Method for improving charge effect defect of compound substrate photoetching process

Abstract

The invention discloses a method for improving a charge effect defect of a compound substrate photoetching process, and belongs to the technical field of integrated circuits. The method comprises the following steps: (1) spraying a developing solution: placing a wafer on a developing unit bearing table, swinging from one side edge of the wafer to the other side edge by using an H-shaped nozzle, and spraying the developing solution; wherein the rotating speed of the wafer is continuously changed between 100 rpm and 1000 rpm; (2) spraying deionized water: swinging from the edge of one side of the wafer to the edge of the other side of the wafer by using a columnar nozzle, and spraying the deionized water to carry out development reactant replacement; wherein the rotating speed of the wafer is set as follows: high speed, low speed and high speed, and the deionized water can more sufficiently replace the developing reactants through variable-speed rotation of the wafer, so that a more sufficient cleaning effect is achieved; and (3) spin-drying: spin-drying the wafer in a manner of rotating at a high speed and then rotating at a low speed. According to the method, the charge generation amount can be reduced to the greatest extent, so that the charge effect of the compound substrate wafer is thoroughly solved.

Description

Technical Field

[0001] The invention relates to the technical field of integrated circuits, and in particular to a method for improving charging effect defects in a compound substrate photolithography process. Background Art

[0002] In semiconductor technology, as semiconductors develop towards high frequency, high power and high integration, higher and higher requirements are put forward for the purity of semiconductor materials and various reagents used in the process of making semiconductor devices and integrated circuits. Compound semiconductors usually refer to crystalline inorganic compound semiconductors, mainly binary compounds such as gallium arsenide, indium phosphide, cadmium sulfide, bismuth telluride, cuprous oxide, etc., followed by binary and multi-element compounds such as gallium aluminum arsenide, indium gallium arsenic phosphide, gallium arsenide phosphide, copper indium selenide and some rare earth compounds (such as SeN, YN, La2S3, etc.). Compound semiconductors can be used to prepare optoelectronic devices, ultra-high-speed microelectronic devices and microwave devices.

[0003] In the existing conventional compound process, during the development process, due to the influence of the compound wafer material (wafers based on silicon carbide, gallium nitride, etc.) and size, the pre wet (drying) and rinse (liquid spraying) in the process require a higher rotation speed, resulting in uneven accumulation of charges on the surface of the wafer (SIC wafer AM layer sample) in the cavity, and severe charging effects on the wafer in the machine. As the subsequent electron beam continues to scan the sample surface, the generation, transportation and emission of secondary electrons are dynamically affected, resulting in jitter, drift and local blackening, which seriously affects the image quality and product yield, and makes the CD machine unable to accurately measure. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide a method for improving the charging effect defects of compound substrate lithography process. Based on the original traditional process, the method changes the dynamic puddle mode to multiple variable speed spraying of developer, and at the same time, the rinse and spin speeds are split from a single speed to a variable speed, thereby minimizing the amount of charge generated, thereby completely solving the charging effect of compound substrate wafers.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] A method for improving charging effect defects in a compound substrate photolithography process, the method is to perform a development process on a compound semiconductor wafer after being coated, exposed, and etched in the photolithography process to improve its charging effect defects; the method specifically comprises the following steps:

[0007] (1) Spraying developer: Place the wafer on the wafer stage of the developing unit, and use an H-shaped nozzle to swing from one edge of the wafer to the other edge and spray the developer; wherein: the wafer speed is continuously changed between 100-1000 rpm;

[0008] (2) Deionized water spraying: Use a columnar nozzle to swing from one edge of the wafer to the other edge and spray deionized water to replace the developing reactants; wherein: the wafer rotation speed is set to: first high speed, then low speed, and then high speed. Through the variable speed rotation of the wafer, the deionized water can more fully replace the developing reactants, achieving a more complete cleaning effect;

[0009] (3) Spin drying: The wafer is spun dry by first rotating at high speed and then at low speed;

[0010] In the above step (1), the wafer is cyclically rotated in the order of low speed rotation-high speed rotation. The wafer rotation speed is 100-500rpm during low speed rotation, and the wafer rotation speed is greater than 500rpm and less than or equal to 1000rpm during high speed rotation. The higher the rotation speed, the more charges are generated, so it is necessary to find the optimal balance parameters within the adjustment range according to the actual application situation.

[0011] In the above step (1), the developer flow rate is 400-1000 ml / min, and the total spraying time is 20-80 s.

[0012] In the above step (2), the high-speed water washing speed of the wafer is 800-1500rpm, and the single high-speed water washing time is 10-60s; the low-speed water washing speed of the wafer is 100-500rpm, and the low-speed water washing time is 10-60s.

[0013] In the above step (2), the flow rate of deionized water is 500-1500 ml / min.

[0014] In the above step (3), the low-speed rotation speed of the wafer is 300-1000 r / min, the high-speed rotation speed is greater than 1000 r / min and less than or equal to 2000 r / min, and the low-speed and high-speed rotation times of the wafer are both 10-30 s.

[0015] The material of the wafer targeted by the method of the present invention is compound semiconductor.

[0016] The design principle and beneficial effects of the present invention are as follows:

[0017] 1. The improved developing method of the present invention can avoid the charging effect of the compound wafer, thereby avoiding adverse effects on the conductive properties of the product;

[0018] 2. The present invention can optimize process performance by adjusting the development process formula parameters only, without adding other process steps or hardware output, and has been widely implemented in mass production in wafer foundries;

[0019] 3. In the display process of the present invention, the development time is changed from the traditional puddle mode to the high-speed liquid spray mode, which greatly reduces the development time and greatly improves the machine production capacity; BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 CD SEM data after traditional wafer development.

