A self-filtering high-precision silicon quadrant photodetector and its preparation method

Abstract

The present invention provides a self-filtering high-precision silicon quadrant photoelectric detector and a preparation method thereof, comprising a tube seat with tube pins and a high-precision silicon quadrant photoelectric detector chip body arranged on the top of the tube seat, eight preamplifier circuits are arranged on the four sides of the tube seat, and a tube cap with a light window glass is sealed on the periphery of the upper circuit of the chip, and a filter film is arranged on the top surface of the light window glass, and the filter film and the light window glass together constitute the cap top of the tube cap with a self-filtering function; the preparation method steps include: pasting the high-precision silicon quadrant photoelectric detector chip body on the top of the tube seat sintered with tube pins to assemble it into one, preheating the tube cap to the target temperature, sputtering and coating the top surface of the tube cap, and sealing and welding the connection between the tube seat and the tube cap by laser or shaft wheel welding machine. The present invention realizes a significant increase in the qualified rate of self-filtering high-precision silicon quadrant photoelectric detectors, and has excellent anti-seismic performance during use.

Description

Technical Field

[0001] The invention belongs to the technical field of silicon quadrant photoelectric detectors, and in particular relates to a self-filtering high-precision silicon quadrant photoelectric detector and a preparation method thereof. Background Art

[0002] Silicon quadrant PIN photodetectors used for laser tracking and guidance are usually of two types: "single quad" and "double quad" quadrant PIN photodetectors. They are PIN photodetectors made by arranging four photodiodes with equal photosensitive areas and the same performance or eight photodiodes (divided into "inner four" - smaller photosensitive areas and "outer four" - larger photosensitive areas) according to the requirements of rectangular coordinates. The detection distance and accuracy of this type of photodetector mainly depends on the "responsivity" of the photodetector chip, the presence or absence of "photoelectric crosstalk" between quadrants, the responsiveness characteristics of the front-end amplifier components, the size of the detection blind area, and the width of the optical dynamic range.

[0003] For silicon quadrant photodetectors, the technologies developed in the early stage include the following two. One is the "Ultra-High Precision Silicon Quadrant Photodetector" disclosed in the existing document CN2020107624938, which not only increases the optical dynamic range of the chip on the basis of its original excellent performance, but also enables the system to move from "precise control" to "deep control", and obtain important applications. However, due to its extremely high responsiveness, ultra-high precision silicon quadrant photodetectors are easily interfered by background light. Sometimes during debugging on the system assembly line, interference from factory lighting can cause misjudgment or misfiring.

[0004] The second is the document CN2020107123173, which discloses “A Silicon Quadrant Photodetector with Special “Dual-All” Applications”. Although this solution completely solves the problem of background light interference and has been more widely used, it often makes it difficult to grasp the photoelectric properties of the chip itself when a filter film is evaporated on the ultra-high-precision silicon quadrant photodetector chip, causing it to deteriorate. Even if a thin glass sheet with a filter film evaporated on it is installed under the light window glass of the tube cap, the entire silicon quadrant photodetector still has the disadvantage of poor seismic performance. More importantly, when the existing solution is used to prepare a self-filtering high-precision silicon quadrant photodetector, no matter how accurately the preparation process is controlled, the product qualification rate can only be controlled below 70 percent. This technical problem has not been solved in recent years. Summary of the invention

[0005] At least in order to solve the technical problems mentioned in the background technology, the present invention aims to provide a self-filtering high-precision silicon quadrant photodetector and a preparation method thereof.

[0006] The present invention adopts the following technical solution.

[0007] A self-filtering high-precision silicon quadrant photoelectric detector comprises a tube base with tube pins and a high-precision silicon quadrant photoelectric detector chip body arranged on the top of the tube base, eight preamplifier circuits are arranged on the four sides of the tube base, and a tube cap with a light window glass is sealed (sealed and connected by laser or shaft wheel welding machine) on the periphery of the upper circuit of the chip, and a filter film is arranged on the top surface of the light window glass. The filter film and the light window glass together constitute the cap top of the tube cap with self-filtering function.

