| Project/Area Number |
18K04244
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Multi-year Fund |
|---|
| Section | 一般 |
|---|
| Review Section |
Basic Section 21050:Electric and electronic materials-related
|
|---|
| Research Institution | Tokai University |
|---|
Principal Investigator |
|
|---|
| Project Period (FY) |
2018-04-01 – 2021-03-31
|
| Project Status |
Completed (Fiscal Year 2020)
|
| Budget Amount *help |
¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000)
Fiscal Year 2020: ¥390,000 (Direct Cost: ¥300,000、Indirect Cost: ¥90,000)
Fiscal Year 2019: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000)
Fiscal Year 2018: ¥3,120,000 (Direct Cost: ¥2,400,000、Indirect Cost: ¥720,000)
|
|---|
| Keywords | 不揮発性半導体メモリ / フラッシュメモリ / 電荷トラップ / シリコン窒化膜 / 電子保持特性 / 常磁性欠陥 / 点欠陥 / 欠陥準位 / 不揮発性メモリ / 正孔捕獲 / トラップ準位 / 電荷捕獲膜 |
|---|
| Outline of Final Research Achievements |
(a) In order to improve the reliability and to increase the capacity of flash memories, we have searched for elements that can create deep defect levels in silicon nitride films. First-principles calculations were carried out on the energy band of β-Si3N4 crystal containing an impurity element inside, and it was found that the 3d orbitals of Mn and V atoms generate defect levels in the forbidden band of the β- Si3N4 crystal. Next, memory devices with Mn-doped silicon nitride films were fabricated. It was found that, in the memory devices, the electron retention characteristics at room temperature was slightly improved and the recombination of holes and electrons in the silicon nitride films might be suppressed.
(b) A novel method for determining the energy depth of electrons trapped in silicon nitride films and a method for determining the charge centroid and the density of trapped holes have been developed.
|
| Academic Significance and Societal Importance of the Research Achievements |
本研究の(a)によって，シリコン窒化膜を電荷捕獲膜とするフラッシュメモリの信頼性の向上と大容量化に対し，不純物元素（本研究ではMnとV）のドープが有効な手段と成り得ることを見出した。この知見は，高性能フラッシュメモリの実現のための一つの技術指針を与えると考えられる。
また，(b)で言及した二つの方法によって，不純物元素をドープしたシリコン窒化膜や新規材料の電荷捕獲膜を開発する際に，電子トラップのエネルギー深さと正孔のチャージセントロイド，捕獲可能な最大の正孔密度を比較的容易に求めることが可能となる。これによって，高性能フラッシュメモリの開発を加速できる可能性がある。
|
