What is claimed is:
1. A semiconductor memory comprising:
a memory cell array;
a signal generation circuit configured to generate an internal address signal used for selecting rows of the memory cell array when a refresh operation is executed; and
a control circuit configured to fix a value of at least one of bits of the internal address signal based on a first control signal and to select the rows in a refresh area whose memory capacity is smaller than that of the memory cell array, when the refresh operation is executed.
2. The semiconductor memory according to claim 1, wherein values of n significant bits of the internal address signal are fixed when the refresh area has a memory capacity which is n of the memory capacity of the memory cell array.
3. The semiconductor memory according to claim 1, wherein intervals at which the rows in the refresh area are selected are made 2n times longer, when the refresh area has a memory capacity which is n of the memory capacity of the memory cell array.
4. The semiconductor memory according to claim 1, wherein said refresh area is predetermined based on data stored in a memory element of a chip.
5. The semiconductor memory according to claim 1, wherein a function of selecting only the rows in the refresh area is made effective in response to a second control signal.
6. The semiconductor memory according to claim 1, wherein one of two modes is selected when the refresh operation is executed, said two modes including a mode in which all rows of the memory cell array are selected based on the first control signal, and a mode in which only the rows in the refresh area are selected.
7. The semiconductor memory according to claim 1, wherein said first control signal is generated outside of a chip.
8. The semiconductor memory according to claim 1, wherein said first control signal is generated inside of a chip.
9. The semiconductor memory according to claim 1, wherein said semiconductor memory is used in a portable electronic device.
10. The semiconductor memory according to claim 1, which is a dynamic random access memory.
11. A semiconductor memory device comprising:
a memory cell array;
a signal generation circuit configured to generate an internal address signal used for selecting rows of the memory cell array when a refresh operation is executed;
a control circuit configured to select the rows in a refresh area whose memory capacity is smaller than that of the memory cell array, when the refresh operation is executed; and
a refresh timer configured to determine refresh execution timings,
wherein, when the rows in the refresh area are selected, the refresh timer switches the refresh execution timings and changes timings for selecting the rows in the refresh area.
12. The semiconductor memory according to claim 11, wherein values of n significant bits of the internal address signal are fixed when the refresh area has a memory capacity which is n of the memory capacity of the memory cell array.
13. The semiconductor memory according to claim 11, wherein intervals at which the rows in the refresh area are selected are made 2n times longer, when the refresh area has a memory capacity which is n of the memory capacity of the memory cell array.
14. The semiconductor memory according to claim 11, wherein said refresh area is predetermined based on data stored in a memory element of a chip.
15. The semiconductor memory according to claim 11, wherein a function of selecting only the rows in the refresh area is made effective in response to a second control signal.
16. The semiconductor memory according to claim 11, wherein one of two modes is selected when the refresh operation is executed, said two modes including a mode in which all rows of the memory cell array are selected based on the first control signal, and a mode in which only the rows in the refresh area are selected.
17. The semiconductor memory according to claim 11, wherein said first control signal is generated outside of a chip.
18. The semiconductor memory according to claim 11, wherein said first control signal is generated inside of a chip.
19. The semiconductor memory according to claim 11, wherein said semiconductor memory is used in a portable electronic device.
20. The semiconductor memory according to claim 11, which is a dynamic random access memory.
21. A semiconductor memory comprising:
a memory cell array;
a signal generation circuit configured to generate an internal address signal used for selecting rows of the memory cell array when a refresh operation is executed;
a control circuit configured to fix a value of at least one of bits of the internal address signal based on a first control signal and to select the rows in a refresh area whose memory capacity is smaller than that of the memory cell array, when the refresh operation is executed; and
a refresh timer configured to determine refresh execution timings,
wherein, when the rows in the refresh area are selected, the refresh timer switches the refresh execution timings and changes timings for selecting the rows in the refresh area.
22. The semiconductor memory according to claim 21, wherein values of n significant bits of the internal address signal are fixed when the refresh area has a memory capacity which is n of the memory capacity of the memory cell array.
23. The semiconductor memory according to claim 21, wherein intervals at which the rows in the refresh area are selected are made 2n times longer, when the refresh area has a memory capacity which is n of the memory capacity of the memory cell array.
24. The semiconductor memory according to claim 21, wherein said refresh area is predetermined based on data stored in a memory element of a chip.
25. The semiconductor memory according to claim 21, wherein a function of selecting only the rows in the refresh area is made effective in response to a second control signal.
26. The semiconductor memory according to claim 21, wherein one of two modes is selected when the refresh operation is executed, said two modes including a mode in which all rows of the memory cell array are selected based on the first control signal, and a mode in which only the rows in the refresh area are selected.
27. The semiconductor memory according to claim 21, wherein said first control signal is generated outside of a chip.
28. The semiconductor memory according to claim 21, wherein said first control signal is generated inside of a chip.
29. The semiconductor memory according to claim 21, wherein said semiconductor memory is used in a portable electronic device.
