# US 9,437,312 B2 · Management of write-protected data in a semiconductor memory

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- Number: US 9,437,312 B2
- Document ID: US9437312B2
- Status: Granted
- Kind: B2
- Application number: 12/393,599
- Filed: 2009-02-26
- Published: 2010-08-26
- Granted: 2016-09-06
- Earliest claimed: 2009-02-26
- Assignees: SanDisk IL Ltd.
- Applicants: Donald Ray Bryant-Rich; Tal Sagy
- Inventors: Donald Ray Bryant-Rich; Tal Sagy
- Web page: https://patentgrep.com/patent/US9437312B2

## CPC

- G11C 16/22: Safety or protection circuits preventing unauthorised or accidental access to memory cells
- G11C 7/24: Memory cell safety or protection circuits, e.g. arrangements for preventing inadvertent reading or writing; Status cells; Test cells
- G11C: STATIC STORES (semiconductor memory devices H10B)

## Abstract

Systems and methods of finalizing a semiconductor memory are disclosed. A method includes receiving an instruction to finalize data at a data storage device that includes a controller coupled to a semiconductor memory. The data storage device also includes a status indicator to indicate a finalize status of the semiconductor memory. In response to receiving the instruction to finalize the data at the data storage device, the status indicator is set to a finalize value. Write to the semiconductor memory operations are prevented by the controller in response to the status indicator having the finalize value.

## Claims

### Claim 1

A method comprising:
receiving an instruction to finalize data stored in a data storage device, the data storage device including a controller coupled to a semiconductor memory, the semiconductor memory storing the data and having a write protect pin and a memory type indicator associated therewith that indicates that the semiconductor memory is a re-writable memory;
using the controller to emulate an assertion of the write protect pin after receiving the instruction to finalize the data;
changing the memory type indicator associated with the semiconductor memory to a read-only memory type indicator to finalize the data and to cause the data to be write-protected; and
subsequent to the changing of the memory type indicator, performing at least one cycle of erasing and rewriting the data in the semiconductor memory.

### Claim 2 (depends on 1)

The method of claim 1, further comprising determining whether rewriting the data in the semiconductor memory would enhance data retention in the data storage device.

### Claim 3 (depends on 1)

The method of claim 1, further comprising setting a status indicator to a value indicating that the data is finalized, the value being stored in a persistent memory cell of the data storage device.

### Claim 4 (depends on 3)

The method of claim 3, wherein the persistent memory cell is located at the controller.

### Claim 5 (depends on 3)

The method of claim 3, wherein the persistent memory cell is located at the semiconductor memory.

### Claim 6 (depends on 1)

The method of claim 1, wherein the controller and the semiconductor memory are integrated in a single semiconductor device.

### Claim 7 (depends on 1)

The method of claim 1, wherein the controller is formed on a controller component and the semiconductor memory is formed on a storage component.

### Claim 8 (depends on 1)

The method of claim 1, further comprising after the data is finalized providing status information to a host, the status information indicating that the semiconductor memory is a read-only memory to prevent the host from issuing commands to the data storage device that would change the data.

### Claim 9 (depends on 1)

The method of claim 1, further comprising after the data is finalized providing status information to a host, the status information indicating that data write operations are not supported.

### Claim 10 (depends on 1)

The method of claim 1, further comprising after the data is finalized providing status information to a host, the status information indicating that the semiconductor memory is write-protected to prevent the host from issuing commands to the data storage device that would change the data.

### Claim 11 (depends on 1)

The method of claim 1, further comprising, in response to receiving a query from a host device, reading the memory type indicator and generating at least one of a value that indicates whether data write operations are supported and a value that indicates whether the semiconductor memory is write-protected, based on the memory type indicator.

### Claim 12

An apparatus comprising:
a memory controller; and
a storage interface circuit coupled to the memory controller,
wherein the memory controller is configured:
to finalize data in a semiconductor memory that is coupled to the memory controller via the storage interface circuit, the semiconductor memory having a write protect pin and an associated indicator, the associated indicator indicating that the semiconductor memory is a re-writeable memory;
in response to receiving an instruction from a host to finalize the data in the semiconductor memory, to change the associated indicator to indicate that the semiconductor memory is a read-only memory to finalize the data by causing the data to be write-protected and to emulate an assertion of the write protect pin after receiving the instruction to finalize the data, wherein subsequent to changing the associated indicator, the memory controller is further configured to perform at least one cycle of erasing and rewriting the data in the semiconductor memory.

### Claim 13 (depends on 12)

The apparatus of claim 12, wherein a status indicator is persistently set to a value indicating that the data is finalized in response to finalizing the data.

### Claim 14 (depends on 13)

The apparatus of claim 13, wherein the memory controller includes a one-time programmable memory cell that stores at least a portion of the status indicator as a logical value.

