KR20190045139A - Data security device for solid state drive - Google Patents

Abstract

The present invention relates to a security device for preventing leakage of data information of a solid state drive, wherein the solid state drive comprises: a flash memory for storing data; a data interface for implementing data communication with a host; and a device controller for controlling a data exchange operation between the flash memory and the host via the data interface, wherein the device controller includes a buffer memory for temporarily storing data derived from the flash memory and data to be recorded to the flash memory. The solid state drive includes a high voltage pulse generating device capable of generating and outputting a control gate breakdown voltage (high voltage pulse in a range of 60V to 240V DC) which can destroy a control gate dielectric film of a memory cell when a user operates a switch separately from the device controller. A memory controller of the flash memory includes a voltage selection circuit capable of selecting and inputting a high voltage pulse of the high voltage pulse generating device to word lines of a memory cell array. When the user turns on the switch, the memory controller is configured to apply the control gate breakdown voltage to the word lines of the memory cell array while sequentially addressing all word lines and bit lines.

Description

Technical Field [0001] The present invention relates to a security device for preventing data leakage of a solid state drive,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data information leakage prevention security device of a solid state drive, and more particularly, to a security information security device for preventing data leakage from data stored in a solid-state drive (SSD) And more particularly, to a security device for preventing leakage of data information of a solid-state drive in which a control gate of an individual memory cell in a flash memory module can be electrically damaged and destroyed by itself.

For the protection of information of an organization or an individual, a corporation, a public institution, a military unit, a financial institution, a group, or an individual using the computer completely deletes the data stored in the storage medium of the computer when using the computer, , Donation, etc. are very important for the management and technical aspects. This is because computers that have expired from schools, government offices, corporations, financial institutions, military units, etc. are frequently leaked in the process of being abandoned or used for sale.

The SSD includes a flash memory module (NAND flash memory module), which is a non-volatile storage device in which stored data is not lost even when the power is turned off. In recent years, flash memory modules have been widely used in mobile devices such as digital cameras, mobile phones and PDAs because of their low power consumption and free input / output of information. In recent years, however, flash memory modules have been used in mass storage devices such as SSD Solid-State Drive) and is rapidly replacing hard disks with computer data persistent storage because of its fast processing speed, quietness, low heat generation, and low power consumption. As described above, there is no data information leakage prevention and storage medium destruction system for SSD in a state where the storage medium is switched to the SSD by the hard disk. On the other hand, there is concern about information leakage stored in SSD due to pre-sale of used SSD loading information devices. It is conceivable to use a degausser, a crusher, or a perforator used for disposal of a conventional hard disk for disposal after the end of use of the SSD. However, DiGau is not available for SSD because it is a dedicated device for hard disk that destroys only the recorded data, not strong circular magnetic field. The crusher is crushed through circular fracture and is used as a dedicated device for the current hard disk. It may be possible to use SSD crushing, but it takes about 10 seconds to process one piece at a time, which is inefficient to handle a large amount of SSD. In addition, it is necessary to sort and separate the various scrap mixed scrap. Therefore, it may cause environmental problems, and it is necessary to purchase rental equipment or separate equipment. When there is no equipment, 100% crushing due to consignment treatment is uncertain. They may be exposed to the risk of information leakage. A perforator is a dedicated device for a hard disk that breaks a circular hole in a hard disk and is not suitable for flash memory packaging in an SSD. Moreover, it is ineffective to rent or purchase these SSD data erasure devices directly from enterprises, public institutions, military units, financial companies, organizations, etc., and it takes a lot of cost and work time. It is difficult to confirm 100% shredding accuracy, but it is difficult to check whether the data storage area has been processed to such a degree that the computer user can not recover the data storage area. . Therefore, there is always a risk of information leakage during consignment processing.

1. Korean Patent Publication No. 10-2006-0118384 (November 23, 2006) 2. Korean Patent Publication No. 10-2009-0023787 (March 03, 2009) 3. Korean Patent Registration No. 10-1447424 (Apr. 29, 2014) 4. Korean Patent Registration No. 10-0932300 (2009.12.08) 5. Korean Patent Registration No. 10-0902310 (Jun. 4, 2009)

The present invention has been made in order to solve the problem of erasing data remaining in the flash memory module of the SSD after termination of use of the SSD as described above. And to provide a data information leakage prevention security device of a solid-state drive in which a user and an administrator can directly select and execute unrecoverable destruction of a data storage area of an SSD flash memory module.

