阅读说明：本技术 一种晶圆表面吸收式ir镀膜工艺 (Wafer surface absorption type IR coating process ) 是由 李涛 尚海 刘耀菊 王刚 于 2021-09-09 设计创作，主要内容包括：本发明提出了一种晶圆表面吸收式IR镀膜工艺,通过本工艺得到的产品使得可见光区(400nm～700nm)呈高透,近红外区(780nm～1100nm)呈高度截止状态,在不同角度光入射时光透过偏移量小,有助于改进角度偏移难题,解决了传统镀膜制程产品容易出现的图像失真、识别速度慢等问题,比起传统镀膜工艺只能保证光在0°-20°入射时光干扰小的窄角来讲,本工艺路线具有更优越的实用价值；晶圆表面经过电路及光路层结构加工后表面存在高度差,对旋涂要求较高,本发明工艺可较好的去除凹槽中的油墨残留,且光路层表面油墨分布较均匀,膜厚散差控制在0.2μm左右。(The invention provides a wafer surface absorption type IR (infrared) coating process, a product obtained by the process ensures that a visible light area (400 nm-700 nm) is high-transmittance, a near infrared area (780 nm-1100 nm) is in a high-cutoff state, the light transmittance offset is small when light is incident at different angles, the problem of angle offset is improved, the problems of image distortion, low recognition speed and the like easily caused by the traditional coating process product are solved, and compared with the traditional coating process, the process route has more excellent practical value when only ensuring that the light is in a narrow angle with small light interference when the light is incident at 0-20 degrees; the surface of the wafer is processed by the circuit and light path layer structure, the height difference exists on the surface, the requirement on spin coating is higher, the process can better remove the ink residue in the groove, the ink distribution on the surface of the light path layer is more uniform, and the film thickness dispersion difference is controlled to be about 0.2 mu m.)

1. A wafer surface absorption type IR coating process is characterized by comprising the following steps:

s1, cleaning: cleaning the surface of the wafer, removing particles and chemical residues on the surface of the wafer, and drying the cleaned wafer by spin;

s2, spin-on ink: dropping 2.5ml of ink into the center of the wafer by a dispensing module of a spin coater, continuously injecting the ink in a trickle flow state at a speed of 3.0ml/min by a Teflon needle at this stage, rotating the wafer at an initial low speed of 800rpm for 3s, and then 785rad/s²The angular acceleration is increased for 0.4s, when the rotation speed is increased to 3800rpm, the rotation speed is maintained for 5s, and then 104.67rad/s is used²The angular acceleration is reduced for 3.8s, the accumulated spin-coating time is 12.2s in total, and an ink film layer is formed;

s3, baking: according to the characteristics of the ink, baking at 145 ℃ for 80min after coating is finished, and keeping the environment of an oven to eliminate the oxidation atmosphere when baking at high temperature;

s4, coating P-type protective glue: coating a P-type protective adhesive on the surface of the ink film layer of the baked wafer, and depositing a P-type protective adhesive film layer with the thickness of 1 mu m;

s5, MP protective glue coating: MP protective glue is coated on the front surface of a needle head 1cm above a wafer, after the glue coating is finished, the base is driven by the wafer to rotate concentrically through vacuum adsorption, and a 10 mu mMP protective glue film layer is formed through deposition;

s6, lithography development rinse: arranging a mask plate above the wafer, and carrying out photoetching development, wherein the exposure energy is 200mJ/cm²Soaking the developing solution for 300s, then washing, and spin-drying the residual cleaning solution by washing for 30s and SRD;

s7, dry etching and removing photoresist: etching the non-light-blocking part of the P-type protective glue without the MP protective glue and the ink film layer by adopting plasma which generates charged particles and neutral atoms, molecules and free radicals with high chemical activity through dry etching to separate the surface of the wafer from the surface of the P-type protective glue without the MP protective glue, placing the product into degumming liquid at 85 ℃, degumming for 1h and removing the MP protective glue film layer;