30. The semiconductor memory according to claim 21, which is a dynamic random access memory.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A measuring apparatus comprising:
a heating unit for applying heat to a first point in selected one of layers formed in a workpiece and propagating the heat to a second point of the workpiece;
a measuring unit for measuring a displacement of the workpiece at the second point to which the heat has been propagated; and
an analyzing unit for analyzing an internal structure of the workpiece based on the displacement measured by said measuring unit in consideration of a distance between the first point and the second point.
2. The measuring apparatus according to claim 1, wherein said heating unit utilizes a frequency-modulated laser beam to apply heat to the first point.
3. The measuring apparatus according to claim 2, wherein said measuring unit measures a reflected laser beam which is reflected from the workpiece,
wherein said analyzing unit is configured to extract an amplitude in synchronism with a modulation frequency of the frequency-modulated laser beam from the reflected laser beam.
4. The measuring apparatus according to claim 2, wherein the frequency-modulated laser beam is varied in modulation frequency,
wherein said analyzing unit outputs information of the workpiece along its depth.
5. A measuring apparatus comprising:
a strain applying unit for applying a strain to a first point in selected one of layers formed in a workpiece and propagating the strain to a second point of the workpiece;
a measuring unit for measuring a displacement of the workpiece at the second point to which the strain has been propagated; and
an analyzing unit for analyzing an internal structure of the workpiece based on the displacement measured by said measuring unit in consideration of a distance between the first point and the second point.
6. The measuring apparatus according to claim 5, wherein said strain applying unit utilizes a frequency-modulated wave to apply the strain to the first point.
7. The measuring apparatus according to claim 6, wherein said strain applying unit utilizes a sound wave to apply the strain to the first point.
8. The measuring apparatus according to claim 6, wherein said strain applying unit utilizes an ultrasonic wave to apply the strain to the first point.
9. The measuring apparatus according to claim 6, wherein said strain applying unit utilizes an electromagnetic wave to apply the strain to the first point.
10. The measuring apparatus according to claim 6, wherein said measuring unit measures a reflected wave which is reflected from the workpiece,
wherein said analyzing unit is configured to extract an amplitude in synchronism with a modulation frequency of the frequency-modulated wave from the reflected wave.
11. The measuring apparatus according to claim 6, wherein the frequency-modulated wave is varied in modulation frequency, wherein said analyzing unit outputs information of the workpiece along its depth.
12. A polishing apparatus comprising:
a polishing table having a polishing surface;
a top ring for holding and pressing a workpiece to be polished against said polishing surface; and
a measuring apparatus for measuring the thickness of layers formed in the workpiece, said measuring apparatus comprising:
a heating unit for applying heat to a first point in selected one of the layers formed in the workpiece and propagating the heat to a second point of the workpiece;
a measuring unit for measuring a displacement of the workpiece at the second point to which the heat has been propagated; and
an analyzing unit for analyzing an internal structure of the workpiece based on the displacement measured by said measuring unit in consideration of a distance between the first point and the second point.
13. The polishing apparatus according to claim 12, wherein said heating unit utilizes a frequency-modulated laser beam to apply heat to the first point.
14. The polishing apparatus according to claim 13, wherein said measuring unit measures a reflected laser beam which is reflected from the workpiece,
wherein said analyzing unit is configured to extract an amplitude in synchronism with a modulation frequency of the frequency-modulated laser beam from the reflected laser beam.
15. The polishing apparatus according to claim 13, wherein the frequency-modulated laser beam is varied in modulation frequency,
wherein said analyzing unit outputs information of the workpiece along its depth.
16. A polishing apparatus comprising:
a polishing table having a polishing surface;
a top ring for holding and pressing a workpiece to be polished against said polishing surface; and
a measuring apparatus for measuring the thickness of layers formed in the workpiece, said measuring apparatus comprising:
a strain applying unit for applying a strain to a first point in selected one of the layers formed in the workpiece and propagating the strain to a second point of the workpiece;
a measuring unit for measuring a displacement of the workpiece at the second point to which the strain has been propagated; and
an analyzing unit for analyzing an internal structure of the workpiece based on the displacement measured by said measuring unit in consideration of a distance between the first point and the second point.
17. The polishing apparatus according to claim 16, wherein said strain applying unit utilizes a frequency-modulated wave to apply the strain to the first point.
18. The polishing apparatus according to claim 17, wherein said strain applying unit utilizes a sound wave to apply the strain to the first point.
19. The polishing apparatus according to claim 17, wherein said strain applying unit utilizes an ultrasonic wave to apply the strain to the first point.
20. The polishing apparatus according to claim 17, wherein said strain applying unit utilizes an electromagnetic wave to apply the strain to the first point.
21. The polishing apparatus according to claim 17, wherein said measuring unit measures a reflected wave which is reflected from the workpiece,
wherein said analyzing unit is configured to extract an amplitude in synchronism with a modulation frequency of the frequency-modulated wave from the reflected wave.
22. The polishing apparatus according to claim 17, wherein the frequency-modulated wave is varied in modulation frequency,
wherein said analyzing unit outputs information of the workpiece along its depth.