TWI390629B - Use of dry film photoresists in through-silicon via applications - Google Patents

Description

Dry film photoresist for use in enamel perforation applications

This invention relates to the use of dry film photoresist in the application of sputum perforation (TSV).

Dry film photoresists have long been used in the manufacture of printed circuit boards (PCBs). For example, WO 2008/004784 A1 discloses a method for manufacturing a printed circuit board and a printed circuit board obtained thereby. The method comprises the steps of: (a) bonding a dry film comprising a photosensitizer to the copper foil, and subsequently exposing and developing the dry film to form a dry film opening for forming a dot circuit; (b) Forming a copper plating layer by electroless or electrolytic plating, and subsequently stripping the dry film other than the copper plating layer, thereby forming a circuit which is a first metal layer; (c) further comprising a photosensitizer a dry film adhered to the dot circuit, and exposing and developing the dry film to form an external circuit; and (d) forming a second metal layer by performing electroless or electrolytic plating, which is used to improve The conductivity of the point circuit and the external circuit.

US 2007/0095466 A1 discloses a method for manufacturing a multilayer printed wiring board by attaching a photosensitive dry film to an interlayer resin insulating layer having a thin film conductive layer, performing light exposure and development to form a plating resist layer and Then, a conductive circuit is formed on the portion not having the plating resist layer, characterized in that the photosensitive dry film has a nitrogen-containing heterocyclic compound layer on any surface thereof.

To date, prior art has not proposed the application of dry film photoresist to packaged integrated circuits.

Due to the trend toward miniaturization, high functionality and installation reliability of electrical/electronic products, three-dimensional (3D) stacked packages have become the focus of attention because they not only provide increased memory capacity but also increase mounting density and utilization efficiency of the mounting area. The advantages. 3D stacked packages are potential solutions for next-generation packaging technologies and are continuing to evolve. The 3D stacked package can shorten the average length of the connection lines, thus dramatically reducing the transistor package density, wafer size and power consumption, and resulting in low production costs. In addition, the 3D stacked package allows different systems to be integrated into a multi-phase substrate.

The Twisted Hole (TSV) technology is a 3D stacked package that is most noticed by those skilled in the art. The TSV technology forms a wafer in which a perforated hole is formed. Therefore, a plurality of types of wafers of this type are physically and electrically connected to each other via the turns of the crucibles. Traditionally, TSV technology has involved a "wet" process in which a liquid photoresist composition is used. US 2008/0079121 A1 discloses a method for forming germanium vias in a semiconductor wafer, comprising the steps of: defining a recess in a wafer, the wafer can form a plurality of semiconductor wafers; applying a liquid polymer Filling the groove on the wafer; forming an insulating layer on the sidewall of the groove by patterning the polymer; forming a metal layer on the sidewall thereof; and polishing the back surface of the wafer to expose A metal layer filled in the recess.

There are several problems with the TSV technology involving the "wet" approach. For example, when a channel or trench of an interconnect is formed during etching, it is difficult to control the depth of the channel or the trench during etching. When the etching is temporarily aborted, the etching destroys the porous yttrium oxide at the bottom of the channel or trench for interconnection, which results in leakage current at the bottom of the channel and a higher dielectric constant. Although the TSV technology involving the "wet" method can form a channel or a trench, this technique does not provide protection for the channel or the trench. In addition, "overloading" often occurs.

The deep RIE method (hereinafter referred to as "DRIE method") is a method of providing a path for channel formation on a wafer. One commonly used DRIE method is the Bosch method. By carefully controlling the etching and passivation conditions, the mask produced by photoresist photolithography etching can be performed under mild conditions. However, some of the photoresists, due to their lack of selectivity during the Bosch process, show undesirable results and channels of poor quality.

There is still a need to develop a TSV method for 3D stacked packages that does not have such problems as described above.

The present invention provides a method for forming germanium vias in a wafer, comprising the steps of: providing a wafer on which a dry film photoresist is laminated, and exposing the dry film photoresist to a mask through a mask a light source to form an unexposed photoresist region and an exposed photoresist region, to develop the dry film photoresist to expose portions of the underlying portions of the unexposed photoresist regions, and to etch the exposed portions of the underlying portions of the wafer using a DRIE method A germanium via is formed in the wafer, and the exposed photoresist regions are removed from the wafer with a photoresist remover. The present invention also provides a method for protecting ruthenium perforations in a wafer, and a method for electroplating ruthenium perforations in a wafer, the features of which are also the use of dry film photoresist.

