Method for reinforcing a thinned wafer during the process of spin coating

Abstract

The application discloses a reinforcing treatment method of a thinned wafer in a glue uniformizing process, step 1, a wafer is prepared into a wafer sheet through thinning; step 2, a prepared wafer sheet is placed with a surface needing glue uniformizing facing a vacuum suction plate, after vacuum suction, a blue film is uniformly pasted on the back of the wafer sheet, the vacuum is closed, and the wafer sheet with the blue film is taken down; step 3, the obtained wafer sheet with the blue film is placed on a vacuum loading platform of a glue uniformizing machine, the vacuum is opened, and the wafer sheet with the blue film is fixed; step 4, a recipe is set to carry out a glue uniformizing process; step 5, after the glue uniformizing, the vacuum is closed, the wafer sheet with the blue film is placed on a hot plate to be baked; step 6, after baking, the wafer sheet with the blue film is placed with a glue uniformizing surface facing a vacuum plate, vacuum is drawn, after the wafer is fixed, the blue film on the back of the wafer is removed, the wafer is taken down, and the glue uniformizing process is completed; the problem that a wafer is easily broken in a glue uniformizing process when the wafer is thinned to a thickness of 50-200 mu m is solved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of semiconductor lithography, and relates to a reinforcing treatment method for a thinned wafer in a spin coating process. BACKGROUND

[0002] In a compound semiconductor chip manufacturing process, various circuit patterns are copied on a wafer surface through photolithography, which is a key and indispensable means in the field of semiconductors today. The main step is to form a film layer on the wafer surface through spin coating, photolithography, and development. The spin coating on the wafer surface is achieved by directly fixing the wafer on a high-speed rotating stage through a vacuum method. Generally, a wafer with a conventional thickness can be directly prepared into a film layer using this method. However, the above conventional method has certain limitations. In the design and manufacturing process of many chips on the market, double-sided patterns need to be prepared after thinning. The above conventional method cannot achieve the spin coating process of the thinned wafer, and often causes the wafer to break, thereby greatly reducing the yield of the product, and sometimes even cannot perform the process, becoming a technical barrier. The present application proposes a new reinforcing treatment method to complete the spin coating process of the wafer. When the compound wafer is thinned to less than 200 μm, it is very easy to break because it has one or more crystal directions, and is particularly easy to break under external force in the crystal direction. This method fixes the wafer by means of a blue film to disperse the force received by the wafer, and then realizes the spin coating process by means of a vacuum suction plate as a support. SUMMARY

[0003] The purpose of the present application is to provide a reinforcing treatment method for a thinned wafer in a spin coating process, which solves the problem that the wafer is easily broken in the spin coating process when the wafer is thinned to a thickness of 50 μm to 200 μm.

[0004] The technical solution adopted by the present application is a reinforcing treatment method for a thinned wafer in a spin coating process, which is implemented according to the following steps:

[0005] Step 1, preparing a wafer into a wafer sheet through thinning;

[0006] Step 2, placing the wafer sheet prepared in step 1 with the surface needing spin coating facing the vacuum suction plate, and placing a blue film on the back of the wafer sheet after vacuum suction, then closing the vacuum and taking out the wafer with the blue film;

[0007] Step 3, placing the wafer with the blue film obtained in step 2 on the vacuum stage of a spin coater, opening the vacuum, and fixing the wafer with the blue film;

[0008] Step 4, setting a recipe to perform the spin coating process;

[0009] Step 5, after the uniform glue, turn off the vacuum, place the wafer with blue film on the hot plate to bake;

[0010] Step 6, after baking, place the wafer with blue film on the uniform glue surface opposite the vacuum plate, vacuumize, after fixing the wafer, remove the blue film on the back of the wafer, take off the wafer, and complete the uniform glue process.

