KR100323496B1 - Device and Method for Reclaiming of Semiconductor wafer - Google Patents

Abstract

The present invention relates to an apparatus and method for reproducing semiconductor wafers by applying a physical method that suppresses toxic chemical treatments to increase environmental friendliness and to reduce process time and cost. Loading / unloading unit for simultaneously loading / unloading into the apparatus; an air compressor unit for accelerating slurry particles; a sandblast for scanning a wafer while spraying the high pressure fine powder accelerated by the air compressor unit A wafer fixing chuck unit which fixes the loaded wafers and releases the chucking operation when the film layer is removed due to the fracture of the film layer due to the collision of the fine powder sprayed from the sand blasting unit; chucking or chucking of the wafers; To collect or pump fine powders and film debris Pumping / dust collecting unit which is small; is configured to include the the dust and residue particles separation and processing residue / slurry particles processing unit for.

Description

Device and method for reclaiming semiconductor wafers

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the regeneration of semiconductor wafers, and more particularly, to an apparatus and method for regenerating semiconductor wafers by applying a physical method that suppresses toxic chemical treatments to increase environmental friendliness and reduce process time and cost.

In general, to form a semiconductor device, a substrate, that is, a wafer made of a semiconductor material such as silicon is required.

The types of wafers can be broadly divided into prime wafers, test wafers, and dummy wafers. The prime wafers are wafers on which actual devices are formed, and the test wafers are wafers used to monitor each unit process. Say.

In the dummy wafer, the number of prime wafers is used in a batch process, that is, a diffusion process using a furnace or a chemical vapor deposition (CVD) process and an etching process using a chamber. If less than batch size), it means additional wafer.

The reason for using a dummy wafer is to prevent the process unevenness that occurs when the process is carried out by loading fewer wafers than the batch size into the furnace or chamber.

Such a test wafer or a dummy wafer is used again after a series of regeneration processes after a process or use is performed once or several times for a predetermined use.

Of course, even in the case of the prime wafer, if the desired process does not have a desired result after the unit process, it is used again through a series of regeneration process.

This is called "wafer play."

1 is a flow chart showing a wafer regeneration method of the prior art, Figure 2 is a flow chart illustrating the progress of the wafer regeneration process of the prior art.

Conventional wafer regeneration is mainly based on the removal of the deposition layers by chemical treatment, and can be roughly divided into a film stripping step, a lapping step, and a polishing step.

First, the wafer to be regenerated is loaded into the apparatus (100S).

Here, the wafer to be loaded is a wafer on which an oxide film, a nitride film, a poly-Si or a metal film is deposited, and a wafer which has undergone other polishing steps.

Subsequently, it is classified by the state of the deposition layers of the wafer, that is, the type, structure, thickness, etc. of the deposition layers.

Such wafer classification criteria can be further subdivided as high quality is required, but in FIG. 1, the wafer classification criteria are classified into metal layers and insulating layers.

First, in the case of a wafer mainly comprising an oxide film and a nitride film (102S), the deposited films on the wafer surface are etched using HF and H ₃ PO ₄ (103S).

When the metal film or the like is classified into the patterned wafer in the sorting step (104S), the metal film on the surface of the wafer is etched using HNO ₃ / HF (105S).

When the film removal step is completed, the wafer is sorted again to set the lapping removal target (106S).

The wafer sorting here is for inspection of residues, deep scratches, and gap defect fractures in the wafer thickness sorting and film removal steps.

In this inspection, the wafer is deemed seriously required to be wrapped (107S), and after etching and merging the wafer which has been wrapped and the wafer that does not require the lapping step in the inspection process, (108S) A wafer sorting operation is performed to perform the polishing step. (109S)

Here, the wafer sorting operation includes thickness sorting and defect inspection for setting a polishing removal target.

Wafers determined to no longer need the wafer regeneration process by the film stripping step and the lapping step in the classification step are polished and cleaned to complete the wafer regeneration process (110S).

Wafers determined to be necessary again by the film stripping step and the lapping step in the sorting step are put back into the appropriate regeneration step (111S).

