CN103926120A

CN103926120A - Preparation method of SEM sample

Info

Publication number: CN103926120A
Application number: CN201410106490.3A
Authority: CN
Inventors: 郑春生; 张志刚; 徐灵芝; 张文广
Original assignee: Shanghai Huali Microelectronics Corp
Current assignee: Shanghai Huali Microelectronics Corp
Priority date: 2014-03-20
Filing date: 2014-03-20
Publication date: 2014-07-16

Abstract

The invention discloses a preparation method of a SEM sample, which belongs to the integrated circuit manufacture field. The method comprises the following steps: providing a semiconductor structure having a groove to be filled, filling the groove by employing an interlayer dielectric layer high depth ratio process technology; performing heat treatment, corroding by acid solution to form the SEM sample. By employing the preparation method, ILD HARP can be more compact through heat treatment at low temperature, and can resist the erosion of hydrofluoric acid HF. The slit filling effect can be assessed by employing the simple and easy SEM mode and the hydrofluoric acid HF corrosion processing mode, and the preparation method is suitable for a novel logic device structure and its technology integration.

Description

A kind of SEM sample preparation methods

Technical field

The present invention relates to inherit circuit and manufacture field, relate in particular to a kind of SEM sample preparation methods.

Background technology

Since 65/45 nm technology node, before metal, Filled Dielectrics technique has started to transfer extensive use sub-atmospheric pressure chemical vapor deposition method (SACVD HARP) to from high-density plasma technique (HDPPSG/HDPUSG) and has carried out trench oxide filling at present.

But, the filling capacity of sub-atmospheric pressure chemical vapor deposition method is significantly enhanced with respect to traditional high-density plasma technique, but when applying this technique, also produced a new difficult problem: at definite interlayer dielectric layer (Inter Layer Dielectric, be called for short ILD) be not suitable for adopting common scanning electron microscope (SEM) mode to assess filling effect when gap filling effect, and conventionally adopt expensive transmission electron microscope (TEM) mode to assess scanning, as shown in Figure 1, (each sample is greater than 2000 yuan) with high costs, and sampling rate is also very low, and (every sample can only check the scope that is less than 10 metal-oxide-semiconductors, and core device region has billions of metal-oxide-semiconductors).Therefore need a kind of way simple and that sampling rate is higher badly and assess ILD filling effect.

The conventional mode in order to assess gap filling situation has:

Focused ion beam microscope (Focused Ion Beam, be called for short FIB) scan mode, but the too low and not clearly problem of image of sampling rate still there is, as shown in Figure 2;

Scanning electron microscope (scanning electron microscope is called for short SEM) scan mode, can obviously improve sampling rate, for example: a sample can check thousands of even tens thousand of metal-oxide-semiconductors.But when adopting SEM mode to carry out sample preparation, need to pass through the corrosion treatment of hydrofluorite HF, and ILD HARP oxide is easy to be eroded by hydrofluorite HF, forms a large hole (as shown in Figure 3), thereby affects judged result.

Chinese patent (CN102446740B) discloses and the invention provides a kind of technology integrating method that improves before-metal medium layer PMD space filling characteristic.Its processing step is as follows: 1) on the active area of semiconductor silicon substrate, form grid structure; 2) carry out upper photoresistance technique, photoresistance is sprayed on the crystal column surface of High Rotation Speed by nozzle, and is coated on equably crystal column surface under the effect of centrifugal force, forms the photoresistance film of even thickness; 3) carry out graphical treatment, the photoresist layer of Semiconductor substrate is exposed respectively, layout figure is transferred on the photoresist layer of Semiconductor substrate; 4) use dry etching polysilicon gate; 5) remove photoresistance, form and be with slotted grid structure.

This patent reduces the depth-width ratio of the PMD packing space of specific region, thereby improves the zero-clearance filling capacity of PMD processing procedure in specific region, has reduced before-metal medium layer PMD and has formed cavity, can improve yield rate and the yield of corresponding product, is very suitable for practicality.But do not solve while adopting SEM mode to carry out sample preparation, ILD HARP oxide is easy to be eroded by hydrofluorite HF, forms a large hole, thereby affects the problem of judged result.

Chinese patent (CN102412263B) discloses and the present invention relates to a kind of semiconductor devices with pre-metal dielectric filling structure and preparation method thereof.Described semiconductor devices comprises substrate, is formed at the groove isolation construction in described substrate and is formed at the polysilicon gate layer of described substrate surface, and described polysilicon gate layer forms groove in the position of described groove isolation construction.

