JP2002532714A - Method and apparatus for detecting spatial structural features of a crystal - Google Patents

Abstract

(57) [Summary] In order to detect the characteristics of the spatial structure of a conductive crystal (1), especially a semiconductor, a measured current is supplied to the crystal, and a charge is applied at a crystal location (3) different from the current inlet (4). A measurement of the distribution is made. Information on the spatial structure features is obtained from the relationship between the measured charge distribution and the standard distribution. The crystal is exposed to acoustic vibrations, especially the effects of ultrasound (24), to produce a defined spatiotemporal structural change, which is measured. Apparatus suitable for that purpose is a source electrode (4) for introducing a current into the crystal, a drain electrode (3) for extracting a current from the crystal, and obtaining information on the spatial structure of the crystal from the measured current. And a conductive crystal structure (1) provided with an electronic evaluation circuit (20).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a method for detecting the features of the spatial structure of a conductive crystal, in particular a semiconductor, and an apparatus for carrying out this method.

[0002]

[Prior art]

The structural features of the crystal lattice can be investigated and detected in various ways. A readily conceivable method is direct "observation" of the structure, ie, investigation using an electron microscope. Another known method is X-ray structural analysis. Extremely costly and therefore expensive devices are required for any of the known methods, and the value of these devices only comes into play when the entire investigation has to be carried out.

However, investigating the spatial structure in every detail is only required for certain applications. To obtain clear information about the crystal structure, it is sufficient to detect some specific structural features.

[0004]

[Problems to be solved by the invention]

It is an object of the present invention to show a method in which the features of the crystal structure can be detected very easily without the need for costly equipment.

[0005]

[Means for Solving the Problems]

According to the present invention, a measurement current is supplied to a crystal, a charge distribution is measured at a crystal location different from a current inlet, and information on a spatial structure is obtained from a relationship between the measured charge distribution and a standard distribution. This will solve this problem.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION

 Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

The crystal 1 shown in FIG. 1 schematically shows a part of a semiconductor layer such as, for example, a so-called chip in a semiconductor component. The crystal is provided with individual electrically insulating electrodes 3 on the underside, which are connected as current outlets or drains. The full-surface electrode 4 arranged on the upper surface serves as a current inlet or source.

As is known, the movement of electrons 5 from the electrode 4 through the crystal to the drain 3 causes a flow of electricity in the crystal. During this process, electrons may be more or less diverted within the lattice structure of the crystal. Arrows 7-9 indicate various electron paths. In the path 7, electrons incident on the crystal at the source point are the shortest paths and reach the drain opposite to the incident point.

At the defect location 6 in the crystal that causes a change in space charge, the electrons are turned and follow a trajectory 8 different from the linear path to the other drain, which is directly opposite the incidence location. In other cases, the effect of the defect on the electrons is so strong that the electrons may pass through a highly diverted trajectory 9 and not reach the drain on the other side of the crystal at all.

[0010] The source electrode 4 on the entrance side does not have to be formed as one surface, but can be formed of a plurality of individual electrodes. Both the source and drain electrodes can be variably arranged in a matrix or depending on the particular application, for example for coding purposes.

The defect locations 6 in the crystal are of various natures, for example, defects present in the crystal lattice, such as impurity atoms, lattice defects, or crystals caused by other effects, such as mechanical or acoustic vibrations. The change in the lattice may be, for example, a transition from a vibrating node to a vibrating material.

Thus, the distribution of charge carriers (electrons) 5 arriving at the drain 3 is a mapping of the crystal structure. In a defect-free ideal crystal, the distribution of charge carriers will be exactly uniform. Any deviation points to a defect. The type of defect can be inferred from the type of deviation based on the numerical values obtained by experience.

In particular, it is possible to compensate for deviations due to apparent lattice defects, thus making the crystal usable as a sensor for defects due to external influences. This is done by comparing the deviation of the crystal with the actual individual lattice structure with the scattering properties of the same kind of crystal. However, this homogeneous crystal has an ideal intrinsic lattice structure without scattering, and can therefore be used as a reference standard. Thus, the measured difference between the two represents the individuality of the actual crystal under given external conditions.

This measurement difference is stored as a reference for initializing this actual crystal for future measurements, for example, in the case of a storable semiconductor chip, in the crystal itself. Optionally, if the crystal lattice defects due to external effects are subsequently measured, the stored parameters can thus be used to eliminate or balance the individual crystal properties that affect the measurement result.

Measurement of the charge distribution at the drain can be performed in various ways. The source can be configured as a capacitor or transistor for subsequent electrical scanning.

