CROSS-REFERENCE TO RELATED APPLICATIONS

This application is 371 of International Patent Application No. PCT/JP2018/041723, filed Nov. 9, 2018, which claims the benefit of priority to Japanese Patent Application No. 2017-226096, filed Nov. 24, 2017, the contents of each of which is incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a method for removing a foreign substance adhering to a Fabry-Perot interference filter, and a method for manufacturing a light detection device.

BACKGROUND ART

In the related art, a Fabry-Perot interference filter including a substrate, a fixed mirror and a movable mirror facing each other via a gap on the substrate is known (for example, refer to Patent Literature 1).

CITATION LIST

Patent Literature

Patent Literature 1: Japanese Unexamined Patent Publication No. 2013-506154

SUMMARY OF INVENTION

Technical Problem

Since a Fabry-Perot interference filter has a relatively fragile movable mirror in a membrane shape, basically no attempt has been made to remove a foreign substance by a method that might cause deformation or breakage of the movable mirror. For this reason, the Fabry-Perot interference filter just having a foreign substance adhering to its surface has been treated as a faulty product in some cases, hindering improvement of the yield.

In view of this, the present disclosure aims to provide a method for removing a foreign substance and a method for manufacturing a light detection device capable of effectively removing a foreign substance adhering to a Fabry-Perot interference filter and improving a yield.

Solution to Problem

A method for removing a foreign substance according to an aspect of the present disclosure includes: a step of preparing a Fabry-Perot interference filter including a substrate having a first surface and a second surface opposite to the first surface, a first laminate having a first mirror portion arranged on the first surface, and a second laminate having a second mirror portion arranged on the first mirror portion, in which a gap is formed between a portion of the first laminate at least including the first mirror portion and a portion of the second laminate at least including the second mirror portion facing each other so that a distance between the first mirror portion and the second mirror portion facing each other varies by an electrostatic force; a step of detecting a foreign substance adhering to a surface of the second laminate opposite to the first laminate; and a step of blowing air in which an airflow peak position is adjusted on the basis of the position of the detected foreign substance onto the surface of the second laminate and thereby removing the foreign substance from the surface of the second laminate.

With the application of the method for removing a foreign substance according to one aspect of the present disclosure, a foreign substance adhering to the surface of the second laminate of a Fabry-Perot interference filter can be detected, and the foreign substance can be removed by blowing air. Since the airflow peak position of the air is adjusted on the basis of the position of the detected foreign substance, the foreign substance can be appropriately removed by blowing the air. As described above, according to the above-described method for removing a foreign substance, the foreign substance adhering to the Fabry-Perot interference filter can be effectively removed, and the Fabry-Perot interference filter can be obtained with high yield.

Here, the Fabry-Perot interference filter has a gap formed between a portion of the first laminate at least including the first mirror portion and a portion of the second laminate at least including the second mirror portion facing each other. That is, the portion of the second laminate overlapping the gap when viewed in the direction in which the first mirror portion and the second mirror portion face each other (hereinafter, simply referred to as a “membrane portion”) has a membrane structure, which makes this portion relatively vulnerable. This has discouraged attempts to remove a foreign substance using a method involving generation of a stress to be a load on the membrane portion and involving a concern of deformation or breakage in the membrane portion, and therefore, a Fabry-Perot interference filter to which a foreign substance adheres has often been treated as a faulty product. However, as a result of earnest and intensive research by the present inventors, it is confirmed that a method using air blow is capable of removing a foreign substance without affecting the characteristics of the Fabry-Perot interference filter even though this is a method of generating stress in the membrane portion.

In the step of removing a foreign substance, the airflow peak position may be adjusted to match the position of the foreign substance. In this case, since an airflow peak (that is, a portion where the air velocity is highest) directly hits the foreign substance, the foreign substance can be further reliably removed.

A plurality of through-holes may be formed from the surface of the second laminate to the gap, in a portion of the second laminate overlapping the gap when viewed in a direction in which the first mirror portion and the second mirror portion face each other, and the air may be blown onto at least a region of the surface of the second laminate where a plurality of through-holes is formed, in the step of removing a foreign substance. In this case, the air blown to the surface of the second laminate can be introduced into the gap via the plurality of through-holes. The air that has entered the gap is pushed out by air that newly enters the gap, so as to be discharged toward the surface of the second laminate via a through-hole that is different from the through-hole used as a passage of the air that newly enters the gap. In this manner, the foreign substance adhering to the surface of the second laminate can be blown up by the air discharged to the outside from the gap. This makes it possible to further effectively remove the foreign substance adhering to the Fabry-Perot interference filter.

In the step of preparing a Fabry-Perot interference filter, a wafer having a plurality of Fabry-Perot interference filters two-dimensionally linked to each other is prepared, and the step of detecting a foreign substance and the step of removing a foreign substance may be performed on the Fabry-Perot interference filter constituting the wafer. In this case, in a case where a foreign substance adheres to the Fabry-Perot interference filter constituting the wafer, the foreign substance can be removed by blowing air. With this configuration, in a case of inspecting each of a plurality of Fabry-Perot interference filters constituting a wafer, it is possible to transfer the Fabry-Perot interference filter from which a foreign substance has been removed to a subsequent process as a non-faulty product without immediately making a determination of faulty on the Fabry-Perot interference filter to which a foreign substance has adhered. Therefore, it is possible to improve the yield of the Fabry-Perot interference filter.