s8, gluing the PR glue layer: PR glue is coated on the front surface of a needle head 1cm above a wafer, after the glue coating is finished, the base is driven by the wafer to rotate concentrically through vacuum adsorption, and a 10-micron PR glue layer is formed through deposition;

s9, PR resist lithography development: a mask plate corresponding to the MP protective glue is arranged above the wafer for photoetching development, wherein the exposure energy is 400mJ/cm^2，Soaking the developing solution for 480s, then washing, and spin-drying the residual cleaning liquid by washing for 30s and SRD;

s10, evaporation of IR coating: performing IR coating in a form of evaporation coating to form an IRC layer with the thickness of 5.6 microns;

s11, removing photoresist and cleaning: after the evaporation coating is finished, the product is placed into a degumming solution heated to 85 ℃ for degumming for 2h, a PR layer is stripped, and then the whole process is finished by washing with QDR and drying by SRD.

2. The wafer surface absorption type IR coating process according to claim 1, wherein in step s1, the wafer surface is cleaned by QDR cleaning, QDR water injection time is 50s, water discharge time is 8s, times are 2, cleaning time is 2min in total, then SRD drying is carried out, the process is carried out at 1200rpm/4min and 1600rpm/6min, and total time is 10 min.

3. The process of claim 1, wherein in step s3, the baking oven is kept under a nitrogen or argon atmosphere to remove the oxidation atmosphere during the high temperature baking.

4. The process of claim 1, wherein in step s4, the P-type protective glue is applied by spraying and then spin-coating at 3000 rpm.

5. The process of claim 1, wherein the step s10, the step of evaporating IR coating includes a cleaning step, SiO coating₂Deposition step and TiO₂Deposition step, cleaning step, SiO₂Deposition step and TiO₂The ion source parameters of the deposition step were:

a cleaning step: ion source voltage 750V, current 750mA, electron gun voltage 600V, neutralizer and ion source oxygen 75sccm, ion source argon 0sccm, neutralizer argon 8 sccm;

SiO₂a deposition step: ion source voltage 1250V, current 1250mA, electron gun voltage 800V, neutralizer and ion source oxygen 40sccm, ion source argon 0sccm, neutralizer argon 8 sccm;

TiO₂a deposition step: ion source voltage 1550V, current 1450mA, electron gun voltage 850V, neutralizer and ion source oxygen 70sccm, ion source argon 10sccm, neutralizer argon 10 sccm.

Technical Field

The invention relates to the field of optical identification, in particular to a wafer surface absorption type IR coating process.

Background

The original IR (absorbed reflective) coating process for the wafer surface comprises the following steps: the method comprises the steps of gluing, photoetching, coating, developing and degumming, and an IR-CUT (Infarared Ray-CUT infrared cutoff) film, an IRC layer for short, is produced by the process route, when the incident angle of light is gradually increased from 0 degrees, sunlight, lamplight, diffusely reflected ambient light and the like can be interference sources, the larger the incident angle is, the larger the deviation of the light penetrating through a product film layer is, serious light interference exists when the incident angle exceeds 20 degrees, the wave bands of the light of the interference sources are very wide, some of the interference sources exceed 1100nm invisible light regions, and the high-intensity interference can cause the problems of low recognition speed, narrow detection range, low accuracy and the like, so that the image recognition quality is influenced.

Namely, the original wafer surface IR coating process mainly has two problems: (1) the interference light influences the image recognition; (2) the deviation angle of the incident light transmission route is larger.

Disclosure of Invention

In order to solve the technical problem, the invention designs an absorption type IR coating process for the surface of a wafer.

