1. A method of forming a field effect transistor (FET), comprising:
forming a channel layer with a semiconductor substrate;
forming a gate oxide layer on the channel layer;
forming a gate electrode material on the gate oxide layer;
forming a mask layer on the gate electrode material;
patterning the gate electrode material using the mask layer to form a gate electrode;
forming spacers;
etching the channel layer using the spacers as a mask for defining regions reserved for a source region and a drain region; and
forming an impurity-containing epitaxial layer in the defined regions to form the source and drain regions.
2. The method of claim 2, wherein the FET is a FinFET and the step of forming a channel layer comprises forming a protruded channel layer.
3. A method of forming a FinFET comprising:
providing a semiconductor substrate with a protrusion, the protrusion having a top surface and opposite side surfaces;
forming a layer on the protrusion;
patterning the layer to form a line pattern from the layer, the line pattern extending across the top surface of the protrusion;
removing a first portion of the protrusion on a first side of the line pattern at a first location;
removing a second portion of the protrusion on a second side of the line pattern at a second location, a remaining portion of the protrusion under the line pattern and defined by the removal of the first and second portions of the protrusion comprising a channel region of the FinFET;
eptitaxially growing a source region of the FinFET at the first location of the semiconductor substrate and a drain region of the FinFET at the second location of the semiconductor substrate, the channel region being interposed between the source region and the drain region.
4. The method of claim 3, further comprising:
implanting impurities into a first portion of the semiconductor substrate; and
forming the protrusion from the first portion.
5. The method of claim 3, wherein the first line pattern comprises a hard mask comprising an insulating material.
6. The method of claim 5, further comprising forming gate sidewall spacers.
7. The method of claim 6, wherein a junction of the source region and the channel region aligns with a first gate sidewall spacer and a junction of the drain region and the channel region aligns with a second gate sidewall spacer.
8. The method of claim 3, wherein the line pattern comprises a gate structure.
9. The method of claim 8, wherein the gate structure comprises a floating gate.
10. The method of claim 9, wherein the gate structure comprises a gate electrode.
11. The method of claim 3, wherein the line pattern is formed to extend from one of the opposite side surfaces of the protrusion to the other of the opposite side surfaces of the protrusion and across the top surface of the protrusion.
12. The method of claim 11, wherein the first line pattern comprises polysilicon.
13. The method of claim 3, further comprising:
etching a trench in the semiconductor substrate;
forming an insulating material in the trench; and
etching a top surface of the insulating material in the trench to expose the opposite side surfaces of the protrusion.
13. The method of claim 12, further comprising:
implanting impurities of the protrusion into the semiconductor substrate prior to etching the trench in the semiconductor substrate.
14. The method of claim 3, further comprising:
epitaxially growing the protrusion on the semiconductor substrate.
15. A method of forming a FinFET comprising:
forming a fin extending from a semiconductor substrate, the fin comprising a crystalline semiconductor material;
forming a gate structure including sidewall spacers;
removing first and second portions of the fin to respective first and second locations;
epitaxially growing a drain region of the FinFET at the first location of the semiconductor substrate and epitaxially growing a source region of the FinFET at the second location of the semiconductor substrate,
wherein a channel region of the FinFET is formed from the fin at a location under the gate structure and between the drain region and the source region.
16. The method of claim 15, wherein a junction of the source region and the channel region aligns with a first sidewall spacer of the gate structure and a junction of the drain region and the channel region aligns with a second sidewall spacer of the gate structure.
17. The method of claim 15, wherein the gate structure is formed before removing first and second portions of the fin.
18. The method of claim 15, wherein the gate structure comprises a gate electrode extending along side surfaces and a top surface of the channel region formed from the fin.
19. The method of claim 15, wherein the step of removing first and second portions of the fin comprises anisotropic etching.
20. The method of claim 15, wherein the drain region and source region are grown with impurities.
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 radio access network apparatus, comprising:
a first storage area and a second storage area different from the first storage area;
a receiver that receives, from a mobile station, a request signal comprising context information used to communicate with the mobile station and subsequently receives, from the mobile station, a completion signal that indicates that a connection with the mobile station is established;
a controller that controls storage of the context information in the first storage area in response to receiving the request signal and that controls storage of the context information in the second storage area in response to receiving the completion signal.
