1. A method for fabricating a semiconductor structure in a substrate, the method comprising the steps of:
disposing at least one strained region on the substrate, thereby defining an interface therebetween, the at least one strained region having a distal zone away from the interface and having an intermediate zone between the interface and the distal zone;
disposing a gate dielectric proximate the distal zone; and
disposing a gate electrode proximate the gate dielectric;
wherein the substrate, the interface, the at least one strained region, the gate dielectric, and the gate electrode are characterized at least in part by an impurity gradient, the impurity gradient having a value substantially equal to zero in the distal zone and having an increasing value in the intermediate zone in a direction from the distal zone to the interface, the impurity gradient describing a concentration of Ge.
2. A method for fabricating a semiconductor device, the method comprising the steps of:
defining at least one strained region, the at least one strained region having a distal zone and a proximal zone;
forming a gate dielectric proximate the distal zone; and
forming a gate electrode proximate the gate dielectric;
wherein the at least one strained region, the gate dielectric, and the gate electrode are characterized at least in part by an impurity gradient, the impurity gradient having a value in the distal zone sufficiently low to avoid degradation of device performance and having an increasing value in the proximal zone in a direction extending away from the distal zone, the impurity gradient describing a concentration of Ge.
3. A method for fabricating a semiconductor device, the method comprising the steps of:
defining at least one strained region, the at least one strained region having a distal zone;
forming a gate dielectric proximate the distal zone;
forming a gate electrode proximate the gate dielectric; and
forming at least one strain-inducing material proximate the at least one strained region;
wherein the at least one strained region and the at least one strain-inducing material are characterized at least in part by an impurity gradient describing a concentration of an impurity as a function of location in the device, the impurity concentration has a first value substantially equal to zero in the distal zone and a second value that increases in a direction extending away from the distal zone in a zone between the distal zone and the strain-inducing material, and the impurity comprises Ge.
4. The method of claim 3, wherein the at least one strained region and the at least one strain-inducing material are disposed over a substrate.
5. The method of claim 4, wherein the substrate consists essentially of Si.
6. The method of claim 4, wherein the substrate comprises a buried insulating layer.
7. The method of claim 3, wherein the gate dielectric has a dielectric constant greater than that of SiO2 and comprises Hf.
8. The method of claim 3, wherein the at least one strain-inducing material comprises SiGe.
9. The method of claim 8, wherein the at least one strain-inducing material is at least partially relaxed.
10. The method of claim 3, wherein the at least one strained region comprises Si.
11. The method of claim 10, wherein the at least one strained region consists essentially of Si.
12. The method of claim 3, wherein the impurity concentration has a value substantially equal to zero in the gate dielectric.
13. The method of claim 3, further comprising forming an isolation region, wherein the isolation region is disposed proximate the at least one strain-inducing material.
14. The method of claim 3, wherein strain in the at least one strained region is induced by lattice mismatch between the at least one strained region and the at least one strain-inducing material.
15. The method of claim 3, wherein the gate electrode comprises a metal.
16. The method of claim 3, wherein the gate electrode comprises polysilicon.
17. The method of claim 1, further comprising forming a source region and a drain region in the substrate prior to defining the at least one strained region.
18. The method of claim 2, further comprising forming a source region and a drain region in the substrate prior to defining the at least one strained region.
19. The method of claim 3, further comprising forming a source region and a drain region prior to defining the at least one strained region.
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. An image forming apparatus comprising:
a plurality of image forming units, one image forming unit being provided for each of a plurality of colors, and forming an image of the respective corresponding color;
a patch forming unit, which actuates the respective image forming units according to image forming conditions for the respective colors of the image forming units to form density detection patches of the respective colors;
a density detecting unit that detects a density of the density detecting patches;
a condition correcting unit that controls the density detecting unit to detect the density of the density detecting patches of the respective colors, and corrects the image forming conditions based on respective deviations between the detected densities of the density detecting patches of the respective colors and target densities defined for each of the colors;
a patch re-forming unit that, for each color for which the respective deviation is greater than a threshold value, actuates the image forming unit corresponding to the color so as to generate a re-formed density detecting patch of the color using the respective image forming condition previously corrected by the condition correcting unit; and
a condition re-correcting unit that is configured to control the density detecting unit to detect a density of the re-formed density detecting patch and re-correct the respective image forming condition of the color of the re-formed density detecting path based on a deviation between the density of the re-formed density detecting patch and the target density of the color corresponding to the re-formed density detecting patch.
