Method for controlling stable state of nickel ingot in evaporation equipment

Abstract

The invention discloses a method for controlling the stable state of a nickel ingot in evaporation equipment, which comprises the following steps of: controlling the quantity of an evaporation source: keeping the liquid level of the evaporation source in a crucible close to a crucible opening, and keeping the liquid level height stable in the evaporation process; the crucible cleanliness is controlled, specifically, the crucible is cleaned regularly, and impurity pollution is eradicated; the evaporation source morphology control comprises the steps of source melting, beam spot adjustment, process parameter adjustment and the like. According to the source ingot control method disclosed by the invention, improvement is carried out in the aspects of process parameters, electron beam spot control, source ingot form control and crucible maintenance mode, the state of the source ingot is controlled to be stable fundamentally, and the occurrence probability of source splashing abnormity is reduced infinitely. Splash source scrapping or reworking abnormity caused by abnormity of the source ingot is reduced, and the product yield is improved. Shutdown for source melting due to abnormal state of the source ingot is reduced, and the utilization rate of equipment is improved.

Description

Technical Field

[0001] The invention relates to the technical field of chip backside film preparation, and in particular to a method for controlling the stable state of a nickel ingot in an evaporation device. Background Art

[0002] Back side metallization is a type of physical vapor deposition (PVD). It is a thin film preparation technology that uses physical methods to deposit metal materials on the back side of the thinned chip. The production of back side metallization can reduce the thermal resistance of the device, heat dissipation and cooling during operation; some power devices will lead out electrodes on the back side, so that the core electrodes have good ohmic contact characteristics, reliable welding, and can improve product reliability.

[0003] Electron beam evaporation is a type of vacuum evaporation coating. It is a method that uses electron beams to directly heat the evaporation material under vacuum conditions, vaporizes the evaporation material and transports it to the substrate, where it condenses to form a thin film. In the electron beam heating device, the heated material is placed in a water-cooled crucible to prevent the evaporation material from reacting with the crucible wall and affecting the quality of the film. Therefore, the electron beam evaporation deposition method can prepare high-purity thin films. At the same time, multiple crucibles can be placed in the same evaporation deposition device to achieve simultaneous or separate evaporation and deposition of multiple different substances (as shown in the attached manual). Figure 1 ). By electron beam evaporation, any material can be evaporated.

[0004] The hazards caused by the splashing of the evaporation source during electron beam evaporation are intuitively visible and can usually be divided into several levels. The most serious is that many large particles of the evaporation source splash onto the surface of the wafer, breaking it and dropping it; the minor one is that a small amount of the evaporation source splashes onto the surface of the wafer, forming granular small balls adhering to the surface. Therefore, the splashing of the evaporation source has a great influence on the coating quality on the back of the chip. Summary of the invention

[0005] In view of the above-mentioned problems, the present invention aims to provide a control method for stabilizing the state of nickel ingots in an evaporation device. The method can fundamentally reduce the splashing problem of the evaporation source caused by the abnormality of the source ingot and reduce the waste of evaporation materials caused by frequent melting of the source, thereby improving the coating quality on the back side of the chip.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is as follows: A method for controlling the stable state of nickel ingots in an evaporation device comprises the following steps:

[0007] S1. Control of evaporation source quantity: keep the evaporation source liquid level in the crucible close to the crucible mouth, and keep the liquid level stable during the evaporation process;

[0008] S2. Crucible cleanliness control: Clean the crucible regularly to prevent impurity contamination;

[0009] S3. Evaporation source morphology control

[0010] S31, molten source: control the surface of the source ingot to be smooth;

[0011] S32, beam spot adjustment: adjusting the beam spot position of the source ingot corresponding to the crucible so that the electron beam scanning position during the evaporation stage is located at the center of the source ingot;

[0012] S33. Process parameter adjustment: adjust the electron beam power in sequence during the evaporation, melting and post-evaporation stages of the source ingot, so that the source ingot is fully preheated in the evaporation stage, fully melted in the melting stage, and the morphology of the source ingot at the beam spot is slowly fixed in the stage after the evaporation ends.

[0013] Preferably, in step S1, the liquid level of the source ingot is controlled at 85%-90% of the height from the crucible opening.

[0014] Preferably, in step S2, the brass on the side wall is exposed when the crucible is cleaned, and the source ingot is placed stably in the crucible after cleaning.

