The double jet ionizer for ULSI manufacturing processes

A new space charge balance sensor was developed in order to control ion generation in an air ionizer. Conventionally, a charged plate monitor is widely used in order to detect the space charge balance of the air ionizer. However, the charged plate monitor is not suitable for the feedback system for several reasons. The proposed sensor, in spite of its very simple structure, can detect the space charge balance instantly with enough sensitivity, with a shorter response time, and has a possibility of higher spatial resolution compared to a charge plate monitor. An air ionizer control system that can generate a specific quantity of ions at desired locations is considered to be easily implemented by using feedback of the sensed signal to the air ionizer. 

Section: S/n Ratio and Response Timementioning

confidence: 99%

“…In the inspection process, static electricity may cause operation errors. Those phenomena consequently lead to yield reduction [1][2][3][4][5].…”

Section: Introductionmentioning

confidence: 99%

Basic characteristics of a space charge balance sensor using a MOSFET

Sakuyama

Takeuchi

Terashige

et al. 2007

“…Therefore, the users of these air ionizers have to recognize the relationships between those operating conditions and the neutralization performance so that they can use those air ionizers under optimal conditions. The ion generation characteristics of the air ionizer changes with time because of the degradation of the emitter and/or particle adhesion on the emitter tips . So the relationships between the operating conditions and the neutralization performance have to be checked periodically.…”

Section: Introductionmentioning

confidence: 99%

A simulation on neutralization performance of a corona discharge air ionizer by using an equivalent circuit

Okano

Ikehata

Suzuki³

et al. 2019

Corona‐discharge air ionizers have been used to neutralize static electricity on electronic devices during manufacturing and/or inspection processes. The neutralization performance, that is, the neutralizing current density (JW) and the electric field (EW), in work area depends on the operating conditions. Methods for estimating the neutralization performance are required to check them without stopping the production lines. In this paper, we propose an estimation method using an equivalent circuit simulation called the Simulation Program with Integrated Circuit Emphasis (SPICE) for estimating the behavior of positive and negative ions in the generation, transportation, and work areas. In the simulation, the ion generation characteristics are simulated by diodes and resistors. The transportation and accumulation of the ions are simulated by resistors and capacitors, respectively. The annihilation of ions by recombination is simulated by a circuit composed of capacitors and resistors. The simulation results are in good agreement with the experimental results when the distance between the emitter of the air ionizer and the work area is varied. © 2019 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

“…This is because the electric field generated by the electrostatic charge can cause soft errors in the operation of electronic components such as Metal‐Oxide Semiconductor Field ‐Effect Transistors (MOSFETs) or Charge Coupled Devices (CCDs) of the product. A static neutralization system with a corona discharge air ionizer has been widely used to eliminate electrostatic charge and prevent damage . However, the air ionizer itself may be a primary cause of soft errors that arise during inspection, because air ionizers employ a high voltage power supply that generates electric fields strong enough to cause these errors.…”

Section: Introductionmentioning

confidence: 99%

Effects of an electric field shield on the neutralizing characteristics of a corona discharge air ionizer

Okano

2016

The effects of an electric field shield on the electric field noise and neutralizing current of a corona discharge air ionizer were investigated as a means to prevent soft errors during quality control inspections. The neutralizing current and noise voltage were measured for shielded and nonshielded air ionizers using a charged plate monitor. The use of an electric field shield decreased both the neutralizing current and the noise voltage. Therefore, neutralizing current to noise voltage ratio was calculated to evaluate the effect of the shield on the neutralization performance, and this ratio was several times higher for the shielded air ionizer than for the nonshielded air ionizer.