阅读说明：本技术 一种降低晶圆片损伤层厚度偏差值的腐蚀工艺 (Corrosion process for reducing thickness deviation value of damaged layer of wafer ) 是由 刘姣龙 刘建伟 刘园 武卫 由佰玲 裴坤羽 孙晨光 王彦君 祝斌 常雪岩 杨春雪 于 2021-01-07 设计创作，主要内容包括：本发明提供一种降低晶圆片损伤层厚度偏差值的腐蚀工艺,步骤包括：执行将若干晶圆片同步进入药液内并稳定放置,且所有所述晶圆片的V型槽均朝同一方向设置；控制所述晶圆片在所述药液内以设定转速同步旋转(N+0.5)圈,N为大于1的整数；再提取所述晶圆片离开药液；其中,所述晶圆片从进入所述药液至稳定放置所用时间与所述晶圆片从静置完成后到完全被提取离开所述药液所用时间相同。本发明可使晶圆片进而保证先进入槽体中药液的部位先离开药液,最大限度地缩小晶圆片双面腐蚀厚度的差值,提高晶圆片腐蚀厚度的均匀性和一致性,从而为后续抛光加工获得合格的几何参数奠定基础,提高生产效率。(The invention provides a corrosion process for reducing thickness deviation value of a damaged layer of a wafer, which comprises the following steps: synchronously feeding a plurality of wafers into the liquid medicine and stably placing the wafers, wherein the V-shaped grooves of all the wafers are arranged towards the same direction; controlling the wafer to synchronously rotate (N +0.5) circles in the liquid medicine at a set rotating speed, wherein N is an integer greater than 1; extracting the wafer and leaving the liquid medicine; wherein the time from the wafer entering the liquid medicine to the stable standing is the same as the time from the wafer standing to the wafer being completely extracted and leaving the liquid medicine. The invention can ensure that the part of the wafer, which is firstly put into the tank and is filled with the liquid medicine, is firstly separated from the liquid medicine, so as to reduce the difference of the double-sided corrosion thickness of the wafer to the maximum extent and improve the uniformity and consistency of the corrosion thickness of the wafer, thereby laying a foundation for obtaining qualified geometric parameters for subsequent polishing processing and improving the production efficiency.)

1. The corrosion process for reducing the thickness deviation value of the damaged layer of the wafer is characterized by comprising the following steps of: synchronously feeding a plurality of wafers into the liquid medicine and stably placing the wafers, wherein the V-shaped grooves of all the wafers are arranged towards the same direction;

controlling the wafer to synchronously rotate (N +0.5) circles in the liquid medicine at a set rotating speed, wherein N is an integer greater than 1;

extracting the wafer and leaving the liquid medicine;

wherein the time from the wafer entering the liquid medicine to the stable standing is the same as the time from the wafer standing to the wafer being completely extracted and leaving the liquid medicine.

2. The etching process for reducing the thickness deviation value of the damaged layer of the wafer as claimed in claim 1, wherein when the wafer enters the chemical solution, the V-shaped grooves of the wafer are all vertically arranged upward; and after the wafer rotates and stands, the V-shaped grooves are vertically arranged downwards until the wafer is taken out.

3. The etching process as claimed in claim 1 or 2, wherein the time taken for the wafer to remain stable after entering the chemical solution is 8-10 s.

4. The etching process as set forth in claim 3, wherein the wafer is rotated in a clockwise direction at a constant rotation speed.

5. The etching process as set forth in claim 4, wherein the time taken for the wafer to rotate is 80-100 s.

6. The etching process for reducing the thickness deviation of the damaged layer of the wafer as set forth in any one of claims 1-2, 4 and 5, wherein the chemical solution is pure potassium hydroxide solution with a mass concentration of 42-48%; preferably, its mass concentration is 45%.

7. The etching process for reducing the thickness deviation of the damaged layer on the wafer as set forth in claim 6, wherein the temperature of the chemical solution is always 80-85 ℃ during the whole process.

8. The etching process as claimed in claim 7, wherein the circulation flow rate of the potassium hydroxide is 22-35L/min.

9. The etching process for reducing the thickness deviation value of the damaged layer of the wafer as set forth in any one of claims 1 to 2, 4 and 7 to 8, wherein the step of bubbling nitrogen gas into the chemical solution is further included from the time the wafer enters the chemical solution to the time the wafer leaves the chemical solution.

10. The etching process for reducing the thickness deviation of the damaged layer of the wafer as claimed in claim 9, wherein the nitrogen gas is provided along a width direction of the vertical wafer, the nitrogen gas bubbles obliquely upwards along an outer edge of the wafer, and an included angle between a direction of the nitrogen gas jet and a vertical diameter of the wafer is 35-45 °.

