Method for fixing mask plate and wafer

Abstract

The invention discloses a method for fixing a mask plate and a wafer, and relates to the technical field of fixation of the mask plate and the wafer, and the method comprises the following steps: finishing alignment of the mask plate and the wafer by using an alignment machine, and keeping a dielectric interval between the mask plate and the wafer; connecting the mask plate and the wafer with electrostatic injection equipment, and performing electrostatic injection; and removing an alignment machine and electrostatic injection equipment, and keeping the mask plate and the wafer to attract each other and be safely fixed. Static electricity is injected into the mask plate and the wafer, the mask plate and the wafer attract each other after being injected with charges for safe fixing, the magnitude of the safe fixing force can be adjusted through the contact area, the positive and negative charge amount and the dielectric distance, and the wafer process requirements at various temperatures can be met.

Description

Technical Field

[0001] The invention relates to the technical field of mask plate and wafer fixing, and in particular to a method for fixing a mask plate and a wafer. Background Art

[0002] After the existing process wafer bonding mask is aligned, it is transferred to the metal sputtering process, such as Figure 1 As shown in 1a and 1b, the mask plate and the wafer need to be fixed by means of tape or soft magnets, which may cause the position of the metal sputtered onto the wafer to shift, thus rendering the wafer scrapped.

[0003] The invention application with application number 202411259683.2 discloses a suction cup for adsorbing wafers, and its scheme includes a sealing strip connected to the second air channel of the base, the mask plate is above the wafer and covers the wafer and the sealing strip, and when the wafer fits with the suction cup and the mask plate, there is a gap between the sealing strip and the mask plate when the second air channel of the base is not inflated, and when inflated, the sealing strip bulges and presses the mask plate to form a sealed chamber between the mask plate and the suction cup. It can be seen from its scheme that it uses gas adsorption to make the wafer and the mask plate fit together, which may have the risk of offset.

[0004] Patent document No. 201922211008.3 discloses a silicon wafer metal mask. The silicon wafer metal mask proposed in the solution has a simple structure, can effectively avoid material accumulation on the substrate, improve product performance, and has strong practicality and good application prospects. However, the metal mask needs to be fixed by means of tape or soft magnets, which has the risk of offset. Summary of the invention

[0005] In view of the above problems, the present invention aims to provide a method for fixing a mask plate and a wafer, by injecting static electricity into the mask plate and the wafer, so that the mask plate and the wafer are fixed without external support.

[0006] The object of the present invention can be achieved by the following technical solution: A method for fixing a mask plate and a wafer, comprising:

[0007] S1. Use an alignment machine to align the mask plate and the wafer, and maintain the dielectric gap between the mask plate and the wafer;

[0008] S2, connecting the mask plate and the wafer to an electrostatic injection device to perform electrostatic injection;

[0009] S3. Remove the alignment machine and electrostatic injection equipment, and keep the mask and wafer attracted to each other and securely fixed.

[0010] As a further solution of the present invention, the mask plate is made of electrostatic glass.

[0011] As a further solution of the present invention, the flatness (TTV) of the electrostatic glass is less than 2 μm.

[0012] As a further solution of the present invention, the safe fixed time in S3 is:

[0013] Process temperature T<430C, safe fixation for at least 30 minutes;

[0014] Process temperature T < 350C, safe fixation for at least 60 minutes;

[0015] The process temperature T is less than 250C and can be safely fixed for at least 120 minutes.

[0016] As a further solution of the present invention, a dielectric is provided between the mask and the wafer.

[0017] As a further solution of the present invention, when the electrostatic injection is performed in S2, a monopolar or multipolar method is adopted.

[0018] As a further solution of the present invention, when the safety fixation is performed in S3, the safety fixation force formula is:

[0019]

[0020] Among them, Q1 and Q2 are the positive and negative charges, is the dielectric distance, r is the contact radius, ε0 and ε r is the dielectric constant of the mask and wafer.

[0021] As a further solution of the present invention, the safety fixing force range is: 1.1N / cm 2 ~1.7N / cm 2 .

[0022] Beneficial effects of the present invention:

[0023] 1. The present invention injects static electricity into the mask plate and the wafer. After the mask plate and the wafer are injected with charges, they attract each other and are securely fixed. The magnitude of the secure fixing force can be adjusted by the contact area, the amount of positive and negative charges, and the dielectric spacing, and can meet the requirements of wafer process use at various temperatures.

[0024] 2. The present invention fixes the mask plate and the wafer by injecting static electricity without the need for other clamping tools, so that the mask plate and the wafer are fixed without the need for external support, thereby reducing the risk of fixed deviation of the mask plate and the wafer during wafer transfer. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the existing mask and wafer fixing structure;

[0026] Figure 2 This is a schematic diagram of electrostatic injection of a mask and a wafer according to the present invention;

[0027] Figure 3 This is a schematic diagram of the safe fixing of power lines according to the present invention. DETAILED DESCRIPTION

[0028] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar symbols throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0029] After the wafer bonding mask is aligned in the existing process, the mask needs to be fixed to the wafer using tape or soft magnets, which poses a risk of offset and increases the scrap rate of the wafer.

