Resistive micro-groove type detector for improving parasitic capacitance and preparation method of resistive micro-groove type detector

Abstract

The invention provides a resistive microgroove type detector for improving stray capacitance and a preparation method thereof, and the preparation method comprises the steps: S1, preparing a first composite electrode layer and a second composite electrode layer on the upper surface and the lower surface of a polyimide substrate respectively, and obtaining an amplification structure unit substrate; s2, preparing a charge discharge line based on the second composite electrode layer; s3, preparing a read-out electrode plate, and laminating the amplification structure unit base material and the read-out electrode plate; s4, manufacturing a metalized via hole outside the sensitive area; s5, the corresponding amplification structure unit base material area above the charge discharge lines is reserved to serve as a dead area, a long-strip-shaped groove array is prepared in the area outside the dead area of the amplification structure unit to serve as an amplification structure, and the remaining first composite electrode layer between grooves is processed to obtain a read-out strip; and S6, integrating a drift electrode and setting an air gap layer as a drift region, and manufacturing a peripheral circuit to complete the preparation of the resistive microgroove type detector.

Description

Technical Field

[0001] The present disclosure relates to the technical field of gas detectors, and in particular to a resistive microgroove detector with improved parasitic capacitance and a preparation method thereof. Background Art

[0002] Gas detectors play an important role in the field of large-area particle detection due to their low cost. Collision experiments are one of the most effective means of studying the fundamental properties of nuclear and particle physics. The main development directions of the new generation of colliders are high brightness and high energy, which pose great challenges to the response capability, spatial resolution and radiation resistance of traditional gas detectors. Microstructured gas detectors are a new type of gas detector developed based on PCB technology and etching technology. Compared with traditional gas ionization chambers and filament chambers, microstructured gas detectors have advantages such as fast response, high counting rate capability and high position resolution. However, current microstructured gas detectors still have problems such as high parasitic capacitance of the detector due to unreasonable structure, high noise, poor readout performance and low sensitivity. Summary of the Invention

[0003] In view of this, in order to at least partially solve at least one of the above-mentioned technical problems, the present disclosure provides a resistive micro-groove detector with improved parasitic capacitance and a preparation method thereof.

[0004] In order to achieve the above objectives, the technical solutions disclosed in this disclosure are as follows:

[0005] According to an embodiment of one aspect of the present disclosure, a method for preparing a resistive microgroove detector with improved parasitic capacitance is provided, comprising: S1: preparing a first composite electrode layer and a second composite electrode layer on the upper and lower surfaces of a polyimide substrate, respectively, to obtain an amplifying structure unit substrate; S2: preparing a charge discharge line based on the second composite electrode layer; S3: preparing a readout electrode plate and pressing the amplifying structure unit substrate and the readout electrode plate together; S4: making metallized vias outside the sensitive area; S5: retaining the amplifying structure unit substrate area corresponding to the charge discharge line above the charge discharge line as a dead zone, preparing a long strip groove array in the area outside the dead zone of the amplifying structure unit as an amplifying structure, and processing the remaining first composite electrode layer between the grooves to obtain a readout strip; and S6: integrating a drift electrode and setting an air gap layer as a drift zone, making a peripheral circuit, and completing the preparation of the resistive microgroove detector.

[0006] According to the embodiment of the present disclosure, the thickness of the polyimide substrate is d, which ranges from 50 μm≤d≤125 μm. The groove is wide at the top and narrow at the bottom, with the width of the upper groove opening ranging from d to d+20 μm and the width of the lower groove bottom ranging from 20 μm to d.

[0007] According to an embodiment of the present disclosure, the first composite electrode layer includes a Cu layer, a Cr layer, and a DLC film stacked in sequence, wherein the DLC film contacts the upper surface of the polyimide substrate, the thickness of the DLC film is between 20nm and 200nm, and the surface resistivity is between 10kΩ / □ and 20MΩ / □.

[0008] According to an embodiment of the present disclosure, the second composite electrode layer includes a Cu layer, a Cr layer, and a DLC film stacked in sequence, wherein the DLC film contacts the lower surface of the polyimide substrate, has a thickness between 20 nm and 200 nm, and a surface resistivity between 10 MΩ / □ and 200 MΩ / □. According to an embodiment of the present disclosure, operation S2 includes: etching the unprotected Cu and Cr layers of the second composite electrode layer using a photoresist film having a charge discharge line pattern for protection; and patterning the DLC film by removing the DLC film outside the sensitive area not protected by the photoresist film using a new photoresist film and a sandblasting process.

