TWM649373U - Non-contact wafer surface particle removing device - Google Patents

Abstract

A non-contact wafer surface particle removal device is used to remove particles on a wafer surface to be cleaned, and includes a reaction chamber, a plasma chamber, an induction coil and a bias generating device. The reaction chamber has an accommodating space for accommodating the wafer to be cleaned. The plasma chamber is coupled to a top of the reaction chamber; there is a remote plasma space inside the plasma chamber that is connected to the accommodation space. The induction coil surrounds the plasma cavity and is used to provide a time-varying magnetic flux to the remote plasma space to induce an electric field, so that a working gas located in the remote plasma space is ionized to generate a remote plasma. The bias voltage generating device is used to generate a bias electric field that changes with time in the reaction chamber, so that the working gas located in the reaction chamber is liberated into a proximal plasma.

Description

Non-contact wafer surface particle removal device

The present invention relates to the cleaning of wafers, in particular to a non-contact wafer surface particle removal device used to remove carbon particles precipitated on the surface of SiC wafers.

As shown in Figure 1, it is the existing BGBM process (Backside Grinding & Backside Metallization, back grinding and back metallization). As shown in part (A) of Figure 1, the SiC wafer 1 is first temporarily bonded or bonded to the carrier 2 with the front side (the downward part in the picture), and the carrier 2 is used to increase the mechanical strength of the SiC wafer 1. strength to prevent the SiC wafer 1 from warping or breaking during the grinding process. The back side of the SiC wafer 1 (the upward part in the figure) will be coated to form a metal film 3, as shown in part (B) of Figure 1 . Next, a laser annealing process is performed on the metal film 3. The annealing process causes a chemical reaction between the silicon atoms in the SiC wafer 1 and the nickel atoms in the metal film 3 to form nickel silicide to form an ohmic contact structure, Figure 1 As shown in part (C).

Finally, a metal layer is grown on the metal film 3 to form a back metal layer 4. As shown in part (D) of Figure 1, the BGBM process is completed.

However, referring to parts (C) and (D) of FIG. 1 , the formation of nickel silicide will cause the carbon particles 5 in SiC to precipitate and gradually accumulate on the surface of the metal film 3 . After the back metal layer 4 is formed. The presence of carbon particles 5 weakens the bond between the back metal layer 4 and the metal film 3 . Therefore, in subsequent processing projects During the process, the back metal layer 4 is easily peeled off from the surface of the metal film 3, resulting in defective products, as shown in part (E) of Figure 1 .

In view of the above technical problems, this new model proposes a non-contact wafer surface particle removal device for cleaning the SiC wafer surface to avoid carbon precipitation or other unnecessary compounds remaining on the SiC wafer surface, and to avoid subsequent processing of the back metal layer from being affected. Force falls off.

The present invention proposes a non-contact wafer surface particle removal device for removing particles on a wafer surface to be cleaned, which includes a reaction chamber, a plasma chamber, an induction coil and a bias generating device. The reaction chamber has an accommodating space for accommodating the wafer to be cleaned. The plasma chamber is coupled to a top of the reaction chamber; there is a remote plasma space inside the plasma chamber that is connected to the accommodation space. The induction coil surrounds the plasma cavity and is used to provide a time-varying magnetic flux to the remote plasma space to induce an electric field, so that a working gas located in the remote plasma space is ionized to generate a remote plasma. The bias voltage generating device is used to generate a bias electric field that changes with time in the reaction chamber, so that the working gas located in the reaction chamber is liberated into a proximal plasma.

In at least one embodiment, a top of the reaction chamber is provided with a working gas channel, and the bottom of the remote plasma space is connected to the working gas channel, so that the accommodation space is connected with the remote plasma space.

In at least one embodiment, the non-contact wafer surface particle removal device further includes a sprinkler head to shield the working gas channel, and the sprinkler head has a plurality of holes, and these holes connect the remote plasma space and the accommodation space.

In at least one embodiment, the bias generating device includes two bias electrodes and a radio frequency current source. The two bias electrodes are arranged in the reaction chamber. The radio frequency current source is connected to the two bias electrodes to provide radio frequency current to the two bias electrodes. The bias electrode generates a bias electric field.

