公开(公告)号：US06734456B2

公开(公告)日：2004-05-11

申请号：US10287824

申请日：2002-11-05

申请人： Keisuke Tanaka ,  Toru Nasu ,  Masamichi Azuma

发明人： Keisuke Tanaka ,  Toru Nasu ,  Masamichi Azuma

IPC分类号： H01L2976

CPC分类号： H01L21/02197 ,  H01L21/31691 ,  H01L28/55 ,  H01L28/75

摘要： The ferroelectric film of the invention is made from a ferroelectric material represented by a general formula, Bi4−x+yAxTi3O12 or (Bi4−x+yAxTi3O12)z+(DBi2E2O9)1−z, wherein A is an element selected from the group consisting of La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and V; D is an element selected from the group consisting of Sr, Ba, Ca, Bi, Cd, Pb and La; E is an element selected from the group consisting of Ti, Ta, Hf, W, Nb, Zr and Cr; and 0≦x≦2, 0

摘要翻译： 本发明的铁电体膜由通式Bi4-x + yAxTi3O12或（Bi4-x + yAxTi3O12）z +（DBi2E2O9）1-z表示的铁电材料制成，其中A为选自 La，Pr，Nd，Sm，Eu，Gd，Tb，Dy，Ho，Er，Tm，Yb，Lu和V; D是选自Sr，Ba，Ca，Bi，Cd，Pb和La的元素; E是选自Ti，Ta，Hf，W，Nb，Zr和Cr的元素; 0 <= x <= 2,0

公开(公告)号：US06447838B1

公开(公告)日：2002-09-10

申请号：US08543827

申请日：1995-10-16

申请人： Masamichi Azuma ,  Eiji Fujii ,  Yasuhiro Uemoto ,  Shinichiro Hayashi ,  Toru Nasu ,  Yoshihiro Shimada ,  Akihiro Matsuda ,  Tatsuo Otsuki ,  Michael C. Scott ,  Joseph D. Cuchiaro ,  Carlos A. Paz de Araujo

发明人： Masamichi Azuma ,  Eiji Fujii ,  Yasuhiro Uemoto ,  Shinichiro Hayashi ,  Toru Nasu ,  Yoshihiro Shimada ,  Akihiro Matsuda ,  Tatsuo Otsuki ,  Michael C. Scott ,  Joseph D. Cuchiaro ,  Carlos A. Paz de Araujo

IPC分类号： B05D512

CPC分类号： H01L28/75 ,  H01L21/28568 ,  H01L28/55 ,  H01L28/65 ,  Y10T29/42

摘要： A Ti/TiN adhesion/barrier layer is formed on a substrate and annealed. The anneal step is performed at a temperature within a good morphology range of 100° C. above a base barrier anneal temperature that depends on the thickness of said barrier layer. The base barrier anneal temperature is about 700° C. for a barrier thickness of about 1000 Å and about 800° C. for a barrier thickness of about 3000 Å. The barrier layer is 800 Å thick or thicker. A first electrode is formed, followed by a BST dielectric layer and a second electrode. A bottom electrode structure in which a barrier layer of TiN is sandwiched between two layers of platinum is also disclosed. The process and structures also produce good results with other capacitor dielectrics, including ferroelectrics such as strontium bismuth tantalate.

摘要翻译： 在基板上形成Ti / TiN粘合/阻挡层并退火。 退火步骤在取决于所述阻挡层的厚度的基本阻挡退火温度之上的100℃的良好形态范围内进行。 对于约3000的屏障厚度，对于约1000和约800℃的阻挡层厚度，基底阻挡退火温度为约700℃。 阻挡层厚度为800或更厚。 形成第一电极，随后是BST介电层和第二电极。 还公开了其中TiN阻挡层夹在两层铂之间的底部电极结构。 该工艺和结构也与其他电容器电介质（包括铁电锶钽酸锶）等产生良好的结果。

