阅读说明：本技术 一种改善聚酰亚胺材料涂覆效果的工艺 (Process for improving coating effect of polyimide material ) 是由 孙会权 邢栗 张龙彪 孙元斌 于 2020-06-24 设计创作，主要内容包括：本发明公开了一种改善聚酰亚胺材料涂覆效果的工艺,属于半导体行业光刻技术领域。该方法步骤：(1)将晶圆送入涂胶单元,喷涂光阻稀释剂RRC,以增加光刻胶流动性；(2)使晶圆旋转,在晶圆表面形成一层RRC膜；(3)使光刻胶喷嘴喷涂光刻胶,喷涂光刻胶后,先使晶圆在转速V1时高速旋转T1时间,使晶圆上光刻胶铺展,该步骤决定了胶膜的厚度；然后降低晶圆转速至V2并旋转T2时间,使晶圆边缘光刻胶迅速回流；涂覆完后,晶圆边缘胶膜厚度均匀性良好；(4)晶圆传入热盘中进行烘烤,再经曝光、显影和冷盘冷却后,传回片盒。本发明在保证标准SPEC的前提下,提高了工艺质量,并减少了生产中的缺陷,在实际生产中实用效果显著。(The invention discloses a process for improving the coating effect of a polyimide material, and belongs to the technical field of photoetching in the semiconductor industry. The method comprises the following steps: (1) sending the wafer into a gluing unit, and spraying a light resistance diluent RRC to increase the mobility of the photoresist; (2) rotating the wafer to form a RRC film on the surface of the wafer; (3) spraying a photoresist on a photoresist nozzle, and after the photoresist is sprayed, firstly, rotating the wafer at a high speed for T1 time at a rotating speed of V1 to spread the photoresist on the wafer, wherein the thickness of the photoresist film is determined by the step; then, reducing the rotation speed of the wafer to V2 and rotating for T2 time to enable the photoresist on the edge of the wafer to rapidly reflow; after coating, the thickness uniformity of the glue film at the edge of the wafer is good; (4) the wafer is transferred into a hot plate for baking, and then is subjected to exposure, development and cooling by a cold plate and then is transferred back to the wafer box. The invention improves the process quality and reduces the defects in production on the premise of ensuring the standard SPEC, and has obvious practical effect in actual production.)

1. A process for improving the coating effect of a polyimide material is characterized by comprising the following steps: the method adopts a spin coating method to form a uniform photoresist layer on the surface of a wafer, and specifically comprises the following steps:

(1) sending the wafer into a gluing unit, and spraying a light resistance diluent RRC in a static state of the wafer to increase the mobility of the photoresist;

(2) moving the photoresist nozzle to the position right above the center of the wafer, and rotating the wafer to form an RRC film on the surface of the wafer;

(3) spraying a photoresist on a photoresist nozzle, and after the photoresist is sprayed, firstly, rotating the wafer at a high speed for T1 time at a rotating speed of V1 to spread the photoresist on the wafer, wherein the thickness of the photoresist film is determined by the step; then, reducing the rotation speed of the wafer to V2 and rotating for T2 time to enable the photoresist on the edge of the wafer to rapidly reflow; after coating, the thickness uniformity of the glue film at the edge of the wafer is good;

(4) and (4) transferring the wafer coated in the step (3) into a hot plate for baking, and finally transferring the wafer back to a wafer box after exposure, development and cooling of a cold plate.

2. The process for improving the coating effect of the polyimide material as claimed in claim 1, wherein: in the step (1), the gluing unit comprises a wafer bearing table and a CUP structure, the wafer is placed on the wafer bearing table, the CUP structure is a three-layer CUP structure, compared with the four-layer CUP structure, the wind flow in the wafer bearing table is changed, in the four-layer CUP structure, the upper edge of the third layer is 2.5-3.0mm away from the wafer bearing table from bottom to top, the horizontal height of the third layer is above the wafer bearing table, the upper edge of the second layer is counted from bottom to top in the three-layer CUP structure, the horizontal height is below the wafer bearing table and is 2.0-2.5mm away from the wafer bearing table, and therefore the gap between the wafer bearing table and the top layer CUP is enlarged, and the wind flow is enlarged.

3. The process for improving the coating effect of the polyimide material as claimed in claim 2, wherein: in the steps (1) - (3), the CUP air exhaust parameter is 2.0-6.0 kpa.

4. The process for improving the coating effect of the polyimide material as claimed in claim 1, wherein: in the step (2), the nozzle for spraying the photoresist adopts a tip nozzle (the original nozzle is optimized, the tip nozzle is adopted, the glue discharging state of the nozzle is better, and the uniformity of the film thickness can be improved).

5. The process for improving the coating effect of the polyimide material as claimed in claim 1, wherein: in the step (3), according to the requirement of the film thickness and the characteristics of PI, the rotation speed V1 is 4000rpm for 500-; meanwhile, the step acceleration should be 10000-30000r/s²T1 is 5-40s and T2 is 1-3 s.