If it is determined that the step needs to be performed again in the sorting step performed after the completion of each processing step, the wafer is re-injected into the apparatus until the predetermined standard is reached.

In this prior art wafer regeneration method, the initial film removal step is mainly performed by chemical treatment.

The chemical treatment step is performed by immersing the wafer in a bath using HF / HNO ₃ / CH ₃ COOH mixed acid, H ₂ SO ₄ solution, HF / HNO ₃ , HF, etc., depending on the type of film present on the wafer. The metal film and the pattern layer containing them are removed.

After performing the film removal step, a Quick Dump Rinse (QDR) step is necessarily performed to completely remove residual chemicals.

For example, as shown in FIG. 2, which shows an example of a film removal step, organic removal is performed using H ₂ SO ₄ / H ₂ O ₂ in a ratio of 7: 1 and a QDR step is performed. After removing the chemicals used in the organic removal step, the following steps are performed.

That is, after performing the QDR step, poly / nitride removal is performed using a HNO ₃ / HF ratio of 90: 1, and again, the QDR step is performed to remove the chemical used in the poly / nitride removal step, and then the next step is performed. .

If the oxide film removal step is required as a next step, the oxide film is removed using HF / H ₂ O in a ratio of 1: 1 and the QDR step is performed to remove the chemical used in the oxide film removal step.

As such, after the film removal step by chemical treatment, the QDR process must be performed to remove the chemical used in each step.

This is because the subsequent process in the presence of chemicals may cause another type of chemical reaction, resulting in unexpected residue and impurity layers, which may degrade wafer regeneration characteristics.

In the regeneration of such a prior art semiconductor wafer, there are the following problems.

Due to the chemical treatment in the film removal step present on the wafer, the treatment method is difficult according to the characteristics of the film, and the post-treatment of the chemical used to remove the film increases the complexity of the process.

In particular, expensive chemicals are repeatedly used and cost and process time are consumed in terms of removing used chemicals, and chemical damage to the wafer can be caused.

In addition, HF, one of the chemicals mainly used in the film removal stage, has been increasingly restricted in its application due to tightening regulations on use and emission around the world.

However, in the prior art, there is no method to replace the film removal technique by the chemical treatment, so the wafer regeneration efficiency is not good.

The present invention has been made to solve the problems of the prior art wafer regeneration method, to suppress the chemical treatment of toxic and to apply environmental methods such as blasting (blasting) using slurry particles to increase the environmental friendliness and process It is an object of the present invention to provide an apparatus and method for reproducing a semiconductor wafer which can reduce time and cost.

1 is a flow chart showing a wafer recycling method of the prior art.

2 is a flow chart illustrating the steps of a prior art wafer regeneration process.

3 is a block diagram of a wafer regeneration apparatus according to the present invention;

4 is a block diagram showing an embodiment of a wafer reproducing apparatus according to the present invention;

5A to 5C are exemplary views showing an embodiment of a wafer regeneration method according to the present invention.

6 is a flowchart illustrating a wafer regeneration method according to the present invention.

Explanation of symbols for the main parts of the drawings

31. Air compressor unit 32. Sand blasting unit

33. Wafer fixed chuck unit 34. Wafer loading / unloading unit

35. Pumping / dust collection unit 36. Residue / slurry particle processing unit

The semiconductor wafer reproducing apparatus according to the present invention for achieving the above object is a wafer loading / unloading unit for loading / unloading one wafer or a plurality of wafers into the device at the same time; an air compressor unit for accelerating slurry particles ; Sand blasting unit for scanning the wafer while injecting the high-pressure fine powder accelerated by the air compressor unit; Fixing the loaded wafer and the fracture of the film layer by the collision of the fine powder injected from the sand blasting unit A wafer fixed chuck unit which releases the chucking operation when the film layer is removed; a pumping / dust collection unit configured to collect or pump the fine powder and film debris that have collided in the chucking or chucking state of the wafer; Residue / slurry particle processing unit separating and treating water and particles The semiconductor wafer regeneration method according to the present invention is a dry blasting method when a wafer or a plurality of wafers that have undergone a classification step are loaded at the same time, and (1) the injection conditions are determined according to the state of the film and (2) Accelerating slurry particles, (3) spraying fine powder and scanning the wafer to break up and remove the films present on the wafer surface, and (4) fine powder that has crashed during and after blasting operation. (5) separating and treating the collected residues and particles; Polishing and cleaning the wafers after etching and merging, or repeating the above-described processing.

