CN112959211B

CN112959211B - Wafer processing apparatus and processing method

Info

Publication number: CN112959211B
Application number: CN202110196093.XA
Authority: CN
Inventors: 陈鹏; 周厚德; 苗健; 李明亮
Original assignee: Yangtze Memory Technologies Co Ltd
Current assignee: Yangtze Memory Technologies Co Ltd
Priority date: 2021-02-22
Filing date: 2021-02-22
Publication date: 2021-12-31
Anticipated expiration: 2041-02-22
Also published as: CN112959211A

Abstract

The application provides a wafer processing apparatus and a processing method. The processing apparatus includes a wafer placing section configured to place a wafer, wherein the wafer has an irregular edge portion; an auxiliary frame configured to form a groove with a surface of the irregular edge portion of the wafer; and a filler addition part configured to add a filler in the groove. By filling the irregular edge of the wafer by using the processing device and then performing thinning processing, the difficulty of the wafer thinning process can be greatly reduced, the product percent of pass is increased, and the production cost is reduced.

Description

Wafer processing apparatus and processing method

Technical Field

The present application relates to the field of semiconductor manufacturing, and more particularly, to wafer processing apparatus and methods.

Background

In the field of semiconductor manufacturing, after a device structure is prepared on the front surface of a wafer, thinning processing needs to be performed on the back surface of the wafer. The thinned wafer is beneficial to ultrathin packaging, effective light transmission, better heat dissipation, better electrical performance and the like. Therefore, the wafer thinning process becomes an important process in the semiconductor manufacturing field.

Conventional wafer packaging requires thinning the wafer to hundreds or tens of microns. In the process of developing the 3D NAND process, various irregular shapes, for example, steps, frequently appear on the edge of the wafer due to process requirements. The process difficulty of thinning the wafer with the irregular edge is far higher than that of thinning the wafer with the conventional edge, and the damage rate or the splintering rate of the wafer is extremely high. Fig. 1 is a schematic diagram of thinning a wafer with irregular edges by using the prior art. As shown in fig. 1, the wafer 100 includes an active layer 110 and a base layer 120, wherein an edge portion 130 of the base layer 120 is a fragile portion. When the grinding wheel 140 is used to thin the wafer 100, a special glue layer 150, such as an ultra-thick glue, an ultraviolet-sensitive glue, etc., is required, which requires a high thinning process and almost doubles the cost. In addition, the adoption of the glue layer can cause the problems of wafer shaking, glue residue, vacuum leakage of the workbench and the like, so that a machine table needs to be modified.

Currently, in the process of thinning the wafer with irregular edge, the following three methods are generally adopted to reduce the cracking rate: firstly, a mechanical cutter edge cutting method is adopted, namely, the whole step edge is eliminated through a grinding cutter, and then the wafer is thinned through a common method, and the method needs a special cutting machine and upgrades a thinning machine, so that the thinning speed is low, and the production cost is high; secondly, the pre-cutting method is to pre-cut the wafer body first, and isolate the cracks possibly generated at the edge part of the wafer, so as to reduce the loss of the active layer as much as possible, the method has complex process, needs to adopt a special adhesive tape, cannot eliminate edge splinters by 100 percent, has high cost and is not suitable for an ultrathin process; thirdly, the laser circular cutting method, namely, firstly, the circular cutting is generated on the inner edge part of the wafer by utilizing the laser to isolate the cracks which may be generated, the method also needs a special machine and an adhesive tape, the production cost is high, and the circular cutting remaining part still causes certain risks in the thinning process.

Therefore, further reducing the cracking rate during the thinning process of the irregular-edge wafer and simultaneously reducing the production cost and the process difficulty are the problems which are urgently needed to be solved at present.

Disclosure of Invention

The present application provides a wafer processing apparatus and a processing method that can at least partially solve the above-mentioned problems in the prior art.

In one aspect of the present application, a wafer processing apparatus is provided. The apparatus may include: a wafer placing section configured to place a wafer to be processed, wherein the wafer has an irregular edge portion; an auxiliary frame configured to form a groove with a surface of the irregular edge portion of the wafer; and a filler addition part configured to add a filler in the groove. In one embodiment, the filler addition part may be configured such that an upper surface of the filler is flush with an upper surface of the wafer. In one embodiment, the apparatus may further comprise a curing unit. The curing unit may be configured to perform a curing process on the filler in the groove. In one embodiment, the apparatus may further include a thinning unit. The thinning unit may be configured to perform thinning processing on the wafer to which the filler is added. In one embodiment, the sub-frame may have a ring shape to surround the wafer. In one embodiment, the auxiliary frame is adjustable in shape and size to be in abutting contact with a surface of the irregular edge portion of the wafer to form the recess. In one embodiment, the filler may comprise a resin. In one embodiment, the curing unit may be configured to at least one of the following curing treatments of the filling: exposure curing treatment, heating curing treatment and normal temperature curing treatment. In one embodiment, the apparatus may further include a filler removal unit. The filler removing unit may be configured to remove the filler after the thinning process. In one embodiment, the filler removing unit may be configured to remove the filler through a cleaning process and/or a heat treatment process. In one embodiment, the apparatus may further comprise a transfer unit. The transfer unit may be configured to transfer the wafer between at least two of the wafer placing section, the curing unit, and the thinning unit.

