CN1245740C - Chemical Mechanical Polishing Process - Google Patents

Abstract

A chemical mechanical polishing process uses a polishing agent containing silicon dioxide polishing particles to polish a layer to be polished on a substrate, and adds a hydroxyl solution capable of reducing the polishing particles before the polishing step is finished so as to prevent the surface of a wafer from being scratched.

Description

Chemical Mechanical Polishing Process

technical field

The present invention relates to a semiconductor process, and in particular to a chemical mechanical polishing (CMP) process.

Background technique

At present, the chemical mechanical grinding process has been widely used in the planarizing or smoothing technology of the insulating layer surface. It mainly uses the mechanical grinding principle similar to "sharpening a knife" and cooperates with appropriate chemical additives. (reagent), a planarization technology that "smooths" the contours of the wafer surface with ups and downs. In the basic chemical mechanical polishing process, the wafer to be polished is placed in a chemical mechanical polishing machine, and chemical additives are added during grinding, the so-called abrasive (slurry), which contains abrasive grains with extremely high hardness. .

However, although the above-mentioned chemical mechanical polishing process can keep the removal rate (removing rate) stable during operation, it is unavoidable that after the polishing is completed, the exposed wafer surface is covered with abrasive particles because the polished layer has been removed. Scratch (scratch), especially when the layer scheduled to be removed by grinding is an insulating layer, the insulating layer removed at the initial stage of grinding will also become residual particles, increasing the risk of scratching the wafer surface at the later stage of grinding.

Contents of the invention

Therefore, the object of the present invention is to provide a chemical mechanical polishing process to avoid scratches on the wafer surface during the chemical mechanical polishing process.

Another object of the present invention is to provide a chemical mechanical polishing process for reducing the size of abrasive grains in the later stage of the polishing process.

Another object of the present invention is to provide a chemical mechanical polishing process, so as to avoid premature reduction of the size of the abrasive grains, so that the grinding cannot be completed within a predetermined time, or even the grinding effect cannot be achieved.

According to above-mentioned and other object, the present invention proposes a kind of chemical mechanical polishing process, is to use the polishing agent (polishing agent) that contains silica particle (silica particle) to grind the layer to be polished on the substrate, and finish before the grinding step A hydroxide solution that can reduce abrasive particles, such as potassium hydroxide (chemical formula: KOH) solution, is added to avoid scratches on the wafer surface.

The present invention is by providing the solution that can reduce abrasive grain, when for example abrasive grain is silicon dioxide particle, then can utilize hydroxide solution as the solution that can reduce abrasive grain, so that it produces hydrolysis with silicon dioxide, thereby reduces The size of the silica particles and will therefore change the pH of the abrasive. The present invention can also reduce the probability of the surface of the wafer being scratched because the size of the abrasive particles can be reduced. Moreover, it is best to add the solution that can reduce the size of the abrasive grains before the grinding process is almost completed, so as to avoid premature reduction in the size of the abrasive grains due to too early addition, and the grinding cannot be completed within the predetermined time, or even the grinding effect cannot be achieved .

Description of drawings

Fig. 1 is a chemical mechanical polishing process step diagram according to a first embodiment of the present invention;

FIG. 2 is a schematic diagram of chemical mechanical polishing process steps according to a second embodiment of the present invention.

100, 200: Provide wafers to be ground

110: grinding wafer

120: Add a solution that can reduce the size of the abrasive particles

210: Put the wafer into the chemical mechanical polishing machine

220: Grinding Wafers Using a Chemical Mechanical Grinding Machine

230: add hydroxide solution

Detailed ways

first embodiment

FIG. 1 is a step diagram of a chemical mechanical polishing (CMP) process according to a first embodiment of the present invention.

Referring to FIG. 1 , in step 100 , a wafer to be polished is provided. Then, in step 110, the wafer is ground, wherein the slurry used for grinding the wafer contains abrasive particles, such as silicon dioxide (silica particle) abrasive particles.

Then, in step 120, a solution that can reduce the abrasive grain is added to reduce the size of the abrasive grain, thereby reducing the probability of the wafer surface being scratched, wherein the solution that can reduce the abrasive grain is, for example, potassium hydroxide (KOH) solution; for example For example, when the concentration of the added potassium hydroxide solution is about 1 volume molar concentration, the pH value of the abrasive will gradually change from 10 to about 12, and the particle size of the abrasive particles will also be reduced from 130 nanometers. Moreover, in order to obtain the best grinding effect, the operation time is preferably between 10-30 seconds, and the flow rate of the potassium hydroxide solution is approximately between 10-500 cubic centimeters per minute.

In addition, the time of adding the solution that can reduce the abrasive particles needs to be controlled after step 110 and before the completion, preferably before the grinding process is nearly completed, so as to avoid premature reduction in the size of the abrasive particles due to adding the solution that can reduce the abrasive particles too early , and the grinding cannot be completed within the predetermined time, or even the grinding effect cannot be achieved.