Hereinafter, an apparatus and method for reproducing a semiconductor wafer according to the present invention will be described in detail with reference to the accompanying drawings.

3 is a block diagram illustrating a configuration of a wafer reproducing apparatus according to the present invention.

Currently, wafers that require regeneration include more than 90% of the oxide, nitride, and polysilicon layers on the surface of dummy wafers and test wafers.

Of course, since the prime wafer is also mainly defective before the final metal wiring forming step, mainly insulating layers such as oxide film, nitride film, and polysilicon layer are the mainstream.

The present invention is a technique for removing the oxide, nitride, and polysilicon layers, which are the main materials present in the wafer, by the physical method of dry blasting by acceleration of slurry particles, rather than toxic chemical treatment.

The film removal by the dry blasting method is to accelerate the particulate powder such as alumina powder (Al ₂ O ₃ ) or SiC to a high pressure and spray on the wafer surface.

The injected fine particles collide with the film layer present on the wafer to physically decompose the film layers.

An apparatus for performing such a dry blasting method is configured as follows.

As shown in FIG. 3, a wafer loading / unloading unit 34 for loading wafers to be regenerated into the apparatus or unloading the wafer which has undergone the regeneration step out of the apparatus, and alumina powder (Al ₂ O ₃ ) Or a sand blasting unit for scanning a wafer while injecting an air compressor unit 31 for accelerating slurry particles such as SiC and high-pressure fine powder accelerated by the air compressor unit 31 through a nozzle. And the wafer loaded by the wafer loading / unloading unit 34 is fixed in a direction perpendicular to the injection angle of the high pressure fine powder injected from the sand blasting unit 32 or maintained at a predetermined angle. When the film layer is broken due to the impact of the fine powder and the film removal is completed, the chucking operation is released to transfer the wafer to the wafer loading / unloading unit 34. In the state where the wafer fixed chuck unit 33 and the wafer are chucked by the wafer fixed chuck unit 33 and the film crushed product which has been crushed by the collision of the fine powder which has been collided with the fine powder are not collected or collected at a position where it is impossible to collect the wafer. A pumping / dusting unit 35 for pumping operation to draw out the crushed matter, and a residue / slurry particle processing unit 36 for separating / treating residues and slurry particles collected by the pumping / dusting unit 35. It is configured to include).

Here, the slurry particles separated by the residue / slurry particle processing unit 36 are reused in the film removal process.

The pumping / dusting unit 35 repeats the dusting and pumping operations even when the wafer is not chucked to discharge the fine powder used to remove the debris or film in the apparatus to the outside of the apparatus.

The sand blasting unit 32 which scans the wafer while injecting the fine powder through the nozzle uses a method of zigzag scanning the wafer or repeatedly moving the nozzle in the X or Y direction.

And the injection amount and injection speed of the high-pressure fine powder to be injected is adjusted according to the film type and film thickness.

In addition to alumina powder (Al ₂ O ₃ ) or SiC, the slurry particles may be any one of carbides, nitrides, oxides, borides and the like having a low cutting efficiency and a Vicker's hardness of 90000 kgf / mm 2 or more, or their It is possible to use mixtures.

As carbides TiC, VC, HfC, ZrC, NbC, WC, TaC, Mo ₂ C, Cr ₃ C ₂ , W ₂ C, B ₄ C, As nitrides TiN, VN, HfN, ZrN, NbN, BN, AlN, Si ₃ N ₄ , CrN, BeO, TiO ₂ , ZrO ₂ , SiO ₂ , CrO ₂ , Cr ₂ O ₂ as oxides, TiB ₂ , ZrB ₂ , HfB ₂ , TaB ₂ , MoB ₂ , CrB ₂ , MoB, Any one of NbB, UB ₂ , MoB _2, etc., or a mixture thereof may be used to enhance the effect of breaking the films on the wafer.

