JP2013086208A - Wafer processing method, method of manufacturing electronic component, and electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wafer processing method, a method of manufacturing an electronic component, and an electronic component, capable of preventing damage such as cracking or chipping of a wafer being processed.SOLUTION: The wafer processing method includes a thick part formation step for forming a frame-like thick part 12 on a main surface of a wafer, and a polishing step for polishing a thin part 14 which is a region surrounded with the thick part 12.

Description

  The present invention relates to a wafer processing method, an electronic component manufacturing method, and an electronic component that perform polishing while preventing breakage.

  Conventionally, electronic components such as piezoelectric vibrators and semiconductors are manufactured from large wafers. The wafer is polished to a desired thickness, and then processed into an electronic component. In order to prevent breakage such as cracking or chipping of the wafer during wafer polishing, chamfering of the outer periphery of the wafer is performed before wafer polishing (see, for example, Patent Document 1). In Patent Literature 1, the wafer is chamfered while rotating the wafer on the table, pressing the wafer against the groove of the rotating grindstone, and supplying grinding water to the bottom of the grinding groove where the wafer and the grindstone contact each other. Is going.

JP 2000-218521 A

In the grinding method as described in Patent Document 1, since a local force is applied to the wafer during grinding, it is difficult to chamfer when the wafer is a thin plate.
In addition, the grinding method has to be a so-called single wafer processing method in which wafers are processed one by one, so that the efficiency is low and the cost is high.

The present invention has been made to solve the above problems, and provides a wafer processing method, an electronic component manufacturing method, and an electronic component that can prevent breakage, chipping, and the like of the wafer being processed. With the goal.
It is another object of the present invention to provide an electronic component manufacturing method and an electronic component that can be efficiently processed.

SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.
Application Example 1 includes a thick part forming step of forming a frame-like thick part on the main surface of the wafer, and a polishing step of polishing the thin part of the main surface surrounded by the thick part. A wafer processing method characterized by the above.
According to the present invention, after forming the frame-shaped thick part on the main surface of the wafer, the region surrounded by the thick part is polished, so that the wafer can be prevented from being damaged during the wafer processing. it can.

Application Example 2 The wafer processing method according to Application Example 1, wherein polishing is performed using a suede-type pad in the polishing step.
According to the present invention, since copying can be performed by polishing using a suede-type pad, even if the thick portion is provided, the region surrounded by the thick portion can be polished uniformly. Can do.

Application Example 3 The wafer processing method according to Application Example 1 or 2, wherein, in the thick part forming step, the thick part is formed by etching.
According to the present invention, since the thick part can be formed by etching, the thick part can be formed at a time on a plurality of wafers, and the wafer can be processed efficiently.

[Application Example 4] The wafer processing method according to any one of Application Examples 1 to 3, wherein, in the thick part forming step, the thick part is provided at a peripheral part of the wafer.
According to the present invention, by providing the thick portion at the peripheral portion of the wafer, the wafer can be reinforced, and the wafer can be prevented from being damaged during processing.

Application Example 5 In the thick part forming step, the thick part integrated with the thick part provided at the peripheral part is also provided inside the main surface of the wafer. The wafer processing method described in Example 4.
According to the present invention, the wafer can be further reinforced as compared with the case where the thick portion is provided only at the peripheral portion of the wafer, and the wafer can be prevented from being damaged during the wafer processing.

Application Example 6 The wafer processing method according to any one of Application Examples 1 to 5, wherein in the polishing step, polishing is performed so that at least a part of the thick portion remains.
According to the present invention, when an electronic component or the like is manufactured using a wafer after the polishing process is completed, the wafer can be prevented from being damaged in the manufacturing process, and the handling of the wafer is facilitated.

Application Example 7 An outer shape forming step of forming an outer shape of an element of an electronic component in a thin portion surrounded by the thick portion of the wafer processed by the processing method described in Application Example 1, A method of manufacturing an electronic component, comprising: a separation step of separating from a thick portion; and a mounting step of mounting the element in a package.
According to the present invention, by leaving a thick portion on a polished wafer, even when an electronic component is manufactured from the polished wafer, the wafer can be prevented from being damaged, and the wafer can be handled easily. It becomes.

  Application Example 8 An electronic component manufactured by the manufacturing method according to Application Example 7.

It is a flowchart which shows the procedure of the wafer processing method which concerns on embodiment of this invention. It is a top view of the wafer manufactured by passing through the process to step S1-S7. It is AA sectional drawing of the wafer shown in FIG. It is a top view of a wafer at the time of providing a thick part besides an outer peripheral part and an outer peripheral part concerning a modification. It is BB sectional drawing of the wafer shown in FIG. It is a figure which shows the experimental result whether the whole surface of the thin part was finished in a mirror surface, or the part which does not become a mirror surface remained when a wafer was grind | polished with the polishing pad which has each pad hardness and NAP length. It is a top view of a wafer at the time of forming a thick part in one principal surface concerning a modification. It is CC sectional drawing of the wafer shown in FIG. It is a flowchart which shows the procedure of the piezoelectric vibrator manufacturing method using the wafer which grinding processing was completed leaving all or a part of thick part. It is a figure of the wafer by which the external shape of the coupling body of the piezoelectric vibrator was formed in the thin part. It is a figure which shows an example of the electronic device by which a piezoelectric vibrator is mounted.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
First, a wafer processing method according to an embodiment of the present invention will be described.
FIG. 1 is a flowchart showing a procedure of a wafer processing method according to an embodiment of the present invention. This wafer processing method is a method for manufacturing a polished wafer by polishing a crystal wafer.

