Optical coating semiconductor wafer grafting method and optical coating semiconductor

Abstract

The present invention provides an optically coated semiconductor wafer grafting method and an optically coated semiconductor. The method is to coat a photoresist on the surface of a semiconductor wafer substrate and divide the surface of the semiconductor wafer substrate into a light-transmitting area and a light-shielding area, then use a photolithography process to carve a pattern in the light-transmitting area and then deposit an optical thin film, and alternately stack optical thin film layers of high refractive index or low refractive index materials on the surface of the light-transmitting area, so that the film layer thickness gradient at the junction of the light-transmitting area and the light-shielding area changes, and finally remove the photoresist. In the vertical direction, the edge of the IRC layer away from the substrate does not overlap with the edge of the adhesive backing surface of the optically coated semiconductor obtained by the method, and optical performance is added while ensuring its normal electrical performance. The added optical performance greatly improves the product precision and has a high promotion value.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor wafer chips, and in particular to an optically coated semiconductor wafer grafting method and an optically coated semiconductor. Background Art

[0002] At present, most electronic products on the market are using semiconductor chips made of single crystal silicon. The main production method is to etch and wire on semiconductor wafers to make semiconductor wafer devices that can achieve certain functions. Biometric devices are developing rapidly as an emerging industry. The chips used are semiconductor chips. Semiconductor chips use their own electrical properties to achieve biometrics. However, if semiconductor chips are only used as biometric chips, there is a common problem of low biometric recognition, which affects the use effect. Summary of the invention

[0003] In order to solve the above technical problems, the present invention designs an optically coated semiconductor wafer grafting method and an optically coated semiconductor. Based on the above background, this research and development combines the optical film with the semiconductor wafer using the photolithography process, deposits the optical film on the original semiconductor wafer, and adds optical properties while ensuring its normal electrical properties, thereby achieving the purpose of improving product precision.

[0004] The present invention adopts the following technical scheme: a method for grafting an optically coated semiconductor wafer, which comprises: (1) coating a photoresist on the surface of a semiconductor wafer substrate; (2) dividing the surface of the semiconductor wafer substrate into a light-transmitting area and a light-shielding area; (3) protecting the light-shielding area with a photoresist, and using a photolithography process to carve a pattern in the light-transmitting area; (4) depositing an optical thin film after the photolithography process is completed, and stacking optical thin film layers of high refractive index or low refractive index materials on the surface of the light-transmitting area in an alternating manner, wherein the thickness of the film layer at the interface between the light-transmitting area and the light-shielding area changes gradually; and (5) removing the photoresist.

[0005] Preferably, the film thickness changes gradually in the range of 1.5-3.5 um at the junction of the light-transmitting area and the light-shielding area.

[0006] Preferably, in step (4), the stack is such that the first optical thin film layer stacked on the surface of the light-transmitting area is a low-refractive-index film layer, and the second optical thin film layer is a high-refractive-index film layer.

[0007] Preferably, in step (4), the stack is such that the first optical thin film layer stacked on the surface of the light-transmitting area is a high refractive index film layer, and the second optical thin film layer is a low refractive index film layer.

[0008] Preferably, the refractive index of the low refractive index film layer is 1.4-1.55, and the refractive index of the high refractive index film layer is 2-4.5.

[0009] Preferably, in step (4), the total number of layers of the stack is 2-60 layers.

[0010] Preferably, in step (3), the pattern is a square.

[0011] Preferably, in step (4), the outermost surface of the optical film is silicon dioxide.

[0012] As another aspect of the present invention, the present invention provides an optically coated semiconductor, characterized in that: in the vertical direction, the edge of the IRC layer away from the substrate does not overlap with the edge of the adhesive-coated backing surface.

[0013] The beneficial effects of the present invention are:

[0014] The present invention deposits an optical film on a semiconductor wafer element, and adds optical performance while ensuring its normal electrical performance. The added optical performance greatly improves the product precision.

[0015] Compared with the traditional coating production process, the present invention also has the following advantages:

[0016] 1. Quantity advantage: In the previous coating production process, only one piece can be made at a time. The method of the present invention can increase the output. The quantity varies according to the size and the coating equipment. For example, a 12-inch product can be coated with 12 pieces at a time.

