Antireflection film, superlattice semiconductor chip, GaSb chip and focal plane detector

Abstract

The invention relates to the field of semiconductor chip optical thin films, in particular to an antireflection film, a superlattice semiconductor chip, a GaSb chip and a focal plane detector. The antireflection film provided by the invention has ultra-low infrared reflectivity, and is very suitable for being applied to manufacturing of semiconductor chips, especially manufacturing of semiconductor chips for detectors. According to the GaSb chip disclosed by the invention, a superlattice semiconductor GaSb material is taken as a substrate, and the eight layers of antireflection films are arranged on the GaSb substrate, so that the obtained GaSb chip has ultra-low infrared long-wave band reflectivity, and particularly, the average reflectivity is lower than 0.41% under the infrared long-wave band, particularly under the infrared long-wave band of 7.2-9.5 microns.

Description

Technical Field

[0001] The invention relates to the field of semiconductor chip optical films, in particular to an anti-reflection film, a superlattice semiconductor chip, a GaSb chip and a focal plane detector. Background Art

[0002] Since the discovery of anti-reflection film in the 1930s, the rapid development of thin film optics has been promoted. To date, the design and preparation technology of anti-reflection film still plays a very important role in the semiconductor chip manufacturing process. The design of anti-reflection film for semiconductor chips often has special requirements. For example, the semiconductor chip anti-reflection film requires certain components to have very low surface reflection and extremely high transmission effect to increase the signal strength of the detector. Therefore, the actual chip manufacturing has promoted the continuous development of anti-reflection film.

[0003] At present, the reflectivity of a single-layer zinc sulfide anti-reflection film evaporated on a 1 μm thick superlattice substrate GaSb is higher than 2%. Existing technologies attempt to use zinc sulfide and rare earth fluoride to achieve long-wave infrared anti-reflection effects, but the interaction between zinc sulfide and rare earth fluoride has a relatively complex relationship with the long-wave infrared anti-reflection effect. Different reflective film designs are difficult to predict the effect of the final product, and the problem of reflectivity higher than 2% in the infrared long-wave band has never been solved. Summary of the invention

[0004] In view of this, the technical problem to be solved by the present invention is to provide an anti-reflection film, a superlattice semiconductor chip, a GaSb chip and a focal plane detector. The average reflectivity of the anti-reflection film provided by the present invention in the infrared long-wave band is lower than 0.41%.

[0005] The present invention provides an anti-reflection film, comprising:

[0006] An inner film layer, wherein the inner film layer is composed of ZnS and has a thickness of 900 nm to 1000 nm;

[0007] A second film layer is disposed on the inner film layer, the second film layer is composed of YbF3, and the thickness of the second film layer is 1000 nm to 1100 nm;

[0008] a third film layer disposed on the second film layer, the third film layer being composed of ZnS and having a thickness of 550 nm to 650 nm;

[0009] A fourth film layer is disposed on the third film layer, the fourth film layer is composed of YbF3, and the thickness of the fourth film layer is 200 nm to 250 nm;

[0010] A fifth film layer is disposed on the fourth film layer, the fifth film layer is composed of ZnS, and the thickness of the fifth film layer is 800 nm to 900 nm;

[0011] A sixth film layer is disposed on the fifth film layer, the sixth film layer is composed of YbF3, and the thickness of the sixth film layer is 2600 nm to 2800 nm;

[0012] a seventh film layer disposed on the sixth film layer, the seventh film layer being composed of ZnS, and having a thickness of 400 nm to 450 nm;

[0013] An outer film layer is arranged on the seventh film layer, wherein the outer film layer is composed of YbF3 and has a thickness of 1500 nm to 1700 nm.

[0014] Preferably, the thickness of the inner membrane layer is 950 nm to 1000 nm;

[0015] The thickness of the second film layer is 1000 nm to 1050 nm;

[0016] The thickness of the third film layer is 580 nm to 620 nm;

[0017] The thickness of the fourth film layer is 200 nm to 220 nm;

[0018] The thickness of the fifth film layer is 800 nm to 850 nm;

[0019] The thickness of the sixth film layer is 2700 nm to 2800 nm;

[0020] The thickness of the seventh film layer is 400 nm to 420 nm;

[0021] The thickness of the outer membrane layer is 1600 nm to 1700 nm.