In another aspect of the present application, a method of processing a wafer is provided, wherein the wafer to be processed has an irregular edge portion. The method can comprise the following steps: filling the irregular edge part of the wafer with filler; curing the filler; and thinning the wafer after the curing treatment. In one embodiment, the step of filling the irregular edge portion of the wafer with the filler may include: arranging a frame surrounding the wafer, wherein a groove is formed between the frame and the surface of the irregular edge part of the wafer; and adding a filler in the groove to fill the irregular edge part of the wafer. Wherein the step of adding a filler in the recess to fill the irregular edge portion of the wafer may include forming the filler such that an upper surface thereof is flush with an upper surface of the wafer. In one embodiment, the filler may comprise a resin. In one embodiment, the curing process may include an exposure curing process, a heating curing process, and/or an ambient curing process. In one embodiment, after the thinning step, removing the filler may be further included. In one embodiment, the step of removing the filler may include removing the filler using a cleaning process and/or a heat treatment process.

According to the wafer processing device and the processing method, the irregular edge of the wafer is remolded by the filler, and then the wafer is thinned, so that the production cost can be reduced, and the product percent of pass is improved. The processing method is suitable for irregular wafers with different shapes and sizes, and a special glue layer is not needed, so that the difficulty of the thinning process of the irregular edge wafer is greatly reduced.

Drawings

Other features, objects, and advantages of the present application will become more apparent upon reading of the following detailed description of non-limiting embodiments thereof, with reference to the accompanying drawings. In the drawings:

FIG. 1 is a schematic diagram of thinning a wafer with irregular edges according to the prior art;

FIG. 2 is a schematic view of a wafer processing apparatus according to an exemplary embodiment of the present application;

FIGS. 3A and 3B are schematic diagrams of filling a wafer edge according to an exemplary embodiment of the present application;

FIGS. 4A and 4B are cross-sectional views of a wafer after edge filling and curing of the wafer is completed, according to an exemplary embodiment of the present application; and

fig. 5 is a flow chart of wafer processing according to an example embodiment of the present application.

Detailed Description

The present application will hereinafter be described in detail with reference to the accompanying drawings, and the exemplary embodiments mentioned herein are only for explaining the present application and do not limit the scope of the present application.

It will be understood that expressions such as "including", "comprising", "having", "including" and/or "comprising", and the like, are open rather than closed expressions in this specification which indicate the presence of stated features but do not preclude the presence or addition of one or more other features and/or groups thereof. Furthermore, when a statement such as "any of" appears after a list of listed features, it modifies that entire list of features, rather than just individual features in the list. The expression "and/or" includes any and all combinations of one or more of the associated listed items. Furthermore, when describing embodiments of the present application, the use of "may" mean "one or more embodiments of the present application. As used herein, the terms "approximately," "about," and the like are used as approximations, not as degrees of expression, and are intended to account for inherent deviations in measured or calculated values that will be recognized by those of ordinary skill in the art.

Unless otherwise defined, all terms (including engineering and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Furthermore, unless otherwise indicated herein, words defined in commonly used dictionaries should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense.

In addition, the embodiments and features of the embodiments in the present application may be combined with each other without conflict. Further, unless explicitly defined or contradicted by context, the specific steps included in the methods described herein are not necessarily limited to the order described, but can be performed in any order or in parallel. The present application will be described in detail below with reference to the accompanying drawings in conjunction with embodiments.

Fig. 2 is a schematic view of a wafer processing apparatus 200 according to an exemplary embodiment of the present application. In this embodiment, the wafer processing apparatus 200 may include: a wafer placing section 10, an auxiliary frame 20, and a filler adding section 30. According to an exemplary embodiment, the wafer processing apparatus 200 may further include a curing unit 40 and a thinning unit 50.