[0008] Furthermore, the filter film is a filter film obtained by sputtering titanium oxide material on the top surface of the light window glass using a sputtering process.

[0009] Furthermore, the filter film meets the requirement of 1.064 microns for the optimal wavelength of guided light waves of the silicon quadrant photodetector, and the transmittance of the central wavelength of 1.064 microns is 90%, while the suppression of other background light is (20±2)% and ≤1% respectively.

[0010] Furthermore, the short-wavelength band of the filter film is cut off at ≤0.5 micrometers, the long-wavelength band is not cut off, and the half-height and half-width are 0.064 micrometers.

[0011] A method for preparing the aforementioned self-filtering high-precision silicon quadrant photodetector, comprising the following steps:

[0012] Step 1, pasting the high-precision silicon quadrant photodetector chip body on the top of the tube holder with sintered pins to assemble them into one body, and pasting the debugged high-precision silicon quadrant photodetector preamplifier circuit around the tube holder;

[0013] Step 2: After the tube cap is preheated to the target temperature, the magnetron sputtering equipment is turned on to perform sputtering coating on the top surface of the tube cap (the film is sputtered only onto the light window glass through a metal mold to avoid sputtering onto the surrounding welded tube caps);

[0014] Step 3, after the coated tube cap cools down, the tube cap is buckled onto the tube seat, and then the connection between the tube seat and the tube cap is sealed and connected by laser or shaft wheel welding machine.

[0015] Preferably, the filter film is formed by stacking multiple sputtering coatings.

[0016] Beneficial effects: The present invention uses an extremely clever scheme to improve the qualified rate of self-filtering high-precision silicon quadrant photoelectric detectors to more than 98%, while greatly reducing the difficulty of preparation and improving processing efficiency, and the anti-seismic performance during use is very excellent; the scheme of the present invention can make the central wavelength transmittance of the self-filtering high-precision silicon quadrant photoelectric detector reach 90%, and the suppression of background light reaches two categories: (a) is when the suppression is (20±2)%, through the filter film, the "cross" alignment diagram in the center of the chip can be visually viewed - the mark for the alignment and installation of the guidance system; (b) is the suppression ≤1% (there is no need to visually view the "cross" alignment diagram in the center of the chip through the filter film, but it is positioned at the positioning hole below the standard TO25 tube socket. The chip is also positioned at the positioning hole using a video locator for installation). The scheme of the present invention can not only ensure the installation accuracy of the guidance system, but also make full use of the filtering system of the guidance system cover, so that the superposition suppression degree of the whole guidance system to the background light is as low as about 0.2% and 0.1% respectively, and the total transmittance of the central wavelength is about 80%. Under the "all-weather", "all-round" and "double-all" application conditions, it still has the high performance of "precise control" and "deep control". BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of a self-filtering high-precision silicon quadrant photodetector in an embodiment;

[0018] Figure 2 This is a schematic diagram of the main structure of a high-precision silicon quadrant photodetector chip in an embodiment;

[0019] Figure 3 A schematic diagram of a tube cap of a high-precision silicon quadrant photodetector in an embodiment;

[0020] Figure 4 Schematic diagram of the cross section of the self-filtering high-precision silicon quadrant photodetector in the embodiment;

[0021] Figure 5 The filter film characteristic transmittance curve of the self-filtering high-precision silicon quadrant photodetector in the embodiment (a is the first type of filter film, b is the second type of filter film). DETAILED DESCRIPTION

[0022] The technical solution of the present invention is described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Example

