CN101134286A - Composite chemical mechanical polishing method and method for manufacturing shallow trench isolation structure - Google Patents

Abstract

A composite chemical mechanical polishing method is disclosed, which comprises providing a polishing slurry, and performing a main polishing step at a first polishing speed. Then, an auxiliary polishing step is performed. The auxiliary grinding step is to provide grinding liquid in the first time, add solvent in the second time and grind at the second grinding speed, which is lower than the first grinding speed.

Description

Compound Chemical Mechanical Polishing Method and Manufacturing Method of Shallow Trench Isolation Structure

technical field

The invention relates to a chemical mechanical polishing method and a manufacturing method of a semiconductor structure, and in particular to a compound chemical mechanical polishing method and a manufacturing method of a shallow trench isolation structure.

Background technique

In the semiconductor process, as the size of the components continues to shrink, the lithography exposure resolution also increases relatively, and with the reduction of the exposure depth of field, the requirements for the level of fluctuations on the wafer surface are more stringent. Therefore, how to maintain a good flatness of the chip during the fabrication process is an important issue.

Currently, the wafer planarization (Planarization) process relies on a chemical mechanical polishing (CMP) process to complete. For the chemical mechanical polishing process, especially the traditional silicon-based (silica based) shallow trench isolation layer chemical mechanical polishing (STI-CMP) process, generally speaking, it has low cost, high polishing rate and high planarization efficiency. advantage.

However, there are still some disadvantages in the chemical mechanical polishing process of the shallow trench isolation layer. For example, in the shallow trench isolation layer chemical mechanical polishing process, the selectivity of oxide to nitride (oxide tonitride) cannot be improved, resulting in under polishing or over polishing. problems, while excessive grinding can cause dishing. Moreover, in order to avoid the occurrence of this problem, a backup photomask (reserve mask, RM) is even required to assist the process. However, this method has the problem of adding a photolithography and etching process to form the reverse photomask, which complicates the process and increases the cost. In addition, the shallow trench isolation layer chemical mechanical polishing process often has the problem that the thickness and uniformity of the shallow trench oxide layer are not easy to control, which affects the reliability of the process.

Contents of the invention

In view of this, the object of the present invention is to provide a compound chemical mechanical polishing method, which can avoid the problem of under-grinding or over-grinding, and can improve the uniformity of the chip surface and the reliability of the process.

Another object of the present invention is to provide a method for manufacturing a shallow trench isolation structure, which can avoid dishing and improve the flatness and process reliability of the shallow trench isolation structure.

The present invention proposes a composite chemical mechanical polishing method, which is suitable for flattening a structure. The composite chemical mechanical polishing method provides a slurry (slurry) first, and performs a main polishing at a first polishing speed. )step. Then, an assisted polishing step is performed to planarize the structure. Wherein, the auxiliary grinding step is to provide grinding liquid within a first time, and then add a solvent within a second time, and grind at a second grinding speed, and the second grinding speed is lower than the first grinding speed. speed.

According to the compound chemical mechanical polishing method described in the embodiments of the present invention, the solvent includes deionized water (DIW).

According to the compound chemical mechanical polishing method described in the embodiments of the present invention, the above-mentioned first time is between 0 and 20 seconds.

According to the compound chemical mechanical polishing method described in the embodiments of the present invention, the above-mentioned second time is between 2 and 20 seconds.

According to the compound chemical mechanical polishing method described in the embodiments of the present invention, the above-mentioned slurry is, for example, a high selectivity slurry (HSS). In addition, the aforementioned polishing solution is, for example, a solution containing cerium oxide (CeO ₂ ).

The present invention also proposes a method for manufacturing a shallow trench isolation structure. First, a substrate is provided, on which a patterned mask layer has been formed, and at least one trench has been formed in the substrate, and the mask layer is exposed. out of the groove. Then, a dielectric layer is formed on the substrate to fill in the trench. Next, a main grinding step is performed to remove part of the dielectric layer. Afterwards, an auxiliary grinding step is performed to remove part of the dielectric layer and part of the mask layer. The auxiliary grinding step is to provide a grinding liquid in a first time, and then add a solvent in a second time, and grind at a grinding speed, and the grinding speed is lower than that of the main grinding step. Then, the mask layer is removed.

According to the manufacturing method of the shallow trench isolation structure described in the embodiment of the present invention, the solvent includes deionized water.

According to the manufacturing method of the shallow trench isolation structure described in the embodiment of the present invention, the above-mentioned first time is between 0 and 20 seconds.

According to the manufacturing method of the shallow trench isolation structure described in the embodiment of the present invention, the above-mentioned second time is between 2 and 20 seconds.

According to the manufacturing method of the shallow trench isolation structure described in the embodiment of the present invention, the above-mentioned polishing liquid is, for example, a high selectivity polishing liquid. In addition, the above-mentioned polishing solution is, for example, a solution containing cerium oxide.