Technical Field

The invention belongs to the technical field of semiconductor silicon wafer processing, and particularly relates to a corrosion process for reducing thickness deviation value of a damaged layer of a wafer.

Background

After the semiconductor silicon wafer is thinned and ground, a mechanical damage layer, mainly silicon, is formed on the surface of the silicon wafer and needs to be removed before polishing, the mechanical damage layer is removed by adopting alkali liquor corrosion in the prior art, and the thickness uniformity of the corrosion damage layer directly influences TTV (time to live) in geometric parameters and physicochemical test results, and even influences the production of the subsequent process. In the existing corrosion process, the wafer is taken out according to the original placement state after entering the corrosion tank, but the operation is easy to cause the part which enters firstly to be taken out, but not to be arranged first in first out, so that the time for the part which enters firstly to be immersed in the liquid medicine is long, the corrosion thickness is large, the thickness of the damaged layer of the part which enters firstly and the part which enters later is unevenly removed, the thickness deviation of the two ends after corrosion is large, and reaches 400 plus 500nm, and the product quality of the wafer is seriously influenced.

Disclosure of Invention

The invention provides a corrosion process for reducing the thickness deviation value of a damaged layer of a wafer, and solves the technical problems of uneven corrosion thickness and larger deviation value in the prior art.

In order to solve the technical problems, the invention adopts the technical scheme that:

a corrosion process for reducing thickness deviation value of a damaged layer of a wafer comprises the following steps:

synchronously feeding a plurality of wafers into the liquid medicine and stably placing the wafers, wherein the V-shaped grooves of all the wafers are arranged towards the same direction;

controlling the wafer to synchronously rotate (N +0.5) circles in the liquid medicine at a set rotating speed, wherein N is an integer greater than 1;

extracting the wafer and leaving the liquid medicine;

wherein the time from the wafer entering the liquid medicine to the stable standing is the same as the time from the wafer standing to the wafer being completely extracted and leaving the liquid medicine.

Further, when the wafer enters the liquid medicine, the V-shaped grooves of the wafer are all vertically arranged upwards; and after the wafer rotates and stands, the V-shaped grooves are vertically arranged downwards until the wafer is taken out.

Further, the time of the wafer from the time when the wafer enters the liquid medicine to the time when the wafer is stably placed is 8-10 s.

Further, the wafer is rotated in a clockwise direction, and the rotation speed thereof is constant.

Further, the time for rotating the wafer is 80-100 s.

Further, the liquid medicine is pure potassium hydroxide solution, and the mass concentration of the liquid medicine is 42-48%; preferably, its mass concentration is 45%.

Furthermore, the temperature of the liquid medicine is always 80-85 ℃ in the whole process.

Further, the circulation flow of the potassium hydroxide is 22-35L/min.

Further, the method further includes a step of bubbling nitrogen gas into the chemical liquid from the time when the wafer enters the chemical liquid to the time when the wafer leaves the chemical liquid.

Furthermore, the nitrogen is arranged along the width direction of the vertically arranged wafer, the nitrogen bubbles upwards along the outer edge of the wafer in an inclined manner, and the included angle between the nitrogen spraying direction and the vertical diameter of the wafer is 35-45 degrees.

The corrosion process for reducing the thickness deviation value of the damaged layer of the wafer is designed, so that the part of the wafer which enters the liquid medicine first is ensured to leave the liquid medicine first, namely the part of the wafer which enters the liquid medicine first is ensured to enter the liquid medicine first and then enter the liquid medicine first; and simultaneously, the time for the wafer to completely enter the liquid medicine is required to be the same as the time for the wafer to completely leave the liquid medicine and be extracted, and the standing buffer time of the wafer in the liquid medicine after the wafer rotates is shortened as much as possible, so that the corrosion time of all wafers in the liquid medicine is ensured to be the same to the maximum extent, the thickness deviation value of the damaged layer of the wafer surface is reduced, the deviation value is reduced from 400-200 nm to 150-200nm, and the surface flatness of the wafer is improved.

Drawings

FIG. 1 is a schematic view of an apparatus for an etching process according to an embodiment of the present invention;

FIG. 2 is a flow chart of an etching process according to an embodiment of the present invention.

In the figure:

10. tank 20, adjusting rod 30, wafer

40. Nitrogen gas pipe

Detailed Description

The invention is described in detail below with reference to the figures and specific embodiments.