[0009] According to an embodiment of the present disclosure, in operation S3 , the amplifying structure unit substrate is pressed onto the surface of the readout electrode plate using prepreg and polyimide material, and the pressure value during pressing is 7 bar to 20 bar.

[0010] According to an embodiment of the present disclosure, after operation S4 is completed to form the metallized via hole, the Cu layer has a thickness of 20 μm to 30 μm and a width greater than 55 μm.

[0011] According to an embodiment of the present disclosure, operation S5 includes: etching the Cu layer and the Cr layer of the first composite electrode layer; removing the exposed DLC film using a sandblasting process; etching the polyimide substrate to obtain a groove array and cleaning the grooves; and micro-etching the Cu layer of the first composite electrode layer remaining between the grooves to reduce the thickness and width, and etching the Cr layer to make its width the same as that of the Cu layer to expose part of the DLC film to obtain a strip-type readout strip.

[0012] According to the embodiment of the present disclosure, when the Cu layer is micro-etched, the etching rate does not exceed 1 μm / min, so that the thickness of the Cu layer is reduced by 15 μm to 25 μm, and the width is reduced by 30 μm to 50 μm.

[0013] An embodiment of another aspect of the present disclosure provides a resistive microgroove detector prepared based on the preparation method described in any one of the above items, which includes, from top to bottom, a drift electrode, an air gap layer, an amplifying structure unit, and a bottom readout electrode unit, wherein: the air gap layer between the drift electrode and the amplifying structure unit serves as a drift region, and the drift region obtains primary electrons under the action of the particles to be measured and drifts to the amplifying structure unit; the upper side of the amplifying structure unit includes a plurality of long strip-shaped grooves serving as amplifying structures, and the lower side of the amplifying structure unit includes a plurality of charge discharge lines, and the corresponding amplifying structure unit substrate area above the charge discharge lines serves as a dead zone; the first composite electrode layer between the grooves serves as a first readout bar, and the bottom readout electrode unit includes a plurality of second readout bars, the dead zone width is greater than the first readout bar width, and the first readout bar and the second readout bar constitute a two-dimensional grid readout electrode. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The above and other objects, features and advantages of the present disclosure will become more apparent through the following description of the embodiments of the present disclosure with reference to the accompanying drawings, in which:

[0015] Figure 1 Schematic diagram of the three-dimensional resistive micro-well detector structure.

[0016] Figure 2 Schematic diagram of the structure of a resistive microgroove detector with improved parasitic capacitance according to an embodiment of the present disclosure.

[0017] Figure 3 This is a flow chart of a method for preparing a resistive microgroove detector with improved parasitic capacitance according to an embodiment of the present disclosure.

[0018] Figure 4a Schematic diagram of the process flow corresponding to operation S1 in the preparation method of a resistive microgroove detector for improving parasitic capacitance.

[0019] Figure 4b A schematic diagram of the process flow corresponding to operation S2 in the method for preparing a resistive microgroove detector for improving parasitic capacitance.

[0020] Figure 4c A schematic diagram of the process flow corresponding to operation S3 in the method for preparing a resistive microgroove detector for improving parasitic capacitance.

[0021] Figure 4d A schematic diagram of the process flow corresponding to operation S4 in the method for preparing a resistive microgroove detector for improving parasitic capacitance.

[0022] Figure 4e A schematic diagram of the process flow corresponding to operation S5 in the method for preparing a resistive microgroove detector for improving parasitic capacitance.

[0023] Figure 4fA schematic diagram of the process flow corresponding to operation S6 in the method for preparing a resistive microgroove detector for improving parasitic capacitance. DETAILED DESCRIPTION

[0024] The present disclosure provides a resistive microgroove detector and a preparation method for improving parasitic capacitance. The detector uses a long strip groove as the amplification structure of the detector, and the conductive layer on the top of the groove uses a Cu / Cr / DLC composite electrode. The Cu / Cr strip can serve as a one-dimensional readout strip, and the DLC can ensure the integrity of the multiplication electric field. This can effectively reduce the width of the readout strip and increase the distance between the two-dimensional readout electrodes without affecting the multiplication area, thereby effectively reducing the parasitic capacitance of the readout strip. It can also solve the charge sharing effect caused by the two-dimensional readout strips on the same side of the amplification structure, further improving the output signal amplitude of the detector. At the same time, the design is compatible with the charge discharge structure, which can effectively improve the counting rate capability of the detector, thereby further adapting to large-area applications.

