JP2014207638A - Wafer holding jig and anti-corrosion film forming method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress cracking of a crystal wafer resulting from an anti-corrosion film forming process.SOLUTION: A wafer holding jig 10 has: a first holding piece 11 having a first groove 21 whose cross section is V-shaved; and a second holding piece 12 opposite to the first groove 21 and having a second groove 22 whose cross section is V-shaved. A crystal wafer 30 is held between the first groove 21 and the second groove 22. Since an anti-corrosion film can be formed while the first groove 21 and the second groove 22 contact an edge line of the crystal wafer 30, the wafer holding jig 10 does not cover a face of the crystal wafer 30 at the time of forming the anti-corrosion film.

Description

  The present invention relates to a wafer holding jig for holding a quartz wafer when a corrosion resistant film serving as a mask for wet etching is formed on the quartz wafer, and a corrosion resistant film forming method using the wafer holding jig.

  Piezoelectric elements such as tuning-fork type bending vibrators and thickness shear vibrators are, for example, crystal wafer cleaning → corrosion-resistant film formation → element outline pattern formation → electrode pattern formation → crystal wet etching → electrode film formation → lift-off → adjustment film formation → frequency It is manufactured through processes such as adjustment (see, for example, Patent Document 1). Here, in the corrosion resistant film forming step, a corrosion resistant film that serves as a mask in the quartz wet etching step is formed on the quartz wafer. At this time, in order to form a corrosion-resistant film on both sides of the quartz wafer at the same time, a wafer holding jig is used that holds the quartz wafer with both sides of the quartz wafer exposed.

  FIG. 5 is a plan view showing a conventional corrosion-resistant film forming process, and the process proceeds in the order of FIG. 5 [1] to FIG. 5 [3]. Hereinafter, description will be given based on this drawing.

  First, as shown in FIG. 5 [1], a crystal wafer 70 and a wafer holding jig 80 are prepared. The crystal wafer 70 is a rectangular flat plate. The wafer holding jig 80 is a set of two, an outer frame portion 81 having an inner circumference larger than the outer circumference of the crystal wafer 70, and claw portions 82 to 85 protruding inward from the outer frame portion 81; Consists of. As for the wafer holding jig 80, only a portion for holding one crystal wafer 70 is shown.

  Subsequently, as shown in FIG. 5 [2], the quartz wafer 70 is held by the wafer holding jig 80 by sandwiching both surfaces of the quartz wafer 70 by the wafer holding jig 80. At this time, the crystal wafer 70 and the wafer holding jig 80 are brought into close contact with each other using a magnet or the like so that the crystal wafer 70 does not fall off from the wafer holding jig 80. That is, the centers of the four sides of the crystal wafer 70 are sandwiched portions 72 to 75 (FIG. 5 [3]), and these sandwiched portions 72 to 75 are sandwiched from both surfaces by the claw portions 82 to 85 of the wafer holding jig 80. The In this state, corrosion resistant films 71 are formed on both surfaces of the quartz wafer 70 by sputtering or the like.

  Finally, as shown in FIG. 5 [3], the crystal wafer 70 on which the corrosion-resistant film 71 is formed is removed from the wafer holding jig 80. However, since the claw portions 82 to 85 are in surface contact with the sandwiched portions 72 to 75 on the periphery of the crystal wafer 70, the corrosion resistant film 71 is not formed.

  FIG. 6 is a plan view showing a conventional quartz wet etching process, and the process proceeds in the order of FIG. 6 [1] to FIG. 6 [3]. Hereinafter, description will be given based on this drawing.

  First, as shown in FIG. 6 [1], a crystal wafer 70 on which a corrosion-resistant film 71 is formed is prepared. The anticorrosion film 71 is not formed on the sandwiched portions 72 to 75 on the periphery of the crystal wafer 70. Although not shown, the quartz wafer 70 has a portion without the corrosion-resistant film 71 such as an element outer pattern.