Specifically, the wafer placing section 10 is used to place or fix a wafer to be thinned. Alternatively, the wafer placing section 10 may be provided with a holder or a suction cup for holding the wafer to be thinned. Alternatively, the wafer placing section 10 may be provided with a vacuum function. The wafer to be thinned may include an active layer in which, but not limited to, memory arrays and/or peripheral circuitry may be formed, and a base layer, which may be, but not limited to, a semiconductor material such as monocrystalline silicon.

The sub-frame 20 serves to form a groove with the surface of the irregular edge portion of the wafer. The recess may be used to add filler in a subsequent process to reshape the irregular edge portion of the wafer. The sub-frame 20 may be fixed while being in close contact with the surface of the wafer. Alternatively, the sub-frame 20 may be a ring frame, and the shape and size thereof can be adjusted so as to be suitable for wafers of different shapes and sizes. Alternatively, the sub-frame 20 may be movable so as to be aligned with and brought into close contact with the wafer. Optionally, the sub-frame 20 may be removable to allow for replacement of frames of different shapes, sizes and materials to accommodate different wafers and different fill requirements.

The filler adding part 30 is used to add filler between the sub-frame 20 and the wafer to be thinned. The filler may be injected into the groove formed between the sub-frame 20 and the surface of the irregular edge portion of the wafer through a pipe. The filler addition part 30 may be, but is not limited to, a glue gun having a pipe. The speed, time, etc. of the filler addition by the filler adding portion 30 can be controlled so that the upper surface of the filler is eventually flush with the upper surface of the wafer to be thinned. Optionally, the height difference between the upper surface of the filler and the upper surface of the wafer may be selected according to the volume change of the filler after the subsequent curing process.

The filler may be, but is not limited to, a resin. Optionally, the filler is soluble in a particular liquid to increase the filling capacity of the filler. The filler may also have a certain viscosity to provide good adhesion between the filler and the surface of the wafer after the subsequent curing process. The good bonding fastness can ensure that the filler is not easy to fall off in the subsequent thinning treatment process, and meanwhile, the filler plays a role in protecting irregular edge parts (generally with metal interconnection structures) of the wafer. In particular embodiments, the edge of the wafer to be thinned may take on various shapes, i.e., not limited to a step shape, and thus, the filler may fill the gap between the wafer surface and the auxiliary frame 20 while surrounding the bump on the wafer surface.

According to an exemplary embodiment of the present application, the wafer processing apparatus 200 may further include a curing unit 40. After the filling process, the curing unit 40 may perform a curing process on the filler to increase the strength of the filler and the adhesion fastness with the surface of the wafer. Alternatively, the curing unit 40 may perform an exposure curing process on the filler, for example, the filler may be irradiated with ultraviolet light of an appropriate wavelength. Alternatively, the curing unit 40 may perform a heat curing process on the filler, for example, when the filler is a resin material, the filler may be subjected to a baking process at a temperature of 120 ℃ to 400 ℃, and the duration of the baking may be 1 to 10 minutes. Alternatively, the curing unit 40 may perform an ambient curing process on the filler, for example, an air drying process on the filler using an air blower. The selection of different curing methods depends on the requirements of different filling materials and different wafers, and the curing time can be selected according to the curing method and the filling materials. After the curing process, the upper surface of the filler may be flush with the upper surface of the wafer to be thinned. Optionally, the height difference between the upper surface of the filler and the upper surface of the wafer is in the micrometer level to meet the process requirement. After the curing process, the sub-frame 20 may be removed from the wafer surface.

According to an exemplary embodiment of the present application, the wafer processing apparatus 200 may further include a thinning unit 50 for performing a thinning process on the edge-filled wafer after the curing process. The thinning unit 50 may thin the wafer using a grinding process, a chemical mechanical polishing process, and/or an etching process. In one embodiment, the thinning unit 50 may perform twice thinning on the wafer by using a grinding process and a chemical mechanical polishing process. In the first thinning process, a grinding process may be employed. Since the thinning speed of the grinding process is fast, that is, the process efficiency is high, the total time required for thinning can be reduced, the process efficiency is improved, and the cost is reduced by using the grinding process at the beginning of thinning. Optionally, thinning of the unfilled back side of the wafer is performed by a grinding process, thinning the wafer thickness to 30 to 400 μm. In the second thinning process, a chemical mechanical polishing process may be employed. The chemical mechanical polishing process can more accurately control the thinning amount of the wafer, thereby meeting the requirement of thinning thickness in the process. In another embodiment, the thinning unit 50 may perform twice thinning on the wafer by using a grinding process and a wet etching process. In the first thinning process, a grinding process may be employed to substantially thin the thickness of the wafer to a predetermined thickness, for example, the thickness of the wafer may be thinned to 5 to 10 μm greater than the predetermined thickness. In the second thinning process, a wet etching process may be used to thin the thickness of the wafer to a predetermined thickness. In the thinning process, the filler can not only protect structures such as metal interconnection lines exposed at the edge of the wafer from being damaged, but also reduce or avoid pollution caused by stripping objects formed in the thinning process of the wafer.

