JPH07162098A - Method for automatically positioning optical device array to optical fiber - Google Patents

Abstract

PURPOSE:To position an optical device array to optical fibers with no adjustment by engaging two Si substrates processed by special anisotropic etching and by patterning V grooves to attach optical fibers in place and pads and lead terminals to attach an optical device array. CONSTITUTION:An engagement recess 25, V grooves to fix optical fibers at right angles from this recess 25, lead terminals 27, and solder pads 28 are formed on a (100) Si substrate 22. The side walls of the recess 25 and the V grooves 26 cross the substrate 22 face at 54.74 deg.. On the other hand, a recess 29 provided in a (110) Si substrate 23 has a (111) face which crosses the substrate 23 face at 35.26 deg. and a (111) face which crosses it at 90 deg.. A microlens array 30 for LD array use is formed at the middle position of the recess 29 of the Si substrate 23. After both substrates are diced into chips, both the substrates 22,23 are engaged, and an LD array 32 is attached to the position of a solder pad 28, and optical fibers 33 are inserted into V grooves 26 to fix.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for automatically positioning an optical element array and an optical fiber which can position the optical element array and the optical fiber without adjustment.

In the field of information processing in recent years, it has been necessary to speed up and increase the capacity of arithmetic processing. To realize this, optical parallel transmission is necessary, and a laser diode array (LD) is required.
Arrays, photodiode arrays (PD arrays) and optical fibers, optical waveguides, etc. must be aligned with high precision.

[0003]

2. Description of the Related Art FIG. 8 shows a conventional method for aligning an LD array 1 and an optical fiber array 3 composed of a plurality of optical fibers 2. The LD array 1 and the optical fiber array 3 can be soldered to each other. The blocks 4 and 5 are adhesively fixed, and each block 4 and 5 is provided with two handles 6 and 7, and is placed on the substrate 9 via the solder layer 8 to energize the heater 10. The substrate 9 is slidably formed by heating the substrate 9 to a temperature above the melting point of the solder.

Here, the optical fiber array 3 is provided with a plurality of grooves for fixing the optical fiber 2, which are formed by selectively etching a silicon (Si) substrate, cutting a metal, or made of ceramics. Multiple optical fibers 2
(8 pieces in this case) are inserted and fixed by adhesion using a lid of the same shape from above.
Eight optical fibers 2 forming the optical fiber array 3 with D
It is not easy to accurately position and, because the substrate 9 is heated to melt the solder layer 8 and the blocks 4 and 5 can be slid while observing with a stereoscopic microscope.
A method has been adopted in which the substrate 9 is finely adjusted and aligned while confirming optical coupling, and the substrate 9 is cooled and fixed. As described above, since the alignment requires a delicate and complicated process, it is difficult to reduce the cost.

[0005]

In the positioning of the optical element array and the optical fiber array, conventionally, the position is adjusted and fixed while confirming the optical coupling of each element, so that it is not suitable for mass production. , It is difficult to reduce the price. Therefore, it is an issue to put into practical use a positioning method that does not require such optical axis adjustment.

[0006]

[Means for Solving the Problems] [100]
Is used as a mask, and the silicon oxide film formed on the second silicon substrate having (110) as the substrate surface is used as a mask to anisotropically etch each silicon substrate to form the first silicon substrate. For the silicon substrate, a female type or a male type having a (111) surface as a side wall that intersects the substrate surface at 54.74 degrees,
On the second silicon substrate, make a male or female mold having a (111) plane that intersects the substrate plane at 35.26 degrees at 90 degrees and a (111) plane that intersects at 90 degrees on the side wall, and the optical element array on this substrate. A plurality of V-grooves for patterning a pad and lead terminals for mounting the optical fiber and for fixing an optical fiber, mounting an optical element array on the pad, and then mounting the optical element array on the first silicon substrate and the second silicon substrate respectively. This can be solved by configuring an automatic positioning method for the optical element array and the optical fiber, which is characterized by mounting the optical fiber in the V groove after the side walls of the mold are abutted and vertically fitted.