In the step of preparing a Fabry-Perot interference filter, singulated Fabry-Perot interference filters may be prepared. For example, in a case where foreign substance removal is performed by blowing air on a Fabry-Perot interference filter constituting a wafer including a plurality of Fabry-Perot interference filters, the foreign substance might scatter onto other Fabry-Perot interference filters constituting the wafer and might adversely affect the other Fabry-Perot interference filters. In contrast, by removing a foreign substance using air blow onto the Fabry-Perot interference filter at a stage where the Fabry-Perot interference filter is singulated as described above, it is possible to prevent occurrence of adverse effects to the other Fabry-Perot interference filters as described above.

A method for manufacturing a light detection device according to an aspect of the present disclosure is a method for manufacturing a light detection device including: a package having a cap formed with an opening through which light is incident and having a stein joined to the cap; a Fabry-Perot interference filter disposed in the package; and a light detector arranged in the package so as to detect light transmitted through the Fabry-Perot interference filter. The Fabry-Perot interference filter includes: a substrate having a first surface and a second surface opposite to the first surface; a first laminate having a first mirror portion arranged on the first surface; and a second laminate having a second mirror portion arranged on the first mirror portion, in which a gap is formed between a portion of the first laminate at least including the first mirror portion and a portion of the second laminate at least including the second mirror portion facing each other so that a distance between the first mirror portion and the second mirror portion facing each other varies by an electrostatic force. The manufacturing method includes: a step of preparing a stein to which the Fabry-Perot interference filter and the light detector are secured; a step of detecting a foreign substance adhering to a surface of the second laminate opposite to the first laminate of the Fabry-Perot interference filter secured to the stein; a step of blowing air in which an airflow peak position is adjusted on the basis of the position of the detected foreign substance onto the surface of the second laminate and thereby removing the foreign substance from the surface of the second laminate; and a step of joining the cap to the stein after the step of removing a foreign substance.

According to the method for manufacturing a light detection device, it is possible to detect a foreign substance adhering to the surface of the second laminate of the Fabry-Perot interference filter and possible to remove the foreign substance by air blow in a state where the Fabry-Perot interference filter and the light detector are secured to the stein. That is, it is possible to appropriately detect and remove foreign substance adhering to the Fabry-Perot interference filter immediately before acquisition of the light detection device. Here, since the assembling work of the light detection device is not always performed in a cleanroom with high cleanliness, the possibility of adhesion of a foreign substance to a surface of the Fabry-Perot interference filter during the assembling work can be relatively high. According to the above-described manufacturing method, it is possible to remove the foreign substance adhering to the Fabry-Perot interference filter in the final stage of the manufacturing process of the light detection device without significantly affecting the characteristics of the Fabry-Perot interference filter. This enables improvement of the yield of the light detection device, which is the final product, making it possible to obtain the light detection device with high yield.

A method for manufacturing a light detection device according to another aspect of the present disclosure is a method for manufacturing a light detection device including: a package having a lid substrate and a support body joined to the lid substrate; a Fabry-Perot interference filter disposed in the package; and a light detector disposed in the package so as to detect light transmitted through the Fabry-Perot interference filter. The Fabry-Perot interference filter includes: a substrate having a first surface and a second surface opposite to the first surface; a first laminate having a first mirror portion arranged on the first surface; and a second laminate having a second mirror portion arranged on the first mirror portion, in which a gap is formed between a portion of the first laminate at least including the first mirror portion and a portion of the second laminate at least including the second mirror portion facing each other so that a distance between the first mirror portion and the second mirror portion facing each other varies by an electrostatic force. The manufacturing method includes: a step of preparing a plurality of Fabry-Perot interference filters arranged one-dimensionally or two-dimensionally, a plurality of light detectors provided corresponding to the plurality of Fabry-Perot interference filters, and a support layer that is to support the plurality of Fabry-Perot interference filters and the plurality of light detectors and that is to be cut into a plurality of support bodies; a step of detecting a foreign substance adhering to a surface of the second laminate opposite to the first laminate for each of the plurality of Fabry-Perot interference filters; a step of blowing air in which an airflow peak position is adjusted on the basis of the position of the detected foreign substance onto the surface of the second laminate and thereby removing the foreign substance from the surface of the second laminate; a step of joining a lid substrate layer that is to be cut into a plurality of the lid substrates to the support layer after the step of removing a foreign substance and thereby obtaining a plurality of the light detection devices one-dimensionally or two-dimensionally linked to each other; and a step of cutting a portion at which the lid substrate layer and the support layer are joined and thereby obtaining each of the light detection devices.

According to the method for manufacturing a light detection device, it is possible to detect a foreign substance adhering to the surface of the second laminate of each of the Fabry-Perot interference filters and possible to remove the foreign substance by air blow in a state where a plurality of the Fabry-Perot interference filters is supported by the support layer. That is, it is possible to appropriately detect and remove foreign substance adhering to each of the Fabry-Perot interference filters immediately before acquisition of the light detection device. Therefore, according to the present manufacturing method, the effects similar to those of the above-described method for manufacturing a light detection device.

In the step of obtaining a plurality of light detection devices, the lid substrate layer having a plurality of openings formed in advance may be joined to the support layer such that each of the plurality of openings faces each of the plurality of Fabry-Perot interference filters. In this case, by using a lid substrate layer having a plurality of openings formed in advance, it is possible to obtain a light detection device having an opening for allowing incidence of light formed in the lid substrate immediately after cutting the lid substrate layer and the support layer. This makes it possible to omit a step for forming an opening in the lid substrate of each of the light detection devices after the cutting.

Advantageous Effects of Invention

According to the present disclosure, it is possible to provide a method for removing a foreign substance and a method for manufacturing a light detection device capable of effectively removing a foreign substance adhering to a Fabry-Perot interference filter and improving a yield.

