A method for completely cleaning the die separation tape from the die surface

Abstract

The present invention relates to a method (100) for completely removing the die separation tape from the surface of a MEMS / NEMS chip (die) or of a wafer containing multiple MEMS / NEMS chips together by applying dry etching process with oxygen plasma, without performing any wet etching process or wet cleaning process.

Description

[0001] A METHOD FOR COMPLETELY CLEANING THE DIE SEPARATION TAPE FROM THE DIE SURFACE

[0002] Technical Field

[0003] The present invention relates to a method for completely removing the die separation tape from the surface of a MEMS / NEMS chip (die) or of a wafer containing multiple MEMS / NEMS chips together by applying dry etching process with oxygen plasma, without performing any wet etching process or wet cleaning process.

[0004] Background of the Invention

[0005] The adhesion behavior of the die separation tape onto the die surface varies depending on the surface quality of the die and the type of coating material on the die. In a study, the upper layer on the Pyrex substrate surface with MEMS chips was coated with alumina deposited by the atomic layer deposition method. The alumina (AI2O3) layer coated by the atomic layer deposition method was etched uncontrollably from some areas of the Pyrex substrate (mostly from the substrate edges) due to microfabrication processes. A UV (ultraviolet) light-curable, highly adhesive dicing saw tape with a thickness of 150 microns was used to singulate (i.e., to form single dies) MEMS device chips by cutting them with a dicing saw from a full-size Pyrex wafer. Despite being exposed to sufficient UV light, the highly adhesive dicing tape could not be removed from the surface of several MEMS dies where there was no alumina layer on the Pyrex wafer. However, for the remaining processes of characterization, integration or obtaining prototype MEMS products, the cutting tape needs to be properly separated or cleaned from the MEMS die so as to obtain MEMS dies. Furthermore, since MEMS dies are very sensitive or have no resistance to wet processes after certain process steps are completed, or to mechanical tensile forces applied during mechanical peeling of the cutting tape from the MEMS device, dry etching method with oxygen plasma is of critical importance to remove (clean, eliminate, etch) the cutting tape without damaging the mechanical or electromechanical parts. In addition, due to the potential sensitivity of the mechanical or electromechanical structures, such as membranes or springs, which have mobility, in some MEMS or some NEMS dies, to the mechanical tensile forces that are ordinarily applied during the mechanical peeling of such cutting tapes from the surface, it is certainly not preferred to peel the separation tape from such sensitive surfaces by mechanical tensile force. Cleaning methods that do not require applying large amounts of mechanical tensile force and do not require processing in a wet environment will definitely be preferred in priority. For this reason, there is a need for a new method for completely cleaning the die separation tape from the die surface without performing any wet etching process or wet cleaning process.

[0006] The Chinese patent document no. CN115663074, an application included in the state of the art, discloses an LED chip and a manufacturing method of the LED chip. The manufacturing method of the LED chip comprises steps of polishing, wet washing, photoetching, ion implantation, etching, plasma flushing, heat treatment, chemical vapor deposition, physical vapor deposition, electroplating treatment, surface treatment and test packaging. Platinum-titanium mesh material is used for electroplating, and platinum-titanium mesh material is used for surface treatment. The etching comprises dry etching and wet etching. In the dry etching, unwanted shapes obtained through photoetching are washed away through plasma, in the wet etching, the silicon wafer is further cleaned through a reagent. After residual impurities and photoresist on the surface of the silicon wafer are peeled off, the silicon wafer is removed through the reagent. The surface of the silicon wafer is repeatedly cleaned, and after electroplating is completed, residual impurities and photoresist on the surface of the silicon wafer are stripped again, so that the phenomena that a front bonding wire is difficult to be in pseudo soldering or a back surface causes high voltage drop, and breakdown and the like are avoided. Summary of the Invention

[0007] The objective of the present invention is to realize a method to completely remove the die separation tape from the surface of a MEMS chip or of a wafer containing multiple MEMS chips together by applying dry etching process with oxygen plasma, without performing any wet etching process or wet cleaning process.

[0008] Detailed Description of the Invention

[0009] “A Method for Completely Cleaning the Die Separation Tape from the Die Surface” realized to fulfil the objectives of the present invention is shown in the figures attached, in which:

[0010] Figure 1 is a flowchart of the inventive method.

