CN103855251A

CN103855251A - Manufacturing method of monolithic integration type infrared micro lens line

Info

Publication number: CN103855251A
Application number: CN201410020943.0A
Authority: CN
Inventors: 徐鹏霄; 乔辉; 张可锋; 李向阳; 王仍; 刘诗嘉; 徐斌; 刘秀娟; 卢怡丹; 王立伟; 常超
Original assignee: Shanghai Institute of Technical Physics of CAS
Current assignee: Shanghai Institute of Technical Physics of CAS
Priority date: 2014-01-17
Filing date: 2014-01-17
Publication date: 2014-06-11

Abstract

The invention discloses a method for preparing a single-chip integrated infrared microlens line array. The method adopts the method of photolithography overlay combined with ICP dry etching, and then adopts chemical wet etching to prepare microlenses with uniform curvature radii. Lens array. This method provides a basis for optimizing the light-gathering ability of a single-chip integrated infrared microlens array, and is of great significance for improving device performance and optimizing device design.

Description

A kind of preparation method of monolithic integrated infrared lenticule alignment

Technical field

The present invention relates to infrared alignment detector, specifically refer to prepare the method for the integrated refractive lenticule of the monolithic alignment with light gathering on the substrate CdZnTe of cadmium-telluride-mercury infrared detector material.

Background technology

Along with the development of the progress of infrared technique and the application of space remote sensing, ternary system compound semiconductor materials HgCdTe is because its energy gap is adjustable continuously with component, response range covers whole infrared band and (comprises 1～3 μ m, 3～5 μ m and tri-atmospheric windows of 8～14 μ m), become the preferred material of developing unit, multielement infrared detector and infrared focus plane.

Detector array pixel is in improving pixel responsiveness, also increased the light cross-talk between adjacent picture elements in array, because the defect concentration of HgCdTe material is higher, pixel dimension is larger in addition, the dark current of each pixel is also corresponding higher, certainly will cause the decline of device detectivity.In order to address this problem, someone has proposed backing material to be designed to lenticular idea (Antoni Rogalski, Infrared detectors:status and trends[J], Progress in Quantum Electronics, 2003,27:59-210), by lenticular optically focused effect, incident light is converged to photosensitive first district, reduce the physical area of device, make by this method device in the case of photoresponse rate constant even increase significantly reduce the light cross-talk between electric current and the adjacent picture elements of device.

The lenticular method of current reported making has a lot, comprises melting photoresist method, mold replica method, laser straight literary style, mobile mask method etc., also mainly two kinds of point refractive and diffraction types of the lenticule of preparing.But due to HgCdTe Infrared Detectors and the non-refractory of substrate CdZnTe material and frangible particularity, said method is all difficult for making and realizing on CdZnTe substrate, the present invention sets about development from refractive lenticule alignment direction, the method that has proposed a set of based semiconductor making technology realizes prepares lenticule alignment on CdZnTe substrate, and the lenticule alignment of this monolithic integrated form is significant for the light cross-talk between pixel in raising device detectivity and reduction alignment.

Summary of the invention

The invention provides a kind of manufacture method of preparing monolithic integrated infrared lenticule alignment on CdZnTe substrate, directly on cadmiumzinctellutidesubstratematerial, prepare refractive optics lenticule incident infrared light is converged to detector photosurface, in the light cross-talk reducing between adjacent picture elements, reduce the physical area of actual fabricate devices, and then reduced dark current, greatly improved the performance of device.This method, for the light gathering of optimizing the integrated infrared micro lens array of monolithic provides foundation, all has great significance for improving the designs of device performance and optimised devices.

The method is in conjunction with the technology of photoetching in semiconductor technology and ICP etching, after each photoetching, carry out ICP etching, front and back are carried out four mask alignment altogether, complete the step that produces 16 equal altitudes after four etchings, finally adopt chemical wet etching to generate the consistent lenticule sphere of radius of curvature.Wherein, lenticule alignment be on the substrate of detector chip directly preparation produce, each photosensitive unit in vertical corresponding photosensitive first alignment one by one respectively, and the photosensitive first centre normal coincidence corresponding with it of each lenticular optical axis.

Its step is as follows:

Step 1: lithography mask version design and fabrication, according to the result of optical simulation, determine the size and dimension of infrared lenticule alignment, and then size and the shape of alignment figure when clearly every step photoetching process, on mask plate and the jewel sheet with reading circuit, leave the photo-etching mark that can aim at for lithography alignment.

Step 2: substrate preliminary treatment, the detector chip wax that is connected with circuit jewel sheet that preparation is completed is attached on abrasive disc glass plate, CdZnTe substrate in the above, with the jewel sheet of circuit below, use again vacuum silicon chip machine by it pressing (ensureing that thickness difference is within the scope of 3 μ m), CdZnTe substrate is made to rough polishing reduction processing, remake essence throwing attenuate and go damage to process, take off detector chip and clean post-drying.