[0011] The present application is also characterized in that:

[0012] The size of the wafer in step 1 is not greater than Φ4", and the thickness of the wafer is not less than 50μm;

[0013] The vacuum degree of the vacuum suction plate in step 2 is-55kpa~-70kpa;

[0014] In step 3, the blue film on the wafer is cut into a shape greater than 2cm in diameter before placing the wafer on the vacuum stage, and the opened vacuum is-55kpa~-70kpa;

[0015] In step 4, the recipe speed is set from low to high, and then from high to low, and the highest speed is not more than 6000rpm;

[0016] In step 5, the baking temperature is 80℃~100℃, and the baking time is 30s~90s.

[0017] The present application has the advantages of

[0018] The present application provides a new way: to realize the thinning of the wafer in the process of backside lithography, how to carry out the technical means of uniform glue, such as: in order to realize the backside lithography of the wafer of INP compound with a thickness of 100 microns, the pattern is made after the thinning of the wafer, in order to achieve the purpose of backside opening, without changing the process conditions, by means of blue film bonding instead of vacuum suction, the regular or irregular wafer with a thickness of not less than 50μm and Φ4" (including Φ4") is reinforced and treated, and the uniform glue process is completed under the premise of ensuring that the wafer does not break. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is the reinforcing treatment method of the wafer in the uniform glue process of the present application. DETAILED DESCRIPTION

[0020] The present application will be described in detail below in combination with the drawings and specific embodiments.

[0021] The present application provides a reinforcing treatment method of the wafer in the uniform glue process, which is implemented according to the following steps:

[0022] Step 1, regular or irregular wafers with a size not greater than Φ4" are prepared into thin wafer slices with a thickness not less than 50 μm through thinning;

[0023] Step 2, the wafer of Step 1 is placed flat on a vacuum suction plate with the surface needing to be uniformly coated facing downward, after vacuum suction at a vacuum degree of -55 kpa to -70 kpa, a blue film is cut into a shape with a diameter greater than that of the wafer by about 2 cm, the blue film is uniformly attached to the back of the wafer by manual operation with the aid of a flat cotton swab, then the vacuum is closed, and the wafer with the blue film is taken off, as shown in Figure 1

[0024] Step 3, after Step 2 is completed, the wafer is placed on a vacuum loading platform of a spin coater, the vacuum is turned on, and the wafer is fixed;

[0025] Step 4, after Step 3 is completed, a recipe is set, the rotation speed is set from low to high and then from high to low, and the highest rotation speed is not greater than 6000 rpm, and the spin coating process is performed;

[0026] Step 5, after Step 4 is completed, the vacuum is turned off, the wafer is taken off, and is directly placed on a hot plate for baking at a temperature of 80℃ to 100℃ for 30 s to 90 s, and after the process is completed, the wafer is taken off;

[0027] Step 6, after Step 5 is completed, the wafer with the blue film is placed on a vacuum plate with the spin coating surface facing downward, vacuum is drawn, the wafer is fixed, the blue film on the back is manually and slowly torn off, and then the wafer is taken off, thereby completing the spin coating process.

[0028] Example 1

[0029] A reinforcing treatment method for a thinned wafer in a spin coating process specifically includes:

[0030] Step 1, regular wafers with a size of Φ2" are prepared into thin wafer slices with a thickness of 100 μm through thinning;

[0031] Step 2, the wafer of Step 1 is placed flat on a vacuum suction plate with the surface needing to be uniformly coated facing downward, after vacuum suction at a vacuum degree of -70 kpa, a blue film is cut into a circular shape with a diameter greater than that of the wafer by about 2 cm, the blue film is uniformly attached to the back of the wafer by manual operation with the aid of a flat cotton swab, then the vacuum is closed, and the wafer with the blue film is taken off;

[0032] Step 3, after Step 2 is completed, the wafer is placed on a vacuum loading platform of a spin coater, the vacuum is turned on at a vacuum degree of -60 kpa, and the wafer is fixed;

[0033] Step 4, after Step 3 is completed, a recipe is set as shown in Table 1, and the spin coating process is completed;