  Subsequently, as shown in FIG. 6 [2], wet etching is performed on the quartz wafer 70 on which the corrosion-resistant film 71 is formed using hydrofluoric acid or the like. At this time, a portion of the quartz not covered with the corrosion-resistant film 71 is eroded from the front and back by the etching solution and finally penetrates. Accordingly, the sandwiched portions 72 to 75 on the periphery of the quartz wafer 70 are notched 72 a to 75 a because the corrosion resistant film 71 is not formed.

Japanese Patent No. 4060699

  Various stresses are generated on the crystal wafer 70 during or after the wet etching due to the pressure of the etching solution and the cleaning solution during the manufacturing process, the impact during the transfer, and the like. On the other hand, since the notches 72a to 75a of the crystal wafer 70 are constricted, stress tends to concentrate there. For this reason, as shown in FIG. 6 [3], for example, a crack 76 may occur in a constricted portion between the notch 74a and the notch 75a.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a wafer holding jig and a corrosion-resistant film forming method using the same, which can improve the yield by suppressing cracks in the crystal wafer caused by the corrosion-resistant film forming process.

The wafer holding jig according to the present invention,
In forming a corrosion resistant film as a mask for wet etching on a quartz wafer, in a wafer holding jig for holding the quartz wafer,
A first holding piece having a first groove having a concave cross section, and a second holding piece having a second groove having a concave cross section while facing the first groove,
The crystal wafer is held between the first groove and the second groove.
It is characterized by that.

The method for forming a corrosion-resistant film according to the present invention includes:
A corrosion-resistant film forming method using a wafer holding jig according to the present invention,
By inserting the crystal wafer between the first groove and the second groove, the crystal wafer is held between the first groove and the second groove,
In this state, the corrosion-resistant film is formed on both surfaces of the quartz wafer by sputtering or vapor deposition.
It is characterized by that.

  According to the present invention, the first groove and the second groove are in contact with the ridge line of the crystal wafer by holding the crystal wafer between the first groove having a concave cross section and the second groove having a concave cross section. Since the corrosion resistant film can be formed, the wafer holding jig does not cover the surface of the crystal wafer when forming the corrosion resistant film. Therefore, by reducing the portion where the corrosion-resistant film is not formed during the formation of the corrosion-resistant film, cracks in the crystal wafer due to the corrosion-resistant film forming process can be suppressed, and thus the yield can be improved.

FIGS. 1A and 1B are perspective views illustrating a wafer holding jig according to a first embodiment, in which FIG. 1 [1] is before holding a crystal wafer and FIG. 1 [2] is after holding the crystal wafer. 2 [1] is a cross-sectional view taken along the line II-II in FIG. 1 [2], and FIG. 2 [2] is a cross-sectional view showing an enlarged part of FIG. 2 [1]. FIG. 3 [1] is a schematic view showing a part of the corrosion-resistant film forming method of the first embodiment, and FIG. 3 [2] is a perspective view showing a crystal wafer obtained by the corrosion-resistant film forming method of the first embodiment. . It is a perspective view which shows the wafer holding jig of Embodiment 2. It is a top view which shows the conventional corrosion-resistant film formation process, and a process progresses in order of FIG. 5 [1]-FIG. 5 [3]. It is a top view which shows the conventional quartz wet etching process, and a process progresses in order of FIG. 6 [1]-FIG. 6 [3].

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention (hereinafter referred to as “embodiments”) will be described with reference to the accompanying drawings. In addition, since the shape drawn in drawing is drawn so that those skilled in the art can understand easily, it does not necessarily correspond with an actual dimension and ratio.

  FIG. 1 is a perspective view illustrating a wafer holding jig according to the first embodiment. FIG. 1 [1] is before holding a crystal wafer, and FIG. 1 [2] is after holding a crystal wafer. 2 [1] is a cross-sectional view taken along the line II-II in FIG. 1 [2], and FIG. 2 [2] is a cross-sectional view showing an enlarged part of FIG. 2 [1]. Hereinafter, description will be given based on these drawings. The planes 211, 212, 221, 222, the gaps 231 to 234, and the ridge lines 31 to 34 are shown only in FIG. 2 [2].