[0025] The commonly used readout method for microstructured gas detectors is two-dimensional strip readout, with both two-dimensional readout strips located on the readout electrode PCB below the amplification structure. However, in large-area detection applications, the detector's readout strips are very long, and the two-dimensional readout strips are located very close to each other on the readout electrode PCB. This dramatically increases the parasitic capacitance of the readout strips. When connected to the readout electronics, excessive parasitic capacitance significantly reduces the detector's signal amplitude and increases crosstalk noise between channels. At the same time, the induced charge generated is shared on the two-dimensional readout strips, causing the effective signal to become smaller and difficult to distinguish from the noise. To effectively read the signal from large-area detectors, the readout electronics need to allow for a large input capacitance, but this will inevitably significantly affect other performance indicators of the electronics, thus posing a huge challenge to the design of the readout electronics. To promote the application of microstructured gas detectors in large-area track measurement and reduce the difficulty of designing their supporting electronics, it is necessary to develop an MPGD that can be manufactured on a large scale and has a low parasitic capacitance readout strip.

[0026] An existing technical solution is the resistive micro-well gas detector (μRWELL), whose three-dimensional structure is as follows Figure 1As shown. Its amplification structure is a blind hole type, with the upper layer of the blind hole being metal Cu / Cr (where Cr serves as a transition layer between the Cu layer and the Apical), the middle being an insulating medium (Apical), and the bottom being DLC. In order to achieve two-dimensional position sensitivity, a two-dimensional strip readout is often used. The readout strip is made of metal copper and is manufactured through a PCB process. This two-dimensional strip readout method has the following two major disadvantages: (1) The readout strips of both dimensions are located on the readout electrode PCB below the amplification structure. Not only do they have large parasitic capacitance, but they also share the generated charge during the signal generation process, which reduces the signal amplitude on the single-dimensional readout strip. (2) In order to ensure that the signal amplitude of the readout strip farther from the amplification structure exceeds the threshold, the width of the readout strip needs to be increased. In large-area applications, the lengthening of the wide readout strip will significantly increase the parasitic capacitance, thereby increasing the crosstalk noise and affecting the signal readout.

[0027] In order to solve the problem of excessive parasitic capacitance of the readout strip in large-area applications of the existing μRWELL solution, it is necessary to develop a microstructured gas detector with a low parasitic capacitance readout strip to increase the amplitude of the readout signal and adapt to the application of large-area track measurement.

[0028] In order to make the objectives, technical solutions and advantages of the present disclosure more clearly understood, the present disclosure is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

[0029] In the embodiment of the present disclosure, Figure 3 and Figure 4a-4f As shown, a method for preparing a resistive microgroove detector with reduced parasitic capacitance is provided, comprising:

[0030] S1: preparing a first composite electrode layer and a second composite electrode layer on the upper and lower surfaces of a polyimide substrate, respectively, to obtain an amplified structural unit substrate;

[0031] S2: preparing a charge discharge line based on the second composite electrode layer;

[0032] S3: preparing a readout electrode plate and pressing the amplification structure unit substrate and the readout electrode plate together;

[0033] S4: Make metalized vias outside the sensitive area;

[0034] S5: retaining the corresponding amplification structure unit substrate area above the charge discharge line as a dead zone, preparing a long strip groove array as an amplification structure in the area outside the dead zone of the amplification structure unit, and processing the remaining first composite electrode layer between the grooves to obtain a readout strip; and

[0035] S6: Integrate the drift electrode and set the air gap layer as the drift region, make the peripheral circuit, and complete the preparation of the resistive micro-groove detector.

[0036] According to the embodiment of the present disclosure, Figure 4a As shown, operation S1 includes:

[0037] First, if Figure 4a As shown in part (1), a polyimide substrate with a thickness of 50μm~125μm is prepared (Apical is used as an example for illustration), and one side of the surface is roughened to increase the bonding strength during the coating process.

[0038] Furthermore, if Figure 4a As shown in part (2), a Cu / Cr / DLC composite electrode, referred to as the first composite electrode, is deposited on the untreated side of the Apical using unbalanced magnetron sputtering technology. The DLC thickness in the first composite electrode ranges from 20 nm to 200 nm, with a surface resistivity of 10 kΩ / □ to 20 MΩ / □. The chromium layer serves as a transition layer, used to increase the bonding strength between the DLC and copper, and its thickness should preferably not exceed 10 nm. The copper layer is approximately (5 ± 0.2) μm thick. It should be noted that the surface resistivity of the DLC film on this side is relatively low, and its primary function is to maintain the multiplication electric field.

[0039] Furthermore, if Figure 4a As shown in part (3), a Cu / Cr / DLC composite electrode is prepared on the surface roughened on the other side of the Apical. The DLC thickness on this side is between 20nm and 200nm, and the surface resistivity is between 10MΩ / □ and 200MΩ / □. The surface resistance of the DLC film on this side is relatively higher, and its main function is to protect the amplification unit.

