JP2005134524A - Silicon bench, manufacturing method therefor, and optical communication component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a silicon bench having a metal coat firmly pasted up to a silicon substrate. <P>SOLUTION: The silicon bench has a metal-mixed layer formed at least on a part of the silicon substrate surface, and a metal coat formed on the metal-mixed layer. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a silicon component having a metal coating and a method for manufacturing the same. More specifically, the present invention relates to a silicon bench having a metal film used as an element carrier and a method for manufacturing the same.

  With the spread of the Internet, it has become necessary to transmit and receive large amounts of information such as music, moving images, and computer data at high speed. In transmission / reception of data using an optical fiber, the transfer speed is 100 Mbps or more for home use, and data can be transmitted / received about three digits faster than a modem or ISDN using a telephone line that is widely used in general homes. Furthermore, it has reached 10 to 40 Gbps in the backbone system. In recent years, a new technology called optical multiplex communication has been introduced, and it is possible to further increase the speed and capacity. Under such circumstances, the demand for optical communication components is increasing, and cost reduction and reliability improvement are issues for component suppliers.

  In optical communication components, there is an element carrier (silicon bench or silicon bench) mainly composed of silicon (Si) for mounting or mounting a glass element such as an optical lens or an optical element such as an optical fiber or a laser diode. in use. An optical communication component using such a silicon bench is a central part in optical communication, and high reliability is required.

  Conventionally, when assembling the above optical communication parts, a lens or the like is mounted on a silicon bench, and both are fixed with an ultraviolet curable resin (for example, see Patent Document 1). However, this method did not cause any major problems at room temperature and humidity, but when exposed to high temperature and high humidity for a long time, there was a problem that the lens floated from the silicon bench and sometimes detached. . Therefore, it has been difficult to obtain long-term adhesion and airtightness between the lens and the silicon bench by the conventional ultraviolet curable resin bonding method.

  Therefore, it has been attempted to fix the lens or the like by metallic bonding (for example, soldering, welding, etc.) instead of fixing the lens or the like to the silicon bench with an ultraviolet curable resin. In order to fix by soldering or the like, it is necessary to provide a metal film such as Ni on a fixing portion between an element such as a lens and the silicon bench. An element such as a lens cannot be soldered to the silicon bench without interposing such a metal film. As a method for providing a metal film, there are physical vapor deposition methods such as vacuum vapor deposition and sputtering, and wet methods by electroless plating, but wet methods by electroless plating are overwhelmingly superior from the viewpoint of mass productivity.

  Patent Document 2 describes a method of electroless plating a NiP metal film on a magnetic recording medium glass substrate. According to this method, in order to improve the adhesion of the NiP electroless plating film to the glass substrate, the surface of the glass substrate is lapped using a polishing liquid composition containing silicon carbide particles or alumina particles. After performing the chemical etching process, the NiP electroless plating process must be performed.

  However, the method described in Patent Document 2 cannot provide a metal film having sufficient adhesion as an optical communication component. This is because the optical communication component requires very high durability for a long time. When a silicon bench, a lens, or the like is bonded by soldering or welding, the metal film is melted, so that a phenomenon in which the metal film peels occurs. This phenomenon is called “solder erosion”. In order to prevent solder erosion, the metal coating must have very strong adhesion and sufficient thickness.

JP-A-61-93419 Japanese Patent Laid-Open No. 11-203684

  Accordingly, an object of the present invention is to provide a silicon bench having a metal film firmly adhered to a silicon substrate and a method for manufacturing the same.

  As a means for solving the above-mentioned problem, a feature of the invention according to claim 1 is a silicon bench, which has a metal-mixed layer on at least a part of the surface of the silicon substrate, and a metal film is formed on the metal-mixed layer. Is to have.

  According to the invention according to claim 1 configured as described above, since the metal film is bonded to the silicon substrate via the metal mixed layer, the adhesion strength of the metal film to the silicon substrate is dramatically improved.

  As a means for solving the above-mentioned problem, a feature of the invention according to claim 2 is that the metal-mixed layer is formed by implantation of metal ions.

  According to the invention according to claim 2 configured as described above, the metal-mixed layer can be reliably and easily formed.

  As a means for solving the above problem, a feature of the invention according to claim 3 is that the metal ions to be implanted are metal ions having energy of 100 keV or more.