[0017] 2. Thickness uniformity advantage: The previous coating method was not uniform enough, with a range of 80nm, and poor uniformity, which would affect the change of the spectral waveform and the transmittance of the product. The method of the present invention can make the film layer more uniform, and the range can be controlled within 5nm.

[0018] 3. Efficiency advantage: Due to the characteristics of ink, the spectral characteristics of coating cannot be changed at will, while the coating curve of the present invention can be changed in time according to customer requirements, and the time arrangement efficiency is higher. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of a film structure of a product processed by the process of the present invention;

[0020] Figure 2 It is a schematic diagram of mass production of the product processed by the process of the present invention;

[0021] Figure 3 It is a microscopic scan of the optical thin film layer of the product processed by the process of the present invention;

[0022] Figure 4 It is a test reliability diagram of sample No. 2 of the product processed by the process of the present invention and a film thickness measurement diagram above IRC;

[0023] Figure 5 It is a data drop detection diagram of the optical thin film layer of the product processed by the process of the present invention; DETAILED DESCRIPTION

[0024] The technical solution of the present invention is further described in detail below through specific embodiments and in conjunction with the accompanying drawings:

[0025] The operating equipment of the present invention includes: a photolithography machine, a coating machine, an exposure machine, and a developing machine.

[0026] Finished product inspection method: The high-temperature storage inspection experiment requires storage at 125°C for 1000 hours and observation every 500 hours; the low-temperature storage inspection experiment requires storage at -40°C for 500 hours and observation every 250 hours; the constant temperature and humidity inspection experiment requires storage at 85°C / 85%RH for 1000 hours and observation every 500 hours; the temperature shock inspection experiment requires cyclic shock at a temperature of -40°C to 85°C, with each cycle lasting 30 minutes, and 1000 cycles must be completed, with observation every 500 cycles; the PCT inspection experiment requires standing for 18 hours at a temperature of 121°C, a humidity of 100%RH, and a pressure of 2Mpa.

[0027] Example 1

[0028] As attached Figure 1 As shown, an optical coating semiconductor wafer grafting technology process, the process steps are:

[0029] 1. Select a 12-inch silicon semiconductor wafer;

[0030] 2. Dividing the surface of the semiconductor wafer substrate into a light-transmitting area and a light-shielding area;

[0031] 3. Use the spin coating process to evenly coat the photoresist on the light-shielding area on the surface of the semiconductor wafer. The light-shielding area that does not need to be combined with the optical film will be protected. When coating, an inverted trapezoid or a regular trapezoid will be formed at the junction of the light-shielding area and the light-transmitting area. In the subsequent process, the light-transmitting area and the light-shielding area can be accurately distinguished by the coating and development of the photolithography machine. Through research, it is found that the inverted trapezoid or regular trapezoid formed at the junction of the light-shielding area and the light-transmitting area, the steeper the trapezoidal hypotenuse, the better. If the slope of the trapezoid is too small (when the ratio of the height of the slope to its width is less than 1:1.5, it is too small), it will cause data drops in this area, affecting the recognition effect.

[0032] 4. Use photolithography to make a corresponding pattern on the transparent area of ​​the substrate surface of the semiconductor wafer. The pattern has a regular shape, preferably a square, such as Figure 2 It can be seen that the size accuracy of the optical thin film layer pattern has reached 0.3um;

[0033] 5. After the photolithography process is completed, the optical thin film is deposited by the evaporation process, and the optical thin film layers of high refractive index and low refractive index materials are alternately stacked on the surface of the unprotected light-transmitting area of ​​the semiconductor wafer, and firmly bonded to the semiconductor wafer; the refractive index of the film layer of the low refractive index material is 1.4-1.55, and the refractive index of the film layer of the high refractive index material is 2-4.5. The total number of deposited optical thin film layers is 2-60 layers.

[0034] For the sake of convenience of description, after the optical thin film is deposited on the semiconductor wafer substrate, the contact surface between the first layer of thin film and the semiconductor wafer substrate is called the adhesive backing surface.

[0035] 6. Use etching process to remove the photoresist in the light-shielding area to obtain the finished product, such as Figure 3 The top picture shows the completion of the entire optically coated semiconductor wafer grafting.

