KR100275863B1 - Structure of a filter for infrared sensor - Google Patents
Structure of a filter for infrared sensor Download PDFInfo
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- KR100275863B1 KR100275863B1 KR1019920015222A KR920015222A KR100275863B1 KR 100275863 B1 KR100275863 B1 KR 100275863B1 KR 1019920015222 A KR1019920015222 A KR 1019920015222A KR 920015222 A KR920015222 A KR 920015222A KR 100275863 B1 KR100275863 B1 KR 100275863B1
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- Prior art keywords
- filter
- wafer
- infrared
- thickness
- infrared sensor
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- 239000010409 thin film Substances 0.000 claims description 2
- 238000005498 polishing Methods 0.000 abstract description 3
- 230000005855 radiation Effects 0.000 abstract description 3
- 229910052710 silicon Inorganic materials 0.000 abstract description 3
- 230000005540 biological transmission Effects 0.000 abstract description 2
- 238000000034 method Methods 0.000 abstract description 2
- 229910052581 Si3N4 Inorganic materials 0.000 abstract 2
- 238000000623 plasma-assisted chemical vapour deposition Methods 0.000 abstract 2
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 abstract 1
- 239000010703 silicon Substances 0.000 abstract 1
- 238000002834 transmittance Methods 0.000 description 10
- 238000004519 manufacturing process Methods 0.000 description 7
- 239000010408 film Substances 0.000 description 5
- 238000010586 diagram Methods 0.000 description 4
- 239000006096 absorbing agent Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 1
- 238000005229 chemical vapour deposition Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 230000007257 malfunction Effects 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 230000010287 polarization Effects 0.000 description 1
- 238000007517 polishing process Methods 0.000 description 1
- 230000002269 spontaneous effect Effects 0.000 description 1
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/20—Filters
- G02B5/28—Interference filters
- G02B5/281—Interference filters designed for the infrared light
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
- H01L27/14—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation
- H01L27/144—Devices controlled by radiation
- H01L27/146—Imager structures
- H01L27/14643—Photodiode arrays; MOS imagers
- H01L27/14649—Infrared imagers
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Pressure Sensors (AREA)
- Photometry And Measurement Of Optical Pulse Characteristics (AREA)
Abstract
Description
제1도는 종래의 적외선 센서와 적외선 감지경로를 나타낸 개략도.1 is a schematic diagram showing a conventional infrared sensor and the infrared sensing path.
제2도는 Si 적외선 필터의 파장과 투과율의 관계를 보인 그래프.2 is a graph showing the relationship between the wavelength and the transmittance of the Si infrared filter.
제3도는 본 발명 적외선 센서용 필터의 제조 공정도.3 is a manufacturing process chart of the filter for an infrared sensor of the present invention.
제4도는 본 발명 적외선 센서용 필터의 굴절율을 설명하기 위한 원리도.4 is a principle diagram for explaining the refractive index of the filter for an infrared sensor of the present invention.
* 도면의 주요부분에 대한 부호의 설명* Explanation of symbols for main parts of the drawings
10 : 필터 20 : 흡수층10 filter 20 absorber layer
30 : 센서 1 : Si 웨이퍼30 sensor 1 Si wafer
2 : Si3N4막2: Si 3 N 4 film
본 발명은 적외선 센서용 필터의 제조방법에 관한 것으로, 특히 소정의 두께로 연마된 Si웨이퍼 상에 Si3N4막을 성장시켜 특정영역의 파장을 투과시키는 투과율이 높은 적외선 센서용 필터의 구조 및 그 제조방법에 관한 것이다.BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an infrared sensor filter, and more particularly, to a structure of a filter having a high transmittance for transmitting a wavelength of a specific region by growing a Si 3 N 4 film on a polished Si wafer and its structure. It relates to a manufacturing method.
일반적으로 초전형 적외선 센서는 입사되는 빛을 열로 전환하여 이 열에 의한 자발분극의 변화를 측정하므로서 신호를 얻는다. 이때, 상기 빛을 열로 전환하는 역할을 하는 흡수층은 대체로 다공질 금속박막이나 기타 흡수체를 이용하여 만들어지는데 파장선택성이 없다는 단점이 지적되고 있다.In general, a pyroelectric infrared sensor converts incident light into heat and obtains a signal by measuring a change in spontaneous polarization caused by this heat. At this time, the absorption layer that serves to convert the light into heat is generally made by using a porous metal thin film or other absorber has been pointed out the disadvantage that there is no wavelength selectivity.