Optionally, the processing apparatus 200 may further include a filler removing unit (not shown) for removing the filler from the edge of the wafer after the thinning process. The filler removing unit may remove the filler through a cleaning process and/or a heat treatment process. Optionally, the processing apparatus 200 may further include a transfer unit (not shown) for transferring the wafer between the wafer placing part 10, the curing unit 40, the thinning unit 50, and the filler removing unit.

Fig. 3A and 3B are schematic side and top views, respectively, of filling a wafer edge according to an exemplary embodiment of the present application. As shown in fig. 3, the wafer 300 to be thinned may include an active layer 310 and a base layer 320. Wherein the side of the wafer 300 close to the active layer 310 has an irregular edge, for example, a step shape. The sub-frame 330 may be a ring frame adapted to the wafer 300. The sub-frame 330 may be fixed in close contact with the edge 301 of the surface of the irregular edge portion of the wafer 300 and form an annular groove 340 with the surface 302 of the irregular edge portion of the wafer 300. The upper surface of the sub-frame 330 may be flush with the upper surface of the wafer 300 or higher than the upper surface of the wafer 300. The filler 360 may be injected into the groove 340 through a pipe in the filler adding part 350. The upper surface of the filler 360 may be made substantially flush with the upper surface of the wafer by controlling the implantation speed and the implantation time of the filler 360. After the implantation is completed, the filler 360 is formed into a structure having a stable annular solid shape, i.e., reshaping of the irregular edge portion of the wafer 300 is substantially completed.

Fig. 4A and 4B are schematic side views of a wafer after edge filling and curing is completed according to an exemplary embodiment of the present application. As shown in fig. 4A, the wafer 400 may include an active layer 410 and a base layer 420. Wherein a side of the wafer 400 near the active layer 410 may have an irregular edge in a step shape. Optionally, after filling the irregular edge and performing exposure curing, the upper surface of the filler 430 is substantially flush with the upper surface of the wafer. The difference between the upper surface of the filler 430 and the upper surface of the wafer can be on the micrometer scale to meet the process requirements. As shown in fig. 4B, after the filling and curing process is completed, the filling surface of the wafer 400, i.e., the surface having the active layer 410, may be attached to the carrier 440 for the subsequent thinning process. The carrier 440 may effectively protect the wafer 400 during the thinning process. Due to the fact that the irregular edge of the wafer is remolded, the splitting rate in thinning processing is reduced, and the difficulty of the thinning process and the production cost are reduced.

Fig. 5 is a flow diagram of a wafer process 500 according to an example embodiment of the present application. As shown in fig. 5, the method comprises the steps of: s1, filling the irregular edge part of the wafer with fillers; s2, curing the filler; s3, after the curing process, the wafer is thinned.

Specifically, the wafer to be thinned may include an active layer in which, but not limited to, a memory array and/or peripheral circuitry may be formed, and a base layer, which may be, but not limited to, a semiconductor material such as monocrystalline silicon. The side of the wafer near the active layer may have, but is not limited to, an irregular edge in the shape of a step. In filling the irregular edge portion of the wafer with the filler (S1), the sub-frame may be used. The sub-frame may be disposed around the wafer, and a groove for receiving the filler may be formed between the sub-frame and a surface of the irregular edge portion of the wafer. The filler may be, but is not limited to, a resin. Alternatively, to increase the filling capacity of the filling, the filling may be dissolved in a specific liquid. Optionally, the filling may also have a certain viscosity. The filler may fill irregular edges of the wafer surface while surrounding the bumps on the wafer surface. In the filling process, factors such as speed and time for adding the filler can be controlled, so that the upper surface of the filler is flush with the upper surface of the wafer to be thinned. Optionally, the height difference between the upper surface of the filler and the upper surface of the wafer may also be selected according to the volume change of the filler after the subsequent curing process.

In the curing process (S2), an exposure curing process, a heating curing process and/or a normal temperature curing process may be used to increase the strength of the filler and the adhesion strength to the wafer surface. For example, the filler may be irradiated with ultraviolet light of an appropriate wavelength to perform an exposure curing process; when the filler is a resin material, the filler may be baked at a temperature of 120 to 400 ℃ for 1 to 10 minutes to perform a heat curing process; the filler may be air-dried using an air blower to perform an ambient curing process. The choice of curing method depends on the requirements of the filling material and the wafer, and the curing time depends on the curing method and the filling material. After the curing process, the upper surface of the filler may be flush with the upper surface of the wafer to be thinned. Optionally, the height difference between the upper surface of the filler and the upper surface of the wafer may be in the order of micrometers to meet the requirements of the subsequent processes.

