ALD composite dielectric film for improving stability of infrared detector chip and preparation method of ALD composite dielectric film

Abstract

The invention discloses an ALD composite dielectric film for improving the stability of an infrared detector chip and a preparation method, the composite dielectric film comprises inorganic dielectric film layers located at the first layer and the last layer and a plurality of organic dielectric film layers located between the two inorganic dielectric film layers, and the method comprises the following steps: sending a chip into an ALD cavity; introducing an aluminum source precursor and an oxygen source, and repeating the step so as to obtain a first layer of smooth and uniform inorganic dielectric film on the surface of the chip through atomic layer deposition; introducing an organic matter source, and repeating the step to obtain a second layer of smooth and uniform organic dielectric film on the surface of the chip; and repeatedly executing the inorganic dielectric film and the organic dielectric film of the corresponding period number until the inorganic / organic composite dielectric film layer with the expected thickness is obtained on the surface of the chip. According to the composite dielectric film layer prepared by the method provided by the invention, the stability of the chip can be improved while passivation is realized.

Description

Technical Field

[0001] The present invention relates to the field of infrared detectors, and particularly to an ALD composite dielectric film for improving the stability of an infrared detector chip and a preparation method thereof. Background Art

[0002] Surface passivation is one of the key technologies of infrared detectors. The surface passivation layer can protect the material surface from being eroded by moisture, oxygen and other harmful substances in the environment. The carrier lifetime of the material is jointly affected by the surface and bulk recombination mechanisms. High-quality surface passivation can reduce the surface recombination rate, thereby increasing the carrier lifetime, reducing the surface leakage current of the device, and improving the detection rate and electrical stability of the device.

[0003] Currently, the deposition of the passivation layer usually includes thermal oxidation method, chemical oxidation method, and oxidation-reduction vapor deposition method. Compared with traditional passivation technologies, when growing the passivation layer by ALD technology, the deposition temperature used is relatively low, so the passivation process has no damage to the superlattice structure; the deposited passivation layer has uniform thickness, precise element ratio, and high resistivity, and high-quality passivation of large-area array devices can be achieved; at the same time, the ALD technology has a self-limiting, isotropic and conformal process, and the process thickness can be controlled by the number of reaction cycles, and etching or growth is not affected by the mesa shape or height, and the mesa coverage can reach 100%.

[0004] However, in the prior art, the passivation films prepared by atomic layer deposition method are usually inorganic film layers, which only consider the passivation effect of the front-end process of the device, and try to ensure the isolation of the device from moisture, oxygen and other harmful substances as much as possible, obtain stable material surface states, increase the carrier lifetime, and reduce the surface leakage current of the device, mainly to improve the electrical stability of the device. In the prior art, most of the preparation of organic thin films uses the spin coating method. Although this method has the advantages of simple operation and low cost, it is difficult to prepare thin films on curved surfaces or substrates with mesa patterns; at the same time, for advanced micro-nano manufacturing processes, it is difficult to control the precision and uniformity of the thin films prepared by the spin coating method.

[0005] CN 117402392 A discloses a method and device for preparing an alumina passivation film by ALD method. The preparation method includes providing a substrate and feeding it into a reaction chamber; introducing trimethylaluminum into the reaction chamber while introducing aluminum trichloride; introducing nitrogen into the reaction chamber to purge the reaction chamber, and contacting the blown-out gas with water in a container; introducing water vapor into the reaction chamber; introducing nitrogen into the reaction chamber to purge the reaction chamber; the above steps form a cycle, repeating this cycle to obtain an alumina thin film. By improving the deposition efficiency of trimethylaluminum, reducing the remaining amount of trimethylaluminum, and after the deposition of trimethylaluminum, allowing trimethylaluminum to react with water within a controllable range to eliminate uncontrollable safety risks. Improve the safety of preparing an alumina passivation film by ALD process. However, this type of passivation structure only considers the stability of the front-end single-step passivation process and does not consider the compatibility and stability with the back-end processes (such as flip-chip bonding), which poses a potential hazard to the overall working stability of the chipset and the whole machine.

