JP2010098457A - Method of manufacturing element for crystal vibrator, and element for crystal vibrator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing an element for a crystal vibrator that prevents foreign matter from sticking on a formation area for a group of elements for crystal vibrators and the area from damaging in a process of forming the elements for the crystal vibrators. <P>SOLUTION: The method of manufacturing elements for crystal vibrators includes: a process of using a wafer W having the element group formation area 50 made thinner than other areas by entirely forming hollow portions 21 and 41, forming laminate masks in the element group formation area 50 at borders between section areas 50a of elements for crystal vibrators, and adjusting the thickness of the wafer W in each element group formation area 50 to a size corresponding to a frequency; and a process of forming a mask for external shape formation of a crystal piece in each element group formation area 50 and forming an external shape of the crystal piece along the mask for external shape formation. The hollow portions 21 and 41 are provided in the element group formation area 50 to prevent the element formation area 50 from coming into contact with a stage, etc., and to prevent sticking of foreign matter on and damage to an element for a crystal vibrator formed of a section area 50a. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a technology for manufacturing a crystal resonator element and a crystal resonator element manufactured by the technology.

  Conventionally, a large number of crystal pieces are formed from AT-cut crystal wafers, and excitation electrodes and lead electrodes are formed on the crystal pieces to manufacture a large number of crystal resonator elements. The frequency characteristic of the crystal unit is determined by the thickness of the crystal piece of the crystal unit. In recent years, the required frequency characteristics are from 10 MHz to several hundred MHz, and in order to achieve the characteristics, the thickness of the crystal piece needs to be several μm to several tens μm. When forming this crystal piece, if the thickness of the crystal wafer is adjusted to the thickness of the crystal piece, the workability and productivity will be reduced because it is too thin, so when forming the crystal piece, as shown in FIG. A crystal piece is formed using a wafer W1 having a thickness that is easy to work, for example, 300 μm.

  When a crystal piece is formed from a crystal substrate such as the wafer W1, the recess 103 is formed by etching, and the thickness between the bottom 103a and the back surface 104 of the recess 103 is set to a thickness of the crystal piece determined in advance according to the frequency. Then, a crystal piece is formed on the bottom 103a. Therefore, in the wafer W1, after forming the recess 103, it is necessary to check whether the thickness between the bottom 103a and the back surface 104 has a desired frequency characteristic. Therefore, frequency measurement is performed by the probe 110 on the crystal between the bottom 103a and the back surface 104. This frequency measurement is performed by placing the wafer W1 on the stage 111 (see FIG. 9) and bringing the probe 110 into contact with the bottom of the recess 103.

  At this time, the entire back surface 104 of the wafer W1 is in contact with the stage 111. Since the crystal piece formed from the wafer W1 is formed so that the back surface 104 becomes one surface thereof, when there is a foreign substance or the like on the stage 111, the foreign substance adheres to the back surface 104, and as a result, the crystal piece to which the foreign substance adheres is formed. There is a risk of formation. Further, when a fine protrusion is formed on the stage 111, when the wafer W1 is placed, the back surface 104 and the protrusion come into contact with each other, and a contact mark is formed on the back surface 104. As a result, a crystal piece with a contact mark is formed. There is a risk of formation. Further, there is a possibility that the back surface 104 will be hit against the corner of the stage 111 to cause damage, and there is a risk that a damaged crystal piece will be formed. The same problem occurs even when a resist is applied to the front surface 102 of the wafer W1 for exposure, and then the resist is applied to the back surface 104 of the wafer W1 for exposure. Since such a crystal piece cannot obtain a desired frequency characteristic, these crystal pieces are defective, which causes a reduction in production efficiency of the crystal resonator element. Accordingly, there is a need for a method for forming an element for a crystal resonator that can prevent foreign matter from adhering to a forming region for forming a crystal piece and contact with other members.

