What is claimed is:
1. A semiconductor device comprising:
a bit line for transferring a signal changing between a first voltage and a second voltage higher than said first voltage;
a memory cell having an element for storing information and a selection gate for connecting said element to said bit line when selected, said selection gate being constituted of an insulated gate type field effect transistor;
a word line connected to the selection gate of said memory cell, for transferring a voltage determining selection and unselection of said element; and
word line voltage applying circuitry for applying said voltage to said word line, said word line voltage applying circuitry applying a third voltage outside a voltage changing range of said bit line when said element is unselected, and applying a fourth voltage when said element is selected, said third voltage being at a level for setting a reliability evaluation value of a gate insulating film of said selection gate to, at most, a reliability evaluation value of the gate insulating film when said fourth voltage is applied.
2. The semiconductor device according to claim 1, wherein
said third voltage is a negative voltage, and said first voltage is at a level of externally applied ground voltage.
3. The semiconductor device according to claim 1, wherein
said word line voltage applying circuitry includes a screening circuit for accelerating stress of the gate insulating film of said selection gate in an unselected state.
4. The semiconductor device according to claim 1, wherein
said word line voltage applying circuitry comprises a circuit for accelerating an electric field applied the gate insulating film of said selection gate in a selected state, and a circuit for accelerating the electric field applied to the gate insulating film of said selection gage in an unselected state.
5. The semiconductor device according to claim 1, wherein
said third voltage is at a level of externally applied ground voltage, and said first voltage is at a level higher than said third voltage.
6. The semiconductor device according to claim 1, wherein
said third voltage is a voltage lower than said first voltage, and said fourth voltage is a voltage higher than said second voltage.
7. A semiconductor device comprising:
an internal circuitry having a power source node;
a power line transmitting a power source voltage;
a power supply control transistor formed of an insulated gate type field effect transistor, coupled between said power source node and said power line, set to a high impedance state when said internal circuitry is in an unselected state, and set to a low impedance state when said internal circuitry is in a selected state; and
control circuitry for applying a control signal to a gate of said power supply control transistor in response to an operation mode designation signal designating an operation mode of said internal circuitry, said control circuitry applying, as said control signal, a voltage for making a reliability evaluation value of a gate insulating film of said power supply control transistor in a high impedance state be not greater than a reliability evaluation value of the gate insulating film in said low impedance state.
8. The semiconductor device according to claim 7, wherein
said control circuitry sets said control signal to a voltage level higher in absolute value than the power source voltage on said power line when said power supply control transistor is in a high impedance state.
9. The semiconductor device according to claim 7, wherein
said control circuitry includes a circuit for accelerating an electric field applied to a gate insulating film of said power supply control transistor when said power supply control transistor is in a high impedance state.
10. The semiconductor device according to claim 7, wherein
said power line transfers the power source voltage higher than a ground voltage, and said power supply control transistor is of a P channel type.
11. A semiconductor device comprising:
internal circuitry including a plurality of sub-circuits, said plurality of sub-circuits including a first sub-circuit connected to a first power line transferring a first power source voltage and a second sub-circuit connected to a second power line transferring a second power source voltage;
first power source circuitry connected to said first power line, for generating the first power source voltage, the first power source circuitry generating a second voltage larger in absolute value than a first voltage level generated in selection of said internal circuitry when said internal circuitry is unselected onto said power line as said first power source voltage; and
second power source circuitry connected to said second power line, for generating a voltage at the first voltage level as said second power source voltage independently of selection and unselection of said internal circuitry, a reliability evaluation value of a gate insulating film of a transistor of a sub-circuit of said internal circuitry in an unselected state being set, at most, to a reliability evaluation value of the gate insulating film of said internal circuit in a selected state.
12. The semiconductor device according to claim 11, wherein
said first power source circuitry includes a circuit for accelerating said first power source voltage generated when said internal circuitry is in an unselected state.
13. The semiconductor device according to claim 11, wherein
said second power source circuitry includes a circuit for accelerating said second power source voltage generated when said internal circuitry is in an unselected state.