[0006] CN 117926223 A discloses an atomic layer penetration deposition composite film with strong AI-O bonding, including an organic layer, an organic-inorganic hybrid layer, and an inorganic layer. The organic layer is PET, PEN or PI, the inorganic layer is alumina, titanium oxide or zirconia, and the organic-inorganic hybrid layer is a composite layer formed by the organic layer and the inorganic layer. The present invention provides a method for improving the adhesion ability of an inorganic coating material inside and on the surface of an organic substrate. This method is used to form a compact organic-inorganic hybrid layer with AI-O bonding inside the flexible substrate and an inorganic thin film layer with AI-O bonding on the surface of the flexible substrate. The present invention relates to corona treating a flexible substrate to improve the adhesion and bonding ability of an inorganic coating on the surface and inside the flexible substrate, and is particularly applicable to the encapsulation application scenario of a modified alumina composite film. However, this type of composite film only considers the adhesion ability of the coating process and does not study the passivation coating effect at the front end of the device. Summary of the Invention

[0007] Aiming at the above-mentioned defects and deficiencies existing in the prior art, the purpose of the present invention is to provide an ALD composite dielectric film and a preparation method for improving the stability of an infrared detector chip. An inorganic / organic composite dielectric film layer is deposited on the surface of a device material by atomic layer deposition technology to form a composite dielectric film. The composite dielectric film includes inorganic dielectric film layers at the first layer and the last layer and several organic dielectric film layers located between the two inorganic dielectric film layers; this composite dielectric film not only ensures the passivation effect of the inorganic film layer but also is compatible with the stability of back-end processes such as flip-chip bonding.

[0008] To achieve the above-mentioned invention purpose, the present invention is implemented by adopting the following technical solutions:

[0009] A method for improving the stability of an infrared detector chip by atomic layer deposition of a dielectric film, the method comprising the following steps:

[0010] Step (S.1): Provide an infrared detector chip to be passivated, and send the chip into the atomic layer deposition reaction chamber. Subsequently, evacuate the inside of the atomic layer deposition reaction chamber and control the temperature.

[0011] Step (S.2): Sequentially and cyclically pulse-feed an aluminum source precursor and an oxygen source into the atomic layer deposition reaction chamber, and use a purge gas for purging during the interval between the introduction of the aluminum source and the oxygen source. Repeat this step to obtain a first smooth and uniform inorganic dielectric film on the chip surface by atomic layer deposition.

[0012] Step (S.3): Sequentially and cyclically pulse-feed an organic source into the atomic layer deposition reaction chamber, and use a purge gas for purging during the interval between the introduction of the organic source. Repeat this step to obtain a second smooth and uniform organic dielectric film on the chip surface by atomic layer deposition.

[0013] Step (S.4): Repeat steps (S.2) and (S.3) for a corresponding number of cycles until an inorganic / organic composite dielectric film layer of the desired thickness is obtained on the chip surface.

[0014] In the above method, the structure of the infrared detector chip can be a planar junction structure or a mesa junction structure.

[0015] In the above method, in step (S.1), the internal vacuum degree of the reaction chamber of the atomic layer deposition equipment for depositing the dielectric film is in the range of 7 - 200 Pa. The temperature control for depositing the dielectric film inside the reaction chamber is in the range of 50 - 400 °C.

[0016] In the above method, in step (S.2), the aluminum source for atomic layer deposition of the passivation layer is one of trimethylaluminum, triethylaluminum, triethoxyaluminum, or aluminum trichloride. The oxygen source is one of oxygen, ozone, water, or hydrogen peroxide. The pulse time of the aluminum source and the oxygen source is 0.06 - 10 s, preferably 0.06 - 1 s; the purge time is 2 - 10 s, preferably 2 - 4 s; the deposition rate of the inorganic dielectric film is preferably

[0017] In the above method, in step (S.3), the organic source includes, but is not limited to, p-phenylene diisocyanate (PDIC) and ethylenediamine (ED), and the organic passivation layer includes, but is not limited to, polyimide (PI) or polyurethane (PU) organic polymer thin films. The pulse time of the organic source is 5 - 10 s, preferably 5 - 8 s; the purge time is 5 - 30 s, preferably 8 - 12 s; the deposition rate of the organic dielectric film is preferably

[0018] In the above method, the minimum number of depositions of the inorganic passivation layer in step (S.4) described in step (S.2) is 2. The first and last layers of the composite dielectric film layer are inorganic dielectric films. The minimum number of depositions in step (S.3) is 1. The organic dielectric film layer is located between two inorganic dielectric films; the minimum thickness of the composite film layer is 30 nm.