公开(公告)号：US06840443B2

公开(公告)日：2005-01-11

申请号：US10794333

申请日：2004-03-05

申请人： Masamichi Azuma

发明人： Masamichi Azuma

IPC分类号： G05B19/18 ,  G06K5/00 ,  G06K7/00 ,  G06K7/08 ,  G06K17/00 ,  G06K19/06 ,  G06K19/07 ,  G06K19/073

CPC分类号： G06K19/073 ,  G06K19/0707 ,  G06K19/0712 ,  H04L9/3273 ,  H04L2209/56 ,  H04L2209/805

摘要： An IC card 1 having an integrated device includes a nonvolatile memory 12 and an encryption circuit 10. The nonvolatile memory 12 after the IC card 1 is placed in a radio wave zone to receive a power supply from a terminal apparatus through a radio wave. The encryption circuit 10 coordinates with a first terminal apparatus to perform a mutual authentication. The integrated device includes a nonvolatile memory 13 and an encryption circuit 11. The nonvolatile memory 13 is accessed after the IC card 1 is placed at a location close to an antenna in the first terminal apparatus and only after the IC card 1 receives a higher-level power supply from the antenna. The encryption circuit 11 coordinates with the terminal apparatus to perform a mutual authentication. Personal information that requires high security is stored in the nonvolatile memory 13 and the encryption circuit 11 performs a mutual authentication whenever the nonvolatile memory 13 is accessed.

摘要翻译： 具有集成装置的IC卡1包括非易失性存储器12和加密电路10. IC卡1之后的非易失性存储器12被放置在无线电波区域中，以通过无线电波从终端装置接收电力供应。 加密电路10与第一终端装置协调以执行相互认证。 集成装置包括非易失性存储器13和加密电路11.非易失性存储器13在IC卡1放置在第一终端装置中靠近天线的位置之后并且仅在IC卡1接收到较高电平 天线的电平供电。 加密电路11与终端装置协调，进行相互认证。 需要高安全性的个人信息被存储在非易失性存储器13中，并且每当访问非易失性存储器13时，加密电路11执行相互认证。

公开(公告)号：US6133050A

公开(公告)日：2000-10-17

申请号：US405885

申请日：1995-03-17

申请人： Masamichi Azuma ,  Larry D. McMillan ,  Carlos A. Paz de Araujo ,  Michael C. Scott

发明人： Masamichi Azuma ,  Larry D. McMillan ,  Carlos A. Paz de Araujo ,  Michael C. Scott

IPC分类号： C30B29/30 ,  C23C16/44 ,  C23C16/448 ,  C23C16/455 ,  C23C16/46 ,  C23C16/48 ,  C23C16/52 ,  C23C18/12 ,  C23C18/14 ,  C30B7/00 ,  C30B29/68 ,  H01L21/02 ,  H01L21/314 ,  H01L21/316 ,  H01L21/3205 ,  H01L27/108 ,  H01L27/115 ,  H01L21/31

CPC分类号： H01L21/31691 ,  C23C16/4412 ,  C23C16/448 ,  C23C16/4486 ,  C23C16/45561 ,  C23C16/4558 ,  C23C16/46 ,  C23C16/482 ,  C23C16/52 ,  C23C18/1216 ,  C23C18/1225 ,  C23C18/1279 ,  C23C18/1283 ,  C23C18/1295 ,  C23C18/14 ,  C30B29/68 ,  C30B7/00 ,  H01L27/10805 ,  H01L27/11502 ,  H01L28/56 ,  H01L28/60 ,  H01L28/55

摘要： A precursor solution formed of a liquid polyoxyalkylated metal complex in as solvent is applied to a substrate in the formation of a metal oxide thin film. The liquid thin film is baked in air to a temperature up to 500.degree. C. while UV radiation having a wavelength ranging from 180 nm to 300 nm is applied. The thin film can be twice-baked at increasing temperatures while UV radiation is applied at one or both bakings. The film is then annealed at temperature ranging from about 700.degree. C. to 850.degree. C. to produce a thin-film solid metal oxide product. Alternatively, the UV radiation may be applied to the liquid precursor, the thin film may be annealed with UV radiation, or combinations of such applications of UV radiation to the precursor, to the thin film before or after baking, and/or UV annealing may be used. The use of UV radiation significantly reduces the leakage current and carbon impurity content of the final metal oxide.