Step 3: the photoetching of lenticule deep mesa and etching, thick, essence are thrown to detector chip after treatment and carry out photoetching, because be connected on the jewel sheet of detector chip and leave photo-etching mark before, when photoetching, aim at by the photo-etching mark on this mark and mask plate, realizing the lenticule alignment that subsequent technique prepares aims at one by one with the centre normal of the detector line array of chip front side, also photo-etching mark is copied on clean CdZnTe substrate, facilitate subsequent optical carving technology simultaneously.Then carry out first step lenticule deep mesa etching, after the floating glue of ICP etching, form the CdZnTe table top of high-aspect-ratio.

Step 4: four photoetching of step lenticule and etchings, the dash area of lithography mask version is designed to two parts for the second time, and after photoetching, covering protection etches the part of following table for the first time with photoresist respectively.ICP etching depth also only has the half of etching depth for the first time, after the floating glue of ICP etching, forms the lenticule table top with four steps.

Step 5: eight photoetching of step lenticule and etchings, the dash area of lithography mask version is designed to four parts for the third time, a part for four table tops that after photoetching, covering protection etches for the second time with photoresist respectively.ICP etching depth is the half of etching depth for the second time, after the floating glue of ICP etching, forms the lenticule table top with eight steps.

Step 6: 16 photoetching of step lenticule and etchings, the dash area of four mask mask plate is designed to eight parts, a part for eight table tops that after photoetching, covering protection etches for the third time with photoresist respectively.ICP etching depth is the half of etching depth for the third time, after the floating glue of ICP etching, forms the lenticule table top with 16 steps.

Step 7: chemical corrosion moulding, by after the lenticule table top cleaning, drying with 16 steps etching, adopt bromo-ethanol chemical wet etching, erode corner angle vertical on step, form surface-brightening, damage little, the uniform lenticule sphere of radius of curvature.

The invention has the advantages that: first drawn the optical parametric of refractive lenticule convergence incident light by optical simulation, comprised focal length, radius of curvature, spherical crown height etc.; On tellurium zinc cadmium substrate, directly prepare lenticule alignment, integrated level is high, has reduced the loss of incident light in route of transmission; Utilize the method to prepare lenticule alignment, processing step is simple and easy to realize, and it is high to prepare lenticule surface smoothness; Utilize the converging action of lenticule alignment to incident infrared light, greatly reduced the light cross-talk between dark current and the adjacent picture elements of device, there is important practical significance to improving device performance.

Brief description of the drawings

Fig. 1 is the schematic flow sheet that this patent is prepared lenticule alignment.

Embodiment

Below, in conjunction with Figure of description, the preparation method's of a kind of monolithic integrated infrared of this patent lenticule alignment concrete step of preparation process is described in detail:

Step 1: lithography mask version design and fabrication, according to the result of optical simulation, these infrared lenticule crown height 130 μ m, sphere curvature radius 200 μ m, and then size and the shape of alignment figure when clearly every step photoetching process, on mask plate and the jewel sheet with reading circuit, leave the photo-etching mark that can aim at for lithography alignment.

The preliminary treatment of step 2:CdZnTe substrate, the detector chip wax that is connected with circuit jewel sheet that preparation is completed is attached on abrasive disc glass plate, CdZnTe substrate in the above, with the jewel sheet of circuit below, use again vacuum silicon chip machine by it pressing (ensureing that thickness difference is within the scope of 3 μ m), CdZnTe substrate is made to rough polishing reduction processing, remake essence throwing attenuate and go damage to process, take off chip.

Step 3: substrate cleans, puts into respectively chloroform, ether, acetone, ethanol by substrate chip and drags and wash with cotton, and every step is cleaned 1 minute, uses N after cleaning ₂dry up.

Step 4: spin coating four bed thickness glue on CdZnTe substrate, 4000 revs/min of glue spreader rotating speeds, carry out photoetching for the first time, make mask pattern by lithography, clean 3 minutes after the good figure of photoetching with oxygen plasma.

Step 5: adopt CH ₄/ N ₂the inductively coupled plasma of/Ar γ-ray emission carries out deep mesa ICP etching, and etch period 3.5 hours, floats glue processing after completing, prepare CdZnTe table top.

Step 6: spin coating double thickness glue on the CdZnTe table top preparing, 3000 revs/min of glue spreader rotating speeds, carry out photoetching for the second time, make mask pattern by lithography, clean 3 minutes after the good figure of photoetching with oxygen plasma.

Step 7: adopt CH ₄/ N ₂the inductively coupled plasma of/Ar γ-ray emission carries out ICP etching, and etch period 100 minutes, floats glue processing after completing, and prepares the CdZnTe table top with four steps.

