• Journal of the Korean Crystal Growth and Crystal Technology
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• v.14 no.2
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• pp.47-49
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• 2004

Gate protection $SiN_x$ as an alternative to a conventional re-oxidation process in Dynamic Random Access Memory devices is investigated. This process can not only protect the gate electrode tungsten against oxidation, but also save the thermal budget due to the re-oxidation. The protection $SiN_x$ process is applied to the poly-Si gate, and its device performance is measured and compared with the re-oxidation processed poly-Si gate. The results on the gate dielectric integrity show that etch damage-curing capability of protection $SiN_x$ is comparable to the re-oxidation process. In addition, the hot carrier immunity of the $SiN_x$ deposited gate is superior to that of re-oxidation processed gate.

• JSTS:Journal of Semiconductor Technology and Science
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• v.14 no.6
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• pp.728-732
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• 2014

Macro-model of magnetic tunnel junction (MTJ) for spin transfer torque magnetic random access memory (STT-MRAM) has been developed. The macro-model can describe the dynamic behavior such as the state change of MTJ as a function of the pulse width of driving current and voltage. The statistical behavior has been included in the model to represent the variation of the MTJ characteristic due to process variation. The macro-model has been developed in Verilog-A.

• ETRI Journal
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• v.36 no.6
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• pp.988-998
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• 2014

For memory-based big data storage, using hybrid memories consisting of both dynamic random-access memory (DRAM) and non-volatile random-access memories (NVRAMs) is a promising approach. DRAM supports low access time but consumes much energy, whereas NVRAMs have high access time but do not need energy to retain data. In this paper, we propose a new data migration method that can dynamically move data pages into the most appropriate memories to exploit their strengths and alleviate their weaknesses. We predict the access frequency values of the data pages and then measure comprehensively the gains and costs of each placement choice based on these predicted values. Next, we compute the potential benefits of all choices for each candidate page to make page migration decisions. Extensive experiments show that our method improves over the existing ones the access response time by as much as a factor of four, with similar rates of energy consumption.

• Journal of Advanced Navigation Technology
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• v.15 no.6
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• pp.1104-1110
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• 2011

The conventional semiconductor equipment has adopted SRAM module as the test pattern memory, which has a simple design and does not require refreshing. However, SRAM has its disadvantages as it takes up more space as its capacity becomes larger, making it difficult to meet the requirements of large memories and compact size. if DRAM is adopted as the semiconductor inspection equipment, it takes up less space and costs less than SRAM. However, DRAM is also disadvantageous because it requires the memory cell refresh, which is not suitable for the semiconductor examination equipments that require correct timing. Therefore, In this paper, we will proposed an algorithm for punctuality guarantee of memory-free inspection equipment using DDR2 SDRAM. And we will Developed memory controller using punctuality guarantee algorithm. As the results, show that when we adopt the DDR2 SDRAM, we can get the benefits of saving 13.5 times and 5.3 times in cost and space, respectively, compared to the SRAM.

• Journal of Astronomy and Space Sciences
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• v.29 no.3
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• pp.315-320
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• 2012

We developed a mass-memory chip by staking 1 Gbit double data rate 2 (DDR2) synchronous dynamic random access memory (SDRAM) memory core up to 4 Gbit storage for future satellite missions which require large storage for data collected during the mission execution. To investigate the resistance of the chip to the space radiation environment, we have performed heavy-ion-driven single event experiments using Heavy Ion Medical Accelerator in Chiba medium energy beam line. The radiation characteristics are presented for the DDR2 SDRAM (K4T1G164QE) fabricated in 56 nm technology. The statistical analyses and comparisons of the characteristics of chips fabricated with previous technologies are presented. The cross-section values for various single event categories were derived up to ~80 $MeVcm^2/mg$. Our comparison of the DDR2 SDRAM, which was fabricated in 56 nm technology node, with previous technologies, implies that the increased degree of integration causes the memory chip to become vulnerable to single-event functional interrupt, but resistant to single-event latch-up.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.05a
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• pp.136-139
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• 2011

The conventional semiconductor equipment has adopted SRAM module as the test pattern memory, which has a simple design and does not require refreshing. However, SRAM has its disadvantages as it takes up more space as its capacity becomes larger, making it difficult to meet the requirements of large memories and compact size. if DRAM is adopted as the semiconductor inspection equipment, it takes up less space and costs less than SRAM. However, DRAM is also disadvantageous because it requires the memory cell refresh, which is not suitable for the semiconductor examination equipments that require correct timing. Therefore, In this paper, we will proposed an algorithm for punctuality guarantee of memory-free inspection equipment using DDR2 SDRAM. And we will produced memory controller using punctuality guarantee algorithm.