摘要翻译： 将作为溶剂的液态聚氧化烷基化金属络合物形成的前体溶液施加到基板上，形成金属氧化物薄膜。 将液体薄膜在空气中烘烤至高达500℃的温度，同时施加波长为180nm至300nm的UV辐射。 该薄膜可以在增加的温度下进行两次烘烤，同时在一个或两个烘烤处施加UV辐射。 然后将膜在约700℃至850℃的温度范围内退火，以产生薄膜固体金属氧化物产物。 或者，可以将UV辐射施加到液体前体，该薄膜可以在紫外辐射或UV辐射的这种应用的组合与前体之间或在烘烤之前或之后对薄膜进行退火，和/或UV退火 使用。 使用紫外线辐射显着降低了最终金属氧化物的漏电流和碳杂质含量。

公开(公告)号：US5972428A

公开(公告)日：1999-10-26

申请号：US611414

申请日：1996-03-05

申请人： Shinichiro Hayashi ,  Larry D. McMillan ,  Masamichi Azuma ,  Carlos A. Paz de Araujo

发明人： Shinichiro Hayashi ,  Larry D. McMillan ,  Masamichi Azuma ,  Carlos A. Paz de Araujo

IPC分类号： H01L21/314 ,  H01L21/316 ,  C23C16/00 ,  B05D1/02

CPC分类号： H01L21/31691

摘要： A liquid primer is misted, flowed into a deposition chamber and deposited on a substrate. A liquid precursor is then misted, flowed into a deposition chamber and deposited on the substrate. The primer and precursor are dried to form a solid thin film, which is then annealed to form a part of an electronic component in an integrated circuit, such as the dielectric in a memory cell. The primer is a solvent, and the precursor includes a metal carboxylate, a metal alkoxide, or a metal alkoxycarboxylate in a precursor solvent. Preferably, the primer and the precursor solvent are the same solvent, such as 2-methoxyethanol, xylenes, or n-butyl acetate.

摘要翻译： 液体底漆被雾化，流入沉积室并沉积在基底上。 然后液体前体被雾化，流入沉积室并沉积在基底上。 将底漆和前体干燥以形成固体薄膜，然后将其退火以形成集成电路中的电子部件的一部分，例如存储单元中的电介质。 引物是溶剂，前体在前体溶剂中包括金属羧酸盐，金属醇盐或烷氧基羧酸金属盐。 优选地，底漆和前体溶剂是相同的溶剂，例如2-甲氧基乙醇，二甲苯或乙酸正丁酯。

公开(公告)号：US5814849A

公开(公告)日：1998-09-29

申请号：US788229

申请日：1997-01-27

申请人： Masamichi Azuma ,  Carlos A. Paz De Araujo ,  Michael C. Scott

发明人： Masamichi Azuma ,  Carlos A. Paz De Araujo ,  Michael C. Scott

IPC分类号： C23C16/44 ,  C23C16/448 ,  C23C16/455 ,  C23C16/46 ,  C23C16/48 ,  C23C16/52 ,  C23C18/12 ,  C23C18/14 ,  C30B7/00 ,  H01C7/10 ,  H01L21/02 ,  H01L21/314 ,  H01L21/316 ,  H01L27/108 ,  H01L27/115 ,  H01L29/76

CPC分类号： C04B35/4682 ,  C04B35/47 ,  C04B35/6264 ,  C23C16/4412 ,  C23C16/448 ,  C23C16/4486 ,  C23C16/45561 ,  C23C16/4558 ,  C23C16/46 ,  C23C16/482 ,  C23C16/52 ,  C23C18/1216 ,  C23C18/1275 ,  C23C18/1295 ,  C23C18/14 ,  C30B29/68 ,  C30B7/00 ,  H01C7/1013 ,  H01L21/314 ,  H01L21/31691 ,  H01L27/10805 ,  H01L27/11502 ,  H01L28/56 ,  H01L28/60 ,  C04B2235/32 ,  C04B2235/3201 ,  C04B2235/3203 ,  C04B2235/3206 ,  C04B2235/3208 ,  C04B2235/3213 ,  C04B2235/3217 ,  C04B2235/3224 ,  C04B2235/3227 ,  C04B2235/3229 ,  C04B2235/3234 ,  C04B2235/3241 ,  C04B2235/3243 ,  C04B2235/3251 ,  C04B2235/3262 ,  C04B2235/3268 ,  C04B2235/3272 ,  C04B2235/3275 ,  C04B2235/3279 ,  C04B2235/3281 ,  C04B2235/3284 ,  C04B2235/3289 ,  C04B2235/441 ,  C04B2235/449 ,  C04B2235/6585 ,  C04B2235/72 ,  C04B2235/79 ,  H01L28/55