14. The semiconductor device according to claim 11, further comprising:
a power source control transistor, formed of an insulated gate type transistor and connected between the first and second power lines, for electrically separating said first and second power lines when said internal circuitry is in an unselected state, a reliability evaluation value of a gate insulating film of said power source control transistor in the unselected state of the internal circuitry being set, at most, to a reliability evaluation value thereof in a selected state.
15. The semiconductor device according to claim 14, wherein
said power source control transistor receives a voltage larger in absolute value said first power source voltage at a gate thereof for connecting said first and second power lines together when said internal circuitry is in the selected state.
The claims below are in addition to those above.
All refrences to claims which appear below refer to the numbering after this setence.
1. A method for producing a biocompatible structure, comprising:
obtaining a load graph representing a functional relationship between a weight percentage of first tissue forming nanoparticles in a polymer film and a maximum load of that polymer film;
obtaining a stress graph representing a functional relationship between the weight percentage of the first tissue forming nanoparticles in a polymer film and maximum stress of that polymer film;
determining a first weight percentage corresponding to a peak of the load graph and determining a second weight percentage corresponding to a peak of the stress graph;
determining an optimal weight percentage based on the first and second weight percentage values;
preparing a polymer film having a polymer and the first tissue forming nanoparticles, wherein a weight percentage of the first tissue forming nanoparticles to the polymer in the polymer film is the determined optimal weight percentage;
dividing the polymer film into a plurality of strips;
constructing a scaffold by stacking the strips to form polymer layers and adding bone or composite particles between the polymer layers;
applying a second solution to the scaffold to form a coated scaffold; and
adding second tissue forming particles to the coated scaffold to form the biocompatible structure.
2. The method of claim 1, wherein the step of preparing the polymer film comprises:
dissolving the polymer in a solvent to form a first solution;
adding the first tissue forming nanoparticles to the first solution to form the second solution wherein a weight percentage of the first tissue forming nanoparticles to the polymer is the determined optimal weight percentage; and
applying the second solution to a surface to form a polymer film on the surface, wherein the first tissue forming nanoparticles are dispersed in the polymer film.
3. The method of claim 1, wherein the load graph has a first peak and a second peak; wherein a weight percentage corresponding to the second peak is larger than a weight percentage corresponding to the first peak; and wherein the first weight percentage is the weight percentage corresponding to the second peak.
4. The method of claim 1, wherein the stress graph has a first peak and a second peak; wherein a weight percentage corresponding to the second peak is larger than a weight percentage corresponding to the first peak; and wherein the second weight percentage is the weight percentage corresponding to the second peak.
5. The method of claim 1, further comprising:
determining an upper limit value of a range of the optimal weight percentage as a maximum value of the first weight percentage and the second weight percentage plus a first predetermined percentage;
determining a lower limit value of the range as a minimum value of the first weight percentage and the second weight percentage minus a second predetermined percentage; and
selecting a percentage from the range as the optimal weight percentage.
6. The method of claim 5, wherein each of the first and second predetermined percentages is about 5%.
7. The method of claim 5, wherein each of the first and second predetermined percentages is about 0%.
8. The method of claim 1, further comprising:
determining an upper limit value of a range of the optimal weight percentage as an average of the first weight percentage and the second weight percentage plus a third predetermined percentage;
determining a lower limit value of the range of the optimal weight percentage as the average minus a fourth predetermined percentage; and
selecting a percentage from the range as the optimal weight percentage.
9. The method of claim 8, wherein the third or the fourth predetermined percentage is about 5%.
10. The method of claim 8, wherein the third or the fourth predetermined percentage is about 0%.
11. The method of claim 1, wherein the optimal weight percentage is in a range from about 0% to about 30%.
12. The method of claim 11, wherein the optimal weight percentage is about 20%.
13. The method of claim 1, wherein polymers in the biocompatible polymer film comprise a synthetic biodegradable polymer, a biodegradable polymer from natural source, or a mixture thereof;
wherein the synthetic biodegradable polymer comprises polyurethane, polylactide (PLA), polyglycolide (PGA), poly(lactide-co-glycolide) (PLGA), poly(e-caprolactone), polydioxanone, polyanhydride, trimethylene carbonate, poly(\u03b2-hydroxybutyrate), poly(g-ethyl glutamate), poly(DTH iminocarbonate), poly(bisphenol A iminocarbonate), poly(ortho ester), polycyanoacrylate, polyphosphazene, or a mixture thereof; and
wherein the biodegradable polymer derived from natural source comprises modified polysaccharides, modified proteins, or a mixture thereof.
