CN103943554B - The method extending the technique waiting time of ultra-low dielectric constant material - Google Patents

Abstract

The invention provides a method for prolonging the process waiting time of ultra-low dielectric constant materials, comprising: first step: forming copper interconnection in ultra-low dielectric constant material; second step: forming copper interconnection in ultra-low dielectric constant material After the copper interconnection is formed in , calculate the waiting time for depositing the barrier layer and judge whether the waiting time for depositing the barrier layer exceeds the specified waiting time, and perform the following third step when the time for depositing the barrier layer exceeds the specified waiting time To the sixth step; the third step: the silicon wafer surface is treated for the first time, such as utilizing chemical mechanical grinding to treat the silicon wafer surface for the first time; the fourth step: after the silicon wafer surface is treated for the first time High temperature dehumidification of the silicon wafer; the fifth step: after the high temperature dehumidification of the silicon wafer, the surface of the copper is treated with hydrogen plasma for the second time; the sixth step: after the second treatment of the copper surface, the deposition barrier layer.

Description

Method for prolonging the process waiting time of ultra-low dielectric constant materials

technical field

The invention relates to the field of semiconductor manufacturing, and more specifically, the invention relates to a method for prolonging the process waiting time (Queuetime) of ultra-low dielectric constant materials.

Background technique

As we all know, the traditional ULSI interconnection uses the Al/SiO ₂ system. To improve the performance of ULSI by changing p and k, it is necessary to develop a new interconnection system. As shown in Figure 1, first, metals with low resistivity can be used instead of A1 as the interconnection material to reduce the interconnection resistance and increase the speed of ULSI. In response to this aspect, IBM announced in 1998 that it had developed copper (the resistivity of Cu is 60% of A1) as a metal interconnection, which has already reached the industrial level. Since only silver exhibits a higher conductivity at room temperature, but the difference is only 5%, an improvement in this respect would be hopeless. Secondly, low dielectric constant materials (k<4) can be further used to replace the existing SiO2 (the dielectric constant of SiO2 is 4.2) as the insulating medium between the interconnection layers or between each layer of interconnection lines, reducing the interconnection The effects of latency and power dissipation will be more pronounced. Therefore, at 40nm and below, ultra-low dielectric constant materials are generally used in the semiconductor manufacturing process as the dielectric layer of the copper back-end interconnection.

In order to reduce the dielectric constant, the ultra-low dielectric constant material (k<2) generally adopts a loose and porous structure. After forming copper interconnects and performing copper CMP, it is necessary to deposit a layer of SiOC or Si ₃ N ₄ on the ultra-low dielectric constant material in time to seal the loose and porous structure of the ultra-low dielectric constant material and prevent a large amount of water Gases and other impurities are absorbed into the dielectric layer material, which can adversely affect electromigration and time-dependent dielectric breakdown. Specifically, the longer the process wait time, the more moisture and the worse the performance of electromigration.

Therefore, the industry generally limits the waiting time in the relevant process to reduce the absorption of water vapor and other impurities by ultra-low dielectric constant materials. However, due to the tight waiting time limit, the waiting time between some processes cannot even exceed two hours. Sometimes some silicon wafers are too late to be processed. If the waiting time is exceeded, they can only be scrapped, seriously affecting production capacity and causing waste; Appropriate methods are urgently needed to appropriately extend the desirable latency without adversely affecting electromigration and time-dependent dielectric breakdown.

Contents of the invention

The technical problem to be solved by the present invention is to provide a method for prolonging the waiting time after the copper CMP (chemical mechanical polishing) process in view of the above-mentioned defects in the prior art

In order to achieve the above technical purpose, according to the present invention, a method for prolonging the process waiting time of ultra-low dielectric constant materials is provided, which includes:

The first step: forming copper interconnects in ultra-low dielectric constant materials;

Step 2: After forming the copper interconnection in the ultra-low dielectric constant material, calculate the waiting time for depositing the barrier layer and judge whether the waiting time for depositing the barrier layer exceeds the specified waiting time, and if the time for depositing the barrier layer exceeds the specified waiting time In the case of waiting time, perform the following third step to sixth step;

The third step: performing the first treatment on the surface of the silicon wafer, for example, performing the first treatment on the surface of the silicon wafer by chemical mechanical grinding;

The fourth step: dehumidify the silicon wafer at high temperature after the first treatment on the surface of the silicon wafer;

The fifth step: After dehumidifying the silicon wafer at high temperature, use hydrogen plasma to treat the copper surface for the second time;

Sixth step: Depositing a barrier layer after the second treatment of the copper surface.