摘要： A method for fabricating an integrated circuit capacitor having a dielectric layer comprising BST with excess B-site material, such as titanium, added. A polyoxyalkylated metal liquid precursor solution is prepared comprising a stock solution of BST of greater then 99.999% purity blended with excess B-site material such as titanium such that the titanium is in the range of 0-100 mol %. A xylene exchange is then performed to adjust the viscosity of the solution for spin-on application to a substrate. The precursor is spun on a first electrode, dried at 400.degree. C. for 2 minutes, then annealed at 650.degree. C. to 800.degree. C. for about an hour to form a layer of BST with excess titanium. A second electrode is deposited, patterned, and annealed at between 650.degree. C. to 800.degree. C. for about 30 minutes. The resultant capacitor exhibits an enlarged dielectric constant with only a small increase in leakage current.

摘要翻译： 一种制造集成电路电容器的方法，该集成电路电容器具有包含BST的介电层，该BST具有过量的B位材料，例如钛。 制备聚氧化烷基化金属液体前体溶液，其包含与过量的B位材料如钛混合的大于99.999％纯度的BST的储备溶液，使得钛在0-100摩尔％的范围内。 然后进行二甲苯交换以调节溶液的粘度，以便旋涂到基底上。 将前体在第一电极上旋转，在400℃下干燥2分钟，然后在650℃至800℃退火约1小时，以形成具有过量钛的BST层。 在650℃至800℃下沉积，图案化和退火第二电极约30分钟。 所得到的电容器的介电常数增大，泄漏电流只有小的增加。

公开(公告)号：US5690727A

公开(公告)日：1997-11-25

申请号：US789469

申请日：1997-01-27

申请人： Masamichi Azuma ,  Carlos A. Paz de Araujo ,  Michael C. Scott

发明人： Masamichi Azuma ,  Carlos A. Paz de Araujo ,  Michael C. Scott

IPC分类号： C23C16/44 ,  C23C16/448 ,  C23C16/455 ,  C23C16/46 ,  C23C16/48 ,  C23C16/52 ,  C23C18/12 ,  C23C18/14 ,  C30B7/00 ,  H01C7/10 ,  H01L21/02 ,  H01L21/314 ,  H01L21/316 ,  H01L27/108 ,  H01L27/115 ,  C04B35/46 ,  C07F3/00 ,  C07F7/28

CPC分类号： C04B35/4682 ,  C04B35/47 ,  C04B35/6264 ,  C23C16/4412 ,  C23C16/448 ,  C23C16/4486 ,  C23C16/45561 ,  C23C16/4558 ,  C23C16/46 ,  C23C16/482 ,  C23C16/52 ,  C23C18/1216 ,  C23C18/1275 ,  C23C18/1295 ,  C23C18/14 ,  C30B29/68 ,  C30B7/00 ,  H01C7/1013 ,  H01L21/314 ,  H01L21/31691 ,  H01L27/10805 ,  H01L27/11502 ,  H01L28/56 ,  H01L28/60 ,  C04B2235/32 ,  C04B2235/3201 ,  C04B2235/3203 ,  C04B2235/3206 ,  C04B2235/3208 ,  C04B2235/3213 ,  C04B2235/3217 ,  C04B2235/3224 ,  C04B2235/3227 ,  C04B2235/3229 ,  C04B2235/3234 ,  C04B2235/3241 ,  C04B2235/3243 ,  C04B2235/3251 ,  C04B2235/3262 ,  C04B2235/3268 ,  C04B2235/3272 ,  C04B2235/3275 ,  C04B2235/3279 ,  C04B2235/3281 ,  C04B2235/3284 ,  C04B2235/3289 ,  C04B2235/441 ,  C04B2235/449 ,  C04B2235/6585 ,  C04B2235/72 ,  C04B2235/79 ,  H01L28/55

摘要： A method for fabricating an integrated circuit capacitor having a dielectric layer comprising BST with excess B-site material, such as titanium, added. A polyoxyalkylated metal liquid precursor solution is prepared comprising a stock solution of BST of greater then 99.999% purity blended with excess B-site material such as titanium such that the titanium is in the range of 0-100 mol %. A xylene exchange is then performed to adjust the viscosity of the solution for spin-on application to a substrate. The precursor is spun on a first electrode, dried at 400.degree. C. for 2 minutes, then annealed at 650.degree. C. to 800.degree. C. for about an hour to form a layer of BST with excess titanium. A second electrode is deposited, patterned, and annealed at between 650.degree. C. to 800.degree. C. for about 30 minutes. The resultant capacitor exhibits an enlarged dielectric constant with only a small increase in leakage current.