  The wafer holding jig 10 according to the first embodiment holds the crystal wafer 30 when forming a corrosion-resistant film serving as a wet etching mask on the crystal wafer 30. The wafer holding jig 10 has a first holding piece 11 having a first groove 21 having a concave section (V-shaped in the first embodiment) and a first section having a concave section (this embodiment). 1 and a second holding piece 12 having a second groove 22, and the crystal wafer 30 is held between the first groove 21 and the second groove 22. In addition, about the wafer holding jig 10, only the part holding the quartz wafer 30 for one piece is illustrated.

  The quartz wafer 30 is, for example, a rectangular Z plate having a main surface, and has a side of 50 mm to 75 mm and a thickness of about 0.1 mm. The cross section of the quartz wafer 30 in the thickness direction is also a quadrangle, and the quadrangle of the cross section includes four ridge lines 31 to 34 (FIG. 2 [2]). An “edge” refers to a boundary line between surfaces in a solid. Therefore, each surface in the solid is an area surrounded by a plurality of ridge lines. Both end points of the ridge line become vertices, and the ridge line is not limited to a straight line but may be a curved line. Since the quartz wafer 30 is a flat rectangular parallelepiped, it has 12 ridge lines.

  The wafer holding jig 10 is made of, for example, stainless steel, and in addition to the first holding piece 11 and the second holding piece 12, the first holding piece 11 and the second holding piece 12 are fixed in a state of standing parallel to each other. A bottom plate 13 is provided. A spacer for providing an appropriate gap may be inserted between the bottom plate 13 and the crystal wafer 30. Since the opposite sides of the first holding piece 11 and the second holding piece 12 to the bottom plate 13 side are opened, the crystal wafer 30 is taken in and out therefrom.

  The 1st holding piece 11 and the 2nd holding piece 12 are elongate rectangular parallelepiped shape, for example, and the 1st groove | channel 21 and the 2nd groove | channel 22 are provided in the mutually opposing surface, respectively. The first groove 21 is, for example, linear in the length direction and has two planes 211 and 212 (FIG. 2 [2]) forming a V shape. Similarly, the second groove 22 has, for example, two planes 221 and 222 (FIG. 2 [2]) that are linear in the length direction and form a V shape. In the first embodiment, the angle formed by the plane 211 and the plane 212 is 90 degrees, and similarly, the angle formed by the plane 221 and the plane 222 is 90 degrees. Therefore, the angle formed between each surface of the first groove 21 and the second groove 22 and each surface of the crystal wafer 30 in contact therewith is 45 degrees. The first groove 21 need not be provided from one end of the first holding piece 11 to the other end, and may be provided only in a part of the first holding piece 11. The same applies to the second groove 22.

  The crystal wafer 30 is held between the first groove 21 and the second groove 22 with gaps 231 to 234 (FIG. 2 [2]). That is, there is a gap 231 between the plane 211 and the ridgeline 31, a gap 232 between the plane 212 and the ridgeline 32, a gap 233 between the plane 221 and the ridgeline 33, and a gap 234 between the plane 222 and the ridgeline 34. Each has arisen. The gaps 231 to 234 are also called “play”.

  Next, the operation and effect of the wafer holding jig 10 according to the first embodiment will be described.

  (1) According to the first embodiment, by holding the crystal wafer 30 between the first groove 21 having a concave cross section and the second groove 22 having a concave cross section, the first groove 21 and the second groove 22 are retained. Since the corrosion-resistant film can be formed in a state where the ridge lines 31 to 34 of the quartz wafer 30 are in contact with each other, the wafer holding jig 10 does not cover the surface of the quartz wafer 30 when the corrosion-resistant film is formed. Therefore, by reducing the portion where the corrosion-resistant film is not formed during the formation of the corrosion-resistant film, cracks in the crystal wafer 30 due to the corrosion-resistant film forming process can be suppressed, so that the yield can be improved.

