阅读说明：本技术 一种提高mos器件或集成电路抗辐照性能的方法 (Method for improving radiation resistance of MOS device or integrated circuit ) 是由 安霞 任哲玄 李艮松 张兴 黄如 于 2019-11-12 设计创作，主要内容包括：本发明公开了一种提高MOS器件或集成电路抗辐照性能的方法,利用纳米级MOS器件引入的应变硅技术的工艺特点,在版图设计时适当调整PMOS器件源漏扩散区长度SA,最终增大沟道中的压应力,从而可以提高沟道中空穴迁移率,提高PMOS器件的常态性能,另一方面,还可以减小总剂量辐照引起的阈值电压漂移,从而减少总剂量辐照对纳米级MOS器件的影响,提高纳米级集成电路抗总剂量辐照性能。(The invention discloses a method for improving the radiation resistance of an MOS device or an integrated circuit, which utilizes the process characteristics of a strained silicon technology introduced by a nano-scale MOS device to properly adjust the length SA of a source-drain diffusion region of a PMOS device during layout design, and finally increase the compressive stress in a channel, thereby improving the cavity mobility in the channel and improving the normal state performance of the PMOS device, and on the other hand, reducing the threshold voltage drift caused by total dose radiation, thereby reducing the influence of the total dose radiation on the nano-scale MOS device and improving the total dose radiation resistance of the nano-scale integrated circuit.)

1. A method for improving the radiation resistance of MOS devices or integrated circuits, which apply strained silicon technology and comprise nanoscale PMOS devices; when the layout design is carried out, the length SA of the source-drain diffusion region of the PMOS device is properly adjusted, and the influence of total dose irradiation is reduced.

2. The method of claim 1, wherein the MOS device is a 90 nm, 65 nm, 45 nm, 32 nm, or more advanced planar device.

3. The method of claim 1, wherein the strained silicon technology comprises one or more of a source drain embedding technology and a strain memory technology.

4. The method of claim 1, in which the PMOS device is a core device and/or an input-output device.

5. The method of claim 1, wherein the MOS device is a 65 nm technology generation device, and wherein the layout design is performed such that the PMOS device source drain diffusion length SA is increased to 0.4 μm or more.

6. The method of claim 1, wherein the PMOS device source drain diffusion length SA is increased by adding dummy gates or manually increasing active area layout area when performing layout design.

7. The method of claim 1 wherein the source drain diffusion length SA of the PMOS device is determined by: and preparing PMOS devices with different lengths SA of the source diffusion region and the drain diffusion region, and comparing the total dose irradiation resistance of the PMOS devices to obtain the lengths SA of the source diffusion region and the drain diffusion region corresponding to the PMOS devices meeting the specific application requirements.

8. The method of claim 7 wherein the source drain diffusion length SA of the PMOS device is determined by:

1) when layout design is carried out, the length SA of a source-drain diffusion region of the PMOS device is changed, and PMOS devices with different SAs are prepared;

2) testing transfer characteristic curves of PMOS devices with different SAs, and extracting threshold voltages of the PMOS devices;

3) carrying out irradiation experiments on PMOS devices with different SAs, testing transfer characteristic curves of the devices after irradiation, and extracting threshold voltages of the devices after irradiation;

4) calculating and comparing threshold voltage drifts of the PMOS devices with different SAs after being irradiated;

5) and selecting the minimum source-drain diffusion region length SA meeting the requirements according to the specific application requirements according to the ratio of the threshold voltage drift of the device caused by the total dose irradiation obtained in the step 5) to the threshold voltage of the device before irradiation obtained in the step 2).

9. The method of claim 8, wherein the threshold voltage of the device is extracted using a constant current method or a maximum transconductance method in steps 2) and 3).

Technical Field

The invention relates to a method for improving the radiation resistance of an MOS device or an integrated circuit, in particular to the layout design of a PMOS device, belonging to the field of microelectronic reliability.