摘要翻译： 一种制造集成电路电容器的方法，该集成电路电容器具有包含BST的介电层，该BST具有过量的B位材料，例如钛。 制备聚氧化烷基化金属液体前体溶液，其包含与过量的B位材料如钛混合的大于99.999％纯度的BST的储备溶液，使得钛在0-100摩尔％的范围内。 然后进行二甲苯交换以调节溶液的粘度，以便旋涂到基底上。 将前体在第一电极上旋转，在400℃下干燥2分钟，然后在650℃至800℃退火约1小时，以形成具有过量钛的BST层。 在650℃至800℃下沉积，图案化和退火第二电极约30分钟。 所得到的电容器的介电常数增大，泄漏电流只有小的增加。

公开(公告)号：US06285048B1

公开(公告)日：2001-09-04

申请号：US08165082

申请日：1993-12-10

申请人： Masamichi Azuma ,  Michael C. Scott ,  Carlos A. Paz de Araujo ,  Joseph D. Cuchiaro

发明人： Masamichi Azuma ,  Michael C. Scott ,  Carlos A. Paz de Araujo ,  Joseph D. Cuchiaro

IPC分类号： H01L31072

CPC分类号： C04B35/4682 ,  C04B35/6264 ,  C04B2235/3213 ,  C04B2235/3224 ,  C04B2235/3227 ,  C04B2235/3229 ,  C04B2235/3243 ,  C04B2235/3268 ,  C04B2235/441 ,  C04B2235/449 ,  C04B2235/72 ,  C23C16/4412 ,  C23C16/448 ,  C23C16/4486 ,  C23C16/45561 ,  C23C16/4558 ,  C23C16/46 ,  C23C16/482 ,  C23C16/52 ,  C23C18/1216 ,  C23C18/1275 ,  C23C18/14 ,  C30B7/00 ,  C30B29/68 ,  H01C7/1013 ,  H01L21/314 ,  H01L21/31691 ,  H01L27/10805 ,  H01L27/11502 ,  H01L28/55 ,  H01L28/56 ,  H01L28/60

摘要： Integrated circuit capacitors in which the capacitor dielectric is a thin film of BST having a grain size smaller than 2000 Å. Typical gain sizes are 40 nanometers and less. The BST is formed by deposition of a liquid precursor by a spin-on process. The original liquid precursor includes an alkoxycarboxylate dissolved in 2-methoxyethanol and an xylene exchange is preformed just prior to spinning. The precursor is dried in air at a temperature of about 400° C. and then furnace annealed in oxygen at a temperature of between 675° C. and 850° C.

摘要翻译： 集成电路电容器，其中电容器电介质是具有小于2000埃的晶粒尺寸的BST薄膜。 典型的增益尺寸为40纳米以下。 BST通过旋涂工艺沉积液体前体而形成。 原始液体前体包括溶解在2-甲氧基乙醇中的烷氧基羧酸酯，并且在旋转之前预先形成二甲苯交换。 前体在空气中在约400℃的温度下干燥，然后在675℃至850℃的温度下在氧气中进行炉退火。

公开(公告)号：US5962085A

公开(公告)日：1999-10-05

申请号：US610330

申请日：1996-03-04

申请人： Shinichiro Hayashi ,  Larry D. McMillan ,  Masamichi Azuma ,  Carlos A. Paz de Araujo

发明人： Shinichiro Hayashi ,  Larry D. McMillan ,  Masamichi Azuma ,  Carlos A. Paz de Araujo

IPC分类号： B05D1/00 ,  B05D3/04 ,  B05D3/06 ,  B05D7/24 ,  C23C8/10 ,  C23C16/44 ,  C23C16/448 ,  C23C16/455 ,  C23C16/46 ,  C23C16/48 ,  C23C16/52 ,  C23C18/12 ,  C23C18/14 ,  C23C26/02 ,  C30B7/00 ,  H01L21/02 ,  H01L21/31 ,  H01L21/314 ,  H01L21/316 ,  H01L27/115 ,  H01L39/24 ,  H01L41/24 ,  H05K3/10 ,  C23C8/00