### Claim 15 (depends on 13)

The apparatus of claim 13, wherein the semiconductor memory includes a one-time programmable memory cell that stores at least a portion of the status indicator as a logical value.

### Claim 16 (depends on 13)

The apparatus of claim 13, wherein the memory controller includes a status register configured to store at least one bit of the status indicator.

### Claim 17 (depends on 13)

The apparatus of claim 13, wherein the semiconductor memory includes a flash memory cell and wherein at least one bit of the status indicator is stored in the flash memory cell.

### Claim 18 (depends on 12)

The apparatus of claim 12, wherein the memory controller is further configured to, in response to receiving the instruction from the host, determine whether performing the at least one cycle of erasing and rewriting the data would enhance data retention in the semiconductor memory.

### Claim 19 (depends on 12)

The apparatus of claim 12, wherein the memory controller is further configured to, in response to receiving the instruction from the host, send a value to the host that indicates that the semiconductor memory is associated with a read-only indicator.

### Claim 20 (depends on 12)

The apparatus of claim 12, wherein the memory controller, the storage interface circuit, and the semiconductor memory are integrated in a single semiconductor device.

### Claim 21 (depends on 12)

The apparatus of claim 12, wherein the memory controller is formed on a controller component and the semiconductor memory is formed on a storage component.

### Claim 22

A data storage device comprising:
a memory controller;
a semiconductor memory responsive to the memory controller and having a write protect pin; and
an interface circuit configured to couple to a host system, wherein the memory controller is configured to:
configure the semiconductor memory to be an archival media device by causing data stored therein to be write-protected, wherein causing the data to be write-protected includes:
setting a status indicator to a finalize value to finalize the data in the semiconductor memory in response to receiving an instruction via the interface circuit to finalize the data, wherein the memory controller is further configured to emulate an assertion of the write protect pin after receiving the instruction to finalize the data; and
subsequent to emulating the assertion, performing at least one cycle of erasing and rewriting the data in the semiconductor memory; and
in response to finalizing the data, cause the host system to logically disconnect from the semiconductor memory and to logically reconnect to the semiconductor memory for a status update, wherein the status update includes an indication that the data is finalized.

### Claim 23 (depends on 22)

The data storage device of claim 22, wherein the indication that the data is finalized includes an indication that the semiconductor memory does not support data write operations.

### Claim 24 (depends on 22)

The data storage device of claim 22, wherein the indication that the data is finalized includes an indication that the semiconductor memory is write-protected.

### Claim 25 (depends on 22)

The data storage device of claim 22, wherein finalizing the data includes changing a type of the semiconductor memory from a re-writeable memory type to a read-only memory type.

### Claim 26 (depends on 25)

The data storage device of claim 25, wherein causing the data to be write-protected further includes determining whether performing the at least one cycle of erasing and rewriting the data in the semiconductor memory would enhance retention of the data in the data storage device.

### Claim 27

A method comprising:
receiving an instruction to finalize data stored in a data storage device;
emulating an assertion of a write protect pin of the data storage device; and
subsequent to the emulating of the assertion, performing at least one cycle of erasing and rewriting the data in the data storage device.

### Claim 28 (depends on 27)

The method of claim 27, further comprising configuring the data storage device to prevent the data from being changeable to finalize the data in the data storage device in response to receiving the instruction.

### Claim 29 (depends on 28)

The method of claim 28, wherein finalizing the data includes setting a commands supported indicator to a value indicating that write operations are not supported.

### Claim 30 (depends on 28)

The method of claim 28, wherein finalizing the data includes setting a write protect indicator to a value indicating that the data is write-protected.

### Claim 31 (depends on 28)

The method of claim 28, wherein the data storage device includes a semiconductor memory configured to store the data therein and wherein the at least one cycle of erasing and rewriting the data is performed in the semiconductor memory to enhance retention of the data in the data storage device.

### Claim 32 (depends on 27)

The method of claim 27, further comprising sending status information to a host system to indicate that the data is finalized.

### Claim 33 (depends on 22)

The data storage device of claim 22, wherein prior to receiving the instruction, the memory controller is further configured to track a number of data writes to memory cells of the semiconductor memory.

### Claim 34 (depends on 33)

The data storage device of claim 33, wherein the memory controller is further configured to use the number to determine whether the at least one cycle of erasing and rewriting the data in the semiconductor memory would enhance data retention in the semiconductor memory.

### Claim 35 (depends on 22)

The data storage device of claim 22, wherein the memory controller is further configured to correct data errors in the semiconductor memory.

### Claim 36 (depends on 22)

The data storage device of claim 22, wherein the status indicator is a value stored in a persistent memory cell of the semiconductor memory.

### Claim 37 (depends on 22)

The data storage device of claim 22, wherein the semiconductor memory includes a persistent memory cell.

### Claim 38 (depends on 37)

The data storage device of claim 37, wherein the persistent memory cell is a one-time-programmable (OTP) memory cell.