The invention adopts the following technical scheme:

an absorption-type IR coating process for wafer surface comprises the following steps:

s1, cleaning: cleaning the surface of the wafer, removing particles and chemical residues on the surface of the wafer, and drying the cleaned wafer by spin;

s2, spin-on ink: dropping 2.5ml of ink into the center of the wafer by a dispensing module of a spin coater, continuously injecting the ink in a trickle flow state at a speed of 3.0ml/min by a Teflon needle at this stage, rotating the wafer at an initial low speed of 800rpm for 3s, and then 785rad/s²The angular acceleration is increased for 0.4s, when the rotation speed is increased to 3800rpm, the rotation speed is maintained for 5s, and then 104.67rad/s is used²The angular acceleration is reduced for 3.8s, the accumulated spin-coating time is 12.2s in total, and an ink film layer is formed;

s3, baking: according to the characteristics of the ink, baking at 145 ℃ for 80min after coating is finished, and keeping the environment of an oven to eliminate the oxidation atmosphere when baking at high temperature;

s4, coating P-type protective glue: coating a P-type protective adhesive on the surface of the ink film layer of the baked wafer, and depositing a P-type protective adhesive film layer with the thickness of 1 mu m;

s5, MP protective glue coating: MP protective glue is coated on the front surface of a needle head 1cm above a wafer, after the glue coating is finished, the base is driven by the wafer to rotate concentrically through vacuum adsorption, and a 10 mu mMP protective glue film layer is formed through deposition;

s6, lithography development rinse: arranging a mask plate above the wafer, and carrying out photoetching development, wherein the exposure energy is 200mJ/cm²Soaking the developing solution for 300s, then washing, and spin-drying the residual cleaning solution by washing for 30s and SRD;

s7, dry etching and removing photoresist: etching the non-light-blocking part of the P-type protective glue without the MP protective glue and the ink film layer by adopting plasma which generates charged particles and neutral atoms, molecules and free radicals with high chemical activity through dry etching to separate the surface of the wafer from the surface of the P-type protective glue without the MP protective glue, placing the product into degumming liquid at 85 ℃, degumming for 1h and removing the MP protective glue film layer; the charged particles include ions, electrons, and the like.

s8, gluing the PR glue layer: PR glue is coated on the front surface of a needle head 1cm above a wafer, after the glue coating is finished, the base is driven by the wafer to rotate concentrically through vacuum adsorption, and a 10-micron PR glue layer is formed through deposition;

s9, PR resist lithography development: by arranging a mask plate corresponding to the MP protective adhesivePerforming photoetching development on the wafer, wherein the exposure energy is 400mJ/cm^2，Soaking the developing solution for 480s, then washing, and spin-drying the residual cleaning liquid by washing for 30s and SRD;

s10, evaporation of IR coating: performing IR coating in a form of evaporation coating to form an IRC layer with the thickness of 5.6 microns;

s11, removing photoresist and cleaning: after the evaporation coating is finished, the product is placed into a degumming solution heated to 85 ℃ for degumming for 2h, a PR layer is stripped, and then the product is cleaned by a QDR (quick discharge spray rinsing tank) and is dried by an SRD (spin drying) to finish the whole process.

Preferably, in step s1, the surface of the wafer is cleaned by QDR, the QDR water injection time is 50s, the water drainage time is 8s, the times are 2 times, the cleaning time is 2min in total, and then the wafer is dried by SRD, wherein the rotating speed in the process is 1200rpm/4min and 1600rpm/6min, and the total time is 10 min.

Preferably, in step s3, during the high temperature baking, the oven environment is kept to exclude the oxidation atmosphere by flushing nitrogen or argon. The baking is to make the ink deposition layer firmer and not easy to have the problems of film cracking, film stripping and the like.

Preferably, in step s4, the P-type protective paste is applied by spin coating after spray coating, wherein the spin coating speed is 3000 rpm. The P-type protective adhesive has two functions, one function is to protect the ink layer from falling off and being damaged, so that a good functional use environment is created for the ink layer, the other function is to connect the coating layer and the IRC layer, the combination firmness of the IRC coating layer and the P-type protective adhesive is better, and the problems of film layer separation, air entering, doping and the like caused by weak binding force of the ink and the IRC layer can be avoided. The ink layer and the P-type protective adhesive layer are both functional film layers, and the MP protective adhesive layer is a protective functional film layer.