[0023] Combination Figures 1 to 5As shown, a self-filtering high-precision silicon quadrant photoelectric detector comprises a tube seat 1 and a high-precision silicon quadrant photoelectric detector chip body 2 arranged on the top of the tube seat 1 (the high-precision silicon quadrant photoelectric detector chip is a key component of the high-precision silicon quadrant photoelectric detector chip body 2), a tube pin 3 is arranged at the bottom of the tube seat 1, a tube cap 4 is arranged on the outer periphery of the upper part of the tube seat 1, and the front circuits of 8 photoelectric detectors are attached to the four walls of the tube seat in the inner cavity of the tube cap 4. The connection part between the tube seat and the tube cap is sealed and connected by laser or shaft wheel welding machine, and a light window glass 5 is arranged on the top wall of the tube cap. The thickness of the light window glass 5 is 0.9mm, and the distance between the bottom surface (inner surface) of the light window glass 5 and the upper surface of the high-precision silicon quadrant photoelectric detector chip is 0.6mm. Only a filter film is arranged on the top surface of the light window glass 5, and the filter film and the light window glass 5 together constitute the tube cap, which has a self-filtering function. Among them, the filter film is a filter film that sputters titanium oxide material on the top surface of the light window glass by sputtering process. The filter film meets the requirement of 1.064 microns as the optimal wavelength of the guided light wave of the silicon quadrant photodetector, and the transmittance of the central wavelength of 1.064 microns is 90%, which realizes long-distance detection, and the suppression degree of other background light is 20±2% and ≤1% respectively. The former is also convenient for the guidance system to visually see the "cross" alignment mark in the center of the "double four" chip during assembly; the short-wave band of the filter film is cut off at ≤0.5 microns, which is used to limit the interference of the background light in the short-wave band on the detection, and the long-wave band is not cut off (to facilitate the process of filter film manufacturing, because silicon does not absorb the background light of 1.10 microns and above at all, so it has no effect on the detector and does not need to be filtered), and the half-height and half-width are 0.064 microns. In this embodiment, the top wall of the tube cap 4 has an inwardly concave step 6, the light window glass 5 is connected to the step 6 surface by fusion sealing, the top surface of the light window glass is flush with the top wall of the tube cap, and the edge of the filter film is located inside the edge of the light window glass.

[0024] The method for preparing the self-filtering high-precision silicon quadrant photoelectric detector in this embodiment comprises the following steps:

[0025] Step 1, the high-precision silicon quadrant photodetector chip is pasted on the top of the tube holder 1, the high-precision silicon quadrant photodetector chip body 2 and the tube pin 3 are assembled into one, and the preamplifier circuit (i.e., the preamplifier detection component) of the high-precision silicon quadrant photodetector chip is debugged respectively;

[0026] Step 2, placing the tube cap in the magnetron sputtering table and positioning it;

[0027] Step 3, after preheating the tube cap 4 to the desired target temperature, start the magnetron sputtering equipment (automatic control process), perform sputtering on the top surface of the tube cap 4, and automatically stop when the filter film reaches the designed thickness, and then anneal at a constant temperature;

[0028] Step 4: After the coated tube cap 4 and the tube base 1 are positioned, they are sealed and connected by laser or shaft wheel welding machine.

[0029] In this embodiment, the self-filtering high-precision silicon quadrant photodetector refers to a high-precision silicon quadrant photodetector that has a filtering function itself (only a filter film formed by sputtering titanium oxide on the upper surface of the light window glass of the tube cap), and its characteristic curve is as follows: Figure 5 As shown in the middle curve, it is the filter film of the outer cover of the guidance system. After their filtering characteristics are superimposed, the total filtering effect is the product of the characteristic parameters of the two layers of filter films: such as the central wavelength transmittance (90% × 90%) is about 81%, and the background light suppression degree (a) category (20% ± 2%) × 1% is about 0.2%; while (b) category (≤1% × 1%) is as low as 0.1%. In this embodiment, the half-height half-width of the transmittance is 0.064 microns, which is actually the distance from the central wavelength at half the height of the transmittance (light spectrum width). The width is appropriately larger, and the angle of light incidence can be larger. It also reflects the slope of the two curves of transmittance and suppression degree. The steeper the slope, the better the suppression of background light. In this embodiment, the non-tube cap structure of the silicon quadrant photodetector and its principle refer to the existing document CN2020107624938 "A kind of ultra-high precision silicon quadrant photodetector", and this embodiment will not be repeated.