[0036] In step 5, the first optical thin film layer is a film layer of a low refractive index material, and the second optical thin film layer is a film layer of a high refractive index material, and the optical thin film deposited in this staggered stacking should achieve the effect of visible light transmission and infrared light cutoff; in step 5, a layer of silicon dioxide is attached to the outermost surface of the optical thin film. The low and high refractive index material layers can be selected from Ti3O5-SiO2, Nb2O5, Ta2O5, TiO2, ZrO2, HfO2, Ti3O5-SiO2, Nb2O5, and Ta2O5.

[0037] Taking the square as an example, the finished product is prepared using the above steps according to the following surface film layer scheme, as follows:

[0038]

[0039] After the finished product is obtained, it is subjected to high temperature storage, low temperature storage, constant temperature and humidity, temperature shock and PCT testing experiments in turn to observe whether the finished product is de-molded or cracked, and to determine whether the final qualified finished product is obtained. After testing, the yield of the method of the present invention is 98%-98.78%, which meets the yield target requirements. The constant temperature and humidity test shows that the surface of the sample after the test is dirty and difficult to wipe (see Figure 4 ), the test piece was sliced ​​to measure the film thickness at the dirty and non-dirty positions, and it was found that the dirt was only attached during the reliability test process, and the film thickness of the product itself did not change, and there was no abnormality such as shedding, cracking, delamination, and foaming. The rest of the test results also showed that the samples did not show abnormalities such as shedding, cracking, delamination, and foaming.

[0040] During the research process, the applicant discovered that there was an L-shaped edge data drop between the adhesive backing surface and the first film layer (such as the IRC layer). The reason for the data drop in this area was that the slope of the inverted trapezoid or the right trapezoid formed during the adhesive coating was large. After testing, the ratio of the height of the trapezoid formed during the adhesive coating of sample No. 1 and sample No. 2 to its width was 1.45:1.65 and 1.5:1.55 respectively, which was close to 1:1. The adhesive shape was maintained well and data drop basically did not occur. However, only when the edge of the IRC layer away from the substrate overlapped with the edge of the adhesive backing surface in the vertical direction, serious edge drop would occur, resulting in abnormal product detection (see Figure 5 ).

[0041] The above-described embodiment is only a preferred solution of the present invention and does not limit the present invention in any form. There are other variations and modifications without exceeding the technical solution described in the claims.

Claims

1. A method for grafting optically coated semiconductor wafers, characterized in that: include, (1) coating a photoresist on a surface of a semiconductor wafer substrate; (2) dividing the surface of the semiconductor wafer substrate into a light-transmitting area and a light-shielding area; (3) protecting the light-shielding area with a photoresist and engraving a pattern in the light-transmitting area using a photolithography process; (4) After the photolithography process is completed, an optical thin film is deposited, and optical thin film layers of high refractive index and low refractive index materials are alternately stacked on the surface of the light-transmitting area. The film thickness gradient changes in the range of 1.5-3.5 um at the junction of the light-transmitting area and the light-shielding area. The ratio of the height of the trapezoid formed during glue coating to its width is 1.45:1.65 or 1.5:1.55, and the edge of the IRC layer away from the substrate in the vertical direction does not overlap with the edge of the glue-coated backing surface; (5) removing the photoresist; The optically coated semiconductor wafer is used for biometric identification.

2. The optically coated semiconductor wafer grafting method according to claim 1, characterized in that: In step (4), the first optical thin film layer stacked on the surface of the light-transmitting area is a low-refractive-index film layer, and the second optical thin film layer is a high-refractive-index film layer.

3. The optically coated semiconductor wafer grafting method according to claim 1, characterized in that: In step (4), the first optical thin film layer stacked on the surface of the light-transmitting area is a high-refractive-index film layer, and the second optical thin film layer is a low-refractive-index film layer.

4. The optically coated semiconductor wafer grafting method according to claim 3, characterized in that: The refractive index of the low refractive index film layer is 1.4-1.55, and the refractive index of the high refractive index film layer is 2-4.

5.

5. The optically coated semiconductor wafer grafting method according to claim 1, characterized in that: In step (4), the total number of layers of the stack is 2-60 layers.

6. The optically coated semiconductor wafer grafting method according to claim 1, characterized in that: In step (3), the pattern is a square.

7. The optically coated semiconductor wafer grafting method according to claim 1, characterized in that: In step (4), the outermost surface of the optical film is silicon dioxide.

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