Preferably, if it is judged in the second step that the time for depositing the barrier layer does not exceed the prescribed waiting time, the second step can be performed directly to deposit the barrier layer.

Preferably, the barrier layer is made of SiOC or Si ₃ N ₄ .

Preferably, the ultra-low dielectric constant material is a porous material containing silicon, carbon, hydrogen, and oxygen.

Preferably, the thickness of the ultra-low dielectric constant material removed in the first treatment on the surface of the silicon wafer is 100-500A.

Preferably, the temperature in the high temperature dehumidification process is 250-400°C, and the time is 10s to 300s.

Preferably, in the second treatment of the copper surface by hydrogen plasma, the gas used is pure hydrogen or hydrogen-helium mixture gas or argon, and the treatment time is 30s to 200s.

The present invention can effectively prolong the waiting time through relevant treatment measures, thereby reducing its influence on electromigration and time-related dielectric breakdown. Among them, the present invention prolongs the waiting time after the copper process, reduces the scrapped silicon wafers caused by exceeding the waiting time, and thus saves the cost.

Description of drawings

A more complete understanding of the invention, and its accompanying advantages and features, will be more readily understood by reference to the following detailed description, taken in conjunction with the accompanying drawings, in which:

Fig. 1 schematically shows a flow chart of a method for prolonging the process waiting time of ultra-low dielectric constant materials according to a preferred embodiment of the present invention.

It should be noted that the accompanying drawings are used to illustrate the present invention, but not to limit the present invention. Note that drawings showing structures may not be drawn to scale. And, in the drawings, the same or similar elements are marked with the same or similar symbols.

detailed description

In order to make the content of the present invention clearer and easier to understand, the content of the present invention will be described in detail below in conjunction with specific embodiments and accompanying drawings.

The invention relates to a method for prolonging the process waiting time of ultra-low dielectric constant materials. In the present invention, after the copper interconnection is formed in the ultra-low dielectric constant material, the waiting time for depositing barrier layers such as SiOC or Si ₃ N ₄ exceeds the specified waiting time, and a small amount of CMP is first performed to treat the surface of the silicon wafer, and then Dehumidification at 350°C, and finally treatment with hydrogen plasma, after the treatment, the normal process of depositing barrier layers such as SiOC or Si ₃ N ₄ is carried out.

Specifically, FIG. 1 schematically shows a flow chart of a method for extending the process waiting time of an ultra-low dielectric constant material according to a preferred embodiment of the present invention.

As shown in Figure 1, the method for prolonging the process waiting time of ultra-low dielectric constant materials according to a preferred embodiment of the present invention includes:

The first step S1: forming copper interconnection in the ultra-low dielectric constant material; preferably, the ultra-low dielectric constant material is a material containing silicon, carbon, hydrogen, oxygen and other elements containing a large number of pores, such as BDII, etc. ;

Second step S2: After forming the copper interconnection in the ultra-low dielectric constant material, calculate the waiting time for depositing the barrier layer and judge whether the waiting time for depositing the barrier layer exceeds the specified waiting time, and the time for depositing the barrier layer exceeds the specified time In the case of waiting time, the following third step S3 to sixth step S6 are performed; for example, the prescribed waiting time can be set to 1-2 hours, or 4-8 hours; and some processes wait for the deposition of barrier layer Time 8-48 hours;

The third step S3: performing the first treatment (partial treatment) on the surface of the silicon wafer, for example, using chemical mechanical grinding to perform the first treatment on the surface of the silicon wafer; preferably, the first treatment on the surface of the silicon wafer removes The thickness of the ultra-low dielectric constant material is generally 100-500A.

Fourth step S4: performing high-temperature dehumidification on the silicon wafer after the first treatment on the surface of the silicon wafer; preferably, the temperature in the high-temperature dehumidification process is 250-400° C., and the time is 10 s to 300 s.