[0040] Furthermore, if Figure 4a As shown in part (4), the chromium layer and copper layer are continuously plated to obtain the enlarged structural unit substrate. The chromium layer is a transition layer used to increase the bonding strength between DLC and copper, and its thickness is preferably less than 10nm. The copper layer is about (5±0.2)μm thick and is an important hierarchical structure in the subsequent patterning and etching process.

[0041] According to the embodiment of the present disclosure, Figure 4b As shown, operation S2 includes:

[0042] First, if Figure 4bAs shown in part (1), the Cu and Cr layers of the unprotected second composite electrode layer are etched by using a photoresist film with a charge discharge line pattern for protection. Specifically, according to the size of the detector to be processed, a polyimide substrate coated with a resistive DLC film of appropriate size is cut, and positioning holes are processed on the substrate. A photoresist film is applied to the surface of the Cu layer of the second composite electrode layer on the side of the amplifying structure unit substrate coated with a DLC film with a surface resistivity of 10-200MΩ / □, and the film is exposed and developed according to the positioning holes to produce a long strip charge discharge line pattern with a width of 50μm~150μm. Then, the developed photoresist film is used as a mask to etch the Cu and Cr layers to expose the DLC film. The photoresist film is then removed, and the amplifying structure unit substrate is cleaned and dried.

[0043] Furthermore, if Figure 4b As shown in part (2), the DLC film outside the sensitive area that is not protected by the photoresist is removed by sandblasting to achieve patterning of the DLC film. Specifically, a new photoresist is applied to the side where Cu and Cr are etched and exposed and developed according to the positioning holes, so that the DLC in the sensitive area of the detector is protected by the photoresist, while the DLC outside the sensitive area is completely exposed. Sandblasting is then performed. The purpose is to remove the DLC outside the sensitive area of the detector. After sandblasting is completed, the photoresist is removed, cleaned, and dried.

[0044] According to the embodiment of the present disclosure, Figure 4c As shown, operation S3 includes:

[0045] First, if Figure 4c As shown in part (1), the detector readout electrode plate is prepared by a standard PCB process and positioning holes are opened. The readout structure is a one-dimensional readout strip.

[0046] Furthermore, if Figure 4c As shown in part (2), vacuum lamination technology is used to press the DLC-coated amplifying structure unit substrate onto the readout electrode plate using Pre-preg film (Pre-impregnated, prepreg) and a polyimide film (such as Kapton) with a thickness of (12±0.5) μm. The pressure used for pressing is 7 bar ~20 bar. The structure after pressing from bottom to top is the readout electrode plate PCB, Pre-preg film, Kapton, Pre-preg film, amplifying structure unit substrate, where the side of the polyimide substrate that has not been etched with Cu and Cr is at the top.

[0047] According to the embodiment of the present disclosure, Figure 4d As shown, operation S4 includes:

[0048] Holes are drilled in areas outside the sensitive region without DLC and then metalized via electroplating. This allows the fabrication of readout circuitry on the copper layer, which can then interconnect with circuitry on the readout electrode PCB for signal readout. Metallization is completed through copper deposition and electroplating, increasing the thickness of the copper layer on the polyimide substrate to 20μm to 30μm.

[0049] According to the embodiment of the present disclosure, Figure 4e As shown, operation S5 includes:

[0050] First, if Figure 4e As shown in part (1), the corresponding amplifying structure unit substrate area above the charge discharge line is retained as a dead zone, and a photoresist film is applied to the surface of the amplifying structure unit substrate of the composite PCB board and exposed and developed to produce a mask pattern for etching the amplifying structure. Then, Cu and Cr are etched using the developed photoresist film as a mask. The width of the long strip groove etched on the Cu / Cr layer is d~(d+20μm), where d is the thickness of the polyimide used, which ranges from 50μm to 125μm; the center spacing of the groove-type amplifying structure depends on the specific application, but the width of the copper strips between adjacent groove-type amplifying structures is greater than 55μm. After etching is completed, the photoresist film used for etching needs to be retained.

[0051] Furthermore, if Figure 4e As shown in part (2), since DLC does not react to the copper-chromium etching solution, sandblasting is used to physically destroy its layered structure. The sandblasted area is the area where the DLC is exposed after etching the Cu and Cr layers.

[0052] Furthermore, if Figure 4e As shown in part (3), the remaining copper-chromium layer is used as a mask to etch the polyimide substrate, obtaining an array of long strip grooves, which serve as the amplification structure. Since the DLC layer is damaged by sandblasting, it can ensure that the etching solution contacts and reacts with the polyimide substrate.

