CN101640231B - Mesa passivation method of infrared two-color HgCdTe detector - Google Patents

Abstract

The invention discloses a mesa passivation method of an infrared two-color HgCdTe detector, comprising the following steps: step A, eroding bare HgCdTe on a chip mesa of the two-color HgCdTe detector, eliminating a physical damage membrane and removing a zinc sulfide membrane layer on the surface; step B, carrying out passivation processing on the processed chip mesa in step A by magnetron sputtering equipment; and on the basis of a plane monochrome passivation process of the HgCdTe, selecting the magnetron sputtering equipment to carry out system optimization on key parameters such as sputtering pressure, distance among targets and the like in combination with an optimized mesa wet-chemical pretreatment process and to finally obtain good passivation effect on the surface and the side faces.

Description

Mesa passivation method of infrared two-color HgCdTe detector

Technical field

The present invention relates to two-color HgCdTe Infrared Detectors technical field, relate in particular to a kind of mesa passivation method of infrared two-color HgCdTe detector.

Background technology

The two-color HgCdTe Infrared Detectors can be surveyed the signal of two wave bands simultaneously, help more accurately judging following the trail of the objective, and passivating technique is one of key technology of research and development double-color detector.Good surface passivation technology can reduce the mercury cadmium telluride surface damage, and the interfacial state on decision HgCdTe device surface reduces the device surface leakage current.And tracking current accounts for the major part of mercury cadmium telluride reverse saturation current.The passivation layer of densification, high resistant can well reduce HgCdTe device surface recombination velocity and 1/f noise effect, improves detector dynamic electric resistor and reverse breakdown voltage, improves device performance greatly.

For two-color HgCdTe detector spare; Not only to solve the surface leakage flow problem in the lane monochromator spare (being the chip of detector); Can produce a large amount of blemish but also exist through the exposed mercury cadmium telluride table top sidewall after the deep mesa etching; Side generation-recombination current is that double-colored device creepage is a most important factor, thereby reduces device performance.Hg-Te is good for and is very easy to fracture in the mercury cadmium telluride, after dark dry etching goes out table top, can cause a large amount of Hg-Te bond fissions because of the ion bombardment in the dry etch process, thereby produce unsettled Hg atom and Hg room, produces the certain physical damage.The passivation film of growing high-quality can be protected the mercury cadmium telluride table top sidewall that exposes out, and suitable passivation technology can improve part table sidewall leakage stream situation.Its critical technological point is: side and surface combination place are easy to receive wiping force and cause surface passivation layer to be started during cleaning; Thereby cause the surface passivation layer large tracts of land to come off, the passivation layer growth of table top side direction very easily causes the inhomogeneous of thickness and structure owing to receive the influence of shadow effect; Influence the passivation layer quality; Particularly sidewall and surface combination place phenomenon of rupture occurs easily because rete is too thin, thereby cause the mercury cadmium telluride surface exposure, produce bigger tracking current.

Summary of the invention

In view of above-mentioned analysis, the present invention aims to provide a kind of mesa passivation method of infrared two-color HgCdTe detector, in order to solve the problem of the passivation technology weak effect that exists in the prior art.

The object of the invention is mainly realized through following technical scheme:

The invention provides a kind of mesa passivation method of infrared two-color HgCdTe detector, comprising:

Steps A: the mercury cadmium telluride exposed to the chip table of two-color HgCdTe detector corrodes, and eliminates the physical damnification film, removes surperficial zinc sulphide rete;

Step B: utilize magnetron sputtering apparatus to carrying out Passivation Treatment through the chip table after the processing of step A.

Further, said steps A specifically comprises:

The chip table surface of tellurium two-color HgCdTe detector is protected with photoresist, utilized the exposed mercury cadmium telluride in bromine methyl alcohol oppose side wall and bottom surface to corrode, eliminate the physical damnification rete;

Remove photoresist, utilize hcl corrosion surface zinc sulphide rete, dehydration dries up.

Further, said step B specifically comprises:

Dwindle between the target of chip sample and target distance to distance value between pre-determined target, and the chip sample that dries up is fixed on the sample disc;

Vacuum chamber is vacuumized processing, make it reach the predetermined base vacuum value of magnetron sputtering apparatus;

In vacuum chamber, charge into argon gas through gas circuit, regulate accommodation and be in half-open position, strengthen sputtering pressure, make that the gas pressure in the vacuum chamber reaches predetermined sputtering pressure value;

Through successively choosing the power of radio-frequency power supply, growth tellurium cadmium layer and zinc sulphide rete for twice.