6. The process for improving the coating effect of the polyimide material as claimed in claim 5, wherein: in the step (3), the smaller the rotation speed V2 is, the larger the reflux range is, and the setting is performed according to actual requirements.

7. The process for improving the coating effect of the polyimide material as claimed in claim 1, wherein: in the step (4), an exhaust pipe is arranged on the plate cover of the hot plate, the exhaust pipe is a large-aperture stainless steel square pipe, and the inner diameter of the exhaust pipe is 25-35 mm.

Technical Field

The invention relates to the technical field of semiconductor photoetching, in particular to a process for improving the coating effect of a polyimide material.

Background

Polyimide (PI) materials are widely used in the semiconductor field, particularly in the field of semiconductor device packaging. Polyimide relative to A1₂O₃And SiO₂Has a plurality of excellent performances, can effectively control the soft error and the signal delay of the chip, and can reduce the manufacturing cost and the like. Polyimide, polyimide resin composition and polyimide resin compositionThe typical applications of the multilayer interconnection metal circuit mainly comprise a primary passivation layer film or a secondary passivation layer film on the surface of a chip, a stress buffer layer film of a plastic package device, an interlayer dielectric insulating layer of a multilayer interconnection metal circuit and the like. Can be applied to various semiconductor devices such as memories, microprocessors, logic devices, power devices, ASICs, sensors, and the like.

In the field of semiconductors, a polyimide material is coated on the surface of a wafer through a glue coating developing machine, a glue coating nozzle is used for coating glue at the center of the wafer, and the polyimide material is uniformly coated on the surface of the wafer through high-speed rotation and other external environmental conditions.

Therefore, it is required to improve the polyimide coating process effectively, so as to improve the uniformity of the polyimide coating and increase the product yield.

Disclosure of Invention

The problems that the existing polyimide material coating process is poor in uniformity, more in subsequent process defects and low in process yield are solved; the invention aims to provide a process method for improving the coating effect of a polyimide PI material, which combines an optimized process formula structure with an optimized partial hardware structure, adds reasonable steps and selects proper process parameters in a conventional process formula, adds a slow speed step after a main speed step to enable the edge of the polyimide PI material to quickly flow back, reduces the edge thickness, combines the factors of improving CUP air exhaust, hot plate air exhaust and the like, improves the film thickness uniformity of the PI material, reduces the process cost and improves the process yield.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

a process for improving the coating effect of a polyimide material is to form a uniform photoresist layer on the surface of a wafer by a spin coating method, and specifically comprises the following steps:

(1) sending the wafer into a gluing unit, and spraying a light resistance diluent RRC in a static state of the wafer to increase the mobility of the photoresist;

(2) moving the photoresist nozzle to the position right above the center of the wafer, and rotating the wafer to form an RRC film on the surface of the wafer;

(3) spraying a photoresist on a photoresist nozzle, and after the photoresist is sprayed, firstly, rotating the wafer at a high speed for T1 time at a rotating speed of V1 to spread the photoresist on the wafer, wherein the thickness of the photoresist film is determined by the step; then, reducing the rotation speed of the wafer to V2 and rotating for T2 time to enable the photoresist on the edge of the wafer to rapidly reflow; after coating, the thickness uniformity of the glue film at the edge of the wafer is good;

(4) and (4) transferring the wafer coated in the step (3) into a hot plate for baking, and finally transferring the wafer back to a wafer box after exposure, development and cooling of a cold plate.

In the step (1), the gluing unit comprises a wafer bearing table and a CUP structure, the wafer is placed on the wafer bearing table, the CUP structure is a three-layer CUP structure, compared with the four-layer CUP structure, the wind flow in the wafer bearing table is changed, in the four-layer CUP structure, the upper edge of the third layer is 2.5-3.0mm away from the wafer bearing table from bottom to top, the horizontal height of the third layer is above the wafer bearing table, the upper edge of the second layer is counted from bottom to top in the three-layer CUP structure, the horizontal height is below the wafer bearing table and is 2.0-2.5mm away from the wafer bearing table, and therefore the gap between the wafer bearing table and the top layer CUP is enlarged, and the wind flow is enlarged.

In the steps (1) - (3), the CUP air exhaust parameter is 2.0-6.0 kpa.

In the step (2), the tip nozzle is adopted as the nozzle for spraying the photoresist (the original nozzle is optimized, the tip nozzle is adopted, the glue discharging state of the nozzle is better, and the uniformity of the film thickness can be improved).

In the step (3), the rotation speed V1 is 500-4000rpm, and the rotation speed V2 is 100-1000rpm according to the requirement of film thickness and the characteristic of PI; the rotating speed V2 is less than the rotating speed V1; meanwhile, the step acceleration should be 10000-30000r/s²(ii) a T1 is 5-40s, T2 is 1-3 s.