[0053] Furthermore, if Figure 4e As shown in part (4), high pressure gas is used to clean the DLC layer residue left after etching. The clean groove enlarged structure obtained after removing the DLC residue is as follows Figure 4e As shown in part (5) in the figure, since the amplifying structure is in the shape of a long groove, the remaining metal layer at the top of the groove is also in the shape of a long strip and can be grounded to be used as a one-dimensional readout strip.

[0054] Furthermore, if Figure 4eAs shown in part (6), a photoresist film is applied to the upper and lower surfaces of the composite PCB and exposed and developed, so that only the sensitive area of the detector on the upper surface of the composite PCB is exposed, and the other areas are protected by the photoresist film. Then, Cu is micro-etched, and the etching speed does not exceed 1μm / min. The etching time is adjusted according to the etching speed. The thickness of the copper layer is reduced by about 15μm~25μm, and the width of the copper strip is reduced by about 30μm~50μm. After the micro-etching of copper is completed, Cr is etched. The purpose of this step is to reduce the width of the metal readout strip, which can reduce the readout capacitance of the readout strip in this dimension. At the same time, since DLC does not react to copper and chromium etching liquids, the DLC layer will be completely retained to ensure the integrity of the multiplied electric field. In this way, it is possible to maintain the complete amplification structure while significantly reducing the parasitic capacitance of the readout strip.

[0055] According to the embodiment of the present disclosure, Figure 4f As shown, operation S6 includes:

[0056] Peripheral circuits are fabricated on the Cu / Cr layer of the polyimide substrate and the Cu layer on the bottom surface of the readout electrode board PCB. The board's outer shape is then processed to obtain a composite PCB structure combining the amplification structure unit and the bottom readout electrode unit. This step primarily involves fabricating circuits for high-voltage supply, charge discharge, and signal output on the polyimide substrate surface and the readout electrode board PCB. The overall shape of the composite PCB structure of the amplification structure unit and the bottom readout electrode unit is then processed according to the detector design. Drift electrodes are then integrated and an air gap layer is provided as a drift region, ultimately completing the preparation of a resistive microgroove detector with improved parasitic capacitance.