[0019] The beneficial effects of the present invention are as follows:

[0020] The ALD composite dielectric film of the present invention uses atomic layer deposition technology to deposit an inorganic / organic composite dielectric film layer on the surface of a device material to form a composite dielectric film. First, it has the advantages of easy control of the accuracy and uniformity of each thin film and strong adhesion ability. At the same time, the first layer of the composite dielectric film structure of the present invention is an inorganic passivation layer, and the passivation interface state of the detector chip has not changed, thus ensuring the passivation effect of the chip. The second layer is an organic dielectric film. The organic material is softer than the inorganic dielectric film and can play a buffering role in the subsequent process (such as flip-chip bonding), improving the process tolerance and achieving the effect of improving the stability of the infrared detector chip. An inorganic dielectric film continues to grow on top of the organic dielectric film because the organic material is easily aged or denatured when directly exposed to the environment, and the inorganic dielectric film plays a role in protecting the organic dielectric film. Therefore, the last layer grown in the composite dielectric film is an inorganic dielectric film. At the same time, this composite dielectric film layer can also effectively reduce the stress of the passivation film layer, which is also extremely beneficial to the stability of the infrared detector chip. Description of the Drawings

[0021] Figure 1 : Schematic diagram of the 5-layer composite dielectric film layer structure of thermal atomic layer deposition.

[0022] Figure 2 : Schematic diagram of the 3-layer composite dielectric film layer structure of plasma-enhanced atomic layer deposition of inorganic passivation layer and thermal atomic layer deposition of organic passivation layer.

[0023] Figure 3 : Microscope photo of the damage after flip-chip bonding of a single-layer inorganic dielectric film on the mesa of an infrared detector chip.

[0024] Figure 4 : Microscope photo of the flip-chip bonding of the composite dielectric film on the mesa of an infrared detector chip.

[0025] Figure 5 : Test signal diagram of an infrared detector chip with damaged flip-chip bonding of a single-layer inorganic dielectric film on the mesa.

[0026] Figure 6 : Test signal diagram of an infrared detector chip with a composite dielectric film on the mesa. Detailed Embodiments

[0027] The present invention will be further described below in conjunction with specific embodiments. Those of ordinary skill in the art will be able to implement the present invention based on these descriptions. In addition, the embodiments of the present invention involved in the following description are generally only part of the embodiments of the present invention, rather than all of the embodiments. Therefore, all other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0028] Embodiment 1:

[0029] A method for improving the stability of an infrared detector chip by atomic layer deposition of a dielectric film. The thermal atomic layer deposition process is adopted in this embodiment, which includes the following steps:

[0030] Step (S.1): Provide an infrared detector chip to be passivated, and send the chip into the atomic layer deposition reaction chamber. Then, evacuate the inside of the atomic layer deposition reaction chamber to 20 Pa, and control the internal temperature of the reaction chamber to 200 °C.

[0031] Step (S.2): Pulse-feed trimethylaluminum, the aluminum source precursor, and deionized water, the oxygen source, into the atomic layer deposition reaction chamber at 0.06 s intervals, and use purge gas N2 for purging during the interval between the introduction of the aluminum source and the oxygen source. The purging time is 2 s, and repeat this step 300 times. Thus, a first smooth and uniform inorganic dielectric film Al2O3 is obtained on the chip surface by atomic layer deposition. The growth rate of the inorganic dielectric film Al2O3 is