[0007]

The function of the present invention is photolithography (photolithography).
And two Si substrates are processed by using the anisotropic etching technology peculiar to the Si single crystal substrate, and the two substrates are engaged with each other, and the V-groove and the optical fiber for mounting the optical fiber at the position determined by the photo-etching technology are processed. By patterning the pad and the lead terminal for mounting the element array, the adjustment of the optical axis becomes unnecessary.

That is, at present, a photo-etching technique using a photoresist and exposure to ultraviolet rays or excimer laser can form a pattern with an accuracy of μm, and Si is a silicon dioxide (Excellent chemical resistance by heating in the atmosphere). A SiO ₂ ) film can be formed on the surface of the substrate and this film can be used as a mask during the chemical etching process.

Next, the anisotropic etching peculiar to the Si single crystal substrate utilizes the phenomenon that the etching rate varies depending on the crystal orientation of the Si crystal. By selecting an etching solution, the crystal plane with the slowest etching rate can be used. That is (11
1) The surface can be exposed on the surface, and the substrate can be processed into various shapes by utilizing the crystal orientation dependence of the etching rate.

That is, there are isotropic etching liquids and anisotropic etching liquids as Si etching liquids. The former representative liquids are hydrofluoric acid (HF), nitric acid (HNO ₃ ) and acetic acid (CH ₃ COOH). It is a mixed solution and is formed mainly of strong acid, and is etched at a uniform rate with respect to all crystal orientations. On the other hand, the latter is potassium hydroxide (KOH) and sodium hydroxide (N
aOH) is a weaker etching solution than the former such as each aqueous solution or a mixed solution of ethylenediamine and pyrocatechol. When this solution is used, the etching rate can be changed depending on the crystal orientation, and the (110) plane is the fastest, 100)
The surface is slow and the (111) surface can be hardly etched.
The Si substrate can be processed precisely and finely.

Now, utilizing the latter technique,
Sensors such as pressure sensors and acceleration sensors, and micromechanical devices (fine mechanical elements) such as nozzles and connectors have been developed. The present invention utilizes this technique to position the optical array element and the optical fiber array without adjusting the optical axis.

1 to 4 are principle diagrams according to the present invention. In each case, two substrates having crystal orientations of (100) plane and (110) plane are used, and a photo-etching technique and an anisotropic etching technique are used. The substrate is processed by using to form various recesses and grooves, and the recesses and grooves are used to vertically engage the two substrates to perform positioning with extremely high accuracy.

The method for each drawing will be described below. In FIG. 1, FIG. 1A shows a Si substrate 12 having a (100) surface [abbreviated as (100) Si substrate], and FIG. 1B shows a Si substrate 13 having a (110) surface. Hereinafter, (110) Si substrate]. First, a resist is coated on a (100) Si substrate 12 shown in FIG. 3A, a SiO ₂ film is opened so that a T-shaped convex portion remains in the central portion, and then a predetermined depth is reached. When anisotropic etching is performed, a recess having (100) as the bottom surface 14 and the side wall 15 as the (111) surface is formed. In this case, the side wall 15 has six surfaces (A, B, C in the figure,
D, E, F) and intersects the bottom surface (14) at 54.74 degrees, but the orientations of the crystal planes are A, B, D, and F. (A, C, E are the same) On the other hand, the entire surface of the (110) Si substrate 13 is coated with a resist,
After forming a wedge-shaped resist window having a width equal to that of the T-shaped convex portion of FIG. 9A at the end portion, and also opening the resist at the end portion on the back surface to remove both SiO ₂ films. When anisotropic etching is performed until the end reaches a predetermined depth, the same figure (B)
As shown in, a concave portion having a (111) plane as a bottom surface and a side surface is formed. In this case, the bottom surface (G and J) is (110).
It intersects the substrate plane at 35.26 degrees, and the H and I planes intersect the (110) substrate plane at 90 degrees.