Step 8: spin coating single monolayer thick glue on the four step CdZnTe table tops that complete, 3000 revs/min of glue spreader rotating speeds, carry out photoetching for the third time, make mask pattern by lithography, clean 3 minutes after the good figure of photoetching with oxygen plasma.

Step 9: adopt CH ₄/ N ₂the inductively coupled plasma of/Ar γ-ray emission carries out ICP etching, and etch period 50 minutes, floats glue processing after completing, and prepares the CdZnTe table top with eight steps.

Step 10: spin coating single monolayer thick glue on the eight step CdZnTe table tops that prepare, 4000 revs/min of glue spreader rotating speeds, carry out four mask, make mask pattern by lithography, clean 3 minutes after the good figure of photoetching with oxygen plasma.

Step 11: adopt CH ₄/ N ₂the inductively coupled plasma of/Ar γ-ray emission carries out ICP etching, and etch period 30 minutes, floats glue processing after completing, and prepares the CdZnTe table top with 16 steps.

Step 12: 16 step CdZnTe table tops clean, puts into respectively chloroform, ether, acetone, ethanol by substrate chip and drags and wash with cotton, and every step is cleaned 1 minute, uses N after cleaning ₂dry up, dry.

Step 13: chemical wet etching moulding, to under the bromo-ethanolic solution room temperature condition of the lenticule table top employing 5% with 16 steps etching, carry out chemical wet etching, etching time 8 minutes, erode corner angle vertical on each step, form surface-brightening, damage little, the uniform lenticule sphere of radius of curvature.

Step 14:CdZnTe lenticule cleans, and the lenticule alignment preparing is put into respectively to chloroform, ether, acetone, ethanol and drag and wash with cotton, and every step is cleaned 1 minute, uses N after cleaning ₂dry up, dry, complete the preparation of monolithic integrated infrared lenticule alignment.

Claims

1. A method for preparing a monolithic integrated infrared microlens array, characterized in that it may further comprise the steps:

Step 1: Design and manufacture of lithography mask. According to the results of optical simulation, determine the size and shape of the infrared microlens line array, and then determine the size and shape of the overlay graphics in each step of the lithography process. Four photolithography The mask pattern used in the process is a layer-by-layer overlay pattern designed according to the size of the microlens. The size of the pattern is slightly larger than the size of the corresponding position on the spherical surface of the target microlens by 1 to 5 μm. Alignable lithographic marks for lithographic alignment;

Step 2: Substrate pretreatment, the prepared detector chip connected with the circuit gemstone is pasted on the ground glass plate with wax, the CdZnTe substrate is on the top, the gemstone with the circuit is on the bottom, and then vacuum silicon Flatten it with a chip machine to ensure that the thickness difference is within 3 μm. The CdZnTe substrate is subjected to rough polishing and thinning treatment, and then fine polishing and thinning to remove damage. The detector chip is removed for cleaning and drying;

Step 3: Photolithography and etching of the deep mesa of the microlens, and photolithography of the detector chip after rough and fine polishing, because there is a photolithography mark on the gemstone chip connected to the detector chip before, and the photolithography passes through the mark Align with the lithography mark on the mask plate to realize the one-to-one alignment between the microlens line array prepared by the subsequent process and the center normal of the detector line array on the front of the chip, and also copy the lithography mark to the clean CdZnTe On the substrate, it is convenient for the subsequent photolithography process; then perform the first step of microlens deep mesa etching, and form a high aspect ratio CdZnTe mesa after ICP etching the relief;

Step 4: Photolithography and etching of four-step microlenses. The shadow part of the second photolithography mask is designed as two parts. After photolithography, they are respectively covered with photoresist to protect a part of the upper and lower mesa etched for the first time; The ICP etching depth is only half of the first etching depth. After ICP etching the relief, a microlens mesa with four steps is formed;

Step 5: Eight-step microlens photolithography and etching, the shadow part of the third photolithography mask is designed into four parts, and after photolithography, cover and protect the four mesas etched in the second time with photoresist respectively One part; the ICP etching depth is half of the second etching depth, and a microlens mesa with eight steps is formed after ICP etching the relief;

Step 6: Photolithography and etching of sixteen-step microlenses. The shadow part of the fourth photolithography mask is designed to be eight parts. After photolithography, the eight mesas etched in the third etching are covered and protected with photoresist respectively. A part of the ICP etching depth is half of the third etching depth, and a microlens mesa with sixteen steps is formed after ICP etching the relief glue;

Step 7: Chemical etching molding. After cleaning and drying the etched microlens table with 16 steps, use 5% bromine-ethanol solution at room temperature for chemical wet etching molding to etch away the vertical edges and corners on the steps. , forming a microlens spherical surface with bright surface, small damage and uniform curvature radius.