[0011] The components illustrated in the figures are individually numbered, where the numbers refer to the following:

[0012] 100. Method

[0013] The inventive method for completely removing the die separation tape from the surface of a MEMS / NEMS chip or of a wafer containing multiple MEMS / NEMS chips together by applying dry etching process with oxygen plasma, without performing any wet etching process or wet cleaning process comprises the steps of exposing the surface of a MEMS / NEMS chip or a wafer containing multiple MEMS / NEMS chips together to UV light, where the dicing (cutting) tape is present (101); removing the surface of a MEMS / NEMS chip or a wafer containing multiple MEMS / NEMS chips together, where the dicing tape is present and which is exposed to UV light, by means of etching by applying the oxygen plasma dry etching process (102); peeling off the tape residue remaining on the surface of the chip / wafer by pulling it off by means of a low-adhesive cutting tape that does not need to be cured by UV light, after having largely, but still partially, etched the cutting tape off the MEMS / NEMS chip or wafer containing multiple MEMS / NEMS chips together by plasma dry etching process (103); completely clearing the chip / wafer from the cutting tape by applying the oxygen plasma dry etching process again in order to remove the cutting tape residues initially found on the surface of the MEMS / NEMS chip or wafer containing multiple MEMS / NEMS chips together and, if any, the low- adhesive cutting tape residues applied at step 103 from the chip / wafer surface (104).

[0014] At the step of exposing the surface of a MEMS / NEMS chip or a wafer containing multiple MEMS / NEMS chips together to UV light, where the dicing (cutting) tape is present (101) of the inventive method (100), a 1200 mJ / cm2UV ray is applied to the dicing tape coded Adwill D-841.

[0015] At the step of removing the surface of a MEMS / NEMS chip or a wafer containing multiple MEMS / NEMS chips together, where the dicing tape is present and which is exposed to UV light, by means of etching by applying the oxygen plasma dry etching process (102) of the inventive method (100), the UV ray applied MEMS / NEMS chip / wafer surface is etched by applying oxygen plasma dry etching process in an inductively coupled plasma (ICP) device for 1-5 hours. The duration of this etching process is related to the thickness of the dicing tape and the chemical structure of the materials in the dicing tape and varies for different dicing tapes.

[0016] At the step of peeling off the tape residue remaining on the surface of the chip / wafer by pulling it off by means of a low-adhesive cutting tape that does not need to be cured by UV light, after having largely, but still partially, etched the cutting tape off the MEMS / NEMS chip or wafer containing multiple MEMS / NEMS chips together by plasma dry etching process (103) of the inventive method (100), the residues of the cutting tape materials on the MEMS / NEMS chip / wafer that cannot be removed by oxygen plasma process are peeled off by being pulled off from the surface with the help of a low-adhesive T-80HW-23A, a cutting tape that does not need to be cured by UV light.

[0017] At the step of completely clearing the chip / wafer from the cutting tape by applying the oxygen plasma dry etching process again in order to remove the cutting tape residues initially found on the surface of the MEMS / NEMS chip or wafer containing multiple MEMS / NEMS chips together and, if any, the low-adhesive cutting tape residues applied at step 103 from the chip / wafer surface (104) of the inventive method (100), the oxygen plasma dry etching process in an inductively coupled plasma device is applied again for 15-45 minutes in order to remove the residues of the T-80HW-23A tape and the very small amount of bottom residues remaining from the Adwill D-841 tape from the MEMS / NEMS chip / wafer surface, and the MEMS / NEMS chip / wafer surface is completely cleaned without the need for any wet etching process.

[0018] The oxygen plasma dry etching process (descum process) is used to etch a very large portion of the cutting tape used to separate the wafers into MEMS / NEMS dies that is initially located on the MEMS / NEMS dies, and then the small amount of residues remaining on the MEMS / NEMS dies. The parameters of the etching process with oxygen plasma used to etch the cutting tape are given in Table 1. It includes all the technical process details required to effectively use and repeat the dicing tape etching process with oxygen plasma, without being limited by the specified process parameters.