[0015] Preferably, in step S31, the melting source process includes the following steps:

[0016] 1) Execution time: when the source ingot liquid level is lower than 2 / 3 of the crucible height, when there are too many burrs on the edge of the source ingot, or when the source ingot is replaced;

[0017] 2) Add Ni metal particles into the NI crucible using antistatic tweezers and evacuate the crucible;

[0018] 3) When the vacuum of the electron beam evaporation equipment chamber is evacuated to below 1E-3Pa, the planetary pot is turned on, and the EBGUN controller is switched to manual mode, and the electron gun controller is used for manual melting;

[0019] 4) Use a low-power electron beam to level the surface and edge of the source ingot, and move the electron beam to the center of the source ingot surface, slowly increase the power by 10% each time, and keep it for 15 seconds;

[0020] When the power is increased to 60-70%, the beam spot is moved to the center of the source ingot, and the source ingot is continuously output for 3 minutes to discharge impurities in the source ingot;

[0021] After the source ingot is melted, the beam spot power is reduced by 10% every 5 seconds until it reaches 0%;

[0022] 5) When the electron beam spot power is reduced to 0%, start timing, and break the cavity vacuum when the source ingot has cooled for more than 30 minutes.

[0023] Preferably, in step S32, during the source adding stage of each furnace, check whether the pit on the surface of the source ingot after the electron beam is scanned is in the center of the source ingot. If not, adjust the beam spot position of the crucible corresponding to the source ingot so that the electron beam is scanned in the center of the source ingot during the evaporation stage.

[0024] Preferably, step S32 includes the following steps:

[0025] 1) In the first stage of evaporation, PWR_RAMP01 and PWR_CNST01 are low-power heat sources. The PWR_CNST01 time is extended to fully preheat the source ingot;

[0026] 2) The second stage PWR_RAMP02 and PWR_CNST02 are the source ingot fully melted stage. In this stage, the electron beam power PARAMVALUE needs to be set to the power value when the thickness of the previous furnace evaporates to 1 / 3 and the rate is stable. This value is updated every 100 furnaces of the source ingot.

[0027] 3) The final stage PWR_RAMP03 is the stage where the electron gun reduces power after evaporation is completed. The duration of this stage is extended from 5 seconds to 20 seconds so that the electron beam energy does not disappear instantly.

[0028] The beneficial effects of the present invention are as follows: the source ingot control method disclosed in the present application improves various aspects from process parameters to electron beam spot control, source ingot morphology control and crucible maintenance methods, fundamentally stabilizes the source ingot state control, and infinitely reduces the probability of abnormal splash source occurrence. Reduces the scrapping or rework of splash sources caused by abnormal source ingots, and improves product yield. Reduces the need to shut down the melting source due to abnormal source ingot state, and improves equipment utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a diagram showing the current electron beam evaporation method for depositing a variety of different materials simultaneously or separately.

[0030] Figure 2 It is a diagram showing the liquid level of the source ingot in the crucible of the present invention.

[0031] Figure 3 Schematic diagram of the electron beam scanning position on the surface of the source ingot of the present invention. DETAILED DESCRIPTION

[0032] In order to enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0033] The applicant uses nickel metal particles to form a metal source ingot through multiple melting. During use, the overall source ingot morphology is uncontrollable, resulting in abnormal source ingot state, source ingots are prone to adsorb impurities, uneven placement, pits on the source ingot surface after evaporation, burrs and protrusions on the edge of the source ingot surface, and the source ingot height is too low, resulting in excessive electron beam spot power. These problems are mainly improved and controlled from the aspects of source ingot state control and process parameter setting.

[0034] See attached Figures 2-3 A method for controlling the stable state of a nickel ingot in an evaporation device is shown, comprising the following steps:

[0035] S1. Control of evaporation source quantity: Keep the evaporation source liquid level in the crucible close to the crucible mouth and keep the liquid level stable during the evaporation process. The specific method is: the evaporation source in the crucible must be added in time, and the source ingot liquid level is controlled at 85%-90% of the height of the crucible (such as Figure 2 ), source materials can be added before each furnace operation to prevent the liquid level from getting lower and lower, causing abnormalities such as source ingot contamination and excessive evaporation power.