  On the other hand, Patent Document 1 discloses a semiconductor wafer in which the central portion is thinned in advance and the peripheral portion is simply dropped to omit the backside polishing process of the semiconductor wafer, and the central portion is protected at the peripheral portion and the central portion is difficult to break. Are listed. However, what is described in Patent Document 1 is a semiconductor wafer, and does not form a single crystal piece by etching by forming a laminated mask on both sides like a quartz wafer W1. Then, as described in Patent Document 1, if the central portion is simply thinned, a gap is generated during the photolithography process due to the difference in thickness between the thinned portion and the thick outer peripheral portion, and a desired resist mask can be obtained. There is no possibility. Further, since the wafer is a semiconductor wafer, there is a problem that the wafer is easily broken by thinning the wafer. In order to solve this problem, the thickness of the peripheral portion is increased. However, quartz wafers are difficult to break, and such a problem does not exist.

Japanese Utility Model Publication No. 61-186230 (lower part of page 2)

  The present invention has been made in view of such circumstances, and an object of the present invention is to prevent foreign matter from adhering to the formation region of the crystal resonator element group or scratching the region in the crystal resonator element formation step. An object of the present invention is to provide a method for manufacturing an element for a crystal resonator that can prevent the occurrence of sag.

In the method for manufacturing a crystal resonator element of the present invention,
In the manufacturing method of the element for a crystal resonator that forms an electrode when forming the outer shape of a plurality of crystal pieces on a crystal substrate, and then separates the crystal pieces,
Using a quartz substrate that has been made thinner than the other regions by denting the entire formation region of the crystal resonator element group on both sides,
A mask is formed at the boundary between the formation regions of the crystal resonator elements in the formation region of the crystal resonator element group, and the thickness of the crystal substrate in each formation region corresponds to the frequency by etching. Adjusting the dimensions to be
Forming a crystal piece outline forming mask in each of the formation regions, and removing the crystal in the formation region by etching along the outline formation mask to form an outline of the crystal piece. It is a feature.

  The formation region of the crystal resonator element group is a region where a plurality of crystal resonator element formation regions are arranged vertically and horizontally. Further, the depth of the formation region of the crystal resonator element group before the step of adjusting the thickness of the crystal substrate in each of the formation regions is 0.5 to 5 μm. The crystal resonator element of the present invention is manufactured by the above-described method for manufacturing a crystal resonator element.

  According to the present invention, in the previous step of forming a crystal piece for a crystal resonator element from a crystal substrate, the entire formation region of the crystal resonator element group on both sides of the crystal substrate is recessed to make it more than other regions. The thickness is reduced, a mask is formed in this formation region, the thickness of the quartz substrate is adjusted, and a quartz piece is formed. For this reason, since other members do not come into contact with the formation region of the crystal resonator element group, it is possible to prevent adhesion of foreign matters to the formation region, formation of contact marks, and damage to the formation region. Since the crystal piece formed in the formation region is not affected by foreign matter, damage to the formation region, etc., the crystal resonator element formed based on this crystal piece can suppress the deterioration of characteristics and can achieve a desired frequency. A crystal resonator element having characteristics can be provided.

  A method for manufacturing a crystal resonator element according to this embodiment will be described with reference to FIGS. In the present embodiment, as shown in FIG. 1A, a plurality of partition regions 50a, which are formation regions for forming one element on a wafer W that is a quartz substrate, are arranged in a matrix form, for example, 30 × 30. is doing. If the entire group of the partition regions 50a is referred to as an element group formation region 50, in the present embodiment, the depth d1 is set to 0. 0 in the portion corresponding to the element group formation region 50 on the front surface 20 and the back surface 40 of the wafer W. 5 μm to 5 μm indentations 21 and 41 are formed so as to be thinner than other regions, and partition regions 50 a are arranged therein. In this embodiment, as shown in FIG. 1B, a quartz substrate having a thickness d of 30 μm to 300 μm and a diameter R of 3 to 8 inches is used as the wafer W, and the recesses 21 and 41 are formed by etching. It is formed. For convenience of explanation, in FIG. 1A, the boundary line of the partition region 50a that cannot be actually seen is shown by a solid line. In addition, although the partitioned areas 50a are arranged in a 30 × 30 matrix, only one partitioned area 50a is shown in FIG. 1, and description of the other partitioned areas is omitted. Moreover, the description about the inclined part formed in the peripheral part of the hollow parts 21 and 41 is abbreviate | omitted.