CPC分类号： H01L21/02197 ,  B05D1/00 ,  B05D1/60 ,  B05D3/0493 ,  B05D3/062 ,  B05D3/065 ,  C23C16/4412 ,  C23C16/4486 ,  C23C16/45561 ,  C23C16/4558 ,  C23C16/46 ,  C23C16/482 ,  C23C16/52 ,  C23C18/12 ,  C23C18/1216 ,  C23C18/1287 ,  C23C18/14 ,  C23C26/02 ,  C23C8/10 ,  C30B29/68 ,  C30B7/00 ,  C30B7/005 ,  H01L21/02282 ,  H01L21/31691 ,  H01L27/11502 ,  H01L28/56 ,  H01L28/60 ,  H01L41/314 ,  H01L28/55 ,  H01L41/1871 ,  H05K3/105

摘要： A substrate is located within a deposition chamber, the substrate defining a substrate plane. A barrier plate is disposed in spaced relation above the substrate and substantially parallel thereto, the area of said barrier plate in a plane parallel to said substrate being substantially equal to said area of said substrate in said substrate plane, i.e. within 10% of said substrate area. The barrier plate has a smoothness tolerance of 5% of the average distance between said barrier plate and said substrate. A mist is generated, allowed to settle in a buffer chamber, filtered through a 1 micron filter, and flowed into the deposition chamber between the substrate and barrier plate to deposit a liquid layer on the substrate. The liquid is dried to form a thin film of solid material on the substrate, which is then incorporated into an electrical component of an integrated circuit.

摘要翻译： 衬底位于沉积室内，衬底限定衬底平面。 阻挡板以与衬底相对的基本平行的方式设置成隔开关系，所述阻挡板在平行于所述衬底的平面中的面积基本上等于所述衬底平面中所述衬底的所述面积，即在所述衬底的10％内 区。 阻挡板具有所述阻挡板和所述基板之间的平均距离的5％的平滑度公差。 产生雾，允许沉淀在缓冲室中，通过1微米过滤器过滤，并流入基板和阻挡板之间的沉积室，以在基板上沉积液体层。 将液体干燥以在基板上形成固体材料的薄膜，然后将其并入集成电路的电气部件中。

公开(公告)号：US5920574A

公开(公告)日：1999-07-06

申请号：US932894

申请日：1997-09-18

申请人： Yasuhiro Shimada ,  Keisaku Nakao ,  Atsuo Inoue ,  Masamichi Azuma ,  Eiji Fujii

发明人： Yasuhiro Shimada ,  Keisaku Nakao ,  Atsuo Inoue ,  Masamichi Azuma ,  Eiji Fujii

IPC分类号： G01R31/26 ,  G01R31/28 ,  G01R31/30 ,  G11C11/22 ,  G11C29/50 ,  G11C29/56 ,  H01L21/66 ,  H01L21/822 ,  H01L21/8242 ,  H01L27/04 ,  H01L27/10 ,  H01L27/108 ,  G11C29/00 ,  G01R1/04

CPC分类号： G11C29/50016 ,  G11C29/50 ,  G11C11/22 ,  G11C2029/5002

摘要： A method for an accelerated test of semiconductor devices comprises the steps of determining a relational expression t.sub.1 =t.sub.2.sup.m between an information holding lifetime t.sub.1 at a temperature T.sub.1 and another lifetime t.sub.2 at another temperature T.sub.2, expressing the exponent m as a function of the temperature that is proportional to the Boltzmann's factor, and calculating the information holding lifetime t.sub.2 at the temperature T.sub.2 on the basis of the information holding lifetime t.sub.1 at the temperature T.sub.1 using the relational expression.

摘要翻译： 一种用于半导体器件的加速测试的方法包括以下步骤：确定在温度T1下的信息保持寿命t1和在另一温度T2的另一寿命t2之间的关系表达式t1 = t2m，其表示作为温度的函数的指数m 与玻耳兹曼因子成正比，并且使用关系式，基于温度T1下的信息保持寿命t1计算温度T2下的信息保持期限t2。