[0057] Example 1: Combination Figure 3 and Figure 4a-4f As shown in the figure, a resistive micro-groove detector with improved parasitic capacitance and an effective area of 10cm×10cm is used as an example to illustrate the preparation method of the detector proposed in the present invention: First, a polyimide (Apical) substrate with a thickness of 50μm and a length and width of 30cm is cut and pasted on a standard copper substrate. The exposed side of the polyimide substrate is treated using the surface roughening process used in PCB processing to increase the surface roughness of the polyimide substrate. Furthermore, the sandblasted polyimide substrate is clamped on a rotating rack in the chamber of a magnetron sputtering coating device; the vacuum degree of the chamber is controlled to 5×10 -5 The power on the graphite target is 2-5kW, preferably 4kW; the sputtering time is 20-40min, preferably 35min, and the resistivity of the resulting resistive electrode is about 60-70MΩ / □. Protect the side of the substrate coated with DLC, and coat the other side of the polyimide substrate with DLC of lower surface resistance. Control the vacuum degree to 5×10 -5The coating time is 50-55 minutes, and the surface resistivity of the obtained DLC is about 15-20MΩ / □. Then, a Cr-Cu metal layer is deposited on both sides of the DLC resistive electrode. The Cr layer acts as an intermediate layer to enhance the bonding strength between DLC and Cu. Cr and Cu are prepared in one furnace, and the vacuum degree is controlled at 5×10 -4The Cr target power was 3 kW for 1 minute, resulting in a thickness of approximately 10 nm. The Cr target power was reduced to 0 kW within 30 seconds, while the Cu target power was simultaneously increased from 0 kW to 1 kW and maintained for 8 hours, resulting in a Cu layer with a thickness of approximately 5 μm. Due to the influence of the chamber temperature during copper plating, the surface resistivity of the DLC electrode decreased by approximately 30%. As a result, the resistivity of the DLC used as a protective electrode ultimately reached approximately 42–49 MΩ / □, while the DLC used to maintain the multiplication field maintained a resistance of approximately 10–14 MΩ / □. Furthermore, positioning holes were fabricated on the Apical substrate. A photoresist film was applied to the Cu surface on one side of the DLC film with a surface resistivity of 42–49 MΩ / □. Exposure and development were performed along the positioning holes to produce a fast grounding strip pattern with a width of 50–150 μm, preferably 100 μm. The developed photoresist film was then used as a mask to etch the Cu / Cr layer, thereby forming the charge discharge line. The period length of the charge discharge line needs to be determined according to the detector's counting rate requirements, and is 51.2mm here. Furthermore, after the charge discharge line etching is completed, the photoresist film on the Apical substrate is stripped, cleaned, and dried. A photoresist film is then applied to the exposed DLC side and exposed and developed according to the positioning holes, protecting the 13cm×13cm DLC as the sensitive area. The DLC outside the sensitive area is exposed. This 13cm×13cm sensitive area includes not only the 10cm×10cm effective working area of the detector, but also the additional process area required to process this 10cm×10cm effective area. The DLC outside the sensitive area not protected by the photoresist film is then removed by sandblasting. After the sandblasting is completed, the photoresist film is removed by a stripping process, and finally the film is cleaned and dried to obtain a substrate for subsequent lamination and etching. Furthermore, the detector readout electrode plate is fabricated using standard PCB processing. The readout structure consists of a one-dimensional readout strip, referred to as the second readout strip, with a period of 400μm, a readout strip width of 80μm, and a strip thickness of 5-15μm, preferably 5μm. The thickness of the second readout strip influences the thickness of the subsequent prepreg film (Pre-Preg). A 25-50μm thick Pre-Preg is used to press a 12.5-50μm thick polyimide film (kapton) onto the PCB surface. The optimal value for the Pre-Preg thickness is 25μm, and the preferred value for the kapton thickness is 12.5μm. The pressure range is 7-20bar, with a preferred value of 10bar. Specifically, for example, pure glue type Pre-preg with a thickness of 25 μm and Kapton with a thickness of 12.5 μm are selected, and the polyimide substrate with DLC pattern treatment is pressed onto the readout electrode plate with a pressure of 10 bar to obtain a composite PCB board, in which the side of the polyimide film that has not been etched with Cu and Cr is at the top.Furthermore, mechanical drilling is used to drill holes outside the sensitive area, and the hole walls are metallized through the standard PCB electroplating copper deposition process. These metallized vias will be used for electrical connections, including the connection between the readout bar and the readout connector. During the electroplating process, copper will also be deposited on the surface of the substrate, so that the original copper layer is thickened to 20μm-30μm, which helps the stability of the copper layer in the subsequent etching process and prevents it from being completely etched. In this specific embodiment, the thickness of the copper layer is 30μm after the metallization is completed. Furthermore, a photoresist film is attached to the surface of the substrate of the amplifying structure unit of the composite PCB board and exposed and developed to produce a mask pattern for etching the amplifying structure and for covering the dead zone required for the charge discharge line. The period of the amplified area is 200μm, the width of the Cu / Cr etched in one period is 70μm, and the width of the remaining Cu / Cr is 130μm. During the patterning process, the area corresponding to the charge discharge line needs to be reserved as a dead zone to avoid the preparation of the amplified structure. The dead zone width is 400μm, and the period length is the same as the period length of the charge discharge line, which is 51.2mm. After that, the Cu layer and the Cr layer are etched using the developed photoresist film as a mask. Furthermore, the DLC area exposed after the Cu / Cr layer is etched is sandblasted to destroy its physical structure and expose the polyimide substrate. Furthermore, the polyimide substrate is etched. Since polyimide has the characteristics of anisotropic etching, the cross-section of the etched groove structure is an inverted trapezoidal structure with a width at the top and a narrowness at the bottom. The upper groove width is 70 μm obtained by graphical preparation, and the lower groove bottom width is determined according to the etching time of the polyimide substrate. The minimum width is 20 μm, and the maximum width is the same as the thickness of the polyimide substrate, preferably 50 μm. Furthermore, after the polyimide etching is completed, high-pressure gas is used to clean the remaining DLC residue to obtain a clean groove-type amplification structure. Furthermore, a photoresist film is attached to the upper and lower surfaces of the composite PCB and exposed and developed, so that only the sensitive area of the detector on the upper surface of the composite PCB is exposed, and other areas are protected by the photoresist film. Within one amplification structure cycle, the metal strip at the top of the slot initially has a width of 130 μm and a thickness of 30 μm. Cu is micro-etched at an etching rate of approximately 1 μm / min. After 25 minutes of etching, the copper layer thickness decreases by approximately 25 μm, and the copper strip width decreases by approximately 50 μm, for a final strip width of approximately 80 μm. After Cu etching is complete, Cr is etched using copper as a mask. Furthermore, connecting circuits are fabricated using standard PCB processes and connected to peripheral circuits through previously completed metallized vias. Finally, the detector's outer shape is machined using a milling machine, followed by integration of drift electrodes and the provision of an air gap layer as a drift region, completing the fabrication of a resistive micro-groove detector with a charge discharge structure.Testing of the resistive microgroove detector made of the above-mentioned sized materials shows that its parasitic capacitance can be reduced by about 26% compared to a resistive microgroove detector of the same size without reducing the readout strip width, and can be reduced by about 57% compared to a μRWELL detector of the same size.