In at least one embodiment, the non-contact wafer surface particle removal device further includes a bearing tray, which is accommodated in the accommodation space; the bearing tray faces the top of the reaction chamber, and the bearing tray is used to hold the wafer to be cleaned ; A proximal plasma space is defined between the top of the reaction chamber and the carrier plate, and the bias generating device generates a bias electric field in the proximal plasma space.

In at least one embodiment, the non-contact wafer surface particle removal device further includes a first air inlet pipe, which is disposed in the plasma chamber and connected to the remote plasma space, and the first air inlet pipe is used to receive the working gas, Access the remote plasma space.

In at least one embodiment, the non-contact wafer surface particle removal device further includes a vacuum pump that passes through the accommodating space and is used to evacuate the accommodating space.

In at least one embodiment, the non-contact wafer surface particle removal device further includes a second gas inlet pipe connected to the plasma chamber or the reaction chamber for receiving a chemical reaction gas.

In at least one embodiment, the inner wall of the plasma chamber has a recessed mixing area, and the first air inlet pipe and the second air inlet pipe are connected to the mixing area.

In at least one embodiment, the induction coil and the bias generating device are activated at the same time; or the bias generating device is activated first and the induction coil is activated later.

This new method fully removes carbon particles on the wafer surface before growing the backside metal layer. Therefore, the back metal layer and the metal film can be bonded more reliably and are less likely to peel off when subjected to stress, thereby improving the yield during the production of semiconductor devices.

1:SiC wafer

2: Carrier board

3:Metal film

4: Back metal layer

5: Carbon particles

100: Non-contact wafer surface particle removal device

110:Reaction chamber

110a: Accommodation space

110b: Proximal plasma space

110c: Air extraction port

111:Top

112: Working gas channel

120: Carrying tray

130:Plasma cavity

132:Mixed area

130a: Distal plasma space

140:Induction coil

150: Bias voltage generating device

151:Bias electrode

152:RF current source

161:First air intake pipe

162:Second air intake pipe

170: Vacuum pump

180:Sprinkler head

210:SiC wafer

210a: Wafer to be cleaned

220: Carrier board

230:Metal film

240:Carbon particles

250:Back metal layer

P1: remote plasma

P2: proximal plasma

S110~S150: steps

Figure 1 is a schematic cross-sectional view of a SiC wafer in the prior art, revealing the BGBM process.

Figure 2 is a schematic cross-sectional view of a non-contact wafer surface particle removal device in an embodiment of the present invention.

Figure 3 is a schematic cross-sectional view of the SiC wafer in the new embodiment of the present invention, revealing the BGBM process.

Figure 4 is a flow chart of a method for removing carbon precipitation on the surface of a SiC wafer in an embodiment of the present invention.

Figure 5 is a schematic cross-sectional view of a non-contact wafer surface particle removal device in an embodiment of the present invention, revealing the process of plasma cleaning.

Figure 6 is a flow chart of another method for removing carbon precipitation on the surface of SiC wafer in an embodiment of the present invention.

7 and 8 are schematic cross-sectional views of a non-contact wafer surface particle removal device in embodiments of the present invention, revealing the process of plasma cleaning.

Figure 9 is a flow chart of another method for removing carbon precipitation on the surface of SiC wafer in an embodiment of the present invention.

Referring to FIGS. 2 and 3 , a non-contact wafer surface particle removal device 100 disclosed in a novel embodiment is applied to a method of removing carbon precipitation on the SiC wafer surface.

As shown in Figures 2 and 3, the non-contact wafer surface particle removal device 100 and the method for removing carbon precipitation on the surface of SiC wafer 210 are used to treat carbon particles precipitated due to the annealing process in the SiC wafer 210, causing subsequent metal The film layer is not easy to bond and falls off.

As shown in FIGS. 3 and 4 , a SiC wafer 210 is provided, as shown in step S110 and part (A) of FIG. 3 . Generally speaking, the front side of the SiC wafer 210 (the downward part in the figure) is temporarily bonded to a carrier 220 by adhesive or bonding, so that the carrier 220 is used to increase the mechanical strength of the SiC wafer 210. This prevents the SiC wafer 210 from being warped, deformed or broken due to stress during the grinding, thinning and polishing process.