First, an artificial quartz is prepared, and a lambard process, which is a grinding process performed to clarify the crystal axis of the quartz, is performed on the artificial quartz (step S1).
Next, the artificial quartz after the lumbar processing is sliced into a wafer having a thickness of about 150 μm at a necessary angle with respect to the crystal axis to generate a plurality of wafers (step S2).

Next, the outer shape of the wafer is processed (step S3). In this embodiment, it is processed into a disk shape having a diameter of about 3 inches. In addition, it is not limited to disk shape, For example, you may process into a plate shape whose planar shape is a rectangle.
Next, the wafer is lapped to a thickness of about 100 μm (step S4).

Next, using photolithography technology, thin portions are formed on the wafer, and thick portions thicker than the thin portions are formed on the peripheral portions of both main surfaces of the wafer (thick portion forming step). ).
Specifically, first, a photoresist is applied to both main surfaces of the wafer. Then, both main surfaces are covered with a photomask for forming a thin portion, and the photoresist in the inner portion excluding the peripheral portion of the wafer is exposed. Next, development is performed, and the exposed portion is removed, thereby forming a thin outline pattern on the photoresist (step S5).

Next, the wafer is immersed in an etching solution, and the inner portion of the wafer not covered with the photoresist is etched by about 10 μm per side to form a thin portion having a thickness of about 80 μm (step S6). In this case, by soaking a plurality of wafers in an etching solution, so-called batch processing can be performed in which thin portions are collectively formed on the plurality of wafers. Thereby, productivity can be improved and cost reduction can be achieved.
Next, the photoresist is removed from the wafer (step S7).

FIG. 2 is a plan view of the wafer 1 manufactured through the steps S1 to S7, and FIG. 3 is a cross-sectional view taken along the line AA of the wafer 1 shown in FIG.
As shown in these drawings, the wafer 1 has a frame-shaped thick portion 12 formed at the peripheral portions of both main surfaces. In addition, a thin portion 14 that is thinner than the thick portion 12 is formed in a region surrounded by the thick portion 12. Thereby, the vertical cross-sectional shape of the wafer 1 is H-shaped as shown in FIG.

  Thus, by forming the thick portion 12 on the wafer 1, the mechanical strength of the wafer 1 can be improved and the thin portion 14 can be prevented from being damaged. Therefore, handling in subsequent steps is facilitated.

  Next, double-side polishing processing (double-side polishing processing) is performed on the region of the thin portion 14 surrounded by the thick portion 12 using a polishing pad (step S8, polishing step). This polishing is performed until the thickness of the thin portion 14 becomes about 60 μm.

  FIG. 6 shows that when the wafer 1 is polished with a polishing pad having each pad hardness and NAP length (pad thickness) shown in the same figure, the entire surface of the thin portion 14 is finished to a mirror surface or does not become a mirror surface. It is a figure which shows the experimental result of whether the part remained.

  As shown in the figure, when the pad hardness of the polishing pad is 30 to 80 and the NAP length is 0.2 to 1.0 mm, the entire surface of the thin portion 14 can be finished to a mirror surface. This is because the polishing pad can perform so-called copying that follows the uneven shape of the wafer 1. Therefore, the pad hardness and NAP length of the pad used for polishing the wafer 1 are preferably within the above ranges. For example, when the material is a suede type, the pad hardness and the NAP length are within the above ranges, and therefore, it is preferable to polish using a suede type polishing pad.

  By using such a soft polishing pad that can be copied, the entire surface of the thin portion 14 of the wafer 1 can be mirror-finished, and even if the thin portion 14 is thin and the diameter of the wafer 1 is large, The thin portion 14 can be prevented from being damaged, and a polished wafer can be produced with a high yield.

  Further, polishing may be performed so that the thickness of the thick portion 12 is the same as the thickness of the thin portion 14, but by polishing so that all or part of the thick portion 12 remains, this polishing wafer can be polished. Even when an electronic component such as a piezoelectric vibrator is manufactured, the thin portion 14 can be prevented from being damaged, so that subsequent wafer handling becomes easy.

  In addition, although it demonstrated as performing double-sided polish process in step S8 of embodiment mentioned above, it is not limited to this, You may perform a lapping process. That is, the process of step S8 can be grasped by a wide concept of “polishing” process including polishing and lapping. Further, not only double-side polishing but single-side polishing may be performed.