In the composite chemical mechanical polishing method of the present invention, the chemical mechanical polishing process is divided into a main grinding step and an auxiliary grinding step, and the grinding speed of the auxiliary grinding step is lower than that of the main grinding step, so there will be no existing excessive grinding The problem affects the reliability of the process. In addition, the manufacturing method of the shallow trench isolation structure using the compound chemical mechanical polishing method can not only ensure that the material to be polished can be completely polished, but also avoid dishing, and can improve the flatness of the chip surface.

In order to make the above and other objects, features and advantages of the present invention more comprehensible, the present invention will be described in more detail below with reference to the accompanying drawings and preferred embodiments.

Description of drawings

FIG. 1 is a flow chart of steps of a compound chemical mechanical polishing method according to an embodiment of the present invention.

2A to 2G are cross-sectional views of the manufacturing process of the shallow trench isolation structure according to an embodiment of the present invention.

simple notation

100, 102, 104, 11O: steps

210: base

202: pad oxide layer

204, 204a: mask layer

206: opening

208: Groove

210, 210a: dielectric layer

210b: shallow trench isolation structure

Detailed ways

FIG. 1 is a flow chart of steps of a compound chemical mechanical polishing method according to an embodiment of the present invention.

Referring to FIG. 1 , firstly, a main polishing step (step 100 ) is performed. The main grinding step is to provide a slurry (slurry) at a grinding speed (V ₁ ). Wherein, the slurry may be, for example, a high selectivity slurry (HSS), which is, for example, a solution containing cerium oxide (CeO ₂ ).

The above-mentioned main grinding step is the same as the general chemical mechanical grinding process. The purpose is to remove most of the materials to be ground in a short time. In order to provide a high grinding rate, once the interface between different materials is exposed, the main The grinding step will stop, but at this time there will still be some material to be ground.

Please continue to refer to FIG. 1 , after the main polishing step (step 100 ), an assisted polishing step (step 110 ) is performed. The auxiliary grinding step is to provide a grinding liquid for a period of time (T ₁ ) (step 102 ), and no grinding is performed at this time. Then, add a solvent within a time (T ₂ ), and grind at a grinding speed (V ₂ ).

Wherein, the time (T ₁ ) for providing the grinding liquid in step 102 is, for example, between 0 and 20 seconds, and the grinding liquid can be the same as the grinding liquid used in the main grinding step. The polishing solution is, for example, a solution containing cerium oxide (CeO ₂ ). In addition, the time (T ₂ ) for adding the solvent in step 104 is, for example, 2 to 20 seconds, and the solvent is, for example, deionized water (DIW). Also, the grinding rate (V ₂ ) of the auxiliary grinding step is smaller than the grinding rate (V ₁ ) of the main grinding step

It is worth noting that if the current chemical mechanical polishing machine is restarted for grinding after the main grinding step is stopped, it will be performed at a high grinding rate because it uses the same parameters as the main grinding step for grinding. , and therefore often cause the problem of over-grinding, which in turn causes depressions on the chip surface and affects the reliability of the process. However, the auxiliary grinding step of the present invention does not grind when the grinding liquid is provided, and then grinds after adding solvent, so its grinding speed will be slower than that of the main grinding step, so there will be no excessive grinding , causing the problem of dishing phenomenon. On the other hand, the above-mentioned auxiliary polishing step can also be applied to a chemical mechanical polishing rework process, so as to increase the flatness of the chip. All in all, the compound chemical mechanical grinding method of the present invention can not only ensure that the material to be ground can be completely ground clean, but also avoid the disk phenomenon caused by the existing excessive grinding, which affects the reliability of the process.

Hereinafter, examples will be given to illustrate the compound chemical mechanical polishing method of the present invention. In the following description, the manufacturing method of the shallow trench isolation structure (STI) is used as an embodiment of the present invention, however, the compound chemical mechanical polishing method of the present invention is not limited to this embodiment, and can also be applied to other needs In the semiconductor process of the chemical mechanical polishing process.

2A to 2G are cross-sectional views of the manufacturing process of the shallow trench isolation structure according to an embodiment of the present invention.

First, please refer to FIG. 2A , a substrate 200 is provided, and the substrate 200 is, for example, a silicon substrate. Afterwards, a pad oxide layer 202 and a mask layer 204 are formed on the substrate 200 . Wherein, the material of the pad oxide layer 202 is, for example, silicon oxide, and its forming method is, for example, thermal oxidation. In addition, the material of the mask layer 204 is, for example, silicon nitride, and its forming method is, for example, chemical vapor deposition.

Next, referring to FIG. 2B , an opening 206 is formed in the mask layer 204 and the pad oxide layer 202 . The opening 206 is formed by, for example, forming a patterned photoresist layer (not shown) on the mask layer 204, and then using the patterned photoresist layer as a mask to etch part of the mask. layer 204 and pad oxide layer 202 to expose the bottom of substrate 200 .

Subsequently, referring to FIG. 2C , using the mask layer 204 as a mask, part of the substrate 200 is removed to form a trench 208 in the substrate 200 . Wherein, the method for removing part of the substrate 200 is, for example, performing an etching process.

Next, referring to FIG. 2D , a dielectric layer 210 is formed on the substrate 200 to fill the trench 208 . Wherein, the material of the dielectric layer 210 is, for example, silicon oxide, and its forming method is, for example, chemical vapor deposition (CVD).