In one aspect, the present invention provides a method for forming a ruthenium perforation in a wafer, comprising the steps of:

(a1) providing a wafer,

(b1) laminating a dry film photoresist on the wafer,

(c1) exposing the dry film photoresist to a light source through a mask to form an unexposed photoresist region and an exposed photoresist region,

(d1) developing the dry film photoresist to expose portions of the underlying portions of the unexposed photoresist regions,

(e1) dry etching the exposed under portions of the wafer using a DRIE method to form germanium vias in the wafer, and

(f1) removing the exposed photoresist regions from the wafer with a photoresist remover.

In a preferred embodiment of the invention, the dry film photoresist on the wafer is post-developed and baked prior to step (e1). Preferably, the post-development bake is performed by baking the dry film photoresist on the wafer in an oven at a temperature of from about 60 ° C to about 130 ° C for from about 5 minutes to about 30 minutes. Preferably, step (e1) is carried out using a gas such as SF ₆ and C ₄ F ₈ .

In a further aspect, the present invention provides a method of protecting a helium perforation in a wafer, comprising the steps of:

(a2) providing a wafer having a perforated hole,

(b2) plating a metal layer on the wafer,

(c2) laminating a dry film photoresist on the wafer,

(d2) exposing the dry film photoresist to a light source through a mask to form an exposed photoresist region on the channels of the wafer, and forming an unexposed photoresist region on other regions of the wafer,

(e2) developing the dry film photoresist to expose portions of the underlying portions of the unexposed photoresist regions,

(f2) etching the exposed underlying portions of the wafer with an etching solution to protect the germanium vias and form a desired pattern on the wafer, and

(g2) removing the exposed photoresist regions from the wafer with a photoresist remover.

Preferably, step (b2) is performed by depositing a thin metal layer on the wafer and subsequently plating a metal layer on the thin metal layer of the wafer.

Preferably, the back side of the wafer is also formed by laminating a dry film photoresist on the back surface of the wafer and exposing the dry film photoresist to a light source to form an exposed photoresist region on the back surface of the wafer. And protect it.

In still further aspects, the present invention provides a method of ruthenium perforation in an electroplated wafer, comprising the steps of:

(a3) providing a wafer having a perforated hole,

(b3) depositing a thin metal layer on the wafer,

(c3) laminating a dry film photoresist on the thin metal layer of the wafer,

(d3) exposing the dry film photoresist to a light source through a mask to form an unexposed photoresist region on the channels of the wafer, and forming an exposed photoresist region on other regions of the wafer,

(e3) developing the dry film photoresist to expose the channels of the underlying portion of the wafer,

(f3) plating the channel of the wafer with a metal until it is filled, and

(g3) removing the exposed photoresist regions from the wafer with a photoresist remover.

Any wafer that can be used to fabricate electronic components can be used in the present invention. For example, the wafer may be composed of indium tin oxide (ITO) glass, germanium, germanium dioxide, tantalum nitride, GaN, sapphire, InGaN, AlInGaP, or ceramics.

Any known negative dry film photoresist can be used in the method of the present invention. May be used in the present invention include a negative type photosensitive dry film resist of an acrylate; e.g. by EI Du Pont De Nemours and Company manufactured and sold by MPF ^TM series. A EIDu Pont De Nemours and Company of manufacture and sale of such a dry film photoresist, MPF ^TM MX5000 series (15,20,30,40,50 microns thick), MPF ^TM MXA 100 (10,15,25 microns thick) and MPF ^TM WBR2000 preferred system.

Any desired metal can be used in steps (b2), (b3) and (f3). Preferably, the metal is copper.

In steps (c1), (d2) and (d3), the mask may carry any desired pattern. The patterns define areas of the dry film photoresist to be exposed to the light source. The light source may be, for example, infrared light, broadband ultraviolet light, deep ultraviolet light, ultra ultraviolet light, e-light beam, and x-ray.

The steps (d1), (e2) and (e3) are carried out by using an alkaline or neutral developing solution. Any known alkaline or neutral developing solution can be applied to the steps (d1), (e2) and (e3) of the present invention. Preferably, the steps (d1), (e2), and (e3) are carried out using an aqueous alkaline sodium carbonate solution having a concentration of 0.1 to 1.5 v/v%.

In step (e1), the DRIE method is preferably a Bosch method. Preferably, step (e1) is performed using an STS multi-function ASE DRIE etching system under the following conditions (inductively coupled plasma (ICP) source power and bias power are set to 900 W and 15 W, respectively. ICP source for passivation step) The power and partial power are fixed at 800W and 0W, respectively. Step (f2) is carried out using an etching solution, for example, a H ₃ PO ₄ , H ₂ SO ₄ , and CuCl ₂ solution.