A flash memory module for data storage; a data interface for data communication with a host; a device controller for controlling a data exchange operation between the flash memory module and a host through the data interface; And a buffer memory for temporarily storing data read from the flash memory module and data to be written to the flash memory module by the device controller, the solid state drive comprising: a solid state drive, A control gate dielectric breakdown voltage (high voltage pulse in the range of 60 to 240 volts DC) capable of destroying the control gate dielectric layer of the individual memory cells constituting the flash memory module is generated when the user operates the switch separately from the device controller Classic that can output A voltage selection circuit capable of selecting and inputting a high voltage pulse of the high voltage pulse generator in a word line of the memory cell array is provided in the memory controller of the flash memory module, The memory controller can solve this problem by applying a control gate dielectric breakdown voltage to the word lines of the memory cell array while sequentially addressing all the word lines and bit lines.

The high-voltage pulse generator includes a DC converter electrically connected to an output side of a power supply of the computer to receive a DC power from the power supply and boosting the voltage, and a high-voltage pulse generator electrically connected to an output side of the DC converter, A diode connected in series to the resistor for interrupting the output current of the resistor, a diode connected in series to the relay to allow only the current passing through the relay to flow in one direction, and a diode connected in series to the diode A capacitor connected in parallel with the capacitor to supply a current charged in the capacitor to the flash memory module through a voltage selection switch of the flash memory module; Wiring connected to the circuit (volatge selector) A thyristor for energizing the capacitor; and a thyristor for opening and closing the relay when the user closes the switch for a predetermined time to charge the capacitor, and the thyristor is operated in a state where the capacitor is charged to supply a high voltage charged in the capacitor to the wiring connected to the flash memory module And a pulse voltage controller which is controlled to be controlled to be applied.

The relay is preferably a contactless relay.

The high-voltage pulse generating apparatus may further include an energizing indicator for indicating when the high-voltage pulse generating apparatus generates a high-voltage pulse and outputs the high-voltage pulse to the wiring, the wiring connected between the high-voltage pulse generating apparatus and a volatge selector of the flash memory module .

According to the present invention, since the memory cell of the SSD can be directly and irrecoverably destroyed through the direct selection and high voltage application operation by the computer user or the administrator in the state where the SSD is installed in the computer, There is no need to rent or buy equipment and operate it. Accordingly, not only the cost and time of the SSD storage data discarding process can be saved, but also the information leakage due to the SSD removal can be prevented.

1 is a block diagram of a data information leakage prevention security device of a solid state drive according to an embodiment of the present invention.
2 is a circuit diagram of an example of a high-voltage pulse generator according to the present invention.
3 is a block diagram showing a method of applying the high voltage pulse generator shown in FIG. 2 to a flash memory module.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a security device for preventing SSD data leakage according to the present invention will be described in detail with reference to the accompanying drawings.

The memory cell of a typical flash memory module stores and erases information in a single transistor of a double poly-silicon structure. A memory cell of a dual poly structure is formed in the order of a semiconductor substrate, a tunneling oxide film, a floating gate, a dielectric film, a control gate, a source and drain region, a spacer, and the like. The memory cell has two gates, a floating gate and a control gate. The floating gate and the control gate are separated by a dielectric film, and the floating gate and the silicon substrate are separated by a tunneling oxide film. Data storage of such memory cells is typically implemented by inserting or erasing electrons or holes into the floating gate. That is, since the floating gate is completely isolated by the tunneling oxide film and the dielectric film such as a NO (Nitride-Oxide) or an ONO (Oxide-Nitride-Oxide) dielectric film, the electrons or holes once entering the floating gate, The data will not be lost because the floating gate can not escape. On the other hand, in order to record or erase data, an externally accessible terminal, that is, a voltage applied to the control gate must be guided to the floating gate so that an electric field high at both ends of the tunneling oxide film can be formed. The ratio at which the voltage applied to the control gate is induced in the floating gate is referred to as a coupling ratio (CR). As the coupling ratio increases, the program and erase operation efficiency for the memory cell increases and the voltage to be externally applied decreases There is a number. That is, the control gate is an electrode that serves as an actual gate of a nonvolatile memory having a polysilicon stack structure, and programming and erasing of the device are performed according to the bias state of the electrode. However, since the dielectric film between the control gate and the floating gate is formed to be extremely thin for high integration, if the dielectric breakdown voltage for destroying the dielectric film is applied to the control gate, the dielectric film is damaged and the memory cell does not function. The memory cell operates a program and an erase at a relatively high bias voltage of 20V. However, since the thickness of the dielectric film is extremely thin, the voltage of the memory cell is three times or more higher than the normal driving voltage Gate breakdown voltage) is applied, the dielectric film is destroyed, and the memory cell is no longer functioning. On the other hand, the control gates of the memory cells are used in common with the word lines. Applicants have repeatedly tested that when the dielectric breakdown voltage in the range of 60-240 V is applied to the control gate or word line, the gate dielectric is broken and the word line is short-circuited. The present invention relates to a security device capable of artificially damaging a memory cell of a flash memory module by bypassing an overvoltage blocking circuit.

