Claims
- 1. A method of fabricating a semiconductor device in which a memory cell region having a first N-type field-effect transistor and a non-memory cell region having an NPN bipolar transistor and a second N-type field-effect transistor are formed in the same semiconductor base, comprising the steps of:simultaneously forming first and second N-type diffusion layers in surface portions of a semiconductor substrate in said memory cell region and a region in which said bipolar transistor is to be formed, respectively; growing an epitaxial layer on said semiconductor substrate to form said semiconductor base and convert said diffusion layers into buried diffusion layers; and making a threshold voltage of said first field-effect transistor higher than a threshold voltage of said second field-effect transistor.
- 2. A method according to claim 1, further comprising the steps of:simultaneously doping a P-type impurity into channel regions of said first and second field-effect transistors; and doping a P-type impurity only into the channel region of said first field-effect transistor.
- 3. A method of fabricating a semiconductor device having a memory cell region in which a flip-flop including a field effect transistor and a load element is formed and a non-memory cell region in which a bipolar transistor is formed, comprising the steps of:forming at least a base region and an emitter region of said bipolar transistor by rapid thermal annealing; forming said load element after said rapid thermal annealing; forming said load element connected to a storage node diffusion layer of said flip-flop; and doping phosphorus into said connecting portion; and wherein a field-effect transistor having a conductivity type opposite to a conductivity type of said field-effect transistor is used as said load element, and a gate electrode of said field-effect transistor having the opposite type is connected to said storage node diffusion layer.
- 4. A method according to claim 3, wherein a temperature of said rapid thermal annealing is set at to 1150° C.
- 5. A method of fabricating a semiconductor device having a memory cell region in which a flip-flop including a field effect transistor and a load element is formed and a non-memory cell region in which a bipolar transistor is formed, comprising the steps of:forming at least a base region and an emitter region of said bipolar transistor by rapid thermal annealing; forming said load element after said rapid thermal annealing; forming said load element directly connected to a storage node diffusion layer of said flip-flop; and doping phosphorus into said connecting portion.
- 6. A method according to claim 5, wherein a resistive element is used as said load element.
- 7. A method according to claim 5, wherein a field-effect transistor having a conductivity type opposite to a conductivity type of said field-effect transistor is used as said load element, and a gate electrode of said field-effect transistor having the opposite conductivity type is connected to said storage diffusion layer.
- 8. A method according to claim 5, wherein a temperature of said rapid thermal annealing is set at 1000 to 1150° C.
Priority Claims (2)
Number |
Date |
Country |
Kind |
P08-308779 |
Nov 1996 |
JP |
|
P08-358921 |
Dec 1996 |
JP |
|
Parent Case Info
This application is a divisional of application Ser. No. 08/964,907 filed Nov. 5, 1997 now U.S. Pat. No. 6,124,617.
US Referenced Citations (12)