[0021] Figure 2 CD SEM data of the wafer after development under the conditions of Example 1.

[0022] Figure 3 The long-term CD value stability curves of Example 1 and the original developing conditions are shown in FIG. DETAILED DESCRIPTION

[0023] In order to further understand the present invention, the present invention is described below in conjunction with examples, but the examples are only for further elaboration of the features and advantages of the present invention, rather than for limiting the claims of the present invention.

[0024] Embodiment 1:

[0025] This embodiment provides a method for improving the charging effect of compound semiconductors without affecting the line width of products. The method is to perform a development process on a gallium nitride wafer after photoresist coating, exposure and etching in a photolithography process. The specific process is as follows:

[0026] The first step: use the developing unit to spray the display liquid, specifically: place the wafer on the wafer stage of the developing unit, use an H-type nozzle to swing from one edge of the wafer to the other edge and spray the developer, the wafer rotates in the order of low speed first and then high speed, the low speed of the wafer is 300rpm, the spraying time is about 30s at low speed, the high speed of the wafer is 550rpm, the spraying time is about 30s at high speed, and the developer flow rate is 600ml / min.

[0027] Step 2: Use a cylindrical nozzle to swing and spray deionized water from one edge of the wafer to the other edge. The wafer rotation speed is 850rpm, the deionized water flow rate is 800mL / min, and the spraying time is 20s.

[0028] Step 3: Use a cylindrical nozzle to swing and spray deionized water from one edge of the wafer to the other edge. The wafer rotation speed is 300rpm, the deionized water flow rate is 800mL / min, and the spraying time is 30s.

[0029] Step 4: Use a cylindrical nozzle to swing and spray deionized water from one edge of the wafer to the other edge. The wafer rotation speed is 1000rpm, the deionized water flow rate is 800mL / min, and the spraying time is 20s.

[0030] Step 5: The wafer is spun dry by rotating it at high speed first and then at low speed. The low speed of the wafer is 600r / min, the high speed of the wafer is 1500rpm, and the time of low speed and high speed rotation is 25s.

[0031] After development, CD-SEM was used to observe and measure the height of RDL copper at the deep hole structure at the center and edge of the wafer. Figure 1 CD SEM data after traditional wafer development. Figure 2 CD SEM data of the wafer after development under the conditions of Example 1. Figure 3 The long-term CD value stability curve of Example 1 and the original development conditions. Through the comparison of the above data, it can be seen that the morphology is clear after development using the method of the present invention, the conductivity is good, the 0.1umCD uniformity is improved from 5% to 0.3%, and it is long-term stable. It proves that the process of the present invention effectively avoids the charging effect during the compound development process, thereby avoiding adverse effects on the conductivity of the product; greatly improving the product yield.

Claims

1. A method for improving charging effect defects in a compound substrate lithography process, characterized in that: The method is to perform a development process on a compound semiconductor wafer after being coated, exposed and etched in a photolithography process to improve its charging effect defects; the method specifically comprises the following steps: (1) Spraying developer: Place the wafer on the wafer stage of the developing unit, and use an H-shaped nozzle to swing from one edge of the wafer to the other edge and spray the developer; wherein: the wafer speed is continuously changed between 100-1000 rpm; (2) Deionized water spraying: Use a columnar nozzle to swing from one edge of the wafer to the other edge and spray deionized water to replace the developing reactants; wherein: the wafer rotation speed is set to: first high speed, then low speed, and then high speed. Through the variable speed rotation of the wafer, the deionized water can more fully replace the developing reactants, achieving a more complete cleaning effect; (3) Spin drying: The wafer is spun dry by first rotating at high speed and then at low speed.

2. The method for improving charging effect defects in a compound substrate lithography process according to claim 1, characterized in that: In step (1), the wafer is cycled in the order of low-speed rotation-high-speed rotation. The wafer rotation speed is 100-500rpm during low-speed rotation, and the wafer rotation speed is greater than 500rpm and less than or equal to 1000rpm during high-speed rotation. The higher the rotation speed, the more charges are generated, so the optimal balance parameters should be found within the adjustment range according to the actual application situation.

3. The method for improving charging effect defects in a compound substrate lithography process according to claim 2, characterized in that: In step (1), the developer flow rate is 400-1000 ml / min, and the total spraying time is 20-80 s.

4. The method for improving charging effect defects in a compound substrate lithography process according to claim 1, characterized in that: In step (2), the speed of high-speed water washing of the wafer is 800-1500rpm, and the time of a single high-speed water washing is 10-60s; the speed of low-speed water washing of the wafer is 100-500rpm, and the time of low-speed water washing is 10-60s.

5. The method for improving charging effect defects in a compound substrate lithography process according to claim 4, characterized in that: In step (2), the flow rate of deionized water is 500-1500 ml / min.

6. The method for improving charging effect defects in a compound substrate lithography process according to claim 1, characterized in that: In step (3), the low-speed rotation speed of the wafer is 300-1000 r / min, the high-speed rotation speed is greater than 1000 r / min and less than or equal to 2000 r / min, and the low-speed and high-speed rotation times of the wafer are both 10-30 s.

7. The method for improving charging effect defects in a compound substrate photolithography process according to claim 1, characterized in that: The wafer is a wafer made of compound semiconductor material.

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