[0022] More preferably, the thickness of the inner membrane layer is 970.14 nm;

[0023] The thickness of the second film layer is 1035.6 nm;

[0024] The thickness of the third film layer is 600 nm;

[0025] The thickness of the fourth film layer is 212.6 nm;

[0026] The thickness of the fifth film layer is 821.56 nm;

[0027] The thickness of the sixth film layer is 2772.96 nm;

[0028] The thickness of the seventh film layer is 409.32 nm;

[0029] The thickness of the outer membrane layer is 1638.61 nm.

[0030] In the anti-reflection film of the present invention, the ZnS is specifically ZnS with a refractive index of 2.1 to 2.3 in the infrared band of 7.2 μm to 9.5 μm; the YbF3 is YbF3 with a refractive index of 1.4 to 1.5. The film layers in the anti-reflection film of the present invention are provided by a vapor deposition process, specifically, at 5×10 -6 Torr atmosphere, wherein the inner film layer, the third film layer, the fifth film layer and the seventh film layer composed of ZnS are evaporated at an evaporation rate of 4 to 6 Å per second, and the second film layer, the fourth film layer, the sixth film layer and the outer film layer are evaporated at an evaporation rate of 9 to 11 Å per second.

[0031] The anti-reflection film of the present invention is an optical film for semiconductor chips, which has a total of eight anti-reflection film designs, including four groups of ZnS film layers and YbF3 film layers, wherein the inner film layer is used as the inner layer and is arranged on the surface of the semiconductor chip substrate in practical application, and the outer film layer is used as the outer layer and the light source first enters from the outer film layer in practical application. The anti-reflection film of the present invention has an ultra-low infrared reflectivity and is very suitable for use in the manufacture of semiconductor chips, especially the manufacture of semiconductor chips for detectors.

[0032] The present invention also provides a superlattice semiconductor chip, comprising:

[0033] Superlattice semiconductor substrates and anti-reflection films;

[0034] The anti-reflection film described in the present invention is the anti-reflection film described in any of the above technical solutions.

[0035] The thickness of the superlattice semiconductor substrate of the present invention is 0.8 μm to 1.2 μm, preferably 1 μm.

[0036] The superlattice semiconductor chip of the present invention uses superlattice semiconductor material as a substrate, and the eight-layer anti-reflection film of the present invention is arranged on the superlattice semiconductor material. The obtained semiconductor chip has ultra-low infrared long-wave band reflectivity, and the detector using the semiconductor chip has high signal strength.

[0037] The method for preparing the superlattice semiconductor chip of the present invention comprises the following steps:

[0038] S1) using a Hall type ion source to perform ion cleaning pretreatment on the superlattice semiconductor substrate;

[0039] S2) using a Hall type ion source to perform auxiliary deposition in the early stage of evaporation on the superlattice semiconductor substrate after the cleaning and pretreatment in step S1);

[0040] S3) sequentially evaporating an inner film layer, a second film layer, a third film layer, a fourth film layer, a fifth film layer, a sixth film layer, a seventh film layer and an outer film layer on the superlattice semiconductor substrate after the auxiliary deposition in step S2) to obtain the superlattice semiconductor chip.

[0041] The film layers of the superlattice semiconductor chip of the present invention are arranged by a vapor deposition process, specifically, on a 5×10 -6 Torr atmosphere, wherein the inner film layer, the third film layer, the fifth film layer and the seventh film layer composed of ZnS are evaporated at an evaporation rate of 4 to 6 Å per second, and the second film layer, the fourth film layer, the sixth film layer and the outer film layer are evaporated at an evaporation rate of 9 to 11 Å per second.

[0042] The present invention also provides a GaSb chip, comprising:

[0043] GaSb substrate and anti-reflection film;

[0044] The anti-reflection film of the present invention is the anti-reflection film described in any of the above technical solutions;

[0045] The thickness of the GaSb substrate of the present invention is 0.8 μm to 1.2 μm, preferably 1 μm.

[0046] The method for preparing the GaSb chip of the present invention comprises the following steps:

[0047] S1) using a Hall type ion source to pre-treat the GaSb substrate by ion cleaning;

[0048] S2) using a Hall type ion source to perform auxiliary deposition in the early stage of evaporation on the GaSb substrate that has been cleaned and pre-treated in step S1);

[0049] S3) sequentially evaporating an inner film layer, a second film layer, a third film layer, a fourth film layer, a fifth film layer, a sixth film layer, a seventh film layer and an outer film layer on the GaSb substrate after the auxiliary deposition in step S2) to obtain the superlattice semiconductor chip.