  Further, the thick portion may be provided in addition to the peripheral portion in addition to the peripheral portion of the wafer. FIG. 4 is a plan view of the wafer 1A when the thick portion is provided at a portion other than the peripheral portion, and FIG. 5 is a cross-sectional view taken along the line BB of the wafer 1A shown in FIG. As shown in these drawings, in addition to the thick portion 12 at the peripheral portion, four thick portions 12a from the center toward the outer peripheral end may be provided in a cross shape so as to be perpendicular to each other. As a result, the thick portions 12 and 12a are connected and integrated with each other, and four regions surrounded by the thick portions 12 and 12a are formed on each main surface. Thus, in addition to the thick portion 12 at the peripheral portion, by providing the thick portion 12a also inside the main surface of the wafer 1A, the surface area of the thin portion 14 is smaller than when only the thick portion 12 is provided. However, the mechanical strength can be improved. In addition, the number of the thick parts 12a which go to an outer periphery end from a center is not restricted to four, Arbitrary numbers can be provided.

  Moreover, you may provide a thick part only in one main surface, without providing in both main surfaces. FIG. 7 is a plan view of the wafer 1B when a thick portion is formed only on one main surface, and FIG. 8 is a cross-sectional view of the wafer 1B shown in FIG. In this case, one main surface may be etched using a photoresist covering only the peripheral portion of the wafer as a mask, and the other main surface may be etched using a photoresist covering the entire main surface as a mask.

(Piezoelectric vibrator manufacturing method)
Next, the procedure of the piezoelectric vibrator manufacturing method will be described with reference to the flowchart shown in FIG. In the piezoelectric vibrator manufacturing method, a wafer that has been polished by the wafer processing method described above is used. It is assumed that all or part of the thick portion 12 remains on the wafer.

First, the wafer is cleaned (step S11).
Next, a metal film to be an electrode is formed on both main surfaces of the wafer by sputtering or the like (step S12).

  Next, after applying a photoresist to both main surfaces of the wafer, the photoresist is exposed by covering with a photomask for forming the outer shape of the coupling body of the piezoelectric vibration element. Next, development is performed to remove the exposed portion of the photoresist. Thereby, the external pattern of the coupling body of the piezoelectric vibration element is formed on the photoresist on the thin portion 14 of the wafer (step S13).

  Next, the wafer is immersed in an etching solution and etched until the portion of the wafer that is not covered with the photoresist penetrates in the thickness direction, and as shown in FIG. The outer shape of the coupling body of the element 14a is formed (step S14, outer shape forming step).

Next, the photoresist is removed from the wafer (step S15).
Next, each piezoelectric vibration element 14a formed in the thin part 14 is separated from the thick part 12 by dicing or breaking the connecting part between the piezoelectric vibration elements 14a (step S16, separation step).

  Next, the piezoelectric vibration element 14a is mounted on the package (step S17, mounting process), the frequency of the piezoelectric vibration element 14a is adjusted (step S18), and the inside of the package is hermetically sealed (step S19). Thereby, the piezoelectric vibrator is completed.

As shown in FIG. 11, such a piezoelectric vibrator can be mounted on various electronic devices such as a GPS (Global Positioning System), a mobile phone, a watch, a digital camera, and a game machine. It plays a role as a sensor function such as a reference frequency generation function, a filter function, a pressure sensor, a temperature sensor, and an acceleration sensor.
The method for manufacturing a piezoelectric vibrator described above can also be applied to a method for manufacturing an arbitrary electronic component such as a semiconductor.

In the above-described embodiment, the thin portion 14 of the wafer 1 is formed by wet etching. However, the thin portion 14 may be formed by dry etching without being limited to wet etching. Moreover, you may form the thin part 14 not only by an etching but by grinding with a grindstone.
Moreover, in the said embodiment, although quartz was used as a material of a wafer and a piezoelectric vibration element, it is not limited to quartz, All materials, such as a ceramic, can be used.

1, 1A, 1B... Wafer, 12, 12a, 12b... Thick portion, 14... Thin portion, 14a.

Claims (8)

A thick part forming step for forming a frame-like thick part on the main surface of the wafer;
A polishing step for polishing a thin portion surrounded by the thick portion;
A method for processing a wafer, comprising: In the polishing step,
2. The wafer processing method according to claim 1, wherein polishing is performed using a suede-type pad. In the thick part forming step,
3. The wafer processing method according to claim 1, wherein the thick portion is formed by etching. In the thick part forming step,
4. The wafer processing method according to claim 1, wherein the thick portion is provided at a peripheral portion of the wafer. 5. In the thick part forming step,
5. The wafer processing method according to claim 4, wherein a thick portion integrated with a thick portion provided at the peripheral portion is also provided inside the main surface of the wafer. In the polishing step,
6. The wafer processing method according to claim 1, wherein the polishing is performed so that at least a part of the thick portion remains. An outer shape forming step of forming an outer shape of an element of an electronic component on the thin portion of the wafer processed by the processing method according to claim 1, and a separation step of separating the element from the bank portion;
A mounting step of mounting the element in a package.   An electronic component manufactured by the manufacturing method according to claim 7.

Images