  According to the invention according to claim 3 configured as described above, the metal mixed layer formed on the silicon substrate has a sufficient thickness, and the silicon substrate and the metal film can be firmly bonded to each other.

  As a means for solving the above-mentioned problems, a feature of the invention according to claim 4 is that the metal ions to be implanted are Ni ions.

  According to the invention according to claim 4 configured as described above, a metal-mixed layer satisfactory for the silicon bench of the present invention can be formed.

  As a means for solving the above-mentioned problems, a feature of the invention according to claim 5 is that the metal coating is formed of a metal having good electrical conductivity, thermal conductivity and solder wettability.

  According to the invention according to claim 5 configured as described above, after mounting the optical communication element, the metal coating can be used as a heat dissipation film, a conductive path for electric signal output, etc. It can be done reliably.

  As a means for solving the above problem, a feature of the invention according to claim 6 is that the metal coating is formed of Au or a material mainly composed of an alloy of Au and Sn.

  According to the invention concerning Claim 6 comprised as mentioned above, all the requirements of electrical conductivity, heat conductivity, and solder wettability can be satisfy | filled.

  As a means for solving the above-mentioned problems, a feature of the invention according to claim 7 is that the metal coating is deposited by an electroless plating method.

  According to the invention concerning Claim 7 comprised as mentioned above, a metal film can be formed at low cost.

As a means for solving the above-mentioned problems, a feature of the invention according to claim 8 is a method for manufacturing a silicon bench, comprising: (1) preparing a silicon substrate;
(2) placing a mask having a predetermined opening pattern on the upper surface of the silicon substrate;
(3) forming a metal-mixed layer by implanting metal ions into the exposed surface of the silicon substrate through the mask;
(4) a step of depositing a metal film on the upper surface of the metal-mixed layer.

  According to the invention concerning Claim 8 comprised as mentioned above, a metal film adhere | attaches firmly with respect to a silicon substrate, and the silicon bench which shows the outstanding durability can be manufactured.

  As a means for solving the above problem, a feature of the invention according to claim 9 is that the metal coating is deposited by an electroless plating method.

  According to the invention concerning Claim 9 comprised as mentioned above, a metal film can be formed at low cost.

  As a means for solving the above-mentioned problem, the invention according to claim 10 is an optical communication component, and optical communication is performed via solder on the metal film of the silicon bench according to claim 1. It is that the element for joining was joined.

  According to the invention according to claim 10 configured as described above, the bonding between the optical communication element and the metal film is not broken even under a severe environment of high temperature and high humidity, and can be driven for a long period of time. Highly reliable optical communication parts can be obtained.

  By using a silicon bench having a metal mixed layer formed by metal implantation on at least a part of the surface of a silicon substrate and having a metal film deposited by electroless plating on the metal mixed layer, It is possible to exhibit extremely excellent bondability and durability between the metal film on the bench and an optical communication element such as a lens.

  FIG. 1 is a schematic sectional view of an example of a silicon bench according to the present invention. The silicon bench 1 of the present invention is basically formed from a silicon substrate 3. A groove 5 having a trapezoidal cross section is etched on one surface of the silicon substrate 3, and a metal mixed layer 7 is formed on the inner surface of the trapezoidal groove 5, and a metal film is deposited on the upper surface of the metal mixed layer 7. 9 In the silicon bench 1 of the present invention, the metal coating 9 is provided on the silicon substrate 3 via the metal-mixed layer 7, so that the adhesive strength of the metal coating 9 to the silicon substrate 3 is remarkably increased. The trapezoidal groove 5 is convenient for mounting a cylindrical optical communication element to be mounted. However, if the mounting element is a rectangular parallelepiped, the groove 5 is not necessarily required, and one surface of the silicon substrate is not necessary. It is also possible to provide the metal-mixed layer 7 directly on the plane and to form the metal film 9 on the upper surface of the metal-mixed layer 7.