In the operation of injecting the slurry particles onto the wafer, it is appropriate to spray with a pressure of 0.2 kg / cm 2 or more.

In addition, in order to reduce the damage to the wafer in the film removal step, the smaller the average diameter of the slurry particles is better, but in order to shorten the process time and improve the roughness of the wafer, the average diameter of the slurry particles is preferably 2 μm to 30 μm.

When the film removing step is performed under such conditions, since the insulating film and the semiconductor layer formed on the wafer are formed to a thickness of about 1 μm or less, the film layer is easily removed by the collision of slurry particles having a diameter larger than the film thickness.

When the fine powder is injected onto the wafer, the fine powder impingement surface of the wafer may face downward, and the fine powder may be injected onto the wafer from below.

This can easily remove the fine powder used for the crush or film removal from the wafer and increase the film crushing efficiency.

Such a film removing process may be performed by adjusting the loading / unloading unit 34 and the wafer fixing chuck unit 33 to arrange a plurality of wafers horizontally, thereby shortening the process time.

In addition, when there is a film or residue to be removed at the side of the wafer, it is also possible to perform a film removal process after stacking and loading a plurality of wafers.

The wafer fixing chuck unit 33 may fix the wafer by using a bar pressure, and adhere to a temperature of 0 ° C. or more and 50 ° C. or less and heat the sheet at a temperature of 80 ° C. to 200 ° C. Can be used to fix the wafer.

As another method, it may be fixed to the back surface of the wafer by using a wax having an adhesive force of a predetermined viscosity or more.

The actual configuration of the wafer reproducing apparatus and the regeneration operation method using the same according to the present invention will be described below.

4 is a block diagram showing an embodiment of a wafer regeneration apparatus according to the present invention, Figures 5a to 5c is an exemplary view showing an embodiment of a wafer regeneration method according to the present invention.

The wafer recycling apparatus according to the present invention can be constructed as follows.

First, a wafer is sprayed while spraying high-pressure fine powder, which is composed of a main body 46 of a regeneration device in which a sand blasting operation takes place and an arbitrary position within the main body 46 and accelerated by the air compressor unit 31. A sand blasting unit 32 for scanning, an accelerated slurry particle supply line 44 connecting between the sand blasting unit 32 and the air compressor unit 31, and a wafer inside the main body 46. Wafer fixation chuck unit 33 for fixing 45 and a hopper form at the lower side of the main body 46 to collide with fine powder and film crushed material in the chucking or chucking state of the wafer 45. A cyclone 41 for collecting dust or a pumping operation, and a pumping / dusting unit 35 connected to the pumping / dusting unit 35 through a crushed material / slurry particle discharge line 43 to sort crushed material and slurry particles; , The cycle A fine powder collecting means 42 for collecting and supplying the slurry particles selected and connected to the lower side of the 41 to the air compressor unit 31, and the residues such as the crushed matter selected by the cyclone 41 It consists of a residue / slurry particle processing unit 36 to be treated.

The wafer recycling apparatus according to the embodiment of the present invention configured as described above

When the wafer 45 is fixed by the wafer fixing chuck unit 33, the accelerated fine powder is injected into the main body 46 through the spray nozzle of the sand blasting unit 32.

The sprayed fine powder collides with the film layers of the wafer 45 and breaks the layers to separate the wafer 45 and the film layers.

The fine powder which has collided with the film layers of the wafer 45 is discharged to the cyclone 41 by the pumping / dust collection unit 35 through the crushed / slurry particle discharge line 43.

Then, the film shredded by the cyclone 41 and the reusable fine powder are sorted and the reusable fine powder is collected by the fine powder collecting means 42 and is an air compressor unit which is a means for accelerating and supplying fine powder. And the film shreds are sent to a residue / slurry particle processing unit 36.

The wafer regeneration operation using the wafer regeneration apparatus according to the embodiment of the present invention configured as described above is performed in the following manner.