Next, when the two substrates (12, 13) are joined together, the two substrates can be accurately vertically engaged with each other as shown in FIG. 11C, and the optical device is placed on both substrates. If it is formed, the alignment of the two becomes unnecessary. Note that FIG. 3D is a front view showing a bonded state of the (100) Si substrate 12 and the (110) Si substrate 13.

FIG. 2 shows another combination method. As a result of anisotropically etching the (100) Si substrate 16 and the (110) Si substrate 17 by the same method, both of the crystal planes (111) appear. ) Surface, but K, which appears in FIG.
The 6 planes of L, M, N, O, and P all intersect with the bottom plane consisting of (100) planes at 54.74 degrees, but the orientation of the crystal planes consists of K, L, N, and P types. There is. (K, M, O
Are the same) In addition, among the etching surfaces that appear on the (110) Si substrate 17 in FIG. 1B, three surfaces Q, T, and U are the (110) substrate surface.
They intersect at 35.26 degrees, and there are two types of crystal plane orientations, Q and U, and the R and S planes intersect with the (110) substrate plane at 90 degrees, and the crystal orientations are different. And (10
When (0) Si substrate 16 and (110) Si substrate 17 are joined together, they can be vertically engaged as shown in FIG. 2C, and if optical devices are formed on both substrates, they will be aligned with each other. It becomes unnecessary.

FIG. 3 shows another combination method, in which the (100) Si substrate 18 and the (110) Si substrate 19 are anisotropically etched by the same method. In FIG. 6 faces of a, b, c, d, e, f that appear are (100)
It intersects with the bottom consisting of planes at 54.74 degrees, but the orientation of the crystal plane consists of four types: a, b, d, and f. (A,
(c and e are the same) In addition, among the etching surfaces appearing on the (110) Si substrate 19 in FIG. 2B, three surfaces g, j, and k are the (110) substrate surface.
They intersect at 35.26 degrees, and there are two types of crystal plane orientations, g and k, and the h plane and the i plane intersect with the (110) substrate plane at 90 degrees, and the crystal orientations are different. And (10
(0) When the (110) Si substrate 19 is joined to the Si substrate 18, they can be vertically engaged with each other as shown in (C) of the figure. If optical devices are formed on both substrates, they can be aligned with each other. It becomes unnecessary.

FIG. 4 shows another combination method, in which the (100) Si substrate 20 and the (110) Si substrate 21 are anisotropically etched by the same method. Is anisotropically etched from both front and back sides, and l, m, n, o, p, q, r, which appear in FIG.
10 planes of s, t, and u are the substrate plane consisting of (100) plane and 54.7
Although they intersect at 4 degrees, the crystal plane orientations are l, m, n, and o.
It consists of four types.

In the etching surface appearing on the (110) Si substrate 21 in FIG. 2B, v and x intersect the (110) substrate surface at 35.26 degrees, and w, y, z, and α. Each plane intersects the (110) substrate plane at 90 degrees, and the crystal orientation is v, x,
It consists of four types represented by w and z. (W and α,
(z and y are the same) and (11) on the (100) Si substrate 20.
0) When the Si substrates 21 are joined, they can be vertically engaged with each other as shown in FIG. 7C, and if optical devices are formed on both substrates, the alignment of the two becomes unnecessary.

The present invention provides an optical device which does not require optical axis adjustment by adopting a method of anisotropically etching and processing a (100) Si substrate and a (110) Si substrate, and engaging them with each other. To form.