The embodiment shown in FIG. 1 is a data information leakage prevention security device which can separate the high voltage pulse generator 11 and connect to the solid state drive only when necessary. The high-voltage pulse generator 11 may be formed integrally with the solid-state drive.

1, a solid state drive 1 includes a flash memory module 3 for data storage, a data interface 31 for data communication with a host, A device controller (7) for controlling data exchange between the flash memory module (3) and a host via an interface (31), and a device controller (7) for controlling data exchange between the data read from the flash memory module And a buffer memory (9) for temporarily storing data to be written in the memory module (3). The device controller 7 is electrically connected to the data interface 31 and the flash memory module 3 to transmit and receive data to and from the external host (central processing unit of the computer) and to read / write data to the flash memory module 3 . The data interface 31 of the SSD generally uses SATA (Serial AT Attachment) compatible with the hard disk interface.

3, the flash memory module 3 includes a memory cell array 49 and a memory controller, which includes an X Address Decoder 45 for a word line address, A column decoder (Y Address Decoder) 47 for a bit line address, and a memory control logic 41 for generating various control signals. The row decoder 45 receives a word line address and a word line disable signal from the memory control logic 41 to select a word line. The column decoder 47 receives a bit line address and a bit line disable signal from the memory control logic 41 to select a bit line.

1 and 2, a feature of the present invention is that, in a solid state drive, when the user operates the switch 27 separately from the device controller 7, Voltage pulse generator 11 capable of generating and outputting a control gate breakdown voltage (a high-voltage pulse in the range of DC 60 V to 240 V) capable of destroying the gate dielectric film, and the memory controller 11 of the flash memory module 3 A voltage selection circuit 43 is provided on the word line of the memory cell array 49 so that a high voltage pulse of the high voltage pulse generator 11 can be selected and applied.

3, when the user turns on the switch 27, the memory control logic 41 controls the voltage selection circuit 43 so that the high voltage pulse of the high voltage pulse generator 11 An output is applied to the word line and the row decoder 45 and the column decoder 47 are controlled to sequentially address all the memory cells of the memory cell array 49 by word lines and bit lines, The control gate dielectric breakdown voltage is applied to the word line of the control gate 49.

As shown in FIG. 1, the present invention provides a wiring 5 for bypassing the device controller 7 and applying a high-voltage pulse to the cell transistor word line of the flash memory module 3 Voltage pulse generator for generating a high-voltage pulse to the extent that the dielectric film of the control gate of the memory cell of the flash memory module 3 breaks down due to switching of the user, and outputs the generated high- (11).

The high voltage pulse to the extent that the control gate of the memory cell of the flash memory module 3 breaks down is a voltage in the range of DC 60V to 240V. That is, the memory cell of the flash memory module 3 is composed of a single transistor, and the word line bias voltage rating of each transistor is less than 60V (typically 15V-20V). Thus, when a high voltage pulse in the DC 60V to 240V range is applied to the word line with a bias voltage, the memory cell will break down in the control gate dielectric and become permanently unrecoverable. This point is different from the normal sagging or batch erasing of the memory cell stored data of the flash memory by the control gate bias voltage control.

1, the high voltage pulse generator 11 is connected to the wiring 5 connecting the high voltage pulse generator 11 and the voltage select circuit of the flash memory module 3 And an energizing indicator 39 such as an LED for displaying a high voltage pulse when outputting the high voltage pulse to the wiring 5.

As shown in FIG. 1, only the wiring 5 connecting the high-voltage pulse generator and the flash memory is formed in advance in the SSD 1, and the high-voltage pulse generator 11 is manufactured separately, The connector 37 connected to the wiring 11 and the socket 35 connected to the wiring 5 may be detached from the SSD 1. The high-voltage pulse generator 11 and the wiring 5 may be integrally formed in the SSD 1. 1, reference numeral 33 denotes a SATA power supply terminal.