Preferably, in step s10, the step of evaporating the IR coating includes a cleaning step, SiO₂Deposition step and TiO₂Deposition step, cleaning step, SiO₂Deposition step and TiO₂The ion source parameters of the deposition step were:

a cleaning step: ion source voltage 750V, current 750mA, electron gun voltage 600V, neutralizer and ion source oxygen 75sccm, ion source argon 0sccm, neutralizer argon 8 sccm;

SiO₂a deposition step: ion source voltage 1250V, current 1250mA, electron gun voltage 800V, neutralizer and ion source oxygen 40sccm, ion source argon 0sccm, neutralizer argon 8 sccm;

TiO₂a deposition step: ion source voltage 1550V, current 1450mA, electron gun voltage 850V, neutralizer and ion source oxygen 70sccm, ion source argon 10sccm, neutralizer argon 10 sccm.

The invention has the beneficial effects that: (1) the invention provides a wafer surface absorption type IR (infrared) coating process, a product obtained by the process ensures that a visible light area (400 nm-700 nm) is high-transmittance, a near infrared area (780 nm-1100 nm) is in a high-cutoff state, the light transmittance offset is small when light is incident at different angles, the problem of angle offset is improved, the problems of image distortion, low recognition speed and the like easily caused by the product of the traditional coating process are solved, and compared with the narrow angle which is only ensured by the traditional coating process and has small light interference when the light is incident at 0-20 degrees, the process route has more excellent practical value; (2) the surface of the wafer is processed by the circuit and light path layer structure, the height difference exists on the surface, the requirement on spin coating is high, the process can well remove the ink residue in the groove, the ink distribution on the surface of the light path layer is uniform, and the film thickness dispersion difference is controlled to be about 0.2 mu m.

Drawings

FIG. 1 is a process flow diagram of the present invention;

FIG. 2 is a flow chart of a process product structure formation of the present invention;

FIG. 3 is a comparison of spectra transmitted through the present invention and a prior IR coated product;

Detailed Description

The technical scheme of the invention is further described in detail by the following specific embodiments in combination with the attached drawings:

example (b): as shown in the attached fig. 1 and 2, a wafer surface absorption type IR coating process comprises the following steps:

s1, cleaning: cleaning the surface of the wafer, removing particles and chemical residues on the surface of the wafer, and drying the cleaned wafer by spin;

s2, spin-on ink: dropping 2.5ml of ink into the center of the wafer by a dispensing module of a spin coater, continuously injecting the ink in a trickle flow state at a speed of 3.0ml/min by a Teflon needle at this stage, rotating the wafer at an initial low speed of 800rpm for 3s, and then 785rad/s²The angular acceleration is increased for 0.4s, when the rotation speed is increased to 3800rpm, the rotation speed is maintained for 5s, and then 104.67rad/s is used²The angular acceleration is reduced for 3.8s, the accumulated spin-coating time is 12.2s in total, and an ink film layer is formed;

s3, baking: according to the characteristics of the ink, baking at 145 ℃ for 80min after coating is finished, and keeping the environment of an oven to eliminate the oxidation atmosphere when baking at high temperature;

s4, coating P-type protective glue: coating a P-type protective adhesive on the surface of the ink film layer of the baked wafer, and depositing a P-type protective adhesive film layer with the thickness of 1 mu m;

s5, MP protective glue coating: MP protective glue is coated on the front surface of a needle head 1cm above a wafer, after the glue coating is finished, the base is driven by the wafer to rotate concentrically through vacuum adsorption, and a 10 mu mMP protective glue film layer is formed through deposition;

s6, lithography development rinse: arranging a mask plate above the wafer, and carrying out photoetching development, wherein the exposure energy is 200mJ/cm²Soaking the developing solution for 300s, then washing, and spin-drying the residual cleaning solution by washing for 30s and SRD;

s7, dry etching and removing photoresist: etching the non-light-blocking part of the P-type protective glue without the MP protective glue and the ink film layer by adopting plasma which generates charged particles and neutral atoms, molecules and free radicals with high chemical activity through dry etching to separate the surface of the wafer from the surface of the P-type protective glue without the MP protective glue, placing the product into degumming liquid at 85 ℃, degumming for 1h and removing the MP protective glue film layer; the charged particles include ions, electrons, and the like.

