows.

That is, according to the present invention, since the static elimination effect is determined based on the attenuation characteristic of the potential over time at the sensing electrode, a stable determination result can be obtained and the reliability of the determination can be improved. Therefore, it becomes possible to appropriately control the ion concentration, and it becomes possible to realize reliable static elimination from the object to be processed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a static elimination effect determining device according to an embodiment of the present invention, and FIGS. 2 and 3 are explanatory diagrams showing potential attenuation characteristics at the detection electrode. DESCRIPTION OF SYMBOLS 1... Sensing electrode, 2... Switch, 3... DC voltage source, 4... Surface electrometer, 5... Control unit, 6...
Timer section, 7... Comparison section, 8... External input, lO.
... Output section, 11... Main power supply section. Figure 1 Figure 2 Time t - ÷

Claims (1)

[Claims] 1. Static neutralization that detects whether the ion concentration is appropriate by comparing the time it takes for the potential to decay to a predetermined potential after charging a detection electrode placed in an ion atmosphere. How to judge effectiveness. 2. Static neutralization that detects whether the ion concentration is appropriate by charging the sensing electrode placed in an ion atmosphere and then comparing the surface potential of the sensing electrode after a predetermined inspection time has elapsed. How to judge effectiveness. 3. A sensing electrode exposed to an ionic atmosphere, a surface electrometer that measures the surface potential of the sensing electrode, and a DC voltage source that supplies DC current to the sensing electrode to put the sensing electrode in a pseudo-charged state;
A static elimination effect determination device comprising: a control unit that detects suitability of ion concentration by comparing a time (or potential) at a time when a predetermined potential (or inspection time) is reached with a reference value.