따라서, 특정영역의 파장선택성을 갖는 적외선 센서의 제조를 위해서는 그에 합당한 창재료로서 적외선 필터를 사용하여야 한다.Therefore, in order to manufacture an infrared sensor having wavelength selectivity in a specific region, an infrared filter should be used as a suitable window material.
종래의 인체를 감지하는 인체감지용 적외선 센서를 제1도에 도시된 적외선 센서와 적외선 감지경로를 나타낸 개략도에 의거하여 살펴보면 다음과 같다.Looking at the conventional infrared sensor for detecting a human body on the basis of the schematic diagram showing the infrared sensor and the infrared sensing path shown in FIG. 1 as follows.
Si 필터(10)와 흡수층(20) 및 센서(30)로 구성된 적외선 센서는 사람이 옷을 입고 있을 때의 표면온도가 36℃쯤 되므로 36℃의 물체에서 나오는 적외선 방사곡선에 따라서 대략 7-12㎛ 영역의 적외선을 선택적으로 측정하여야 한다.The infrared sensor composed of the Si filter 10, the absorbing layer 20, and the sensor 30 has a surface temperature of about 36 deg. Infrared radiation in the μm region should be measured selectively.
그런데, 일반적으로 사용되는 적외선 필터는 Si 재질로 이루어져 있는 바, Si의 적외선 투과곡선은 제2도에서와 같이 7-12㎛ 영역의 투과율이 50% 이하이기 때문에 이는 적외선의 감도를 떨어뜨리는 요인으로 작용한다.By the way, the commonly used infrared filter is made of Si material, and since the infrared transmission curve of Si has a transmittance of 50% or less in the 7-12 μm region as shown in FIG. Works.
상기와 같이 종래의 적외선 센서에서는, 주위환경이나 인체에서 방사되는 적외선이 일차적으로 적외선 필터(10)를 거쳐 흡수층(20)에 도달하여 열로 변환되는데, 상기 흡수층(20)은 가시광선에서 적외선의 넓은 영역의 빛에 대하여 선택성이 없이 열로 변환되기 때문에 필터(10)의 파장 선택성이 결국 파장 선택성으로 된다.In the conventional infrared sensor as described above, the infrared rays emitted from the surrounding environment or the human body first reach the absorbing layer 20 through the infrared filter 10 and is converted into heat, and the absorbing layer 20 has a wide range of infrared rays from visible light. The wavelength selectivity of the filter 10 becomes wavelength selectivity because it is converted into heat without selectivity with respect to light in the region.
그러나, 상기와 같은 종래의 적외선 센서의 필터(10)는 Si를 사용하므로 Si의 자체의 특성상 7-12㎛ 영역의 적외선만을 통과시키는 것이 아니므로 오동작을 일으키게 되는 문제점을 가지고 있으며, 그 영역에서의 투과율이 크게 변하는 문제점을 가지고 있다.However, since the filter 10 of the conventional infrared sensor as described above uses Si, it does not pass only infrared rays in the 7-12 μm region due to its own characteristics, which causes a malfunction. It has a problem that the transmittance is greatly changed.
상기와 같은 종래의 문제점을 해결하고자, 본 발명은 특정(인체)파장 영역을 투과시키는 높은 투과율을 가진 적외선 센서용 필터를 제공함에 목적을 두고 있다.In order to solve the above conventional problems, an object of the present invention is to provide a filter for an infrared sensor having a high transmittance for transmitting a specific (human body) wavelength region.
본 발명의 적외선 센서용 필터의 구조 및 그 제조방법을 첨부도면에 따라서 설명하기로 하면 다음과 같다.The structure of the infrared sensor filter of the present invention and its manufacturing method will be described with reference to the accompanying drawings.
먼저, 제3도의 제조공정도에 의거하여 본 발명 적외선 센서용 필터의 제조과정을 살펴보면, 4인치 정도의 Si웨이퍼(1)를 원하는 두께로 형성하기 위해 웨이퍼 저면(Backside)에 대한 연마(Polishing)를 행하여 그 두께가 300-520㎛정도가 되도록 연마한다. 다음 연마공정이 완료된 웨이퍼의 상면 및 저면에 PECVD(Plasma Enhance3d Chemical Vapor Deposition)법으로 Si3N4막(2)을 성장시킨다.First, referring to the manufacturing process of the infrared sensor filter of the present invention based on the manufacturing process diagram of FIG. 3, polishing of the backside of the wafer is performed to form the Si wafer 1 having a desired thickness of about 4 inches. The polishing is carried out so that the thickness thereof is about 300-520 µm. Next, a Si 3 N 4 film 2 is grown on the top and bottom surfaces of the wafer where the polishing process is completed by PECVD (Plasma Enhance 3d Chemical Vapor Deposition).