  The process of forming the hollow parts 21 and 41 is performed as follows. As shown in FIG. 2A, a metal film 2 and a resist film 3 made of Cr (chromium) and Au (gold) are formed on the front surface 20 and the back surface 40 of the wafer W, respectively, and shown in FIG. Thus, a resist mask is formed by photolithography and the metal film 2 is etched by a KI (potassium iodide) solution to form a laminated mask 4. Then, as shown in FIG. 2C, the wafer W is immersed in a hydrofluoric acid solution, and etching is performed on the wafer W, so that the entire surface of the element group forming region 50 on the front surface 20 and the back surface 40 of the wafer W is recessed. The part 21 and the hollow part 41 are formed, and the metal film 2 and the resist film 3 are peeled off as shown in FIG. In the present embodiment, when a process such as a film forming process for forming the metal film 2 or the resist film 3 on the back surface 40 is performed, the process is performed by inverting the wafer W. FIGS. 1B and 2A to 2B schematically show a cross section taken along the line AA corresponding to the diameter of the wafer W shown in FIG. .

  Using the wafer W obtained in this way, a crystal resonator element is formed as follows. First, as shown in FIG. 3A, the metal film 5 and the resist film 6 are formed on the recesses 21 and 41 and the front surface 20 and the back surface 40 of the wafer W, respectively. Then, as shown in FIG. 3B, a resist mask is formed on the resist film 6 in the depression 21 by photolithography, and the metal film 5 is etched with a KI (potassium iodide) solution to form a laminated mask 7. To do. In the present embodiment, the resist mask is formed by reduction projection exposure, and the initial setting of the exposure apparatus can obtain a desired resist mask for the resist film 6 formed on the surface 20. Is set to Moreover, FIG. 3 has shown the cross section of the arrow AA of FIG. 1 (a) similarly to FIG.

  After the exposure, development is performed to form a resist mask. When etching is performed along the resist mask, the metal film 5 and the resist film 6 remain in the boundary portion 13b between the partition regions 50a on the surface 20 side. A layered mask 7 for adjusting the thickness is formed by the metal film 5 and the resist film 6 remaining in the portion 13b. Next, as shown in FIG. 3C, the wafer W is immersed in a hydrofluoric acid solution and etching is performed to form the recess 13 for adjusting the thickness of the wafer W for each partition region 50a. Then, as shown in FIG. 3D, the metal film 5 and the resist film 6 are peeled off. When the recess 13 is formed, the crystal corresponding to the region of the bottom 13a of the recess 13, that is, the thickness of the crystal between the bottom 13a of the recess 13 and the bottom surface of the recess 41 on the back surface 40 side, has a desired frequency characteristic. Measure and confirm whether you have This measurement is performed using a probe apparatus 10 for measuring a frequency as shown in FIG. First, as shown in FIG. 4A, the wafer W is transported and placed on the stage 11. Next, as shown in FIG. 4B, the measurement terminal 10a of the probe apparatus 10 is brought into contact with the bottom 13a from above the wafer W, and the frequency of the bottom 13a is measured. When the thickness between the bottom portion 13a and the recess portion 41 does not reach a desired thickness, the bottom portion 13a is partially etched to finely adjust the thickness between the bottom portion 13a and the recess portion 41.

  The thickness of the crystal corresponding to the region of the bottom portion 13a (the thickness of the crystal between the bottom portion 13a of the recess 13 and the bottom surface of the recess portion 41 on the back surface 40 side) is such that a desired frequency characteristic can be obtained. When fine adjustment is performed, an element is formed using the crystal in the region of the bottom portion 13a. First, as shown in FIG. 5A, the metal film 8 and the resist film 9 are formed on the recess 13, the recesses 21 and 41, and the front surface 20 and the back surface 40 of the wafer W. Then, the metal film 8 and the resist film 9 are etched by the above-described photolithography and KI solution to form an outer shape mask pattern 68 for forming the outer shape of the crystal piece 1 as shown in FIG. To do. Next, the wafer W is etched along the outer shape mask pattern 68 to form the crystal piece 1 as the base of the element from the wafer W as shown in FIG. 5C, and the remaining metal film 8 and resist film 9 is peeled off. At this time, the crystal piece 1 is connected and supported on the wafer W by the thin bridge-shaped connection support portion 15.

