Data erasure device for flash memory, including SSDs.

Abstract

This invention provides a data erasure device that completely erases data from flash memory, including SSDs (Solid State Drives). [Solution] The flash memory data erasure device using a constant temperature bath comprises a heating means (heater) for heating an SSD 8 containing flash memory having an insulating oxide film, and a reducing agent outlet 6 and on / off valve 7 for supplying a reducing agent from a reducing agent supply means that supplies a reducing agent (hydrogen) or reducing gas plasma to the oxide film of the SSD. The SSD is heated to a predetermined temperature by the heating means, and a reducing agent is supplied to the oxide film by the reducing agent supply means, thereby completely erasing the data of the flash memory.

Description

Technical Field

[0001] The present invention relates to a data erasing device that completely erases data in a flash memory including an SSD (Solid State Drive).

Background Art

[0002] Since an SSD has a faster read speed compared to an HDD (Hard Disk Drive) and is also resistant to shock, it has been rapidly spreading as storage for small electronic devices such as personal computers and portable information terminals.

[0003] An SSD uses flash memory as a storage device. Flash memory has the characteristic of retaining the recorded data even when the power is turned off, which is the biggest reason for its rapid spread as storage. However, flash memory reaches its lifespan when, for example, it repeats writing and erasing about several thousand to 10,000 times.

[0004] The reason is that data recording in flash memory records and holds data by storing and releasing electrons in the floating gate. When electrons are put in and out of the floating gate, electrons move through the insulating oxide film, and thus this oxide film gradually deteriorates.

[0005] Therefore, when discarding an SSD in which the oxide film has deteriorated in this way, since the deterioration of the oxide film gradually occurs with the number of write operations, cells that hold correct data also remain. When discarding such an SSD, it is necessary to completely erase the remaining data. In this case, conventionally, an SSD is taken out from a personal computer or the like and physically destroyed. On the other hand, in the case of a magnetic disk device, data erasure is performed, for example, by the method disclosed in Patent Document 1.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

[0007] However, conventional methods for data erasure are time-consuming, require cumbersome procedures, and cannot completely erase the data. [Means for solving the problem]

[0008] The above problems can be solved by providing a flash memory data erasure device including an SSD, which includes an SSD having a flash memory having an insulating oxide film, a heating means for heating the SSD, and a reducing agent supply means for supplying a reducing agent to the oxide film of the SSD, wherein the SSD is heated to a predetermined temperature by the heating means and a reducing agent is sprayed onto the oxide film by the reducing agent supply means to completely erase the data of the flash memory.

[0009] A reducing gas plasma can also be used instead of the reducing agent mentioned above.

[0010] Furthermore, the flash memory data erasure device of the present invention is characterized by using a constant temperature bath that can accommodate multiple SSDs, has the above-mentioned heating means provided inside, and has a supply port for supplying a reducing agent from a reducing agent supply means. [Brief explanation of the drawing]

[0011] [Figure 1] This diagram illustrates a data erasure device for flash memory, including an SSD, according to this embodiment. [Figure 2] This is a circuit diagram of the data erasure device according to this embodiment. [Figure 3] This diagram shows the specific structure of the flash memory inside an SSD. [Modes for carrying out the invention]

[0012] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Figure 1 illustrates a data erasure device for flash memory, including an SSD, according to this embodiment. In the figure, 1 is a constant-temperature chamber that sets the inside of the chamber to a predetermined temperature and performs data erasure of the SSD, and is equipped with a heater 2 and a cooler 3 inside. The heater 2 and cooler 3 are controlled by a temperature control unit 4, and the temperature inside the chamber can be adjusted, for example, within a range of 50°C to 200°C.

[0013] A fan 5 is provided at the top of the heater 2, and the temperature control unit 4 circulates the internal air, which has been set to a predetermined temperature, within the tank.

[0014] A reducing agent outlet 6 is provided at the top of the constant temperature bath 1 for supplying a reducing agent into the bath. Hydrogen is supplied to this reducing agent outlet 6, for example, from a hydrogen cylinder as shown in the attached diagram, via an on-off valve 7. The reducing agent supplied from the reducing agent outlet 6 is not limited to hydrogen; other reducing agents may be used. In addition, reducing gas plasma may be used instead of a reducing agent.