It is particularly preferred to configure the source as a field-effect transistor that already amplifies the signal. This preferred embodiment is shown in FIG. A layer 17 made of a conductive material is applied on a support 18 made of a semi-insulating material. On the conductive substrate, a series of field effect transistors each including one source 10 ′, a plurality of drains 12, and one gate 16 are formed. The source 10 'has a source contact 11, and the drain 12 has a drain contact 13 for connecting to an operating potential. Similarly, the gate 16 has a gate contact 19.

When the source 10 ′ and the drain 12 are connected to the operating potential, the charge carriers 14 penetrate the crystal lattice structure in the region of the conductive channel 15. Due to the turning or scattering of charge carriers by the actual crystal lattice phenomenon and its various encapsulation defects,
The individual drains receive different characteristic potentials, which collectively form a representative charge image that can be evaluated for the crystal. The evaluation circuit 20 measures the potential of the drain and processes it into a distribution that maps the characteristics of the lattice structure.

In a specific implementation, the number of crystalline substrates is not three as shown, but a large number, for example, 64.
Including drain. Individual field effect transistors can be packaged and bonded very tightly.

As already mentioned, both intrinsic structural features of crystals and structural changes due to external influences can be detected by the above method. An aspect of the external influence that temporarily changes the crystal structure is, for example, applying ultrasonic waves to the crystal. It is known to excite mechanical vibrations in crystals by the action of ultrasonic waves. This is nothing but a periodic change in the spatial lattice structure. These changes correspond to defects having the above-mentioned effect on the charge distribution of the current flowing in the crystal or on the control of the field-effect transistor. Therefore, the crystal can be used as an ultrasonic sensor. The evaluation is performed in the same way as described above for the detection of structural features.

Ultrasound reflected or scattered at a particular structure has information about this structure in the form of an interference pattern. When a crystal is excited and vibrated by such an ultrasonic wave, information is diverted to a periodic change of a crystal lattice structure. In other words, a temporary defect in the crystal is a mapping of a structure that reflects or backscatters ultrasound. Therefore, in the crystal serving as the sensor, it is possible to directly detect information on the structure that reflects the ultrasonic wave by the field-effect transistor that performs reading.

This is of particular importance in using semiconductor crystals in the form of chips to directly detect structures scanned by ultrasound. FIG. 3 shows an ultrasound scan of the finger epithelium
This shows detection of information contained in backscattered or reflected ultrasonic waves by a semiconductor component contained on a so-called chip card 37. In the case of the embodiment shown in FIG. 3, the finger pad abdominal surface of the finger 25 is consciously pressed against the adaptive surface 36 of the chip card 37 on which the biometric test is performed.

DE-A-42222387 describes scanning epithelial structures 26 in the epidermis of the ventral fingertip for the purpose of verifying or identifying a person. However, the system described there is only available in a very specific configuration and can be selected for a series of most important applications, especially for the verification of chip cards.

Verification of a chip card that satisfies all requirements for forgery / illegal use prevention and data protection is also possible only in combination with the present invention.

The arrangement shown in FIG. 3 partially corresponds to the configuration known from DE-A-42222387, with the main difference that the scanning of ultrasound waves which interferes with light or other predetermined electromagnetic waves. Instead, measurement currents must flow through the sensor crystal layer 28, which is arranged in accordance with the meaning of the method and the device according to the invention, and these measurement currents are first applied to the periodicity of the atomic core in the crystal lattice. It is excited on the basis of the arrangement and of its charge potential to cause electromagnetic oscillations, and additionally additionally comprises a sensor crystal layer 2.
8 is temporarily diverted and scattered based on physical measures that actually act on it. The ultrasonic waves 24 are generated by the ultrasonic transducer 23 and are transmitted to the epithelial structure 26 of the finger 25 as a biopsy sample through the main body of the apparatus and the adjacent adapter plate 37 ′ having the sensor crystal layer 28. The adapter plate can also be implemented as a chip card. The backscattered ultrasonic waves 27 pass through an adapter plate 37 ', possibly implemented as a chip card, to the sensor crystal layer 28, where they are detected as described above.

In FIG. 3, the sensor crystal layers 28 are again separately shown beside the device main body 22 for easy viewing. A current is introduced from the controlled current source 10 into the sensor crystal layer 28, and the current distribution is detected by the drain arrangement 29. The drain 29 is connected to a drain charge measurement / amplification unit 30 which scans the measuring point, and this unit itself is connected to a measurement value detection interface 31. From there, the measured value information reaches an electronic evaluation device 32, from its output, possibly a cryptographic processor 33 for encoding the data and an interface module 34 for networking. The evaluation circuit further includes an ultrasonic transmitter 35, which is connected to the ultrasonic transducer 23 and controls its emission.