  When the crystal piece 1 is formed, a metal film 16 and a resist film 17 are formed on the entire surface of the crystal piece 1 as shown in FIG. 6A, and photolithography and KI solution are shown in FIG. 6B. A mask pattern is formed by the etching. Then, as shown in FIG. 6C, the metal film 16 is etched to form excitation electrodes 51 and 52 and extraction electrodes 53 and 54, the resist film 17 is removed, and as shown in FIG. 6D. For example, by cutting the connection support portion 15 by laser dicing, individual crystal resonator elements as shown in FIG. 7 are formed. 5 and 6 show only a part of the wafer W on the + X side of the wafer W shown in FIG.

  As shown in FIGS. 7A and 7B, this crystal resonator element has an excitation electrode 51 formed on the element surface 22 of the crystal piece 1 and an excitation electrode 52 formed on the element back surface 42. Are connected to the extraction electrode 53, and the excitation electrode 52 is connected to the extraction electrode 54. The lead electrodes 53 and 54 extend from the element surface 22 and the element back surface 42 on which the connected excitation electrodes 51 and 52 are formed, to the side surface 15a on which the connection support portion 15 is formed, and through the side surface 15a. It extends to the element surface 22 and the element back surface 42 facing each other. Therefore, the extraction electrodes 53 and 34 are formed to be aligned on the side surface 15a.

  According to the above-described embodiment, after the depressions 21 and 41 are formed in the element group formation region 50 and the whole is thinned from both sides, the element group formation region 50 is laminated for each partition region 50a by photolithography etching. A mask 7 is formed, and the thickness of each section is adjusted, the outer shape of the crystal piece 1 is formed, and each electrode is formed. For this reason, the stage 11 or the like is used at the time of exposure by a photolithography process for forming the laminated mask 7 for each partition region 50a, or at the time of measuring the frequency using the probe 10 for fine adjustment of the thickness between the bottom 13a and the back surface 40. The element group forming region 50 facing the stage 11 is in a state of being lifted from the stage 11 and is not in contact with the stage 11. Accordingly, the adhesion and damage of foreign matter to the element group formation region 50 can be prevented, and the adhesion and damage of foreign matter to the crystal resonator element formed by the partition region 50a arranged in the element group formation region 50 can be prevented. be able to.

  Further, when the crystal piece 1 is formed from the wafer W, and the excitation electrodes 51 and 52 and the extraction electrodes 53 and 54 are formed, the crystal vibration is caused by the depressions 21 and 41 formed on the entire surface of the element group formation region 50. Since all the surfaces of the child element do not come into contact with other members until the element is separated, adhesion of foreign matters to the crystal piece 1, damage, and the like are suppressed even in the process of forming the crystal oscillator element. Then, it is possible to prevent deterioration of characteristics of the formed crystal resonator and to form a crystal resonator element having desired frequency characteristics. On the other hand, when the thickness is adjusted by etching only the partition area from one side of the wafer W, there arises a problem that foreign matters adhere to the surface on the side where the mounting table is placed and are easily damaged. Therefore, it is better to thin the entire group of partition regions 50a, that is, the entire element group formation region 50 in advance.

  In the present embodiment, in order to make the element group formation region 50 thin, the depressions 21 and 41 having a depth of 0.5 μm to 5 μm are formed. On the other hand, as described above, in this embodiment, a resist mask is formed by reduced projection exposure, and the initial setting of the exposure machine is to obtain a desired resist mask for the resist film 6 formed on the surface 20. Is set to be possible. For this reason, the imaging position of the light applied to the resist film 6 in the depressions 21 and 41 during exposure changes by the depth of the depressions 21 and 41. Accordingly, a gap corresponding to the depth of the recesses 21 and 41 is generated between the desired resist mask shape and the actually formed resist mask shape. However, since the depths of the recesses 21 and 41 are set to 0.5 μm to 5 μm, the gap of the resist mask shape can be kept within an allowable range even if a gap occurs in the width of light during photolithography. Thus, even when using an exposure machine that does not have the function of correcting and resetting the focal depth, exposure can be performed with high accuracy and a desired resist mask can be obtained.

