CN103904161A - Preparation method for area array of double-grating and bicolor quantum well infrared detector - Google Patents

Abstract

A method for manufacturing a double-grating double-color quantum well infrared detector area array, comprising: sequentially growing a lower contact layer, a lower quantum well layer, an intermediate contact layer, an upper quantum well layer and an upper contact layer on a substrate; making a front grating, And make the upper electrode; etch to form the isolation groove and the upper mesa; etch the side wall on one side of each isolation groove to form the middle mesa, etch the side wall on the other side of each isolation groove to form the lower mesa; make the middle Electrode, make the lower electrode to form the substrate; grow a passivation layer; grow the lead metal layer, lead the middle electrode, the lower electrode and the upper electrode to the upper table; grow the secondary passivation layer on the secondary passivation layer Lead holes are etched out, and thickened metal is grown in the lead holes to form a sample; the sample is divided into area array dies and interconnected with the readout circuit; the back grating is fabricated on the back of the substrate. In the structure that each picture element can lead out infrared signals of two bands at the same time, the invention makes the two bands have high grating coupling efficiency and improves the performance of the device.

Description

Fabrication method of double-grating double-color quantum well infrared detector area array

technical field

The invention belongs to the technical field of manufacturing semiconductor devices, in particular to a method for manufacturing a double-grating double-color quantum well infrared detector area array.

Background technique

Quantum well infrared detectors, especially two-color quantum well infrared detectors, are one of the focuses of detector research in recent years. The principle is to use the alternate growth of wide band gap materials with different band gaps to form a quantum well structure, and use the subband transitions in the quantum wells to make infrared detectors. By adjusting the width of the well, the height of the potential barrier, that is, the composition of the III-V compound, the position of the neutron band in the quantum well can be adjusted, and then the response wavelength of the detector can be adjusted. Using the mature growth process of III-V materials, it is easy to realize two-color detection.

In the quantum well infrared detector array, the preparation of the coupling grating is very important, and the coupling efficiency of the coupling grating directly affects the performance of the detector. In the two-color quantum well infrared detector array, the coupling grating needs to efficiently couple the infrared radiation of the two bands, so the design and preparation of the coupling grating are more complicated and difficult. At present, in the preparation of the two-color quantum well infrared detector array, the design and manufacture methods of the coupling grating mainly include:

1) Use the method of interlaced output. In the output row where the detector far away from the substrate (upper detector) works, because the upper detector is very close to the upper surface of the material, the coupling grating is made in the upper contact layer; while in the detector near the substrate (lower In the output row where the detector) works, because the lower detector is far away from the upper surface of the material, the depth of the coupling grating is deepened, and the upper detector is penetrated from the surface to reach the middle contact layer. In this method, the depth of the grating of the lower detector is very deep, and the size of the grating is small, so etching with a high aspect ratio is required, which greatly increases the difficulty of the process. Moreover, since the detectors of different bands use coupling gratings of different depths, each pixel can only output one band, and the duty cycle of the entire device is low, which greatly reduces the imaging quality of the two-color detector area array.

2) The two detection bands on the entire array share the same grating. Each pixel in the detector array simultaneously elicits infrared signals of two bands, and the grating is only prepared in the upper contact layer, and the upper detector and the lower detector share this grating. In this method, each pixel can lead out infrared signals of two bands at the same time, and the duty ratio of the area array device is high. But since the grating is only in the upper contact layer, the lower detector is far away from the grating, and the coupling efficiency is greatly reduced.

Contents of the invention

The purpose of the present invention is to provide a method for making a double-grating double-color quantum well infrared detector area array, which adopts the method of preparing gratings on the front and back sides of the area array, and can simultaneously lead out two bands of infrared signals in each pixel. In the structure, the two wavelength bands have high grating coupling efficiency, and the performance of the device is improved.

The invention provides a method for manufacturing a double-grating double-color quantum well infrared detector area array, comprising the following steps:

(A) growing a lower contact layer, a lower quantum well layer, an intermediate contact layer, an upper quantum well layer and an upper contact layer sequentially on a substrate;

(B) making a front grating on the upper contact layer, and depositing a metal layer on the front grating, which is an upper electrode;

(C) Etching downward on the metal layer to form an isolation groove and an upper mesa, and the etching depth reaches the substrate, so that the pixels on both sides of the isolation groove are completely isolated;

(D) Etching the sidewall on one side of each isolation groove, the etching depth reaches the middle contact layer, forming a mesa, etching the sidewall on the other side of each isolation groove, the etching depth reaches the lower contact layer, form the lower table;

(E) making an intermediate electrode on the middle table, and making a lower electrode on the lower table to form a substrate;

(F) growing a passivation layer on the surface of the substrate, and corroding electrode holes at the middle electrode, lower electrode and upper electrode corresponding to the passivation layer;

(G) growing and drawing out a metal layer on the surface of the passivation layer, and drawing out the middle electrode, the lower electrode and the upper electrode to the upper table;

(H) growing a secondary passivation layer on the surface of the substrate from which the metal layer is drawn, corroding a lead hole on the secondary passivation layer, and growing a thickened metal in the lead hole to form a sample;

(1) Divide the sample into area array dies, and interconnect with the readout circuit;

(J) substrate thinning is carried out to the tube core of area array;

(K) fabricating a back grating on the back of the thinned substrate to complete the preparation.

The beneficial effect of the invention is that, in the two-color quantum well infrared detector, by adopting the method of preparing gratings on both the front and back sides, the two wave bands have high grating coupling efficiency, and the performance of the device is improved.

Description of drawings

In order to further illustrate the technical content of the present invention, the following in conjunction with examples and accompanying drawings are described in detail as follows, wherein:

Fig. 1 is the preparation method flowchart of the present invention;

FIG. 2 is a schematic diagram of the device structure after the device is fabricated.