  (2) The concave shape of the cross section of the first groove 21 and the second groove 22 is not limited to the V shape, and may be, for example, a U shape, a semicircular shape, or a square shape. However, when the concave shape is V-shaped, each surface of the first groove 21 and the second groove 22 and each surface of the crystal wafer 30 are not too close to each other, so that the wafer holding It is possible to reliably prevent the jig 10 from covering the surface of the crystal wafer 30 when forming the corrosion resistant film.

  (3) When the crystal wafer 30 is held with the gaps 231 to 234 between the first groove 21 and the second groove 22, the following effects are exhibited. First, the presence of the gaps 231 to 234 makes it easy to insert the crystal wafer 30 between the first groove 21 and the second groove 22, thereby improving workability. Secondly, since the material of the corrosion-resistant film easily goes around the peripheral end surface of the crystal wafer 30 through the gaps 231 to 234 when forming the corrosion-resistant film, the wafer holding jig 10 covers the surface of the crystal wafer 30 when forming the corrosion-resistant film. This can be prevented more reliably.

  FIG. 3 [1] is a schematic view showing a part of the corrosion-resistant film forming method of the first embodiment, and FIG. 3 [2] is a perspective view showing a crystal wafer obtained by the corrosion-resistant film forming method of the first embodiment. . Hereinafter, the corrosion-resistant film forming method according to the first embodiment will be described with reference to FIGS.

  The corrosion resistant film forming method of the first embodiment is a corrosion resistant film forming method using the wafer holding jig 10 and includes the following steps. By inserting the crystal wafer 30 between the first groove 21 and the second groove 22 (FIG. 1 [1]), the crystal wafer 30 is held between the first groove 21 and the second groove 22 (FIG. 1). 1 [2]) step. In the state shown in FIG. 1 [2], a process of forming a corrosion-resistant film 36 on both surfaces of the quartz wafer 30 by sputtering or vapor deposition (sputtering in the first embodiment) (FIG. 3 [1] [2]). The corrosion resistant film 36 is composed of, for example, two layers of chromium and gold.

  As shown in FIG. 3 [1], for example, a magnetron sputtering apparatus 50 is used for forming the corrosion-resistant film. The magnetron sputtering apparatus 50 includes a vacuum chamber 51 that houses the crystal wafer 30 and the wafer holding jig 10, a valve 52 that introduces an inert gas into the vacuum chamber 51, a power source 53 that generates plasma in the vacuum chamber 51, and a vacuum chamber 51. A vacuum pump 54 for exhausting the inside is provided. Further, in the vacuum chamber 51, there are a fixing base 55 for fixing the crystal wafer 30 and the wafer holding jig 10, targets 56 and 57 made of the material of the corrosion-resistant film 36, magnets 58 and 58 attached to the targets 56 and 57, and the like. Contained.

  The targets 56 and 57 are placed one by one at positions facing both surfaces of the crystal wafer 30. When sputtering is used, the step coverage is good, and therefore the material that becomes the corrosion-resistant film 36 when forming the corrosion-resistant film passes through a fine gap (not limited to the gaps 231 to 234 (FIG. 2 [2])). It is easy to go around to the peripheral end surfaces 373 to 376 of the wafer 30 (FIG. 3 [2]).

  As shown in FIG. 3 [2], the crystal wafer 30 obtained by the corrosion-resistant film forming method of the first embodiment has all of the double-sided or two main surfaces 371 and 372 and the four peripheral end surfaces 373 to 376. A uniform corrosion-resistant film 36 is formed on the surface. Other configurations, operations, and effects of the corrosion-resistant film forming method of the first embodiment are the same as those of the wafer holding jig 10 of the first embodiment described above.