In the step (3), the smaller the rotation speed V2 is, the larger the reflux range is, and the reflux range can be set according to actual requirements.

In the step (4), an exhaust pipe is arranged on the plate cover of the hot plate, and the inner diameter of the exhaust pipe is 25-35 mm.

The invention has the advantages and beneficial effects that:

1. when the photoresist coating is carried out on the wafer, the conventional high-speed rotation is firstly carried out to lead the photoresist to be spread out in a rotating way, and then the wafer is slowly rotated for a period of time, thus leading the photoresist on the edge of the wafer to be quickly reflowed; by controlling the speed and time of the high-speed rotation and the slow-speed rotation, the problem of thick film at the edge of the wafer can be effectively solved.

2. The invention optimizes the CUP structure of the equipment used for gluing, the wafer edge in the optimized CUP structure is far away from the edges of the top layer and the inner layer CUP, the air exhaust amount can be effectively ensured, the CUP air exhaust value is set to a numerical value which can meet the process requirement, and the edge fluidity is enhanced and the uniformity is improved by controlling the air exhaust when the glue is coated in a rotating way.

3. The invention optimizes the exhaust pipe on the hot plate into a large-aperture stainless steel exhaust pipe, increases the inner diameter of the exhaust pipe to 25-30mm, and adjusts the exhaust volume through a speed regulating valve connected with the exhaust pipe. The air exhaust quantity above the wafer can be effectively guaranteed, the air exhaust value of the hot plate is set to be a numerical value capable of meeting the technological requirements, when the wafer is baked on the hot plate, evaporation of a solvent can be accelerated, and uniformity becomes good.

4. The invention has simple debugging, and after hardware transformation, in the subsequent production, the problem of uneven edge coating at present can be solved only by adjusting the process formula according to the actual requirement, thereby meeting the process requirement.

5. The invention realizes the uniform coating of the polyimide material, brings great convenience to the actual production and improves the yield of products.

Drawings

FIG. 1 is a schematic view of a heat coil exhaust duct; wherein: (a) existing small-caliber corrugated pipes; (b) the large-diameter stainless steel square pipe.

FIG. 2 is a prior art four-layer CUP structure;

FIG. 3 shows a three-layer CUP structure according to the present invention.

FIG. 4 is a view showing a nozzle structure used in the present invention.

Detailed Description

The invention is described in detail below with reference to the accompanying drawings and examples.

The invention provides a process for improving the coating effect of a polyimide PI material, which adopts a spin coating method to form a uniform photoresist layer on the surface of a wafer and specifically comprises the following steps:

(1) sending the wafer into a gluing unit, and spraying a light resistance diluent RRC in a static state of the wafer to increase the mobility of the photoresist;

(2) moving the photoresist nozzle to the position right above the center of the wafer, and rotating the wafer to form an RRC film on the surface of the wafer;

(3) spraying a photoresist on a photoresist nozzle, and after the photoresist is sprayed, firstly, rotating the wafer at a high speed for T1 time at a rotating speed of V1 to spread the photoresist on the wafer, wherein the thickness of the photoresist film is determined by the step; then, reducing the rotation speed of the wafer to V2 and rotating for T2 time to enable the photoresist on the edge of the wafer to rapidly reflow; after coating, the thickness uniformity of the glue film at the edge of the wafer is good;

(4) and (4) transferring the wafer coated in the step (3) into a hot plate for baking, and finally transferring the wafer back to a wafer box after exposure, development and cooling of a cold plate.

The gluing unit comprises a wafer bearing table and a CUP structure, a wafer is placed on the wafer bearing table, the CUP structure is a three-layer CUP structure, compared with the four-layer CUP structure (figure 3), the wind flow in the wafer bearing table is changed, in the four-layer CUP structure, the distance between the upper edge of a third layer from bottom to top and the wafer bearing table is 2.5-3.0mm, the horizontal height of the third layer is above the wafer bearing table, the upper edge of a second layer from bottom to top in the three-layer CUP structure is 2.0-2.5mm, the horizontal height is below the wafer bearing table, and therefore the gap between the wafer bearing table and the top-layer CUP is enlarged, and the wind flow is enlarged (figure 2).

The nozzle for spraying the photoresist in the process of the invention adopts a tip nozzle and a structure with a wide upper part and a narrow lower part (figure 4), so that the glue discharging state can be effectively improved, the phenomenon of uneven glue discharging of the original PFA plastic pipe nozzle is improved, and the outlet of the nozzle of the invention is more stable and uniform.

The cover of the hot plate is provided with an exhaust pipe, the exhaust of the cover of the hot plate is changed from the prior corrugated pipe with small pipe diameter (figure 1(a)) to the stainless steel square pipe with large pipe diameter (figure 1(b)), and the inner diameter of the exhaust pipe is 25-35 mm. The air exhaust pressure can be adjusted by matching with the front end adjusting valve of the unit; the air inlet flow of the hot plate cover is not arranged; the hot plate cover is added with a new heat function.