阅读说明：本技术 一种半导体三极管表面lpcvd钝化膜及其制备方法 (Semiconductor triode surface LPCVD passive film and preparation method thereof ) 是由 孙金凯 叶婵 于佳宁 毛英女 秦达 马叙广 张洪艳 张阳 王丹 谢胜涛 于 2021-08-16 设计创作，主要内容包括：一种半导体三极管表面LPCVD钝化膜及其制备方法,属于芯片钝化膜制备技术领域。本发明的目的是为了解决现有半导体三极管性能不稳定的问题,所述钝化膜由硅氧多结构混合物和氮化硅两层组成,其中硅氧多结构混合物贴近三极管,氮化硅在外侧贴近外界。在现有三极管光刻之后,将三极管放入LPCVD设备中,同时通入笑气、硅烷和惰性气体的混合物,控制笑气与硅烷的体积比为20:80,沉积掺氧多晶硅,然后再改为通入氨气、硅烷和惰性气体的混合物,控制氮气和硅烷的体积比为50:18,沉积氮化硅。本发明加入LPCVD工艺作为表面保护结构,强化其可靠性,稳定性。由原产品参数在-50℃～150℃和室温的参数变化率25～30％,降至20％以下。(An LPCVD passive film on the surface of a semiconductor triode and a preparation method thereof belong to the technical field of chip passive film preparation. The passivation film is composed of a silicon-oxygen multi-structure mixture and a silicon nitride layer, wherein the silicon-oxygen multi-structure mixture is close to the triode, and the silicon nitride layer is close to the outside. After the existing triode is photoetched, the triode is placed into LPCVD equipment, a mixture of laughing gas, silane and inert gas is simultaneously introduced, the volume ratio of the laughing gas to the silane is controlled to be 20:80, oxygen-doped polysilicon is deposited, then a mixture of ammonia gas, silane and inert gas is introduced instead, the volume ratio of nitrogen gas to silane is controlled to be 50:18, and silicon nitride is deposited. The invention adds LPCVD technology as surface protection structure to strengthen its reliability and stability. The parameter change rate of the original product at-50-150 ℃ and room temperature is reduced to below 20 percent from 25-30 percent.)

1. A semiconductor triode surface LPCVD passive film is characterized in that: the passivation film is composed of a silicon-oxygen multi-structure mixture and a silicon nitride layer, wherein the silicon-oxygen multi-structure mixture is close to the triode, and the silicon nitride layer is close to the outside.

2. A method for preparing a semiconductor triode surface LPCVD passive film according to claim 1, characterized in that: after the existing triode is photoetched, the triode is placed into LPCVD equipment, a mixture of laughing gas, silane and inert gas is simultaneously introduced, the volume ratio of the laughing gas to the silane is controlled to be 20:80, the reaction is carried out for 80 minutes at the temperature of 600 ℃ under the low pressure of 100PS, oxygen-doped polysilicon is obtained through deposition, then the mixture of ammonia gas, the silane and the inert gas is introduced, the volume ratio of the nitrogen gas to the silane is controlled to be 50:18, and the reaction is carried out for 120 minutes at the temperature of 800 ℃ under the low pressure of 100PS, so that silicon nitride is deposited.

3. The method for preparing the LPCVD passive film on the surface of the semiconductor triode according to claim 2, characterized in that: the silane is monosilane.

Technical Field

The invention belongs to the technical field of preparation of chip passivation films, and particularly relates to a semiconductor triode surface LPCVD passivation film and a preparation method thereof.

Background

The specific process flow of the existing semiconductor triode at present comprises the following steps: oxidation → photolithography → boron diffusion → photolithography → phosphorus diffusion → photolithography → glass passivation → photolithography → aluminum evaporation → photolithography → aluminum alloy → photolithography → back side thinning → back side multilayer metallization → scribing → die testing → sintering → pressing line → sealing cap → middle testing → printing → screening and packaging warehousing. Due to the high reliability of the user requirements, the semiconductor triode is unstable in extreme high-temperature environment, low-temperature environment and the like, so that the current user requirements cannot be met, and a new process needs to be developed or the existing process needs to be improved, so that the performance of the triode is more stable.

Disclosure of Invention

The invention aims to solve the problem of unstable performance of the conventional semiconductor triode and provides a semiconductor triode surface LPCVD (low pressure chemical vapor deposition) passivation film and a preparation method thereof.

LPCVD is also called passivation film technology of high temperature and low pressure vapor deposition, and refers to the passivation film compounded by silicon-oxygen multi-structure mixture and silicon nitride. The technology is not available in the production of the original triode discrete device, and is used for optimizing the addition of an LPCVD technology on a chip of the triode.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

the LPCVD passive film for the surface of semiconductor triode is composed of two layers of silicon-oxygen mixture and silicon nitride, in which the silicon-oxygen mixture is near the triode and the silicon nitride is near the outside.

