Method of manufacturing an integrated circuit having field effect transistors including a peak in a body dopant concentration

• US 9,355,909 B2
• Filed: 01/07/2014
• Issued: 05/31/2016
• Est. Priority Date: 03/12/2009
• Status: Active Grant

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies AG
• Inventors: Meyer, Thorsten, Decker, Stefan, Krischke, Norbert, Kadow, Christoph
• Primary Examiner(s): Pham, Hoai V
• Application Number:
  US14/148,776
• Publication Number:
  US 20140120673A1
• Time in Patent Office: 875 Days
• US Class Current: 1/1
• CPC Class Codes: H01L 21/26513 of electrically active species
• CPC Class Codes: H01L 21/266 using masks H01L21/26586 takes precedence
• CPC Class Codes: H01L 21/823412 with a particular manufacturing method of the channel structures, e.g. channel implants, halo or pocket implants, or channel materials
• CPC Class Codes: H01L 21/823807 with a particular manufacturing method of the channel structures, e.g. channel implants, halo or pocket implants, or channel materials
• CPC Class Codes: H01L 27/088 the components being field-effect transistors with insulated gate
• CPC Class Codes: H01L 29/105 with vertical doping variation H01L29/7827 takes precedence
• CPC Class Codes: H01L 29/4236 within a trench, e.g. trench gate electrode, groove gate electrode
• CPC Class Codes: H01L 29/66537 using a self aligned punch through stopper or threshold implant under the gate region H01L29/66606 takes precedence
• CPC Class Codes: H01L 29/78 with field effect produced by an insulated gate H01L29/7725, H01L29/775, H01L29/778 take precedence

Abstract

An integrated circuit having field effect transistors and manufacturing method. One embodiment provides an integrated circuit including a first FET and a second FET. At least one of source, drain, gate of the first FET is electrically connected to the corresponding one of source, drain, gate of the second FET. At least one further of source, drain, gate of the first FET and the corresponding one further of source, drain, gate of the second FET are connected to a circuit element, respectively. A dopant concentration of a body along a channel of each of the first and second FETs has a peak at a peak location within the channel.

Claims

1. A method of forming an integrated circuit, comprising:

forming a first FET and a second FET;

electrically connecting at least one of source, drain, gate of the first FET to the corresponding one of source, drain, gate of the second FET; and

connecting at least one further of source, drain, gate of the first FET and the corresponding one further of source, drain, gate of the second FET to a circuit element, respectively; and

wherein the formation of the first and second FET includes forming a body of each of the first and second FETs having a dopant concentration along a channel of the respective FET that includes a peak at a peak location within the channel, and further comprising forming the first and second FETs as Trench FETs comprising trenches extending into a semiconductor substrate from a first surface of the semiconductor substrate, and wherein forming the body of each of the first and second FETs includes;

implanting dopants into the semiconductor substrate such that a peak concentration of the implanted dopants has a greater distance to the first surface than a pn junction between the source and the body.

2. The method of claim 1, comprising forming the body of each of the first and second FETs includes:

implanting dopants into a semiconductor substrate and annealing implant damages such that a fraction of a channel area of each of the first and second FETs having a dopant concentration of at least 95% of a value at the peak location to an overall channel area of the respective FET is at least 15%.

3. The method of claim 1, further comprising:

forming the first FET as a power FET and forming the second FET as a sense FET having an area that is smaller than the area of the power FET.

4. The method of claim 1, further comprising:

connecting the gate of the first FET to the gate of the second FET;

connecting one of source and drain of the first FET to the corresponding one of source and drain of the second FET; and

connecting the other one of source and drain of the first FET and the other one of source and drain of the second FET to the circuit element.

5. A method, comprising:

forming a first FET and a second FET, wherein the first FET is a power FET and the second FET is a sense FET;

connecting at least one of a source, drain, or gate of the first FET to the corresponding one of a source, drain, or gate of the second FET;

connecting at least one further of the source, drain, or gate of the first FET and the corresponding one further of source, drain, or gate of the second FET to a circuit element, respectively;

wherein forming the first FET and the second FET include forming a dopant concentration profile of a body along a channel of each of the first and second FETs having a peak at a peak location within the channel, wherein a value of the dopant concentration profile of the body at the peak location of each of the first and second FETs is larger or at least equal to any value of the dopant concentration profile of the body in an extension region that extends into the source,

wherein the dopant concentration profile of the body of the first FET and the dopant concentration profile of the body of the second FET follow substantially similar contours along the channel of the first and second FETs respectively, and further comprising forming the first and second FETs as Trench FETs comprising trenches extending into a semiconductor substrate from a first surface of the semiconductor substrate, and wherein forming the body of each of die first and second FETs includes;

implanting dopants into the semiconductor substrate such that a peak concentration of the implanted dopants has a greater distance to the first surface than a pn junction between the source and the body.

6. The method of claim 5, wherein the dopant concentration profile of the body of each of the first and second FETs is declining along the channel from the peak location to a pn junction between the body and source.

7. The method of claim 5, wherein a fraction of a channel area of each of the first and second FETs having a dopant concentration of the body of at least 95% of a value at the peak location to an overall channel area of the respective FET is at least 15%.

8. The method of claim 5, wherein the dopant concentration profile of the body of each of the first and second FETs has a single peak within the channel, the dopant concentration profile of the body declining to both ends of the channel in the direction of source and drain.

9. The method of claim 5,

wherein the gate of the first FET is connected to the gate of the second FET;

one of the source and drain of the first FET is connected to the corresponding one of the source and drain of the second FET; and

wherein the other one of the source and drain of the first FET and the other one of the source and drain of the second FET are connected to the circuit element.

10. The method of claim 5, wherein the dopant concentration profile of the body of each of the first and second FETs continuously declines within the source.