[0036] S2. Crucible cleanliness control: Clean the crucible regularly, clean the side wall and bottom of the crucible every 5 furnaces to reduce the dust contamination of the source ingot. The specific cleaning process includes the following:

[0037] 1) After the source ingot has cooled, use a flat cleaning shovel (not shown) to take out the source ingot and place it aside. Do not touch it with dust-free cloth or other debris.

[0038] 2) Use a flat cleaning shovel to aim at the edge of the crucible and tap gently, but do not knock it into the crucible;

[0039] 3) Clean the inner wall and bottom of the crucible. Use a three-edged scraper (not shown) to scrape the side wall to make sure that the brass is exposed on the side wall.

[0040] 4) After cleaning, use a vacuum cleaner to clean the crucible to ensure that there are no impurities left in the crucible and that brass is exposed on the inner wall and bottom of the crucible;

[0041] 5) After checking that there is no abnormality in the source ingot, place the source ingot in the crucible to ensure that the source ingot is placed stably without shaking.

[0042] S3. Evaporation source morphology control

[0043] S31, molten source: control the surface of the source ingot to be smooth, specifically including the following steps:

[0044] 1) Execution time: when the source ingot liquid level is lower than 2 / 3 of the crucible height, when there are too many burrs on the edge of the source ingot, or when the source ingot is replaced;

[0045] 2) Add Ni metal particles into the NI crucible using antistatic tweezers and evacuate the device;

[0046] 3) When the chamber vacuum is evacuated to below 1E-3Pa, turn on the planetary pot, switch the EB GUN controller to manual, and use the electron gun controller to manually melt the source;

[0047] 4) Use a low-power electron beam to level the surface and the edge of the surface, and move the electron beam to the center of the source ingot surface, slowly increase the power by 10% each time, and keep it for 15 seconds. When the power reaches 60-70%, move the beam spot to the center of the source ingot, continue to output to the source ingot, keep it for 3 minutes, and discharge the impurities in the source ingot. After the source ingot is melted, the beam spot power needs to be reduced by 10% every 5 seconds until it is reduced to 0%, which can effectively ensure that the formation of pits on the surface of the source ingot is slowed down.

[0048] 5) When the electron beam spot power is reduced to 0%, start timing to ensure that the cavity vacuum is broken when the source ingot has cooled for more than 30 minutes.

[0049] S32, beam spot adjustment: adjust the beam spot position of the source ingot corresponding to the crucible, so that the electron beam scanning position in the evaporation stage is located at the center of the source ingot. The specific process is: in the source addition stage of each furnace, check whether the pit on the surface of the source ingot after the electron beam scans is in the center of the source ingot. If not, adjust the beam spot position of the crucible corresponding to the source ingot to ensure that the electron beam scans in the center of the source ingot during the evaporation stage (such as Figure 3 , the shallow pit in the small circle in the figure represents the electron beam scanning position) to prevent the beam spot from shifting during the evaporation process, and the source ingot from flowing down the side wall after melting, resulting in uneven heating on both sides of the source ingot and abnormal splashing.

[0050] S33, process parameter adjustment (as shown in Table 1 below): adjust the electron beam power in the stages of evaporation, melting and post-evaporation of the source ingot, so that the source ingot is fully preheated in the evaporation stage, fully melted in the melting stage, and the morphology of the source ingot at the beam spot is slowly fixed in the stage after the evaporation. Specifically, the following steps are included:

[0051] (1) In the first stage of the evaporation phase, the recipe (PWR_RAMP01 and PWR_CNST01) is mainly a low-power heat source, so the PWR_CNST01 time is extended to ensure that the source ingot is fully preheated.

[0052] (2) The second stage (PWR_RAMP02 and PWR_CNST02) is the stage when the source ingot is fully melted. In this stage, the electron beam power (PARAM VALUE) needs to be set to the power value when the thickness of the previous furnace evaporates to 1 / 3 and the rate is stable. This value is updated every 100 furnaces used for the source ingot.

[0053] (3) The last stage (PWR_RAMP03) is the stage where the electron gun reduces power after the evaporation is completed. The duration of this stage is extended from 5 seconds to 20 seconds to ensure that the electron beam energy does not disappear instantly. This causes the crucible to cool down and the source ingot morphology at the beam spot to be fixed too quickly, forming ingot pits on the surface of the source ingot, affecting the source addition operation of the next furnace and the source particle movement problem.