  FIG. 2 is a process diagram illustrating a manufacturing process of the silicon bench shown in FIG. In FIG. 2A, a silicon substrate 3 having a groove 5 having a trapezoidal cross section on one surface is prepared. The width, depth, length, and the like of the groove 5 can be appropriately determined in consideration of the size of the element to be mounted in the groove. Such a groove 5 can be formed by etching the (100) surface of the silicon substrate 3 by a known and usual method such as etching. As an etching method, a reactive sputter etching method capable of anisotropic etching or a non-reactive ion etching method is preferable. Non-reactive ion etching includes sputter etching and ion beam etching. Needless to say, the groove 5 can be formed by isotropic etching according to its shape. As isotropic etching, both wet etching (chemical etching) and dry etching (reactive plasma etching) methods can be used. The groove 5 is not limited to a trapezoidal cross section as shown, but may be a V-shaped groove. When the (100) plane of the silicon substrate is anisotropically etched, directionality occurs in the etching, so that a trapezoidal groove or a V-shaped groove as shown in the figure is formed. A groove having a trapezoidal or V-shaped cross section formed by such anisotropic etching is advantageous because elements such as a lens can be stably inserted into the groove. If the groove 5 is unnecessary, a silicon substrate without the groove 5 may be prepared.

  In FIG. 2 (2), a mask 17 having a predetermined opening pattern is placed on the upper surface of the trapezoidal groove 5 of the silicon substrate 3. Next, in FIG. 2 (3), metal ions are implanted into the exposed surface of the trapezoidal groove 5 through the opening pattern of the mask 17. The ion implanter itself used for implanting metal ions in the present invention is known to those skilled in the art. The ion implanter is sometimes called an ion implanter. Such an ion implantation apparatus has an acceleration voltage of 10 to 400 keV, a beam current of nA to 10 mA, and a small current type (˜100 μA), a medium current type (˜500 μA), a large current type (˜ 1 mA) and predeposition type (-10 mA). In principle, any metal ion can be used as long as it is a metal ion capable of forming a solid solution with the silicon of the substrate. However, generally, it is preferable to use a metal ion having a high energy of 100 keV or higher as the metal ion to be implanted. When metal ions having low energy are implanted into the silicon substrate, the metal mixed layer 7 becomes incomplete, and the silicon substrate 3 and the metal coating 9 cannot be formed with sufficient adhesion. Therefore, the metal ions to be implanted are preferably Ni, Pd, Au, or the like. Since metal ions having a large atomic weight such as Au must give a large acceleration energy, a large ion implantation apparatus is required, so Ni is particularly preferable from the viewpoint of industrial productivity. FIG. 4 shows the relationship between atomic weight and implantation depth with respect to metal ion energy. As shown in FIG. 4, Ni can form a metal-mixed layer having a depth of 100 nm to 200 nm with an ion beam intensity of 100 keV. In the case of Au, an ion beam intensity of 500 keV is required to form a metal-mixed layer having a depth of 100 nm to 200 nm. From this result, it can be understood that Ni is particularly preferable.

  As shown in FIG. 2 (4), a metal mixed layer 7 is formed on the inner wall surface of the trapezoidal groove 5 of the silicon substrate 3 by metal ion implantation. The thickness of the metal-mixed layer 7 is preferably in the range of 100 nm to 200 nm. When the film thickness of the metal mixed layer 7 is less than 100 nm, the effect of improving the adhesion between the silicon substrate 3 and the metal coating 9 is insufficient. On the other hand, when the film thickness of the metal-mixed layer 7 exceeds 200 nm, the effect of improving the adhesion between the silicon substrate 3 and the metal coating 9 is saturated, and the silicon substrate 3 becomes brittle.

  Next, after removing the mask 17, as shown in FIG. 2 (5), the metal film 9 is formed on the upper surface of the metal mixed layer 7 to complete the silicon bench 1 of the present invention. Even if the metal coating 9 is directly formed on the silicon substrate 3, the adhesion of the metal coating 9 itself to the silicon substrate 3 is extremely weak, so the metal coating 9 must be provided on the silicon substrate 3 via the metal-mixed layer 7. From the viewpoint of mass productivity, it is preferable that the metal coating 9 be adhered by an electroless plating method. The metal coating 9 is preferably formed from a material whose main component is a metal having good electrical conductivity or thermal conductivity. Similarly, the metal coating 9 is preferably a metal with high solder wettability. Examples of the material for forming the metal film 9 that simultaneously satisfies the requirements of both electrical conductivity or thermal conductivity and solder wettability include a material mainly composed of Au or an alloy of Au and Sn. The electroless plating method itself is known to those skilled in the art and will not require any particular explanation. In general, the thickness of the metal coating 9 is preferably in the range of 50 nm to 1 μm. When the thickness of the metal coating 9 is less than 50 nm, the electrical conductivity or thermal conductivity improvement effect and the solder wettability improvement effect are not sufficient, and it may cause inconvenience in the bonding of mounting elements, which is preferable. Absent. On the other hand, when the film thickness of the metal coating 9 exceeds 1 μm, the effect of improving the electrical conductivity or thermal conductivity, the effect of improving the wettability of the solder, and the effect of improving the bonding property of the mounting element are saturated, which is only uneconomical.