After grinding, the surface of the wafer can be easily inspected by an optical microscope (OM) or other instruments, and it is known that the wafer is flat and has fewer defects.

second embodiment

FIG. 2 is a step diagram of a chemical mechanical polishing process according to a second embodiment of the present invention, mainly using a chemical mechanical polishing machine for polishing.

Referring to FIG. 2, in step 200, a wafer to be ground is provided. Then, in step 210, the wafer is placed into a chemical mechanical polishing machine station to prepare for polishing. Subsequently, in step 220, the wafer is ground by using a chemical mechanical polishing machine, wherein the abrasive used for grinding the wafer contains silicon dioxide abrasive grains. Then, in step 230, a hydroxide solution is added, wherein the hydroxide solution is, for example, potassium hydroxide (KOH) solution; for example, when the concentration of the potassium hydroxide solution added is about 1 volume molar concentration, the abrasive The pH value will gradually change to greater than 10, and the particle size of the abrasive particles will also decrease. Moreover, in order to obtain the best grinding effect, the operation time is preferably between 10-30 seconds, and the flow rate of the potassium hydroxide solution is approximately between 10-500 cubic centimeters per minute. Furthermore, the time for adding the hydroxide solution should be controlled after step 220 and before completion, preferably before the grinding process is nearly completed.

In summary, the features of the present invention include:

1. The present invention reduces the size of the silicon dioxide abrasive grains by adding a solution that can reduce the abrasive grains, so as to reduce the probability of the wafer surface being scratched.

2. Since the present invention adds the solution that can reduce the abrasive grains after a period of time after the start of grinding, it can avoid adding the solution that can reduce the abrasive grains too early, which will cause the size of the abrasive grains to shrink early, so that the size of the abrasive grains cannot be reduced within the predetermined time. Grinding is complete, or even the effect of grinding cannot be achieved.

Claims (19)

1. a chemical mechanical milling tech is characterized in that, this technology comprises:

A wafer to be ground is provided;

This wafer is inserted a work-table of chemicomechanical grinding mill;

Utilize this work-table of chemicomechanical grinding mill to grind this wafer, the All Time that wherein grinds this wafer is a very first time; And

One second time after beginning to grind this wafer adds a hydroxy solution, and wherein this second time is shorter than this very first time.

2. plant on the cmp as claimed in claim 1, it is characterized in that, more comprise and use a grinding agent that contains the silicon dioxide abrasive grains.

3. chemical mechanical milling tech as claimed in claim 1 is characterized in that, this hydroxy solution comprises a potassium hydroxide solution.

4. chemical mechanical milling tech as claimed in claim 3 is characterized in that, the flow velocity of this potassium hydroxide solution is between 10～500 cubic centimetres of per minutes.

5. chemical mechanical milling tech as claimed in claim 3 is characterized in that the concentration of this potassium hydroxide solution is about 1 molarity.

6. chemical mechanical milling tech as claimed in claim 3 is characterized in that the operating time of this potassium hydroxide solution is between 10～30 seconds.

7. a chemical mechanical milling tech is characterized in that, this technology uses a grinding agent that contains an abrasive grains to comprise:

One wafer is provided;

Use this grinding agent to grind this wafer, the All Time that wherein grinds this wafer is a very first time; And

One second time after beginning to grind this wafer adds a hydroxy solution, and wherein this second time is shorter than this very first time.

8. chemical mechanical milling tech as claimed in claim 7 is characterized in that this abrasive grains comprises silica dioxide granule.

9. chemical mechanical milling tech as claimed in claim 7 is characterized in that, this hydroxy solution comprises a potassium hydroxide solution.

10. chemical mechanical milling tech as claimed in claim 9 is characterized in that, the flow velocity of this potassium hydroxide solution is between 10～500 cubic centimetres of per minutes.

11. chemical mechanical milling tech as claimed in claim 9 is characterized in that, the concentration of this potassium hydroxide solution is about 1 molarity.

12. chemical mechanical milling tech as claimed in claim 9 is characterized in that, the operating time of this potassium hydroxide solution is between 10～30 seconds.

13. a chemical mechanical milling tech is suitable for removing one on the wafer and treats the mill layer in a set time, it is characterized in that this technology comprises:

Grind this wafer, this treats the mill layer to remove part; And

In near this set time the time, add a hydroxy solution.

14. chemical mechanical milling tech as claimed in claim 13 is characterized in that, this can treat that the mill layer comprises insulating barrier.

15. chemical mechanical milling tech as claimed in claim 13 is characterized in that, more comprises using a grinding agent that contains the silicon dioxide abrasive grains.

16. chemical mechanical milling tech as claimed in claim 13 is characterized in that, this hydroxy solution comprises a potassium hydroxide solution.

17. chemical mechanical milling tech as claimed in claim 16 is characterized in that, the flow velocity of this potassium hydroxide solution is between 10～500 cubic centimetres of per minutes.

18. chemical mechanical milling tech as claimed in claim 16 is characterized in that, the concentration of this potassium hydroxide solution is about 1 molarity.

19. chemical mechanical milling tech as claimed in claim 16 is characterized in that, the operating time of this potassium hydroxide solution is between 10～30 seconds.

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