[0015] In Figure 1, 8 represents an SSD containing flash memory, and is not particularly limited in terms of whether or not it has been removed from an electronic device. Furthermore, SSD8 is not limited to a single unit, but may also contain multiple SSDs, and may include cases where multiple individual flash memory units are stored.

[0016] The constant temperature chamber 1 is provided with an inlet 9 and an outlet 10 for the SSD 8. Thus, the data erasure device in this example is configured to transport the SSD 8, which is inserted through the inlet 9, to the outlet 10 for discharge.

[0017] Therefore, as shown in FIG. 1, three loaders (belt conveyors) 13 to 15 are provided. Loader 13 is a loader that places the SSD 8 before data erasure and transports it to the loading port 9 of the thermostat 1. Loader 14 is set at the lower part of the thermostat 1 and is a loader that transports the SSD 8 conveyed to the loading port 9 by loader 13 into the thermostat 1 and transports it to the data erasure position in the thermostat 1. Note that loader 15 is for unloading the SSD 8 for which the complete data erasure process has been completed from the discharge port 10 of the thermostat 1.

[0018] In addition, above loader 13, a sensor 11 for detecting the SSD 8 is arranged. Thereby, the drive of loader 13 is triggered by the detection of the SSD 8 by sensor 11, and a series of operations are performed. Note that sensor 11 is a reflective photoelectric sensor that detects the presence or absence of the inserted SSD 8 based on the presence or absence of reflected light.

[0019] In addition, doors shown in the accompanying drawings are arranged at the loading port 9 and the discharge port 10, and are controlled by a circuit system described later and synchronously opened and closed according to the drive of loaders 13 to 15.

[0020] As shown in FIG. 2, the data complete erasure device of the flash memory including the SSD in this example, as a circuit configuration, includes a temperature adjustment unit 4 that controls the heater 2 and the cooler 3, a control unit 19 of the sensor (photoelectric sensor) 11, a fan drive unit 18 that drives the fan 5, a motor drive unit 16 that drives loaders 13 to 15, and a door motor drive unit 17 that drives the doors shown in the accompanying drawings provided at the loading port 9 and the discharge port 10 up and down, and is controlled by a control unit 21 based on the operation of an operation unit 20 provided in the thermostat 1.

[0021] The control unit 21 is an information processing device that controls the entire data complete erasure device of this example, and includes, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an auxiliary storage device (e.g., SSD: Solid State Drive), and a plurality of interface controllers (IFC), etc. The auxiliary storage device stores, for example, together with the basic software, an application program (hereinafter referred to as the "control application") for functioning as a data complete erasure device that operates on the basic software.

[0022] By the CPU of the control unit 21 reading the control application into the RAM and executing it, the control unit 21 controls the data complete erasure device of this example.

[0023] Also, control information representing the content of control for data erasure is stored, for example, in the auxiliary storage device. In that case, the CPU constituting the control unit 21 identifies the type of the SSD 8 set (specified) by the user and the control information corresponding to this type, and performs control according to the identified control information.

[0024] Hereinafter, the specific processing operations of the data complete erasure device of this example will be described. First, the SSD 8 including the flash memory for which complete data erasure is desired is placed on the loader 13 and conveyed into the thermostat 1. This process drives the loader 13 by the sensor 11 detecting the SSD 8, and based on the detection signal, the control unit 21 controls the door motor drive unit 17 to open the door shown in the attached drawing provided at the carry-in port 9, and carry the SSD 8 into the thermostat 1.

[0025] Thereafter, the loader 14 is driven to convey the SSD 8 to a predetermined position (the solid line position shown in FIG. 1) inside the thermostat 1.

[0026] Next, the operator operates the control unit 20 to set the temperature inside the constant temperature bath 1 to a predetermined temperature. This process involves the control unit 21 transmitting information about the set temperature to the temperature control unit 4. For example, in this example, the temperature can be set within a range of 50°C to 200°C, and the temperature control device 4 controls the heater 2 and cooler 3 to adjust the internal temperature of the constant temperature bath 1 to the specified temperature. Furthermore, the pressure-reducing valve drive unit 22 drives the pressure-reducing valve 12 to reduce the pressure inside the constant temperature bath 1 to a vacuum or a predetermined pressure.

[0027] Subsequently, the aforementioned on-off valve 7 is driven, and the reducing agent is introduced through the reducing agent discharge port 6. Specifically, hydrogen is introduced into the constant temperature bath 1 from the hydrogen cylinder shown in the attached diagram. At this time, the aforementioned pressure-reducing valve drive unit 22 drives the pressure-reducing valve 12, pressurizing the inside of the bath which has been reduced to a vacuum or a predetermined pressure, and introducing hydrogen into the constant temperature bath 1.