Any known plating technique can be used to perform steps (b2) and (f3). For example, steps (b2) and (f3) can be carried out by electrolytic plating, electroless plating, sputtering, or evaporation.

In the step (f1), (g2) and (g3), the photoresist remover based for example EIDu Pont De Nemours and Company and manufactured and sold by EKC162 ^TM EKC265 ^TM.

The method of the present invention makes it easier to control the depth of the channel during the etching step of the TSV technology and to eliminate the "overload" condition that always occurs with the TSV technology involving the "wet" method. The dry film photoresist method of the present invention can be applied to channel formation, channel protection, and channel plating. In contrast to prior art methods in which a liquid photoresist (positive or negative) is used, the dry film photoresist method of the present invention requires a relatively short total processing time.

The invention will be apparent from the following examples, which are intended to be illustrative only and not to limit the scope of the invention described in the claims.

Instance Example 1 - Channel Formation

Materials and procedures:

Six wafers having an area of 100 x 100 mm ^{2 were} prepared for subsequent use. use Laminator as lamination instrument, under the following conditions will be manufactured and sold ^{EIDu Pont De Nemours and Company MPF TM} MX5000 series (15 microns thick) of a dry film resist is laminated on each wafer:

Speed: 1m/min

Pressure: 3kg/cm ²

Temperature: 110 ° C

The dry film photoresist on the wafers is patterned according to the following procedures:

The dry film photoresist on the wafer is exposed by a lithography etch mask using a MA8 Suss locator with a 25.44 mJ/cm ² i-line to form an unexposed photoresist area and exposure. The photoresist area. The wafer was developed using a 0.65% sodium carbonate solution at 26 ° C for 60 seconds. All six wafers were moved into an etch chamber using an STS multi-function ASE DRIE etch system. For this etching step, the inductively coupled plasma (ICP) source power and the bias power were set to 900 W and 15 W, respectively. For the passivation step, the ICP source power and the bias power are set to 800 W and 0 W, respectively. A Zygo interferometer was used as a measurement tool for 20 micron channel depth. Channels having diameters of 10, 20, 30, 40, and 50 microns are formed in each of the six wafers. Three of the wafers were transferred to an oven and developed at 85 ° C for 20 minutes. All 6 wafers were etched with O ₂ for 3 minutes to remove potential development debris.

result:

Cross-sectional SEM images of the wafers that were not post-development baked showed different channel etch depths. For etch times of 16, 33 and 58 minutes, the etch depths of the equal channels having a diameter of 20 microns were 52, 92 and 150 microns, respectively. The results also showed that the dry film thickness loss is not significant, which disclose that MPF ^TM MX5000 series of dry film photoresist (15 microns thick), having a high etch selectivity (i.e., 100: 1) In the Bosch process. The high magnification SEM image shows no "under etching" effect between the wafer and the photoresist.

In the wafer which was dried after development, even etching selectivity was found (see Fig. 1). The resists of both the wafers subjected to development and drying and the wafers which were not subjected to development and drying were well present in the DRIE method.

SEM image shown in FIG. 1 demonstrates that the dry film photoresist MPF ^TM MX5000 series (15 m thick) The results obtained after the lithography, the photoresist dry film system having an uncoated 50 micron diameter of the passage in which Apply the wafer.

The SEM image shown in Figure 2 demonstrates the results obtained after the 58 minute eclipse cycle, which results in a high vertical sidewall.

The SEM images shown in Figures 3, 4 and 5 demonstrate the results obtained after three, etch cycles, i.e., 16 , 33 and 58 minutes, respectively.

Example 2 - Channel Protection for Filled and Unfilled Channels

Wafers having channels having diameters ranging from 10 microns to 250 microns are prepared. A 2 μm thin metal layer was deposited on each wafer, and then a 10 μm metal layer was plated on the entire surface of the upper side of the wafer. The dry film photoresist is evaluated for channel protection of unfilled metallization channels and metal filled channels on the wafer in the following manner.

1. Protection of unfilled channels

The procedure according to Example 1, the EIDu Pont De Nemours and Company manufactured and sold by MPF ^TM MX5000 series (15 m thick) laminated dry film photoresist on the wafer, but using the conditions shown in Table 1 below:

After lamination, the wafers having dry film photoresist on the vias are subjected to a photolithographic etching process using a mask having a dog bone structure. The wafers are exposed through the mask using a MA8 Suss positioner with a 25.44 mJ/cm ² i-line to form an exposed photoresist region on the channels of the wafers and on the wafer. Unexposed photoresist regions are formed on other regions. The wafers were developed using a 0.65% sodium carbonate solution at 26 ° C for 60 seconds. Subsequently, the wafers were transferred to an oven at 80 ° C for development and baked for 10 minutes.