[0058] Another aspect of the present disclosure is an embodiment of Figure 2 and Figure 4a-4f As shown, a resistive microgroove detector prepared based on the above preparation method is also provided, which includes a drift electrode, an air gap layer, an amplification structure unit, and a bottom readout electrode unit from top to bottom, wherein:

[0059] An air gap of several millimeters between the drift electrode and the amplifying structure unit serves as a drift region. The drift region receives primary electrons under the action of the particles to be measured and drifts to the amplifying structure unit.

[0060] The upper side of the amplifying structure unit includes a plurality of long strip-shaped grooves serving as the amplifying structure, and the lower side of the amplifying structure unit includes a plurality of charge discharge lines. The corresponding amplifying structure unit substrate area above the charge discharge lines serves as a dead zone; the first composite electrode layer between the grooves serves as a first readout strip, and the bottom readout electrode unit includes a plurality of second readout strips. The dead zone width is greater than the width of the first readout strip, and the first readout strip and the second readout strip constitute a two-dimensional grid readout electrode.

[0061] The disclosed resistive microgroove detector for improving parasitic capacitance has an amplifying structure in the shape of a long groove, with a full-surface DLC resistive electrode at the bottom for quenching the detector's spark discharge, an intermediate insulating medium of a polyimide material (Apical), and a top conductive layer of a Cu / Cr / DLC composite electrode, wherein the Cu / Cr is in the shape of a long strip and can be used as a one-dimensional readout bar; the other-dimensional readout bar is located on the readout electrode PCB and is manufactured using a standard PCB process. Since the two-dimensional readout bars are located on both sides of the amplifying structure, the charge sharing effect can be avoided, thereby increasing the signal amplitude on the one-dimensional readout bar. At the same time, since the DLC electrode is transparent to the sensing signal, the top composite electrode can be processed into a stepped shape with a wide DLC and a narrow Cu / Cr. This can maintain the integrity of the multiplied electric field in the groove-shaped amplifying region through the DLC, and can also reduce the width of the Cu / Cr strip to limit the matching capacitance of the readout bar. A detector with this structure can effectively reduce the parasitic capacitance on the two-dimensional readout bars while ensuring that the signal amplitude is large enough.

[0062] This disclosure proposes a resistive microgroove detector with improved parasitic capacitance and a fabrication method. This method not only effectively produces a detector with large signal amplitude and low parasitic capacitance, but also effectively avoids charge sharing effects, significantly increasing signal amplitude. This not only effectively improves the performance of the detector itself but also significantly reduces the requirements for its supporting electronics. This invention significantly promotes the application of MPGD using two-dimensional strip-shaped readout electrodes in large-area track measurement.

[0063] The embodiments of the present disclosure have been described in detail with reference to the accompanying drawings. It should be noted that any implementations not depicted or described in the drawings or the main text of the specification are known to those skilled in the art and are not described in detail. Furthermore, the above definitions of the various elements and methods are not limited to the various specific structures, shapes, or methods described in the embodiments, and can be easily modified or replaced by those skilled in the art.

[0064] Furthermore, unless otherwise specified, ordinal numbers such as "first" and "second" are used herein solely to distinguish multiple components with the same name and do not imply a hierarchy, level, execution order, or process sequence between them. A "first" component and a "second" component may appear together in the same component or in different components. The presence of a component with a higher ordinal number does not necessarily imply the presence of the other component with a lower ordinal number.

[0065] In this document, unless otherwise specified, the so-called feature A "or" or "and / or" feature B means that A exists alone, B exists alone, or A and B exist at the same time; the so-called feature A "and" or "and" or "and" feature B means that A and B exist at the same time; the so-called "include", "comprise", "have" and "contain" mean including but not limited to these.

[0066] Furthermore, in this document, terms such as "upper," "lower," "left," "right," "front," "back," or "between" are used solely to describe the relative positions of multiple elements and can be interpreted to include translation, rotation, or mirroring. Furthermore, in this document, unless otherwise specified, "an element is on another element" or similar descriptions do not necessarily mean that the element contacts the other element.

[0067] Furthermore, unless specifically described or required to occur sequentially, the order of the steps is not limited to the order listed above and may be varied or rearranged based on desired design requirements. Furthermore, the above embodiments may be mixed and matched with each other or with other embodiments based on design and reliability considerations. That is, the technical features of different embodiments may be freely combined to form more embodiments.