Detailed ways

Please refer to Fig. 1 and shown in Fig. 2, the present invention provides a kind of preparation method of double-grating two-color quantum well infrared detector array, comprises the steps:

(A) On a substrate 10, a lower contact layer 11, a lower quantum well layer 12, an intermediate contact layer 13, an upper quantum well layer 14 and an upper contact layer 15 are grown sequentially, and the material of the substrate 10 is semi-insulating arsenic Gallium chloride, the upper quantum well layer 14 and the lower quantum well layer 12 are multi-period quantum well structures, which are respectively the active regions of the upper and lower detectors, and the material is a binary or tertiary compound containing indium, gallium, arsenic, and aluminum. Elementary compound, the number of periods is 25-50, the material of the lower contact layer 11, the middle contact layer 13 and the upper contact layer 15 is heavily doped n-type gallium arsenide, and the doping concentration is higher than or equal to 5×10 ¹⁷ cm ^-3 , the middle contact layer 13 is used to make common ohmic contact electrodes for the upper and lower detectors, and the upper contact layer 15 and lower contact layer 11 are used to make independent ohmic contact electrodes for the upper and lower detectors respectively.

(B) Make a front grating 151 on the upper contact layer 15, and deposit a metal layer 152 on the front grating 151, this metal layer 152 is an upper electrode, and the effect of the grating 151 is to couple normal incident infrared radiation, so that it can Absorbed by the quantum well material, the material of the metal layer 152 is gold-germanium-nickel alloy, which is used as the upper electrode and reflective layer of the device;

(c) Etching downward on the metal layer 152 to form an isolation groove and an upper mesa 153, the etching depth reaches the substrate 10, so that the pixels on both sides of the isolation groove are completely isolated;

(D) Etching the sidewall on one side of each isolation groove to an etching depth reaching the middle contact layer 13 to form a mesa 131, and etching the sidewall on the other side of each isolation groove to an etching depth reaching the lower contact layer Inside 11, a lower table 111 is formed;

(E) Fabricate an intermediate electrode 132 on the middle mesa 131, and fabricate a lower electrode 112 on the lower mesa 111 to form a substrate. The materials of the intermediate electrode 132 and the lower electrode 112 are gold-germanium-nickel alloy.

(F) grow a passivation layer 16 on the surface of the substrate, etch out electrode holes at the middle electrode, lower electrode and upper electrode corresponding to the passivation layer 16, and the material of the passivation layer 16 is silicon dioxide;

(G) Growing an extraction metal layer 17 on the surface of the passivation layer 16 to extract the middle electrode 132 , the lower electrode 112 and the upper electrode 152 to the upper mesa 153 , and the extraction metal layer 17 is titanium gold.

(H) grow a secondary passivation layer 18 on the substrate surface of the lead metal layer 17, corrode a lead hole on the secondary passivation layer 18, and grow a thickened metal in the lead hole to form a sample, the thickened The metal is titanium gold;

(1) the die piece is divided into the tube core of area array, and this tube core is interconnected with readout circuit 19;

(J) Thinning the substrate 10 for the die of the area array;

(K) making a back grating 101 on the back side of the thinned substrate 10;

The specific embodiments described above have further described the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention, and are not intended to limit the present invention. Within the spirit and principles of the present invention, any modifications, equivalent replacements, improvements, etc., shall be included in the protection scope of the present invention.

Claims (6)

1. A method for making a double-grating double-color quantum well infrared detector area array, comprising the steps: (A) growing a lower contact layer, a lower quantum well layer, an intermediate contact layer, an upper quantum well layer and an upper contact layer sequentially on a substrate; (B) making a front grating on the upper contact layer, and depositing a metal layer on the front grating, which is an upper electrode; (c) Etching downward on the metal layer to form an isolation groove and an upper mesa, the etching depth reaches the substrate, so that the pixels on both sides of the isolation groove are completely isolated; (D) Etching the sidewall on one side of each isolation groove, the etching depth reaches the middle contact layer, forming a mesa, etching the sidewall on the other side of each isolation groove, the etching depth reaches the lower contact layer, form the lower table; (E) making an intermediate electrode on the middle table, and making a lower electrode on the lower table to form a substrate; (F) growing a passivation layer on the surface of the substrate, and corroding electrode holes at the middle electrode, lower electrode and upper electrode corresponding to the passivation layer; (G) growing and drawing out a metal layer on the surface of the passivation layer, and drawing out the middle electrode, the lower electrode and the upper electrode to the upper table; (H) growing a secondary passivation layer on the surface of the substrate from which the metal layer is drawn, corroding a lead hole on the secondary passivation layer, and growing a thickened metal in the lead hole to form a sample; (1) Divide the sample into area array dies, and interconnect with the readout circuit; (J) substrate thinning is carried out to the tube core of area array; (K) fabricating a back grating on the back of the thinned substrate to complete the preparation. 2. The method for making the double-grating double-color quantum well infrared detector array according to claim 1, wherein the material of the substrate is semi-insulating gallium arsenide. 3. The manufacturing method of the double-grating double-color quantum well infrared detector array according to claim 1, wherein the material of the lower contact layer, the middle contact layer and the upper contact layer is n-type gallium arsenide. 4. The manufacturing method of the double-grating double-color quantum well infrared detector array according to claim 1, wherein said lower quantum well layer and upper quantum well layer are multi-period structures. 5. the manufacture method of double-grating two-color quantum well infrared detector area array according to claim 1, wherein the metal directly contacting with semiconductor material on upper mesa, middle mesa and lower mesa is gold-germanium-nickel alloy. 6. The fabrication method of double-grating double-color quantum well infrared detector area array according to claim 1, wherein drawing out metal layer and thickening metal is titanium gold.

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