[0020]

EXAMPLE Example 1 (bonding of LD array and optical fiber, corresponding to FIG. 5) (100) Si substrate 22 and (110) Si substrate having a thickness of 1 mm
Photograph of 23 is heated to 1000 ° C in the atmosphere, a SiO ₂ film 24 with a thickness of about 1 μm is formed on the surface of this substrate, and then a positive resist (product name OFPR, made by Tokyo Ohka) and selective exposure of ultraviolet rays are performed. A window is opened in the resist in the region where anisotropic etching is to be performed using the etching technique, and this substrate is set in a reactive ion etching (RIE) device, and carbon tetrafluoride (C
Etching is performed with a mixed gas of F ₄ ) and hydrogen (H ₂ ) as an etchant, and the SiO ₂ film 24 in the region where anisotropic etching is performed is performed.
Except for that, the Si substrate in that portion was exposed. At this time, the SiO ₂ film at the symmetrical position on the back surface of the (110) Si substrate 24 is also removed. (A and a in FIG. 4 above) Next, as an etchant for anisotropic etching, a solution of potassium hydroxide (KOH), isopropyl alcohol (abbreviated as IPA) and water (H ₂ O) is used. To (1
By immersing the (00) Si substrate 22 and the (110) Si substrate 23, at least three recesses 25 for engagement are formed on the (100) Si substrate 22 as shown in FIG.
Four V-grooves 26 for fixing the optical fiber were formed at a right angle. Here, both the recess 25 and the side wall of the V groove 26 intersect the (100) substrate surface at 54.74 degrees.

On the other hand, the recess 29 provided in the (110) Si substrate 23.
Intersects the (110) substrate surface at 35.26 degrees (111)
It is composed of a (111) plane that intersects the plane at 90 degrees. Next, four lead terminals 27 and four solder pads 28 were formed adjacent to the central recess 25 of the (100) Si substrate 22. Here, the lead terminal 27 is patterned by photolithography after forming a thin film of gold (Au) on the (100) Si substrate 22 by the electron beam evaporation method, and the solder pad 28 is coated with a resist. After that, a window is opened at this position, and after forming a gold / tin (Au-Sn) solder film by the resistance heating vapor deposition method,
It was formed by lift-off.

On the (110) Si substrate 23, a microlens array 30 for an LD array to be mounted later is formed at an intermediate position between the two recesses 29. This forming method has four lens forming positions. The (110) Si substrate 23 was formed by ion beam etching while leaving the resist in the concave portion 29 and performing heat treatment to condense the resist at the lens forming position into a convex shape. (The above C and c in the same figure) Next, after cutting both boards at the position of the broken line 31 to make them into elements as shown in D and d in the same figure, both boards 22 and 23 are meshed, and the position of solder pad 28 If the LD array 32 is correctly mounted on the optical fiber 33 and the optical fiber 33 is inserted into the V groove 26 and fixed, the LD array 32 and the plurality (four in this case) of optical fibers 33 are positioned via the microlens array 30. Be matched. Example 2 (Joining LD Array and Optical Fiber, Corresponding to FIG. 6) Similarly to Example 1, the (100) Si substrate 35 and the (110) Si substrate 36 were subjected to anisotropic etching, and as shown in FIG. ) And (B)
Processed as shown in (1), a (37) Si substrate 35 was formed with a recess 37 for engagement and four V grooves 38, and (11)
0) Lead terminals 39 are formed on the surface of the Si substrate 36 as in the first embodiment.
Four solder pads 40 and four solder pads were formed and cut into a predetermined size. Further, since wiring connection is difficult in the unit element composed of the (110) Si substrate 36 shown in FIG. 6B, the auxiliary electrode made of ceramics in which the extraction electrode 41 is patterned as shown in FIG. The part 42 is provided.