In a practical application, this arrangement is preferably divided into a fixed function unit and a mobile function unit, wherein the fixed function unit comprises an electronic control unit for ultrasonic generation, an ultrasonic transducer and a device body. In contrast, the electronic evaluation device, the adapter plate and the sensor crystal are located in the mobile function, for example in the chip of a chip card or smart card. Such an arrangement is required, for example, for a biometric-assisted person identification and verification system, together with the authentication of the chip of the chip card as valid.

The devices shown in FIGS. 4 to 6 are various modifications of other embodiments of the chip card reader utilizing the present invention. As already mentioned, physical verification, i.e. authentication of a chip card which satisfies all the requirements of forgery / tamper protection and data protection, is only possible with these devices.

A chip card whose chip is equipped with a microprocessor system has recently been internationally called a “smart card”. This field will be a major application of the technology according to the present invention, as there is a high potential for artificial threats to smart cards. Other applications include personal computers, such as enter keys or PC mice, cell phones, keys for closed systems, automobiles, keys for television sets, and many others.

An ultrasonic transmitter 23 is provided below the card mounting surface 22 at a station where a business operation is performed by the chip card 37, for example, a deposit is withdrawn.
Emit 4 upward. The ultrasonic waves penetrate the card and a finger (finger scan) guided on the card or a finger 25 placed on the card. The finger is placed by the cardholder on a pre-designated surface on the card in the station. Ultrasonic waves are reflected or backscattered by an epithelial structure 26 in the epidermis of the finger pad of the finger 25. The backscattered wave portion again reaches the chip card 37, where it reaches the chip having the sensor crystal layer 28 and located in the card.

The chip of the chip card 37 is a chip used in a chip card as usual with necessary functions for scheduled business activities, and is necessary for ultrasonic detection of the method according to the present invention. A sensor in the form of a matrix of field effect transistors is additionally provided. Usually, a large number of unused transistors are provided on a typical chip that can be used for possible purposes. Otherwise, commercial chips would have to be slightly modified to achieve a suitable transistor matrix.

A properly modified chip is shown in FIG. On a normal semiconductor chip 42 there is a circuit 43 for a particular application that has not been modified. An ultrasonic receiving sensor 44 and an evaluation circuit element 45 for processing detection information are arranged in a chip edge area not required for that purpose. A switching element 46 for detecting the position / clock frequency is additionally provided. Active silicon surfaces, which cause increased costs, are saved by applying the scanning principle.

The sensors in the chip detect the characteristic parameters of the backscattered ultrasound as described above, and these parameters are combined in the chip into a well-defined pattern representing the epithelial structure of the individual, and the stored pattern Is compared to If both patterns are the same, the card user is clearly identified as a valid owner. Only then
The chip deactivates its function to interact with the station via the secure interface 34.

The required electronic functions that must be passed in the circuits on the chip to obtain the recognition pattern from the detection signal that must be compared with the stored pattern from the detection signal and release the function in the same case are the chip design And can be implemented in a variety of ways without any problems by the expert. Therefore, a detailed description of the circuit is omitted here.

FIG. 4 shows an ultrasound scan of the epithelial structure 26 in the epigastric ventral surface of the epidermis of the sample 25 and the detection of the information contained in the reflected ultrasound based on the examination arrangement formed as a scanner. The finger 25 must be slid in a predetermined direction 40 on the test arrangement for the test.

Instead of arranging the receiving sensor on a chip integrated with the card, the receiving sensor can be arranged in the station as shown in FIG. 5 and possibly also as part of a microprocessor chip. it can. In that case, the pattern required for user identification is compared with the pattern stored on the card chip and transmitted to the station via the interface during use.

Instead of placing the ultrasonic transmitter in the station, the ultrasonic transmitter can also be placed on the card as shown in FIGS. 6 and 7. In the embodiment shown in FIG. 6, the sensor arrangement is also integrated with the card chip, whereas in the arrangement shown in FIG. 7, the sensor section is in the station.

Unlike chip card authentication, where it is essential to verify that each user of the card is also a valid card holder with access to functions at any and all stations. The key allows access to only a single protected area or a limited number of protected areas. Upon verification of the authentication, the chip embedded in the key releases or provides the key function, or combination compatible with the lock. The lock can only be opened with this key, which has been adapted by the confirmation of the authentication.

In the embodiment shown in FIG. 9, the chip 49 is a stored closed code (encryption chip).
And with the integrated ultrasonic receiver 50 on the key card 48. at the same time,
An ultrasonic transmitter 51 is arranged on the card. Card 48 is station 52
For example, when inserted in a lock, the information stored in the encryption chip 49 is compared, and when the information matches the information stored in the complementary encryption chip 53 in the lock, an opening is performed.

In the variant shown in FIG. 10, the ultrasonic transmitter 51 is not on the card 48 but in the station 52.

Accordingly, in FIGS. 9 and 10, the physical authentication is checked, for example, by a key card 48. In this example, biometric authentication (identification or verification) is intentionally omitted.