[0050] The film layers of the GaSb chip of the present invention are provided by an evaporation process, specifically, on a 5×10 -6 Torr atmosphere, wherein the inner film layer, the third film layer, the fifth film layer and the seventh film layer composed of ZnS are evaporated at an evaporation rate of 4 to 6 Å per second, and the second film layer, the fourth film layer, the sixth film layer and the outer film layer are evaporated at an evaporation rate of 9 to 11 Å per second.

[0051] The present invention also provides a focal plane detector, the photosensitive element chip of which is the above-mentioned GaSb chip.

[0052] The present invention provides an anti-reflection film, a superlattice semiconductor chip, a GaSb chip and a focal plane detector. The anti-reflection film provided by the present invention has an ultra-low infrared reflectivity and is very suitable for the manufacture of semiconductor chips, especially the manufacture of semiconductor chips for detectors. The GaSb chip described in the present invention uses a superlattice semiconductor GaSb material as a substrate. By arranging the eight-layer anti-reflection film described in the present invention on the GaSb substrate, the obtained GaSb chip has an ultra-low infrared long-wave band reflectivity, especially in the infrared long-wave band, specifically in the infrared long-wave band of 7.2 μm to 9.5 μm, the average reflectivity is less than 0.41%. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 This is a graph showing the infrared reflectivity test results of GaSb chips provided with anti-reflection films according to Example 1 of the present invention and Comparative Example 1;

[0054] Figure 2 This is a test result diagram of the infrared reflectivity of a GaSb chip provided with an anti-reflection film according to Comparative Example 2 of the present invention;

[0055] Figure 3 This is a test result diagram of the infrared reflectivity of a GaSb chip provided with an anti-reflection film according to Comparative Example 3 of the present invention;

[0056] Figure 4 This is a graph showing the infrared reflectivity test results of a GaSb chip provided with an anti-reflection film according to Comparative Example 4 of the present invention. DETAILED DESCRIPTION

[0057] The present invention discloses an anti-reflection film, a superlattice semiconductor chip, a GaSb chip and a focal plane detector. Those skilled in the art can refer to the content of this article and appropriately improve the process parameters to achieve it. It is particularly important to point out that all similar replacements and modifications are obvious to those skilled in the art, and they are all considered to be included in the present invention. The method and application of the present invention have been described through preferred embodiments, and relevant personnel can obviously modify or appropriately change and combine the method and application of this article without departing from the content, spirit and scope of the present invention to implement and apply the technology of the present invention.

[0058] The present invention will be further described below in conjunction with embodiments:

[0059] Example 1

[0060] A GaSb chip with an anti-reflection film is designed according to the structure shown in Table 1:

[0061] Table 1

[0062]

[0063] The specific preparation steps are as follows:

[0064] 1. Prepare GaSb chip (i.e. GaSb substrate, thickness 1 μm)

[0065] 2. Place the GaSb chip on the workpiece rotating system of the vacuum chamber of the film-making equipment (resistance evaporation equipment) (place the coated GaSb chip on a special fixture with the polished surface facing downward, and then install the fixture on the workpiece rotating system of the chamber. The workpiece rotating system can drive the GaSb chip to rotate, and the process parameters during rotation can be adjusted);

[0066] 3. Evacuate the vacuum chamber to 5×10 -6 Torr;

[0067] 4. Set the speed of the workpiece rotation system between 6 and 10 revolutions per minute;

[0068] 5. Adjust the heating temperature of the workpiece plate to 60 degrees Celsius and keep it warm for 20 minutes after the temperature is reached;

[0069] 6. Set the evaporation rate of ZnS film to 5Å per second and the thickness of each layer;

[0070] 7. Set the evaporation rate of YbF3 film to 10Å per second and the thickness of each layer;

[0071] 7.1. The coating material includes zinc sulfide and ytterbium fluoride. Specifically, the coating material includes zinc sulfide with a refractive index of 2.2 and ytterbium fluoride with a refractive index of 1.48 in the infrared band of 7.2 microns to 9.5 microns.

[0072] 8. Set the cathode voltage of the Hall type ion source to 150Volt, the cathode current to 2Amps (no need to set the cathode voltage parameters), the neutralization current to between 80 and 800 mA, and the argon gas flow rate to 12sccm.