[0030] In this embodiment, the steps in the preparation method are also very critical, especially steps 3 and 4 are directly related to the qualified rate of the self-filtering high-precision silicon quadrant photodetector. The present invention uses an extremely simple and ingenious solution to increase the qualified rate of the self-filtering high-precision silicon quadrant photodetector to more than 98%, while greatly reducing the difficulty of preparation and improving the processing efficiency (the processing efficiency can be increased by about 30%), and the anti-seismic performance of the product during the application process is not affected at all.

[0031] By adopting the scheme of the present invention, the central wavelength transmittance of the self-filtering high-precision silicon quadrant photodetector can reach 90%, and the suppression degree of background light can be divided into two categories: (a) is a suppression degree of only (20±2)%, and through the filter film, the "cross" alignment pattern in the center of the chip can be visually observed - the mark for the alignment and installation of the guidance system; (b) is a suppression degree of ≤1% (there is no need to visually observe the "cross" alignment pattern in the center of the chip through the filter film, but it is positioned at the positioning hole below the standard TO25 tube seat. The chip installation is also positioned at the positioning hole using a video locator). By adopting the scheme of the present invention, the installation accuracy of the guidance system can be guaranteed, and the filtering function of the outer cover of the guidance system can be fully utilized, so that the suppression degree of the entire guidance system to the background light is as low as about 0.2% and 0.1%, and the total transmittance of the central wavelength is about 80%. Under the "all-weather" and "all-round" application conditions, it still has high performance of "precision control" and "deep control".

Claims

1. A method for preparing a self-filtering high-precision silicon quadrant photodetector, the self-filtering high-precision silicon quadrant photodetector comprising a tube base with tube pins and a high-precision silicon quadrant photodetector chip body arranged on the top of the tube base, eight preamplifier circuits are arranged on the four sides of the tube base, and a tube cap with a light window glass is sealed around the outer periphery of the upper circuit of the chip, characterized in that: Only a filter film is arranged on the top surface of the light window glass, and the filter film and the light window glass together constitute the cap top of the tube cap with self-filtering function. The filter film is a filter film made by sputtering titanium oxide material on the top surface of the light window glass by a sputtering process; The steps of the preparation method include: Step 1, stick the high-precision silicon quadrant photodetector chip on the top of the tube holder, assemble the high-precision silicon quadrant photodetector chip body and the tube pin into one, and debug the preamplifier circuit of the high-precision silicon quadrant photodetector chip respectively; Step 2, placing the tube cap in the magnetron sputtering table and positioning it; Step 3, after the tube cap is preheated to the required target temperature, the magnetron sputtering equipment is turned on to perform sputtering only on the top surface of the tube cap light window glass, and the filter film automatically stops when it reaches the designed thickness, and then annealed at a constant temperature; Step 4: After the coated tube cap and tube seat are positioned, they are sealed and connected by laser or shaft wheel welding machine.

2. The preparation method according to claim 1, characterized in that: The filter film meets the requirement of 1.064 microns for the optimal wavelength of guided light waves of the silicon quadrant photodetector, and the transmittance of the central wavelength of 1.064 microns is 90%, while the suppression degree of other background light is (20±2)% and ≤1% respectively.

3. The preparation method according to claim 1, characterized in that: The short-wave band of the filter film is cut off at ≤0.5 microns, the long-wave band is not cut off, and the half-height and half-width are 0.064 microns.

4. The preparation method according to claim 1, characterized in that: The filter film is formed by stacking multiple sputtering coatings.

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