The lithographic method of etching super-thick non-photosensitive photoresist
Technical field
The invention belongs to the semiconductor making method in microelectronic chip manufacture field.
Background technology
For high-voltage power element, in order to improve its reliability under high-temperature high-pressure work environment, it usually needs
Use the thickest photoresist as sealer, ensure internal components normal work under extreme operating conditions
Make (such as more than 6000V conducting voltage, 400 degree of high temperature above are persistently more than in the working environment of 30min).
In order to completely cut off high-voltage breakdown and hot operation for a long time, the thickness of photoresist is the thickest.Photoetching herein
Glue is typically polyimide (polyimides).
Polyimide is a kind of high-molecular organic material, is divided into photonasty and non-photosensitive two kinds.Non-photosensitive
It is typically directly polyimide precursor (Polyimide Procursor, the most typically polyamic acid
Polyamic acid), polyimide precursor generally there are open loop structure, and can be etched the wet of photoresist
Method method medicinal liquid is removed;Photonasty then by increase on polyimide precursor heliosensitivity functional group and
The functional group that suppression is dissolved, causes the reaction of photoactivatable groups by photochemical reaction thus removes and suppress molten
The functional group solved, produces polyimide precursor.
Then after polyimide precursor is by heating by uniform temperature, there is imidization, form closed loop,
Thus the wet method method medicinal liquid insoluble in etching photoresist, and form the resinoid with certain mechanical/electrical intensity
Material.Typical polyimide precursor molecular formula and imidization can be expressed as:
Generally in the semiconductor technology course of processing, for simplicity, by photosensitive in actual production factory
Property polyimide exposure before, Polyiamic Precursor after exposure;Non-photosensitive polyimid adds hot polymerization
Before closing, Polyiamic Precursor etc. are commonly referred to as polyimide.
In actual chips manufacture process, photoresist generally uses wet etching, and now because photoresist is thick
Spend the thickest, it usually needs etching for a long time, or multiple etching, its production capacity is the lowest, causes manufacturing cost
The highest.
It addition, when the thickness of photoresist is more than time to a certain degree, such as 15um, be difficult to by the most exposed
Journey is allowed to react completely, and is removed, it is therefore desirable to the photoresist of practical non-photosensitive, coordinates light simultaneously
Photoresist is patterned, and the most with photoresist as mask, performs etching non-photosensitive photoresist, generally
All use wet etching.
The normal development technique of photoresist is: exposure, PEB (after bake), and development is cleaned.Wherein PEB master
The light acid that fill-in light photoresist to be act as produces in exposure process is diffused, and makes photoresist by heating
Environment is higher than its activation energy, carrys out fill-in light chemical reaction and occurs.Therefore in usual technique, PEB step is necessary
's.
Summary of the invention
The technical problem to be solved is to provide a kind of etching side etching super-thick non-photosensitive photoresist
Method, it can reduce the etch period of super thick photoresist, improve production capacity, reduce manufacturing cost.
In order to solve above technical problem, the invention provides the etching work of a kind of super-thick non-photosensitive photoresist
Process, comprises the following steps: spin coating non-photosensitive photoresist;Spin coating photoresist;Exposure photo-etching glue, and
Directly develop;Silicon chip erosion is also carried out.
The beneficial effects of the present invention is: reduce the etch period of super thick photoresist, improve production capacity, reduce system
Cause this.
Wet etching medicinal liquid is tetramethyl aqua ammonia TMAH, gamma-butyrolacton GBL, N-Methyl pyrrolidone NMP,
Propylene glycol monomethyl ether PGME, the pure solution of propylene glycol methyl ether acetate PGMEA or mixed solution.
Thickness G T.GT.GT 15um after its spin coating of photoresist thickness.
Photoresist is applied to 400 degree of high temperature above working environments, high-temperature duration > 30 minutes.
The concrete technology flow process of the non-photosensitive photoresist in step 1 is:
150 degree~250 degree dehydration preliminary dryings;
Spin coating non-sightseeing photoresist;
100~130 degree of front bakings;
20 degree~30 degree of room temperature coolings.
Described non-photosensitive photoresist be non-photosensitive polyimide precursor (Polyamic Precursor,
It is typically polyamic acid Polyimide Acid) or non-photosensitive polyimides (Polyimide).
Accompanying drawing explanation
With detailed description of the invention, the present invention is described in further detail below in conjunction with the accompanying drawings.
Fig. 1 is the decay with heating-up temperature/time of the photoresist etching.
Detailed description of the invention
Reduce the etch period of super thick photoresist, improve production capacity, reduce manufacturing cost.It is found by experiment that system
The thermal process relation that about photoresist etch rate experiences with it is very big, and heat time heating time is the longest, under its etch rate
Drop the most obvious.
As a example by 2.3%TMAH is for etching medicinal liquid, non-photosensitive photoresist is non-photosensitive polyimide, thick
Degree 20um.When heat budget is at 130 degree, 300s, and interior its etch rate about 0.2um/s, if but temperature is high
In 135 degree, or total heat time heating time is more than 400s, then developing rate i.e. drops to 0.05um/s and tends towards stability,
If therefore done according to conventional PEB technique, need to increase 80-150 degree, the thermal process of 60s-90s, its
Etch rate declines clearly.
This patent is by removing PEB step, and its developing rate can rise 20%~30%, and single developing time is big
Big reduction.
To be applied to as a example by 2.3% tetramethyl aqua ammonia TMAH is for etching medicinal liquid in this example, etch 40um
The photoresist of thickness.(wet etching medicinal liquid can use other such as gamma-butyrolacton GBL, N-Methyl pyrrolidone
NMP, propylene glycol monomethyl ether PGME, the pure solution of propylene glycol methyl ether acetate PGMEA or mixed solution.) described
Non-photosensitive photoresist can be polyimides polyimide.
First spin coating non-photosensitive photoresist, its processing step is:
1) 150 degree~250 degree dehydration preliminary dryings;
2) spin coating non-sightseeing photoresist;
3) 100~130 degree of front bakings;
4) 20 degree~30 degree of room temperature coolings.
Single material discharge-amount is 3~50ml, spin coating main rotating speed speed 500-2000rpm, can be two step groups
Become, low speed+at a high speed, the front baking time is 120s-240s, no more than 240s.
Secondly spin coating photoresist, its step is similar with spin coating photoresist, and discharge-amount is 0.5-5ml, spin coating speed
1500-3500rpm, front baking time 45-90s
Exposure imaging, step is, after exposure completes, to be directly entered developing cell and develop, without PEB step.
The present invention is not limited to embodiment discussed above.Description to detailed description of the invention is intended to above
In order to describe and the technical scheme that the present invention relates to be described.Obvious conversion based on present invention enlightenment or
Replacement should also be as being considered within protection scope of the present invention.Above detailed description of the invention is used for disclosing this
Bright optimal implementation, so that those of ordinary skill in the art can apply the multiple enforcement of the present invention
Mode and multiple alternative reach the purpose of the present invention.