Specifically, the etching process for reducing the thickness deviation value of the damaged layer of the wafer provided in this embodiment is performed in the apparatus shown in fig. 1, and includes a tank 10 and three adjusting rods 20, where the tank 10 is of a rectangular structure, the adjusting rods 20 are provided with a plurality of annular clamping grooves for placing the wafer 30, one end of each adjusting rod 20 is movably fixed at one end of the tank 10, and the other end of each adjusting rod is driven and controlled by an external engine. The wafer is vertically placed on the clamping groove, and the adjusting rod 20 synchronously rotates to drive the wafer 30 to synchronously rotate along with the rotation, so that the corrosion of the wafer 30 in the groove body 10 is facilitated; but also can make the V-shaped grooves on the wafer 30 all set towards the same direction, thereby controlling the rotation number of the wafer 30.

The tank body 10 is also internally provided with a nitrogen pipe 40 for bubbling, the nitrogen pipe 40 is symmetrically arranged outside the graph range of the semicircular structure surrounded by the adjusting rod 20 along the length direction of the tank body 10 and is positioned below the wafer 30, so that the influence of liquid flow sprayed from the nitrogen pipe 40 on the placement stability of the wafer 30 in the rotating process is avoided. The nitrogen gas flow provided along the longitudinal direction of the nitrogen gas pipe 40 covers the width direction in which the wafer 30 is placed, and the nitrogen gas discharged from the exhaust hole is ejected obliquely upward toward the side away from the wafer 30. The nitrogen gas exiting the vent opening forms an angle alpha of 35-45 deg. with the longitudinal axis of the wafer 30.

An etching process for reducing thickness deviation of a damaged layer of a wafer, as shown in fig. 2, includes the steps of:

s1: the wafer 30 is put into the liquid medicine and is stably placed

Synchronously feeding a plurality of vertically arranged wafers into a tank body 10 loaded with liquid medicine through a manipulator, arranging an adjusting mechanism which is used for bearing the wafers and controlling the wafers to rotate and move in the tank body 10, and slowly feeding the wafers into the liquid medicine at a certain speed until the wafers are stably placed; in this process, all the V-grooves of the wafer 30 are oriented in the same direction, and in this embodiment, are oriented vertically upward.

In this process, all the V-shaped grooves of the wafer 30 are arranged in the same direction and vertically upward, which is beneficial to observing the position of the wafer 30.

Preferably, the time from the time the wafer 30 enters the drug solution until it is stably placed in the card slot 23 is 8-10 seconds.

Further, the liquid medicine is pure potassium hydroxide solution, and the mass concentration of the liquid medicine is 42-48%; preferably, its mass concentration is 45%. And the temperature of the liquid medicine is always kept between 80 and 85 ℃. Meanwhile, in order to ensure the setting of the concentration, the circulating flow of the potassium hydroxide liquid medicine is required to be 22-35L/min.

S2: controlling the wafer 30 to rotate synchronously for (N +0.5) turns

The adjusting rods 20 are controlled to rotate, so as to drive the wafer 30 to rotate in the liquid medicine, all the adjusting rods 20 rotate in the same direction, in this embodiment, the adjusting rods 20 all rotate clockwise, the rotation speed is constant and is 12-25 °/s, and the time for the adjusting rods 20 to drive the wafer 30 to rotate in the liquid medicine is 80-100 s. In the process, the time for grabbing the wafer 30 by the external manipulator is also included, namely the adjusting rod 20 stops after the rotation is finished; and after the wafer 30 is grabbed by the manipulator in the liquid to be kept still and buffered for a period of time, the wafer 30 is extracted and leaves the tank 10.

The adjusting rod 20 drives the wafer 30 to synchronously rotate (N +0.5) circles at a rotating speed of 12-25 degrees/s, wherein N is an integer larger than 1, namely the wafer 30 is driven to rotate for a plurality of whole circles and then rotate 180 degrees, so that the opening of the V-shaped groove is vertically arranged downwards, after the wafer 30 is rotated and stood, the V-shaped groove is vertically arranged downwards until the wafer is taken out, and further the part of the wafer 30, which firstly enters the liquid medicine level, is upwards arranged, when the wafer is taken out, the part of the wafer 30, which firstly enters the liquid medicine level, is firstly left because the placing time and the taking time are controlled to be the same, so that the part of the wafer 30, which firstly enters the liquid medicine level, is firstly left, the first-in first-out operation is ensured, under the condition that other corrosion conditions are not changed, the consistency of the corrosion time of the wafer 30 in the liquid medicine is ensured, and the change, the uniformity and consistency of the corrosion thickness of the wafer 30 are improved, so that a foundation is laid for obtaining qualified geometric parameters in subsequent polishing processing, and the production efficiency is improved.

