CS244969B1 - Intermediate capacitor analyzer connection - Google Patents

Abstract

The circuit relates to a transient capacitance analyzer suitable for spectroscopy of deep levels in solids. The purpose is to enable the display and evaluation of the capacitance during the entire measurement period. The stated purpose is achieved by connecting the high-frequency generator simultaneously with the excitation block, the reference capacitance input and the control block and by using an evaluation block resistant to impulse awakening. The circuit can find application in measurement technology, in the design and manufacture of devices for diagnosing semiconductor structures in laboratory and operational conditions.

Description

244969

BACKGROUND OF THE INVENTION The present invention relates to the connection of an analyzer to a capacitance suitable for the spectroscopy of deep levels in solids.

For capacitive spectroscopy of deep levels in solids, usually semiconductors, measuring devices are used which include the following mainly: excitation energy source, capacity meter and evaluation device. The source of excitation energy, e.g., current or voltage pulses, light and the like. serves to periodically excite the object under investigation. The capacity meter is intended to monitor the response to excitation, i.e., to redirect the directions to the equilibrium or steady state. By changing the temperature of the object to be examined, a change in the relaxation times of the processes taking place therein is achieved. The evaluation device selects from the component which has a relaxation time close to the chosen one, thereby changing the mono-temperature dependence on the non-monotone and giving it a spectroscopic character. The excitation or current excitation of the object under investigation is provided by one or more pulse generators, the outputs of which are often complicated with the capacitance meter. The relationship between the excitation pulses of the American signal is random, which causes the level of the excitation pulse at the moment it ends to be indeterminate. This may be a "scattered spectrum like noise." The components of the capacitive response evaluated are often only a very small part of the total excitation-induced capacity change. Therefore, they use sensitive capacity meters whose output is excited by excitation. Two-channel box-car averager, lock-in amplifiers or more complex correlators are used as scoring devices. They are only able to handle small input voltages at the required sensitivity. This or, greatly, limits the usable output range of the capacity meter or requires unidirectional separation of the evaluation device. However, separation of the unidirectional component may lead to complex shifts of the zero output voltage level, and at this time will ensure that the useful signal remains within the desired limits if a section is excreted during excitation and recovery after awakening from the capacity scaler. In the use of the [alpha] -in amplifiers and some second-correlators, the presence of a non-zero signal at the input during excitation is quite unacceptable. For these reasons, it is necessary to shorten the time of excitation, the output of the capacitance meter or to disconnect the input evaluation device and to disconnect the measuring signal source as well. These requirements limit the operation of known devices. They cannot be tracked during the excitation. Switching the capacitance meter, the source of the measurement signal, or. The evaluation device is complex and can be a source of disturbing signals.

The above mentioned drawbacks are substantially eliminated by the connection of the transient capacitor analyzer according to the invention, the principle of which is that the high-frequency signal generator is connected to the input-excitation block, to the reference of the capacity meter and to the control-block input. block is connected to the input of the excitation block and to the input of the evaluation block. The evaluation block is formed by at least two memory samples of the analog signal, which are connected to the control block via the input, wherein the outputs of the memory samples of the analog signal are coupled to the inputs of the differential amplifier. Analog signal sample memory outputs are coupled to an analog-digital transducer via analog multiple-xora inputs. The advantage of the invention is that it eliminates the need to switch the source of the measurement signal, the input or output of the capacity meter, or the output of the evaluation device, thereby allowing the display and evaluation of the capacitance during the tubular part of the measurement period, except for the necessary time recovery of the capacity meter after start and after ex-citation impulse. Another advantage is the ability to select more complex samples of the capacitive sample for evaluation and thereby influence the properties of the spectra, e.g. selectivity, sensitivity, and the like.

In the accompanying drawings, FIG. 1 illustrates a block connection of a transition capacity analyzer, FIG. 2 and FIG. 3 illustrate examples of block connection of particular transfer capacity analyzer conversions.