[0034] Table 1 ​

[0035] Step acceleration rad / s 2 ]] Rpm Time / s 1 5000 200 3 2 5000 1000 3 3 5000 3000 30 4 5000 1000 3 5 5000 200 3 6 5000 0 0

[0036] Step 5, after completing step 4, turn off the vacuum, take the wafer off and directly place it on the hot plate for baking, temperature 90°C, baking time 90s, after completing the process, take the wafer off;

[0037] Step 6, after completing step 5, place the wafer with the blue film on the vacuum plate with the spin coating surface facing down, vacuumize, after fixing the wafer, manually and slowly tear off the blue film on the back, then take the wafer off, which completes the spin coating process.

[0038] Example 2

[0039] The method for reinforcing the thinned wafer during the spin coating process specifically includes:

[0040] Step 1, a broken wafer with a size of Φ3" is thinned to prepare a thin wafer with a thickness of 150μm;

[0041] Step 2, place the wafer in step 1 with the surface needing spin coating facing down on the vacuum suction plate, after vacuumizing (-70kpa), cut the blue film into a shape larger than the wafer diameter by about 2cm, then manually and uniformly paste the blue film on the back of the wafer by using a cotton swab, then turn off the vacuum and take the wafer with the blue film off;

[0042] Step 3, after completing step 2, place the wafer on the vacuum stage of the spin coater, turn on the vacuum (-58kpa) and fix the wafer;

[0043] Step 4, after completing step 3, set the recipe as shown in Table 2 and complete the spin coating process;

[0044] Table 2

[0045] Step acceleration rad / s 2 ]]> Rpm Time / s 1 5000 500 3 2 5000 5000 30 5 5000 500 3 6 5000 0 0

[0046] Step 5, after completing step 4, turn off the vacuum, take the wafer off and directly place it on the hot plate for baking, temperature 90°C, baking time 30s, after completing the process, take the wafer off;

[0047] Step 6, after completing step 5, place the wafer with the blue film on the vacuum plate with the spin coating surface facing down, vacuumize, after fixing the wafer, manually and slowly tear off the blue film on the back, then take the wafer off, which completes the spin coating process.

Claims

1. A method for strengthening a thinned wafer during a spin coating process, the method comprising: Specifically, the following steps are implemented: ​ Step 1, the wafer is prepared into a thin wafer by thinning; Step 2, the thin wafer prepared in step 1 is placed with the surface needing to be uniformly coated facing the vacuum suction plate, and after the vacuum is turned on, the blue film is uniformly attached to the back of the thin wafer, the vacuum is turned off, and the wafer with the blue film is taken off; Step 3, the wafer with the blue film obtained in step 2 is placed on the vacuum loading platform of the uniform coating machine, the vacuum is turned on, and the wafer with the blue film is fixed; Step 4, the recipe is set to perform the uniform coating process; Step 5, after the uniform coating, the vacuum is turned off, the wafer with the blue film is placed on the hot plate for baking; Step 6, after the baking is completed, the wafer with the blue film is placed with the uniformly coated surface facing the vacuum suction plate, the vacuum is drawn, the wafer is fixed, the blue film on the back of the wafer is removed, and then the wafer is taken off, completing the uniform coating process; The size of the wafer in step 1 is not greater than Φ4 ", and the thickness of the thin wafer is not less than 50 μm; The vacuum degree of the vacuum suction plate in step 2 is -55 kpa~ -70 kpa; In step 3, the blue film on the wafer is cut into a circle larger than the diameter of the wafer by 2 cm before being placed on the vacuum loading platform of the uniform coating machine, and the turned-on vacuum is within -55 kpa~ -70 kpa; In step 5, the temperature during the baking process is 80℃~100℃, and the baking time is 30s~90s; The wafer is an InP compound wafer; In step 4, the recipe speed is set from low to high, and then from high to low, and the highest speed does not exceed 6000 rpm.

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