Wherein, distance value is 70mm between said pre-determined target, and said predetermined sputtering pressure value is 1.5pa.

Beneficial effect of the present invention is following:

The present invention adopts photoresist protection table top positive, utilizes bromine methyl alcohol corrosion sidewall and bottom surface, in conjunction with magnetically controlled sputter method; Add distance between large sample and the target; Strengthen sputtering pressure, the composite passivated rete of growth CdTe/ZnS solves two-color HgCdTe detector mesa passivation technical problem well.

Other features and advantages of the present invention will be set forth in specification subsequently, and from specification, becoming apparent of part perhaps understood by embodiment of the present invention.The object of the invention can be realized through the structure that in the specification of being write, claims and accompanying drawing, is particularly pointed out and obtained with other advantages.

Description of drawings

Fig. 1 is the structural representation of magnetron sputtering apparatus;

Fig. 2 is the schematic flow sheet of the said method of the embodiment of the invention;

Fig. 3 is in the embodiment of the invention, shortens between target and the sample apart from increasing the incident angle sketch map that is got into step by sputtering particle.

Embodiment

The present invention is on the basis of the monochromatic passivation technology in mercury cadmium telluride plane; Select magnetron sputtering apparatus; Table top wet-chemical pretreating process in conjunction with optimizing carries out system optimization to key parameters such as distances between sputtering pressure and target, finally obtains good table side passivation effect.

Specifically describe preferential embodiment of the present invention below in conjunction with accompanying drawing, wherein, accompanying drawing constitutes the application's part, and is used to explain principle of the present invention with embodiments of the invention.For clear and simplification purpose, when it possibly make theme of the present invention smudgy, with specifying in detail of known function and structure in the omission device described herein.

For the ease of understanding the embodiment of the invention, the magnetron sputtering apparatus that at first embodiment of the invention is related to carries out brief description.

As shown in Figure 1, Fig. 1 is the structural representation of magnetron sputtering apparatus, specifically comprises: sample disc 1, gas circuit 2, accommodation 3, radio-frequency power supply 4, matching box 5, target 6, observation window 7 and vacuum chamber 8; Wherein, sample disc 1 is used for placing chip sample, and gas circuit 2 is ventilation bodies; Flexible 3 are used for the adjustments of gas flow; Radio-frequency power supply 4 is used for producing radio frequency, and matching box 5 is used for regulating the power of radio frequency, and target 6 is by the target material of sputter; Observation window 7 is used for observing the aura situation, and vacuum chamber 8 is used to provide the high vacuum environment of growth needs.

Below in conjunction with accompanying drawing the said method of the embodiment of the invention is elaborated.

As shown in Figure 2, Fig. 2 is the schematic flow sheet of the said method of the embodiment of the invention,, specifically can may further comprise the steps as embodiment with mercury cadmium telluride table top sample:

Step 201: preliminary treatment before the passivation; Be exactly specifically, the mercury cadmium telluride mesa surfaces of chip sample is protected with photoresist, utilize 0.5% bromine methyl alcohol corrosion 10 seconds～50 seconds, the exposed HgCdTe in oppose side wall and bottom surface corrodes, and eliminates 1～3 micron of physical damnification rete; Remove photoresist then, utilize 70% hcl corrosion surface ZnS rete 5 seconds～20 seconds, dehydration dries up.

Step 202: the target spacing is regulated; Be exactly specifically, sample disc 1 is regulated at 50mm～120mm with the spacing of target 6, and for example, spacing is 70mm.As shown in Figure 3, distance increases the incident angle sketch map that is got into step by sputtering particle (CdTe/ZnS particle cluster) to Fig. 3 between target and the sample in order to shorten, $\mathrm{\&theta;}1=\mathrm{Arctg}\frac{\mathrm{<figure-callout\; id="1"\; label="L\; h"\; filenames="H2009100921890E00011.png"\; state="\{\{state\}\}">L</figure-callout>}}{h},$ $\mathrm{\&theta;}2=\mathrm{Arctg}\frac{\mathrm{<figure-callout\; id="2"\; label="L\; h"\; filenames="H2009100921890E00011.png"\; state="\{\{state\}\}">L</figure-callout>}}{h},$ Because so h1＞h2 is θ 1＜θ 2.

Step 203: sample load; Be exactly specifically, the chip sample that dries up is fixed on the sample disc 1, vacuumize then, vacuum chamber 8 reaches the predetermined base vacuum value (vacuum degree is higher than 5E-5Pa) of equipment.