The semiconductor devices with pre-metal dielectric filling structure of this patent has reduced the depth-width ratio in the gap between adjacent two grids, in the time that Filled Dielectrics before metal is in described gap, be not easy to produce cavity, avoid in follow-up tungsten plug technique, tungsten enters cavity and causes obtaining the problem of conducting between neighboring gates, is conducive to the raising of yield.But do not solve while adopting SEM mode to carry out sample preparation, ILD HARP oxide is easy to be eroded by hydrofluorite HF, forms a large hole, thereby affects the problem of judged result.

Summary of the invention

When the present invention adopts SEM mode to carry out sample preparation for solving, ILD HARP oxide is easy to be eroded by hydrofluorite HF, forms a large hole, thereby affects the problem of judged result, thereby a kind of technical scheme of SEM sample preparation methods is provided.

Invent described a kind of SEM sample preparation methods, comprise the steps:

Step 1, provide a semiconductor structure with groove to be filled, adopt inter-level dielectric floor height depth than making technology, described groove to be filled;

Step 2, heat-treat;

Step 3, acid liquid corrosion form SEM sample.

Preferably, described method also comprises step 4, adopts SEM to carry out failure analysis to described SEM sample.

Preferably, thermal treatment is nitrogen thermal treatment described in step 2, and temperature is 300 DEG C～500 DEG C.

Preferably, described nitrogen gas concn is: 5L/min～20L/min.

Preferably, described heat treated temperature is: 400 DEG C.

Preferably, the described heat treated time is: 15min～2h.

Preferably, described in step 3, acid solution is hydrofluorite.

Beneficial effect of the present invention:

The present invention can allow ILD HARP finer and close by the thermal treatment of low temperature, the erosion that more can resist hydrofluorite HF.Thereby can adopt the mode of simple SEM mode and hydrofluorite HF corrosion treatment to assess gap filling effect, the method be applicable to New kind logical component structure and technique integrated in.

Brief description of the drawings

Fig. 1 is the sample scintigram of transmission electron microscope;

Fig. 2 is the sample scintigram of focused ion beam microscope;

Fig. 3 is the sample scintigram of scanning electron microscope;

Fig. 4 is a kind of SEM sample preparation methods process flow diagram of the present invention;

Fig. 5 is the sample scanning electron microscope scintigram adopting after this method is filled.

Embodiment

Below in conjunction with the drawings and specific embodiments, the invention will be further described, but not as limiting to the invention.

As shown in Figure 4, the invention provides a kind of SEM sample preparation methods, comprise the steps:

Step 1, provide a semiconductor structure with groove to be filled, adopt inter-level dielectric floor height depth than making technology, groove to be filled;

Step 2, heat-treat;

Step 3, acid liquid corrosion form SEM sample.

After thermal treatment, in the time that scanning electron microscope detects the cavity of sample, make ILDHARP finer and close, more can resist the erosion of hydrofluorite HF, as shown in Figure 5.

In a preferred embodiment, method also comprises step 4, adopts SEM to carry out failure analysis to SEM sample.

In a preferred embodiment, thermal treatment is nitrogen thermal treatment, and temperature is 300 DEG C～500 DEG C.

In a preferred embodiment, nitrogen gas concn is: 5L/min～20L/min.

In a preferred embodiment, when temperature is the thermal treatment of low temperature of 400 DEG C, the ILDHARP of sample is finer and close, best results.

In a preferred embodiment, the heat treated time is: 15min～2h.

In a preferred embodiment, the acid solution in step 3 is hydrofluorite.

The foregoing is only preferred embodiment of the present invention; not thereby limit embodiments of the present invention and protection domain; to those skilled in the art; the scheme that being equal to of should recognizing that all utilizations instructions of the present invention and diagramatic content done replaces and apparent variation obtains, all should be included in protection scope of the present invention.

Claims

1. a SEM sample preparation methods, is characterized in that, comprises the steps:

Step 2, heat-treat;

Step 3, acid liquid corrosion form SEM sample.

2. a kind of SEM sample preparation methods as claimed in claim 1, is characterized in that, described method also comprises step 4, adopts SEM to carry out failure analysis to described SEM sample.

3. a kind of SEM sample preparation methods as claimed in claim 1, is characterized in that, thermal treatment is nitrogen thermal treatment described in step 2, and temperature is 300 DEG C～500 DEG C.

4. a kind of SEM sample preparation methods as claimed in claim 1, is characterized in that, described nitrogen gas concn is: 5L/min～20L/min.

5. a kind of SEM sample preparation methods as claimed in claim 1, is characterized in that, described heat treated temperature is: 400 DEG C.

6. a kind of SEM sample preparation methods as claimed in claim 1, is characterized in that, the described heat treated time is: 15min～2h.

7. a kind of SEM sample preparation methods as claimed in claim 1, is characterized in that, acid solution is hydrofluorite described in step 3.