상기 Si3N4막(2)의 성장은 아래의 〈표1〉의 조건하에서 수행하되 그 두께가 주로 통과시키는 인체파장의 1/8배로 한다.The growth of the Si 3 N 4 film 2 is carried out under the conditions of <Table 1> below, but the thickness thereof is 1/8 times that of the human wavelength mainly passed.
[표 1]TABLE 1
상기와 같이 제조된 필터(10)를 빛이 투과하는 관점에서 보면, Si, Si3N4의 굴절율을 각각 n1, n2라고 했을때 제4도와 같이 표현될 수 있다.When the filter 10 manufactured as described above is transmitted from light, Si and Si 3 N 4 may be expressed as shown in FIG. 4 when the refractive indices are n 1 and n 2 , respectively.
상기 제4와 같은 구조에서 파장 λ인 빛이 수직으로 입사하면 Si층(굴절율 n1)에 이르는 빛의 세기비, 즉 투과율 T는When light having a wavelength λ is vertically incident in the fourth structure, the intensity ratio of light reaching the Si layer (refractive index n1), that is, transmittance T is
상기 식에 n1=3.48, n2=2를 대입하면 T=1 / [1+0.527 cos2(4πt)/λ]가 되어 T가 최대가 되는 가장 작은 t값은 1/8λ임을 알 수 있다.Substituting n 1 = 3.48 and n 2 = 2 in the above equation, T = 1 / [1 + 0.527 cos 2 (4πt) / λ], and it can be seen that the smallest t value at which T is the maximum is 1 / 8λ. .
그러나 인체에서 방사되는 적외선은 제2도에서와 같이 9.4㎛를 피크로 하여 7-12㎛ 정도에 주로 걸쳐 있으므로 λ=9.4㎛ 일때 가장 투과율이 좋게하기 위해서는 Si3N4층(2)의 두께 t를 1.175㎛ 정도가 되도록 하는 것이 이상적이다.However, the infrared rays emitted from the human body are mainly in the range of about 7-12 μm with a peak of 9.4 μm as shown in FIG. 2. Therefore, in order to have the best transmittance when λ = 9.4 μm, the thickness t of the Si 3 N 4 layer 2 Ideally, it should be about 1.175 mu m.
한편, 투과율을 최대로 하기 위해서는 Si3N4막(2)의 두께를 1/8λ의 홀수배로 할 수 있고 인체의 적외선 방사에너지가 7-12㎛ 영역에 비교적 넓게 분포하기 때문에 λ값도 약간의 변화를 줄 수 있으나, 모두 다 동일한 원리이다.On the other hand, in order to maximize the transmittance, the thickness of the Si 3 N 4 film 2 can be an odd multiple of 1/8 lambda, and since the infrared radiation energy of the human body is distributed relatively widely in the 7-12 μm region, the lambda value is also slightly reduced. It can change, but they are all the same principle.
이상에서 설명한 바와 같이 본 발명의 적외선 센서는 필터의 적외선 투과율이 약 90% 개선되고 파장 선택이 인체 감지에 적합하게 되므로서 특정 파장영역을 투과시키는 투과율이 높은 적외선용 필터를 제공할 수 있는 잇점이 있다.As described above, the infrared sensor of the present invention can provide an infrared filter having a high transmittance that transmits a specific wavelength range because the infrared transmittance of the filter is improved by about 90% and the wavelength selection is suitable for human detection. have.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR1019920015222A KR100275863B1 (en) | 1992-08-24 | 1992-08-24 | Structure of a filter for infrared sensor |
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| Application Number | Priority Date | Filing Date | Title |
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| KR1019920015222A KR100275863B1 (en) | 1992-08-24 | 1992-08-24 | Structure of a filter for infrared sensor |
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| Publication Number | Publication Date |
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| KR940004344A KR940004344A (en) | 1994-03-15 |
| KR100275863B1 true KR100275863B1 (en) | 2000-12-15 |
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