[0068] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present disclosure. It should be understood that the above are only specific embodiments of the present disclosure and are not intended to limit the present disclosure. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present disclosure should be included in the scope of protection of the present disclosure.

Claims

1. A method for preparing a resistive microgroove detector for improving parasitic capacitance, comprising: S1: preparing a first composite electrode layer and a second composite electrode layer on the upper and lower surfaces of a polyimide substrate, respectively, to obtain an amplified structural unit substrate; S2: preparing a charge discharge line based on the second composite electrode layer; S3: preparing a readout electrode plate and pressing the amplification structure unit substrate and the readout electrode plate together; S4: Make metalized vias outside the sensitive area; S5: retaining the corresponding amplification structure unit substrate area above the charge discharge line as a dead zone, preparing a long strip groove array as an amplification structure in the area outside the dead zone of the amplification structure unit, and processing the remaining first composite electrode layer between the grooves to obtain a readout strip; and S6: Integrate the drift electrode and set the air gap layer as the drift region, make the peripheral circuit, and complete the preparation of the resistive micro-groove detector.

2. The preparation method according to claim 1, wherein the thickness of the polyimide substrate is d, which is in the range of 50 μm≤d≤125 μm, the groove is wide at the top and narrow at the bottom, the width of the upper notch is between d and d+20 μm, and the width of the lower groove bottom is between 20 μm and d.

3. The preparation method according to claim 1, wherein the first composite electrode layer comprises a Cu layer, a Cr layer, and a DLC film stacked in sequence, wherein the DLC film contacts the upper surface of the polyimide substrate, the DLC film has a thickness between 20 nm and 200 nm, and a surface resistivity between 10 kΩ / □ and 20 MΩ / □.

4. The preparation method according to claim 1, wherein the second composite electrode layer comprises a Cu layer, a Cr layer, and a DLC film stacked in sequence, wherein the DLC film contacts the lower surface of the polyimide substrate, and the DLC film has a thickness between 20 nm and 200 nm and a surface resistivity between 10 MΩ / □ and 200 MΩ / □.

5. The preparation method according to claim 4, wherein operation S2 comprises: The unprotected Cu layer and Cr layer of the second composite electrode layer are etched by using a photoresist film having a charge discharge line pattern for protection; as well as The DLC film is patterned by removing the DLC film outside the sensitive area not protected by the photoresist film based on the new photoresist film using a sandblasting process.

6. The preparation method according to claim 1, wherein in operation S3, the amplifying structure unit substrate is pressed onto the surface of the readout electrode plate using prepreg and polyimide material, and the pressure value during pressing is 7 bar to 20 bar. 7 . The preparation method according to claim 3 , wherein after the metallized via hole is formed in operation S4 , the Cu layer has a thickness of 20 μm to 30 μm and a width greater than 55 μm.

8. The preparation method according to claim 7, wherein operation S5 comprises: Etching the Cu layer and the Cr layer of the first composite electrode layer; The exposed DLC film is removed using a sandblasting process; etching a polyimide substrate to obtain a groove array and cleaning the grooves; The Cu layer of the remaining first composite electrode layer between the grooves is micro-etched to reduce the thickness and width, and the Cr layer is etched to make its width the same as that of the Cu layer to expose part of the DLC film to obtain a stripe-type readout strip. 9 . The preparation method according to claim 8 , wherein when the Cu layer is micro-etched, the etching rate does not exceed 1 μm / min, so that the thickness of the Cu layer is reduced by 15 μm to 25 μm, and the width is reduced by 30 μm to 50 μm.

10. A resistive microgroove detector prepared by the preparation method according to any one of claims 1 to 9, comprising, from top to bottom, a drift electrode, an air gap layer, an amplifying structure unit, and a bottom readout electrode unit, wherein: The air gap layer between the drift electrode and the amplifying structure unit serves as a drift region. The drift region obtains primary electrons under the action of the particles to be measured and drifts to the amplifying structure unit. The upper side of the amplifying structure unit includes a plurality of long strip-shaped grooves serving as the amplifying structure, and the lower side of the amplifying structure unit includes a plurality of charge discharge lines. The corresponding amplifying structure unit substrate area above the charge discharge lines serves as a dead zone; the first composite electrode layer between the grooves serves as a first readout strip, and the bottom readout electrode unit includes a plurality of second readout strips. The dead zone width is greater than the width of the first readout strip, and the first readout strip and the second readout strip constitute a two-dimensional grid readout electrode.

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