  The depressions 21 and 41 are formed for the purpose of preventing foreign matter from adhering to the element group forming region 50 and damaging the element group forming region 50, and the depth of 5 μm is sufficient. It is known to be effective. That is, even if the depths of the recesses 21 and 41 are 5 μm or more, there is an effect in preventing the adhesion and damage of foreign matters. However, if this depth is increased, the working time increases in the step of forming the recesses 21 and 41, and therefore it is not preferable to increase the recesses 21 and 41. Therefore, in the present embodiment, the depth of the depressions 21 and 41 is set to about 0.5 μm to 5 μm, thereby suppressing an increase in working time in the process of forming the depressions 21 and 41.

  In the embodiment of the present invention, the element formation region may not be one region over the entire wafer W like the element group formation region 50 of the embodiment. For example, the element formation region of the embodiment is divided into four parts, each of the element formation regions is provided with a recess, and individual element formation regions are not connected to each other, and a crystal resonator element is formed in each element formation region. Also good. In the present embodiment, the method for manufacturing a rectangular crystal resonator element has been described. However, the embodiment of the present invention can also be applied to a manufacturing method for manufacturing a tuning fork type crystal resonator element. .

  Next, a crystal resonator 70 using the crystal resonator element of the present embodiment will be described with reference to FIG. As shown in FIGS. 8A and 8B, the crystal resonator 70 conducts the lead electrodes 32 and 33 of the crystal resonator element to a pair of electrodes 72 provided in an exterior body (container) 71. It mounts by adhering in the aspect electrically connected by the adhesive agent 73. FIG. And the external electrode 74 and the electrode 72 provided in the lower part of the exterior body 71 are electrically connected via the wiring in the exterior body 71, By connecting this external electrode 74 with the electrode of an electronic device, The crystal resonator element is electrically connected to the electronic component. Therefore, it is possible to provide an electronic component on which the crystal resonator element of this embodiment is mounted. Examples of such electronic components include communication devices and measuring devices.

It is the 1st explanatory view for explaining wafer W for obtaining the element for crystal oscillators of this embodiment. It is a 1st explanatory view for explaining the manufacturing process of the element for crystal oscillators of this embodiment. It is the 2nd explanatory view for explaining the manufacturing process of the element for crystal oscillators of this embodiment. It is explanatory drawing for demonstrating the frequency measurement of the wafer W of this embodiment. It is a 3rd explanatory view for explaining the manufacturing process of the element for crystal oscillators of this embodiment. It is the 4th explanatory view for explaining the manufacturing process of the element for crystal oscillators of this embodiment. It is a perspective view of the element for crystal oscillators of this embodiment. It is a top view of the crystal oscillator of this embodiment. It is explanatory drawing for demonstrating the frequency measurement of the conventional wafer W1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Crystal piece 2, 5, 8, 16 Metal film 3, 6, 9, 17 Resist film 4, 7 Laminated mask 10, 110 Probe 11, 111 Stage 13, 103 Recessed part 13a Bottom part 13b Boundary part 15 Connection support part 20 Surface 21 41 Indentation part 22 Element surface 40 Back surface 42 Element back surface 50 Element group formation area (entire formation area)
50a Partition area (formation area)
51, 52 Excitation electrode 53, 54 Extraction electrode 68 External mask pattern 70 Crystal resonator W, W1 Wafer

Claims (4)

In the manufacturing method of the element for a crystal resonator that forms an electrode when forming the outer shape of a plurality of crystal pieces on a crystal substrate, and then separates the crystal pieces,
Using a quartz substrate that has been made thinner than the other regions by denting the entire formation region of the crystal resonator element group on both sides,
A mask is formed at the boundary between the formation regions of the crystal resonator elements in the formation region of the crystal resonator element group, and the thickness of the crystal substrate in each formation region corresponds to the frequency by etching. Adjusting the dimensions to be
Then, forming a mask for forming the outer shape of the crystal piece in each of the forming regions, and removing the crystal in the forming region by etching along the mask for forming the outer shape to form the outer shape of the crystal piece. A method for manufacturing an element for a crystal resonator.   2. The method for manufacturing a crystal resonator element according to claim 1, wherein the formation region of the crystal resonator element group is a region in which a plurality of crystal resonator element formation regions are arranged vertically and horizontally. .   2. The crystal resonator element group formation region before the step of adjusting the thickness of the crystal substrate in each of the formation regions has a depth of 0.5 to 5 μm. 3. A method for producing a crystal resonator element according to 2.   A crystal resonator element manufactured by the method for manufacturing a crystal resonator element according to claim 1.

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