Background

As the microelectronic device technology node enters below 90 nm, in order to overcome the problems of serious mobility degradation and the like, the strained silicon technology is applied to the manufacture of a super-large-scale integrated circuit. The strained silicon technology introduces stress into a device channel through different process methods, and improves the carrier mobility of the channel so as to improve the performance of the device. For example, for 65 nm technology generation devices, the capping layer technology is taken as an example, and the basic principle is the strain memorization technology, namely, a certain stress is applied to the device by covering a strain layer on the device, when the annealing temperature exceeds the turning point, the polysilicon is converted from an elastic state to a plastic state, so that even if the strain layer is removed, the stress is memorized. In addition, Shallow Trench Isolation (STI) processes can also introduce stress in the device channel. Therefore, the magnitude of stress in the channel region of the device can be influenced by appropriate layout design.

On the other hand, with the rapid development of the aerospace technology, higher requirements are put forward on the performance of the integrated circuit working in the space radiation environment. Therefore, the demand for radiation-resistant nanoscale integrated circuits is increasing. However, the existing nanoscale integrated circuits cannot fully meet the requirement of radiation resistance. For example, previous researches show that the degradation of off-state leakage current of 65 nanometer technology generation devices after total dose irradiation is greatly improved compared with the prior art generation, but a certain threshold voltage drift phenomenon still exists, and the performance reduction and even the functional failure of a digital circuit can be caused. In order to enable the nanoscale integrated circuit to normally work in a severe space radiation environment, further radiation resistance optimization of the device is necessary.

The stress in the channel may affect the doping distribution in the channel, or change the gate-oxide trap density/interface quality, etc., which in turn may affect the radiation resistance of the device. Therefore, the radiation resistance of the device can be improved by proper layout design by utilizing the characteristic.

Disclosure of Invention

In order to further improve the total dose irradiation resistance of the MOS device or the integrated circuit, the invention provides a layout design method of the MOS device, which can improve the total dose irradiation resistance of the MOS device or the integrated circuit applying the strained silicon technology.

The method for improving the radiation resistance of the MOS device or the integrated circuit is mainly characterized in that the process characteristics of a strained silicon technology introduced by a nano-scale MOS device are utilized, the length SA of a source-drain diffusion region of the PMOS device is properly adjusted during layout design, and finally the compressive stress in a channel is increased, so that the hole mobility in the channel can be improved, the normal performance of the PMOS device is improved, on the other hand, the threshold voltage drift caused by total dose radiation can be reduced, the influence of the total dose radiation on the nano-scale MOS device is reduced, and the total dose radiation resistance of the nano-scale integrated circuit is improved.

The technical scheme of the invention is as follows:

a method for improving the radiation resistance of MOS devices or integrated circuits, which apply strained silicon technology and comprise nanoscale PMOS devices; when the layout design is carried out, the length SA of the source-drain diffusion region of the PMOS device is properly adjusted, and the influence of total dose irradiation is reduced.

The present invention is directed to the application of strained silicon technology in the future generations of devices, including 90 nm, 65 nm, 45 nm, 32 nm and more advanced planar devices.

The strained silicon technology in each technology generation of each generation factory may be different, and the strained silicon technology applicable to the invention comprises a source and drain region embedding technology (embedded germanium-silicon/carbon-silicon technology), a Strained Memory Technology (SMT) and the like.

In layout design, the PMOS devices involved include core (core) devices and input/output (IO) devices.

The source drain diffusion region length SA is defined as the length from the device gate edge to the source drain diffusion region edge along the device channel direction, and for the minimum size device, the source drain diffusion region length SA default value is generally less than 0.2 microns. The method of the invention properly increases the length SA of the source and drain diffusion regions of the PMOS device in the layout design, the increase range of the length SA of the source and drain diffusion regions of the PMOS device in different technical generations and different strained silicon processes is possibly different, and the length SA of the source and drain diffusion regions is increased, so that the normal state performance and the radiation resistance of the device are enhanced until saturation. For example, for a 65 nanometer technology generation device, the PMOS device source drain diffusion length SA should be increased to 0.4 microns and above.