2. The image forming apparatus according to claim 1, further comprising:
a preparation process unit that executes a preparation process to prepare for detection of the density by the density detecting unit before the density detecting patch is formed by the patch forming unit; and
a preparation process re-executing unit that re-executes the preparation process before the re-formed density detecting patch is generated by the patch re-forming unit.
3. The image forming apparatus according to claim 2, further comprising:
a cleaning unit that cleans the density detecting patch formed by the patch forming unit,
wherein the preparation process re-executing unit executes the preparation process at a same time that the density detecting patch is cleaned by the cleaning unit.
4. The image forming apparatus according to claim 2, further comprising:
a base member, on which the density detecting patches are formed,
wherein the density detecting unit comprises:
a light emitting element; and
a light receiving element that receives light, which is emitted from the light emitting element and is reflected from a surface of the density detecting patch or a surface of the base member, and wherein the preparation process comprises:
receiving the light reflected from the surface of the density detecting patch or the surface of the base member by the light receiving element; and
detecting an amount of the received light.
5. The image forming apparatus according to claim 4,
wherein the preparation process further comprises:
a light amount adjustment process comprising adjusting an amount of the light emitted from the light emitting element so that the amount of the detected light becomes constant.
6. The image forming apparatus according to claim 1,
wherein the patch forming unit forms the density detecting patches of the respective colors in a straight line with a fixed pitch while being arranged in a given order, and
wherein the patch re-forming unit generates the re-formed density detecting patches in a straight line with a fixed pitch while being arranged in the given order.
7. The image forming apparatus according to claim 1,
wherein each of the image forming units comprises:
an image carrier on which an electrostatic latent image is formed; and
a developing member, to which development bias is applied, and which supplies developer to the image carrier according to the development bias, and
wherein the image forming condition of the respective image forming unit is the development bias.
8. An image forming apparatus comprising:
a plurality of image forming units, each of which forms an image in a respective one of a plurality of colors;
a density sensor;
a patch forming unit, which individually controls each of the image forming units according to an image forming condition associated with the respective color of the respective image forming unit to form a patch of the respective color;
a condition setting unit that controls the density sensor to detect the density of a patch, calculates a deviation between the detected density of the patch and a target density defined for the respective color, and corrects the image forming condition associated with the color of the patch based on the calculated deviation;
a controller that controls the patch forming unit to generate a patch for each of the plurality of colors and controls the condition setting unit to detect the densities of the respective patches, calculate the respective deviations, and to correct the respective image forming conditions associated with each of the plurality of colors, and
for each color for which the respective deviation is greater than a threshold value associated with the respective color, controls the patch forming unit to regenerate the patch for the color using the corrected image forming condition, and controls the condition setting unit to detect the density of the regenerated patch, recalculate the deviation, and re-correct the image forming condition associated with the color of the regenerated patch.
9. The image forming apparatus according to claim 8, wherein the patch forming unit generates the patches for each of the plurality of colors in a straight line with a fixed pitch while being arranged in a given order.
10. The image forming apparatus according to claim 8, further comprising a conveyor belt, on which the patches are formed.
11. A method for adjusting color densities in an image forming apparatus comprising a density sensor and a plurality of image forming units, each image forming unit being associated with a respective one of a plurality of colors, the method comprising:
individually controlling each of the image forming units according to an image forming condition associated with the respective color of the respective image forming unit to form a patch of each of the plurality of colors;
detecting a density of each of the patches;
calculating a deviation between the detected density of each of the patches and a target density defined for the respective color;
correcting the respective image forming conditions associated with each of the plurality of colors based on the calculated deviations;
comparing the respective deviation for each color with a threshold deviation associated with the color, and
for each color for which the respective deviation is greater than the threshold deviation,
regenerating the patch for the color using the corrected image forming condition;
detecting a density of the regenerated patch;
calculating a second deviation between the density of the regenerated patch and the target density associated with the color; and
re-correcting the image forming condition associated with the color based on the calculated second deviation.