3, the high-voltage pulse generator 11 is electrically connected to the output side of the power supply 13 of the computer (or the host) to receive the DC power from the power supply 13, A resistor 29 electrically connected to an output side of the DC converter 15 to adjust an output current of the DC converter 15 and a resistor 29 connected in series to the resistor 29, A diode 19 connected in series to the relay 17 for allowing the current passed through the relay 17 to flow only in one direction, a diode 19 connected to the diode 17, A capacitor 23 connected in series with the capacitor 19 to be charged with a voltage capable of damaging the memory cell of the flash memory module 3 by a current flowing through the diode 19, In the capacitor 23, A thyristor 21 for unidirectionally energizing a charged electric current to a wiring 5 connected to a voltage selecting circuit of the flash memory module and a relay for opening and closing the relay 17 for a predetermined time when the user closes the switch 27 The capacitor 23 is charged and the thyristor 21 is operated while the capacitor 23 is charged so that a high voltage charged in the capacitor 23 is supplied to a voltage selection circuit of the flash memory module And a pulse voltage controller 25 for controlling the pulse voltage controller 25 to be applied to the connected wirings 5. The relay 17 is preferably a contactless relay (SSR).

3, in a state in which the SSD is installed in the computer, the computer user or the administrator operates the high voltage pulse generating device 11 by the switch 27, The memory cell of the flash memory can be directly and irrevocably destroyed by applying the high voltage pulse to the flash memory. Therefore, there is no need for a consignment process for an external company, and no rental or purchase of separate equipment is required. Accordingly, not only the cost and time of the SSD storage data discarding process can be saved, but also the information leakage due to the SSD removal can be prevented.

1: SSD 3: Flash memory module
5: Wiring 7: Device controller
9: buffer memory 11: high voltage pulse generator
13: power supply 15: DC converter
17: Relay 19: Diode
21: Thyristor 23: Capacitor
25: pulse voltage controller 27: switch
29: Resistor 31: Data interface
33: Power port 35: Socket
37: Connector 39: Energizing indicator
41: Memory control logic 43: Voltage selection circuit
45: Lower decoder 47: Column decoder
49: Memory cell array

Claims (3)

A solid state drive includes a plurality of flash memory modules,
Each of the flash memory modules constituting the solid state drive includes a memory cell array composed of a plurality of memory cells, a row decoder (X Address Decoder) for a word line address of the memory cell, A Y address decoder for address, and a memory control logic for generating a control signal for the row decoder and the column decoder,
The row decoder receives a word line address and a word line disable signal from the memory control logic to select a word line and the column decoder receives a bit line address and a bit line disable bit from the memory control logic, ) Signal to select a bit line,
Wherein the memory cell comprises a floating gate for receiving electrons or holes and a control gate which is separated by the floating gate and the dielectric film and is accessible from the outside and is a terminal common to the word line,
The solid state drive includes a high voltage pulse that can generate and output a control gate dielectric breakdown voltage capable of breaking the control gate dielectric layer of each memory cell constituting the flash memory array when the user operates the switch. And a memory controller logic of each of the flash memory modules is provided with a volatge selector for selecting and inputting a high voltage pulse of the high voltage pulse generator in a word line of the memory cell array, The memory controller logic sequentially addresses all the memory cells belonging to the memory cell array of the flash memory module by the word line and the bit line while applying the control gate insulation to the word line of each memory cell By applying a breakdown voltage, The floating gate and data protection information leakage of the solid state drive, characterized in that destroying the dielectric layer between the control gate security apparatus of the cell.
The method according to claim 1,
The high voltage pulse generator includes a DC converter electrically connected to an output side of a power supply of a computer to receive a DC power from the power supply and boosting the DC voltage, A diode connected in series to the resistor for interrupting an output current of the resistor; a diode connected in series to the relay for allowing a current passing through the relay to flow only in one direction; A capacitor connected in parallel to the capacitor and connected to the capacitor to supply a current charged in the capacitor to a voltage selection circuit of a flash memory module, selector wire) And the relay is opened and closed for a predetermined time when the user closes the switch, the capacitor is charged, and the thyristor is operated in a state where the capacitor is charged, so that a high voltage charged in the capacitor is supplied to the voltage selecting circuit and a pulse voltage controller for controlling the pulse voltage controller to be applied to the wiring connected to the selector.
3. The method of claim 2,
And an energizing indicator for indicating when the high voltage pulse generating device generates a high voltage pulse and outputs the high voltage pulse to a wiring connected to the flash memory, the wiring connected to a voltage selecting circuit of the flash memory module Security device to prevent data information leakage of solid state drive.

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