The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
DETAILED ACTION
Specification
The title of the invention is not descriptive. A new title is required that is clearly indicative of the invention to which the claims are directed. The following title is suggested: ENVIRONMENT AWARE WEAK WORDLINE MANAGEMENT AND READ RECLAIM IN NONVOLATILE STORAGE DEVICES.
Claim Rejections - 35 USC § 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
The factual inquiries set forth in Graham v. John Deere Co., 383 U.S. 1, 148 USPQ 459 (1966), that are applied for establishing a background for determining obviousness under 35 U.S.C. 103(a) are summarized as follows:
1. Determining the scope and contents of the prior art.
2. Ascertaining the differences between the prior art and the claims at issue.
3. Resolving the level of ordinary skill in the pertinent art.
4. Considering objective evidence present in the application indicating obviousness or nonobviousness.
Claims 1-2, 10-12, 20 are rejected under 35 U.S.C. 103 as being unpatentable over Cai et al (US PGPUB # 20160372208) in view of KARAKULAK (US PGPUB # 20160148701) further in view of KWAK et al (US PGPUB # 20140068384). With respect to independent claims 1, 11 Cai/KARAKULAK/KARAKULAK discloses: A storage device [storage device - Cai 0005-0006; fig 1-2] comprising:
a memory for storing data [memory - Cai abstract, 0005-0006; fig 1-2]; and
a controller configured to control the memory [controller to control memory - Cai abstract, 0007, 0023; fig 1-2], wherein the controller is configured to:
divide weak wordlines having a number of fail bits greater than a predetermined value into a plurality of groups based on the number of fail bits [Cai does not explicitly teach grouping weak wordlines, although Cai teaches identifying weak wordlines as: calculating an effective read disturb by considering both direct neighbor read disturb count and non-direct neighbor read disturb count, selecting a wordline with the largest effective read disturb for test read, and deciding whether to reclaim the data of the block based on the errors on the wordline - Cai 0007, fig 7. Nevertheless in the same field of endeavor KARAKULAK teaches grouping algorithms wherein: A plurality of flash memory wordlines of a flash storage device are divided into a plurality of wordline groups based on read error counts associated with the wordlines – KARAKULAK abstract] [fail bits are not explicitly disclosed as the metric by which wordlines are identified as weak, although Cai teaches identifying weak wordlines using other means including raw error rate, read disturb counts, etc – Cai 0061, 0069-0072, fig 7. Nevertheless in the same field of endeavor KWAK teaches detecting abnormal (weak) wordlines using fail bits – KWAK abstract],
determine, among the plurality of groups based on operating environment information, target group on which a reliability check is to be performed [controller selects a wordline with the largest effective read disturb (where effective read disturb reflects stress caused by read environment for a given wordline, in other words, effective read disturb reads on operating environment information) for test read and deciding whether to reclaim the data of the block based on the errors on the wordline – Cai abstract in view of KARAKULAK abstract teaching grouping wordlines],
perform the reliability check on the target group, and perform a read reclaim operation based on results of the reliability check [The controller selects a wordline with the largest effective read disturb for test read and deciding whether to reclaim the data of the block based on the errors on the wordline - Cai abstract in view of KARAKULAK abstract teaching grouping wordlines].
Cai does not explicitly disclose grouping weak wordlines, although Cai teaches identifying weak wordlines - Cai 0007, fig 7. Nevertheless in the same field of endeavor KARAKULAK teaches grouping algorithms wherein: A plurality of flash memory wordlines of a flash storage device are divided into a plurality of wordline groups based on read error counts associated with the wordlines – KARAKULAK abstract. Additionally, Cai/KARAKULAK does not explicitly disclose fail bits, although Cai teaches identifying weak wordlines using other means including raw error rate, read disturb counts, etc – Cai 0061, 0069-0072, fig 7. Nevertheless in the same field of endeavor KWAK teaches detecting abnormal (weak) wordlines using fail bits – KWAK abstract.