[0032] Step (S.3): Evacuate the inside of the atomic layer deposition reaction chamber to 20 Pa, and control the internal temperature of the reaction chamber to 70 °C. Pulse-feed p-phenylene diisocyanate (PDIC) and ethylenediamine (ED), the organic source materials, into the atomic layer deposition reaction chamber at 5 s intervals to prepare a PU organic passivation film, and use purge gas for purging during the interval between the introduction of the organic source materials. The purging time is 10 s, and repeat this step 500 times. Thus, a second smooth and uniform organic dielectric film is obtained on the chip surface by atomic layer deposition. The growth rate of the organic dielectric film PU is

[0033] Step (S.4): Repeat step (S.2) 3 times and step (S.3) 2 times for the corresponding number of cycles to obtain a 5-layer inorganic / organic composite dielectric film layer on the chip surface as Figure 1 shown.

[0034] Embodiment 2:

[0035] A method for improving the stability of an infrared detector chip by atomic layer deposition of a dielectric film. In this embodiment, an ion-enhanced atomic layer deposition process is adopted for the inorganic dielectric film, which includes the following steps:

[0036] Step (S.1): Provide an infrared detector chip to be passivated, and send the chip into the atomic layer deposition reaction chamber. Subsequently, evacuate the inside of the atomic layer deposition reaction chamber to 20 Pa, and control the internal temperature of the reaction chamber to 150 °C;

[0037] Step (S.2): Pulse-feed trimethylaluminum, the aluminum source precursor, into the atomic layer deposition reaction chamber at 0.06 s, with oxygen as the oxygen source, and the pulse-feed time is 6 s. Use purge gas N2 to purge during the interval between feeding the aluminum source and the oxygen source, and the purge time is 2 s. Repeat this step 360 times to obtain a first smooth and uniform inorganic dielectric film Al2O3 on the chip surface through atomic layer deposition; the growth rate of the inorganic dielectric film Al2O3 is

[0038] Step (S.3): Evacuate the inside of the atomic layer deposition reaction chamber to 20 Pa, and control the internal temperature of the reaction chamber to 70 °C. Pulse-feed p-phenylene diisocyanate (PDIC) and ethylenediamine (ED), the organic source materials, into the atomic layer deposition reaction chamber at 5 s to prepare a PU organic passivation film, and use purge gas to purge during the interval between feeding the organic source materials, and the purge time is 10 s. Repeat this step 1000 times to obtain a second smooth and uniform organic dielectric film on the chip surface through atomic layer deposition; the growth rate of the organic dielectric film PU is

[0039] Step (S.4): Repeat step (S.2) 2 times and step (S.3) 1 time for the corresponding number of cycles to obtain a three-layer inorganic / organic composite dielectric film layer on the chip surface as Figure 2 shown.

[0040] Comparative Example 1:

[0041] Step (S.1): Provide an infrared detector chip to be passivated, and send the chip into the atomic layer deposition reaction chamber. Subsequently, evacuate the inside of the atomic layer deposition reaction chamber to 20 Pa, and control the internal temperature of the reaction chamber to 200 °C;

[0042] Step (S.2): Pulse-feed trimethylaluminum, the aluminum source precursor, and deionized water, the oxygen source, into the atomic layer deposition reaction chamber at 0.06 s, and use purge gas N2 to purge during the interval between feeding the aluminum source and the oxygen source, and the purge time is 2 s. Repeat this step 600 times to obtain an inorganic dielectric film Al2O3 with a thickness of about 50 nm on the chip surface through atomic layer deposition; the growth rate of the inorganic dielectric film Al2O3 is

[0043] Figure 3For the inorganic dielectric film Al2O3 with a thickness of 50 nm deposited by atomic layer deposition in Comparative Example 1, the situation of film layer breakage was observed under a microscope after the flip-chip bonding process by etching away the chip material. Figure 4 It is the situation observed under a microscope after the flip-chip bonding process of the composite dielectric film layer prepared in Example 2 by etching away the chip material. Figure 6 It is the chip test signal diagram of the composite dielectric film layer. Due to the warping of the chip surface shape, in the flip-chip bonding process, the position with a large chip warping will contact the In column first, and the stress time during the process is longer. Therefore, the deformation amount of the In column is larger, and the Figure 3 situation of the breakage of the medium film layer in Figure 5 It is the chip test signal diagram of the infrared detector with breakage after flip-chip bonding of the mesa single-layer inorganic dielectric film. When we use the composite dielectric film layer, the organic dielectric film has a buffering effect during the stress process, increasing the flexibility of the dielectric film layer and the process tolerance, thereby effectively improving the stability of the infrared detector chip.