After the existing triode is subjected to photoetching, the triode is placed into LPCVD equipment, a mixture of laughing gas, silane and inert gas is introduced at the same time, the volume ratio of the laughing gas to the silane is controlled to be 20:80, the reaction is carried out for 80 minutes at the temperature of 600 ℃ under the low pressure of 100PS, oxygen-doped polysilicon is obtained through deposition, then the mixture of ammonia gas, the silane and the inert gas is introduced, the volume ratio of the nitrogen gas to the silane is controlled to be 50:18, and the reaction is carried out for 120 minutes at the temperature of 800 ℃ under the low pressure of 100PS, so that silicon nitride is deposited.

Compared with the prior art, the invention has the beneficial effects that:

(1) the LPCVD surface composite passivation technology is a surface protection technology in a semiconductor, and the technology is firstly used in the production of high-power triode discrete devices in the factory.

(2) The LPCVD surface composite passivation process is optimized, LPCVD equipment is used in the original triode production flow, and an LPCVD process is added to serve as a surface protection structure, so that the reliability and the stability of the device are enhanced. The parameter change rate of original product parameters at-50-150 ℃ and room temperature is reduced to below 20 percent by 25-30 percent (the ratio of the difference between the high-temperature and low-temperature measurement parameters and the normal-temperature measurement parameters to the room temperature).

(3) The process adds a layer of non-metal composite passive film on the original structure, can improve the performance parameters in the aspect of reliability, and most of the non-metal composite passive film is obtained by indirect measurement through experiments. The technology is suitable for being adjusted by adding the triode which is a mature technology of our factory and is only used for the diode product before.

(4) The LPCVD equipment is the common equipment in our factory for the self-created mature process, but is not used in the series of triode products before being used only in the diode products, and is added in the triode for the first time.

Detailed Description

The technical solutions of the present invention are further described below with reference to examples, but the present invention is not limited thereto, and any modifications or equivalent substitutions may be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

The invention has the following processes: oxidation → photolithography → boron diffusion → photolithography → phosphorus diffusion → photolithography → LPCVD → glass passivation → photolithography → aluminum evaporation → photolithography → aluminum alloy → photolithography → back thinning → back multi-layer metallization → scribing → die testing → sintering → pressing line → capping → middle testing → printing → screening and packaging warehousing.

The first embodiment is as follows: the present embodiment describes a semiconductor triode surface LPCVD passivation film comprising a two-layer silicon-oxygen multi-structure mixture and silicon nitride, wherein the ratio of oxygen in the silicon-oxygen multi-structure mixture is about 23 to 27%, and the silicon nitride is Si₃N₄The deposition layer, the silicon-oxygen multi-structure mixture is close to the triode, and the silicon nitride is close to the outside. The proportion of oxygen is preferably 24 to 26%, and more preferably 25%.

The second embodiment is as follows: a method for preparing a semiconductor triode surface LPCVD passive film includes putting a triode into LPCVD equipment after photoetching of the conventional triode, simultaneously introducing a mixture of laughing gas, silane and inert gas, controlling the volume ratio of the laughing gas to the silane to be 20:80, reacting for 80 minutes at a temperature of 600 ℃ under a low pressure of 100PS (pressure unit) to deposit oxygen-doped polysilicon, introducing a mixture of ammonia gas, silane and inert gas, controlling the volume ratio of the nitrogen gas to the silane to be 50:18, and reacting for 120 minutes at a temperature of 800 ℃ under a low pressure of 100PS (pressure unit) to deposit silicon nitride.

The third concrete implementation mode: in a method for preparing a semiconductor triode surface LPCVD passivation film according to the second embodiment, the silane is monosilane.

Example 1:

a preparation method of a semiconductor triode surface LPCVD passive film comprises the steps of placing a triode into LPCVD equipment after photoetching of the conventional triode, simultaneously introducing a mixture of laughing gas, silane and inert gas, controlling the volume ratio of the laughing gas to the silane to be 20:80, reacting for 80 minutes at the temperature of 600 ℃ under the low pressure of 100PS (pressure unit) to obtain oxygen-doped polycrystalline silicon through deposition, then introducing a mixture of ammonia gas, silane and inert gas, controlling the volume ratio of the nitrogen gas to the silane to be 50:18, and reacting for 120 minutes at the temperature of 800 ℃ under the low pressure of 100PS (pressure unit) to deposit silicon nitride.

And (3) testing conditions are as follows: and (3) connecting a lead of the finished triode, putting the lead into a constant-temperature oven at 125 ℃, leading the lead out of the oven, and measuring the lead outside the oven by using a testing device which is a QT2 type semiconductor graphic instrument (testing device). And the low temperature is also measured by putting the product into a low-temperature refrigerator and leading out the product by a lead wire.

Through tests, the difference between the static value of the forward current transfer ratio of the common emitter at room temperature of the triode and the static value of the forward current transfer ratio of the common emitter at 125-55 ℃ is reduced by 5% to the extreme with the difference between the static value of the forward current transfer ratio of the common emitter without LPCVD equipment and technology. Other parameters of the product at extreme operating temperatures are also significantly improved. Under the condition of not changing other production processes and processes, the stability of the product can be effectively improved, the increase and decrease of the cost can be effectively controlled, and higher performance improvement can be obtained at limited cost increase.