  FIG. 3 is a schematic cross-sectional view showing a state in which a mounting element (for example, an optical lens) 11 is firmly fixed to the silicon bench 1 shown in FIG. Fixing by metallic connection refers to fixing by soldering, welding, or the like, for example. Soldering is excellent in that it can be fixed with a simple device. In the embodiment shown in FIG. 3, the mounting element (optical lens) 11 is bonded to the metal film 9 of the silicon bench 1 via the solder layer 15. Thus, the mounting element (optical lens) 11 can be stably supported on the silicon bench 1 for a long period of time. In order to assist the bonding by the solder layer 15, it is preferable to form the metallized layer 13 on the outer surface of the mounting element (optical lens) 11.

  As a material for forming the solder layer 15, a known and commonly used solder material as defined in JIS / H4341 can be appropriately selected and used. For example, a PbSn alloy and an alloy solder material containing a small amount of a low melting metal such as Bi or Sn are preferable. These solder materials have a melting point of about 300 ° C. at the highest, and there is no fear of adversely affecting the silicon bench 1 or the mounting element 11.

  As a method of metallizing the outer surface of the mounting element 11, there are a physical vapor deposition method such as vacuum vapor deposition and sputtering, and a wet method using electroless plating. There are various types of mounting elements such as a cylinder and a rectangular parallelepiped, and when mass productivity is taken into consideration, it is difficult to perform metallization over the entire outer periphery of the mounting element of the cylinder and the rectangular parallelepiped by physical vapor deposition. Therefore, the wet method by electroless plating that can immerse the entire surface of the mounting element quartz ferrule is overwhelmingly superior from the viewpoint of mass productivity.

  When the outer surface of the mounting element 11 is metallized by an electroless plating method, for example, the mounting element is immersed in a substitutional electroless gold plating bath, and a gold or gold alloy (for example, AuSn) film is plated on the outer surface of the mounting element. The adhesion film thickness of the gold or gold alloy film can be controlled, for example, by adjusting the immersion time of the mounting element 11 in the electroless plating bath. Since the mounting element 11 is a glass product such as an optical lens, an optical fiber, a quartz ferrule, etc., and the adhesion force of the gold or gold alloy film to the glass surface is extremely weak, for example, the Ni alloy film is first used as an underlayer. Then, it is preferable to deposit gold or a gold alloy film on the outer surface of the Ni alloy base film. In order to prevent “solder erosion”, the thickness of the Ni alloy underlayer is preferably 1 μm or more.

  In FIG. 3, in addition to the optical lens, various elements such as an optical fiber, a laser diode, an optical switch, a semiconductor, a capacitor, and a photoelectric conversion element can be mounted as the mounting element 11. In particular, when an active element such as a laser diode is mounted, heat generation becomes a problem. Long-term use may cause malfunction due to heat. Since the metal coating 9 is present in the silicon bench 1 of the present invention, the metal coating 9 can be used as a heat dissipation film so as to efficiently release heat from the silicon substrate 3. Thereby, the optical communication component produced by mounting the optical communication element on the silicon bench 1 can be stably driven for a long time, and high durability can be maintained. When the mounting element is a photoelectric conversion element, the metal coating 9 can also be used as a conductive path for outputting an electric signal of the photoelectric conversion element.

