A manipulator and a wafer etching method for improving the uniformity of slot etching by using the same

Abstract

The present invention discloses a manipulator and a wafer etching method for improving the uniformity of slot etching by using the same. The etching method includes n etching processes, and each etching process includes the following steps: Step 1, the manipulator feeds the wafer into the etching solution: the manipulator holds the wafer above the etching solution tank body, one robotic arm remains stationary, and the other robotic arm rotates outward and unfolds. The wafer rolls obliquely downward along the lower arm of the stationary robotic arm and falls into the etching solution below; Step 2, the manipulator vertically picks up the wafer from the bottom of the tank. Using this manipulator makes the wafer etching method have the characteristic of improving the uniformity of slot metal etching of the wafer.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor manufacturing, and particularly to a manipulator and a wafer etching method for improving the uniformity of slot etching by using the same. Background Art

[0002] In the manufacturing and processing of semiconductor devices, many devices need to be wet-etched with Au and Cr to form a specific metal pattern layer; the slot cleaning machine is widely used due to its high consistency and large production capacity. Conventionally, a mixed solution of KI and I2 is used as the Au etchant because the mixed solution of KI and I2 has advantages such as non-toxicity, recyclability, and good stability, and a Cr7 solution is used as the Cr etchant, and the Cr7 solution is a mixed solution of ammonium cerium nitrate and nitric acid.

[0003] The existing process of repeatedly immersing the wafer in the etchant is as follows: in each wafer etching process, the manipulator is used to clamp the wafer above the etchant tank, the manipulator is released, so that the wafer vertically falls into the lower etchant tank. After the wafer is etched, the manipulator is used to vertically clamp the wafer again, and then the above steps are repeated. After repeating many times, the wafer etching is completed; using this process, since the wafer enters and exits the etchant tank vertically up and down each time, the order of each part of the wafer in the vertical direction entering and exiting the etchant tank is different. The part of the wafer that enters the etchant first exits the etchant later, and the part that enters the etchant later exits the etchant first. The part closer to the bottom of the wafer is etched for a longer time, and the part closer to the top of the wafer is etched for a shorter time. The etching time of each part of the wafer in the vertical direction is different; therefore, single etching will cause uneven etching of the wafer. Repeating the wafer etching process multiple times (2 to 4 times), in the next wafer etching process, the order of the wafer entering and exiting remains unchanged. The part that entered first and exited later in the previous etching process of the wafer is still the part that enters first and exits later in the next etching process, and the part that entered later and exited first in the previous etching process of the wafer is still the part that enters later and exits first in the next etching process; therefore, after multiple etching processes, the etching time difference of each part of the wafer is large, and the etching uniformity difference from the top to the bottom of the wafer cannot be solved. Using the above existing etching process, the uniformity of the wafer will be poor, and the etching will cause metal layer residues in the wafer, which is manifested as poor uniformity in the CD of the metal pattern after etching on the product.

[0004] In view of the above problems, the present invention designs a manipulator and a wafer etching method for improving the uniformity of slot etching by using the same, and this case is thus produced. Summary of the Invention

[0005] The present invention provides a manipulator and a wafer etching method for improving the uniformity of slot etching by using the same, so that the wafer etching method has the characteristic of improving the uniformity of wafer slot metal etching; specifically, the present invention is realized through the following technical solutions:

[0006] A wafer etching method for improving the uniformity of slot etching, including n etching processes, n≥2, and each etching process includes the following steps:

[0007] Step 1: The manipulator sends the wafer into the etching solution: The manipulator holds the wafer above the etching solution tank. One robotic arm remains stationary, and the other robotic arm rotates and unfolds outward. The wafer rolls obliquely downward along the lower arm of the stationary robotic arm and falls into the etching solution below.

[0008] Step 2: The manipulator picks up the wafer from the tank.

[0009] Further, after Step 1 is completed, the rotation angle of the wafer is a, and n*a = 360°.