As shown in Figures 3 and 4, coating equipment such as sputtering equipment is used to coat the back side of the SiC wafer 210 (the upward part in the figure) to form a metal film 230, as shown in step S120 and in Figure 3 ( Shown in part B). The material of the metal film 230 can be but is not limited to nickel, titanium alloy or aluminum, and is preferably nickel.

As shown in FIGS. 3 and 4 , an annealing process is then performed on the metal film 230 to precipitate the carbon particles 240 and accumulate on the surface of the metal film 230 , as shown in step S130 and part (C) of FIG. 3 . The annealing process may use a laser annealing process to quickly heat the shallow layer of the metal film 230 to achieve a shallow layer annealing effect and avoid overheating the SiC wafer 210 . The annealing process causes a chemical reaction between silicon atoms and nickel atoms to form nickel silicide to form an ohmic contact structure. As shown in part (C) of FIG. 3 , the formation of the aforementioned nickel silicide will cause the carbon particles 240 in SiC to precipitate and gradually accumulate on the surface of the metal film 230 .

As shown in FIGS. 3 and 4 , plasma is introduced to the surface of the metal film 230 , the surface of the metal film 230 is plasma cleaned, and the precipitated carbon particles 240 are removed, as shown in step S140 and part (D) of FIG. 3 Show.

As shown in FIGS. 3 and 4 , finally, a metal layer is grown on the metal film 230 to form a backside metal layer 250 . As shown in step S150 and part (E) of FIG. 3 , the BGBM process (Backside Grinding) is completed. & Backside Metallization, back grinding and back metallization). The growth of the aforementioned metal layer may be, but is not limited to, metal sputtering deposition (Metal Sputtering Deposition) or metal vaporization. Metal Evaporation Metallization. The material of the back metal layer 250 may be, but is not limited to, titanium (Ti), nickel vanadium alloy (NiV) or gold (Ag).

As shown in FIG. 2 , the process of introducing plasma to the surface of the metal film 230 and performing plasma cleaning on the surface of the metal film 230 can be performed through the non-contact wafer surface particle removal device 100 .

As shown in FIG. 2 , the non-contact wafer surface particle removal device 100 has a reaction chamber 110 , a carrier plate 120 , a plasma chamber 130 , an induction coil 140 and a bias voltage generating device 150 .

As shown in Figure 2, the reaction chamber 110 has an accommodation space 110a. The accommodation space 110a is used to accommodate the bearing tray 120, and the bearing tray 120 faces a top 111 of the reaction chamber 110. The carrier plate 120 is used to carry the wafer 210a to be cleaned. The wafer 210a to be cleaned is the SiC wafer 210 temporarily bonded or bonded to the carrier plate 220. The carrier plate 220 faces the carrier plate 120 and the SiC wafer 210 faces the carrier plate 120. Top 111.

As shown in FIG. 2 , a working gas channel 112 is provided on the top 111 of the reaction chamber 110 . The plasma chamber 130 is coupled to the top 111 of the reaction chamber 110 and covers the working gas channel 112 . There is a remote plasma space 130a inside the plasma chamber 130, and the bottom of the remote plasma space 130a is connected to the working gas channel 112, so that the accommodation space 110a is connected with the remote plasma space 130a. The remote plasma space 130a is used for a working gas, such as nitrogen (N2), oxygen (O2) or argon (Ar) to be introduced and enter the accommodating space 110a through the working gas channel 112.

As shown in FIG. 2 , the induction coil 140 surrounds the plasma chamber 130 to provide a time-varying magnetic flux to the remote plasma space 130 a to induce an electric field, so that the working gas located in the remote plasma space 130 a is freed. The plasma beam is generated and travels toward the accommodation space 110a. The working gas can enter the distal plasma space 130a through a first air inlet pipe 161. The distal plasma space 130a is used for the circulation of working gas, and enters the accommodation space 110a through the working gas channel 112. At the same time, the working gas in the remote plasma space 130a is ionized by the electric field to generate remote plasma P1, which is released into the volume through the working gas channel 112. Place space 110a. Specifically, the plasma chamber 130 and the induction coil 140 form an inductively coupled plasma generating device (Inductively Coupled Plasma, ICP).