The test was performed using a mask having a dog bone configuration using the exposure, development and etching steps of Example 1. Obtain a cross-sectional SEM picture of the wafer with the channel. The use of dry film photoresist in TSV applications demonstrates the unique "masking" capability on the pre-exit channel on the wafer during lamination without failure. Moreover, even if the channels have a diameter as large as 200 microns, the dry film photoresist on the unfilled channels of the wafers protects the channels from being etched during subsequent etching steps.

result:

6 and FIG. 7 of the SEM photograph shown in the display by using a hot roll lamination of the dry film resist obtained MPF ^TM MX5000 series (15 microns thick) of the "cover" capability. No cover failure was observed.

The SEM image shown in Figure 8 shows the wafer after the lithography process using a mask having a dog bone structure.

The SEM images shown in Figures 9 and 10 show wafers derived from the "covering" residual experiment. The dry film photoresist EVEN MPF ^TM MX5000 series (15 microns thick) not fully compatible with the metal etch chemistry, and has a strong "cover" resistance, even when a higher than normal undercut. In addition, no residue was observed in the channels or on the surface of the wafers after the dry film photoresist was removed.

2. Fill channel protection

Using the same procedure as for the protection of the unfilled channel, to a dry film photoresist MPF ^TM MX5000 series (15 microns thick) is protected completely fill the channel in this test of the wafers. In this test, a dry film photoresist MPF ^TM MX5000 series (15 microns thick) also provide a good protection for the other channel is completely filled wafer, and the failure was not observed during the etch dry film photoresist removal step.

in conclusion:

The dry film photoresist MPF ^TM MX5000 series (15 micron thick) is one of the 3D TSV applications due to its unique dry film properties during the Bosch process, including easy processing, uniform thickness, high throughput and excellent selectivity. Excellent photoresist replacement. Using a dry film photoresist MPF ^TM MX5000 series (15 microns thick) formed of the result of channel, display high selectivity (i.e., 100: 1), yet, no significant thickness loss after the Bosch process. In addition, the dry film photoresist MPF ^TM MX5000 series (15 microns thick) to be readily removed without any residue on the wafer surface, or such passage. In this channel protection test results are shown using a dry film photoresist MPF ^TM MX5000 series (15 microns thick) obtained cleaning the developing characteristics and strong hiding power. No development residue and cracked cover channels were found after the process.

Example 3 - Channel Plating

A tantalum wafer having a 50 micron diameter channel was prepared. The wafer is channel insulated to deposit an oxide layer (via CVD) having a thickness of 600 nm on the wafer, and then a 200 nm nitride layer (LPCVD) is formed on the oxide layer. The wafer was then subjected to seed precipitation to form a Ti layer having a thickness of 0.1 μm on the wafer followed by deposition of a 3 pm thick Cu layer. Thereafter, the procedure according to Example 1, the fabricated from EIDu Pont De Nemours and Company and marketed MPF ^TM MX5000 series (15 m thick) laminated on the dry film resist the wafers, but using the following conditions:

Machine: Leonardo-Laminating Tools,

Chuck temperature: 80 ° C,

Roller temperature: 20 ° C, and

Knife temperature: 120 ° C.

After lamination, the MA6 hand tool exposed the wafer at an exposure level of 36 mJ/cm ² . The wafer is then developed under the following conditions:

Machine: S ssACS200 ^TM ,

Reagent: buffered 0.65% K ₂ CO ₃ (trade name: D4000),

Temperature: 28°C for pattern plating applications

Development time: 50 seconds, and

Washing time: 10 seconds (water artificially hardened with MgSO ₄ ).

After development, the wafer was plated for 2 minutes using 400 W/O ₂ flash plasma, followed by pickling for 1 minute. The plating speed was 2 μm/min.

Example 4 - Yield Comparison

Comparison of Yield based method of the present invention to two prior art methods, the present invention is a method using a dry film photoresist MPF ^TM MX5000 series (15 microns thick), the prior art using a liquid positive photoresist (manufactured by AZ Chemical Company and marketed AZ4620 ^TM ) and liquid negative photoresist (THB series ^TM manufactured and sold by JSR). The results of this comparison are shown in Table 2 below:

As shown in the above table, there are two prior art methods compared to the use of liquid positive photoresist (AZ4620 ^TM manufactured and sold by AZ Chemical Co., Ltd.) and liquid negative photoresist (THB series ^TM manufactured and sold by JSR Corporation). using the MPF ^TM MX5000 series (15 microns thick) of a dry film resist method of the present invention requires a relatively short total treatment time.

