1. A helical multilevel cutting tool, comprising a cutter shank and a cutter head which are integrally formed, characterized by that: the cutter head is provided with a plurality of helical pieces integrally, each helical piece has a cutting blade thereon, a heat emission platform is formed along the cutting blade, a second cutting blade which faces forwardly as viewed in the direction of the cutting operation is formed in front of the heat emission platform, a cutting blade outer surface is formed between the heat emission platform front surface and the second cutting blade, an outer front cutting blade is formed on the top surface of the cutter head at a position where the blade meets the heat emission platform front surface, and a front cutting blade is formed between the second cutting blade and the center of the cutter head top surface.
2. The helical multilevel cutting tool according to claim 1, characterized by that, there is formed a helical positioning platform protruding from the position of the cutter axis to the second cutting blade on the front cutting surface of each helical piece.
3. The helical multilevel cutting tool according to claim 2, characterized by that, there is formed a groove on said helical positioning platform.
4. The helical multilevel cutting tool according to claim 2 or 3, characterized by that, there is formed at least one level of helical multilevel blade between the second cutting blade and the side surface of said helical positioning platform.
5. The helical multilevel cutting tool according to claim 4, characterized by that, a concave helical multilevel blade is included in said helical multilevel blade.
6. The helical multilevel cutting tool according to any of claims 1-5, characterized by that, the length of said outer front cutting blade is equal to or less than a half of the radius from the outer side surface of the heat emission platform to the cutter axis.
7. The helical multilevel cutting tool according to any of claims 2-6, characterized by that, the perpendicular distance of the side surface of said helical positioning platform with respect to the cutter axis is equal to or less than a half of the radius from the outer side surface of the heat emission platform to the cutter axis.
8. The helical multilevel cutting tool according to any of claims 1-7, characterized by that, the angle included between the front surface of said heat emission platform and the cutting blade outer surface at their joint is at least 90\xb0.
9. The helical multilevel cutting tool according to any of claims 1-8, characterized by that, said helical pieces are at least two.
10. The helical multilevel cutting tool according to any of claims 1-9, characterized by that, the cutter shank is one of the following types: a cone shank, a straight shank, a cylinder positioned screw shank, a cylinder positioned thread-hole shank, a cone positioned screw shank, a cone positioned thread-hole shank, an end-surface platform positioned screw shank, and an end-surface platform positioned thread-hole shank.
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 method of fabricating an SRAM memory cell, comprising:
providing a silicon substrate having a first pair of adjacent active regions of given n or p conductivity type well disposed between second and third pairs of adjacent active regions of opposite n or p conductivity type well, the active regions being isolated from one another by isolation regions formed in the substrate;
forming common gates over at least the active regions of the first pair, and over ones of the active regions of the first pair and respective ones of the active regions of the second and third pairs;
patterning a resist layer overlying the active regions of the first pair and over a portion of the isolation regions isolating at least one of each of the active regions of the second and third pairs, such that resist structures are formed on opposite sides of the at least one of each of the active regions of the second and third pairs to equally shadow laterally opposed first and second pocket implants made at same by oppositely directed angles, wherein the patterned resist structures overlying the isolation regions are about equally spaced away from and on opposite sides of the at least one of each of the active regions of the second and third pairs;
implanting one or more dopant species of the opposite n or p conductivity type at an angle into the at least one of each of the active regions in a first pocket implant using the patterned resist layer including the resist structures as an implant mask;
adjusting the rotational orientation between the substrate and the first pocket implant by about 180 degrees; and
implanting the one or more dopant species at about the same but oppositely directed angle into the at least one of each of the active regions in a second pocket implant using the patterned resist layer including the resist structures as an implant mask.
2. The method of claim 1, further comprising removing the resist layer after the second pocket implant step.
3. The method of claim 1, further comprising:
patterning a second resist layer overlying the active regions of the second and third pairs and over a portion of the isolation regions isolating at least one of the active regions of the first pair, such that second resist structures are formed on opposite sides of the at least one of the active regions of the first pair to equally shadow laterally opposed third and fourth pocket implants made at same by oppositely directed angles, wherein the patterned second resist structures overlying the first pair isolation regions are about equally spaced away from and on opposite sides of the at least one of the active regions of the first pair;
implanting one or more second dopant species of the given n or p conductivity type at a second angle into the at least one of the active regions of the first pair in a third pocket implant using the second patterned resist layer including the second resist structures as an implant mask;
adjusting the rotational orientation between the substrate and the third pocket implant by about 180 degrees; and
implanting the one or more second dopant species at about the same but oppositely directed second angle into the at least one of the active regions of the first pair in a fourth pocket implant using the second patterned resist layer including the second resist structures as an implant mask.
4. The method of claim 1, wherein the resist structures formed on opposite sides of the at least one of each of the active regions of the second and third pairs are spaced away from the respective active region by about one overlay error specification.