These tests, both the biometric tests described above and the combination of both methods, are of a dynamic nature. They provide in each case the vibrational excitation, which may vary in frequency over a wide band, by the action of ultrasonic waves, to simulate the vibrational behavior of the sample finger or the chip of the chip card or both, or the test arrangement alone or in combination. The vibration behavior combining the above components is also detected based on the formation of each characteristic spectrum in the crystal. Coherent ultrasound allows interference formation in the sense of data preprocessing. Furthermore, a high recognition accuracy, a relatively inexpensive construction mode and reproducibility highlight the advantages of the method according to the invention and the device according to the invention.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of the principles of the present invention.

FIG. 2 is a schematic diagram of one embodiment of the present invention.

FIG. 3 is a schematic diagram of a practical application of one embodiment of the present invention.

FIG. 4 shows an alternative to the embodiment shown in FIG.

FIG. 5 shows another alternative to FIG.

FIG. 6 shows another alternative to FIG.

FIG. 7 shows another alternative to FIG.

FIG. 8 shows a chip modified for use in the present invention.

FIG. 9 shows an implementation of a key / chip card version.

FIG. 10 shows an implementation of a key / chip card version.

[Procedural Amendment] Submission of translation of Article 34 Amendment of the Patent Cooperation Treaty

[Submission date] January 12, 2001 (2001.1.12)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Contents of correction]

[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0003

[Correction method] Change

[Contents of correction]

However, in certain applications, it is not necessary to investigate the spatial structure in every detail. To obtain clear information about the crystal structure, it is sufficient to detect some specific structural features. A micro-mechanical sensor for measuring physical quantities acting from the outside is EP-
A-647832. External mechanical effects cause a measurable change in electrical resistance integrated into the micromechanical structure. A sensor for scanning the surface of a fingertip and converting it directly into an electrical signal is described in U.S. Pat. No. 4,429,413. The core of this sensor is a so-called array of individually transistor of about 0.1 mm ² size. GB-A-1011134 describes a method for testing semiconductor structures for defects by simply measuring resistance in two different directions. However, all of these measurements provide no or only little information about the spatial structure of the semiconductor used or tested as a sensor.

──────────────────────────────────────────────────続 き Continuation of front page (81) Designated country EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, IT, LU, MC, NL, PT, SE ), OA (BF, BJ, CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, GM, KE, LS, MW, SD, SL, SZ, TZ, UG, ZW), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), AE, AL, AM, AT, AU, AZ, BA, BB, BG, BR, BY, CA, CH, CN, CR, CU, CZ, DE, DK, DM, EE, ES, FI, GB, GD, GE, GH, GM, HR, HU, ID , IL, IN, IS, JP, KE, KG, KP, KR, KZ, LC, LK, LR, LS, LT, LU, LV, MD, MG, MK, MN, MW, MX, NO, NZ, PL, PT, RO, RU, SD, SE, SG, SI, SK, SL, TJ, TM, TR, TT, TZ, UA, UG, US, UZ, VN, YU, ZA, ZWF terms (reference 2G047 BA03 BC03 CA01 CA07 EA10 EA11 GD00 2G060 AA15 AE40 AF15 AF20 AG11 AG13 HC10 HE10 KA09 4C301 DD30 EE17 GA20 LL20 4M106 AA02 BA20 CB30

Claims (9)

[Claims] 1. A method for detecting a spatial structure characteristic of a conductive crystal, in particular a semiconductor, wherein a measurement current is supplied to the crystal, and a charge distribution is measured at a crystal location different from a current inlet. Acquiring information on spatial structure features from the relationship between the determined charge distribution and the standard distribution. 2. The method according to claim 1, wherein temporal spatial structure changes are measured and associated with a standard distribution of spatial structures that do not change temporally. 3. The method according to claim 1, wherein the disturbance of the defined temporal spatial structure change is measured. 4. The method according to claim 3, wherein the crystal is exposed to acoustic vibrations to generate a defined temporal and spatial structural change. 5. The method according to claim 1, wherein the crystal is exposed to the influence of ultrasonic waves, the ultrasonic waves changing the spatial structure of the crystal over time. 6. The ultrasonic wave is modulated by an individual reflection structure.
The method of claim 5. 7. The method according to claim 6, wherein the reflecting structure is moved relative to the direction of propagation of the ultrasonic waves. 8. The method according to claim 5, wherein ultrasonic waves are generated in the crystal. 9. An apparatus for performing the method according to claim 1, wherein
A conductive crystal having a source electrode for introducing a current into the crystal, a drain electrode for extracting a current from the crystal, and an electronic evaluation circuit for obtaining information on a spatial structure of the crystal from the measured current. A device characterized by a structure or a semiconductor crystal structure.