First, as shown in FIG.
0) After mounting the LD array 43 at the position of the solder pad 40 of the Si substrate 36, the LD array 43 is engaged with the (100) Si substrate 35 to be joined, and the optical fiber 44 is inserted into the V groove 38 of the (100) Si substrate 35. Further, by wire-bonding the lead terminal 39 of the (110) Si substrate 36 and the lead-out electrode 41 of the auxiliary component 42 to each other, unadjusted bonding could be performed as shown in FIG. Example 3: (Joining of LD array and optical fiber, corresponding to FIG. 7) Anisotropic etching was performed on the front and back surfaces of the (100) Si substrate 46 in the same manner as in Example 1, and the surface of FIG. As shown in (), a large trapezoidal convex portion 47 and small convex portions 48 and 49 are formed. Here, all the sidewalls of the protrusion intersect with the (100) substrate surface at 54.74 degrees. The large convex portion 47 is the position where the microlens array is formed, and four holes 50 are formed behind the position where the microlens is formed, as shown in FIG. Are both (10
0) It intersects with the board surface at 54.74 degrees. Next, the first embodiment is formed on the large convex portion 47 on the substrate surface corresponding to these four holes.
A microlens array 52 consisting of four lenses was formed by the same method as above (C in the same figure). Next, the (110) Si substrate 54 was anisotropically etched in the same manner as in the conventional method, and the surface was Has a large recess 55 and small recesses 56, 57 on the back surface. Here, the bottoms of the three recesses intersect the (110) substrate surface at 35.26 degrees and the sidewalls intersect at 90 degrees. Next, the lead terminals 58 for mounting the LD array and the solder pads 59 were formed on the surface of the (110) Si substrate 54 by the same method as in the first embodiment. (A in the same figure) Next, the combination of the (100) substrate 46 and the (110) Si substrate 54 is the same as the large convex portion 47 and the small convex portion 4 of the (100) substrate 46.
Both substrates are fixed by fitting the large concave portion 55 and the small concave portions 56 and 57 of the (110) Si substrate 54 into the side wall portions 8 and 49 facing each other. FIG. 3D shows a state in which the LD array 43 is mounted on the (100) substrate 46.
If the optical fiber 44 is inserted into the hole 50 on the back surface of the LD array 43, the LD array 43 is positioned without adjustment. FIG. 6E shows this state by changing the direction.

[0024]

By implementing the present invention, highly accurate alignment between the optical element array and the optical fiber can be performed without adjustment.

[Brief description of drawings]

FIG. 1 is a diagram (1) of a meshing principle according to the present invention.

FIG. 2 is a diagram (part 2) of the principle of engagement according to the present invention.

FIG. 3 is a diagram (Part 3) of the principle of engagement according to the present invention.

FIG. 4 is a principle diagram (Part 4) of the engagement according to the present invention.

FIG. 5 is an explanatory diagram of an embodiment (No. 1) of the present invention.

FIG. 6 is an explanatory diagram of an embodiment (2) of the present invention.

FIG. 7 is an explanatory diagram of an embodiment (3) of the present invention.

FIG. 8 is a perspective view showing a conventional alignment method.

[Explanation of symbols]

1, 32, 43, LD array 2, 33, 44, optical fiber 3 Optical fiber array 12, 16, 18, 20, 22, 35, 46, (100) Si substrate 13, 17, 19, 21, 23, 36 , 54, (110) Si substrate 24 SiO ₂ film 25, 29, recesses 27, 39, lead terminals 28, 40, solder pads 30, 52, microlens array

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location H01L 31/0232

Claims (1)

[Claims] 1. Anisotropic silicon substrates using a silicon oxide film formed on a first silicon substrate having (100) as a substrate surface and a second silicon substrate having (110) as a substrate surface as a mask. Of the first or second silicon substrate, which has a (111) face on its side wall, which intersects the substrate surface at 54.74 degrees, and the second silicon substrate, intersects the substrate surface at 35.26 degrees. A male mold or a female mold having a (111) plane that intersects the (111) plane at 90 degrees on a side wall is formed, and a pad for mounting an optical element array and a lead terminal are formed on the substrate and an optical fiber is formed. After providing a plurality of V-grooves for fixing and mounting the optical element array on the pads, the side walls of the respective molds provided on the first silicon substrate and the second silicon substrate are abutted and vertically fitted. And then insert the optical fiber into the V groove. Automatic positioning method of the optical element array and the optical fiber, characterized in that the wear.