[0010] Each time the wafer is transferred into the etching solution for etching, the manipulator holds the wafer above the tank, keeps one robotic arm stationary, and releases the single robotic arm. At this time, the wafer will roll obliquely downward along the lower arm of the stationary robotic arm, completing the action of rotating while falling. By rotating the wafer by a certain angle, the parts near the bottom and near the top in the first etching process will no longer be near the bottom and near the top in the second etching process. The parts that enter first and exit later in the previous etching process of the wafer will become the parts that enter later and exit first in the next etching process, and the parts that enter later and exit first in the previous etching process of the wafer will become the parts that enter first and exit later in the next etching process. When multiple etching processes are completed, after the wafer rotates 360 degrees in the same direction, each part of the wafer has rotated 360 degrees. During the entire etching process, the etching time of each part of the wafer is almost the same, and the overall etching of the wafer is relatively uniform.

[0011] Further, the manipulator used in the above wafer etching method includes two robotic arms. When the manipulator sends the wafer into the etching solution, the stationary side of the manipulator is the first robotic arm, and the other side of the manipulator is the second robotic arm. The first robotic arm and the second robotic arm are hinged, and the cooperation of the two robotic arms is used to hold the wafer. Each robotic arm includes an upper arm and a lower arm connected to the lower end of the upper arm. The length of the lower arm of the first robotic arm is greater than the length of the lower arm of the second robotic arm.

[0012] By increasing the length of the lower arm of the first robotic arm, it is ensured that the wafer rotates and rolls during the falling process.

[0013] Further, a converging shape is formed between the lower arm of the first robotic arm and the lower arm of the second robotic arm.

[0014] This shape can ensure that the wafer is held.

[0015] Further, each robotic arm is composed of an upper arm and a lower arm connected to the lower end of the upper arm. The angle formed after the connection of the upper arm and the lower arm is the angle between the upper and lower arms. The range of the angle between the upper and lower arms of the first robotic arm is between 110 degrees and 160 degrees, and the range of the angle between the upper and lower arms of the second robotic arm is between 110 degrees and 160 degrees.

[0016] Within this angle range, the wafer is convenient to hold.

[0017] Further, the angles between the upper and lower arms of the two robotic arms are the same.

[0018] When the two robotic arms hold the wafer, the forces on the two robotic arms are the same, so that the service lives of the two robotic arms are approximately the same.

[0019] Further, the range of the closing angle of the robotic hand is between 20 degrees and 70 degrees, and the range of the opening angle of the robotic hand is between 30 degrees and 120 degrees.

[0020] Further, when the first robotic arm is on the left side of the second robotic arm, the wafer rotates clockwise; when the first robotic arm is on the right side of the second robotic arm, the wafer rotates counterclockwise.

[0021] Further, when the robotic hand holds the wafer above the etching solution tank body, the range of the angle between the lower arm of the first robotic arm and the horizontal plane is between 45 degrees and 60 degrees. When the angle between the lower arm of the first robotic arm and the horizontal plane is within this range, it is convenient for the wafer to roll down. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of a robotic hand holding a wafer above a tank body provided by the present invention;

[0023] Figure 2 It is a schematic diagram of the first robotic arm of a robotic hand not moving and the second robotic arm loosening provided by the present invention;

[0024] Figure 3 It is a schematic diagram of a wafer rolling along the first robotic arm provided by the present invention;

[0025] Figure 4 It is a schematic diagram of a wafer falling to the bottom of the tank body provided by the present invention.

[0026] Wherein: 1. Robotic arm; 2. First robotic arm; 3. Second robotic arm; 4. Upper arm; 5. Lower arm; 6. Wafer; 7. Tank body; 8. Lower arm of the first robotic arm; 9. Lower arm of the second robotic arm. DETAILED DESCRIPTION OF THE INVENTION

[0027] The present invention will be further described below in conjunction with the drawings and specific embodiments.

[0028] A wafer etching method for improving the uniformity of slot etching. This method includes n etching processes, where n is two or more than two. Each etching process is described as follows:

[0029] The manipulator holds the wafer 6 above the tank 7. As shown in Figure 1 the figure, the first robotic arm 2 remains stationary, and the second robotic arm 3 rotates outward and unfolds, so that the angle formed between the first robotic arm 2 and the second robotic arm 3 gradually increases, as shown in Figure 2 the figure; since the lower arm 8 of the first robotic arm forms an acute angle with the horizontal plane and the first robotic arm 2 remains stationary, as the second robotic arm 3 rotates outward and unfolds, the wafer 6 will roll obliquely downward along the lower arm 8 of the first robotic arm. The wafer 6 completes the action of falling while rotating, and part of the gravitational potential energy of the wafer 6 is converted into the rotational kinetic energy of the wafer 6, as shown in Figure 3 the figure; when the wafer 6 breaks away from the lower arm 8 of the first robotic arm, due to inertia, the wafer 6 will continue to rotate. Then when the wafer 6 falls to the limiting structure at the bottom of the tank 7, the limiting structure is arc-shaped, the rotation angle of the wafer 6 is a, and the horizontal movement distance of the wafer 6 is X, as shown in Figure 4 the figure.