When the wafer is subjected to the thinning process (S3) after the curing process, a grinding process, a chemical mechanical polishing process, and/or an etching process may be used. In one embodiment, the unfilled back of the wafer may be thinned first by a grinding process that improves process efficiency and reduces the total time for thinning, the thickness of the wafer is thinned to 30 to 400 μ 0, and then the thinned thickness is finely controlled by chemical mechanical polishing. In another embodiment, the thickness of the wafer may be first reduced to a predetermined thickness by a grinding process, for example, the thickness of the wafer may be reduced to 5 to 10 μm greater than the predetermined thickness, and then the thickness of the wafer may be reduced to the predetermined thickness by a wet etching process. In the thinning process, the filler can not only protect the exposed device structure at the edge of the wafer from being damaged, but also reduce or avoid the pollution to the wafer caused by the stripping object formed in the thinning process. After the thinning process, the filler may be removed by using a cleaning process and/or a heat treatment process.

By using the wafer processing device and the processing method of the embodiment, the problem of high splintering rate in the thinning process of the irregular edge wafer in the prior art can be solved, the qualification rate of products can be greatly improved, and the process difficulty and the production cost can be reduced.

Although in the exemplary embodiments of the present application, a wafer having a step-shaped edge is described as an example, it should be understood that the concepts of the present application may be applied to any other wafer structure having an irregular edge.

The above description is only an embodiment of the present application and an illustration of the technical principles applied. It will be appreciated by a person skilled in the art that the scope of protection covered by the present application is not limited to the embodiments with a specific combination of the features described above, but also covers other embodiments with any combination of the features described above or their equivalents without departing from the technical idea. For example, the above features may be replaced with (but not limited to) features having similar functions disclosed in the present application.

Claims

1. A wafer processing apparatus, comprising:

a wafer placing section configured to place the wafer, wherein the wafer has an irregular edge portion;

an auxiliary frame configured to surround the wafer and to come into abutting contact with a surface of the irregular edge portion of the wafer to form a groove;

a filler addition part configured to add a filler in the groove; and

and the thinning device is configured to perform thinning treatment on the wafer added with the filler.

2. The apparatus of claim 1, wherein the filler addition portion is configured to make an upper surface of the filler flush with an upper surface of the wafer.

3. The apparatus of claim 1, further comprising a curing unit configured to cure the filler within the recess.

4. The apparatus of claim 1, wherein the sub-frame has an annular shape to surround the wafer.

5. The apparatus of claim 1, wherein the sub-frame is adjustable in shape and size to be in conforming contact with a surface of the irregular edge portion of the wafer to form the recess.

6. The apparatus of claim 1, wherein the filler comprises a resin.

7. The apparatus according to claim 3, wherein the curing unit is configured to at least one of: exposure curing treatment, heating curing treatment and normal temperature curing treatment.

8. The apparatus of claim 1, further comprising a filler removal unit configured to remove the filler after the thinning process.

9. The apparatus according to claim 8, wherein the filler removing unit is configured to remove the filler through a cleaning process and/or a heat treatment process.

10. The apparatus of claim 3, further comprising a transfer unit configured to transfer the wafer between at least two of the wafer placement section, the curing unit, and the thinning apparatus.

11. A method of processing a wafer, wherein the wafer has irregular edge portions, the method comprising:

arranging an auxiliary frame around the wafer to be in fit contact with the surface of the irregular edge part of the wafer and form a groove;

adding filler into the groove;

curing the filler; and

and after the solidification treatment, thinning the wafer.

12. The method of claim 11, wherein adding filler in the recess to fill the irregular edge portion of the wafer comprises: forming the filler to have an upper surface flush with an upper surface of the wafer.

13. The method of claim 11, wherein the filler comprises a resin.

14. The method according to claim 11 or 13, wherein the curing process comprises an exposure curing process, a heating curing process and/or an ambient curing process.

15. The method of claim 11 or 12, further comprising removing the filler after the thinning step.

16. The method of claim 15, wherein the step of removing the filler comprises removing the filler using a cleaning process and/or a heat treatment process.

17. The method of claim 11, wherein the wafer comprises an active layer and a base layer, the active layer having memory arrays and/or peripheral circuits formed therein.

18. The method of claim 11, wherein the irregular edge portion has a stepped shape.