2. The radio access network apparatus according to claim 1, further comprising:
a transmitter that transmits, to the mobile station, a setup signal used to setup a connection with the mobile station, in response to receiving the request signal,
wherein the completion signal is transmitted by the mobile station in response to the setup signal.
3. The radio access network apparatus according to claim 1, wherein the first storage area is a temporary storage area.
4. The radio access network apparatus according to claim 1, further comprising:
a memory that comprises the first storage area and the second storage area.
5. The radio access network apparatus according to claim 1, further comprising:
a first memory that comprises the first storage area; and
a second memory that comprises the second storage area,
wherein the first memory is physically different from the second memory.
6. The radio access network apparatus according to claim 1, wherein a capacity of the first storage area is less than a capacity of the second storage area.
7. The radio access network apparatus according to claim 1, wherein the first storage area comprises a plurality of first sub-sections and the second storage area comprises a plurality of second sub-sections, and a number of the second sub-sections in the second storage area is larger than a number of the first sub-sections in first storage area.
8. The radio access network apparatus according to claim 1, wherein the controller controls the first storage area such that new information stored in the first storage area overwrites the oldest information previously stored in the first storage area.
9. A radio access network apparatus comprising:
a first storage are and a second storage area different from the first storage area;
a receiver that receives, from at least one mobile station, a plurality of request signals, each comprising context information used to communicate with a mobile station;
a detector that detects a number of the plurality request signals received by the receiver; and
a controller
wherein, when a number of the plurality of request signals received by the receiver exceeds a predetermined number, the controller controls storage of the context information in the first storage area, in response to receiving the request signal, and
wherein, when a number of the plurality of request signals received by the receiver does not exceed the predetermined number, the controller controls storage of the context information in the second storage area, in response to receiving the request signal.
10. A control method for a radio access network apparatus, the method comprising:
receiving, from a mobile station, a request signal comprising context information used to communicate with the mobile station;
in response to receiving the request signal, allocating a sub-section of a first storage area for storing the context information;
receiving, from the mobile station, a completion signal that indicates that a connection with the mobile station is established, and
in response to receive the completion signal, allocating a sub-section of a second storage area, different from the first storage area, for storing the context information previously allocated to the sub-section of the first storage area.
11. The control method according to claim 10, further comprising:
subsequent to allocating the sub-section of the first storage area, transmitting, to the mobile station, a setup signal.
12. The control method according to claim 10, wherein the first storage area is a temporary storage area.
13. The control method according to claim 10, further comprising:
in response to allocating the sub-section of the first storage area, storing the context information in the allocated sub-section of the first storage area, and
in response to allocating the sub-section of the second storage area, storing the context information in the allocated sub-section of the second storage area.
14. The control method according to claim 13, wherein the storing the context information in the allocated sub-section of the first storage area comprises overwriting the oldest information previously stored in the first storage area.
15. A mobile communication system comprising:
a mobile station; and
a radio access network apparatus,
wherein the radio access network apparatus comprises:
a first storage area and a second storage area different from the first storage area;
a receiver that receives, from the mobile station, a request signal comprising context information used to communicate with the mobile station and subsequently receives, from the mobile station, a completion signal that indicates that a connection with the mobile station is established;
a controller that controls storage of the context information in the first storage area in response to receiving the request signal and that controls storage of the context information in the second storage area in response to receiving the completion signal; and
wherein the mobile station comprises:
a transmitter that transmits, to the radio access network apparatus, the request signal and the completion signal.
16. A non-transitory computer readable medium embodying instructions for controlling a device to implement a control method for radio access network apparatus, the control method comprising:
receiving, from a mobile station, a request signal comprising context information used to communicate with the mobile station;
in response to receiving the request signal, allocating a sub-section of a first storage area for storing the context information;
receiving, from the mobile station, a completion signal that indicates that the connection with the mobile station is established, and
in response to receive the completion signal, allocating a sub-section of a second storage area, different from the first storage area, for storing the context information previously allocated to the sub-section of the first storage area.