Fig. 1 shows the output of the high frequency generator 1 connected to the input and the excitation block 2, with the reference input of the block-in amplifier 3 used as a capacitance meter and with the input c of the control block 4. the object under investigation and the output f connected with the lock-in amplifier 3, the output of which the evaluation block 5 is connected and, if necessary, an oscilloscope. To exit. A suitable recording device may be connected to the evaluation block 3. The output of the control block 4 is connected to the input j of the excitation block 2 and to the input of the evaluation block 5. The synchronization of the transient capacitor analyzer with the external devices is enabled by the terminal 1 of the control block 4, which may be input or output of the trigger sig. -love. Fig. 2 is an evaluation block 5 represented by a pair of memories 6i, 62 of analog signal patterns, the outputs of which are connected to the inputs ni, 112 of the differential amplifier 7. The memories 61, 62 are connected to the control block 4 via the inputs ki, k2 The block 8 providing the heating measured by the object by the heating element is a block 9 connected to the thermocouple T which serves to measure the temperature.

FIG. 3 illustrates other specific

Claims (3)

no, in which the evaluation block 5 is executed by a group of memories 6i, 62, ... 6, of analog signal sizes, which outputs the multiplexer 10 connected to an analog-to-digital converter 11, the output of which is connected to the microcomputer bus 12, to which a heating element 8 is attached. The temperature measurement block 9 is also connected via a multi-plexer 10 to an analog-to-digital converter 11. The microcomputer 12 via the output port may be coupled to a suitable recording medium or a larger computer. In all of the above examples of the transient capacitor analyzer, the high frequency signal from the high frequency generator 1 is simultaneously fed by a measurement branch, represented by excitation block 2 and capacity meter 3, and control block 4, which allows all control signals to be derived to control excitation block 2 and an evaluation block 5 of this high frequency signal and thus to achieve a defined interrelation of the measurement signal phase and the start or end of the excitation pulses, the occurrence of pulses for triggering external devices, such as at the start of the control block 4, if controlled by an external device. In the examples of the solution of the evaluation block 5, it is possible to process a large range of input signals in that the memory of the samples of the analog signal only responds to the voltage values at the moment of sampling and is designed such that suitable limiting circuits protect against the larger ones. - the deviations from the average strain level samples, and thus before awakening. Therefore, at their input, I can act on signals with a center and instantaneous value within wide limits. The time-averaged samples of the input signal can be processed by sufficient differential amplification. As shown in Fig. 3, the evaluation block may comprise a larger number of channels may be processed linearly by combining them, respectively. use on-patio values on individual memories. As shown in the example in FIG. 3, the use of a micro-computer allows for the control of other functions and con. heating the measured object and the like. The invention can be applied in measuring technology, in the design and manufacture of apparatus for diagnosing semiconductor structures in laboratory and operating conditions. r R E D Μ E T 1. Connecting a capacitance analyzer comprising an excitation block to which a measured object is coupled, a capacitance meter connected to the output of an excitation block, an evaluation block and a control block, characterized in that the generator (1j of the high frequency signal coupled to the input (a) of the excitation block (2), to the reference input (6) of the capacitance meter (3) and to the input (c) of the control block (4) and the output (ij of the control block (4) is connected to the input (j) ) of the excitation block (2) and to the input (k) of the evaluation block (5). 2. Connection according to claim 1, characterized in that the evaluation block (5) is composed of at least two stems (61, 62 ... 6 ') of the analog signal, which are through the inputs (k1, k1, k2,. connected to the control block (4), wherein the analogue signal sample memories (61, 62, ..., 6n) are coupled to the inputs (ni and na) of the differential signal (7) . 3. Connections according to claim 1, characterized in that the analogue signal sample memories (61, 62, ... 6n) are connected via a digital-to-digital converter (11) via inputs (pi, pa, ... p). ) of an analogue multi-plexer (10). 3 sheets of drawings