Therefore, Cai/KARAKULAK/KWAK teaches all limitations of the instant claim(s).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the invention to group weak wordlines in the invention of Cai as taught by KARAKULAK because it would be advantageous for improving the reliability and endurance of the overall flash memory cell architecture, making the flash memory suitable for enterprise applications (KARAKULAK 0028).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the invention to consider fail bits for identifying weak wordlines in the invention of Cai/KARAKULAK as taught by KWAK because it would be advantageous for identifying abnormal wordlines to facilitate remediation and improvement of flash memory operation (KWAK 0006).
With respect to dependent claims 2, 12 Cai/KARAKULAK/KWAK discloses wherein the controller is configured to assign a corresponding priority to each of the plurality of groups such that a higher priority is assigned to a group to which the weak wordline with a relatively large number of fail bits belongs [selecting wordlines with highest effective read disturb for test and read reclaim – fig 7] [grouping wordlines based on bit-error counts and associating different read offset so that higher error groups get more aggressive read that is severity/priority based – KARAKULAK fig 8, 14] [abnormal wordlines get higher priority for remedial action – KWAK abstract].
With respect to dependent claims 10, 20 Cai/KARAKULAK/KWAK discloses wherein, in response to determining that the operating environment information indicates an abnormal environment, the controller is configured to determine the target group to include a first group with a highest priority and a second group with a second highest priority [wordlines are prioritized according to their read disturb counts and that may apply to groups of wordlines – Cai fig 5 & 7 in view of KARAKULAK abstract teaching grouping wordlines].
Claims 3-6, 8, 13-16, 18 are rejected under 35 U.S.C. 103 as being unpatentable over Cai/KARAKULAK/KWAK further in view of Chunn (US PGPUB # 20160173136).
With respect to dependent claims 3, 13 Cai/KARAKULAK/KWAK does not explicitly disclose wherein the operating environment information comprises operating temperature. Nevertheless in the same field of endeavor Chunn teaches dynamic adjustment of data protection schemes in flash storage systems based on temp, power off duration and flash age – Chunn title, abstract. Therefore, Cai/KARAKULAK/KWAK/Chunn teaches all limitations of the claim including wherein the operating environment information comprises operating temperature [Chunn title, abstract]. It would have been obvious to one of ordinary skill in the art before the effective filing date of the invention to consider operating temperature in the invention of Cai/KARAKULAK/KWAK as taught by Chunn because it would be advantageous for optimizing the selection and application of appropriate levels of data protection (Chunn 0002).
With respect to dependent claims 4, 14 Cai/KARAKULAK/KWAK/Chunn discloses wherein, in response to a range of change in the operating temperature being greater than or equal to a predetermined set value, the controller is configured to determine that the operating environment information indicates an abnormal environment [Chunn abstract, 0021, fig 5-7].
With respect to dependent claims 5, 15 Cai/KARAKULAK/KWAK/Chunn discloses wherein, in response to a period of time for which the operating temperature is maintained within a specific set temperature range being greater than or equal to a predetermined period of time, the controller is configured to determine that the operating environment information indicates an abnormal environment [Chunn abstract, 0021, fig 5-7].
With respect to dependent claims 6, 16 Cai/KARAKULAK/KWAK/Chunn discloses wherein the operating environment information further comprises information on a read count of the memory, and wherein, in response to the read count exceeding a set value, the controller is configured to determine that the operating environment information indicates an abnormal environment [Cai abstract, fig 7].
With respect to dependent claims 8, 18 Cai/KARAKULAK/KWAK/Chunn discloses wherein the operating temperature comprises at least one of a temperature of the controller or a temperature of the memory [Chunn 0025, fig 3].
Claims 9, 19 are rejected under 35 U.S.C. 103 as being unpatentable over Cai/KARAKULAK/KWAK further in view of Kim (US PGPUB # 20180181326).