The SEM image shown in FIG. 1, shows the results obtained after the dry film photoresist MPF ^TM MX5000 series (15 microns thick) of the lithography process, the dry film photoresist-based channel added unloaded having a diameter of 50 microns On the wafer.

The SEM image shown in Figure 2 shows the results obtained after a 58 minute etch cycle.

The SEM images shown in Figures 3, 4 and 5 show the results obtained after an etch cycle of 16 minutes, 33 minutes, and 58 minutes, respectively.

SEM images shown in FIG. 6 of 7, the dry film photoresist MPF ^TM MX5000 series (15 microns thick) of "covering (tenting)" capability, which system is obtained by using a hot roll laminator.

The SEM image shown in Fig. 8 shows the wafer after the lithography process using a mask having a dog bone structure.

The SEM images shown in Figures 9 and 10 show wafers obtained from a "cover" residual experiment.

(no component symbol description)

Claims (16)

A method for protecting a ruthenium perforation in a wafer, comprising the steps of: (a2) providing a wafer having a ruthenium perforation, (b2) plating a metal layer on the wafer, and (c2) plating the wafer Laminating a dry film photoresist, (d2) exposing the dry film photoresist to a light source through a mask to form an exposed photoresist region on the plurality of channels of the wafer, and forming an unmasked region on other regions of the wafer Exposing the photoresist region, (e2) developing the dry film photoresist to expose the underlying portions of the unexposed photoresist regions, and (f2) etching the exposed bottom portions of the wafer with an etching solution to protect the portions矽perforating, and forming a desired pattern on the wafer, and (g2) removing the exposed photoresist regions from the wafer with a photoresist removal agent. The method of claim 1, wherein the wafer is composed of indium tin oxide (ITO) glass, germanium, hafnium oxide, tantalum nitride, GaN, sapphire, InGaN, AlInGaP, or ceramics. The method of claim 1, wherein the metal is copper in the step (b2). The method of claim 1, wherein the step (b2) is performed by depositing a thin metal layer on the wafer and subsequently plating a metal layer on the thin metal layer of the wafer. The method of claim 1, wherein the dry film photoresist in step (c2) comprises a negative dry film photoresist of a photosensitive acrylate. The method of claim 1, wherein the light source in the step (d2) is infrared light, broadband ultraviolet light, deep ultraviolet light, ultra ultraviolet light, e-light beam or x-ray. The method of claim 1, wherein an aqueous alkaline sodium carbonate solution having a concentration of 0.1 to 1.5 v/v% is used in the step (e2). The method of claim 1, wherein the step (f2) is performed with an etching solution. The method of claim 1, wherein the back side of the wafer is also protected. The method of claim 9, wherein the back side of the wafer is formed by laminating a dry film photoresist on the back side of the wafer, and exposing the dry film photoresist to a light source to form an exposure on the back surface of the wafer. Protected by the photoresist area. A method for etching a ruthenium in a wafer, comprising the steps of: (a3) providing a wafer having a ruthenium perforation, (b3) depositing a thin metal layer on the wafer, and (c3) depositing the wafer Laminating a thin film of photoresist on the thin metal layer, (d3) exposing the dry film photoresist to a light source through a mask to form an unexposed photoresist region on the plurality of channels of the wafer and on the wafer Forming an exposed photoresist region on other regions, (e3) developing the dry film photoresist to expose the underlying portions of the wafer, and (f3) plating the channels of the wafer with a metal until it is Filling, and (g3) removing the exposed photoresist regions from the wafer with a photoresist remover. The method of claim 11, wherein the wafer is made of indium tin oxide (ITO) glass, germanium, germanium dioxide, tantalum nitride, GaN, sapphire, InGaN, Made up of AlInGaP, or pottery. The method of claim 11, wherein the metal is copper in steps (b3) and (f3). The method of claim 11, wherein the dry film photoresist in step (c3) comprises a negative dry film photoresist of a photosensitive acrylate. The method of claim 11, wherein the light source in the step (d3) is infrared light, broadband ultraviolet light, deep ultraviolet light, ultra ultraviolet light, e-light beam or x-ray. The method of claim 11, wherein an aqueous alkaline sodium carbonate solution having a concentration of 0.1 to 1.5 v/v% is used in the step (e3).