[0044] The above embodiments only illustrate the principles and effects of the present invention by way of example, and are not used to limit the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed by the present invention should still be covered by the technical solution of the present invention and the claims of the present invention.

Claims

1. An ALD composite dielectric film for improving the stability of an infrared detector chip, characterized in that, The composite dielectric film includes inorganic dielectric film layers located at the first layer and the last layer, and several organic dielectric film layers located between the two inorganic dielectric film layers; The preparation method of the composite dielectric film includes the following steps: Step (S.1): Provide an infrared detector chip to be passivated, and send the chip into the atomic layer deposition reaction chamber. Subsequently, evacuate the inside of the atomic layer deposition reaction chamber and control the temperature; Step (S.2): Sequentially and cyclically pulse-feed an aluminum source precursor and an oxygen source into the atomic layer deposition reaction chamber, and use a purge gas to purge during the interval between the introduction of the aluminum source and the oxygen source. Repeat this step to obtain a first smooth and uniform inorganic dielectric film layer on the chip surface by atomic layer deposition; Step (S.3): Sequentially and cyclically pulse-feed an organic matter source into the atomic layer deposition reaction chamber, and use a purge gas to purge during the interval between the introduction of the organic matter source. Repeat this step to obtain a second smooth and uniform organic dielectric film layer on the chip surface by atomic layer deposition; Step (S.4): Repeatedly execute steps (S.2) and (S.3) for a corresponding number of cycles until an inorganic / organic composite dielectric film layer with a desired thickness is obtained on the chip surface.

2. The ALD composite dielectric film for improving the stability of an infrared detector chip as described in claim 1, wherein: In step (S.2), the pulse time of the aluminum source precursor and the oxygen source is 0.06 - 10 s, and the purge time is 2 - 10 s.

3. The ALD composite dielectric film for improving the stability of an infrared detector chip as described in claim 1, wherein: In step (S.3), the pulse time of the organic matter source is 5 - 10 s, and the purge time is 5 - 30 s.

4. The ALD composite dielectric film for improving the stability of an infrared detector chip as described in claim 1, wherein: The inorganic dielectric film layer is an Al2O3 film layer.

5. The ALD composite dielectric film for improving the stability of an infrared detector chip as described in claim 1, wherein: The organic dielectric film layer is a polyimide or a polyurethane film layer.

6. The ALD composite dielectric film for improving the stability of an infrared detector chip as described in claim 1, wherein: In step (S.1), the evacuation inside the reaction chamber is in the range of 7 - 200 Pa; In step (S.1), the temperature control inside the reaction chamber is in the range of 50 - 400 °C.

7. The ALD composite dielectric film for improving the stability of an infrared detector chip as described in claim 1, wherein: In step (S.2), the aluminum source is one of trimethylaluminum, triethylaluminum, triethoxyaluminum, or aluminum trichloride; In step (S.2), the oxygen source is one of oxygen, ozone, water, or hydrogen peroxide; In step (S.3), the organic matter source is p-phenylene diisocyanate and ethylenediamine.

8. The ALD composite dielectric film for improving the stability of an infrared detector chip as described in claim 1, wherein: In step (S.1), the infrared detector chip has a planar junction or mesa junction structure.

9. The ALD composite dielectric film for improving the stability of an infrared detector chip according to any one of claims 1-8, characterized in that: In step (S.4), the minimum deposition number in step (S.2) is 2, and the minimum deposition number in step (S.3) is 1.

10. The ALD composite dielectric film for improving the stability of an infrared detector chip according to any one of claims 1-8, characterized in that: The minimum thickness of the composite film layer is 30 nm.

Images