RU2460083C1 - Device to monitor semiconductor products by second derivatives of current-voltage and volt-coulomb characteristics - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: device to monitor semiconductor products by second derivatives of current-voltage and volt-coulomb characteristics comprises an analogue-digital converter (ADC), a computer, a monitor, a digital-analogue converter (DAC), a control circuit, a unit of biharmonic signal generation, the outlet of which is connected to an inlet of the semiconductor product, and the inlet is connected to the first outlet of the control circuit, a controlled voltage source (CVS), the outlet of which is also connected to the inlet of the semiconductor product, and the inlet is connected to the second outlet of the control circuit, a unit of measurements of an information signal, the inlet of which is connected to the outlet of the semiconductor product, and the outlet is connected to the inlet of ADC.

EFFECT: invention makes it possible to increase sensitivity to detection of hidden defects and to increase functional capabilities of semiconductor product monitoring using additional primary diagnostics information in the form of the second derivative of the volt-coulomb characteristic.

1 dwg

Description

The invention relates to the field of microelectronics, in particular to devices for monitoring and diagnostics of semiconductor products (PPI), such as diodes, transistors and integrated circuits. The device can be used both in the manufacturing technology of PPI, and for the analysis of products from consumers.

There are many known methods for controlling the quality and reliability of PPI (transient characteristics, low frequency noise, etc.). The advantage of the method using derivatives of the current-voltage characteristics (CVC) is the relative simplicity of its implementation with high sensitivity to the identification of various hidden defects [1].

The closest analogue is the proposed device in [2]. The block diagram of a device for controlling the I – V characteristics, proposed in [2], contains a linearly varying voltage generator (GLIN), an investigated PPI, a power supply, a control and start-up circuit for a GLIN, a current-voltage converter, an analog-to-digital converter (ADC), and a digital-to-analog converter (DAC), electronic computer (computer) and monitor. With the help of this scheme, the I – V characteristic of the investigated PIR is actually measured, and then, using the digital differentiation program, the I – V characteristics are recalculated with the construction of the corresponding graphs and their output to the monitor screen.

However, this device has a disadvantage, which can include a low sensitivity to the identification of latent defects. The indicated drawback is associated with the method of determining the derivatives of the I – V characteristics — by calculation from the measured I – V characteristics. The use of a 12-16-bit ADC in the device does not eliminate this drawback, since due to the presence of noise, the primary information in the form of a CVC cannot be reliably measured with high accuracy. For example, if it is possible to measure the I – V characteristic with a relative error of 1%, then only the highest 7-8 bits of the ADC will contain reliable information, while the values of the remaining lower bits will be distorted by noise.

The purpose of the invention is to increase the sensitivity of the device to detect hidden defects and increase its functionality for monitoring PPI using additional primary diagnostic information in the form of a second derivative of the volt-coulomb characteristic.

This goal is achieved by the fact that they additionally introduce a biharmonic signal generating unit, the output of which is connected to the input of the PPI, and the input is connected to the first output of the control circuit, a controlled voltage source (UIN), the output of which is also connected to the input of the PPI, and the input is connected to the second output control circuits, an information signal measuring unit, the input of which is connected to the output of the PPI, and the output is connected to the input of the ADC.

The proposed block diagram of the device is devoid of these disadvantages and is shown in the drawing. It consists of a unit for generating a biharmonic signal 1, a controlled voltage source (UI) 2, an investigated PPI 3, a control circuit 4, a unit for measuring an information signal 5, an analog-to-digital converter (ADC) 6, a digital-to-analog converter (DAC) 7, and an electronic computer machines (computers) 8 and monitor 9.

The information signal measuring unit 5 measures the amplitude of the current at the difference frequency and the phase shift relative to the reference signal, which uniquely determine the second derivatives of the I – V characteristic and the I – V characteristic (modulation differentiation method). Next, the measurement data are entered into the computer 8 through the ADC 6, which converts the analog information into digital form (using a 10-12-bit ADC fully ensures sufficient measurement accuracy). The biharmonic signal generating unit 1 generates a two-frequency test signal for PPI 3. DAC 7 is designed to control the measurement process. UIN 2 provides a stepwise change in the DC bias voltage in order to remove the second derivatives of the I – V characteristics and the I – V characteristics in a certain voltage range. The control circuit 4 provides adjustment of the constant bias and amplitude of the two-frequency signal. A computer 8, in accordance with the written program, calculates the values of the second derivatives of the current – voltage characteristics and the voltage – voltage characteristics, differential spectra of changes in power and charge, plots their dependences on a constant bias voltage, and displays them on a monitor screen 9.

The device operates as follows. The studied PPI 3 receives a two-frequency test signal from the biharmonic signal generating unit 1. By the command from the computer 8, the amplitude of the two-frequency signal and the constant bias voltage of the UIN 2, which is also supplied to the PPI 3, are set via the DAC 7 and the control circuit 4. the product at the differential frequency, as well as the phase shift with respect to the reference input signal are recorded by the measurement unit of the information signal 5, converted into digital form by ADC 6 and received by computer 8. In accordance with written th program are calculated and plotted second derivatives of VAC and WSS DC bias voltage and outputted to the monitor 9. Additionally calculated and also displayed on the screen changes differential spectra of the product consumed power and charge accumulation.

Information sources

1. Gorlov M.I., Anufriev L.P., Bordyuzha O.L. Ensuring and improving the reliability of semiconductor devices and integrated circuits in the process of mass production. Minsk, 1997, 390 s.

2. Device for monitoring semiconductor products according to derivatives of current-voltage characteristics. Patent RU No. 2308732. - Publ. 10/20/2007

Claims (1)

A device for monitoring semiconductor products according to the derivatives of the current-voltage characteristics, consisting of an analog-to-digital converter (ADC), the output of which is connected to the input of an electronic computer, the first output of which is connected to the monitor, and the second output to the input of the digital-to-analog converter ( DAC), the output of which is connected to the input of the control circuit, characterized in that the biharmonic signal generating unit is additionally introduced, the output of which is connected to the input of the semiconductor product (PPI), and the input connected to the first output of the control circuit, controllable voltage source (UIN), whose output is also connected to the PPI's input, and the input is connected to the second output of the control circuit, power measurement information signal input of which is connected to the output of PTP, and an output connected to the input of the ADC.

Images