Step 204: beginning Passivation Treatment; Be exactly specifically, process gas is selected Ar gas for use, is about 10～80Sccm through gas circuit 2 flows, chooses than atmospheric pressure, regulates flexible 3 and is in half-open position, makes that the gas sputtering pressure is reached for 1～1.5Pa in the vacuum chamber 8, and for example, sputtering pressure is 1.5pa; Radio-frequency power supply 4 is chosen 50-200W earlier, the CdTe layer of growth 1000～5000A; Radio-frequency power supply 4 is chosen 100～300W, the ZnS rete of growth 1000～5000A.

Step 205: observe growing state through observation window 7, when growth reaches requirement, take out chip sample.

In sum, the embodiment of the invention provides a kind of mesa passivation method of infrared two-color HgCdTe detector, adopts photoresist protection table top positive; Utilize bromine methyl alcohol corrosion sidewall and bottom surface; In conjunction with magnetically controlled sputter method, add distance between large sample and the target, strengthen sputtering pressure; The composite passivated rete of growth CdTe/ZnS solves two-color HgCdTe detector mesa passivation technical problem.Present magnetron sputtering passivation technology has broken through to side table thickness ratio and has reached 80%, and step covers good, for reducing table side recombination rate, obtains high R0A, raising integral device performance.

Double-colored table top detector needs oppose side wall and the exposed HgCdTe in bottom surface to corrode, and eliminates the physical damnification rete, does not hope simultaneously to erode positive CdTe rete, removes surperficial ZNS rete then, carries out the composite film growth on this basis.Bromine methyl alcohol has corrosiveness preferably to mercury cadmium telluride, also can certain reaction take place to the ZnS rete, and the protection surface utilizes bromine methyl alcohol corrosion mercury cadmium telluride surface damage layer with photoresist, reaches and damages the rete removal effect preferably; Hydrochloric acid has corrosiveness preferably to the ZnS rete, and can not produce corrosion to mercury cadmium telluride and CdTe rete, utilizes hcl corrosion ZnS rete can reach positive and is in the same passive state of treating with the side.

The magnetron sputtering mode is compared with general plated film mode, have the characteristics of high speed, low temperature, low damage, and deposition rate is fast, in the technical process substrate temperature rise low, little to the damage of rete, be fit to exposed mercury cadmium telluride surface passivation.The CdTe/ZnS composite film can guarantee and mercury cadmium telluride lattice surface coupling, also can guarantee the passivation insulation effect, is fit to exposed mercury cadmium telluride surface passivation.Improving sputtering pressure can increase by sputtering particle and the formation scattering of argon ion bump back, improves growth rete directivity; Shorten between target and the sample apart from increasing the incident angle that is got into step by sputtering particle, through the above technological influence that table top side direction passivation layer receives shadow effect, the problem in uneven thickness of generation of solving.

The above; Be merely the preferable embodiment of the present invention, but protection scope of the present invention is not limited thereto, any technical staff who is familiar with the present technique field is in the technical scope that the present invention discloses; The variation that can expect easily or replacement all should be encompassed within protection scope of the present invention.Therefore, protection scope of the present invention should be as the criterion with the protection range of claims.

Claims (3)

1. a mesa passivation method of infrared two-color HgCdTe detector is characterized in that, comprising:

Steps A: the mercury cadmium telluride exposed to the chip table of two-color HgCdTe detector corrodes, and eliminates the physical damnification film, removes surperficial zinc sulphide rete;

Step B: utilize magnetron sputtering apparatus to carrying out Passivation Treatment through the chip table after the processing of step A;

Wherein, said steps A specifically comprises:

The chip table surface of two-color HgCdTe detector is protected with photoresist, utilized the exposed mercury cadmium telluride in bromine methyl alcohol oppose side wall and bottom surface to corrode, eliminate the physical damnification rete;

Remove photoresist, utilize hcl corrosion surface zinc sulphide rete, dehydration dries up;

Said step B specifically comprises:

Dwindle between the target of chip sample and target distance to distance value between pre-determined target, and the chip sample that dries up is fixed on the sample disc;

Vacuum chamber is vacuumized processing, make it reach the predetermined base vacuum value of magnetron sputtering apparatus;

In vacuum chamber, charge into argon gas through gas circuit, regulate accommodation and be in half-open position, strengthen sputtering pressure, make that the gas pressure in the vacuum chamber reaches predetermined sputtering pressure value;

Through successively choosing the power of radio-frequency power supply, growth tellurium cadmium layer and zinc sulphide rete for twice.

2. method according to claim 1 is characterized in that, distance value is 70mm between said pre-determined target.

3. method according to claim 1 is characterized in that, said predetermined sputtering pressure value is 1.5pa.

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