The fifth step S5: after the high-temperature dehumidification of the silicon wafer, the surface of the copper is treated with hydrogen plasma for the second time; preferably, in the second treatment of the surface of copper with hydrogen plasma, the gas used It is pure hydrogen (hydrogen atom or hydrogen ion) or hydrogen-helium mixture gas or argon gas, and the processing time is 30s to 200s.

The sixth step S6: depositing a barrier layer after the second treatment on the copper surface (for example, the material of the barrier layer is SiOC or Si ₃ N ₄ , etc.).

Wherein, if it is judged in the second step S2 that the time for depositing the barrier layer does not exceed the prescribed waiting time, the barrier layer can be deposited directly after the second step S2 (for example, the material of the barrier layer is SiOC or Si ₃ N ₄ etc.) (seventh step S7).

After the present invention forms the copper interconnection in the ultra-low dielectric constant material, when the waiting time for depositing barrier layers such as SiOC or Si ₃ N ₄ exceeds the specified waiting time, the current industry can only scrap the silicon wafer, while the present invention In this method, a small amount of CMP is first performed on the overtimed silicon wafer, the surface of the silicon wafer is treated, and then high-temperature dehumidification is performed, and finally the surface of copper is treated with hydrogen plasma. After the treatment, the normal deposition of SiOC or Si ₃ N is carried out. The _4th barrier layer process effectively prolongs the waiting time (that is, it can not affect electromigration and time-related dielectric breakdown under the extended waiting time), reducing the scrapped silicon wafers caused by overtime, Reduced costs.

It can be understood that although the present invention has been disclosed above with preferred embodiments, the above embodiments are not intended to limit the present invention. For any person skilled in the art, without departing from the scope of the technical solution of the present invention, the technical content disclosed above can be used to make many possible changes and modifications to the technical solution of the present invention, or be modified to be equivalent to equivalent changes. Example. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention, which do not deviate from the technical solution of the present invention, still fall within the protection scope of the technical solution of the present invention.

Claims (6)

1. the method for the technique waiting time extending ultra-low dielectric constant material, it is characterised in that including:

First step: form copper-connection in ultra-low dielectric constant material；

Second step: formed in ultra-low dielectric constant material after copper-connection, calculate the waiting time of deposit barrier layer and judge whether the waiting time of deposit barrier layer exceedes the waiting time of regulation, and performing following third step when the time of deposit barrier layer exceedes the waiting time of regulation to the 6th step；

Third step: silicon chip surface carries out first time process, utilizes cmp that silicon chip surface carries out first time process, and the first time that silicon chip surface is carried out processes the thickness of the ultra-low dielectric constant material removed and is

4th step: after silicon chip surface is carried out first time process, silicon chip is carried out the dehumidifying of high temperature；

5th step: utilize hydrogen plasma that the surface of copper carries out second time after silicon chip carries out the dehumidifying of high temperature and process；

6th step: the surface of copper is being carried out deposit barrier layer after second time processes.

2. the method for the technique waiting time of prolongation ultra-low dielectric constant material according to claim 1, it is characterized in that, judge in the second step when the time of deposit barrier layer not less than waiting time of regulation can Direct precipitation barrier layer after second step.

3. the method for the technique waiting time of prolongation ultra-low dielectric constant material according to claim 1 and 2, it is characterised in that the material on barrier layer is SiOC or Si₃N₄。

4. the method for the technique waiting time of prolongation ultra-low dielectric constant material according to claim 1 and 2, it is characterised in that described ultra-low dielectric constant material is the material containing silicon, carbon, hydrogen, oxygen element containing hole.

5. the method for the technique waiting time of prolongation ultra-low dielectric constant material according to claim 1 and 2, it is characterised in that the temperature in the dehumidification process of high temperature is 250-400 DEG C, the time is 10s to 300s.

6. the method for the technique waiting time of prolongation ultra-low dielectric constant material according to claim 1 and 2, it is characterized in that, in utilizing hydrogen plasma that the second time on the surface of copper is processed, the gas used is pure hydrogen or hydrogen helium gas mixture or argon, and the process time is 30s to 200s.