[0030] The manipulator then vertically clamps the wafer 6 out of the tank 7 to complete one etching process.

[0031] Repeat the etching process multiple times so that when all the etching processes are completed, the wafer 6 just rotates 360°, that is, a*n = 360°, realizing the compensation of the total etching amount at the top / bottom of the slot in the wet metal etching of the slot. The time of each part of the wafer 6 being etched is roughly the same, thus improving the uniformity within the wafer 6.

[0032] According to the process treatment requirements, such as the total etching amount and the requirement of uniformity, and at the same time according to the number of times the wafer 6 is immersed in the etching solution, determine the number n of rotations of the wafer 6, so as to determine the value of the rotation angle a of each immersion and rotation of the wafer 6.

[0033] When performing Au etching, the etching sequence of the wafer 6 is as follows: KI, I2 → DIW → KI, I2 → DIW → KI, I2 → DIW → KI, I2 → DIW; therefore, the wafer 6 is immersed in the KI, I2 solution four times, and the rotation angle of each wafer 6 is controlled to 90 degrees. When the four etching processes are completed, the wafer 6 just rotates 360 degrees.

[0034] When performing Cr etching, the etching sequence of the wafer 6 is as follows: CR7 → DIW → CR7 → DIW → CR7 → DIW → CR7 → DIW; therefore, the wafer 6 is immersed in the CR7 solution four times, and the rotation angle of each wafer 6 is controlled to 90 degrees. When the four etching processes are completed, the wafer 6 just rotates 360 degrees.

[0035] The structure of the robot arm used in the above method for improving the uniformity of wafer trench etching is described as follows:

[0036] As Figure 1 shown, the robot arm is used to hold and transport the wafer 6 into the tank 7 filled with etching solution, and pick up the etched wafer 6. The robot arm includes two vertically arranged robotic arms 1, which are the first robotic arm 2 and the second robotic arm 3 respectively. The wafer 6 is clamped through the cooperation of the two robotic arms 1; the first robotic arm 2 and the second robotic arm 3 are hinged; for the convenience of subsequent description, when the robot arm holds the wafer 6 and the first robotic arm 2 and the second robotic arm 3 no longer move relative to each other, the angle formed between the first robotic arm 2 and the second robotic arm 3 at this time is named the robot arm closing angle; when the robot arm releases the wafer 6 and the first robotic arm 2 and the second robotic arm 3 no longer move relative to each other, the angle formed between the first robotic arm 2 and the second robotic arm 3 at this time is named the robot arm opening angle.

[0037] The range of the robot arm closing angle is between 20 degrees and 70 degrees, and the range of the robot arm opening angle is between 30 degrees and 120 degrees.

[0038] As Figure 4 shown, each robotic arm 1 is composed of an upper arm 4 and a lower arm 5 connected to the lower end of the upper arm 4. The angle formed after the connection of the upper arm 4 and the lower arm 5 is the upper and lower arm angle B; after the two robotic arms 1 are installed, the lower arms 8 of the first robotic arm and the lower arms 9 of the second robotic arm form a converging shape, so as to facilitate clamping the wafer 6.

[0039] The range of the upper and lower arm angle B is between 110 degrees and 160 degrees.

[0040] When the robot arm holds the wafer 6 above the etching solution tank, the range of the angle D between the lower arm 8 of the first robotic arm and the horizontal plane is between 45 degrees and 60 degrees. Within this range, it is convenient for the wafer 6 to roll down.