[0054]

[0055] Table 1 Source ingot evaporation, melting and post-evaporation stage process parameter adjustment

[0056] The principle of the present invention is: the source ingot control method disclosed in the present invention improves all aspects from process parameters, to electron beam spot management, to source ingot morphology control and crucible maintenance methods, fundamentally controls the source ingot state to be stable, infinitely reduces the probability of abnormal splashing source occurrence, reduces the scrapping or rework of splashing sources caused by abnormal source ingots, improves product yield, reduces the need to shut down the melting source due to abnormal source ingot state, and improves equipment utilization.

[0057] The above shows and describes the basic principle, main features and advantages of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention claimed.

Claims

1. A method for controlling the stable state of nickel ingots in an evaporation device, characterized in that: The following steps are involved: S1. Control of evaporation source quantity: keep the evaporation source liquid level in the crucible close to the crucible mouth, and keep the liquid level stable during the evaporation process; S2. Crucible cleanliness control: Clean the crucible regularly to prevent impurity contamination; S3. Evaporation source morphology control S31, molten source: control the surface of the source ingot to be smooth; S32, beam spot adjustment: adjusting the beam spot position of the source ingot corresponding to the crucible so that the electron beam scanning position during the evaporation stage is located at the center of the source ingot; S33. Process parameter adjustment: adjust the electron beam power in sequence during the evaporation, melting and post-evaporation stages of the source ingot, so that the source ingot is fully preheated in the evaporation stage, fully melted in the melting stage, and the morphology of the source ingot at the beam spot is slowly fixed in the stage after the evaporation ends.

2. The method for controlling the state stability of nickel ingots in an evaporation device according to claim 1, characterized in that: In step S1, the liquid level of the source ingot is controlled at 85%-90% of the height from the crucible opening.

3. The method for controlling the state stability of nickel ingots in an evaporation device according to claim 2, characterized in that: In step S2, the brass on the side wall of the crucible is exposed when the crucible is cleaned, and the source ingot is placed stably in the crucible after cleaning.

4. The method for controlling the state stability of nickel ingots in an evaporation device according to claim 3, characterized in that: In step S31, the melting source process includes the following steps: 1) Execution time: when the source ingot liquid level is lower than 2 / 3 of the crucible height, when there are too many burrs on the edge of the source ingot, or when the source ingot is replaced; 2) Add Ni metal particles into the Ni crucible using antistatic tweezers and evacuate the crucible; 3) When the vacuum of the electron beam evaporation equipment chamber is evacuated to below 1E-3Pa, the planetary pot is turned on, and the EB GUN controller is switched to manual mode, and the electron gun controller is used to manually melt the source; 4) Use a low-power electron beam to level the surface and edge of the source ingot, and move the electron beam to the center of the source ingot surface, slowly increase the power by 10% each time, and keep it for 15 seconds; When the power is increased to 60-70%, the beam spot is moved to the center of the source ingot, and the source ingot is continuously output for 3 minutes to discharge impurities in the source ingot; After the source ingot is melted, the beam power is reduced by 10% every 5 seconds until it reaches 0%; 5) When the electron beam spot power is reduced to 0%, start timing, and break the cavity vacuum when the source ingot has cooled for more than 30 minutes.

5. The method for controlling the state stability of nickel ingots in an evaporation device according to claim 4, characterized in that: In step S32, during the source adding stage of each furnace, check whether the pit on the surface of the source ingot after the electron beam is scanned is in the center of the source ingot. If not, adjust the beam spot position of the source ingot corresponding to the crucible so that the electron beam is scanned in the center of the source ingot during the evaporation stage.

6. The method for controlling the state stability of nickel ingots in an evaporation device according to claim 5, characterized in that: Step S32 includes the following steps: 1) In the first stage of evaporation, PWR_RAMP01 and PWR_CNST01 are low-power heat sources. The PWR_CNST01 time is extended to fully preheat the source ingot; 2) The second stage PWR_RAMP02 and PWR_CNST02 are the source ingot fully melted stage. In this stage, the electron beam power PARAMVALUE needs to be set to the power value when the thickness of the previous furnace evaporates to 1 / 3 and the rate is stable. This value is updated every 100 furnaces of the source ingot. 3) The final stage PWR_RAMP03 is the stage where the electron gun reduces power after evaporation is completed. The duration of this stage is extended from 5 seconds to 20 seconds so that the electron beam energy does not disappear instantly.

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