First, FIG. 5A illustrates that a plurality of wafers 45 are arranged horizontally using the wafer fixing chuck unit 33 to simultaneously perform a film removing step, in which the spray slurry 47 is vertical or fixed to the lower wafer surface. It is to be sprayed with.

This is done by moving the sand blasting unit 32 in the most common manner to repeatedly scan the entire surface of the wafer 45 to remove film layers.

Alternatively, as shown in FIG. 5B, the wafer 45 is fixed to the lower side of the wafer fixing chuck unit 33 so as to face downward on the front surface of the wafer 45.

This is to spray the fine powder from the bottom upwards to facilitate the removal of film debris can shorten the process time and increase the film removal effect.

The method of FIG. 5C is to remove the film layers deposited on the side of the wafer 45. After stacking a plurality of wafers 45 and fixing them with a protective plate 48, the powders are removed by spraying fine powder. will be.

The film removing step in this manner may be omitted when there is no object to be removed on the side of the wafer 45.

In the case of the film removal step of the above-described manner, when the film layer is thick or the metal or the metal compound of different materials, it is also possible to combine the etching step with the chemical liquid in addition to the injection of the fine powder.

As described above, when the wafer regeneration method using the wafer regeneration apparatus according to the present invention was performed under the following process conditions, it was found that the wafer regeneration efficiency was extremely good.

In other words, using a 12-inch silicon wafer on which thin films such as titanium nitride, aluminum, alumina, tungsten, and silicon nitride are deposited, the air pressure is 0.5kg / cm 2, the distance between the spray nozzle and the wafer is 30 mm, and the spray nozzle is moved. The film layers on the wafer were removed by using a speed of 30 m / min, a work movement speed of 200 mm / min, and slurry particles using Howart Arandam # 1500 (alumina powder), and the wafer was removed to remove the film layers on the wafer side. 10 sheets were laminated to remove the film layers on the side in the same manner as in FIG. 5C.

When removing the wafer side film layer, the air pressure was 0.5 kg / cm 2, the nozzle distance was 30 mm, the substrate rotation speed was 10 rpm, the process time was 120 seconds, and the slurry particles were made of Howat Arandam # 1500 (alumina powder). Film removal steps were carried out.

As a result, the wafer surface roughness after film removal is Rmax 0.8 mu m in the method of FIG. 5A, and the wafer surface roughness is Rmax 0.5 mu m in the method of FIG. 5B, and the film removal efficiency is good and the film layer is uniformly spread over the entire wafer surface in any way. Were removed.

The wafer regeneration method using the wafer regeneration device according to the present invention will be described in detail as follows.

6 is a flowchart illustrating a wafer regeneration method according to the present invention.

First, the wafer to be reclaimed is loaded into the apparatus using the wafer loading / unloading unit 34. (600S)

Here, the wafer to be loaded is a wafer on which an oxide film, a nitride film, a poly-Si or a metal film is deposited, and a wafer which has undergone other polishing steps.

Subsequently, it is classified by the state of the deposition layers of the wafer, that is, the type, structure, thickness, and the like of the deposition layers.

Such wafer classification criteria can be further subdivided as the demand for high quality is largely classified into metal films and insulating films.

First, in the case of a wafer mainly comprising an oxide film, a nitride film, and a polysilicon layer (602S), the slurry particles are accelerated by determining the injection amount, the injection speed, and the scanning speed of the slurry to be sprayed according to the film state using a dry blasting apparatus. After spraying, the film is crushed and removed from the wafer surface.

After the film crushing operation, a process of increasing the surface uniformity of the wafer is performed by adjusting the spraying amount, the spraying speed, and the scanning speed of the slurry to be sprayed again (603S).

The collided fine powder and film shreds generated during the film removal step are collected or pumped, and the collected residue and particles are separated and processed.

When the metal film or the like is classified into the patterned wafer in the sorting step (604S), the metal film on the surface of the wafer is etched using HNO3 / HF (605S).

Subsequently, the wafer which has been etched with the metal film is inspected, and wafer sorting for setting a lapping removal target is performed (606S).

The wafer classification here is carried out for inspection of residues, deep scratches and crevice defects during wafer thickness classification and etching.