  FIG. 4 is a perspective view showing the wafer holding jig according to the second embodiment.

  The wafer holding jig 40 according to the second embodiment holds the crystal wafers 30 and 35 when a corrosion-resistant film serving as a wet etching mask is formed on the crystal wafers 30 and 35. The wafer holding jig 40 has a first holding piece 41 having a first groove 51 having a concave section (V-shaped in the second embodiment) and a first section 51 opposite to the first groove 51 and a concave section (this embodiment). 2, a second holding piece 42 having a second groove 52 having a V-shape), and the crystal wafers 30 and 35 are held between the first groove 51 and the second groove 52. In addition to the first holding piece 41 and the second holding piece 42, the wafer holding jig 40 includes a bottom plate 43 that fixes the first holding piece 41 and the second holding piece 42 in a state of standing parallel to each other. . In addition, about the wafer holding jig 40, only the part holding two crystal wafers 30 and 35 is shown in figure.

  In the second embodiment, a plurality of (two in the second embodiment) crystal wafers 30 and 35 are held between the first groove 51 and the second groove 52 with both surfaces exposed. That is, the lengths of the first holding piece 41 and the first groove 51 and the second holding piece 42 and the second groove 52 in the second embodiment are the same as the first holding piece 11 and the first groove 21 and the second length in the first embodiment. The length of the holding piece 12 and the second groove 22 (FIG. 1) is about twice. A spacer for providing an appropriate gap may be inserted between the crystal wafer 30 and the crystal wafer 35.

  According to the second embodiment, since the plurality of crystal wafers 30 and 35 can be held between the first groove 51 and the second groove 52, a corrosion-resistant film can be formed on many crystal wafers 30 and 35 at a time. Other configurations, operations, and effects of the second embodiment are the same as those of the first embodiment.

  Although the present invention has been described with reference to the above embodiments, the present invention is not limited to the above embodiments. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention. Further, the present invention includes a combination of some or all of the configurations of the above-described embodiments as appropriate.

DESCRIPTION OF SYMBOLS 10 Wafer holding jig 11 1st holding piece 12 2nd holding piece 13 Bottom plate 21 1st groove | channel 211,212 Plane 22 2nd groove | channel 221,222 Plane 231-234 Gap 30,35 Crystal wafer 31-34 Ridge line 36 Corrosion-resistant film 371, 372 Main surface 373-376 Peripheral end surface 40 Wafer holding jig 41 First holding piece 42 Second holding piece 43 Bottom plate 51 First groove 52 Second groove 50 Magnetron sputtering device 51 Vacuum chamber 52 Valve 53 Power supply 54 Vacuum pump 55 Fixing table 56 , 57 Target 58,58 Magnet

70 Quartz wafer 71 Corrosion resistant film 72 to 75 Clamped portion 72a to 75a Notch 76 Crack 80 Wafer holding jig 81 Outer frame portion 82 to 85 Claw portion

Claims (5)

In forming a corrosion resistant film as a mask for wet etching on a quartz wafer, in a wafer holding jig for holding the quartz wafer,
A first holding piece having a first groove having a concave cross section, and a second holding piece having a second groove having a concave cross section while facing the first groove,
The crystal wafer is held between the first groove and the second groove.
A wafer holding jig. The concave shape is V-shaped,
The wafer holding jig according to claim 1. The quartz wafer is held with a gap between the first groove and the second groove.
The wafer holding jig according to claim 1 or 2. A plurality of the quartz wafers are held between the first groove and the second groove in a state where both surfaces are exposed,
The wafer holding jig according to any one of claims 1 to 3. A method of forming a corrosion-resistant film using the wafer holding jig according to any one of claims 1 to 4,
By inserting the crystal wafer between the first groove and the second groove, the crystal wafer is held between the first groove and the second groove,
In this state, the corrosion-resistant film is formed on both surfaces of the quartz wafer by sputtering or vapor deposition.
A method for forming a corrosion-resistant film.

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