As shown in FIG. 2 , the non-contact wafer surface particle removal device 100 further includes a spray head 180 to shield the working gas channel 112 . The sprinkler head 180 has a plurality of holes, which connect the distal plasma space 130a with the accommodation space 110a and/or the proximal plasma space 110b, so that the distal plasma P1 is more evenly distributed.

As shown in Figure 2, the bias voltage generating device 150 is used to generate a bias electric field that changes with time in the accommodation space 110a of the reaction chamber 110, so that the working gas in the accommodation space 110a is liberated into a proximal Plasma P2. In particular, a proximal plasma space 110b is defined between the top 111 of the reaction chamber 110 and the susceptor 120 . The bias generating device 150 generates a bias electric field in the proximal plasma space 110b of the reaction chamber 110 (the space between the top 111 and the carrier plate 120), so that the working gas located in the proximal plasma space 110b is liberated into a near-end plasma space 110b. Terminal plasma P2.

As shown in FIG. 2 , specifically, the bias generating device 150 includes two bias electrodes 151 and a radio frequency current source 152 . Two bias electrodes 151 are disposed in the reaction chamber 110 , and the proximal plasma space 110 b is located between the two bias electrodes 151 . The radio frequency current source 152 is connected to the two bias electrodes 151 to provide radio frequency current to the two bias electrodes 151 to generate a time-varying bias electric field in the accommodating space 110a or the proximal plasma space 110b. The working gas in the accommodation space 110a or the proximal plasma space 110b is liberated into proximal plasma P2. The two bias electrodes 151 can be electrical contacts, respectively connected to the top 111 and the bearing plate 120; the two bias electrodes 151 can also be a plate-like structure, respectively combined with the top 111 and the bearing plate 120, or they can be independently configured and located near the top 111 and the bearing plate 120. Both sides of the terminal plasma space 110b. Specifically, the bias voltage generating device 150 is a capacitive coupled plasma generating device (Capacitive Coupled Plasma, CCP).

In addition, the reaction chamber 110 also has an air extraction port 110c located below the bearing plate 120 . The air extraction port 110c is connected to a vacuum pump 170. The vacuum pump 170 is used to continuously pump air into the accommodation space 110a. An airflow is generated that continuously flows from the top 111 of the reaction chamber 110 to the bottom 112 of the reaction chamber 110 and passes through the surface of the carrier plate 120 so that the distal plasma P1 and the proximal plasma P2 can continue to act on the surface of the wafer 210a to be cleaned. , plasma cleaning is performed on the surface of the wafer 210a to be cleaned, and the precipitated carbon particles 240 are removed.

As shown in FIG. 2 , in addition, the non-contact wafer surface particle removal device 100 can further be provided with a second air inlet pipe 162 , and the second air inlet pipe 162 is connected to the plasma chamber 130 or the reaction chamber 110 . Preferably, the second air inlet pipe 162 is connected to the plasma chamber 130, and the inner wall of the plasma chamber 130 has a recessed mixing area 132, and the second air inlet pipe 162 is connected to this mixing area 132. The first air inlet pipe 161 is also connected to the mixing zone 132 . The second air inlet pipe 162 is used to be connected to a chemical reaction gas source, and is used to receive a chemical reaction gas to directly or indirectly pass into the accommodation space 110a through the plasma chamber 130. The chemical reaction gas source may be fluoride such as CF4 or SF6, which is used for chemical reaction cleaning of the metal film 230 of the wafer 210a to be cleaned to more fully remove precipitated carbon particles and other unnecessary compounds. The aforementioned mixing zone 132 allows the working gas and the chemical reaction gas to be fully mixed first, and then evenly distributed inside the plasma chamber 130 before being introduced into the reaction chamber 110 to avoid inconsistency in the distribution of the working gas and the chemical reaction gas. all.

Based on the non-contact wafer surface particle removal device 100, the step of plasma cleaning the surface of the metal film 230 can be divided into two modes.

As shown in FIG. 5 and FIG. 6 , the first mode is that the induction coil 140 and the bias voltage generating device 150 act simultaneously to generate distal plasma P1 and proximal plasma P2 and act on the surface of the wafer 210 a to be cleaned at the same time to perform the cleaning process. Plasma cleaning, as shown in steps S141 and S142. The remote plasma P1 generated by the induction coil 140 has effectively good uniformity, but its charge is reduced and its cleaning ability is weak. The proximal plasma P2 provided by the bias generating device 150 has a large charge and has better cleaning ability, but has poor uniformity. Therefore, the distal plasma P1 and the proximal plasma P2 are used for cleaning at the same time to ensure uniform cleaning of the wafer surface.