With respect to dependent claims 9, 19 Cai/KARAKULAK/KWAK does not explicitly disclose the limitations of the instant claim. Nevertheless in the same field of endeavor Kim teaches increasing a read reclaim count value of memory blocks for which a number of failed bits of read data exceeds a predetermined threshold, and wherein a number of times that SPO occurs is monitored/tracked/counted. – Kim abstract, 0076, fig 5. Therefore, Cai/KARAKULAK/KWAK/Kim teaches all limitations of the claim including wherein the operating environment information comprises information on the number of times that sudden power off (SPO) occurs for a predetermined period of time [Kim abstract, 0076, fig 5], and wherein, in response to the number of times sudden power off (SPO) being greater than or equal to a predetermined value, the controller is configured to determine that the operating environment information indicates an abnormal environment [SPO is abnormal operating condition – KWAK 0005]. It would have been obvious to one of ordinary skill in the art before the effective filing date of the invention to consider a number of times that an SPO occurs in the invention of Cai/KARAKULAK/KWAK as taught by Kim because it would be advantageous for stably supporting read reclaim operations even when SPO occurs repeatedly (Kim 0160).
Claims 7, 17 are rejected under 35 U.S.C. 103 as being unpatentable over Cai/KARAKULAK/KWAK/Chunn further in view of Lee (US PGPUB # 20190220397).
With respect to dependent claims 7, 17 Cai/KARAKULAK/KWAK/Chunn does not explicitly disclose the limitations of the instant claim. Nevertheless in the same field of endeavor Lee teaches calculating a global read count based on multiple measured read counts, and controlling a memory device to perform a read reclaim operation on a victim block. Therefore, Cai/KARAKULAK/KWAK/Chunn/Lee teaches all limitations of the claim including wherein the read count comprises a read count of read operations performed by receiving read commands from an external device and a read count of read operations performed by the controller without a read command from the external device [a controller suitable for measuring read counts of the memory blocks, calculating a global read count based on the measured read counts, and controlling the memory device to perform a read reclaim operation – Lee 0006; foreground/host/external reads vs internal/background reads – Lee 0047-0048; global count is amalgamation of plurality of measured read counts – Lee abstract]. It would have been obvious to one of ordinary skill in the art before the effective filing date of the invention to consider a read count for external reads and controller reads in the invention of Cai/KARAKULAK/KWAK/Chunn as taught by Lee because it would be advantageous for fully understanding the damage done to memory blocks for better informing read reclaim decisions (Lee 0067-0068).
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure.
Li US Patent # 8432732 teaches: Techniques and corresponding circuitry are presented for the detection of wordline leakage in a memory array. In an exemplary embodiment, a capacitive voltage divider is used to translate the high voltage drop to low voltage drop that can be compared with a reference voltage to determine the voltage drop due to leakage. An on-chip self calibration method can help assure the accuracy of this technique for detecting leakage limit.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to MARWAN AYASH whose telephone number is (571)270-1179. The examiner can normally be reached 9a-530p M-R.
Examiner interviews are available via telephone, in-person, and video conferencing using a USPTO supplied web-based collaboration tool. To schedule an interview, applicant is encouraged to use the USPTO Automated Interview Request (AIR) at http://www.uspto.gov/interviewpractice.
If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Rocio del Mar Perez-Velez can be reached on 571-270-5935. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300.
Information regarding the status of published or unpublished applications may be obtained from Patent Center. Unpublished application information in Patent Center is available to registered users. To file and manage patent submissions in Patent Center, visit: https://patentcenter.uspto.gov. Visit https://www.uspto.gov/patents/apply/patent-center for more information about Patent Center and https://www.uspto.gov/patents/docx for information about filing in DOCX format. For additional questions, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). If you would like assistance from a USPTO Customer Service Representative, call 800-786-9199 (IN USA OR CANADA) or 571-272-1000.
/Marwan Ayash/Examiner, Art Unit 2133
/ROCIO DEL MAR PEREZ-VELEZ/Supervisory Patent Examiner, Art Unit 2133