[0073] 8.1. Use Hall type ion source to pre-treat GaSb chip by ion cleaning. After the temperature is maintained for 10 minutes, the chip is bombarded with ion beam for 10 minutes. This can clean the water vapor and other pollutants adsorbed on the surface of the substrate, and change the adsorption bonds between the interfaces into covalent bonds, ionic bonds and other chemical bonds, so as to improve the surface activity, increase the nucleation density, and refine the film grains, thereby improving the adhesion between the film layer and the chip.

[0074] 8.2. After cleaning, use Hall-type ion source to assist deposition in the early stage of GaSb chip evaporation. During the ion beam bombardment, due to the momentum transfer of ions to the film particles, the energy and mobility of the film material particles are increased, the columnar structure that may be formed in the film is destroyed, the gaps are filled, the aggregation density is increased, the structural integrity is improved, the stress state is improved, and finally the performance life of the film is improved.

[0075] 9. After the ion source is cleaned and the auxiliary deposition is completed, the machine equipment is designed according to Table 1 to sequentially plate the first layer of ZnS / 970.14nm, the second layer of YbF3 / 1035.6nm, the third layer of ZnS / 600nm, the fourth layer of YbF3 / 212.6nm, the fifth layer of ZnS / 821.56nm, the sixth layer of YbF3 / 2772.96nm, the seventh layer of ZnS / 409.32nm, and the eighth layer of YbF3 / 1638.61nm, and the thermal evaporation method is continuously used to prepare the thin film.

[0076] 9.1. During the evaporation process, a crystal oscillator is used to monitor the rate and thickness of the film evaporation.

[0077] 10. After plating, take out the chip when the chamber cools down to room temperature.

[0078] 11. Perform performance test on the chip. The GaSb chip back anti-reflection film prepared by thermal evaporation method has a smooth surface, high uniformity and no film peeling.

[0079] 12. Perform film firmness certification on the back anti-reflection film of GaSb chip. This step specifically includes: soaking the back anti-reflection film of GaSb chip in boiling water for 1 minute, immediately putting it into a container filled with liquid nitrogen and soaking it for another 1 minute, performing 50 cycles of hot and cold shock, and then gluing it 50 times after 50 hot and cold shocks, and inspecting it with a NiKonSMZ645 microscope at 50 times. If there is no blistering or peeling, it is qualified.

[0080] Comparative Example 1

[0081] A single layer of ZnS with a thickness of 980 nm is plated on the surface of the GaSb substrate in the same manner as in Example 1, that is, there is only a single layer of ZnS with a thickness of 980 nm as an anti-reflection film on the GaSb substrate.

[0082] The infrared reflectivity test of the chips designed with the anti-reflection films of the above-mentioned embodiment 1 and comparative example 1 is performed, and the results are as follows: Figure 1 As shown, Figure 1This is a graph showing the infrared reflectivity test results of GaSb chips provided with anti-reflection films according to Example 1 of the present invention and Comparative Example 1. From the results, it can be seen that the average reflectivity of the four-group zinc sulfide / ytterbium fluoride film design is lower than 0.41% in the infrared long-wave band (7.2-9.5 μm), which is significantly reduced relative to the reflectivity of a single-layer zinc sulfide film.

[0083] Comparative Example 2

[0084] A GaSb chip with an anti-reflection film is designed according to the structure shown in Table 2:

[0085] Table 2

[0086]

[0087] The chip was prepared and the infrared reflectivity was tested in the same manner as in Example 1. The results are as follows: Figure 2 As shown, Figure 2 This is the infrared reflectivity test result diagram of the GaSb chip with anti-reflection film in comparative example 2 of the present invention. It can be seen from the results that the anti-reflection effect of the anti-reflection film in comparative example 2 is greatly weakened. Considering the actual production process, the design of the 8-group 16-layer film system requires the equipment to continuously evaporate 16 film layers. On the one hand, the monitoring error of the film thickness of each layer will gradually accumulate, so that the film thickness cannot meet the expected requirements. On the other hand, evaporating 16 film layers requires a larger production capacity of the equipment, which will consume more time and materials than the 4-group 8-layer of the present invention. And the more layers there are, the higher the requirements for the plating process, and as the number of layers increases, the absorption of the film also increases, and the physical properties also decrease greatly.