As shown in FIGS. 7 , 8 and 9 , the second mode is segmented cleaning. First, the proximal plasma P2 provided by the bias generating device 150 is used for better cleaning, as shown in step S143 . Then, the remote plasma P1 generated by the induction coil 140 is used for cleaning, as shown in step S144. The remote plasma P1 generated by the induction coil 140 has low charge damage to the wafer and has good uniformity. It can modify the surface of the wafer, allowing subsequent deposition and coating materials on the wafer surface. Has better adhesion.

In the present invention, before growing the backside metal layer 250, the carbon particles on the surface of the SiC wafer are fully removed. Therefore, the backside metal layer 250 and the metal film 230 can be more reliably combined and are less likely to peel off when subjected to stress, thereby improving the yield during the production of semiconductor devices.

100: Non-contact wafer surface particle removal device

110:Reaction chamber

110a: Accommodation space

110b: Proximal plasma space

110c: Air extraction port

111:Top

112: Working gas channel

120: Carrying tray

130:Plasma cavity

132:Mixed area

130a: Distal plasma space

140:Induction coil

150: Bias voltage generating device

151:Bias electrode

152:RF current source

161:First air intake pipe

162:Second air intake pipe

170: Vacuum pump

210a: Wafer to be cleaned

Claims (10)

A non-contact wafer surface particle removal device used to remove particles on the surface of a wafer to be cleaned, including: a reaction chamber with an accommodation space for accommodating the wafer to be cleaned; a plasma chamber body, coupled to a top of the reaction chamber; the interior of the plasma chamber has a remote plasma space connected to the accommodation space; an induction coil surrounds the plasma chamber for Providing time-varying magnetic flux to the remote plasma space to induce an electric field to ionize a working gas located in the remote plasma space to generate a remote plasma; and a bias voltage generating device for performing the reaction A bias electric field that changes with time is generated in the cavity, causing the working gas located in the reaction cavity to be liberated into a proximal plasma. The non-contact wafer surface particle removal device as claimed in claim 1, wherein a working gas channel is provided at a top of the reaction chamber, and the bottom of the remote plasma space is connected to the working gas channel, so that The accommodation space is connected with the remote plasma space. The non-contact wafer surface particle removal device as claimed in claim 2 further includes a sprinkler head to cover the working gas channel, and the sprinkler head has a plurality of holes, and the holes connect the remote plasma space and the accommodation space. The non-contact wafer surface particle removal device as claimed in claim 1, wherein the bias generating device includes two bias electrodes and a radio frequency current source, the two bias electrodes are disposed in the reaction chamber, and the radio frequency A current source is connected to the two bias electrodes to provide radio frequency current to cause the two bias electrodes to generate the bias electric field. The non-contact wafer surface particle removal device as claimed in claim 1, further comprising a bearing tray accommodated in the accommodation space; the bearing tray faces the top of the reaction chamber, and the bearing tray is used for The wafer to be cleaned is carried; a proximal plasma space is defined between the top of the reaction chamber and the carrier plate, and the bias generating device generates the bias electric field in the proximal plasma space. The non-contact wafer surface particle removal device as claimed in claim 1, further comprising a first air inlet pipe, which is disposed in the plasma chamber and connected to the remote plasma space, and the first air inlet pipe is used for The working gas is received and passed into the remote plasma space. The non-contact wafer surface particle removal device as claimed in claim 6 further includes a vacuum pump that passes through the accommodating space and is used to evacuate the accommodating space. The non-contact wafer surface particle removal device as claimed in claim 6 further includes a second air inlet pipe connected to the plasma chamber or the reaction chamber for receiving a chemical reaction gas. The non-contact wafer surface particle removal device as claimed in claim 8, wherein the inner wall of the plasma chamber has a recessed mixing zone, and the first air inlet pipe and the second air inlet pipe are connected to the Mixed zone. The non-contact wafer surface particle removal device as claimed in claim 1, wherein the induction coil and the bias generating device are activated at the same time; or the bias generating device is activated first and the induction coil is activated later.

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