[0041] As Figure 4 shown, the length of the lower arm 8 of the first robotic arm is greater than the length of the lower arm 9 of the second robotic arm, so as to increase the rolling path of the wafer 6 on the lower arm 8 of the first robotic arm, give the wafer 6 greater rotational kinetic energy, and facilitate the rotation of the wafer 6. The length of the lower arm 8 of the first robotic arm should be greater than or equal to 2X to ensure the process when the wafer slides.

[0042] When the first robotic arm 2 is on the left side of the second robotic arm 3, the wafer 6 rotates clockwise; when the first robotic arm 2 is on the right side of the second robotic arm 3, the wafer 6 rotates counterclockwise.

[0043] Physical factors such as the falling height of the wafer 6, the magnitude of the angle B between the upper and lower arms, the depth of the etching solution, the density of the etching solution, the angle D between the lower arm 8 of the first robotic arm and the horizontal plane, and the length of the part of the lower arm 8 of the first robotic arm where the wafer 6 rolls will all affect the magnitude of the rotation angle a of the wafer 6 during each etching process. Therefore, the magnitude of the rotation angle a of the wafer 6 during each dipping process can be controlled by adjusting the above-mentioned relevant physical factors.

[0044] The above is the preferred embodiment of the present invention. Under the premise of the inventive concept of the present invention, several other simple substitutions and modifications should be regarded as belonging to the protection scope of the present invention.

Claims

1. A wafer etching method for improving the uniformity of trench etching, characterized in that: It includes n etching processes, where n ≥ 2, and each etching process includes the following steps: Step 1: The manipulator feeds the wafer into the etching solution in the tank: The manipulator includes two vertically arranged robotic arms, which are divided into the first robotic arm and the second robotic arm. The first robotic arm and the second robotic arm are hinged, and the wafer is clamped through the cooperation of the two robotic arms, so that the circular edge of the wafer is clamped by the two robotic arms and the wafer is perpendicular to the bottom surface of the tank; each robotic arm includes an upper arm and a lower arm connected to the lower end of the upper arm. The lower arms of the first robotic arm and the second robotic arm form a converging shape. The length of the lower arm of the first robotic arm is greater than the length of the lower arm of the second robotic arm. The lower arm of the first robotic arm forms an acute angle with the horizontal plane; A limiting structure is arranged at the bottom of the tank. The manipulator clamps the wafer above the etching solution tank. The first robotic arm remains stationary, and the second robotic arm rotates outward and unfolds. The wafer rolls obliquely downward along the lower arm of the first robotic arm and falls onto the limiting structure in the lower etching solution; Let the horizontal distance between the center of the wafer before the second robotic arm rotates outward and unfolds and the center of the wafer that has fallen onto the limiting structure be X. Let the rotation angle of the wafer be a after the wafer is clamped by the two robotic arms and falls onto the limiting structure, and n*a = 360°. The length of the lower arm of the first robotic arm ≥ 2X; Step 2: The manipulator picks up the wafer from the tank.

2. The wafer etching method according to claim 1, characterized in that: The angle formed after the upper arm and the lower arm are connected is the upper and lower arm angle; the range of the upper and lower arm angle of the first robotic arm is between 110 degrees and 160 degrees, and the range of the upper and lower arm angle of the second robotic arm is between 110 degrees and 160 degrees.

3. The wafer etching method according to claim 2, wherein: The upper and lower arm angles of the two robotic arms are the same.

4. The wafer etching method according to claim 1, wherein: Let the angle formed between the first robotic arm and the second robotic arm when the manipulator clamps the wafer and the two robotic arms no longer move relative to each other be the manipulator closing angle; let the angle formed between the first robotic arm and the second robotic arm when the manipulator releases the wafer and the two robotic arms no longer move relative to each other be the manipulator opening angle. The range of the manipulator closing angle is between 20 degrees and 70 degrees, and the range of the manipulator opening angle is between 30 degrees and 120 degrees.

5. The wafer etching method according to claim 1, characterized in that: When the first robotic arm is on the left side of the second robotic arm, the wafer rotates clockwise; when the first robotic arm is on the right side of the second robotic arm, the wafer rotates counterclockwise.

6. The wafer etching method according to claim 1, wherein: When the manipulator clamps the wafer above the etching solution tank, the range of the angle between the lower arm of the first robotic arm and the horizontal plane is between 45 degrees and 60 degrees.

Images