[0088] Comparative Example 3

[0089] A GaSb chip with an anti-reflection film is designed according to the structure shown in Table 3:

[0090] Table 3

[0091]

[0092] The chip was prepared and the infrared reflectivity was tested in the same manner as in Example 1. The results are as follows: Figure 3 As shown, Figure 3 This is a test result diagram of the infrared reflectivity of a GaSb chip provided with an anti-reflection film according to Comparative Example 3 of the present invention. From the results, it can be seen that the anti-reflection effect of the anti-reflection film of Comparative Example 3 is greatly weakened.

[0093] Comparative Example 4

[0094] A GaSb chip with an anti-reflection film is designed according to the structure shown in Table 4:

[0095] Table 4

[0096]

[0097] The chip was prepared and the infrared reflectivity was tested in the same manner as in Example 1. The results are as follows: Figure 4 As shown, Figure 4 This is a test result diagram of the infrared reflectivity of a GaSb chip provided with an anti-reflection film according to comparative example 4 of the present invention. From the results, it can be seen that the anti-reflection effect of the anti-reflection film of comparative example 4 is greatly weakened.

[0098] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. An anti-reflection film, characterized in that: include: An inner film layer, wherein the inner film layer is composed of ZnS and has a thickness of 900 nm to 1000 nm; A second film layer is disposed on the inner film layer, the second film layer is composed of YbF3, and the thickness of the second film layer is 1000 nm to 1100 nm; a third film layer disposed on the second film layer, the third film layer being composed of ZnS and having a thickness of 550 nm to 650 nm; A fourth film layer is disposed on the third film layer, the fourth film layer is composed of YbF3, and the thickness of the fourth film layer is 200 nm to 250 nm; A fifth film layer is disposed on the fourth film layer, the fifth film layer is composed of ZnS, and the thickness of the fifth film layer is 800 nm to 900 nm; A sixth film layer is disposed on the fifth film layer, the sixth film layer is composed of YbF3, and the thickness of the sixth film layer is 2600 nm to 2800 nm; a seventh film layer disposed on the sixth film layer, the seventh film layer being composed of ZnS, and having a thickness of 400 nm to 450 nm; An outer film layer is arranged on the seventh film layer, wherein the outer film layer is composed of YbF3 and has a thickness of 1500nm-1700nm.

2. The anti-reflection film according to claim 1, characterized in that: The thickness of the inner membrane layer is 950 nm to 1000 nm; The thickness of the second film layer is 1000 nm to 1050 nm; The thickness of the third film layer is 580 nm to 620 nm; The thickness of the fourth film layer is 200 nm to 220 nm; The thickness of the fifth film layer is 800 nm to 850 nm; The thickness of the sixth film layer is 2700 nm to 2800 nm; The thickness of the seventh film layer is 400 nm to 420 nm; The thickness of the outer membrane layer is 1600 nm to 1700 nm.

3. The anti-reflection film according to claim 2, characterized in that: The thickness of the inner membrane layer is 970.14 nm; The thickness of the second film layer is 1035.6 nm; The thickness of the third film layer is 600 nm; The thickness of the fourth film layer is 212.6 nm; The thickness of the fifth film layer is 821.56 nm; The thickness of the sixth film layer is 2772.96 nm; The thickness of the seventh film layer is 409.32 nm; The thickness of the outer membrane layer is 1638.61 nm.

4. The anti-reflection film according to any one of claims 1 to 3, characterized in that: The ZnS has a refractive index of 2.1-2.3 in the infrared band of 7.2 μm-9.5 μm.

5. The anti-reflection film according to any one of claims 1 to 3, characterized in that: The YbF3 has a refractive index of 1.4 to 1.

5.

6. A superlattice semiconductor chip, characterized in that: include: A superlattice semiconductor substrate and an anti-reflection film disposed on the superlattice semiconductor substrate; The anti-reflection film is the anti-reflection film according to any one of claims 1 to 5.

7. The superlattice semiconductor chip according to claim 6, characterized in that: The thickness of the superlattice semiconductor substrate is 0.8 μm-1.2 μm.

8. A GaSb chip, characterized in that: include: A GaSb substrate and an anti-reflection film disposed on the GaSb substrate; The anti-reflection film is the anti-reflection film according to any one of claims 1 to 5.

9. The GaSb chip according to claim 8, characterized in that: The thickness of the GaSb substrate is 0.8 μm to 1.2 μm.

10. A focal plane detector, characterized in that: The photosensitive element chip is the GaSb chip described in claim 8 or 9.

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