[0028] Figure 3 shows the specific structure of the flash memory within the SSD 8. A drain electrode 23 and a source electrode 24 are provided on a semiconductor with an insulator in between, and a gate electrode 26 is formed sandwiched between insulating oxide films 25. In this structure, electrons are stored or released in the float electrode to record and store data.

[0029] For example, when writing data "0", the source electrode 24 and drain electrode 23 are set to ground potential and a high voltage is applied to the gate electrode 26, causing electrons to break through the insulating oxide film 24 and be stored in the float electrode. To erase data (return from "0" to "1"), the gate electrode 26 is set to ground potential and a voltage is applied to the drain electrode 24 and source electrode 23, releasing the electrons from the float electrode.

[0030] However, as data is repeatedly recorded and stored, electrons move through the oxide film 25, causing the oxide film 25 to gradually deteriorate. Eventually, it becomes unable to hold electrons, resulting in a flash memory where some cells can maintain correct data while others cannot.

[0031] Therefore, in this example, a reducing agent (hydrogen) is introduced into the constant temperature bath 1 as described above to remove the deteriorated oxide film 25. Specifically, the reducing agent (hydrogen) introduced into the constant temperature bath 1, which is set to a predetermined temperature as described above, undergoes a chemical reaction with the deteriorated oxide film 35 and performs a reducing action. At this time, the gate electrode 26 on the oxide film 25 is a metal and does not affect the reduction reaction.

[0032] By processing in this way, the oxide film 25 that makes up the flash memory within the SSD 8 is completely removed, and as a result, the data in the storage area is completely erased.

[0033] Subsequently, the door shown in the illustration, located at the discharge port 10, is opened, and the SSD 8, whose data has been erased, is removed from the constant temperature chamber 1 by the drive of the loader 15.

[0034] As described above, the data erasure device for flash memory, including SSDs, according to the present invention can completely erase data remaining in the storage area. Although hydrogen was used as the reducing agent in the above invention, it is not limited to hydrogen. Alternatively, a configuration using reducing gas plasma instead of a reducing agent may also be used.

[0035] In the above description, a reducing agent (hydrogen) is supplied into a constant temperature bath 1 set to a predetermined temperature to remove the deteriorated oxide film 25, thereby removing the deteriorated oxide film 35 by a chemical reaction and erasing the data in the storage area. However, it is also possible to supply an oxidizing agent (for example, oxygen) into the constant temperature bath 1 to grow the deteriorated oxide film in the opposite direction, for example, by generating an oxide film to a thickness greater than a predetermined level, thereby growing it into an insulating film that completely prevents electrons from passing through, and consequently creating a storage area where data cannot be written, and discarding the flash memory including the SSD. [Explanation of symbols]

[0036] 1... Constant temperature bath 2...heater 3...Cooler 4...Temperature control section 5. Fan 6. Reducing agent discharge port 7. Shut-off valve 8. SSD 9... Loading entrance 10··Outlet 11. Sensor 12. Pressure Reducing Valve 13-15 Loader 16. Motor drive unit 17. Door motor drive unit 18. Fan drive unit 19. Sensor drive unit 20...Operation unit 21. Control Unit 22. Pressure Reducing Valve Drive Unit 23. Drain electrode 24. Source electrode 25. Insulating oxide film 26.. Guard gates

Claims

1. An SSD incorporating flash memory having an oxide insulating film, A heating means for heating the SSD, The SSD comprises a reducing agent supply means for supplying a reducing agent to the oxide insulating film of the SSD, A flash memory data erasure apparatus including an SSD, characterized by heating the SSD to a predetermined temperature using the heating means and supplying a reducing agent to the oxide insulating film using the reducing agent supply means to completely erase the data in the flash memory.

2. A data erasure device for a flash memory including an SSD according to claim 1, characterized in that it includes a pressure and depressurization means for depressurizing the SSD and then pressurizing it together with the introduction of the reducing agent.

3. A data erasure device for flash memory including an SSD according to claim 1, characterized in that it uses a constant temperature bath capable of housing a plurality of the SSDs, having the heating means provided inside, and having a supply port for supplying the reducing agent from the reducing agent supply means.

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