[0019] Table 1. Parameters of the etching process with oxygen plasma used to etch the cutting tape

[0020] Industrial Application of the Invention

[0021] Although the inventive method (100) can be applied to chips that have already been singulated as chips, it can also be applied when the dies are still in array and collectively connected to the separation tape, if needed. The fact that these processes can also be applied while the dies are still in array on the separation tape in full wafer size and collectively connected to the separation tape (but the dies are still geometrically separated from each other) makes this cleaning process even more valuable. In order to completely clean the separation tape from the surface when it is in full wafer size, by placing a carrier wafer under the wafer containing the MEMS / NEMS structures, the actual wafer can be processed in a reactor chamber that performs oxygen plasma process on this carrier wafer. With this method, the uncontrolled dispersion of MEMS / NEMS or NEMS / NEMS chips, which will be free after cleaning the cutting tape, into the process reactor is prevented. Furthermore, this entire approach can be used not only for dicing tapes whose adhesive properties are weakened by UV radiation, but also for dicing tapes that do not require UV radiation to be removed or cleaned from the surface of a MEMS / NEMS device without the need for high magnitude of mechanical force and wet etching.

[0022] Within these basic concepts; it is possible to develop various embodiments of the inventive “A Method (100) for Completely Cleaning the Die Separation Tape from the Die Surface”; the invention cannot be limited to examples disclosed herein and 5 it is essentially according to claims.

Claims

CLAIMS1. A method (100) for completely removing the die separation tape from the surface of a MEMS / NEMS chip or of a wafer containing multiple MEMS / NEMS chips together by applying dry etching process with oxygen plasma, without performing any wet etching process or wet cleaning process; characterized in that it comprises the steps of; exposing the surface of a MEMS / NEMS chip or a wafer containing multiple MEMS / NEMS chips together to UV light, where the dicing (cutting) tape is present (101); removing the surface of a MEMS / NEMS chip or a wafer containing multiple MEMS / NEMS chips together, where the dicing tape is present and which is exposed to UV light, by means of etching by applying the oxygen plasma dry etching process (102); peeling off the tape residue remaining on the surface of the chip / wafer by pulling it off by means of a low-adhesive cutting tape that does not need to be cured by UV light, after having largely, but still partially, etched the cutting tape off the MEMS / NEMS chip or wafer containing multiple MEMS / NEMS chips together by plasma dry etching process (103); completely clearing the chip / wafer from the cutting tape by applying the oxygen plasma dry etching process again in order to remove the cutting tape residues initially found on the surface of the MEMS / NEMS chip or wafer containing multiple MEMS / NEMS chips together and, if any, the low- adhesive cutting tape residues applied at step 103 from the chip / wafer surface (104).

2. A method (100) according to Claim 1; characterized in that at step of exposing the surface of a MEMS / NEMS chip or a wafer containing multiple MEMS / NEMS chips together to UV light, where the dicing (cutting) tape is present (101), 1200 mJ / cm2UV ray is applied to the dicing tape coded Adwill D-841.

3. A method (100) according to Claim 1 or 2; characterized in that at step of removing the surface of a MEMS / NEMS chip or a wafer containing multiple MEMS / NEMS chips together, where the dicing tape is present and which is exposed to UV light, by means of etching by applying the oxygen plasma dry etching process (102), the UV ray applied MEMS / NEMS chip / wafer surface is etched by applying oxygen plasma dry etching process in an inductively coupled plasma (TCP) tool for 1-5 hours.

4. A method (100) according to any one of the preceding claims; characterized in that at step of peeling off the tape residue remaining on the surface of the chip / wafer by pulling it off by means of a low-adhesive cutting tape that does not need to be cured by UV light, after having largely, but still partially, etched the cutting tape off the MEMS / NEMS chip or wafer containing multiple MEMS / NEMS chips together by plasma dry etching process (103), the residues of the cutting tape materials on the MEMS / NEMS chip / wafer that cannot be removed by oxygen plasma process are peeled off by being pulled off from the surface with the help of a low-adhesive T-80HW-23A, a cutting tape that does not need to be cured by UV light.

5. A method (100) according to any one of the preceding claims; characterized in that at step of completely clearing the chip / wafer from the cutting tape by applying the oxygen plasma dry etching process again in order to remove the cutting tape residues initially found on the surface of the MEMS / NEMS chip or wafer containing multiple MEMS / NEMS chips together and, if any, the low- adhesive cutting tape residues applied at step 103 from the chip / wafer surface (104), the oxygen plasma dry etching process in an inductively coupled plasma device is applied again for 15-45 minutes in order to remove the residues of the T-80HW- 23 A tape and the very small amount of bottom residues remaining from the Adwill D-841 tape from the MEMS / NEMS chip / wafer surface, and the MEMS / NEMSchip / wafer surface is completely cleaned without the need for any wet etching 5 process.

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