In the method of the invention, the method for increasing the length SA of the source/drain diffusion region of the PMOS device can be to increase a dummy gate or manually increase the area of an active region plate. Except for the modification of the layout of the PMOS device, other process preparation flows are unchanged, and the device and the circuit are prepared according to the standard process flow.

To determine the optimal length of the source drain diffusion length SA, the following method may be adopted: and preparing PMOS devices with different lengths SA of the source diffusion region and the drain diffusion region, and comparing the total dose irradiation resistance of the PMOS devices to obtain the lengths SA of the source diffusion region and the drain diffusion region corresponding to the PMOS devices meeting the specific application requirements.

1) When layout design is carried out, the length SA of a source-drain diffusion region of the PMOS device is changed, and PMOS devices with different SAs are prepared;

2) testing transfer characteristic curves of PMOS devices with different SAs, and extracting threshold voltages of the PMOS devices;

3) carrying out irradiation experiments on PMOS devices with different SAs, testing transfer characteristic curves of the devices after irradiation, and extracting threshold voltages of the devices after irradiation;

4) calculating and comparing threshold voltage drifts of the PMOS devices with different SAs after being irradiated;

5) and according to the ratio of the threshold voltage drift of the device caused by the total dose irradiation obtained in the step 5) to the threshold voltage of the device before irradiation obtained in the step 2), selecting the minimum source-drain diffusion region length SA meeting the requirement according to the specific application requirement (for example, the threshold voltage drift is less than 5%).

Preferably, the threshold voltage of the device can be extracted in steps 2) and 3) by using a conventional method such as a constant current method or a maximum transconductance method.

And 5) selecting the SA value, wherein specific application requirements need to be considered, generally speaking, the larger the SA, the better the radiation resistance of the device is, but the more precious layout area is wasted, and compromise is needed. Therefore, the minimum SA that meets the application requirements may be selected.

The invention utilizes the process characteristics of the strained silicon technology to properly increase the length SA of the source-drain diffusion region of the PMOS device and finally increase the compressive stress in the channel, thereby improving the hole mobility in the channel and the normal performance of the PMOS device, and on the other hand, reducing the threshold voltage drift caused by total dose irradiation, thereby reducing the influence of the total dose irradiation on the nanoscale MOS device and improving the total dose irradiation resistance of the nanoscale integrated circuit.

The invention has the following advantages:

1. the operation is simple: only the length SA of a source-drain diffusion region of the PMOS device needs to be increased;

2. the application range is wide: the method is suitable for the technical generation of planar devices applying the strained silicon technology;

3. the final effect is good: and meanwhile, the normal state performance and the total dose irradiation resistance of the PMOS device are improved.

Drawings

Fig. 1 is a schematic diagram of the source drain diffusion length SA of the MOS device.

FIG. 2 shows 65 nm PMOS devices with different source drain diffusion length SA at the same overdrive voltage (V)_ov) The lower average drain current is compared to the histogram, with the current normalized.

FIG. 3 is a histogram comparing the average threshold voltage shift of 65 nm PMOS devices with different source/drain diffusion region lengths SA after irradiation with 1Mrad (Si) total dose, with the threshold voltage shift normalized.

Detailed Description

The invention provides a layout design method for improving the radiation resistance of an MOS device, which utilizes the process characteristics of a strained silicon technology to properly increase the length SA of a source-drain diffusion region of a PMOS device and finally increase the compressive stress in a channel, thereby improving the hole mobility in the channel and the normal state performance of the PMOS device, and on the other hand, reducing the threshold voltage drift caused by total dose radiation, reducing the influence of the total dose radiation on a nanoscale MOS device and improving the total dose radiation resistance of a nanoscale integrated circuit. The invention is described in detail below with reference to the figures and examples.