[0030] In view of the above problems, the present invention discloses a method for fixing a mask plate and a wafer, the steps comprising:

[0031] S1. Use an alignment machine to align the mask plate and the wafer, and maintain the dielectric gap between the mask plate and the wafer;

[0032] S2, connecting the mask plate and the wafer to an electrostatic injection device to perform electrostatic injection;

[0033] S3. Remove the alignment machine and electrostatic injection equipment, and keep the mask and wafer attracted to each other and securely fixed.

[0034] Example:

[0035] The wafer can be 4 inches, 6 inches, 8 inches or 12 inches in size. The mask plate is made of electrostatic glass. An alignment machine is used to align the mask plate and the wafer to maintain the dielectric gap between the mask plate and the wafer.

[0036] The dielectric spacer between the mask and the wafer may be a dielectric, and the dielectric may be a photoresist coating, etc. The dielectric thickness may be controlled within a range of 380-675 μm, which may satisfy the adjustment of the safety fixing force.

[0037] Keep the dielectric flatness (TTV) < 2μm, and keep the electrostatic glass surface flatness (TTV) < 2μm, so that the electrostatic glass and the wafer form a better fit.

[0038] like Figure 2 As shown, the mask plate and the wafer are connected to the positive and negative electrodes of the electrostatic injection device respectively, and electrostatic injection is performed to accumulate positive and negative charges on the mask plate and the wafer respectively.

[0039] like Figure 2As shown in a and 2b, when electrostatic injection is performed on the mask plate and the wafer, a unipolar or multipolar method can be used. The unipolar method has a simple structure and easy steps, and the multipolar method uses the mask plate and the wafer to quickly and evenly apply force.

[0040] like Figure 3 As shown, the adjustment of the safety fixing force can be determined by combining the amount of positive and negative charges, the dielectric distance and the contact area between the mask and the wafer. The formula is:

[0041]

[0042] Among them, Q1 and Q2 are the positive and negative charges, is the dielectric distance, r is the contact radius, ε0 and ε r is the dielectric constant of the mask and wafer.

[0043] By adjusting the safety fixing force, the safety fixing force is controlled at 1.1N / cm 2 ~1.7N / cm 2 It can meet various process requirements of wafer processing and maintain the safe fixation requirements of the mask and the wafer.

[0044] It has been verified through experiments that the safe fixing time of the mask and the wafer can be achieved: when the process temperature T<430C, they can be safely fixed for at least 30 minutes; when the process temperature T<350C, they can be safely fixed for at least 60 minutes; when the process temperature T<250C, they can be safely fixed for at least 120 minutes; which can meet the temperature and time requirements of the wafer process.

[0045] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

[0046] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

Claims

1. A method for fixing a mask plate and a wafer, characterized in that: include: S1. Use an alignment machine to align the mask plate and the wafer, and maintain the dielectric gap between the mask plate and the wafer; S2, connecting the mask plate and the wafer to an electrostatic injection device to perform electrostatic injection; S3. Remove the alignment machine and electrostatic injection equipment, and keep the mask and wafer attracted to each other and securely fixed.

2. The method for fixing a mask plate to a wafer according to claim 1, characterized in that: The mask plate is made of electrostatic glass.

3. The method for fixing a mask plate to a wafer according to claim 2, characterized in that: The electrostatic glass has a flatness (TTV) of less than 2 μm.

4. The method for fixing a mask plate to a wafer according to claim 1, characterized in that: The safe fixed time in S3 is: Process temperature T<430C, safe fixation for at least 30 minutes; Process temperature T < 350C, safe fixation for at least 60 minutes; The process temperature T is less than 250C and can be safely fixed for at least 120 minutes.

5. The method for fixing a mask plate and a wafer according to claim 1, characterized in that: A dielectric is arranged between the mask and the wafer.

6. The method for fixing a mask plate and a wafer according to claim 1, characterized in that: When electrostatic injection is performed in S2, a monopolar or multipolar method is adopted.

7. The method for fixing a mask plate and a wafer according to claim 1, characterized in that: When the safety is fixed in S3, the safety fixing force formula is: Among them, Q1 and Q2 are the positive and negative charges, is the dielectric distance, r is the contact radius, ε0 and ε r is the dielectric constant of the mask and wafer.

8. The method for fixing a mask plate and a wafer according to claim 7, characterized in that: The safe fixing force range is: 1.1N / cm 2 ~1.7N / cm 2 .

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