s8, gluing the PR glue layer: PR glue is coated on the front surface of a needle head 1cm above a wafer, after the glue coating is finished, the base is driven by the wafer to rotate concentrically through vacuum adsorption, and a 10-micron PR glue layer is formed through deposition;

s9, PR resist lithography development: a mask plate corresponding to the MP protective adhesive is arranged on the waferCarrying out photoetching development, wherein the exposure energy is 400mJ/cm^2，Soaking the developing solution for 480s, then washing, and spin-drying the residual cleaning liquid by washing for 30s and SRD;

s10, evaporation of IR coating: performing IR coating in a form of evaporation coating to form an IRC layer with the thickness of 5.6 microns;

s11, removing photoresist and cleaning: after the evaporation coating is finished, the product is placed into a degumming solution heated to 85 ℃ for degumming for 2h, a PR layer is stripped, and then the product is cleaned by a QDR (quick discharge spray rinsing tank) and is dried by an SRD (spin drying) to finish the whole process.

In step s1, the surface of the wafer is cleaned through QDR, the QDR water injection time is 50s, the water drainage time is 8s, the times are 2 times, the total cleaning time is 2min, then the wafer is dried through SRD, the rotating speed in the process is dried through two steps of 1200rpm/4min and 1600rpm/6min, and the total time is 10 min.

In step s3, during high temperature baking, the oven environment is kept to be free of oxidation atmosphere by flushing nitrogen or argon. The baking is to make the ink deposition layer firmer and not easy to have the problems of film cracking, film stripping and the like.

In step s4, the P-type protective glue is coated by spin coating after spray coating, wherein the spin coating speed is 3000 rpm. The P-type protective adhesive has two functions, one function is to protect the ink layer from falling off and being damaged, so that a good functional use environment is created for the ink layer, the other function is to connect the coating layer and the IRC layer, the combination firmness of the IRC coating layer and the P-type protective adhesive is better, and the problems of film layer separation, air entering, doping and the like caused by weak binding force of the ink and the IRC layer can be avoided. The ink layer and the P-type protective adhesive layer are both functional film layers, and the MP protective adhesive layer is a protective functional film layer.

In step s10, evaporating the IR coating includes a cleaning step, SiO₂Deposition step and TiO₂Deposition step, cleaning step, SiO₂Deposition step and TiO₂The ion source parameters of the deposition step were:

a cleaning step: ion source voltage 750V, current 750mA, electron gun voltage 600V, neutralizer and ion source oxygen 75sccm, ion source argon 0sccm, neutralizer argon 8 sccm;

SiO₂a deposition step: ion source voltage 1250V, current 1250mA, electron gun voltage 800V, neutralizer and ion source oxygen 40sccm, ion source argon 0sccm, neutralizer argon 8 sccm;

TiO₂a deposition step: ion source voltage 1550V, current 1450mA, electron gun voltage 850V, neutralizer and ion source oxygen 70sccm, ion source argon 10sccm, neutralizer argon 10 sccm.

As shown in fig. 3, a comparison graph of spectra transmitted through the present invention and the existing IR coated product is shown, in which the ordinate is transmittance, the abscissa is wavelength, 1 is a spectral curve generated by passing through the existing ordinary film at an angle of 0 degrees, 2 is a spectral curve generated by passing through the film of the existing IR coated product of the present invention at an angle of 0 degrees, 3 is a spectral curve generated by passing through the existing ordinary film at an angle of 30 degrees, and 4 is a spectral curve generated by passing through the film of the existing IR coated product at an angle of 30 degrees, it can be seen that the existing ordinary coating shifts around 30nm in the range of 0-30 degrees at the IR half value (transmittance T = 50%), and shifts around 1nm in the range of 0-30 degrees at the IR half value (T = 50%) of the film of the present invention, which effectively reduces light interference in a wide-angle field.

The above-described embodiments are only preferred embodiments of the present invention, and are not intended to limit the present invention in any way, and other variations and modifications may be made without departing from the spirit of the invention as set forth in the claims.