In order to further ensure the uniformity of the liquid medicine dispersion, the method further comprises the step of introducing nitrogen into the liquid medicine and bubbling the nitrogen throughout the process from the time when the wafer 30 enters the liquid medicine to the time when the wafer leaves the liquid medicine, namely the whole etching process. Namely, nitrogen is arranged along the vertical width direction of the wafer 30, namely, nitrogen pipes 40 which discharge nitrogen into the liquid medicine are arranged on the two vertically arranged sides of the wafer 30, the nitrogen discharged from the nitrogen pipes 40 bubbles upwards along the outer edge of the wafer 30, and the included angle alpha between the spraying direction of the nitrogen and the vertical diameter of the wafer 30 is 35-45 degrees. The gas flow ejected from the nitrogen gas pipe 40 during the rotation is prevented from affecting the stability of the wafer 30 in placement. Meanwhile, the angle is not far away from the wafer 30, and the rotation stability of the wafer 30 is not influenced; moreover, the angle can further ensure the uniformity of the distribution of the liquid medicine, so that the double-sided corrosion of the wafer 30 is more uniform and consistent.

S3: extracting the wafer 30 from the solution

And controlling the wafer 30 to be stably extracted from the liquid medicine entering and completely leave the liquid level of the liquid medicine, wherein the time from the liquid medicine entering to the stable standing of the wafer 30 is the same as the time from the standing completion to the complete extraction and the liquid medicine leaving of the wafer 30. The time is 8-10 s.

The first embodiment is as follows:

corroding the wafer with the diameter of 300mm of the wafer 30 as follows:

s1: the wafer 30 is put into the liquid medicine and is stably placed

Vertically clamping a plurality of wafers 30 by a movable manipulator and vertically putting the wafers into the liquid medicine, wherein all the V-shaped grooves of the wafers 30 are vertically arranged upwards; the time taken from the entry of the drug solution to the leaving thereof was 8 seconds.

Wherein the liquid medicine is a pure potassium hydroxide solution with the mass concentration of 45%, the constant temperature of the liquid medicine is 82 ℃, and the circulating flow of the liquid medicine is 30L/min; and simultaneously introducing nitrogen gas obliquely upwards along the outer edge of the wafer 30 into the liquid medicine for bubbling, wherein the included angle alpha between the nitrogen gas injection direction and the vertical diameter of the wafer 30 is 45 degrees.

S2: controlling the wafer 30 to rotate synchronously

After the wafer 30 is stably placed, the adjusting rod 20 is controlled to rotate the wafer 30 clockwise for 7 circles, and then rotate for half a circle, that is, after 7.5 circles of rotation, all the V-shaped grooves of the wafer 70 are vertically arranged downward, and in the process, the time for the wafer 70 to be rotated is 85 s. And simultaneously, the wafer is kept still for 5s and is completely clamped and fixed by the manipulator within the standing and buffering time, and the V-shaped grooves of all the wafers are vertically arranged downwards so as to be extracted next step.

S3: extracting the wafer 30 from the solution

The robot is controlled to pick up all the wafers 30 and leave the solution completely, the time shared in this process is 8s, and the time for picking up and placing the wafers is the same.

1. The thinning and thinning process designed by the invention can accurately control the rotation angle of the wafer and enable the V-shaped grooves in all the wafers to synchronously move in the same direction, so that the positions of the V-shaped grooves in the wafers entering the tank body are different from the positions of the V-shaped grooves leaving the tank body, the V-shaped grooves rotate 180 degrees relative to the initial entering direction, all parts on the two sides of the wafers are corroded in the tank body in the same time, the parts which enter the liquid medicine in the tank body firstly leave the liquid medicine, the difference of the double-sided corrosion thickness of the wafers is reduced to the maximum extent, the uniformity and the consistency of the corrosion thickness of the wafers are improved, the foundation is laid for obtaining qualified geometric parameters for subsequent polishing processing, and the production efficiency is improved.

2. The thinning process provided by the invention ensures that the part of the wafer which enters the liquid medicine first leaves the liquid medicine first, namely, the part of the wafer which enters the liquid medicine first is ensured to be first in and first out; and simultaneously, the time for the wafer to completely enter the liquid medicine is required to be the same as the time for the wafer to completely leave the liquid medicine and be extracted, and the standing buffer time of the wafer in the liquid medicine after the wafer rotates is shortened as much as possible, so that the corrosion time of all wafers in the liquid medicine is ensured to be the same to the maximum extent, the thickness deviation value of the damaged layer of the wafer surface is reduced, the deviation value is reduced from 400-200 nm to 150-200nm, and the surface flatness of the wafer is improved.

The embodiments of the present invention have been described in detail, and the description is only for the preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. All equivalent changes and modifications made within the scope of the present invention shall fall within the scope of the present invention.