Afterwards, referring to FIG. 2E , a main grinding step is performed to remove a part of the dielectric layer 210 , and the preset thickness of the removed dielectric layer 210 is related to the process margin and does not need to be particularly limited. The above-mentioned main polishing step is the same as the general chemical mechanical polishing process, which provides a polishing liquid and performs it at a polishing speed. Wherein, the grinding solution may be, for example, a high-selectivity grinding solution, which is, for example, a solution containing cerium oxide.

Next, please refer to FIG. 2F , after the main polishing step, an auxiliary polishing step is performed to remove part of the dielectric layer 210 a and part of the mask layer 204 . The auxiliary grinding step is to provide grinding liquid for a period of time (T ₁ ), and no grinding is performed at this time. Then, within a time (T ₂ ), add a solvent and grind at a grinding speed. Wherein, the above-mentioned polishing solution may be the same as that used in the main grinding step, for example, a high-selectivity polishing solution, such as a solution containing cerium oxide, is used.

The above-mentioned time (T ₁ ) for providing the polishing liquid is, for example, between 0 and 20 seconds, and the time for adding the solvent (T ₂ ) is, for example, between 2 and 20 seconds. Wherein, the distribution of the time (T ₁ , T ₂ ) mentioned above is related to the process margin, and can be adjusted according to different process margins, without any special limitation.

Afterwards, referring to FIG. 2G , the mask layer 204 a and the pad oxide layer 202 are removed to form a shallow trench isolation structure 210 b. The method for removing the mask layer 204 a and the pad oxide layer 202 is, for example, performing an isotropic etching process. Since the above-mentioned auxiliary grinding step will remove part of the mask layer material, it can ensure that there will be no residual dielectric layer material on the mask layer 204a, which is beneficial to the subsequent removal process of the mask layer 204a.

In summary, the present invention has at least the following advantages:

1. The composite chemical mechanical polishing method of the present invention does not have the existing problem of over-grinding, which affects the reliability of the process.

2. The manufacturing method of the shallow trench isolation structure of the present invention not only ensures that the material to be polished can be completely polished, but also does not have a dishing phenomenon, and can improve the flatness of the chip surface and the reliability of the process.

3. The compound chemical mechanical polishing method of the present invention can be applied to other semiconductor processes that require chemical mechanical polishing. In addition, the auxiliary grinding step of the present invention can also be applied to the chemical mechanical grinding rework process.

4. The solvent used in the auxiliary grinding step of the present invention is a common chemical solution in the general process, so the cost of the process can be saved.

Although the present invention is disclosed above with preferred embodiments, it is not intended to limit the present invention. Those skilled in the art can make some changes and modifications without departing from the spirit and scope of the present invention, so the protection scope of the present invention It shall prevail as defined in the appended claims.

Claims (12)

1. a combined chemistry mechanical grinding method is suitable for making the structure planarization, comprising:

Lapping liquid is provided,, carries out main grinding steps with first grinding rate; And

Carry out the assisted milling step, so that this structure planarization, wherein this assisted milling step comprises:

At first in the very first time, provide this lapping liquid; And

In second time, add solvent again, and grind with second grinding rate,

Wherein this second grinding rate is less than this first grinding rate.

2. combined chemistry mechanical grinding method as claimed in claim 1, wherein this solvent comprises deionized water.

3. combined chemistry mechanical grinding method as claimed in claim 1, wherein this very first time is between 0 to 20 second.

4. combined chemistry mechanical grinding method as claimed in claim 1, wherein this second time is between 2 to 20 seconds.

5. combined chemistry mechanical grinding method as claimed in claim 1, wherein this lapping liquid comprises the high selectivity lapping liquid.

6. combined chemistry mechanical grinding method as claimed in claim 1, wherein this lapping liquid comprises the solution of oxidation-containing cerium.

7. the manufacture method of a fleet plough groove isolation structure comprises:

Substrate is provided, has been formed with the mask layer of patterning in this substrate, and in this substrate, be formed with at least one groove, and this mask layer exposes this groove;

Forming dielectric layer in this substrate top inserts in this groove;

Carry out main grinding steps, remove this dielectric layer of part;

Carry out the assisted milling step, remove this dielectric layer of part and this mask layer of part, this assisted milling step wherein comprises:

At first in the very first time, provide lapping liquid; And

In second time, add solvent again, and grind, and this grinding rate is less than the grinding rate of this main grinding steps with grinding rate; And

Remove this mask layer.

8. the manufacture method of fleet plough groove isolation structure as claimed in claim 7, wherein this solvent comprises deionized water.

9. the manufacture method of fleet plough groove isolation structure as claimed in claim 7, wherein this very first time is between 0 to 20 second.

10. the manufacture method of fleet plough groove isolation structure as claimed in claim 7, wherein this second time is between 2 to 20 seconds.

11. the manufacture method of fleet plough groove isolation structure as claimed in claim 7, wherein this lapping liquid comprises the high selectivity lapping liquid.

12. the manufacture method of fleet plough groove isolation structure as claimed in claim 7, wherein this lapping liquid comprises the solution of oxidation-containing cerium.

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