• Proceedings of the Korean Magnestics Society Conference
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• 2000.09a
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• pp.61-81
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• 2000

Developed two GMR memory architectures, 1R/0T for high density applications, 2R/5T for high speed applications, Embedded GMR technology shall offer rad hard community, Dynamic Reprogrammability, Rapid System Reconfigurability, Code modification in flight, Embedded GMR technology is promising for commercial applications

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.168-168
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• 2011

정보화 사회가 도래함으로 개인별 정보 이용량이 급격히 증가하였고 스마트폰과 같은 모바일 기기의 개발로 정보 이용량이 최고치를 갱신 중이다. 이러한 흐름 속에 사람들은 빠른 처리 속도와 고도의 저장 능력을 요구하게 되고 이에 따라 새로운 Random Access Memory에 대한 연구가 활발히 진행되고 있다. 현재 Dynamic Random Access Memory (DRAM)가 눈부신 발전과 성과를 이룩하고 있지만 전원 공급이 중단 될 경우 저장된 내용들이 지워진다는 단점을 가지고 있다. DRAM의 장점에 이러한 단점을 보완할 수 있는 차세대 반도체 소자로 주목 받고 있는 것이 Magnetic Random Access Memory (MRAM)이다. DRAM에서 Capacitor와 유사한 기능을 하는 MTJ stack은 tunneling magnetoresistance (TMR) 현상을 나타내는 자기저항 박막을 이용하여 MRAM 소자에 집적된다. 본 연구에서는 MRAM의 자성 재료로 구성된 MTJ stack을 효과적으로 식각하고 우수한 식각 profile을 얻는 동시에 재증착의 문제를 해결하는데 목적을 둔다. 본 IrMn 자성 박막의 식각 연구는 유도결합 플라즈마 반응성 이온 식각 (Inductively Coupled Plasma Reactive Ion Etching: ICPRIE)법을 이용하여 진행되었다. 특히 본 연구에서는 종래의 $Cl_2$, $BCl_3$ 그리고 HBr과 같은 부식성 가스가 아닌 부식성이 없는 $CH_4$가스를 선택하여 그 농도를 변화시키면서 식각하였고 더 나아가 $O_2$를 첨가하면서 그 효과를 극대화하려고 시도하였다. IrMn 자성 박막의 식각 속도, TiN 하드 마스크에 대한 식각 선택도 그리고 profile 등이 조사되었고 최종적으로 X-ray photoelectron spectroscopy (XPS)를 이용하여 식각 메카니즘을 이해하려고 하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2013.05a
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• pp.21-23
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• 2013

Static Random Access Memory (SRAM) using CMOS technology has many advantages. It does not need to refresh every certain time, as a result, the speed of SRAM is faster than Dynamic Random Access Memory (DRAM). This is the reason why SRAM is widely used in almost processors and system on chips (SoC) which require high processing speed. Two basic operations of SRAM are read and write. We consider two basic factors, including the accuracy of read and write operations and the speed of these operations. In our paper, we propose the read and write assist circuits for SRAM. By adding a power control circuit in SRAM, the write operation performed successfully with low error ratio. Moreover, the value in memory cells can be read correctly using the proposed pre-charge method.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.28.2-28.2
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• 2011

Resistance random access memory (ReRAM) is a promising candidate for next-generation nonvolatile memory because of its advantageous qualities such as simple structure, superior scalability, fast switching speed, low-power operation, and nondestructive readout. We investigated the resistive switching behavior of tantalum oxide that has been widely used in dynamic random access memories (DRAM) in the present semiconductor industry. As a result, it possesses full compatibility with the entrenched complementary metal-oxide-semiconductor processes. According to previous studies, TiN is a good oxygen reservoir. The TiN top electrode possesses the specific properties to control and modulate oxygen ion reproductively, which results in excellent resistive switching characteristics. This study presents fully room temperature fabricated the TiN/$TaO_x$/Pt devices and their electrical properties for nonvolatile memory application. In addition, we investigated the TiN electrode dependence of the electrical properties in $TaO_x$ memory devices. The devices exhibited a low operation voltage of 0.6 V as well as good endurance up to $10^5$ cycles. Moreover, the benefits of high devise yield multilevel storage possibility make them promising in the next generation nonvolatile memory applications.