Example 1
An anisotropic etching process was performed on a silicon substrate having a thickness of 1.5 mm and a (100) plane, and a groove having a trapezoidal cross section with a width of 1000 μm, a depth of 500 μm, and a length of 5 mm was etched. In the trapezoidal groove portion, a metal-mixed layer and a metal film were formed by the following procedure.
(1) Formation of metal-mixed layer A portion of the silicon substrate other than the trapezoidal groove was masked, and Ni ions were implanted using a 200 keV ion implanter.
(2) Metal film deposition process After washing with water, the silicon substrate is immersed for 5 minutes in a substitution type electroless Au plating solution Muden Noble AU manufactured by Okuno Pharmaceutical Co., Ltd. with a bath temperature of 65 ° C., and a metal film (Au film) is provided. A bench was made.
A cross-sectional SEM image in the vicinity of the surface layer was observed at the boundary between the metal film of the obtained silicon bench and the silicon substrate. In the vicinity of the boundary portion, a mixed layer in which metal is mixed in silicon was formed. A peel test was conducted on the metal coating portion using a mending tape 810 manufactured by Scotch, but no film peeling occurred.
In addition, an optical lens having a metallized layer on the outer surface was mounted on the trapezoidal groove of the silicon bench and fixed with solder. Although it was left for 100 hours in an environment of 150 ° C. and 90% RH, no phenomenon such as peeling of the metal film, cracking of the solder, dropping of the optical lens, etc. was observed.

Comparative Example 1
A silicon substrate having a trapezoidal groove similar to that of Example 1 was prepared, and a mask was applied to portions other than the trapezoidal groove. Thereafter, using a sputtering method, a Ti / Pt layer was formed as an underlayer, a metal film made of Au was formed through the underlayer, and a silicon bench was produced. A peel test was performed in the same manner as in Example 1, but no peeling of the Au metal film occurred.
Further, when an optical lens having a metallized layer was mounted on the outer surface of the trapezoidal groove of the silicon bench and was fixed by soldering, the Au metal film peeled off. It has been found that when the underlayer is formed by a normal film forming method, the adhesion strength between the silicon substrate and the metal film is weak, which causes a problem at high temperatures.

  An optical communication component manufactured by mounting an optical communication element such as an optical lens or a laser diode on the silicon bench of the present invention can be used continuously for a long time in a high temperature and high humidity environment. It has durability. Therefore, high reliability is exhibited even in a very severe situation that cannot be handled by conventional optical communication components, and it can be used in a wide range of industrial applications.

It is outline | summary sectional drawing of an example of the silicon bench of this invention. It is process drawing explaining an example of the manufacturing process of the silicon bench shown by FIG. It is a schematic sectional drawing which shows the state which mounted the optical lens in the silicon bench shown by FIG. It is a characteristic view which shows the relationship between atomic weight with respect to metal ion energy, and implantation depth.

Explanation of symbols

1 Silicon Bench of the Present Invention 3 Silicon Substrate 5 Trapezoidal Groove 7 Metal Mixed Layer 9 Metal Film 11 Optical Lens 13 Metallized Layer 15 Solder Layer 17 Mask

Claims (10)

A silicon bench comprising a metal-containing layer on at least a part of a surface of a silicon substrate, and a metal film on the metal-containing layer. The silicon bench according to claim 1, wherein the metal-mixed layer is formed by implanting metal ions. The silicon bench according to claim 2, wherein the metal ions to be implanted are metal ions having energy of 100 keV or more. 4. The silicon bench according to claim 2, wherein the metal ions to be implanted are Ni ions. 2. The silicon bench according to claim 1, wherein the metal coating is made of a metal having good electrical conductivity, thermal conductivity, and solder wettability. 6. The silicon bench according to claim 1, wherein the metal coating is made of a material mainly composed of Au or an alloy of Au and Sn. The silicon bench according to claim 1, 5 or 6, wherein the metal coating is deposited by an electroless plating method. (1) preparing a silicon substrate;
(2) placing a mask having a predetermined opening pattern on the upper surface of the silicon substrate;
(3) forming a metal-mixed layer by implanting metal ions into the exposed surface of the silicon substrate through the mask;
(4) A method for producing a silicon bench, comprising the step of depositing a metal film on the upper surface of the metal-containing layer. The manufacturing method according to claim 8, wherein the metal coating is deposited by an electroless plating method. An optical communication component comprising an optical communication element joined to the metal film of the silicon bench according to claim 1 via solder.

Images