14. The method of claim 1, wherein the first tissue forming nanoparticles comprise nanoparticles of hydroxypatites, tricalcium phosphates, mixed calcium phosphates and calcium carbonate, bone particles of zenograft, bone particles of allografts, autografts, bone particles of alloplastic grafts, or a mixture thereof.
15. The method of claim 1, wherein the scaffold is formed by stacking the strips and layers of the second tissue forming particles alternatively.
16. The method of claim 1, further comprising plasma treating the biocompatible structure.
17. The method of claim 1, where the second tissue particles comprises nano-sized bone particles, micro-sized bone particles, or a mixture thereof.
18. The method of claim 1, further comprising adding a third tissue forming material to the biocompatible structure,
wherein the third tissue forming material comprises a bioactive material, cells, or a mixture thereof;
wherein the bioactive material comprises proteins, enzymes, growth factors, amino acids, bone morphogenic proteins, platelet derived growth factors, vascular endothelial growth factors, or a mixture thereof; and
wherein the cells comprises epithelial cells, neurons, glial cells, astrocytes, podocytes, mammary epithelial cells, islet cells, endothelial cells, mesenchymal cells, stem cells, osteoblast, muscle cells, striated muscle cells, fibroblasts, hepatocytes, ligament fibroblasts, tendon fibroblasts, chondrocytes, or a mixture thereof.
19. A method for producing a biocompatible structure, comprising:
obtaining a first graph representing a functional relationship between a weight percentage of first tissue forming nanoparticles in a polymer film and a first property of that polymer film;
obtaining a second graph representing a functional relationship between the weight percentage of the first tissue forming nanoparticles in a polymer film and a second property of that polymer film;
determining a first weight percentage corresponding to a peak of the first graph and determining a second weight percentage corresponding to a peak of the second graph;
determining an optimal weight percentage based on the first and second weight percentage values;
preparing a polymer film having a polymer and the first tissue forming nanoparticles, wherein a weight percentage of the first tissue forming nanoparticles to the polymer in the polymer film is the determined optimal weight percentage;
dividing the polymer film into a plurality of strips;
constructing a scaffold by stacking the strips to form polymer layers and adding bone or composite particles between the polymer layers;
applying the second solution to the scaffold to form a coated scaffold; and
adding the second tissue forming particles to the coated scaffold to form the biocompatible structure.
20. The method of claim 19, wherein the step of preparing the polymer film comprises:
dissolving the polymer in a solvent to form a first solution;
adding the first tissue forming nanoparticles to the first solution to form a second solution wherein a weight percentage of the first tissue forming nanoparticles to the polymer is the determined optimal weight percentage; and
applying the second solution to a surface to form a polymer film on the surface, wherein the first tissue forming nanoparticles are dispersed in the polymer film.
21. The method of claim 19,
wherein the first graph is a load graph representing a functional relationship between a weight percentage of tissue forming nanoparticles in a polymer film and a maximum load of that polymer film; and
wherein the second graph is a stress graph representing a functional relationship between the weight percentage of tissue forming nanoparticles in a polymer film and maximum stress of that polymer film.
22. The method of claim 19, further comprising determining an upper limit value and a lower limit value of the optimal weight percentage,
wherein the upper limit value is a maximum weight percentage of the first weight percentage and the second weight percentage plus a first predetermined percentage; and
wherein the lower limit value is a minimum weight percentage of the first weight percentage and the second weight percentage minus a second predetermined percentage.
23. The method of claim 22, wherein each of the first and second predetermined percentages is about 0%-10%.
24. The method of claim 19, wherein the optimal weight percentage is chosen from a range of an average of the first weight percentage and the second weight percentage plusminus a third predetermined percentage.
25. The method of claim 24, wherein the third predetermined percentages is about 0%-10%.
26. The method of claim 19, wherein the optimal weight percentage of the tissue forming nanoparticles in the polymer is about 20%.