In this inspection process, the wafer is deemed seriously required to be wrapped (607S), and the wafer which has been wrapped and the wafer which does not require the lapping step in the inspection process and the dry blasting process are etched. And the wafer sorting process to perform the polishing step (608S) after merging (609S).

Here, the wafer sorting operation includes thickness sorting and defect inspection for setting a polishing removal target.

Wafers determined to no longer require the wafer regeneration process by the film stripping step and the lapping step in the classification step are polished and cleaned to complete the wafer regeneration process (610S).

Wafers determined to be needed again by the film stripping step and the lapping step in the sorting step are put back into the appropriate regeneration step (611S).

If it is determined that the step is to be performed again in the classification step that is performed after the completion of each processing step, it is re-injected until a certain criterion is reached.

Such a method of regenerating a semiconductor wafer according to the present invention shortens the process cycle by removing a film such as an oxide film, a nitride film, or a polysilicon layer, which is 90% or more of the material present on the wafer surface, by a physical method rather than a chemical treatment. Prevents chemical damage from damage.

As such, the slurry used in the wafer regeneration method according to the present invention, the film to be removed, and the method of spraying fine powder may be modified and improved at the level of those skilled in the art.

The semiconductor wafer recycling apparatus and method according to the present invention has the following effects.

Dry blasting by spraying fine powder without chemical treatment in the film removal step present on the wafer is used to reduce process cycles and reduce chemical damage to the wafer.

This has the effect of increasing the wafer regeneration efficiency.

In addition, since it does not use a large amount of DI and various chemicals, it is advantageous in terms of cost and process time reduction.

Another effect is that it does not use chemicals, which are mainly used in the film removal step, and thus has high environmental friendliness and stability and reduces the burden on waste acid treatment.

Claims (6)

Claims [1] An apparatus for regenerating and surface processing a wafer by removing stacks formed on the wafer. A wafer loading / unloading unit for loading / unloading one wafer or a plurality of wafers into the device at the same time; An air compressor unit for accelerating slurry particles; A sand blasting unit scanning a wafer while injecting the high pressure fine powder accelerated by the air compressor unit; A wafer fixing chuck unit which fixes the loaded wafers and releases the chucking operation when the film layer is broken due to the collision of the fine powder sprayed from the sand blasting unit and the film layer is removed; A pumping / dusting unit configured to collect or pump the fine powder and the film crushed material which have been collided in the chucking or chucking state of the wafer; And a residue / slurry particle processing unit for separating and treating the collected residues and particles. The semiconductor wafer reproducing apparatus according to claim 1, wherein the sand blasting unit varies the injection amount, the spraying speed, the spraying angle, and the wafer scanning speed of the fine powder according to the state of the film present on the wafer. The semiconductor wafer regeneration apparatus according to claim 1, wherein the slurry particles use any one or a mixture of carbides, nitrides, oxides, borides, and the like having a Vicker's hardness of 90,000 kgf / mm 2 or more. When a wafer or a plurality of wafers that have been sorted are loaded at the same time, dry blasting is performed. (1) Determine the spraying conditions according to the state of the film, (2) after accelerating slurry particles, (3) by spraying the fine powder and scanning the wafer to break up and remove the film present on the surface of the wafer, (4) Collecting or pumping fine powders and crushed particles that have crashed during and after blasting operation, (5) separating and treating the collected residues and particles; Polishing and cleaning the wafers after etching and merging or repeating the above-described processing. The method of claim 4, wherein the wafer classification is classified into a wafer including a metal film and a wafer not containing a metal film. Before polishing and cleaning wafers containing metal films (1) chemical treatment to etch the metal film on the wafer surface; (2) Inspect the wafer after the metal film has been etched and classify the wafer for setting the lapping removal target, (3) A method of regenerating a semiconductor wafer, characterized in that the step of selectively lapping the wafer requiring lapping is performed. 6. The method of claim 4 or 5, wherein the material layer collided with the fine powder and crushed in the wafer not including the metal film comprises an oxide film, a nitride film, or a polysilicon layer.